diff options
Diffstat (limited to 'kernel/workqueue.c')
| -rw-r--r-- | kernel/workqueue.c | 7428 |
1 files changed, 5249 insertions, 2179 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index f02c4a4a0c3c..253311af47c6 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1,3 +1,4 @@ +// SPDX-License-Identifier: GPL-2.0-only /* * kernel/workqueue.c - generic async execution with shared worker pool * @@ -16,17 +17,19 @@ * * This is the generic async execution mechanism. Work items as are * executed in process context. The worker pool is shared and - * automatically managed. There is one worker pool for each CPU and - * one extra for works which are better served by workers which are - * not bound to any specific CPU. + * automatically managed. There are two worker pools for each CPU (one for + * normal work items and the other for high priority ones) and some extra + * pools for workqueues which are not bound to any specific CPU - the + * number of these backing pools is dynamic. * - * Please read Documentation/workqueue.txt for details. + * Please read Documentation/core-api/workqueue.rst for details. */ #include <linux/export.h> #include <linux/kernel.h> #include <linux/sched.h> #include <linux/init.h> +#include <linux/interrupt.h> #include <linux/signal.h> #include <linux/completion.h> #include <linux/workqueue.h> @@ -37,7 +40,6 @@ #include <linux/hardirq.h> #include <linux/mempolicy.h> #include <linux/freezer.h> -#include <linux/kallsyms.h> #include <linux/debug_locks.h> #include <linux/lockdep.h> #include <linux/idr.h> @@ -47,10 +49,16 @@ #include <linux/nodemask.h> #include <linux/moduleparam.h> #include <linux/uaccess.h> +#include <linux/sched/isolation.h> +#include <linux/sched/debug.h> +#include <linux/nmi.h> +#include <linux/kvm_para.h> +#include <linux/delay.h> +#include <linux/irq_work.h> #include "workqueue_internal.h" -enum { +enum worker_pool_flags { /* * worker_pool flags * @@ -64,15 +72,20 @@ enum { * be executing on any CPU. The pool behaves as an unbound one. * * Note that DISASSOCIATED should be flipped only while holding - * manager_mutex to avoid changing binding state while - * create_worker() is in progress. + * wq_pool_attach_mutex to avoid changing binding state while + * worker_attach_to_pool() is in progress. + * + * As there can only be one concurrent BH execution context per CPU, a + * BH pool is per-CPU and always DISASSOCIATED. */ - POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ + POOL_BH = 1 << 0, /* is a BH pool */ + POOL_MANAGER_ACTIVE = 1 << 1, /* being managed */ POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ - POOL_FREEZING = 1 << 3, /* freeze in progress */ + POOL_BH_DRAINING = 1 << 3, /* draining after CPU offline */ +}; +enum worker_flags { /* worker flags */ - WORKER_STARTED = 1 << 0, /* started */ WORKER_DIE = 1 << 1, /* die die die */ WORKER_IDLE = 1 << 2, /* is idle */ WORKER_PREP = 1 << 3, /* preparing to run works */ @@ -82,7 +95,14 @@ enum { WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE | WORKER_UNBOUND | WORKER_REBOUND, +}; +enum work_cancel_flags { + WORK_CANCEL_DELAYED = 1 << 0, /* canceling a delayed_work */ + WORK_CANCEL_DISABLE = 1 << 1, /* canceling to disable */ +}; + +enum wq_internal_consts { NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */ UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */ @@ -99,15 +119,24 @@ enum { /* * Rescue workers are used only on emergencies and shared by - * all cpus. Give -20. + * all cpus. Give MIN_NICE. */ - RESCUER_NICE_LEVEL = -20, - HIGHPRI_NICE_LEVEL = -20, + RESCUER_NICE_LEVEL = MIN_NICE, + HIGHPRI_NICE_LEVEL = MIN_NICE, - WQ_NAME_LEN = 24, + WQ_NAME_LEN = 32, + WORKER_ID_LEN = 10 + WQ_NAME_LEN, /* "kworker/R-" + WQ_NAME_LEN */ }; /* + * We don't want to trap softirq for too long. See MAX_SOFTIRQ_TIME and + * MAX_SOFTIRQ_RESTART in kernel/softirq.c. These are macros because + * msecs_to_jiffies() can't be an initializer. + */ +#define BH_WORKER_JIFFIES msecs_to_jiffies(2) +#define BH_WORKER_RESTARTS 10 + +/* * Structure fields follow one of the following exclusion rules. * * I: Modifiable by initialization/destruction paths and read-only for @@ -118,73 +147,110 @@ enum { * * L: pool->lock protected. Access with pool->lock held. * - * X: During normal operation, modification requires pool->lock and should - * be done only from local cpu. Either disabling preemption on local - * cpu or grabbing pool->lock is enough for read access. If - * POOL_DISASSOCIATED is set, it's identical to L. + * LN: pool->lock and wq_node_nr_active->lock protected for writes. Either for + * reads. + * + * K: Only modified by worker while holding pool->lock. Can be safely read by + * self, while holding pool->lock or from IRQ context if %current is the + * kworker. * - * MG: pool->manager_mutex and pool->lock protected. Writes require both - * locks. Reads can happen under either lock. + * S: Only modified by worker self. + * + * A: wq_pool_attach_mutex protected. * * PL: wq_pool_mutex protected. * - * PR: wq_pool_mutex protected for writes. Sched-RCU protected for reads. + * PR: wq_pool_mutex protected for writes. RCU protected for reads. + * + * PW: wq_pool_mutex and wq->mutex protected for writes. Either for reads. + * + * PWR: wq_pool_mutex and wq->mutex protected for writes. Either or + * RCU for reads. * * WQ: wq->mutex protected. * - * WR: wq->mutex protected for writes. Sched-RCU protected for reads. + * WR: wq->mutex protected for writes. RCU protected for reads. + * + * WO: wq->mutex protected for writes. Updated with WRITE_ONCE() and can be read + * with READ_ONCE() without locking. * * MD: wq_mayday_lock protected. + * + * WD: Used internally by the watchdog. */ /* struct worker is defined in workqueue_internal.h */ struct worker_pool { - spinlock_t lock; /* the pool lock */ + raw_spinlock_t lock; /* the pool lock */ int cpu; /* I: the associated cpu */ int node; /* I: the associated node ID */ int id; /* I: pool ID */ - unsigned int flags; /* X: flags */ + unsigned int flags; /* L: flags */ + + unsigned long watchdog_ts; /* L: watchdog timestamp */ + bool cpu_stall; /* WD: stalled cpu bound pool */ + + /* + * The counter is incremented in a process context on the associated CPU + * w/ preemption disabled, and decremented or reset in the same context + * but w/ pool->lock held. The readers grab pool->lock and are + * guaranteed to see if the counter reached zero. + */ + int nr_running; struct list_head worklist; /* L: list of pending works */ - int nr_workers; /* L: total number of workers */ - /* nr_idle includes the ones off idle_list for rebinding */ - int nr_idle; /* L: currently idle ones */ + int nr_workers; /* L: total number of workers */ + int nr_idle; /* L: currently idle workers */ - struct list_head idle_list; /* X: list of idle workers */ + struct list_head idle_list; /* L: list of idle workers */ struct timer_list idle_timer; /* L: worker idle timeout */ - struct timer_list mayday_timer; /* L: SOS timer for workers */ + struct work_struct idle_cull_work; /* L: worker idle cleanup */ + + struct timer_list mayday_timer; /* L: SOS timer for workers */ /* a workers is either on busy_hash or idle_list, or the manager */ DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER); /* L: hash of busy workers */ - /* see manage_workers() for details on the two manager mutexes */ - struct mutex manager_arb; /* manager arbitration */ - struct mutex manager_mutex; /* manager exclusion */ - struct idr worker_idr; /* MG: worker IDs and iteration */ + struct worker *manager; /* L: purely informational */ + struct list_head workers; /* A: attached workers */ + + struct ida worker_ida; /* worker IDs for task name */ struct workqueue_attrs *attrs; /* I: worker attributes */ struct hlist_node hash_node; /* PL: unbound_pool_hash node */ int refcnt; /* PL: refcnt for unbound pools */ - - /* - * The current concurrency level. As it's likely to be accessed - * from other CPUs during try_to_wake_up(), put it in a separate - * cacheline. - */ - atomic_t nr_running ____cacheline_aligned_in_smp; - +#ifdef CONFIG_PREEMPT_RT + spinlock_t cb_lock; /* BH worker cancel lock */ +#endif /* - * Destruction of pool is sched-RCU protected to allow dereferences + * Destruction of pool is RCU protected to allow dereferences * from get_work_pool(). */ struct rcu_head rcu; -} ____cacheline_aligned_in_smp; +}; + +/* + * Per-pool_workqueue statistics. These can be monitored using + * tools/workqueue/wq_monitor.py. + */ +enum pool_workqueue_stats { + PWQ_STAT_STARTED, /* work items started execution */ + PWQ_STAT_COMPLETED, /* work items completed execution */ + PWQ_STAT_CPU_TIME, /* total CPU time consumed */ + PWQ_STAT_CPU_INTENSIVE, /* wq_cpu_intensive_thresh_us violations */ + PWQ_STAT_CM_WAKEUP, /* concurrency-management worker wakeups */ + PWQ_STAT_REPATRIATED, /* unbound workers brought back into scope */ + PWQ_STAT_MAYDAY, /* maydays to rescuer */ + PWQ_STAT_RESCUED, /* linked work items executed by rescuer */ + + PWQ_NR_STATS, +}; /* - * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS + * The per-pool workqueue. While queued, bits below WORK_PWQ_SHIFT * of work_struct->data are used for flags and the remaining high bits * point to the pwq; thus, pwqs need to be aligned at two's power of the * number of flag bits. @@ -197,21 +263,41 @@ struct pool_workqueue { int refcnt; /* L: reference count */ int nr_in_flight[WORK_NR_COLORS]; /* L: nr of in_flight works */ + bool plugged; /* L: execution suspended */ + + /* + * nr_active management and WORK_STRUCT_INACTIVE: + * + * When pwq->nr_active >= max_active, new work item is queued to + * pwq->inactive_works instead of pool->worklist and marked with + * WORK_STRUCT_INACTIVE. + * + * All work items marked with WORK_STRUCT_INACTIVE do not participate in + * nr_active and all work items in pwq->inactive_works are marked with + * WORK_STRUCT_INACTIVE. But not all WORK_STRUCT_INACTIVE work items are + * in pwq->inactive_works. Some of them are ready to run in + * pool->worklist or worker->scheduled. Those work itmes are only struct + * wq_barrier which is used for flush_work() and should not participate + * in nr_active. For non-barrier work item, it is marked with + * WORK_STRUCT_INACTIVE iff it is in pwq->inactive_works. + */ int nr_active; /* L: nr of active works */ - int max_active; /* L: max active works */ - struct list_head delayed_works; /* L: delayed works */ + struct list_head inactive_works; /* L: inactive works */ + struct list_head pending_node; /* LN: node on wq_node_nr_active->pending_pwqs */ struct list_head pwqs_node; /* WR: node on wq->pwqs */ struct list_head mayday_node; /* MD: node on wq->maydays */ + u64 stats[PWQ_NR_STATS]; + /* - * Release of unbound pwq is punted to system_wq. See put_pwq() - * and pwq_unbound_release_workfn() for details. pool_workqueue - * itself is also sched-RCU protected so that the first pwq can be - * determined without grabbing wq->mutex. + * Release of unbound pwq is punted to a kthread_worker. See put_pwq() + * and pwq_release_workfn() for details. pool_workqueue itself is also + * RCU protected so that the first pwq can be determined without + * grabbing wq->mutex. */ - struct work_struct unbound_release_work; + struct kthread_work release_work; struct rcu_head rcu; -} __aligned(1 << WORK_STRUCT_FLAG_BITS); +} __aligned(1 << WORK_STRUCT_PWQ_SHIFT); /* * Structure used to wait for workqueue flush. @@ -225,12 +311,32 @@ struct wq_flusher { struct wq_device; /* + * Unlike in a per-cpu workqueue where max_active limits its concurrency level + * on each CPU, in an unbound workqueue, max_active applies to the whole system. + * As sharing a single nr_active across multiple sockets can be very expensive, + * the counting and enforcement is per NUMA node. + * + * The following struct is used to enforce per-node max_active. When a pwq wants + * to start executing a work item, it should increment ->nr using + * tryinc_node_nr_active(). If acquisition fails due to ->nr already being over + * ->max, the pwq is queued on ->pending_pwqs. As in-flight work items finish + * and decrement ->nr, node_activate_pending_pwq() activates the pending pwqs in + * round-robin order. + */ +struct wq_node_nr_active { + int max; /* per-node max_active */ + atomic_t nr; /* per-node nr_active */ + raw_spinlock_t lock; /* nests inside pool locks */ + struct list_head pending_pwqs; /* LN: pwqs with inactive works */ +}; + +/* * The externally visible workqueue. It relays the issued work items to * the appropriate worker_pool through its pool_workqueues. */ struct workqueue_struct { struct list_head pwqs; /* WR: all pwqs of this wq */ - struct list_head list; /* PL: list of all workqueues */ + struct list_head list; /* PR: list of all workqueues */ struct mutex mutex; /* protects this wq */ int work_color; /* WQ: current work color */ @@ -241,60 +347,145 @@ struct workqueue_struct { struct list_head flusher_overflow; /* WQ: flush overflow list */ struct list_head maydays; /* MD: pwqs requesting rescue */ - struct worker *rescuer; /* I: rescue worker */ + struct worker *rescuer; /* MD: rescue worker */ int nr_drainers; /* WQ: drain in progress */ - int saved_max_active; /* WQ: saved pwq max_active */ - struct workqueue_attrs *unbound_attrs; /* WQ: only for unbound wqs */ - struct pool_workqueue *dfl_pwq; /* WQ: only for unbound wqs */ + /* See alloc_workqueue() function comment for info on min/max_active */ + int max_active; /* WO: max active works */ + int min_active; /* WO: min active works */ + int saved_max_active; /* WQ: saved max_active */ + int saved_min_active; /* WQ: saved min_active */ + + struct workqueue_attrs *unbound_attrs; /* PW: only for unbound wqs */ + struct pool_workqueue __rcu *dfl_pwq; /* PW: only for unbound wqs */ #ifdef CONFIG_SYSFS struct wq_device *wq_dev; /* I: for sysfs interface */ #endif #ifdef CONFIG_LOCKDEP - struct lockdep_map lockdep_map; + char *lock_name; + struct lock_class_key key; + struct lockdep_map __lockdep_map; + struct lockdep_map *lockdep_map; #endif char name[WQ_NAME_LEN]; /* I: workqueue name */ + /* + * Destruction of workqueue_struct is RCU protected to allow walking + * the workqueues list without grabbing wq_pool_mutex. + * This is used to dump all workqueues from sysrq. + */ + struct rcu_head rcu; + /* hot fields used during command issue, aligned to cacheline */ unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */ - struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */ - struct pool_workqueue __rcu *numa_pwq_tbl[]; /* FR: unbound pwqs indexed by node */ + struct pool_workqueue __rcu * __percpu *cpu_pwq; /* I: per-cpu pwqs */ + struct wq_node_nr_active *node_nr_active[]; /* I: per-node nr_active */ }; -static struct kmem_cache *pwq_cache; +/* + * Each pod type describes how CPUs should be grouped for unbound workqueues. + * See the comment above workqueue_attrs->affn_scope. + */ +struct wq_pod_type { + int nr_pods; /* number of pods */ + cpumask_var_t *pod_cpus; /* pod -> cpus */ + int *pod_node; /* pod -> node */ + int *cpu_pod; /* cpu -> pod */ +}; -static int wq_numa_tbl_len; /* highest possible NUMA node id + 1 */ -static cpumask_var_t *wq_numa_possible_cpumask; - /* possible CPUs of each node */ +struct work_offq_data { + u32 pool_id; + u32 disable; + u32 flags; +}; -static bool wq_disable_numa; -module_param_named(disable_numa, wq_disable_numa, bool, 0444); +static const char *wq_affn_names[WQ_AFFN_NR_TYPES] = { + [WQ_AFFN_DFL] = "default", + [WQ_AFFN_CPU] = "cpu", + [WQ_AFFN_SMT] = "smt", + [WQ_AFFN_CACHE] = "cache", + [WQ_AFFN_NUMA] = "numa", + [WQ_AFFN_SYSTEM] = "system", +}; -/* see the comment above the definition of WQ_POWER_EFFICIENT */ -#ifdef CONFIG_WQ_POWER_EFFICIENT_DEFAULT -static bool wq_power_efficient = true; -#else -static bool wq_power_efficient; +/* + * Per-cpu work items which run for longer than the following threshold are + * automatically considered CPU intensive and excluded from concurrency + * management to prevent them from noticeably delaying other per-cpu work items. + * ULONG_MAX indicates that the user hasn't overridden it with a boot parameter. + * The actual value is initialized in wq_cpu_intensive_thresh_init(). + */ +static unsigned long wq_cpu_intensive_thresh_us = ULONG_MAX; +module_param_named(cpu_intensive_thresh_us, wq_cpu_intensive_thresh_us, ulong, 0644); +#ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT +static unsigned int wq_cpu_intensive_warning_thresh = 4; +module_param_named(cpu_intensive_warning_thresh, wq_cpu_intensive_warning_thresh, uint, 0644); #endif +/* see the comment above the definition of WQ_POWER_EFFICIENT */ +static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT); module_param_named(power_efficient, wq_power_efficient, bool, 0444); -static bool wq_numa_enabled; /* unbound NUMA affinity enabled */ +static bool wq_online; /* can kworkers be created yet? */ +static bool wq_topo_initialized __read_mostly = false; -/* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */ -static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf; +static struct kmem_cache *pwq_cache; + +static struct wq_pod_type wq_pod_types[WQ_AFFN_NR_TYPES]; +static enum wq_affn_scope wq_affn_dfl = WQ_AFFN_CACHE; + +/* buf for wq_update_unbound_pod_attrs(), protected by CPU hotplug exclusion */ +static struct workqueue_attrs *unbound_wq_update_pwq_attrs_buf; static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */ -static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ +static DEFINE_MUTEX(wq_pool_attach_mutex); /* protects worker attach/detach */ +static DEFINE_RAW_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ +/* wait for manager to go away */ +static struct rcuwait manager_wait = __RCUWAIT_INITIALIZER(manager_wait); -static LIST_HEAD(workqueues); /* PL: list of all workqueues */ +static LIST_HEAD(workqueues); /* PR: list of all workqueues */ static bool workqueue_freezing; /* PL: have wqs started freezing? */ +/* PL: mirror the cpu_online_mask excluding the CPU in the midst of hotplugging */ +static cpumask_var_t wq_online_cpumask; + +/* PL&A: allowable cpus for unbound wqs and work items */ +static cpumask_var_t wq_unbound_cpumask; + +/* PL: user requested unbound cpumask via sysfs */ +static cpumask_var_t wq_requested_unbound_cpumask; + +/* PL: isolated cpumask to be excluded from unbound cpumask */ +static cpumask_var_t wq_isolated_cpumask; + +/* for further constrain wq_unbound_cpumask by cmdline parameter*/ +static struct cpumask wq_cmdline_cpumask __initdata; + +/* CPU where unbound work was last round robin scheduled from this CPU */ +static DEFINE_PER_CPU(int, wq_rr_cpu_last); + +/* + * Local execution of unbound work items is no longer guaranteed. The + * following always forces round-robin CPU selection on unbound work items + * to uncover usages which depend on it. + */ +#ifdef CONFIG_DEBUG_WQ_FORCE_RR_CPU +static bool wq_debug_force_rr_cpu = true; +#else +static bool wq_debug_force_rr_cpu = false; +#endif +module_param_named(debug_force_rr_cpu, wq_debug_force_rr_cpu, bool, 0644); + +/* to raise softirq for the BH worker pools on other CPUs */ +static DEFINE_PER_CPU_SHARED_ALIGNED(struct irq_work [NR_STD_WORKER_POOLS], bh_pool_irq_works); + +/* the BH worker pools */ +static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], bh_worker_pools); + /* the per-cpu worker pools */ -static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], - cpu_worker_pools); +static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], cpu_worker_pools); static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */ @@ -304,47 +495,56 @@ static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER); /* I: attributes used when instantiating standard unbound pools on demand */ static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS]; -struct workqueue_struct *system_wq __read_mostly; +/* I: attributes used when instantiating ordered pools on demand */ +static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS]; + +/* + * I: kthread_worker to release pwq's. pwq release needs to be bounced to a + * process context while holding a pool lock. Bounce to a dedicated kthread + * worker to avoid A-A deadlocks. + */ +static struct kthread_worker *pwq_release_worker __ro_after_init; + +struct workqueue_struct *system_wq __ro_after_init; EXPORT_SYMBOL(system_wq); -struct workqueue_struct *system_highpri_wq __read_mostly; +struct workqueue_struct *system_percpu_wq __ro_after_init; +EXPORT_SYMBOL(system_percpu_wq); +struct workqueue_struct *system_highpri_wq __ro_after_init; EXPORT_SYMBOL_GPL(system_highpri_wq); -struct workqueue_struct *system_long_wq __read_mostly; +struct workqueue_struct *system_long_wq __ro_after_init; EXPORT_SYMBOL_GPL(system_long_wq); -struct workqueue_struct *system_unbound_wq __read_mostly; +struct workqueue_struct *system_unbound_wq __ro_after_init; EXPORT_SYMBOL_GPL(system_unbound_wq); -struct workqueue_struct *system_freezable_wq __read_mostly; +struct workqueue_struct *system_dfl_wq __ro_after_init; +EXPORT_SYMBOL_GPL(system_dfl_wq); +struct workqueue_struct *system_freezable_wq __ro_after_init; EXPORT_SYMBOL_GPL(system_freezable_wq); -struct workqueue_struct *system_power_efficient_wq __read_mostly; +struct workqueue_struct *system_power_efficient_wq __ro_after_init; EXPORT_SYMBOL_GPL(system_power_efficient_wq); -struct workqueue_struct *system_freezable_power_efficient_wq __read_mostly; +struct workqueue_struct *system_freezable_power_efficient_wq __ro_after_init; EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq); +struct workqueue_struct *system_bh_wq; +EXPORT_SYMBOL_GPL(system_bh_wq); +struct workqueue_struct *system_bh_highpri_wq; +EXPORT_SYMBOL_GPL(system_bh_highpri_wq); static int worker_thread(void *__worker); -static void copy_workqueue_attrs(struct workqueue_attrs *to, - const struct workqueue_attrs *from); +static void workqueue_sysfs_unregister(struct workqueue_struct *wq); +static void show_pwq(struct pool_workqueue *pwq); +static void show_one_worker_pool(struct worker_pool *pool); #define CREATE_TRACE_POINTS #include <trace/events/workqueue.h> #define assert_rcu_or_pool_mutex() \ - rcu_lockdep_assert(rcu_read_lock_sched_held() || \ - lockdep_is_held(&wq_pool_mutex), \ - "sched RCU or wq_pool_mutex should be held") - -#define assert_rcu_or_wq_mutex(wq) \ - rcu_lockdep_assert(rcu_read_lock_sched_held() || \ - lockdep_is_held(&wq->mutex), \ - "sched RCU or wq->mutex should be held") + RCU_LOCKDEP_WARN(!rcu_read_lock_any_held() && \ + !lockdep_is_held(&wq_pool_mutex), \ + "RCU or wq_pool_mutex should be held") -#ifdef CONFIG_LOCKDEP -#define assert_manager_or_pool_lock(pool) \ - WARN_ONCE(debug_locks && \ - !lockdep_is_held(&(pool)->manager_mutex) && \ - !lockdep_is_held(&(pool)->lock), \ - "pool->manager_mutex or ->lock should be held") -#else -#define assert_manager_or_pool_lock(pool) do { } while (0) -#endif +#define for_each_bh_worker_pool(pool, cpu) \ + for ((pool) = &per_cpu(bh_worker_pools, cpu)[0]; \ + (pool) < &per_cpu(bh_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \ + (pool)++) #define for_each_cpu_worker_pool(pool, cpu) \ for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \ @@ -356,7 +556,7 @@ static void copy_workqueue_attrs(struct workqueue_attrs *to, * @pool: iteration cursor * @pi: integer used for iteration * - * This must be called either with wq_pool_mutex held or sched RCU read + * This must be called either with wq_pool_mutex held or RCU read * locked. If the pool needs to be used beyond the locking in effect, the * caller is responsible for guaranteeing that the pool stays online. * @@ -371,17 +571,16 @@ static void copy_workqueue_attrs(struct workqueue_attrs *to, /** * for_each_pool_worker - iterate through all workers of a worker_pool * @worker: iteration cursor - * @wi: integer used for iteration * @pool: worker_pool to iterate workers of * - * This must be called with either @pool->manager_mutex or ->lock held. + * This must be called with wq_pool_attach_mutex. * * The if/else clause exists only for the lockdep assertion and can be * ignored. */ -#define for_each_pool_worker(worker, wi, pool) \ - idr_for_each_entry(&(pool)->worker_idr, (worker), (wi)) \ - if (({ assert_manager_or_pool_lock((pool)); false; })) { } \ +#define for_each_pool_worker(worker, pool) \ + list_for_each_entry((worker), &(pool)->workers, node) \ + if (({ lockdep_assert_held(&wq_pool_attach_mutex); false; })) { } \ else /** @@ -389,7 +588,7 @@ static void copy_workqueue_attrs(struct workqueue_attrs *to, * @pwq: iteration cursor * @wq: the target workqueue * - * This must be called either with wq->mutex held or sched RCU read locked. + * This must be called either with wq->mutex held or RCU read locked. * If the pwq needs to be used beyond the locking in effect, the caller is * responsible for guaranteeing that the pwq stays online. * @@ -397,67 +596,40 @@ static void copy_workqueue_attrs(struct workqueue_attrs *to, * ignored. */ #define for_each_pwq(pwq, wq) \ - list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \ - if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \ - else + list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node, \ + lockdep_is_held(&(wq->mutex))) #ifdef CONFIG_DEBUG_OBJECTS_WORK -static struct debug_obj_descr work_debug_descr; +static const struct debug_obj_descr work_debug_descr; static void *work_debug_hint(void *addr) { return ((struct work_struct *) addr)->func; } -/* - * fixup_init is called when: - * - an active object is initialized - */ -static int work_fixup_init(void *addr, enum debug_obj_state state) +static bool work_is_static_object(void *addr) { struct work_struct *work = addr; - switch (state) { - case ODEBUG_STATE_ACTIVE: - cancel_work_sync(work); - debug_object_init(work, &work_debug_descr); - return 1; - default: - return 0; - } + return test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work)); } /* - * fixup_activate is called when: - * - an active object is activated - * - an unknown object is activated (might be a statically initialized object) + * fixup_init is called when: + * - an active object is initialized */ -static int work_fixup_activate(void *addr, enum debug_obj_state state) +static bool work_fixup_init(void *addr, enum debug_obj_state state) { struct work_struct *work = addr; switch (state) { - - case ODEBUG_STATE_NOTAVAILABLE: - /* - * This is not really a fixup. The work struct was - * statically initialized. We just make sure that it - * is tracked in the object tracker. - */ - if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { - debug_object_init(work, &work_debug_descr); - debug_object_activate(work, &work_debug_descr); - return 0; - } - WARN_ON_ONCE(1); - return 0; - case ODEBUG_STATE_ACTIVE: - WARN_ON(1); - + cancel_work_sync(work); + debug_object_init(work, &work_debug_descr); + return true; default: - return 0; + return false; } } @@ -465,7 +637,7 @@ static int work_fixup_activate(void *addr, enum debug_obj_state state) * fixup_free is called when: * - an active object is freed */ -static int work_fixup_free(void *addr, enum debug_obj_state state) +static bool work_fixup_free(void *addr, enum debug_obj_state state) { struct work_struct *work = addr; @@ -473,17 +645,17 @@ static int work_fixup_free(void *addr, enum debug_obj_state state) case ODEBUG_STATE_ACTIVE: cancel_work_sync(work); debug_object_free(work, &work_debug_descr); - return 1; + return true; default: - return 0; + return false; } } -static struct debug_obj_descr work_debug_descr = { +static const struct debug_obj_descr work_debug_descr = { .name = "work_struct", .debug_hint = work_debug_hint, + .is_static_object = work_is_static_object, .fixup_init = work_fixup_init, - .fixup_activate = work_fixup_activate, .fixup_free = work_fixup_free, }; @@ -512,19 +684,33 @@ void destroy_work_on_stack(struct work_struct *work) } EXPORT_SYMBOL_GPL(destroy_work_on_stack); +void destroy_delayed_work_on_stack(struct delayed_work *work) +{ + timer_destroy_on_stack(&work->timer); + debug_object_free(&work->work, &work_debug_descr); +} +EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack); + #else static inline void debug_work_activate(struct work_struct *work) { } static inline void debug_work_deactivate(struct work_struct *work) { } #endif -/* allocate ID and assign it to @pool */ +/** + * worker_pool_assign_id - allocate ID and assign it to @pool + * @pool: the pool pointer of interest + * + * Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned + * successfully, -errno on failure. + */ static int worker_pool_assign_id(struct worker_pool *pool) { int ret; lockdep_assert_held(&wq_pool_mutex); - ret = idr_alloc(&worker_pool_idr, pool, 0, 0, GFP_KERNEL); + ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE, + GFP_KERNEL); if (ret >= 0) { pool->id = ret; return 0; @@ -532,20 +718,34 @@ static int worker_pool_assign_id(struct worker_pool *pool) return ret; } +static struct pool_workqueue __rcu ** +unbound_pwq_slot(struct workqueue_struct *wq, int cpu) +{ + if (cpu >= 0) + return per_cpu_ptr(wq->cpu_pwq, cpu); + else + return &wq->dfl_pwq; +} + +/* @cpu < 0 for dfl_pwq */ +static struct pool_workqueue *unbound_pwq(struct workqueue_struct *wq, int cpu) +{ + return rcu_dereference_check(*unbound_pwq_slot(wq, cpu), + lockdep_is_held(&wq_pool_mutex) || + lockdep_is_held(&wq->mutex)); +} + /** - * unbound_pwq_by_node - return the unbound pool_workqueue for the given node - * @wq: the target workqueue - * @node: the node ID + * unbound_effective_cpumask - effective cpumask of an unbound workqueue + * @wq: workqueue of interest * - * This must be called either with pwq_lock held or sched RCU read locked. - * If the pwq needs to be used beyond the locking in effect, the caller is - * responsible for guaranteeing that the pwq stays online. + * @wq->unbound_attrs->cpumask contains the cpumask requested by the user which + * is masked with wq_unbound_cpumask to determine the effective cpumask. The + * default pwq is always mapped to the pool with the current effective cpumask. */ -static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq, - int node) +static struct cpumask *unbound_effective_cpumask(struct workqueue_struct *wq) { - assert_rcu_or_wq_mutex(wq); - return rcu_dereference_raw(wq->numa_pwq_tbl[node]); + return unbound_pwq(wq, -1)->pool->attrs->__pod_cpumask; } static unsigned int work_color_to_flags(int color) @@ -553,9 +753,9 @@ static unsigned int work_color_to_flags(int color) return color << WORK_STRUCT_COLOR_SHIFT; } -static int get_work_color(struct work_struct *work) +static int get_work_color(unsigned long work_data) { - return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & + return (work_data >> WORK_STRUCT_COLOR_SHIFT) & ((1 << WORK_STRUCT_COLOR_BITS) - 1); } @@ -564,49 +764,47 @@ static int work_next_color(int color) return (color + 1) % WORK_NR_COLORS; } +static unsigned long pool_offq_flags(struct worker_pool *pool) +{ + return (pool->flags & POOL_BH) ? WORK_OFFQ_BH : 0; +} + /* * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data * contain the pointer to the queued pwq. Once execution starts, the flag * is cleared and the high bits contain OFFQ flags and pool ID. * - * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling() - * and clear_work_data() can be used to set the pwq, pool or clear - * work->data. These functions should only be called while the work is - * owned - ie. while the PENDING bit is set. + * set_work_pwq(), set_work_pool_and_clear_pending() and mark_work_canceling() + * can be used to set the pwq, pool or clear work->data. These functions should + * only be called while the work is owned - ie. while the PENDING bit is set. * * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq * corresponding to a work. Pool is available once the work has been * queued anywhere after initialization until it is sync canceled. pwq is * available only while the work item is queued. - * - * %WORK_OFFQ_CANCELING is used to mark a work item which is being - * canceled. While being canceled, a work item may have its PENDING set - * but stay off timer and worklist for arbitrarily long and nobody should - * try to steal the PENDING bit. */ -static inline void set_work_data(struct work_struct *work, unsigned long data, - unsigned long flags) +static inline void set_work_data(struct work_struct *work, unsigned long data) { WARN_ON_ONCE(!work_pending(work)); - atomic_long_set(&work->data, data | flags | work_static(work)); + atomic_long_set(&work->data, data | work_static(work)); } static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq, - unsigned long extra_flags) + unsigned long flags) { - set_work_data(work, (unsigned long)pwq, - WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags); + set_work_data(work, (unsigned long)pwq | WORK_STRUCT_PENDING | + WORK_STRUCT_PWQ | flags); } static void set_work_pool_and_keep_pending(struct work_struct *work, - int pool_id) + int pool_id, unsigned long flags) { - set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, - WORK_STRUCT_PENDING); + set_work_data(work, ((unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT) | + WORK_STRUCT_PENDING | flags); } static void set_work_pool_and_clear_pending(struct work_struct *work, - int pool_id) + int pool_id, unsigned long flags) { /* * The following wmb is paired with the implied mb in @@ -615,13 +813,42 @@ static void set_work_pool_and_clear_pending(struct work_struct *work, * owner. */ smp_wmb(); - set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0); + set_work_data(work, ((unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT) | + flags); + /* + * The following mb guarantees that previous clear of a PENDING bit + * will not be reordered with any speculative LOADS or STORES from + * work->current_func, which is executed afterwards. This possible + * reordering can lead to a missed execution on attempt to queue + * the same @work. E.g. consider this case: + * + * CPU#0 CPU#1 + * ---------------------------- -------------------------------- + * + * 1 STORE event_indicated + * 2 queue_work_on() { + * 3 test_and_set_bit(PENDING) + * 4 } set_..._and_clear_pending() { + * 5 set_work_data() # clear bit + * 6 smp_mb() + * 7 work->current_func() { + * 8 LOAD event_indicated + * } + * + * Without an explicit full barrier speculative LOAD on line 8 can + * be executed before CPU#0 does STORE on line 1. If that happens, + * CPU#0 observes the PENDING bit is still set and new execution of + * a @work is not queued in a hope, that CPU#1 will eventually + * finish the queued @work. Meanwhile CPU#1 does not see + * event_indicated is set, because speculative LOAD was executed + * before actual STORE. + */ + smp_mb(); } -static void clear_work_data(struct work_struct *work) +static inline struct pool_workqueue *work_struct_pwq(unsigned long data) { - smp_wmb(); /* see set_work_pool_and_clear_pending() */ - set_work_data(work, WORK_STRUCT_NO_POOL, 0); + return (struct pool_workqueue *)(data & WORK_STRUCT_PWQ_MASK); } static struct pool_workqueue *get_work_pwq(struct work_struct *work) @@ -629,7 +856,7 @@ static struct pool_workqueue *get_work_pwq(struct work_struct *work) unsigned long data = atomic_long_read(&work->data); if (data & WORK_STRUCT_PWQ) - return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); + return work_struct_pwq(data); else return NULL; } @@ -638,16 +865,16 @@ static struct pool_workqueue *get_work_pwq(struct work_struct *work) * get_work_pool - return the worker_pool a given work was associated with * @work: the work item of interest * - * Return the worker_pool @work was last associated with. %NULL if none. - * * Pools are created and destroyed under wq_pool_mutex, and allows read - * access under sched-RCU read lock. As such, this function should be - * called under wq_pool_mutex or with preemption disabled. + * access under RCU read lock. As such, this function should be + * called under wq_pool_mutex or inside of a rcu_read_lock() region. * * All fields of the returned pool are accessible as long as the above * mentioned locking is in effect. If the returned pool needs to be used * beyond the critical section, the caller is responsible for ensuring the * returned pool is and stays online. + * + * Return: The worker_pool @work was last associated with. %NULL if none. */ static struct worker_pool *get_work_pool(struct work_struct *work) { @@ -657,8 +884,7 @@ static struct worker_pool *get_work_pool(struct work_struct *work) assert_rcu_or_pool_mutex(); if (data & WORK_STRUCT_PWQ) - return ((struct pool_workqueue *) - (data & WORK_STRUCT_WQ_DATA_MASK))->pool; + return work_struct_pwq(data)->pool; pool_id = data >> WORK_OFFQ_POOL_SHIFT; if (pool_id == WORK_OFFQ_POOL_NONE) @@ -667,37 +893,26 @@ static struct worker_pool *get_work_pool(struct work_struct *work) return idr_find(&worker_pool_idr, pool_id); } -/** - * get_work_pool_id - return the worker pool ID a given work is associated with - * @work: the work item of interest - * - * Return the worker_pool ID @work was last associated with. - * %WORK_OFFQ_POOL_NONE if none. - */ -static int get_work_pool_id(struct work_struct *work) +static unsigned long shift_and_mask(unsigned long v, u32 shift, u32 bits) { - unsigned long data = atomic_long_read(&work->data); - - if (data & WORK_STRUCT_PWQ) - return ((struct pool_workqueue *) - (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id; - - return data >> WORK_OFFQ_POOL_SHIFT; + return (v >> shift) & ((1U << bits) - 1); } -static void mark_work_canceling(struct work_struct *work) +static void work_offqd_unpack(struct work_offq_data *offqd, unsigned long data) { - unsigned long pool_id = get_work_pool_id(work); + WARN_ON_ONCE(data & WORK_STRUCT_PWQ); - pool_id <<= WORK_OFFQ_POOL_SHIFT; - set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING); + offqd->pool_id = shift_and_mask(data, WORK_OFFQ_POOL_SHIFT, + WORK_OFFQ_POOL_BITS); + offqd->disable = shift_and_mask(data, WORK_OFFQ_DISABLE_SHIFT, + WORK_OFFQ_DISABLE_BITS); + offqd->flags = data & WORK_OFFQ_FLAG_MASK; } -static bool work_is_canceling(struct work_struct *work) +static unsigned long work_offqd_pack_flags(struct work_offq_data *offqd) { - unsigned long data = atomic_long_read(&work->data); - - return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING); + return ((unsigned long)offqd->disable << WORK_OFFQ_DISABLE_SHIFT) | + ((unsigned long)offqd->flags); } /* @@ -706,11 +921,6 @@ static bool work_is_canceling(struct work_struct *work) * they're being called with pool->lock held. */ -static bool __need_more_worker(struct worker_pool *pool) -{ - return !atomic_read(&pool->nr_running); -} - /* * Need to wake up a worker? Called from anything but currently * running workers. @@ -721,7 +931,7 @@ static bool __need_more_worker(struct worker_pool *pool) */ static bool need_more_worker(struct worker_pool *pool) { - return !list_empty(&pool->worklist) && __need_more_worker(pool); + return !list_empty(&pool->worklist) && !pool->nr_running; } /* Can I start working? Called from busy but !running workers. */ @@ -733,8 +943,7 @@ static bool may_start_working(struct worker_pool *pool) /* Do I need to keep working? Called from currently running workers. */ static bool keep_working(struct worker_pool *pool) { - return !list_empty(&pool->worklist) && - atomic_read(&pool->nr_running) <= 1; + return !list_empty(&pool->worklist) && (pool->nr_running <= 1); } /* Do we need a new worker? Called from manager. */ @@ -743,165 +952,33 @@ static bool need_to_create_worker(struct worker_pool *pool) return need_more_worker(pool) && !may_start_working(pool); } -/* Do I need to be the manager? */ -static bool need_to_manage_workers(struct worker_pool *pool) -{ - return need_to_create_worker(pool) || - (pool->flags & POOL_MANAGE_WORKERS); -} - /* Do we have too many workers and should some go away? */ static bool too_many_workers(struct worker_pool *pool) { - bool managing = mutex_is_locked(&pool->manager_arb); + bool managing = pool->flags & POOL_MANAGER_ACTIVE; int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ int nr_busy = pool->nr_workers - nr_idle; - /* - * nr_idle and idle_list may disagree if idle rebinding is in - * progress. Never return %true if idle_list is empty. - */ - if (list_empty(&pool->idle_list)) - return false; - return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; } -/* - * Wake up functions. - */ - -/* Return the first worker. Safe with preemption disabled */ -static struct worker *first_worker(struct worker_pool *pool) -{ - if (unlikely(list_empty(&pool->idle_list))) - return NULL; - - return list_first_entry(&pool->idle_list, struct worker, entry); -} - -/** - * wake_up_worker - wake up an idle worker - * @pool: worker pool to wake worker from - * - * Wake up the first idle worker of @pool. - * - * CONTEXT: - * spin_lock_irq(pool->lock). - */ -static void wake_up_worker(struct worker_pool *pool) -{ - struct worker *worker = first_worker(pool); - - if (likely(worker)) - wake_up_process(worker->task); -} - -/** - * wq_worker_waking_up - a worker is waking up - * @task: task waking up - * @cpu: CPU @task is waking up to - * - * This function is called during try_to_wake_up() when a worker is - * being awoken. - * - * CONTEXT: - * spin_lock_irq(rq->lock) - */ -void wq_worker_waking_up(struct task_struct *task, int cpu) -{ - struct worker *worker = kthread_data(task); - - if (!(worker->flags & WORKER_NOT_RUNNING)) { - WARN_ON_ONCE(worker->pool->cpu != cpu); - atomic_inc(&worker->pool->nr_running); - } -} - -/** - * wq_worker_sleeping - a worker is going to sleep - * @task: task going to sleep - * @cpu: CPU in question, must be the current CPU number - * - * This function is called during schedule() when a busy worker is - * going to sleep. Worker on the same cpu can be woken up by - * returning pointer to its task. - * - * CONTEXT: - * spin_lock_irq(rq->lock) - * - * RETURNS: - * Worker task on @cpu to wake up, %NULL if none. - */ -struct task_struct *wq_worker_sleeping(struct task_struct *task, int cpu) -{ - struct worker *worker = kthread_data(task), *to_wakeup = NULL; - struct worker_pool *pool; - - /* - * Rescuers, which may not have all the fields set up like normal - * workers, also reach here, let's not access anything before - * checking NOT_RUNNING. - */ - if (worker->flags & WORKER_NOT_RUNNING) - return NULL; - - pool = worker->pool; - - /* this can only happen on the local cpu */ - if (WARN_ON_ONCE(cpu != raw_smp_processor_id())) - return NULL; - - /* - * The counterpart of the following dec_and_test, implied mb, - * worklist not empty test sequence is in insert_work(). - * Please read comment there. - * - * NOT_RUNNING is clear. This means that we're bound to and - * running on the local cpu w/ rq lock held and preemption - * disabled, which in turn means that none else could be - * manipulating idle_list, so dereferencing idle_list without pool - * lock is safe. - */ - if (atomic_dec_and_test(&pool->nr_running) && - !list_empty(&pool->worklist)) - to_wakeup = first_worker(pool); - return to_wakeup ? to_wakeup->task : NULL; -} - /** * worker_set_flags - set worker flags and adjust nr_running accordingly * @worker: self * @flags: flags to set - * @wakeup: wakeup an idle worker if necessary * - * Set @flags in @worker->flags and adjust nr_running accordingly. If - * nr_running becomes zero and @wakeup is %true, an idle worker is - * woken up. - * - * CONTEXT: - * spin_lock_irq(pool->lock) + * Set @flags in @worker->flags and adjust nr_running accordingly. */ -static inline void worker_set_flags(struct worker *worker, unsigned int flags, - bool wakeup) +static inline void worker_set_flags(struct worker *worker, unsigned int flags) { struct worker_pool *pool = worker->pool; - WARN_ON_ONCE(worker->task != current); + lockdep_assert_held(&pool->lock); - /* - * If transitioning into NOT_RUNNING, adjust nr_running and - * wake up an idle worker as necessary if requested by - * @wakeup. - */ + /* If transitioning into NOT_RUNNING, adjust nr_running. */ if ((flags & WORKER_NOT_RUNNING) && !(worker->flags & WORKER_NOT_RUNNING)) { - if (wakeup) { - if (atomic_dec_and_test(&pool->nr_running) && - !list_empty(&pool->worklist)) - wake_up_worker(pool); - } else - atomic_dec(&pool->nr_running); + pool->nr_running--; } worker->flags |= flags; @@ -913,16 +990,13 @@ static inline void worker_set_flags(struct worker *worker, unsigned int flags, * @flags: flags to clear * * Clear @flags in @worker->flags and adjust nr_running accordingly. - * - * CONTEXT: - * spin_lock_irq(pool->lock) */ static inline void worker_clr_flags(struct worker *worker, unsigned int flags) { struct worker_pool *pool = worker->pool; unsigned int oflags = worker->flags; - WARN_ON_ONCE(worker->task != current); + lockdep_assert_held(&pool->lock); worker->flags &= ~flags; @@ -933,7 +1007,70 @@ static inline void worker_clr_flags(struct worker *worker, unsigned int flags) */ if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) if (!(worker->flags & WORKER_NOT_RUNNING)) - atomic_inc(&pool->nr_running); + pool->nr_running++; +} + +/* Return the first idle worker. Called with pool->lock held. */ +static struct worker *first_idle_worker(struct worker_pool *pool) +{ + if (unlikely(list_empty(&pool->idle_list))) + return NULL; + + return list_first_entry(&pool->idle_list, struct worker, entry); +} + +/** + * worker_enter_idle - enter idle state + * @worker: worker which is entering idle state + * + * @worker is entering idle state. Update stats and idle timer if + * necessary. + * + * LOCKING: + * raw_spin_lock_irq(pool->lock). + */ +static void worker_enter_idle(struct worker *worker) +{ + struct worker_pool *pool = worker->pool; + + if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || + WARN_ON_ONCE(!list_empty(&worker->entry) && + (worker->hentry.next || worker->hentry.pprev))) + return; + + /* can't use worker_set_flags(), also called from create_worker() */ + worker->flags |= WORKER_IDLE; + pool->nr_idle++; + worker->last_active = jiffies; + + /* idle_list is LIFO */ + list_add(&worker->entry, &pool->idle_list); + + if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) + mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); + + /* Sanity check nr_running. */ + WARN_ON_ONCE(pool->nr_workers == pool->nr_idle && pool->nr_running); +} + +/** + * worker_leave_idle - leave idle state + * @worker: worker which is leaving idle state + * + * @worker is leaving idle state. Update stats. + * + * LOCKING: + * raw_spin_lock_irq(pool->lock). + */ +static void worker_leave_idle(struct worker *worker) +{ + struct worker_pool *pool = worker->pool; + + if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) + return; + worker_clr_flags(worker, WORKER_IDLE); + pool->nr_idle--; + list_del_init(&worker->entry); } /** @@ -963,10 +1100,10 @@ static inline void worker_clr_flags(struct worker *worker, unsigned int flags) * actually occurs, it should be easy to locate the culprit work function. * * CONTEXT: - * spin_lock_irq(pool->lock). + * raw_spin_lock_irq(pool->lock). * - * RETURNS: - * Pointer to worker which is executing @work if found, NULL + * Return: + * Pointer to worker which is executing @work if found, %NULL * otherwise. */ static struct worker *find_worker_executing_work(struct worker_pool *pool, @@ -987,18 +1124,15 @@ static struct worker *find_worker_executing_work(struct worker_pool *pool, * move_linked_works - move linked works to a list * @work: start of series of works to be scheduled * @head: target list to append @work to - * @nextp: out paramter for nested worklist walking - * - * Schedule linked works starting from @work to @head. Work series to - * be scheduled starts at @work and includes any consecutive work with - * WORK_STRUCT_LINKED set in its predecessor. + * @nextp: out parameter for nested worklist walking * - * If @nextp is not NULL, it's updated to point to the next work of - * the last scheduled work. This allows move_linked_works() to be - * nested inside outer list_for_each_entry_safe(). + * Schedule linked works starting from @work to @head. Work series to be + * scheduled starts at @work and includes any consecutive work with + * WORK_STRUCT_LINKED set in its predecessor. See assign_work() for details on + * @nextp. * * CONTEXT: - * spin_lock_irq(pool->lock). + * raw_spin_lock_irq(pool->lock). */ static void move_linked_works(struct work_struct *work, struct list_head *head, struct work_struct **nextp) @@ -1025,6 +1159,461 @@ static void move_linked_works(struct work_struct *work, struct list_head *head, } /** + * assign_work - assign a work item and its linked work items to a worker + * @work: work to assign + * @worker: worker to assign to + * @nextp: out parameter for nested worklist walking + * + * Assign @work and its linked work items to @worker. If @work is already being + * executed by another worker in the same pool, it'll be punted there. + * + * If @nextp is not NULL, it's updated to point to the next work of the last + * scheduled work. This allows assign_work() to be nested inside + * list_for_each_entry_safe(). + * + * Returns %true if @work was successfully assigned to @worker. %false if @work + * was punted to another worker already executing it. + */ +static bool assign_work(struct work_struct *work, struct worker *worker, + struct work_struct **nextp) +{ + struct worker_pool *pool = worker->pool; + struct worker *collision; + + lockdep_assert_held(&pool->lock); + + /* + * A single work shouldn't be executed concurrently by multiple workers. + * __queue_work() ensures that @work doesn't jump to a different pool + * while still running in the previous pool. Here, we should ensure that + * @work is not executed concurrently by multiple workers from the same + * pool. Check whether anyone is already processing the work. If so, + * defer the work to the currently executing one. + */ + collision = find_worker_executing_work(pool, work); + if (unlikely(collision)) { + move_linked_works(work, &collision->scheduled, nextp); + return false; + } + + move_linked_works(work, &worker->scheduled, nextp); + return true; +} + +static struct irq_work *bh_pool_irq_work(struct worker_pool *pool) +{ + int high = pool->attrs->nice == HIGHPRI_NICE_LEVEL ? 1 : 0; + + return &per_cpu(bh_pool_irq_works, pool->cpu)[high]; +} + +static void kick_bh_pool(struct worker_pool *pool) +{ +#ifdef CONFIG_SMP + /* see drain_dead_softirq_workfn() for BH_DRAINING */ + if (unlikely(pool->cpu != smp_processor_id() && + !(pool->flags & POOL_BH_DRAINING))) { + irq_work_queue_on(bh_pool_irq_work(pool), pool->cpu); + return; + } +#endif + if (pool->attrs->nice == HIGHPRI_NICE_LEVEL) + raise_softirq_irqoff(HI_SOFTIRQ); + else + raise_softirq_irqoff(TASKLET_SOFTIRQ); +} + +/** + * kick_pool - wake up an idle worker if necessary + * @pool: pool to kick + * + * @pool may have pending work items. Wake up worker if necessary. Returns + * whether a worker was woken up. + */ +static bool kick_pool(struct worker_pool *pool) +{ + struct worker *worker = first_idle_worker(pool); + struct task_struct *p; + + lockdep_assert_held(&pool->lock); + + if (!need_more_worker(pool) || !worker) + return false; + + if (pool->flags & POOL_BH) { + kick_bh_pool(pool); + return true; + } + + p = worker->task; + +#ifdef CONFIG_SMP + /* + * Idle @worker is about to execute @work and waking up provides an + * opportunity to migrate @worker at a lower cost by setting the task's + * wake_cpu field. Let's see if we want to move @worker to improve + * execution locality. + * + * We're waking the worker that went idle the latest and there's some + * chance that @worker is marked idle but hasn't gone off CPU yet. If + * so, setting the wake_cpu won't do anything. As this is a best-effort + * optimization and the race window is narrow, let's leave as-is for + * now. If this becomes pronounced, we can skip over workers which are + * still on cpu when picking an idle worker. + * + * If @pool has non-strict affinity, @worker might have ended up outside + * its affinity scope. Repatriate. + */ + if (!pool->attrs->affn_strict && + !cpumask_test_cpu(p->wake_cpu, pool->attrs->__pod_cpumask)) { + struct work_struct *work = list_first_entry(&pool->worklist, + struct work_struct, entry); + int wake_cpu = cpumask_any_and_distribute(pool->attrs->__pod_cpumask, + cpu_online_mask); + if (wake_cpu < nr_cpu_ids) { + p->wake_cpu = wake_cpu; + get_work_pwq(work)->stats[PWQ_STAT_REPATRIATED]++; + } + } +#endif + wake_up_process(p); + return true; +} + +#ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT + +/* + * Concurrency-managed per-cpu work items that hog CPU for longer than + * wq_cpu_intensive_thresh_us trigger the automatic CPU_INTENSIVE mechanism, + * which prevents them from stalling other concurrency-managed work items. If a + * work function keeps triggering this mechanism, it's likely that the work item + * should be using an unbound workqueue instead. + * + * wq_cpu_intensive_report() tracks work functions which trigger such conditions + * and report them so that they can be examined and converted to use unbound + * workqueues as appropriate. To avoid flooding the console, each violating work + * function is tracked and reported with exponential backoff. + */ +#define WCI_MAX_ENTS 128 + +struct wci_ent { + work_func_t func; + atomic64_t cnt; + struct hlist_node hash_node; +}; + +static struct wci_ent wci_ents[WCI_MAX_ENTS]; +static int wci_nr_ents; +static DEFINE_RAW_SPINLOCK(wci_lock); +static DEFINE_HASHTABLE(wci_hash, ilog2(WCI_MAX_ENTS)); + +static struct wci_ent *wci_find_ent(work_func_t func) +{ + struct wci_ent *ent; + + hash_for_each_possible_rcu(wci_hash, ent, hash_node, + (unsigned long)func) { + if (ent->func == func) + return ent; + } + return NULL; +} + +static void wq_cpu_intensive_report(work_func_t func) +{ + struct wci_ent *ent; + +restart: + ent = wci_find_ent(func); + if (ent) { + u64 cnt; + + /* + * Start reporting from the warning_thresh and back off + * exponentially. + */ + cnt = atomic64_inc_return_relaxed(&ent->cnt); + if (wq_cpu_intensive_warning_thresh && + cnt >= wq_cpu_intensive_warning_thresh && + is_power_of_2(cnt + 1 - wq_cpu_intensive_warning_thresh)) + printk_deferred(KERN_WARNING "workqueue: %ps hogged CPU for >%luus %llu times, consider switching to WQ_UNBOUND\n", + ent->func, wq_cpu_intensive_thresh_us, + atomic64_read(&ent->cnt)); + return; + } + + /* + * @func is a new violation. Allocate a new entry for it. If wcn_ents[] + * is exhausted, something went really wrong and we probably made enough + * noise already. + */ + if (wci_nr_ents >= WCI_MAX_ENTS) + return; + + raw_spin_lock(&wci_lock); + + if (wci_nr_ents >= WCI_MAX_ENTS) { + raw_spin_unlock(&wci_lock); + return; + } + + if (wci_find_ent(func)) { + raw_spin_unlock(&wci_lock); + goto restart; + } + + ent = &wci_ents[wci_nr_ents++]; + ent->func = func; + atomic64_set(&ent->cnt, 0); + hash_add_rcu(wci_hash, &ent->hash_node, (unsigned long)func); + + raw_spin_unlock(&wci_lock); + + goto restart; +} + +#else /* CONFIG_WQ_CPU_INTENSIVE_REPORT */ +static void wq_cpu_intensive_report(work_func_t func) {} +#endif /* CONFIG_WQ_CPU_INTENSIVE_REPORT */ + +/** + * wq_worker_running - a worker is running again + * @task: task waking up + * + * This function is called when a worker returns from schedule() + */ +void wq_worker_running(struct task_struct *task) +{ + struct worker *worker = kthread_data(task); + + if (!READ_ONCE(worker->sleeping)) + return; + + /* + * If preempted by unbind_workers() between the WORKER_NOT_RUNNING check + * and the nr_running increment below, we may ruin the nr_running reset + * and leave with an unexpected pool->nr_running == 1 on the newly unbound + * pool. Protect against such race. + */ + preempt_disable(); + if (!(worker->flags & WORKER_NOT_RUNNING)) + worker->pool->nr_running++; + preempt_enable(); + + /* + * CPU intensive auto-detection cares about how long a work item hogged + * CPU without sleeping. Reset the starting timestamp on wakeup. + */ + worker->current_at = worker->task->se.sum_exec_runtime; + + WRITE_ONCE(worker->sleeping, 0); +} + +/** + * wq_worker_sleeping - a worker is going to sleep + * @task: task going to sleep + * + * This function is called from schedule() when a busy worker is + * going to sleep. + */ +void wq_worker_sleeping(struct task_struct *task) +{ + struct worker *worker = kthread_data(task); + struct worker_pool *pool; + + /* + * Rescuers, which may not have all the fields set up like normal + * workers, also reach here, let's not access anything before + * checking NOT_RUNNING. + */ + if (worker->flags & WORKER_NOT_RUNNING) + return; + + pool = worker->pool; + + /* Return if preempted before wq_worker_running() was reached */ + if (READ_ONCE(worker->sleeping)) + return; + + WRITE_ONCE(worker->sleeping, 1); + raw_spin_lock_irq(&pool->lock); + + /* + * Recheck in case unbind_workers() preempted us. We don't + * want to decrement nr_running after the worker is unbound + * and nr_running has been reset. + */ + if (worker->flags & WORKER_NOT_RUNNING) { + raw_spin_unlock_irq(&pool->lock); + return; + } + + pool->nr_running--; + if (kick_pool(pool)) + worker->current_pwq->stats[PWQ_STAT_CM_WAKEUP]++; + + raw_spin_unlock_irq(&pool->lock); +} + +/** + * wq_worker_tick - a scheduler tick occurred while a kworker is running + * @task: task currently running + * + * Called from sched_tick(). We're in the IRQ context and the current + * worker's fields which follow the 'K' locking rule can be accessed safely. + */ +void wq_worker_tick(struct task_struct *task) +{ + struct worker *worker = kthread_data(task); + struct pool_workqueue *pwq = worker->current_pwq; + struct worker_pool *pool = worker->pool; + + if (!pwq) + return; + + pwq->stats[PWQ_STAT_CPU_TIME] += TICK_USEC; + + if (!wq_cpu_intensive_thresh_us) + return; + + /* + * If the current worker is concurrency managed and hogged the CPU for + * longer than wq_cpu_intensive_thresh_us, it's automatically marked + * CPU_INTENSIVE to avoid stalling other concurrency-managed work items. + * + * Set @worker->sleeping means that @worker is in the process of + * switching out voluntarily and won't be contributing to + * @pool->nr_running until it wakes up. As wq_worker_sleeping() also + * decrements ->nr_running, setting CPU_INTENSIVE here can lead to + * double decrements. The task is releasing the CPU anyway. Let's skip. + * We probably want to make this prettier in the future. + */ + if ((worker->flags & WORKER_NOT_RUNNING) || READ_ONCE(worker->sleeping) || + worker->task->se.sum_exec_runtime - worker->current_at < + wq_cpu_intensive_thresh_us * NSEC_PER_USEC) + return; + + raw_spin_lock(&pool->lock); + + worker_set_flags(worker, WORKER_CPU_INTENSIVE); + wq_cpu_intensive_report(worker->current_func); + pwq->stats[PWQ_STAT_CPU_INTENSIVE]++; + + if (kick_pool(pool)) + pwq->stats[PWQ_STAT_CM_WAKEUP]++; + + raw_spin_unlock(&pool->lock); +} + +/** + * wq_worker_last_func - retrieve worker's last work function + * @task: Task to retrieve last work function of. + * + * Determine the last function a worker executed. This is called from + * the scheduler to get a worker's last known identity. + * + * CONTEXT: + * raw_spin_lock_irq(rq->lock) + * + * This function is called during schedule() when a kworker is going + * to sleep. It's used by psi to identify aggregation workers during + * dequeuing, to allow periodic aggregation to shut-off when that + * worker is the last task in the system or cgroup to go to sleep. + * + * As this function doesn't involve any workqueue-related locking, it + * only returns stable values when called from inside the scheduler's + * queuing and dequeuing paths, when @task, which must be a kworker, + * is guaranteed to not be processing any works. + * + * Return: + * The last work function %current executed as a worker, NULL if it + * hasn't executed any work yet. + */ +work_func_t wq_worker_last_func(struct task_struct *task) +{ + struct worker *worker = kthread_data(task); + + return worker->last_func; +} + +/** + * wq_node_nr_active - Determine wq_node_nr_active to use + * @wq: workqueue of interest + * @node: NUMA node, can be %NUMA_NO_NODE + * + * Determine wq_node_nr_active to use for @wq on @node. Returns: + * + * - %NULL for per-cpu workqueues as they don't need to use shared nr_active. + * + * - node_nr_active[nr_node_ids] if @node is %NUMA_NO_NODE. + * + * - Otherwise, node_nr_active[@node]. + */ +static struct wq_node_nr_active *wq_node_nr_active(struct workqueue_struct *wq, + int node) +{ + if (!(wq->flags & WQ_UNBOUND)) + return NULL; + + if (node == NUMA_NO_NODE) + node = nr_node_ids; + + return wq->node_nr_active[node]; +} + +/** + * wq_update_node_max_active - Update per-node max_actives to use + * @wq: workqueue to update + * @off_cpu: CPU that's going down, -1 if a CPU is not going down + * + * Update @wq->node_nr_active[]->max. @wq must be unbound. max_active is + * distributed among nodes according to the proportions of numbers of online + * cpus. The result is always between @wq->min_active and max_active. + */ +static void wq_update_node_max_active(struct workqueue_struct *wq, int off_cpu) +{ + struct cpumask *effective = unbound_effective_cpumask(wq); + int min_active = READ_ONCE(wq->min_active); + int max_active = READ_ONCE(wq->max_active); + int total_cpus, node; + + lockdep_assert_held(&wq->mutex); + + if (!wq_topo_initialized) + return; + + if (off_cpu >= 0 && !cpumask_test_cpu(off_cpu, effective)) + off_cpu = -1; + + total_cpus = cpumask_weight_and(effective, cpu_online_mask); + if (off_cpu >= 0) + total_cpus--; + + /* If all CPUs of the wq get offline, use the default values */ + if (unlikely(!total_cpus)) { + for_each_node(node) + wq_node_nr_active(wq, node)->max = min_active; + + wq_node_nr_active(wq, NUMA_NO_NODE)->max = max_active; + return; + } + + for_each_node(node) { + int node_cpus; + + node_cpus = cpumask_weight_and(effective, cpumask_of_node(node)); + if (off_cpu >= 0 && cpu_to_node(off_cpu) == node) + node_cpus--; + + wq_node_nr_active(wq, node)->max = + clamp(DIV_ROUND_UP(max_active * node_cpus, total_cpus), + min_active, max_active); + } + + wq_node_nr_active(wq, NUMA_NO_NODE)->max = max_active; +} + +/** * get_pwq - get an extra reference on the specified pool_workqueue * @pwq: pool_workqueue to get * @@ -1050,17 +1639,11 @@ static void put_pwq(struct pool_workqueue *pwq) lockdep_assert_held(&pwq->pool->lock); if (likely(--pwq->refcnt)) return; - if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND))) - return; /* - * @pwq can't be released under pool->lock, bounce to - * pwq_unbound_release_workfn(). This never recurses on the same - * pool->lock as this path is taken only for unbound workqueues and - * the release work item is scheduled on a per-cpu workqueue. To - * avoid lockdep warning, unbound pool->locks are given lockdep - * subclass of 1 in get_unbound_pool(). + * @pwq can't be released under pool->lock, bounce to a dedicated + * kthread_worker to avoid A-A deadlocks. */ - schedule_work(&pwq->unbound_release_work); + kthread_queue_work(pwq_release_worker, &pwq->release_work); } /** @@ -1073,58 +1656,341 @@ static void put_pwq_unlocked(struct pool_workqueue *pwq) { if (pwq) { /* - * As both pwqs and pools are sched-RCU protected, the + * As both pwqs and pools are RCU protected, the * following lock operations are safe. */ - spin_lock_irq(&pwq->pool->lock); + raw_spin_lock_irq(&pwq->pool->lock); put_pwq(pwq); - spin_unlock_irq(&pwq->pool->lock); + raw_spin_unlock_irq(&pwq->pool->lock); } } -static void pwq_activate_delayed_work(struct work_struct *work) +static bool pwq_is_empty(struct pool_workqueue *pwq) { - struct pool_workqueue *pwq = get_work_pwq(work); + return !pwq->nr_active && list_empty(&pwq->inactive_works); +} +static void __pwq_activate_work(struct pool_workqueue *pwq, + struct work_struct *work) +{ + unsigned long *wdb = work_data_bits(work); + + WARN_ON_ONCE(!(*wdb & WORK_STRUCT_INACTIVE)); trace_workqueue_activate_work(work); + if (list_empty(&pwq->pool->worklist)) + pwq->pool->watchdog_ts = jiffies; move_linked_works(work, &pwq->pool->worklist, NULL); - __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); - pwq->nr_active++; + __clear_bit(WORK_STRUCT_INACTIVE_BIT, wdb); +} + +static bool tryinc_node_nr_active(struct wq_node_nr_active *nna) +{ + int max = READ_ONCE(nna->max); + int old = atomic_read(&nna->nr); + + do { + if (old >= max) + return false; + } while (!atomic_try_cmpxchg_relaxed(&nna->nr, &old, old + 1)); + + return true; +} + +/** + * pwq_tryinc_nr_active - Try to increment nr_active for a pwq + * @pwq: pool_workqueue of interest + * @fill: max_active may have increased, try to increase concurrency level + * + * Try to increment nr_active for @pwq. Returns %true if an nr_active count is + * successfully obtained. %false otherwise. + */ +static bool pwq_tryinc_nr_active(struct pool_workqueue *pwq, bool fill) +{ + struct workqueue_struct *wq = pwq->wq; + struct worker_pool *pool = pwq->pool; + struct wq_node_nr_active *nna = wq_node_nr_active(wq, pool->node); + bool obtained = false; + + lockdep_assert_held(&pool->lock); + + if (!nna) { + /* BH or per-cpu workqueue, pwq->nr_active is sufficient */ + obtained = pwq->nr_active < READ_ONCE(wq->max_active); + goto out; + } + + if (unlikely(pwq->plugged)) + return false; + + /* + * Unbound workqueue uses per-node shared nr_active $nna. If @pwq is + * already waiting on $nna, pwq_dec_nr_active() will maintain the + * concurrency level. Don't jump the line. + * + * We need to ignore the pending test after max_active has increased as + * pwq_dec_nr_active() can only maintain the concurrency level but not + * increase it. This is indicated by @fill. + */ + if (!list_empty(&pwq->pending_node) && likely(!fill)) + goto out; + + obtained = tryinc_node_nr_active(nna); + if (obtained) + goto out; + + /* + * Lockless acquisition failed. Lock, add ourself to $nna->pending_pwqs + * and try again. The smp_mb() is paired with the implied memory barrier + * of atomic_dec_return() in pwq_dec_nr_active() to ensure that either + * we see the decremented $nna->nr or they see non-empty + * $nna->pending_pwqs. + */ + raw_spin_lock(&nna->lock); + + if (list_empty(&pwq->pending_node)) + list_add_tail(&pwq->pending_node, &nna->pending_pwqs); + else if (likely(!fill)) + goto out_unlock; + + smp_mb(); + + obtained = tryinc_node_nr_active(nna); + + /* + * If @fill, @pwq might have already been pending. Being spuriously + * pending in cold paths doesn't affect anything. Let's leave it be. + */ + if (obtained && likely(!fill)) + list_del_init(&pwq->pending_node); + +out_unlock: + raw_spin_unlock(&nna->lock); +out: + if (obtained) + pwq->nr_active++; + return obtained; +} + +/** + * pwq_activate_first_inactive - Activate the first inactive work item on a pwq + * @pwq: pool_workqueue of interest + * @fill: max_active may have increased, try to increase concurrency level + * + * Activate the first inactive work item of @pwq if available and allowed by + * max_active limit. + * + * Returns %true if an inactive work item has been activated. %false if no + * inactive work item is found or max_active limit is reached. + */ +static bool pwq_activate_first_inactive(struct pool_workqueue *pwq, bool fill) +{ + struct work_struct *work = + list_first_entry_or_null(&pwq->inactive_works, + struct work_struct, entry); + + if (work && pwq_tryinc_nr_active(pwq, fill)) { + __pwq_activate_work(pwq, work); + return true; + } else { + return false; + } +} + +/** + * unplug_oldest_pwq - unplug the oldest pool_workqueue + * @wq: workqueue_struct where its oldest pwq is to be unplugged + * + * This function should only be called for ordered workqueues where only the + * oldest pwq is unplugged, the others are plugged to suspend execution to + * ensure proper work item ordering:: + * + * dfl_pwq --------------+ [P] - plugged + * | + * v + * pwqs -> A -> B [P] -> C [P] (newest) + * | | | + * 1 3 5 + * | | | + * 2 4 6 + * + * When the oldest pwq is drained and removed, this function should be called + * to unplug the next oldest one to start its work item execution. Note that + * pwq's are linked into wq->pwqs with the oldest first, so the first one in + * the list is the oldest. + */ +static void unplug_oldest_pwq(struct workqueue_struct *wq) +{ + struct pool_workqueue *pwq; + + lockdep_assert_held(&wq->mutex); + + /* Caller should make sure that pwqs isn't empty before calling */ + pwq = list_first_entry_or_null(&wq->pwqs, struct pool_workqueue, + pwqs_node); + raw_spin_lock_irq(&pwq->pool->lock); + if (pwq->plugged) { + pwq->plugged = false; + if (pwq_activate_first_inactive(pwq, true)) + kick_pool(pwq->pool); + } + raw_spin_unlock_irq(&pwq->pool->lock); +} + +/** + * node_activate_pending_pwq - Activate a pending pwq on a wq_node_nr_active + * @nna: wq_node_nr_active to activate a pending pwq for + * @caller_pool: worker_pool the caller is locking + * + * Activate a pwq in @nna->pending_pwqs. Called with @caller_pool locked. + * @caller_pool may be unlocked and relocked to lock other worker_pools. + */ +static void node_activate_pending_pwq(struct wq_node_nr_active *nna, + struct worker_pool *caller_pool) +{ + struct worker_pool *locked_pool = caller_pool; + struct pool_workqueue *pwq; + struct work_struct *work; + + lockdep_assert_held(&caller_pool->lock); + + raw_spin_lock(&nna->lock); +retry: + pwq = list_first_entry_or_null(&nna->pending_pwqs, + struct pool_workqueue, pending_node); + if (!pwq) + goto out_unlock; + + /* + * If @pwq is for a different pool than @locked_pool, we need to lock + * @pwq->pool->lock. Let's trylock first. If unsuccessful, do the unlock + * / lock dance. For that, we also need to release @nna->lock as it's + * nested inside pool locks. + */ + if (pwq->pool != locked_pool) { + raw_spin_unlock(&locked_pool->lock); + locked_pool = pwq->pool; + if (!raw_spin_trylock(&locked_pool->lock)) { + raw_spin_unlock(&nna->lock); + raw_spin_lock(&locked_pool->lock); + raw_spin_lock(&nna->lock); + goto retry; + } + } + + /* + * $pwq may not have any inactive work items due to e.g. cancellations. + * Drop it from pending_pwqs and see if there's another one. + */ + work = list_first_entry_or_null(&pwq->inactive_works, + struct work_struct, entry); + if (!work) { + list_del_init(&pwq->pending_node); + goto retry; + } + + /* + * Acquire an nr_active count and activate the inactive work item. If + * $pwq still has inactive work items, rotate it to the end of the + * pending_pwqs so that we round-robin through them. This means that + * inactive work items are not activated in queueing order which is fine + * given that there has never been any ordering across different pwqs. + */ + if (likely(tryinc_node_nr_active(nna))) { + pwq->nr_active++; + __pwq_activate_work(pwq, work); + + if (list_empty(&pwq->inactive_works)) + list_del_init(&pwq->pending_node); + else + list_move_tail(&pwq->pending_node, &nna->pending_pwqs); + + /* if activating a foreign pool, make sure it's running */ + if (pwq->pool != caller_pool) + kick_pool(pwq->pool); + } + +out_unlock: + raw_spin_unlock(&nna->lock); + if (locked_pool != caller_pool) { + raw_spin_unlock(&locked_pool->lock); + raw_spin_lock(&caller_pool->lock); + } } -static void pwq_activate_first_delayed(struct pool_workqueue *pwq) +/** + * pwq_dec_nr_active - Retire an active count + * @pwq: pool_workqueue of interest + * + * Decrement @pwq's nr_active and try to activate the first inactive work item. + * For unbound workqueues, this function may temporarily drop @pwq->pool->lock. + */ +static void pwq_dec_nr_active(struct pool_workqueue *pwq) { - struct work_struct *work = list_first_entry(&pwq->delayed_works, - struct work_struct, entry); + struct worker_pool *pool = pwq->pool; + struct wq_node_nr_active *nna = wq_node_nr_active(pwq->wq, pool->node); + + lockdep_assert_held(&pool->lock); + + /* + * @pwq->nr_active should be decremented for both percpu and unbound + * workqueues. + */ + pwq->nr_active--; + + /* + * For a percpu workqueue, it's simple. Just need to kick the first + * inactive work item on @pwq itself. + */ + if (!nna) { + pwq_activate_first_inactive(pwq, false); + return; + } + + /* + * If @pwq is for an unbound workqueue, it's more complicated because + * multiple pwqs and pools may be sharing the nr_active count. When a + * pwq needs to wait for an nr_active count, it puts itself on + * $nna->pending_pwqs. The following atomic_dec_return()'s implied + * memory barrier is paired with smp_mb() in pwq_tryinc_nr_active() to + * guarantee that either we see non-empty pending_pwqs or they see + * decremented $nna->nr. + * + * $nna->max may change as CPUs come online/offline and @pwq->wq's + * max_active gets updated. However, it is guaranteed to be equal to or + * larger than @pwq->wq->min_active which is above zero unless freezing. + * This maintains the forward progress guarantee. + */ + if (atomic_dec_return(&nna->nr) >= READ_ONCE(nna->max)) + return; - pwq_activate_delayed_work(work); + if (!list_empty(&nna->pending_pwqs)) + node_activate_pending_pwq(nna, pool); } /** * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight * @pwq: pwq of interest - * @color: color of work which left the queue + * @work_data: work_data of work which left the queue * * A work either has completed or is removed from pending queue, * decrement nr_in_flight of its pwq and handle workqueue flushing. * + * NOTE: + * For unbound workqueues, this function may temporarily drop @pwq->pool->lock + * and thus should be called after all other state updates for the in-flight + * work item is complete. + * * CONTEXT: - * spin_lock_irq(pool->lock). + * raw_spin_lock_irq(pool->lock). */ -static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color) +static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, unsigned long work_data) { - /* uncolored work items don't participate in flushing or nr_active */ - if (color == WORK_NO_COLOR) - goto out_put; + int color = get_work_color(work_data); - pwq->nr_in_flight[color]--; + if (!(work_data & WORK_STRUCT_INACTIVE)) + pwq_dec_nr_active(pwq); - pwq->nr_active--; - if (!list_empty(&pwq->delayed_works)) { - /* one down, submit a delayed one */ - if (pwq->nr_active < pwq->max_active) - pwq_activate_first_delayed(pwq); - } + pwq->nr_in_flight[color]--; /* is flush in progress and are we at the flushing tip? */ if (likely(pwq->flush_color != color)) @@ -1150,46 +2016,49 @@ out_put: /** * try_to_grab_pending - steal work item from worklist and disable irq * @work: work item to steal - * @is_dwork: @work is a delayed_work - * @flags: place to store irq state + * @cflags: %WORK_CANCEL_ flags + * @irq_flags: place to store irq state * * Try to grab PENDING bit of @work. This function can handle @work in any - * stable state - idle, on timer or on worklist. Return values are + * stable state - idle, on timer or on worklist. + * + * Return: * + * ======== ================================================================ * 1 if @work was pending and we successfully stole PENDING * 0 if @work was idle and we claimed PENDING * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry - * -ENOENT if someone else is canceling @work, this state may persist - * for arbitrarily long + * ======== ================================================================ * + * Note: * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting * interrupted while holding PENDING and @work off queue, irq must be * disabled on entry. This, combined with delayed_work->timer being * irqsafe, ensures that we return -EAGAIN for finite short period of time. * * On successful return, >= 0, irq is disabled and the caller is - * responsible for releasing it using local_irq_restore(*@flags). + * responsible for releasing it using local_irq_restore(*@irq_flags). * * This function is safe to call from any context including IRQ handler. */ -static int try_to_grab_pending(struct work_struct *work, bool is_dwork, - unsigned long *flags) +static int try_to_grab_pending(struct work_struct *work, u32 cflags, + unsigned long *irq_flags) { struct worker_pool *pool; struct pool_workqueue *pwq; - local_irq_save(*flags); + local_irq_save(*irq_flags); /* try to steal the timer if it exists */ - if (is_dwork) { + if (cflags & WORK_CANCEL_DELAYED) { struct delayed_work *dwork = to_delayed_work(work); /* - * dwork->timer is irqsafe. If del_timer() fails, it's + * dwork->timer is irqsafe. If timer_delete() fails, it's * guaranteed that the timer is not queued anywhere and not * running on the local CPU. */ - if (likely(del_timer(&dwork->timer))) + if (likely(timer_delete(&dwork->timer))) return 1; } @@ -1197,6 +2066,7 @@ static int try_to_grab_pending(struct work_struct *work, bool is_dwork, if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) return 0; + rcu_read_lock(); /* * The queueing is in progress, or it is already queued. Try to * steal it from ->worklist without clearing WORK_STRUCT_PENDING. @@ -1205,7 +2075,7 @@ static int try_to_grab_pending(struct work_struct *work, bool is_dwork, if (!pool) goto fail; - spin_lock(&pool->lock); + raw_spin_lock(&pool->lock); /* * work->data is guaranteed to point to pwq only while the work * item is queued on pwq->wq, and both updating work->data to point @@ -1216,37 +2086,79 @@ static int try_to_grab_pending(struct work_struct *work, bool is_dwork, */ pwq = get_work_pwq(work); if (pwq && pwq->pool == pool) { + unsigned long work_data = *work_data_bits(work); + debug_work_deactivate(work); /* - * A delayed work item cannot be grabbed directly because - * it might have linked NO_COLOR work items which, if left - * on the delayed_list, will confuse pwq->nr_active - * management later on and cause stall. Make sure the work - * item is activated before grabbing. + * A cancelable inactive work item must be in the + * pwq->inactive_works since a queued barrier can't be + * canceled (see the comments in insert_wq_barrier()). + * + * An inactive work item cannot be deleted directly because + * it might have linked barrier work items which, if left + * on the inactive_works list, will confuse pwq->nr_active + * management later on and cause stall. Move the linked + * barrier work items to the worklist when deleting the grabbed + * item. Also keep WORK_STRUCT_INACTIVE in work_data, so that + * it doesn't participate in nr_active management in later + * pwq_dec_nr_in_flight(). */ - if (*work_data_bits(work) & WORK_STRUCT_DELAYED) - pwq_activate_delayed_work(work); + if (work_data & WORK_STRUCT_INACTIVE) + move_linked_works(work, &pwq->pool->worklist, NULL); list_del_init(&work->entry); - pwq_dec_nr_in_flight(get_work_pwq(work), get_work_color(work)); - /* work->data points to pwq iff queued, point to pool */ - set_work_pool_and_keep_pending(work, pool->id); + /* + * work->data points to pwq iff queued. Let's point to pool. As + * this destroys work->data needed by the next step, stash it. + */ + set_work_pool_and_keep_pending(work, pool->id, + pool_offq_flags(pool)); + + /* must be the last step, see the function comment */ + pwq_dec_nr_in_flight(pwq, work_data); - spin_unlock(&pool->lock); + raw_spin_unlock(&pool->lock); + rcu_read_unlock(); return 1; } - spin_unlock(&pool->lock); + raw_spin_unlock(&pool->lock); fail: - local_irq_restore(*flags); - if (work_is_canceling(work)) - return -ENOENT; - cpu_relax(); + rcu_read_unlock(); + local_irq_restore(*irq_flags); return -EAGAIN; } /** + * work_grab_pending - steal work item from worklist and disable irq + * @work: work item to steal + * @cflags: %WORK_CANCEL_ flags + * @irq_flags: place to store IRQ state + * + * Grab PENDING bit of @work. @work can be in any stable state - idle, on timer + * or on worklist. + * + * Can be called from any context. IRQ is disabled on return with IRQ state + * stored in *@irq_flags. The caller is responsible for re-enabling it using + * local_irq_restore(). + * + * Returns %true if @work was pending. %false if idle. + */ +static bool work_grab_pending(struct work_struct *work, u32 cflags, + unsigned long *irq_flags) +{ + int ret; + + while (true) { + ret = try_to_grab_pending(work, cflags, irq_flags); + if (ret >= 0) + return ret; + cpu_relax(); + } +} + +/** * insert_work - insert a work into a pool * @pwq: pwq @work belongs to * @work: work to insert @@ -1257,27 +2169,20 @@ fail: * work_struct flags. * * CONTEXT: - * spin_lock_irq(pool->lock). + * raw_spin_lock_irq(pool->lock). */ static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, struct list_head *head, unsigned int extra_flags) { - struct worker_pool *pool = pwq->pool; + debug_work_activate(work); + + /* record the work call stack in order to print it in KASAN reports */ + kasan_record_aux_stack(work); /* we own @work, set data and link */ set_work_pwq(work, pwq, extra_flags); list_add_tail(&work->entry, head); get_pwq(pwq); - - /* - * Ensure either wq_worker_sleeping() sees the above - * list_add_tail() or we see zero nr_running to avoid workers lying - * around lazily while there are works to be processed. - */ - smp_mb(); - - if (__need_more_worker(pool)) - wake_up_worker(pool); } /* @@ -1290,18 +2195,42 @@ static bool is_chained_work(struct workqueue_struct *wq) worker = current_wq_worker(); /* - * Return %true iff I'm a worker execuing a work item on @wq. If + * Return %true iff I'm a worker executing a work item on @wq. If * I'm @worker, it's safe to dereference it without locking. */ return worker && worker->current_pwq->wq == wq; } +/* + * When queueing an unbound work item to a wq, prefer local CPU if allowed + * by wq_unbound_cpumask. Otherwise, round robin among the allowed ones to + * avoid perturbing sensitive tasks. + */ +static int wq_select_unbound_cpu(int cpu) +{ + int new_cpu; + + if (likely(!wq_debug_force_rr_cpu)) { + if (cpumask_test_cpu(cpu, wq_unbound_cpumask)) + return cpu; + } else { + pr_warn_once("workqueue: round-robin CPU selection forced, expect performance impact\n"); + } + + new_cpu = __this_cpu_read(wq_rr_cpu_last); + new_cpu = cpumask_next_and_wrap(new_cpu, wq_unbound_cpumask, cpu_online_mask); + if (unlikely(new_cpu >= nr_cpu_ids)) + return cpu; + __this_cpu_write(wq_rr_cpu_last, new_cpu); + + return new_cpu; +} + static void __queue_work(int cpu, struct workqueue_struct *wq, struct work_struct *work) { struct pool_workqueue *pwq; - struct worker_pool *last_pool; - struct list_head *worklist; + struct worker_pool *last_pool, *pool; unsigned int work_flags; unsigned int req_cpu = cpu; @@ -1311,59 +2240,71 @@ static void __queue_work(int cpu, struct workqueue_struct *wq, * queued or lose PENDING. Grabbing PENDING and queueing should * happen with IRQ disabled. */ - WARN_ON_ONCE(!irqs_disabled()); + lockdep_assert_irqs_disabled(); - debug_work_activate(work); - - /* if dying, only works from the same workqueue are allowed */ - if (unlikely(wq->flags & __WQ_DRAINING) && - WARN_ON_ONCE(!is_chained_work(wq))) + /* + * For a draining wq, only works from the same workqueue are + * allowed. The __WQ_DESTROYING helps to spot the issue that + * queues a new work item to a wq after destroy_workqueue(wq). + */ + if (unlikely(wq->flags & (__WQ_DESTROYING | __WQ_DRAINING) && + WARN_ONCE(!is_chained_work(wq), "workqueue: cannot queue %ps on wq %s\n", + work->func, wq->name))) { return; + } + rcu_read_lock(); retry: - if (req_cpu == WORK_CPU_UNBOUND) - cpu = raw_smp_processor_id(); - /* pwq which will be used unless @work is executing elsewhere */ - if (!(wq->flags & WQ_UNBOUND)) - pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); - else - pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); + if (req_cpu == WORK_CPU_UNBOUND) { + if (wq->flags & WQ_UNBOUND) + cpu = wq_select_unbound_cpu(raw_smp_processor_id()); + else + cpu = raw_smp_processor_id(); + } + + pwq = rcu_dereference(*per_cpu_ptr(wq->cpu_pwq, cpu)); + pool = pwq->pool; /* * If @work was previously on a different pool, it might still be * running there, in which case the work needs to be queued on that * pool to guarantee non-reentrancy. + * + * For ordered workqueue, work items must be queued on the newest pwq + * for accurate order management. Guaranteed order also guarantees + * non-reentrancy. See the comments above unplug_oldest_pwq(). */ last_pool = get_work_pool(work); - if (last_pool && last_pool != pwq->pool) { + if (last_pool && last_pool != pool && !(wq->flags & __WQ_ORDERED)) { struct worker *worker; - spin_lock(&last_pool->lock); + raw_spin_lock(&last_pool->lock); worker = find_worker_executing_work(last_pool, work); if (worker && worker->current_pwq->wq == wq) { pwq = worker->current_pwq; + pool = pwq->pool; + WARN_ON_ONCE(pool != last_pool); } else { /* meh... not running there, queue here */ - spin_unlock(&last_pool->lock); - spin_lock(&pwq->pool->lock); + raw_spin_unlock(&last_pool->lock); + raw_spin_lock(&pool->lock); } } else { - spin_lock(&pwq->pool->lock); + raw_spin_lock(&pool->lock); } /* - * pwq is determined and locked. For unbound pools, we could have - * raced with pwq release and it could already be dead. If its - * refcnt is zero, repeat pwq selection. Note that pwqs never die - * without another pwq replacing it in the numa_pwq_tbl or while - * work items are executing on it, so the retrying is guaranteed to - * make forward-progress. + * pwq is determined and locked. For unbound pools, we could have raced + * with pwq release and it could already be dead. If its refcnt is zero, + * repeat pwq selection. Note that unbound pwqs never die without + * another pwq replacing it in cpu_pwq or while work items are executing + * on it, so the retrying is guaranteed to make forward-progress. */ if (unlikely(!pwq->refcnt)) { if (wq->flags & WQ_UNBOUND) { - spin_unlock(&pwq->pool->lock); + raw_spin_unlock(&pool->lock); cpu_relax(); goto retry; } @@ -1375,26 +2316,47 @@ retry: /* pwq determined, queue */ trace_workqueue_queue_work(req_cpu, pwq, work); - if (WARN_ON(!list_empty(&work->entry))) { - spin_unlock(&pwq->pool->lock); - return; - } + if (WARN_ON(!list_empty(&work->entry))) + goto out; pwq->nr_in_flight[pwq->work_color]++; work_flags = work_color_to_flags(pwq->work_color); - if (likely(pwq->nr_active < pwq->max_active)) { + /* + * Limit the number of concurrently active work items to max_active. + * @work must also queue behind existing inactive work items to maintain + * ordering when max_active changes. See wq_adjust_max_active(). + */ + if (list_empty(&pwq->inactive_works) && pwq_tryinc_nr_active(pwq, false)) { + if (list_empty(&pool->worklist)) + pool->watchdog_ts = jiffies; + trace_workqueue_activate_work(work); - pwq->nr_active++; - worklist = &pwq->pool->worklist; + insert_work(pwq, work, &pool->worklist, work_flags); + kick_pool(pool); } else { - work_flags |= WORK_STRUCT_DELAYED; - worklist = &pwq->delayed_works; + work_flags |= WORK_STRUCT_INACTIVE; + insert_work(pwq, work, &pwq->inactive_works, work_flags); } - insert_work(pwq, work, worklist, work_flags); +out: + raw_spin_unlock(&pool->lock); + rcu_read_unlock(); +} + +static bool clear_pending_if_disabled(struct work_struct *work) +{ + unsigned long data = *work_data_bits(work); + struct work_offq_data offqd; + + if (likely((data & WORK_STRUCT_PWQ) || + !(data & WORK_OFFQ_DISABLE_MASK))) + return false; - spin_unlock(&pwq->pool->lock); + work_offqd_unpack(&offqd, data); + set_work_pool_and_clear_pending(work, offqd.pool_id, + work_offqd_pack_flags(&offqd)); + return true; } /** @@ -1403,32 +2365,117 @@ retry: * @wq: workqueue to use * @work: work to queue * - * Returns %false if @work was already on a queue, %true otherwise. - * * We queue the work to a specific CPU, the caller must ensure it - * can't go away. + * can't go away. Callers that fail to ensure that the specified + * CPU cannot go away will execute on a randomly chosen CPU. + * But note well that callers specifying a CPU that never has been + * online will get a splat. + * + * Return: %false if @work was already on a queue, %true otherwise. */ bool queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) { bool ret = false; - unsigned long flags; + unsigned long irq_flags; - local_irq_save(flags); + local_irq_save(irq_flags); - if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { + if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)) && + !clear_pending_if_disabled(work)) { __queue_work(cpu, wq, work); ret = true; } - local_irq_restore(flags); + local_irq_restore(irq_flags); return ret; } EXPORT_SYMBOL(queue_work_on); -void delayed_work_timer_fn(unsigned long __data) +/** + * select_numa_node_cpu - Select a CPU based on NUMA node + * @node: NUMA node ID that we want to select a CPU from + * + * This function will attempt to find a "random" cpu available on a given + * node. If there are no CPUs available on the given node it will return + * WORK_CPU_UNBOUND indicating that we should just schedule to any + * available CPU if we need to schedule this work. + */ +static int select_numa_node_cpu(int node) +{ + int cpu; + + /* Delay binding to CPU if node is not valid or online */ + if (node < 0 || node >= MAX_NUMNODES || !node_online(node)) + return WORK_CPU_UNBOUND; + + /* Use local node/cpu if we are already there */ + cpu = raw_smp_processor_id(); + if (node == cpu_to_node(cpu)) + return cpu; + + /* Use "random" otherwise know as "first" online CPU of node */ + cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask); + + /* If CPU is valid return that, otherwise just defer */ + return cpu < nr_cpu_ids ? cpu : WORK_CPU_UNBOUND; +} + +/** + * queue_work_node - queue work on a "random" cpu for a given NUMA node + * @node: NUMA node that we are targeting the work for + * @wq: workqueue to use + * @work: work to queue + * + * We queue the work to a "random" CPU within a given NUMA node. The basic + * idea here is to provide a way to somehow associate work with a given + * NUMA node. + * + * This function will only make a best effort attempt at getting this onto + * the right NUMA node. If no node is requested or the requested node is + * offline then we just fall back to standard queue_work behavior. + * + * Currently the "random" CPU ends up being the first available CPU in the + * intersection of cpu_online_mask and the cpumask of the node, unless we + * are running on the node. In that case we just use the current CPU. + * + * Return: %false if @work was already on a queue, %true otherwise. + */ +bool queue_work_node(int node, struct workqueue_struct *wq, + struct work_struct *work) +{ + unsigned long irq_flags; + bool ret = false; + + /* + * This current implementation is specific to unbound workqueues. + * Specifically we only return the first available CPU for a given + * node instead of cycling through individual CPUs within the node. + * + * If this is used with a per-cpu workqueue then the logic in + * workqueue_select_cpu_near would need to be updated to allow for + * some round robin type logic. + */ + WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)); + + local_irq_save(irq_flags); + + if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)) && + !clear_pending_if_disabled(work)) { + int cpu = select_numa_node_cpu(node); + + __queue_work(cpu, wq, work); + ret = true; + } + + local_irq_restore(irq_flags); + return ret; +} +EXPORT_SYMBOL_GPL(queue_work_node); + +void delayed_work_timer_fn(struct timer_list *t) { - struct delayed_work *dwork = (struct delayed_work *)__data; + struct delayed_work *dwork = timer_container_of(dwork, t, timer); /* should have been called from irqsafe timer with irq already off */ __queue_work(dwork->cpu, dwork->wq, &dwork->work); @@ -1441,8 +2488,8 @@ static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, struct timer_list *timer = &dwork->timer; struct work_struct *work = &dwork->work; - WARN_ON_ONCE(timer->function != delayed_work_timer_fn || - timer->data != (unsigned long)dwork); + WARN_ON_ONCE(!wq); + WARN_ON_ONCE(timer->function != delayed_work_timer_fn); WARN_ON_ONCE(timer_pending(timer)); WARN_ON_ONCE(!list_empty(&work->entry)); @@ -1457,16 +2504,23 @@ static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, return; } - timer_stats_timer_set_start_info(&dwork->timer); - + WARN_ON_ONCE(cpu != WORK_CPU_UNBOUND && !cpu_online(cpu)); dwork->wq = wq; dwork->cpu = cpu; timer->expires = jiffies + delay; - if (unlikely(cpu != WORK_CPU_UNBOUND)) + if (housekeeping_enabled(HK_TYPE_TIMER)) { + /* If the current cpu is a housekeeping cpu, use it. */ + cpu = smp_processor_id(); + if (!housekeeping_test_cpu(cpu, HK_TYPE_TIMER)) + cpu = housekeeping_any_cpu(HK_TYPE_TIMER); add_timer_on(timer, cpu); - else - add_timer(timer); + } else { + if (likely(cpu == WORK_CPU_UNBOUND)) + add_timer_global(timer); + else + add_timer_on(timer, cpu); + } } /** @@ -1476,7 +2530,13 @@ static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, * @dwork: work to queue * @delay: number of jiffies to wait before queueing * - * Returns %false if @work was already on a queue, %true otherwise. If + * We queue the delayed_work to a specific CPU, for non-zero delays the + * caller must ensure it is online and can't go away. Callers that fail + * to ensure this, may get @dwork->timer queued to an offlined CPU and + * this will prevent queueing of @dwork->work unless the offlined CPU + * becomes online again. + * + * Return: %false if @work was already on a queue, %true otherwise. If * @delay is zero and @dwork is idle, it will be scheduled for immediate * execution. */ @@ -1485,17 +2545,18 @@ bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, { struct work_struct *work = &dwork->work; bool ret = false; - unsigned long flags; + unsigned long irq_flags; /* read the comment in __queue_work() */ - local_irq_save(flags); + local_irq_save(irq_flags); - if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { + if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)) && + !clear_pending_if_disabled(work)) { __queue_delayed_work(cpu, wq, dwork, delay); ret = true; } - local_irq_restore(flags); + local_irq_restore(irq_flags); return ret; } EXPORT_SYMBOL(queue_delayed_work_on); @@ -1512,7 +2573,7 @@ EXPORT_SYMBOL(queue_delayed_work_on); * zero, @work is guaranteed to be scheduled immediately regardless of its * current state. * - * Returns %false if @dwork was idle and queued, %true if @dwork was + * Return: %false if @dwork was idle and queued, %true if @dwork was * pending and its timer was modified. * * This function is safe to call from any context including IRQ handler. @@ -1521,355 +2582,398 @@ EXPORT_SYMBOL(queue_delayed_work_on); bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, struct delayed_work *dwork, unsigned long delay) { - unsigned long flags; - int ret; + unsigned long irq_flags; + bool ret; - do { - ret = try_to_grab_pending(&dwork->work, true, &flags); - } while (unlikely(ret == -EAGAIN)); + ret = work_grab_pending(&dwork->work, WORK_CANCEL_DELAYED, &irq_flags); - if (likely(ret >= 0)) { + if (!clear_pending_if_disabled(&dwork->work)) __queue_delayed_work(cpu, wq, dwork, delay); - local_irq_restore(flags); - } - /* -ENOENT from try_to_grab_pending() becomes %true */ + local_irq_restore(irq_flags); return ret; } EXPORT_SYMBOL_GPL(mod_delayed_work_on); +static void rcu_work_rcufn(struct rcu_head *rcu) +{ + struct rcu_work *rwork = container_of(rcu, struct rcu_work, rcu); + + /* read the comment in __queue_work() */ + local_irq_disable(); + __queue_work(WORK_CPU_UNBOUND, rwork->wq, &rwork->work); + local_irq_enable(); +} + /** - * worker_enter_idle - enter idle state - * @worker: worker which is entering idle state - * - * @worker is entering idle state. Update stats and idle timer if - * necessary. + * queue_rcu_work - queue work after a RCU grace period + * @wq: workqueue to use + * @rwork: work to queue * - * LOCKING: - * spin_lock_irq(pool->lock). + * Return: %false if @rwork was already pending, %true otherwise. Note + * that a full RCU grace period is guaranteed only after a %true return. + * While @rwork is guaranteed to be executed after a %false return, the + * execution may happen before a full RCU grace period has passed. */ -static void worker_enter_idle(struct worker *worker) +bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork) { - struct worker_pool *pool = worker->pool; + struct work_struct *work = &rwork->work; - if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || - WARN_ON_ONCE(!list_empty(&worker->entry) && - (worker->hentry.next || worker->hentry.pprev))) - return; + /* + * rcu_work can't be canceled or disabled. Warn if the user reached + * inside @rwork and disabled the inner work. + */ + if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)) && + !WARN_ON_ONCE(clear_pending_if_disabled(work))) { + rwork->wq = wq; + call_rcu_hurry(&rwork->rcu, rcu_work_rcufn); + return true; + } - /* can't use worker_set_flags(), also called from start_worker() */ - worker->flags |= WORKER_IDLE; - pool->nr_idle++; - worker->last_active = jiffies; + return false; +} +EXPORT_SYMBOL(queue_rcu_work); - /* idle_list is LIFO */ - list_add(&worker->entry, &pool->idle_list); +static struct worker *alloc_worker(int node) +{ + struct worker *worker; - if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) - mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); + worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, node); + if (worker) { + INIT_LIST_HEAD(&worker->entry); + INIT_LIST_HEAD(&worker->scheduled); + INIT_LIST_HEAD(&worker->node); + /* on creation a worker is in !idle && prep state */ + worker->flags = WORKER_PREP; + } + return worker; +} - /* - * Sanity check nr_running. Because wq_unbind_fn() releases - * pool->lock between setting %WORKER_UNBOUND and zapping - * nr_running, the warning may trigger spuriously. Check iff - * unbind is not in progress. - */ - WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && - pool->nr_workers == pool->nr_idle && - atomic_read(&pool->nr_running)); +static cpumask_t *pool_allowed_cpus(struct worker_pool *pool) +{ + if (pool->cpu < 0 && pool->attrs->affn_strict) + return pool->attrs->__pod_cpumask; + else + return pool->attrs->cpumask; } /** - * worker_leave_idle - leave idle state - * @worker: worker which is leaving idle state - * - * @worker is leaving idle state. Update stats. + * worker_attach_to_pool() - attach a worker to a pool + * @worker: worker to be attached + * @pool: the target pool * - * LOCKING: - * spin_lock_irq(pool->lock). + * Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and + * cpu-binding of @worker are kept coordinated with the pool across + * cpu-[un]hotplugs. */ -static void worker_leave_idle(struct worker *worker) +static void worker_attach_to_pool(struct worker *worker, + struct worker_pool *pool) { - struct worker_pool *pool = worker->pool; + mutex_lock(&wq_pool_attach_mutex); - if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) - return; - worker_clr_flags(worker, WORKER_IDLE); - pool->nr_idle--; - list_del_init(&worker->entry); + /* + * The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains stable + * across this function. See the comments above the flag definition for + * details. BH workers are, while per-CPU, always DISASSOCIATED. + */ + if (pool->flags & POOL_DISASSOCIATED) { + worker->flags |= WORKER_UNBOUND; + } else { + WARN_ON_ONCE(pool->flags & POOL_BH); + kthread_set_per_cpu(worker->task, pool->cpu); + } + + if (worker->rescue_wq) + set_cpus_allowed_ptr(worker->task, pool_allowed_cpus(pool)); + + list_add_tail(&worker->node, &pool->workers); + worker->pool = pool; + + mutex_unlock(&wq_pool_attach_mutex); +} + +static void unbind_worker(struct worker *worker) +{ + lockdep_assert_held(&wq_pool_attach_mutex); + + kthread_set_per_cpu(worker->task, -1); + if (cpumask_intersects(wq_unbound_cpumask, cpu_active_mask)) + WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, wq_unbound_cpumask) < 0); + else + WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0); +} + + +static void detach_worker(struct worker *worker) +{ + lockdep_assert_held(&wq_pool_attach_mutex); + + unbind_worker(worker); + list_del(&worker->node); } /** - * worker_maybe_bind_and_lock - try to bind %current to worker_pool and lock it - * @pool: target worker_pool - * - * Bind %current to the cpu of @pool if it is associated and lock @pool. - * - * Works which are scheduled while the cpu is online must at least be - * scheduled to a worker which is bound to the cpu so that if they are - * flushed from cpu callbacks while cpu is going down, they are - * guaranteed to execute on the cpu. - * - * This function is to be used by unbound workers and rescuers to bind - * themselves to the target cpu and may race with cpu going down or - * coming online. kthread_bind() can't be used because it may put the - * worker to already dead cpu and set_cpus_allowed_ptr() can't be used - * verbatim as it's best effort and blocking and pool may be - * [dis]associated in the meantime. - * - * This function tries set_cpus_allowed() and locks pool and verifies the - * binding against %POOL_DISASSOCIATED which is set during - * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker - * enters idle state or fetches works without dropping lock, it can - * guarantee the scheduling requirement described in the first paragraph. + * worker_detach_from_pool() - detach a worker from its pool + * @worker: worker which is attached to its pool * - * CONTEXT: - * Might sleep. Called without any lock but returns with pool->lock - * held. - * - * RETURNS: - * %true if the associated pool is online (@worker is successfully - * bound), %false if offline. + * Undo the attaching which had been done in worker_attach_to_pool(). The + * caller worker shouldn't access to the pool after detached except it has + * other reference to the pool. */ -static bool worker_maybe_bind_and_lock(struct worker_pool *pool) -__acquires(&pool->lock) +static void worker_detach_from_pool(struct worker *worker) { - while (true) { - /* - * The following call may fail, succeed or succeed - * without actually migrating the task to the cpu if - * it races with cpu hotunplug operation. Verify - * against POOL_DISASSOCIATED. - */ - if (!(pool->flags & POOL_DISASSOCIATED)) - set_cpus_allowed_ptr(current, pool->attrs->cpumask); + struct worker_pool *pool = worker->pool; - spin_lock_irq(&pool->lock); - if (pool->flags & POOL_DISASSOCIATED) - return false; - if (task_cpu(current) == pool->cpu && - cpumask_equal(¤t->cpus_allowed, pool->attrs->cpumask)) - return true; - spin_unlock_irq(&pool->lock); + /* there is one permanent BH worker per CPU which should never detach */ + WARN_ON_ONCE(pool->flags & POOL_BH); - /* - * We've raced with CPU hot[un]plug. Give it a breather - * and retry migration. cond_resched() is required here; - * otherwise, we might deadlock against cpu_stop trying to - * bring down the CPU on non-preemptive kernel. - */ - cpu_relax(); - cond_resched(); - } + mutex_lock(&wq_pool_attach_mutex); + detach_worker(worker); + worker->pool = NULL; + mutex_unlock(&wq_pool_attach_mutex); + + /* clear leftover flags without pool->lock after it is detached */ + worker->flags &= ~(WORKER_UNBOUND | WORKER_REBOUND); } -static struct worker *alloc_worker(void) +static int format_worker_id(char *buf, size_t size, struct worker *worker, + struct worker_pool *pool) { - struct worker *worker; + if (worker->rescue_wq) + return scnprintf(buf, size, "kworker/R-%s", + worker->rescue_wq->name); - worker = kzalloc(sizeof(*worker), GFP_KERNEL); - if (worker) { - INIT_LIST_HEAD(&worker->entry); - INIT_LIST_HEAD(&worker->scheduled); - /* on creation a worker is in !idle && prep state */ - worker->flags = WORKER_PREP; + if (pool) { + if (pool->cpu >= 0) + return scnprintf(buf, size, "kworker/%d:%d%s", + pool->cpu, worker->id, + pool->attrs->nice < 0 ? "H" : ""); + else + return scnprintf(buf, size, "kworker/u%d:%d", + pool->id, worker->id); + } else { + return scnprintf(buf, size, "kworker/dying"); } - return worker; } /** * create_worker - create a new workqueue worker * @pool: pool the new worker will belong to * - * Create a new worker which is bound to @pool. The returned worker - * can be started by calling start_worker() or destroyed using - * destroy_worker(). + * Create and start a new worker which is attached to @pool. * * CONTEXT: * Might sleep. Does GFP_KERNEL allocations. * - * RETURNS: + * Return: * Pointer to the newly created worker. */ static struct worker *create_worker(struct worker_pool *pool) { - struct worker *worker = NULL; - int id = -1; - char id_buf[16]; - - lockdep_assert_held(&pool->manager_mutex); - - /* - * ID is needed to determine kthread name. Allocate ID first - * without installing the pointer. - */ - idr_preload(GFP_KERNEL); - spin_lock_irq(&pool->lock); - - id = idr_alloc(&pool->worker_idr, NULL, 0, 0, GFP_NOWAIT); + struct worker *worker; + int id; - spin_unlock_irq(&pool->lock); - idr_preload_end(); - if (id < 0) - goto fail; + /* ID is needed to determine kthread name */ + id = ida_alloc(&pool->worker_ida, GFP_KERNEL); + if (id < 0) { + pr_err_once("workqueue: Failed to allocate a worker ID: %pe\n", + ERR_PTR(id)); + return NULL; + } - worker = alloc_worker(); - if (!worker) + worker = alloc_worker(pool->node); + if (!worker) { + pr_err_once("workqueue: Failed to allocate a worker\n"); goto fail; + } - worker->pool = pool; worker->id = id; - if (pool->cpu >= 0) - snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id, - pool->attrs->nice < 0 ? "H" : ""); - else - snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id); + if (!(pool->flags & POOL_BH)) { + char id_buf[WORKER_ID_LEN]; + + format_worker_id(id_buf, sizeof(id_buf), worker, pool); + worker->task = kthread_create_on_node(worker_thread, worker, + pool->node, "%s", id_buf); + if (IS_ERR(worker->task)) { + if (PTR_ERR(worker->task) == -EINTR) { + pr_err("workqueue: Interrupted when creating a worker thread \"%s\"\n", + id_buf); + } else { + pr_err_once("workqueue: Failed to create a worker thread: %pe", + worker->task); + } + goto fail; + } - worker->task = kthread_create_on_node(worker_thread, worker, pool->node, - "kworker/%s", id_buf); - if (IS_ERR(worker->task)) - goto fail; + set_user_nice(worker->task, pool->attrs->nice); + kthread_bind_mask(worker->task, pool_allowed_cpus(pool)); + } - /* - * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any - * online CPUs. It'll be re-applied when any of the CPUs come up. - */ - set_user_nice(worker->task, pool->attrs->nice); - set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); + /* successful, attach the worker to the pool */ + worker_attach_to_pool(worker, pool); - /* prevent userland from meddling with cpumask of workqueue workers */ - worker->task->flags |= PF_NO_SETAFFINITY; + /* start the newly created worker */ + raw_spin_lock_irq(&pool->lock); + + worker->pool->nr_workers++; + worker_enter_idle(worker); /* - * The caller is responsible for ensuring %POOL_DISASSOCIATED - * remains stable across this function. See the comments above the - * flag definition for details. + * @worker is waiting on a completion in kthread() and will trigger hung + * check if not woken up soon. As kick_pool() is noop if @pool is empty, + * wake it up explicitly. */ - if (pool->flags & POOL_DISASSOCIATED) - worker->flags |= WORKER_UNBOUND; + if (worker->task) + wake_up_process(worker->task); - /* successful, commit the pointer to idr */ - spin_lock_irq(&pool->lock); - idr_replace(&pool->worker_idr, worker, worker->id); - spin_unlock_irq(&pool->lock); + raw_spin_unlock_irq(&pool->lock); return worker; fail: - if (id >= 0) { - spin_lock_irq(&pool->lock); - idr_remove(&pool->worker_idr, id); - spin_unlock_irq(&pool->lock); - } + ida_free(&pool->worker_ida, id); kfree(worker); return NULL; } -/** - * start_worker - start a newly created worker - * @worker: worker to start - * - * Make the pool aware of @worker and start it. - * - * CONTEXT: - * spin_lock_irq(pool->lock). - */ -static void start_worker(struct worker *worker) +static void detach_dying_workers(struct list_head *cull_list) { - worker->flags |= WORKER_STARTED; - worker->pool->nr_workers++; - worker_enter_idle(worker); - wake_up_process(worker->task); + struct worker *worker; + + list_for_each_entry(worker, cull_list, entry) + detach_worker(worker); } -/** - * create_and_start_worker - create and start a worker for a pool - * @pool: the target pool - * - * Grab the managership of @pool and create and start a new worker for it. - */ -static int create_and_start_worker(struct worker_pool *pool) +static void reap_dying_workers(struct list_head *cull_list) { - struct worker *worker; - - mutex_lock(&pool->manager_mutex); + struct worker *worker, *tmp; - worker = create_worker(pool); - if (worker) { - spin_lock_irq(&pool->lock); - start_worker(worker); - spin_unlock_irq(&pool->lock); + list_for_each_entry_safe(worker, tmp, cull_list, entry) { + list_del_init(&worker->entry); + kthread_stop_put(worker->task); + kfree(worker); } - - mutex_unlock(&pool->manager_mutex); - - return worker ? 0 : -ENOMEM; } /** - * destroy_worker - destroy a workqueue worker + * set_worker_dying - Tag a worker for destruction * @worker: worker to be destroyed + * @list: transfer worker away from its pool->idle_list and into list * - * Destroy @worker and adjust @pool stats accordingly. + * Tag @worker for destruction and adjust @pool stats accordingly. The worker + * should be idle. * * CONTEXT: - * spin_lock_irq(pool->lock) which is released and regrabbed. + * raw_spin_lock_irq(pool->lock). */ -static void destroy_worker(struct worker *worker) +static void set_worker_dying(struct worker *worker, struct list_head *list) { struct worker_pool *pool = worker->pool; - lockdep_assert_held(&pool->manager_mutex); lockdep_assert_held(&pool->lock); + lockdep_assert_held(&wq_pool_attach_mutex); /* sanity check frenzy */ if (WARN_ON(worker->current_work) || - WARN_ON(!list_empty(&worker->scheduled))) + WARN_ON(!list_empty(&worker->scheduled)) || + WARN_ON(!(worker->flags & WORKER_IDLE))) return; - if (worker->flags & WORKER_STARTED) - pool->nr_workers--; - if (worker->flags & WORKER_IDLE) - pool->nr_idle--; + pool->nr_workers--; + pool->nr_idle--; - list_del_init(&worker->entry); worker->flags |= WORKER_DIE; - idr_remove(&pool->worker_idr, worker->id); - - spin_unlock_irq(&pool->lock); + list_move(&worker->entry, list); - kthread_stop(worker->task); - kfree(worker); - - spin_lock_irq(&pool->lock); + /* get an extra task struct reference for later kthread_stop_put() */ + get_task_struct(worker->task); } -static void idle_worker_timeout(unsigned long __pool) +/** + * idle_worker_timeout - check if some idle workers can now be deleted. + * @t: The pool's idle_timer that just expired + * + * The timer is armed in worker_enter_idle(). Note that it isn't disarmed in + * worker_leave_idle(), as a worker flicking between idle and active while its + * pool is at the too_many_workers() tipping point would cause too much timer + * housekeeping overhead. Since IDLE_WORKER_TIMEOUT is long enough, we just let + * it expire and re-evaluate things from there. + */ +static void idle_worker_timeout(struct timer_list *t) { - struct worker_pool *pool = (void *)__pool; + struct worker_pool *pool = timer_container_of(pool, t, idle_timer); + bool do_cull = false; + + if (work_pending(&pool->idle_cull_work)) + return; - spin_lock_irq(&pool->lock); + raw_spin_lock_irq(&pool->lock); if (too_many_workers(pool)) { struct worker *worker; unsigned long expires; /* idle_list is kept in LIFO order, check the last one */ - worker = list_entry(pool->idle_list.prev, struct worker, entry); + worker = list_last_entry(&pool->idle_list, struct worker, entry); + expires = worker->last_active + IDLE_WORKER_TIMEOUT; + do_cull = !time_before(jiffies, expires); + + if (!do_cull) + mod_timer(&pool->idle_timer, expires); + } + raw_spin_unlock_irq(&pool->lock); + + if (do_cull) + queue_work(system_dfl_wq, &pool->idle_cull_work); +} + +/** + * idle_cull_fn - cull workers that have been idle for too long. + * @work: the pool's work for handling these idle workers + * + * This goes through a pool's idle workers and gets rid of those that have been + * idle for at least IDLE_WORKER_TIMEOUT seconds. + * + * We don't want to disturb isolated CPUs because of a pcpu kworker being + * culled, so this also resets worker affinity. This requires a sleepable + * context, hence the split between timer callback and work item. + */ +static void idle_cull_fn(struct work_struct *work) +{ + struct worker_pool *pool = container_of(work, struct worker_pool, idle_cull_work); + LIST_HEAD(cull_list); + + /* + * Grabbing wq_pool_attach_mutex here ensures an already-running worker + * cannot proceed beyong set_pf_worker() in its self-destruct path. + * This is required as a previously-preempted worker could run after + * set_worker_dying() has happened but before detach_dying_workers() did. + */ + mutex_lock(&wq_pool_attach_mutex); + raw_spin_lock_irq(&pool->lock); + + while (too_many_workers(pool)) { + struct worker *worker; + unsigned long expires; + + worker = list_last_entry(&pool->idle_list, struct worker, entry); expires = worker->last_active + IDLE_WORKER_TIMEOUT; - if (time_before(jiffies, expires)) + if (time_before(jiffies, expires)) { mod_timer(&pool->idle_timer, expires); - else { - /* it's been idle for too long, wake up manager */ - pool->flags |= POOL_MANAGE_WORKERS; - wake_up_worker(pool); + break; } + + set_worker_dying(worker, &cull_list); } - spin_unlock_irq(&pool->lock); + raw_spin_unlock_irq(&pool->lock); + detach_dying_workers(&cull_list); + mutex_unlock(&wq_pool_attach_mutex); + + reap_dying_workers(&cull_list); } static void send_mayday(struct work_struct *work) @@ -1884,18 +2988,25 @@ static void send_mayday(struct work_struct *work) /* mayday mayday mayday */ if (list_empty(&pwq->mayday_node)) { + /* + * If @pwq is for an unbound wq, its base ref may be put at + * any time due to an attribute change. Pin @pwq until the + * rescuer is done with it. + */ + get_pwq(pwq); list_add_tail(&pwq->mayday_node, &wq->maydays); wake_up_process(wq->rescuer->task); + pwq->stats[PWQ_STAT_MAYDAY]++; } } -static void pool_mayday_timeout(unsigned long __pool) +static void pool_mayday_timeout(struct timer_list *t) { - struct worker_pool *pool = (void *)__pool; + struct worker_pool *pool = timer_container_of(pool, t, mayday_timer); struct work_struct *work; - spin_lock_irq(&wq_mayday_lock); /* for wq->maydays */ - spin_lock(&pool->lock); + raw_spin_lock_irq(&pool->lock); + raw_spin_lock(&wq_mayday_lock); /* for wq->maydays */ if (need_to_create_worker(pool)) { /* @@ -1908,8 +3019,8 @@ static void pool_mayday_timeout(unsigned long __pool) send_mayday(work); } - spin_unlock(&pool->lock); - spin_unlock_irq(&wq_mayday_lock); + raw_spin_unlock(&wq_mayday_lock); + raw_spin_unlock_irq(&pool->lock); mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); } @@ -1928,93 +3039,65 @@ static void pool_mayday_timeout(unsigned long __pool) * may_start_working() %true. * * LOCKING: - * spin_lock_irq(pool->lock) which may be released and regrabbed + * raw_spin_lock_irq(pool->lock) which may be released and regrabbed * multiple times. Does GFP_KERNEL allocations. Called only from * manager. - * - * RETURNS: - * %false if no action was taken and pool->lock stayed locked, %true - * otherwise. */ -static bool maybe_create_worker(struct worker_pool *pool) +static void maybe_create_worker(struct worker_pool *pool) __releases(&pool->lock) __acquires(&pool->lock) { - if (!need_to_create_worker(pool)) - return false; restart: - spin_unlock_irq(&pool->lock); + raw_spin_unlock_irq(&pool->lock); /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); while (true) { - struct worker *worker; - - worker = create_worker(pool); - if (worker) { - del_timer_sync(&pool->mayday_timer); - spin_lock_irq(&pool->lock); - start_worker(worker); - if (WARN_ON_ONCE(need_to_create_worker(pool))) - goto restart; - return true; - } - - if (!need_to_create_worker(pool)) + if (create_worker(pool) || !need_to_create_worker(pool)) break; - __set_current_state(TASK_INTERRUPTIBLE); - schedule_timeout(CREATE_COOLDOWN); + schedule_timeout_interruptible(CREATE_COOLDOWN); if (!need_to_create_worker(pool)) break; } - del_timer_sync(&pool->mayday_timer); - spin_lock_irq(&pool->lock); + timer_delete_sync(&pool->mayday_timer); + raw_spin_lock_irq(&pool->lock); + /* + * This is necessary even after a new worker was just successfully + * created as @pool->lock was dropped and the new worker might have + * already become busy. + */ if (need_to_create_worker(pool)) goto restart; - return true; } -/** - * maybe_destroy_worker - destroy workers which have been idle for a while - * @pool: pool to destroy workers for - * - * Destroy @pool workers which have been idle for longer than - * IDLE_WORKER_TIMEOUT. - * - * LOCKING: - * spin_lock_irq(pool->lock) which may be released and regrabbed - * multiple times. Called only from manager. - * - * RETURNS: - * %false if no action was taken and pool->lock stayed locked, %true - * otherwise. - */ -static bool maybe_destroy_workers(struct worker_pool *pool) +#ifdef CONFIG_PREEMPT_RT +static void worker_lock_callback(struct worker_pool *pool) { - bool ret = false; + spin_lock(&pool->cb_lock); +} - while (too_many_workers(pool)) { - struct worker *worker; - unsigned long expires; +static void worker_unlock_callback(struct worker_pool *pool) +{ + spin_unlock(&pool->cb_lock); +} - worker = list_entry(pool->idle_list.prev, struct worker, entry); - expires = worker->last_active + IDLE_WORKER_TIMEOUT; +static void workqueue_callback_cancel_wait_running(struct worker_pool *pool) +{ + spin_lock(&pool->cb_lock); + spin_unlock(&pool->cb_lock); +} - if (time_before(jiffies, expires)) { - mod_timer(&pool->idle_timer, expires); - break; - } +#else - destroy_worker(worker); - ret = true; - } +static void worker_lock_callback(struct worker_pool *pool) { } +static void worker_unlock_callback(struct worker_pool *pool) { } +static void workqueue_callback_cancel_wait_running(struct worker_pool *pool) { } - return ret; -} +#endif /** * manage_workers - manage worker pool @@ -2029,65 +3112,31 @@ static bool maybe_destroy_workers(struct worker_pool *pool) * and may_start_working() is true. * * CONTEXT: - * spin_lock_irq(pool->lock) which may be released and regrabbed + * raw_spin_lock_irq(pool->lock) which may be released and regrabbed * multiple times. Does GFP_KERNEL allocations. * - * RETURNS: - * spin_lock_irq(pool->lock) which may be released and regrabbed - * multiple times. Does GFP_KERNEL allocations. + * Return: + * %false if the pool doesn't need management and the caller can safely + * start processing works, %true if management function was performed and + * the conditions that the caller verified before calling the function may + * no longer be true. */ static bool manage_workers(struct worker *worker) { struct worker_pool *pool = worker->pool; - bool ret = false; - /* - * Managership is governed by two mutexes - manager_arb and - * manager_mutex. manager_arb handles arbitration of manager role. - * Anyone who successfully grabs manager_arb wins the arbitration - * and becomes the manager. mutex_trylock() on pool->manager_arb - * failure while holding pool->lock reliably indicates that someone - * else is managing the pool and the worker which failed trylock - * can proceed to executing work items. This means that anyone - * grabbing manager_arb is responsible for actually performing - * manager duties. If manager_arb is grabbed and released without - * actual management, the pool may stall indefinitely. - * - * manager_mutex is used for exclusion of actual management - * operations. The holder of manager_mutex can be sure that none - * of management operations, including creation and destruction of - * workers, won't take place until the mutex is released. Because - * manager_mutex doesn't interfere with manager role arbitration, - * it is guaranteed that the pool's management, while may be - * delayed, won't be disturbed by someone else grabbing - * manager_mutex. - */ - if (!mutex_trylock(&pool->manager_arb)) - return ret; + if (pool->flags & POOL_MANAGER_ACTIVE) + return false; - /* - * With manager arbitration won, manager_mutex would be free in - * most cases. trylock first without dropping @pool->lock. - */ - if (unlikely(!mutex_trylock(&pool->manager_mutex))) { - spin_unlock_irq(&pool->lock); - mutex_lock(&pool->manager_mutex); - spin_lock_irq(&pool->lock); - ret = true; - } + pool->flags |= POOL_MANAGER_ACTIVE; + pool->manager = worker; - pool->flags &= ~POOL_MANAGE_WORKERS; + maybe_create_worker(pool); - /* - * Destroy and then create so that may_start_working() is true - * on return. - */ - ret |= maybe_destroy_workers(pool); - ret |= maybe_create_worker(pool); - - mutex_unlock(&pool->manager_mutex); - mutex_unlock(&pool->manager_arb); - return ret; + pool->manager = NULL; + pool->flags &= ~POOL_MANAGER_ACTIVE; + rcuwait_wake_up(&manager_wait); + return true; } /** @@ -2102,7 +3151,7 @@ static bool manage_workers(struct worker *worker) * call this function to process a work. * * CONTEXT: - * spin_lock_irq(pool->lock) which is released and regrabbed. + * raw_spin_lock_irq(pool->lock) which is released and regrabbed. */ static void process_one_work(struct worker *worker, struct work_struct *work) __releases(&pool->lock) @@ -2110,9 +3159,9 @@ __acquires(&pool->lock) { struct pool_workqueue *pwq = get_work_pwq(work); struct worker_pool *pool = worker->pool; - bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE; - int work_color; - struct worker *collision; + unsigned long work_data; + int lockdep_start_depth, rcu_start_depth; + bool bh_draining = pool->flags & POOL_BH_DRAINING; #ifdef CONFIG_LOCKDEP /* * It is permissible to free the struct work_struct from @@ -2125,50 +3174,45 @@ __acquires(&pool->lock) lockdep_copy_map(&lockdep_map, &work->lockdep_map); #endif - /* - * Ensure we're on the correct CPU. DISASSOCIATED test is - * necessary to avoid spurious warnings from rescuers servicing the - * unbound or a disassociated pool. - */ - WARN_ON_ONCE(!(worker->flags & WORKER_UNBOUND) && - !(pool->flags & POOL_DISASSOCIATED) && + /* ensure we're on the correct CPU */ + WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && raw_smp_processor_id() != pool->cpu); - /* - * A single work shouldn't be executed concurrently by - * multiple workers on a single cpu. Check whether anyone is - * already processing the work. If so, defer the work to the - * currently executing one. - */ - collision = find_worker_executing_work(pool, work); - if (unlikely(collision)) { - move_linked_works(work, &collision->scheduled, NULL); - return; - } - /* claim and dequeue */ debug_work_deactivate(work); hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); worker->current_work = work; worker->current_func = work->func; worker->current_pwq = pwq; - work_color = get_work_color(work); + if (worker->task) + worker->current_at = worker->task->se.sum_exec_runtime; + work_data = *work_data_bits(work); + worker->current_color = get_work_color(work_data); + + /* + * Record wq name for cmdline and debug reporting, may get + * overridden through set_worker_desc(). + */ + strscpy(worker->desc, pwq->wq->name, WORKER_DESC_LEN); list_del_init(&work->entry); /* - * CPU intensive works don't participate in concurrency - * management. They're the scheduler's responsibility. + * CPU intensive works don't participate in concurrency management. + * They're the scheduler's responsibility. This takes @worker out + * of concurrency management and the next code block will chain + * execution of the pending work items. */ - if (unlikely(cpu_intensive)) - worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); + if (unlikely(pwq->wq->flags & WQ_CPU_INTENSIVE)) + worker_set_flags(worker, WORKER_CPU_INTENSIVE); /* - * Unbound pool isn't concurrency managed and work items should be - * executed ASAP. Wake up another worker if necessary. + * Kick @pool if necessary. It's always noop for per-cpu worker pools + * since nr_running would always be >= 1 at this point. This is used to + * chain execution of the pending work items for WORKER_NOT_RUNNING + * workers such as the UNBOUND and CPU_INTENSIVE ones. */ - if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool)) - wake_up_worker(pool); + kick_pool(pool); /* * Record the last pool and clear PENDING which should be the last @@ -2176,44 +3220,98 @@ __acquires(&pool->lock) * PENDING and queued state changes happen together while IRQ is * disabled. */ - set_work_pool_and_clear_pending(work, pool->id); + set_work_pool_and_clear_pending(work, pool->id, pool_offq_flags(pool)); - spin_unlock_irq(&pool->lock); + pwq->stats[PWQ_STAT_STARTED]++; + raw_spin_unlock_irq(&pool->lock); - lock_map_acquire_read(&pwq->wq->lockdep_map); + rcu_start_depth = rcu_preempt_depth(); + lockdep_start_depth = lockdep_depth(current); + /* see drain_dead_softirq_workfn() */ + if (!bh_draining) + lock_map_acquire(pwq->wq->lockdep_map); lock_map_acquire(&lockdep_map); + /* + * Strictly speaking we should mark the invariant state without holding + * any locks, that is, before these two lock_map_acquire()'s. + * + * However, that would result in: + * + * A(W1) + * WFC(C) + * A(W1) + * C(C) + * + * Which would create W1->C->W1 dependencies, even though there is no + * actual deadlock possible. There are two solutions, using a + * read-recursive acquire on the work(queue) 'locks', but this will then + * hit the lockdep limitation on recursive locks, or simply discard + * these locks. + * + * AFAICT there is no possible deadlock scenario between the + * flush_work() and complete() primitives (except for single-threaded + * workqueues), so hiding them isn't a problem. + */ + lockdep_invariant_state(true); trace_workqueue_execute_start(work); worker->current_func(work); /* * While we must be careful to not use "work" after this, the trace * point will only record its address. */ - trace_workqueue_execute_end(work); - lock_map_release(&lockdep_map); - lock_map_release(&pwq->wq->lockdep_map); + trace_workqueue_execute_end(work, worker->current_func); - if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { - pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" - " last function: %pf\n", - current->comm, preempt_count(), task_pid_nr(current), + lock_map_release(&lockdep_map); + if (!bh_draining) + lock_map_release(pwq->wq->lockdep_map); + + if (unlikely((worker->task && in_atomic()) || + lockdep_depth(current) != lockdep_start_depth || + rcu_preempt_depth() != rcu_start_depth)) { + pr_err("BUG: workqueue leaked atomic, lock or RCU: %s[%d]\n" + " preempt=0x%08x lock=%d->%d RCU=%d->%d workfn=%ps\n", + current->comm, task_pid_nr(current), preempt_count(), + lockdep_start_depth, lockdep_depth(current), + rcu_start_depth, rcu_preempt_depth(), worker->current_func); debug_show_held_locks(current); dump_stack(); } - spin_lock_irq(&pool->lock); + /* + * The following prevents a kworker from hogging CPU on !PREEMPTION + * kernels, where a requeueing work item waiting for something to + * happen could deadlock with stop_machine as such work item could + * indefinitely requeue itself while all other CPUs are trapped in + * stop_machine. At the same time, report a quiescent RCU state so + * the same condition doesn't freeze RCU. + */ + if (worker->task) + cond_resched(); + + raw_spin_lock_irq(&pool->lock); - /* clear cpu intensive status */ - if (unlikely(cpu_intensive)) - worker_clr_flags(worker, WORKER_CPU_INTENSIVE); + pwq->stats[PWQ_STAT_COMPLETED]++; + + /* + * In addition to %WQ_CPU_INTENSIVE, @worker may also have been marked + * CPU intensive by wq_worker_tick() if @work hogged CPU longer than + * wq_cpu_intensive_thresh_us. Clear it. + */ + worker_clr_flags(worker, WORKER_CPU_INTENSIVE); + + /* tag the worker for identification in schedule() */ + worker->last_func = worker->current_func; /* we're done with it, release */ hash_del(&worker->hentry); worker->current_work = NULL; worker->current_func = NULL; worker->current_pwq = NULL; - worker->desc_valid = false; - pwq_dec_nr_in_flight(pwq, work_color); + worker->current_color = INT_MAX; + + /* must be the last step, see the function comment */ + pwq_dec_nr_in_flight(pwq, work_data); } /** @@ -2225,18 +3323,34 @@ __acquires(&pool->lock) * fetches a work from the top and executes it. * * CONTEXT: - * spin_lock_irq(pool->lock) which may be released and regrabbed + * raw_spin_lock_irq(pool->lock) which may be released and regrabbed * multiple times. */ static void process_scheduled_works(struct worker *worker) { - while (!list_empty(&worker->scheduled)) { - struct work_struct *work = list_first_entry(&worker->scheduled, - struct work_struct, entry); + struct work_struct *work; + bool first = true; + + while ((work = list_first_entry_or_null(&worker->scheduled, + struct work_struct, entry))) { + if (first) { + worker->pool->watchdog_ts = jiffies; + first = false; + } process_one_work(worker, work); } } +static void set_pf_worker(bool val) +{ + mutex_lock(&wq_pool_attach_mutex); + if (val) + current->flags |= PF_WQ_WORKER; + else + current->flags &= ~PF_WQ_WORKER; + mutex_unlock(&wq_pool_attach_mutex); +} + /** * worker_thread - the worker thread function * @__worker: self @@ -2246,6 +3360,8 @@ static void process_scheduled_works(struct worker *worker) * work items regardless of their specific target workqueue. The only * exception is work items which belong to workqueues with a rescuer which * will be explained in rescuer_thread(). + * + * Return: 0 */ static int worker_thread(void *__worker) { @@ -2253,15 +3369,20 @@ static int worker_thread(void *__worker) struct worker_pool *pool = worker->pool; /* tell the scheduler that this is a workqueue worker */ - worker->task->flags |= PF_WQ_WORKER; + set_pf_worker(true); woke_up: - spin_lock_irq(&pool->lock); + raw_spin_lock_irq(&pool->lock); /* am I supposed to die? */ if (unlikely(worker->flags & WORKER_DIE)) { - spin_unlock_irq(&pool->lock); - WARN_ON_ONCE(!list_empty(&worker->entry)); - worker->task->flags &= ~PF_WQ_WORKER; + raw_spin_unlock_irq(&pool->lock); + set_pf_worker(false); + /* + * The worker is dead and PF_WQ_WORKER is cleared, worker->pool + * shouldn't be accessed, reset it to NULL in case otherwise. + */ + worker->pool = NULL; + ida_free(&pool->worker_ida, worker->id); return 0; } @@ -2296,22 +3417,12 @@ recheck: list_first_entry(&pool->worklist, struct work_struct, entry); - if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { - /* optimization path, not strictly necessary */ - process_one_work(worker, work); - if (unlikely(!list_empty(&worker->scheduled))) - process_scheduled_works(worker); - } else { - move_linked_works(work, &worker->scheduled, NULL); + if (assign_work(work, worker, NULL)) process_scheduled_works(worker); - } } while (keep_working(pool)); - worker_set_flags(worker, WORKER_PREP, false); + worker_set_flags(worker, WORKER_PREP); sleep: - if (unlikely(need_to_manage_workers(pool)) && manage_workers(worker)) - goto recheck; - /* * pool->lock is held and there's no work to process and no need to * manage, sleep. Workers are woken up only while holding @@ -2320,12 +3431,33 @@ sleep: * event. */ worker_enter_idle(worker); - __set_current_state(TASK_INTERRUPTIBLE); - spin_unlock_irq(&pool->lock); + __set_current_state(TASK_IDLE); + raw_spin_unlock_irq(&pool->lock); schedule(); goto woke_up; } +static bool assign_rescuer_work(struct pool_workqueue *pwq, struct worker *rescuer) +{ + struct worker_pool *pool = pwq->pool; + struct work_struct *work, *n; + + /* need rescue? */ + if (!pwq->nr_active || !need_to_create_worker(pool)) + return false; + + /* + * Slurp in all works issued via this workqueue and + * process'em. + */ + list_for_each_entry_safe(work, n, &pool->worklist, entry) { + if (get_work_pwq(work) == pwq && assign_work(work, rescuer, &n)) + pwq->stats[PWQ_STAT_RESCUED]++; + } + + return !list_empty(&rescuer->scheduled); +} + /** * rescuer_thread - the rescuer thread function * @__rescuer: self @@ -2344,12 +3476,14 @@ sleep: * those works so that forward progress can be guaranteed. * * This should happen rarely. + * + * Return: 0 */ static int rescuer_thread(void *__rescuer) { struct worker *rescuer = __rescuer; struct workqueue_struct *wq = rescuer->rescue_wq; - struct list_head *scheduled = &rescuer->scheduled; + bool should_stop; set_user_nice(current, RESCUER_NICE_LEVEL); @@ -2357,59 +3491,90 @@ static int rescuer_thread(void *__rescuer) * Mark rescuer as worker too. As WORKER_PREP is never cleared, it * doesn't participate in concurrency management. */ - rescuer->task->flags |= PF_WQ_WORKER; + set_pf_worker(true); repeat: - set_current_state(TASK_INTERRUPTIBLE); + set_current_state(TASK_IDLE); - if (kthread_should_stop()) { - __set_current_state(TASK_RUNNING); - rescuer->task->flags &= ~PF_WQ_WORKER; - return 0; - } + /* + * By the time the rescuer is requested to stop, the workqueue + * shouldn't have any work pending, but @wq->maydays may still have + * pwq(s) queued. This can happen by non-rescuer workers consuming + * all the work items before the rescuer got to them. Go through + * @wq->maydays processing before acting on should_stop so that the + * list is always empty on exit. + */ + should_stop = kthread_should_stop(); /* see whether any pwq is asking for help */ - spin_lock_irq(&wq_mayday_lock); + raw_spin_lock_irq(&wq_mayday_lock); while (!list_empty(&wq->maydays)) { struct pool_workqueue *pwq = list_first_entry(&wq->maydays, struct pool_workqueue, mayday_node); struct worker_pool *pool = pwq->pool; - struct work_struct *work, *n; __set_current_state(TASK_RUNNING); list_del_init(&pwq->mayday_node); - spin_unlock_irq(&wq_mayday_lock); + raw_spin_unlock_irq(&wq_mayday_lock); - /* migrate to the target cpu if possible */ - worker_maybe_bind_and_lock(pool); - rescuer->pool = pool; + worker_attach_to_pool(rescuer, pool); + + raw_spin_lock_irq(&pool->lock); + + WARN_ON_ONCE(!list_empty(&rescuer->scheduled)); + + if (assign_rescuer_work(pwq, rescuer)) { + process_scheduled_works(rescuer); + + /* + * The above execution of rescued work items could + * have created more to rescue through + * pwq_activate_first_inactive() or chained + * queueing. Let's put @pwq back on mayday list so + * that such back-to-back work items, which may be + * being used to relieve memory pressure, don't + * incur MAYDAY_INTERVAL delay inbetween. + */ + if (pwq->nr_active && need_to_create_worker(pool)) { + raw_spin_lock(&wq_mayday_lock); + /* + * Queue iff somebody else hasn't queued it already. + */ + if (list_empty(&pwq->mayday_node)) { + get_pwq(pwq); + list_add_tail(&pwq->mayday_node, &wq->maydays); + } + raw_spin_unlock(&wq_mayday_lock); + } + } /* - * Slurp in all works issued via this workqueue and - * process'em. + * Leave this pool. Notify regular workers; otherwise, we end up + * with 0 concurrency and stalling the execution. */ - WARN_ON_ONCE(!list_empty(&rescuer->scheduled)); - list_for_each_entry_safe(work, n, &pool->worklist, entry) - if (get_work_pwq(work) == pwq) - move_linked_works(work, scheduled, &n); + kick_pool(pool); + + raw_spin_unlock_irq(&pool->lock); - process_scheduled_works(rescuer); + worker_detach_from_pool(rescuer); /* - * Leave this pool. If keep_working() is %true, notify a - * regular worker; otherwise, we end up with 0 concurrency - * and stalling the execution. + * Put the reference grabbed by send_mayday(). @pool might + * go away any time after it. */ - if (keep_working(pool)) - wake_up_worker(pool); + put_pwq_unlocked(pwq); - rescuer->pool = NULL; - spin_unlock(&pool->lock); - spin_lock(&wq_mayday_lock); + raw_spin_lock_irq(&wq_mayday_lock); } - spin_unlock_irq(&wq_mayday_lock); + raw_spin_unlock_irq(&wq_mayday_lock); + + if (should_stop) { + __set_current_state(TASK_RUNNING); + set_pf_worker(false); + return 0; + } /* rescuers should never participate in concurrency management */ WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); @@ -2417,9 +3582,182 @@ repeat: goto repeat; } +static void bh_worker(struct worker *worker) +{ + struct worker_pool *pool = worker->pool; + int nr_restarts = BH_WORKER_RESTARTS; + unsigned long end = jiffies + BH_WORKER_JIFFIES; + + worker_lock_callback(pool); + raw_spin_lock_irq(&pool->lock); + worker_leave_idle(worker); + + /* + * This function follows the structure of worker_thread(). See there for + * explanations on each step. + */ + if (!need_more_worker(pool)) + goto done; + + WARN_ON_ONCE(!list_empty(&worker->scheduled)); + worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND); + + do { + struct work_struct *work = + list_first_entry(&pool->worklist, + struct work_struct, entry); + + if (assign_work(work, worker, NULL)) + process_scheduled_works(worker); + } while (keep_working(pool) && + --nr_restarts && time_before(jiffies, end)); + + worker_set_flags(worker, WORKER_PREP); +done: + worker_enter_idle(worker); + kick_pool(pool); + raw_spin_unlock_irq(&pool->lock); + worker_unlock_callback(pool); +} + +/* + * TODO: Convert all tasklet users to workqueue and use softirq directly. + * + * This is currently called from tasklet[_hi]action() and thus is also called + * whenever there are tasklets to run. Let's do an early exit if there's nothing + * queued. Once conversion from tasklet is complete, the need_more_worker() test + * can be dropped. + * + * After full conversion, we'll add worker->softirq_action, directly use the + * softirq action and obtain the worker pointer from the softirq_action pointer. + */ +void workqueue_softirq_action(bool highpri) +{ + struct worker_pool *pool = + &per_cpu(bh_worker_pools, smp_processor_id())[highpri]; + if (need_more_worker(pool)) + bh_worker(list_first_entry(&pool->workers, struct worker, node)); +} + +struct wq_drain_dead_softirq_work { + struct work_struct work; + struct worker_pool *pool; + struct completion done; +}; + +static void drain_dead_softirq_workfn(struct work_struct *work) +{ + struct wq_drain_dead_softirq_work *dead_work = + container_of(work, struct wq_drain_dead_softirq_work, work); + struct worker_pool *pool = dead_work->pool; + bool repeat; + + /* + * @pool's CPU is dead and we want to execute its still pending work + * items from this BH work item which is running on a different CPU. As + * its CPU is dead, @pool can't be kicked and, as work execution path + * will be nested, a lockdep annotation needs to be suppressed. Mark + * @pool with %POOL_BH_DRAINING for the special treatments. + */ + raw_spin_lock_irq(&pool->lock); + pool->flags |= POOL_BH_DRAINING; + raw_spin_unlock_irq(&pool->lock); + + bh_worker(list_first_entry(&pool->workers, struct worker, node)); + + raw_spin_lock_irq(&pool->lock); + pool->flags &= ~POOL_BH_DRAINING; + repeat = need_more_worker(pool); + raw_spin_unlock_irq(&pool->lock); + + /* + * bh_worker() might hit consecutive execution limit and bail. If there + * still are pending work items, reschedule self and return so that we + * don't hog this CPU's BH. + */ + if (repeat) { + if (pool->attrs->nice == HIGHPRI_NICE_LEVEL) + queue_work(system_bh_highpri_wq, work); + else + queue_work(system_bh_wq, work); + } else { + complete(&dead_work->done); + } +} + +/* + * @cpu is dead. Drain the remaining BH work items on the current CPU. It's + * possible to allocate dead_work per CPU and avoid flushing. However, then we + * have to worry about draining overlapping with CPU coming back online or + * nesting (one CPU's dead_work queued on another CPU which is also dead and so + * on). Let's keep it simple and drain them synchronously. These are BH work + * items which shouldn't be requeued on the same pool. Shouldn't take long. + */ +void workqueue_softirq_dead(unsigned int cpu) +{ + int i; + + for (i = 0; i < NR_STD_WORKER_POOLS; i++) { + struct worker_pool *pool = &per_cpu(bh_worker_pools, cpu)[i]; + struct wq_drain_dead_softirq_work dead_work; + + if (!need_more_worker(pool)) + continue; + + INIT_WORK_ONSTACK(&dead_work.work, drain_dead_softirq_workfn); + dead_work.pool = pool; + init_completion(&dead_work.done); + + if (pool->attrs->nice == HIGHPRI_NICE_LEVEL) + queue_work(system_bh_highpri_wq, &dead_work.work); + else + queue_work(system_bh_wq, &dead_work.work); + + wait_for_completion(&dead_work.done); + destroy_work_on_stack(&dead_work.work); + } +} + +/** + * check_flush_dependency - check for flush dependency sanity + * @target_wq: workqueue being flushed + * @target_work: work item being flushed (NULL for workqueue flushes) + * @from_cancel: are we called from the work cancel path + * + * %current is trying to flush the whole @target_wq or @target_work on it. + * If this is not the cancel path (which implies work being flushed is either + * already running, or will not be at all), check if @target_wq doesn't have + * %WQ_MEM_RECLAIM and verify that %current is not reclaiming memory or running + * on a workqueue which doesn't have %WQ_MEM_RECLAIM as that can break forward- + * progress guarantee leading to a deadlock. + */ +static void check_flush_dependency(struct workqueue_struct *target_wq, + struct work_struct *target_work, + bool from_cancel) +{ + work_func_t target_func; + struct worker *worker; + + if (from_cancel || target_wq->flags & WQ_MEM_RECLAIM) + return; + + worker = current_wq_worker(); + target_func = target_work ? target_work->func : NULL; + + WARN_ONCE(current->flags & PF_MEMALLOC, + "workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%ps", + current->pid, current->comm, target_wq->name, target_func); + WARN_ONCE(worker && ((worker->current_pwq->wq->flags & + (WQ_MEM_RECLAIM | __WQ_LEGACY)) == WQ_MEM_RECLAIM), + "workqueue: WQ_MEM_RECLAIM %s:%ps is flushing !WQ_MEM_RECLAIM %s:%ps", + worker->current_pwq->wq->name, worker->current_func, + target_wq->name, target_func); +} + struct wq_barrier { struct work_struct work; struct completion done; + struct task_struct *task; /* purely informational */ }; static void wq_barrier_func(struct work_struct *work) @@ -2450,43 +3788,59 @@ static void wq_barrier_func(struct work_struct *work) * underneath us, so we can't reliably determine pwq from @target. * * CONTEXT: - * spin_lock_irq(pool->lock). + * raw_spin_lock_irq(pool->lock). */ static void insert_wq_barrier(struct pool_workqueue *pwq, struct wq_barrier *barr, struct work_struct *target, struct worker *worker) { + static __maybe_unused struct lock_class_key bh_key, thr_key; + unsigned int work_flags = 0; + unsigned int work_color; struct list_head *head; - unsigned int linked = 0; /* * debugobject calls are safe here even with pool->lock locked * as we know for sure that this will not trigger any of the * checks and call back into the fixup functions where we * might deadlock. + * + * BH and threaded workqueues need separate lockdep keys to avoid + * spuriously triggering "inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} + * usage". */ - INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); + INIT_WORK_ONSTACK_KEY(&barr->work, wq_barrier_func, + (pwq->wq->flags & WQ_BH) ? &bh_key : &thr_key); __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); - init_completion(&barr->done); + + init_completion_map(&barr->done, &target->lockdep_map); + + barr->task = current; + + /* The barrier work item does not participate in nr_active. */ + work_flags |= WORK_STRUCT_INACTIVE; /* * If @target is currently being executed, schedule the * barrier to the worker; otherwise, put it after @target. */ - if (worker) + if (worker) { head = worker->scheduled.next; - else { + work_color = worker->current_color; + } else { unsigned long *bits = work_data_bits(target); head = target->entry.next; /* there can already be other linked works, inherit and set */ - linked = *bits & WORK_STRUCT_LINKED; + work_flags |= *bits & WORK_STRUCT_LINKED; + work_color = get_work_color(*bits); __set_bit(WORK_STRUCT_LINKED_BIT, bits); } - debug_work_activate(&barr->work); - insert_work(pwq, &barr->work, head, - work_color_to_flags(WORK_NO_COLOR) | linked); + pwq->nr_in_flight[work_color]++; + work_flags |= work_color_to_flags(work_color); + + insert_work(pwq, &barr->work, head, work_flags); } /** @@ -2516,7 +3870,7 @@ static void insert_wq_barrier(struct pool_workqueue *pwq, * CONTEXT: * mutex_lock(wq->mutex). * - * RETURNS: + * Return: * %true if @flush_color >= 0 and there's something to flush. %false * otherwise. */ @@ -2525,16 +3879,28 @@ static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, { bool wait = false; struct pool_workqueue *pwq; + struct worker_pool *current_pool = NULL; if (flush_color >= 0) { WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush)); atomic_set(&wq->nr_pwqs_to_flush, 1); } + /* + * For unbound workqueue, pwqs will map to only a few pools. + * Most of the time, pwqs within the same pool will be linked + * sequentially to wq->pwqs by cpu index. So in the majority + * of pwq iters, the pool is the same, only doing lock/unlock + * if the pool has changed. This can largely reduce expensive + * lock operations. + */ for_each_pwq(pwq, wq) { - struct worker_pool *pool = pwq->pool; - - spin_lock_irq(&pool->lock); + if (current_pool != pwq->pool) { + if (likely(current_pool)) + raw_spin_unlock_irq(¤t_pool->lock); + current_pool = pwq->pool; + raw_spin_lock_irq(¤t_pool->lock); + } if (flush_color >= 0) { WARN_ON_ONCE(pwq->flush_color != -1); @@ -2551,33 +3917,69 @@ static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, pwq->work_color = work_color; } - spin_unlock_irq(&pool->lock); } + if (current_pool) + raw_spin_unlock_irq(¤t_pool->lock); + if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush)) complete(&wq->first_flusher->done); return wait; } +static void touch_wq_lockdep_map(struct workqueue_struct *wq) +{ +#ifdef CONFIG_LOCKDEP + if (unlikely(!wq->lockdep_map)) + return; + + if (wq->flags & WQ_BH) + local_bh_disable(); + + lock_map_acquire(wq->lockdep_map); + lock_map_release(wq->lockdep_map); + + if (wq->flags & WQ_BH) + local_bh_enable(); +#endif +} + +static void touch_work_lockdep_map(struct work_struct *work, + struct workqueue_struct *wq) +{ +#ifdef CONFIG_LOCKDEP + if (wq->flags & WQ_BH) + local_bh_disable(); + + lock_map_acquire(&work->lockdep_map); + lock_map_release(&work->lockdep_map); + + if (wq->flags & WQ_BH) + local_bh_enable(); +#endif +} + /** - * flush_workqueue - ensure that any scheduled work has run to completion. + * __flush_workqueue - ensure that any scheduled work has run to completion. * @wq: workqueue to flush * * This function sleeps until all work items which were queued on entry * have finished execution, but it is not livelocked by new incoming ones. */ -void flush_workqueue(struct workqueue_struct *wq) +void __flush_workqueue(struct workqueue_struct *wq) { struct wq_flusher this_flusher = { .list = LIST_HEAD_INIT(this_flusher.list), .flush_color = -1, - .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), + .done = COMPLETION_INITIALIZER_ONSTACK_MAP(this_flusher.done, (*wq->lockdep_map)), }; int next_color; - lock_map_acquire(&wq->lockdep_map); - lock_map_release(&wq->lockdep_map); + if (WARN_ON(!wq_online)) + return; + + touch_wq_lockdep_map(wq); mutex_lock(&wq->mutex); @@ -2624,6 +4026,8 @@ void flush_workqueue(struct workqueue_struct *wq) list_add_tail(&this_flusher.list, &wq->flusher_overflow); } + check_flush_dependency(wq, NULL, false); + mutex_unlock(&wq->mutex); wait_for_completion(&this_flusher.done); @@ -2634,7 +4038,7 @@ void flush_workqueue(struct workqueue_struct *wq) * First flushers are responsible for cascading flushes and * handling overflow. Non-first flushers can simply return. */ - if (wq->first_flusher != &this_flusher) + if (READ_ONCE(wq->first_flusher) != &this_flusher) return; mutex_lock(&wq->mutex); @@ -2643,7 +4047,7 @@ void flush_workqueue(struct workqueue_struct *wq) if (wq->first_flusher != &this_flusher) goto out_unlock; - wq->first_flusher = NULL; + WRITE_ONCE(wq->first_flusher, NULL); WARN_ON_ONCE(!list_empty(&this_flusher.list)); WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); @@ -2711,7 +4115,7 @@ void flush_workqueue(struct workqueue_struct *wq) out_unlock: mutex_unlock(&wq->mutex); } -EXPORT_SYMBOL_GPL(flush_workqueue); +EXPORT_SYMBOL(__flush_workqueue); /** * drain_workqueue - drain a workqueue @@ -2720,7 +4124,7 @@ EXPORT_SYMBOL_GPL(flush_workqueue); * Wait until the workqueue becomes empty. While draining is in progress, * only chain queueing is allowed. IOW, only currently pending or running * work items on @wq can queue further work items on it. @wq is flushed - * repeatedly until it becomes empty. The number of flushing is detemined + * repeatedly until it becomes empty. The number of flushing is determined * by the depth of chaining and should be relatively short. Whine if it * takes too long. */ @@ -2739,24 +4143,24 @@ void drain_workqueue(struct workqueue_struct *wq) wq->flags |= __WQ_DRAINING; mutex_unlock(&wq->mutex); reflush: - flush_workqueue(wq); + __flush_workqueue(wq); mutex_lock(&wq->mutex); for_each_pwq(pwq, wq) { bool drained; - spin_lock_irq(&pwq->pool->lock); - drained = !pwq->nr_active && list_empty(&pwq->delayed_works); - spin_unlock_irq(&pwq->pool->lock); + raw_spin_lock_irq(&pwq->pool->lock); + drained = pwq_is_empty(pwq); + raw_spin_unlock_irq(&pwq->pool->lock); if (drained) continue; if (++flush_cnt == 10 || (flush_cnt % 100 == 0 && flush_cnt <= 1000)) - pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n", - wq->name, flush_cnt); + pr_warn("workqueue %s: %s() isn't complete after %u tries\n", + wq->name, __func__, flush_cnt); mutex_unlock(&wq->mutex); goto reflush; @@ -2768,22 +4172,22 @@ reflush: } EXPORT_SYMBOL_GPL(drain_workqueue); -static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) +static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, + bool from_cancel) { struct worker *worker = NULL; struct worker_pool *pool; struct pool_workqueue *pwq; + struct workqueue_struct *wq; - might_sleep(); - - local_irq_disable(); + rcu_read_lock(); pool = get_work_pool(work); if (!pool) { - local_irq_enable(); + rcu_read_unlock(); return false; } - spin_lock(&pool->lock); + raw_spin_lock_irq(&pool->lock); /* see the comment in try_to_grab_pending() with the same code */ pwq = get_work_pwq(work); if (pwq) { @@ -2796,102 +4200,104 @@ static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) pwq = worker->current_pwq; } + wq = pwq->wq; + check_flush_dependency(wq, work, from_cancel); + insert_wq_barrier(pwq, barr, work, worker); - spin_unlock_irq(&pool->lock); + raw_spin_unlock_irq(&pool->lock); + + touch_work_lockdep_map(work, wq); /* - * If @max_active is 1 or rescuer is in use, flushing another work - * item on the same workqueue may lead to deadlock. Make sure the - * flusher is not running on the same workqueue by verifying write - * access. + * Force a lock recursion deadlock when using flush_work() inside a + * single-threaded or rescuer equipped workqueue. + * + * For single threaded workqueues the deadlock happens when the work + * is after the work issuing the flush_work(). For rescuer equipped + * workqueues the deadlock happens when the rescuer stalls, blocking + * forward progress. */ - if (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer) - lock_map_acquire(&pwq->wq->lockdep_map); - else - lock_map_acquire_read(&pwq->wq->lockdep_map); - lock_map_release(&pwq->wq->lockdep_map); + if (!from_cancel && (wq->saved_max_active == 1 || wq->rescuer)) + touch_wq_lockdep_map(wq); + rcu_read_unlock(); return true; already_gone: - spin_unlock_irq(&pool->lock); + raw_spin_unlock_irq(&pool->lock); + rcu_read_unlock(); return false; } -/** - * flush_work - wait for a work to finish executing the last queueing instance - * @work: the work to flush - * - * Wait until @work has finished execution. @work is guaranteed to be idle - * on return if it hasn't been requeued since flush started. - * - * RETURNS: - * %true if flush_work() waited for the work to finish execution, - * %false if it was already idle. - */ -bool flush_work(struct work_struct *work) +static bool __flush_work(struct work_struct *work, bool from_cancel) { struct wq_barrier barr; - lock_map_acquire(&work->lockdep_map); - lock_map_release(&work->lockdep_map); + if (WARN_ON(!wq_online)) + return false; - if (start_flush_work(work, &barr)) { - wait_for_completion(&barr.done); - destroy_work_on_stack(&barr.work); - return true; - } else { + if (WARN_ON(!work->func)) return false; - } -} -EXPORT_SYMBOL_GPL(flush_work); -static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) -{ - unsigned long flags; - int ret; + if (!start_flush_work(work, &barr, from_cancel)) + return false; - do { - ret = try_to_grab_pending(work, is_dwork, &flags); - /* - * If someone else is canceling, wait for the same event it - * would be waiting for before retrying. - */ - if (unlikely(ret == -ENOENT)) - flush_work(work); - } while (unlikely(ret < 0)); + /* + * start_flush_work() returned %true. If @from_cancel is set, we know + * that @work must have been executing during start_flush_work() and + * can't currently be queued. Its data must contain OFFQ bits. If @work + * was queued on a BH workqueue, we also know that it was running in the + * BH context and thus can be busy-waited. + */ + if (from_cancel) { + unsigned long data = *work_data_bits(work); - /* tell other tasks trying to grab @work to back off */ - mark_work_canceling(work); - local_irq_restore(flags); + if (!WARN_ON_ONCE(data & WORK_STRUCT_PWQ) && + (data & WORK_OFFQ_BH)) { + /* + * On RT, prevent a live lock when %current preempted + * soft interrupt processing by blocking on lock which + * is owned by the thread invoking the callback. + */ + while (!try_wait_for_completion(&barr.done)) { + if (IS_ENABLED(CONFIG_PREEMPT_RT)) { + struct worker_pool *pool; + + guard(rcu)(); + pool = get_work_pool(work); + if (pool) + workqueue_callback_cancel_wait_running(pool); + } else { + cpu_relax(); + } + } + goto out_destroy; + } + } - flush_work(work); - clear_work_data(work); - return ret; + wait_for_completion(&barr.done); + +out_destroy: + destroy_work_on_stack(&barr.work); + return true; } /** - * cancel_work_sync - cancel a work and wait for it to finish - * @work: the work to cancel - * - * Cancel @work and wait for its execution to finish. This function - * can be used even if the work re-queues itself or migrates to - * another workqueue. On return from this function, @work is - * guaranteed to be not pending or executing on any CPU. - * - * cancel_work_sync(&delayed_work->work) must not be used for - * delayed_work's. Use cancel_delayed_work_sync() instead. + * flush_work - wait for a work to finish executing the last queueing instance + * @work: the work to flush * - * The caller must ensure that the workqueue on which @work was last - * queued can't be destroyed before this function returns. + * Wait until @work has finished execution. @work is guaranteed to be idle + * on return if it hasn't been requeued since flush started. * - * RETURNS: - * %true if @work was pending, %false otherwise. + * Return: + * %true if flush_work() waited for the work to finish execution, + * %false if it was already idle. */ -bool cancel_work_sync(struct work_struct *work) +bool flush_work(struct work_struct *work) { - return __cancel_work_timer(work, false); + might_sleep(); + return __flush_work(work, false); } -EXPORT_SYMBOL_GPL(cancel_work_sync); +EXPORT_SYMBOL_GPL(flush_work); /** * flush_delayed_work - wait for a dwork to finish executing the last queueing @@ -2901,14 +4307,14 @@ EXPORT_SYMBOL_GPL(cancel_work_sync); * immediate execution. Like flush_work(), this function only * considers the last queueing instance of @dwork. * - * RETURNS: + * Return: * %true if flush_work() waited for the work to finish execution, * %false if it was already idle. */ bool flush_delayed_work(struct delayed_work *dwork) { local_irq_disable(); - if (del_timer_sync(&dwork->timer)) + if (timer_delete_sync(&dwork->timer)) __queue_work(dwork->cpu, dwork->wq, &dwork->work); local_irq_enable(); return flush_work(&dwork->work); @@ -2916,457 +4322,320 @@ bool flush_delayed_work(struct delayed_work *dwork) EXPORT_SYMBOL(flush_delayed_work); /** - * cancel_delayed_work - cancel a delayed work - * @dwork: delayed_work to cancel - * - * Kill off a pending delayed_work. Returns %true if @dwork was pending - * and canceled; %false if wasn't pending. Note that the work callback - * function may still be running on return, unless it returns %true and the - * work doesn't re-arm itself. Explicitly flush or use - * cancel_delayed_work_sync() to wait on it. + * flush_rcu_work - wait for a rwork to finish executing the last queueing + * @rwork: the rcu work to flush * - * This function is safe to call from any context including IRQ handler. + * Return: + * %true if flush_rcu_work() waited for the work to finish execution, + * %false if it was already idle. */ -bool cancel_delayed_work(struct delayed_work *dwork) +bool flush_rcu_work(struct rcu_work *rwork) { - unsigned long flags; - int ret; + if (test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&rwork->work))) { + rcu_barrier(); + flush_work(&rwork->work); + return true; + } else { + return flush_work(&rwork->work); + } +} +EXPORT_SYMBOL(flush_rcu_work); - do { - ret = try_to_grab_pending(&dwork->work, true, &flags); - } while (unlikely(ret == -EAGAIN)); +static void work_offqd_disable(struct work_offq_data *offqd) +{ + const unsigned long max = (1lu << WORK_OFFQ_DISABLE_BITS) - 1; - if (unlikely(ret < 0)) - return false; + if (likely(offqd->disable < max)) + offqd->disable++; + else + WARN_ONCE(true, "workqueue: work disable count overflowed\n"); +} - set_work_pool_and_clear_pending(&dwork->work, - get_work_pool_id(&dwork->work)); - local_irq_restore(flags); - return ret; +static void work_offqd_enable(struct work_offq_data *offqd) +{ + if (likely(offqd->disable > 0)) + offqd->disable--; + else + WARN_ONCE(true, "workqueue: work disable count underflowed\n"); } -EXPORT_SYMBOL(cancel_delayed_work); -/** - * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish - * @dwork: the delayed work cancel - * - * This is cancel_work_sync() for delayed works. - * - * RETURNS: - * %true if @dwork was pending, %false otherwise. - */ -bool cancel_delayed_work_sync(struct delayed_work *dwork) +static bool __cancel_work(struct work_struct *work, u32 cflags) { - return __cancel_work_timer(&dwork->work, true); + struct work_offq_data offqd; + unsigned long irq_flags; + int ret; + + ret = work_grab_pending(work, cflags, &irq_flags); + + work_offqd_unpack(&offqd, *work_data_bits(work)); + + if (cflags & WORK_CANCEL_DISABLE) + work_offqd_disable(&offqd); + + set_work_pool_and_clear_pending(work, offqd.pool_id, + work_offqd_pack_flags(&offqd)); + local_irq_restore(irq_flags); + return ret; } -EXPORT_SYMBOL(cancel_delayed_work_sync); -/** - * schedule_on_each_cpu - execute a function synchronously on each online CPU - * @func: the function to call - * - * schedule_on_each_cpu() executes @func on each online CPU using the - * system workqueue and blocks until all CPUs have completed. - * schedule_on_each_cpu() is very slow. - * - * RETURNS: - * 0 on success, -errno on failure. - */ -int schedule_on_each_cpu(work_func_t func) +static bool __cancel_work_sync(struct work_struct *work, u32 cflags) { - int cpu; - struct work_struct __percpu *works; + bool ret; - works = alloc_percpu(struct work_struct); - if (!works) - return -ENOMEM; + ret = __cancel_work(work, cflags | WORK_CANCEL_DISABLE); - get_online_cpus(); + if (*work_data_bits(work) & WORK_OFFQ_BH) + WARN_ON_ONCE(in_hardirq()); + else + might_sleep(); - for_each_online_cpu(cpu) { - struct work_struct *work = per_cpu_ptr(works, cpu); + /* + * Skip __flush_work() during early boot when we know that @work isn't + * executing. This allows canceling during early boot. + */ + if (wq_online) + __flush_work(work, true); - INIT_WORK(work, func); - schedule_work_on(cpu, work); - } + if (!(cflags & WORK_CANCEL_DISABLE)) + enable_work(work); - for_each_online_cpu(cpu) - flush_work(per_cpu_ptr(works, cpu)); + return ret; +} - put_online_cpus(); - free_percpu(works); - return 0; +/* + * See cancel_delayed_work() + */ +bool cancel_work(struct work_struct *work) +{ + return __cancel_work(work, 0); } +EXPORT_SYMBOL(cancel_work); /** - * flush_scheduled_work - ensure that any scheduled work has run to completion. - * - * Forces execution of the kernel-global workqueue and blocks until its - * completion. - * - * Think twice before calling this function! It's very easy to get into - * trouble if you don't take great care. Either of the following situations - * will lead to deadlock: + * cancel_work_sync - cancel a work and wait for it to finish + * @work: the work to cancel * - * One of the work items currently on the workqueue needs to acquire - * a lock held by your code or its caller. + * Cancel @work and wait for its execution to finish. This function can be used + * even if the work re-queues itself or migrates to another workqueue. On return + * from this function, @work is guaranteed to be not pending or executing on any + * CPU as long as there aren't racing enqueues. * - * Your code is running in the context of a work routine. + * cancel_work_sync(&delayed_work->work) must not be used for delayed_work's. + * Use cancel_delayed_work_sync() instead. * - * They will be detected by lockdep when they occur, but the first might not - * occur very often. It depends on what work items are on the workqueue and - * what locks they need, which you have no control over. + * Must be called from a sleepable context if @work was last queued on a non-BH + * workqueue. Can also be called from non-hardirq atomic contexts including BH + * if @work was last queued on a BH workqueue. * - * In most situations flushing the entire workqueue is overkill; you merely - * need to know that a particular work item isn't queued and isn't running. - * In such cases you should use cancel_delayed_work_sync() or - * cancel_work_sync() instead. + * Returns %true if @work was pending, %false otherwise. */ -void flush_scheduled_work(void) +bool cancel_work_sync(struct work_struct *work) { - flush_workqueue(system_wq); + return __cancel_work_sync(work, 0); } -EXPORT_SYMBOL(flush_scheduled_work); +EXPORT_SYMBOL_GPL(cancel_work_sync); /** - * execute_in_process_context - reliably execute the routine with user context - * @fn: the function to execute - * @ew: guaranteed storage for the execute work structure (must - * be available when the work executes) + * cancel_delayed_work - cancel a delayed work + * @dwork: delayed_work to cancel * - * Executes the function immediately if process context is available, - * otherwise schedules the function for delayed execution. + * Kill off a pending delayed_work. * - * Returns: 0 - function was executed - * 1 - function was scheduled for execution + * Return: %true if @dwork was pending and canceled; %false if it wasn't + * pending. + * + * Note: + * The work callback function may still be running on return, unless + * it returns %true and the work doesn't re-arm itself. Explicitly flush or + * use cancel_delayed_work_sync() to wait on it. + * + * This function is safe to call from any context including IRQ handler. */ -int execute_in_process_context(work_func_t fn, struct execute_work *ew) +bool cancel_delayed_work(struct delayed_work *dwork) { - if (!in_interrupt()) { - fn(&ew->work); - return 0; - } - - INIT_WORK(&ew->work, fn); - schedule_work(&ew->work); - - return 1; + return __cancel_work(&dwork->work, WORK_CANCEL_DELAYED); } -EXPORT_SYMBOL_GPL(execute_in_process_context); +EXPORT_SYMBOL(cancel_delayed_work); -#ifdef CONFIG_SYSFS -/* - * Workqueues with WQ_SYSFS flag set is visible to userland via - * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the - * following attributes. - * - * per_cpu RO bool : whether the workqueue is per-cpu or unbound - * max_active RW int : maximum number of in-flight work items +/** + * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish + * @dwork: the delayed work cancel * - * Unbound workqueues have the following extra attributes. + * This is cancel_work_sync() for delayed works. * - * id RO int : the associated pool ID - * nice RW int : nice value of the workers - * cpumask RW mask : bitmask of allowed CPUs for the workers + * Return: + * %true if @dwork was pending, %false otherwise. */ -struct wq_device { - struct workqueue_struct *wq; - struct device dev; -}; - -static struct workqueue_struct *dev_to_wq(struct device *dev) -{ - struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); - - return wq_dev->wq; -} - -static ssize_t wq_per_cpu_show(struct device *dev, - struct device_attribute *attr, char *buf) -{ - struct workqueue_struct *wq = dev_to_wq(dev); - - return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND)); -} - -static ssize_t wq_max_active_show(struct device *dev, - struct device_attribute *attr, char *buf) -{ - struct workqueue_struct *wq = dev_to_wq(dev); - - return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active); -} - -static ssize_t wq_max_active_store(struct device *dev, - struct device_attribute *attr, - const char *buf, size_t count) -{ - struct workqueue_struct *wq = dev_to_wq(dev); - int val; - - if (sscanf(buf, "%d", &val) != 1 || val <= 0) - return -EINVAL; - - workqueue_set_max_active(wq, val); - return count; -} - -static struct device_attribute wq_sysfs_attrs[] = { - __ATTR(per_cpu, 0444, wq_per_cpu_show, NULL), - __ATTR(max_active, 0644, wq_max_active_show, wq_max_active_store), - __ATTR_NULL, -}; - -static ssize_t wq_pool_ids_show(struct device *dev, - struct device_attribute *attr, char *buf) -{ - struct workqueue_struct *wq = dev_to_wq(dev); - const char *delim = ""; - int node, written = 0; - - rcu_read_lock_sched(); - for_each_node(node) { - written += scnprintf(buf + written, PAGE_SIZE - written, - "%s%d:%d", delim, node, - unbound_pwq_by_node(wq, node)->pool->id); - delim = " "; - } - written += scnprintf(buf + written, PAGE_SIZE - written, "\n"); - rcu_read_unlock_sched(); - - return written; -} - -static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr, - char *buf) -{ - struct workqueue_struct *wq = dev_to_wq(dev); - int written; - - mutex_lock(&wq->mutex); - written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice); - mutex_unlock(&wq->mutex); - - return written; -} - -/* prepare workqueue_attrs for sysfs store operations */ -static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq) +bool cancel_delayed_work_sync(struct delayed_work *dwork) { - struct workqueue_attrs *attrs; - - attrs = alloc_workqueue_attrs(GFP_KERNEL); - if (!attrs) - return NULL; - - mutex_lock(&wq->mutex); - copy_workqueue_attrs(attrs, wq->unbound_attrs); - mutex_unlock(&wq->mutex); - return attrs; + return __cancel_work_sync(&dwork->work, WORK_CANCEL_DELAYED); } +EXPORT_SYMBOL(cancel_delayed_work_sync); -static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, - const char *buf, size_t count) +/** + * disable_work - Disable and cancel a work item + * @work: work item to disable + * + * Disable @work by incrementing its disable count and cancel it if currently + * pending. As long as the disable count is non-zero, any attempt to queue @work + * will fail and return %false. The maximum supported disable depth is 2 to the + * power of %WORK_OFFQ_DISABLE_BITS, currently 65536. + * + * Can be called from any context. Returns %true if @work was pending, %false + * otherwise. + */ +bool disable_work(struct work_struct *work) { - struct workqueue_struct *wq = dev_to_wq(dev); - struct workqueue_attrs *attrs; - int ret; - - attrs = wq_sysfs_prep_attrs(wq); - if (!attrs) - return -ENOMEM; - - if (sscanf(buf, "%d", &attrs->nice) == 1 && - attrs->nice >= -20 && attrs->nice <= 19) - ret = apply_workqueue_attrs(wq, attrs); - else - ret = -EINVAL; - - free_workqueue_attrs(attrs); - return ret ?: count; + return __cancel_work(work, WORK_CANCEL_DISABLE); } +EXPORT_SYMBOL_GPL(disable_work); -static ssize_t wq_cpumask_show(struct device *dev, - struct device_attribute *attr, char *buf) +/** + * disable_work_sync - Disable, cancel and drain a work item + * @work: work item to disable + * + * Similar to disable_work() but also wait for @work to finish if currently + * executing. + * + * Must be called from a sleepable context if @work was last queued on a non-BH + * workqueue. Can also be called from non-hardirq atomic contexts including BH + * if @work was last queued on a BH workqueue. + * + * Returns %true if @work was pending, %false otherwise. + */ +bool disable_work_sync(struct work_struct *work) { - struct workqueue_struct *wq = dev_to_wq(dev); - int written; - - mutex_lock(&wq->mutex); - written = cpumask_scnprintf(buf, PAGE_SIZE, wq->unbound_attrs->cpumask); - mutex_unlock(&wq->mutex); - - written += scnprintf(buf + written, PAGE_SIZE - written, "\n"); - return written; + return __cancel_work_sync(work, WORK_CANCEL_DISABLE); } +EXPORT_SYMBOL_GPL(disable_work_sync); -static ssize_t wq_cpumask_store(struct device *dev, - struct device_attribute *attr, - const char *buf, size_t count) +/** + * enable_work - Enable a work item + * @work: work item to enable + * + * Undo disable_work[_sync]() by decrementing @work's disable count. @work can + * only be queued if its disable count is 0. + * + * Can be called from any context. Returns %true if the disable count reached 0. + * Otherwise, %false. + */ +bool enable_work(struct work_struct *work) { - struct workqueue_struct *wq = dev_to_wq(dev); - struct workqueue_attrs *attrs; - int ret; + struct work_offq_data offqd; + unsigned long irq_flags; - attrs = wq_sysfs_prep_attrs(wq); - if (!attrs) - return -ENOMEM; - - ret = cpumask_parse(buf, attrs->cpumask); - if (!ret) - ret = apply_workqueue_attrs(wq, attrs); - - free_workqueue_attrs(attrs); - return ret ?: count; -} - -static ssize_t wq_numa_show(struct device *dev, struct device_attribute *attr, - char *buf) -{ - struct workqueue_struct *wq = dev_to_wq(dev); - int written; + work_grab_pending(work, 0, &irq_flags); - mutex_lock(&wq->mutex); - written = scnprintf(buf, PAGE_SIZE, "%d\n", - !wq->unbound_attrs->no_numa); - mutex_unlock(&wq->mutex); + work_offqd_unpack(&offqd, *work_data_bits(work)); + work_offqd_enable(&offqd); + set_work_pool_and_clear_pending(work, offqd.pool_id, + work_offqd_pack_flags(&offqd)); + local_irq_restore(irq_flags); - return written; + return !offqd.disable; } +EXPORT_SYMBOL_GPL(enable_work); -static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr, - const char *buf, size_t count) +/** + * disable_delayed_work - Disable and cancel a delayed work item + * @dwork: delayed work item to disable + * + * disable_work() for delayed work items. + */ +bool disable_delayed_work(struct delayed_work *dwork) { - struct workqueue_struct *wq = dev_to_wq(dev); - struct workqueue_attrs *attrs; - int v, ret; - - attrs = wq_sysfs_prep_attrs(wq); - if (!attrs) - return -ENOMEM; - - ret = -EINVAL; - if (sscanf(buf, "%d", &v) == 1) { - attrs->no_numa = !v; - ret = apply_workqueue_attrs(wq, attrs); - } - - free_workqueue_attrs(attrs); - return ret ?: count; + return __cancel_work(&dwork->work, + WORK_CANCEL_DELAYED | WORK_CANCEL_DISABLE); } +EXPORT_SYMBOL_GPL(disable_delayed_work); -static struct device_attribute wq_sysfs_unbound_attrs[] = { - __ATTR(pool_ids, 0444, wq_pool_ids_show, NULL), - __ATTR(nice, 0644, wq_nice_show, wq_nice_store), - __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store), - __ATTR(numa, 0644, wq_numa_show, wq_numa_store), - __ATTR_NULL, -}; - -static struct bus_type wq_subsys = { - .name = "workqueue", - .dev_attrs = wq_sysfs_attrs, -}; - -static int __init wq_sysfs_init(void) +/** + * disable_delayed_work_sync - Disable, cancel and drain a delayed work item + * @dwork: delayed work item to disable + * + * disable_work_sync() for delayed work items. + */ +bool disable_delayed_work_sync(struct delayed_work *dwork) { - return subsys_virtual_register(&wq_subsys, NULL); + return __cancel_work_sync(&dwork->work, + WORK_CANCEL_DELAYED | WORK_CANCEL_DISABLE); } -core_initcall(wq_sysfs_init); +EXPORT_SYMBOL_GPL(disable_delayed_work_sync); -static void wq_device_release(struct device *dev) +/** + * enable_delayed_work - Enable a delayed work item + * @dwork: delayed work item to enable + * + * enable_work() for delayed work items. + */ +bool enable_delayed_work(struct delayed_work *dwork) { - struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); - - kfree(wq_dev); + return enable_work(&dwork->work); } +EXPORT_SYMBOL_GPL(enable_delayed_work); /** - * workqueue_sysfs_register - make a workqueue visible in sysfs - * @wq: the workqueue to register - * - * Expose @wq in sysfs under /sys/bus/workqueue/devices. - * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set - * which is the preferred method. + * schedule_on_each_cpu - execute a function synchronously on each online CPU + * @func: the function to call * - * Workqueue user should use this function directly iff it wants to apply - * workqueue_attrs before making the workqueue visible in sysfs; otherwise, - * apply_workqueue_attrs() may race against userland updating the - * attributes. + * schedule_on_each_cpu() executes @func on each online CPU using the + * system workqueue and blocks until all CPUs have completed. + * schedule_on_each_cpu() is very slow. * - * Returns 0 on success, -errno on failure. + * Return: + * 0 on success, -errno on failure. */ -int workqueue_sysfs_register(struct workqueue_struct *wq) +int schedule_on_each_cpu(work_func_t func) { - struct wq_device *wq_dev; - int ret; - - /* - * Adjusting max_active or creating new pwqs by applyting - * attributes breaks ordering guarantee. Disallow exposing ordered - * workqueues. - */ - if (WARN_ON(wq->flags & __WQ_ORDERED)) - return -EINVAL; + int cpu; + struct work_struct __percpu *works; - wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL); - if (!wq_dev) + works = alloc_percpu(struct work_struct); + if (!works) return -ENOMEM; - wq_dev->wq = wq; - wq_dev->dev.bus = &wq_subsys; - wq_dev->dev.init_name = wq->name; - wq_dev->dev.release = wq_device_release; + cpus_read_lock(); - /* - * unbound_attrs are created separately. Suppress uevent until - * everything is ready. - */ - dev_set_uevent_suppress(&wq_dev->dev, true); + for_each_online_cpu(cpu) { + struct work_struct *work = per_cpu_ptr(works, cpu); - ret = device_register(&wq_dev->dev); - if (ret) { - kfree(wq_dev); - wq->wq_dev = NULL; - return ret; + INIT_WORK(work, func); + schedule_work_on(cpu, work); } - if (wq->flags & WQ_UNBOUND) { - struct device_attribute *attr; - - for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) { - ret = device_create_file(&wq_dev->dev, attr); - if (ret) { - device_unregister(&wq_dev->dev); - wq->wq_dev = NULL; - return ret; - } - } - } + for_each_online_cpu(cpu) + flush_work(per_cpu_ptr(works, cpu)); - kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD); + cpus_read_unlock(); + free_percpu(works); return 0; } /** - * workqueue_sysfs_unregister - undo workqueue_sysfs_register() - * @wq: the workqueue to unregister + * execute_in_process_context - reliably execute the routine with user context + * @fn: the function to execute + * @ew: guaranteed storage for the execute work structure (must + * be available when the work executes) * - * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister. + * Executes the function immediately if process context is available, + * otherwise schedules the function for delayed execution. + * + * Return: 0 - function was executed + * 1 - function was scheduled for execution */ -static void workqueue_sysfs_unregister(struct workqueue_struct *wq) +int execute_in_process_context(work_func_t fn, struct execute_work *ew) { - struct wq_device *wq_dev = wq->wq_dev; + if (!in_interrupt()) { + fn(&ew->work); + return 0; + } - if (!wq->wq_dev) - return; + INIT_WORK(&ew->work, fn); + schedule_work(&ew->work); - wq->wq_dev = NULL; - device_unregister(&wq_dev->dev); + return 1; } -#else /* CONFIG_SYSFS */ -static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { } -#endif /* CONFIG_SYSFS */ +EXPORT_SYMBOL_GPL(execute_in_process_context); /** * free_workqueue_attrs - free a workqueue_attrs @@ -3378,28 +4647,33 @@ void free_workqueue_attrs(struct workqueue_attrs *attrs) { if (attrs) { free_cpumask_var(attrs->cpumask); + free_cpumask_var(attrs->__pod_cpumask); kfree(attrs); } } /** * alloc_workqueue_attrs - allocate a workqueue_attrs - * @gfp_mask: allocation mask to use * * Allocate a new workqueue_attrs, initialize with default settings and - * return it. Returns NULL on failure. + * return it. + * + * Return: The allocated new workqueue_attr on success. %NULL on failure. */ -struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask) +struct workqueue_attrs *alloc_workqueue_attrs_noprof(void) { struct workqueue_attrs *attrs; - attrs = kzalloc(sizeof(*attrs), gfp_mask); + attrs = kzalloc(sizeof(*attrs), GFP_KERNEL); if (!attrs) goto fail; - if (!alloc_cpumask_var(&attrs->cpumask, gfp_mask)) + if (!alloc_cpumask_var(&attrs->cpumask, GFP_KERNEL)) + goto fail; + if (!alloc_cpumask_var(&attrs->__pod_cpumask, GFP_KERNEL)) goto fail; cpumask_copy(attrs->cpumask, cpu_possible_mask); + attrs->affn_scope = WQ_AFFN_DFL; return attrs; fail: free_workqueue_attrs(attrs); @@ -3411,6 +4685,28 @@ static void copy_workqueue_attrs(struct workqueue_attrs *to, { to->nice = from->nice; cpumask_copy(to->cpumask, from->cpumask); + cpumask_copy(to->__pod_cpumask, from->__pod_cpumask); + to->affn_strict = from->affn_strict; + + /* + * Unlike hash and equality test, copying shouldn't ignore wq-only + * fields as copying is used for both pool and wq attrs. Instead, + * get_unbound_pool() explicitly clears the fields. + */ + to->affn_scope = from->affn_scope; + to->ordered = from->ordered; +} + +/* + * Some attrs fields are workqueue-only. Clear them for worker_pool's. See the + * comments in 'struct workqueue_attrs' definition. + */ +static void wqattrs_clear_for_pool(struct workqueue_attrs *attrs) +{ + attrs->affn_scope = WQ_AFFN_NR_TYPES; + attrs->ordered = false; + if (attrs->affn_strict) + cpumask_copy(attrs->cpumask, cpu_possible_mask); } /* hash value of the content of @attr */ @@ -3419,8 +4715,12 @@ static u32 wqattrs_hash(const struct workqueue_attrs *attrs) u32 hash = 0; hash = jhash_1word(attrs->nice, hash); - hash = jhash(cpumask_bits(attrs->cpumask), + hash = jhash_1word(attrs->affn_strict, hash); + hash = jhash(cpumask_bits(attrs->__pod_cpumask), BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash); + if (!attrs->affn_strict) + hash = jhash(cpumask_bits(attrs->cpumask), + BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash); return hash; } @@ -3430,57 +4730,221 @@ static bool wqattrs_equal(const struct workqueue_attrs *a, { if (a->nice != b->nice) return false; - if (!cpumask_equal(a->cpumask, b->cpumask)) + if (a->affn_strict != b->affn_strict) + return false; + if (!cpumask_equal(a->__pod_cpumask, b->__pod_cpumask)) + return false; + if (!a->affn_strict && !cpumask_equal(a->cpumask, b->cpumask)) return false; return true; } +/* Update @attrs with actually available CPUs */ +static void wqattrs_actualize_cpumask(struct workqueue_attrs *attrs, + const cpumask_t *unbound_cpumask) +{ + /* + * Calculate the effective CPU mask of @attrs given @unbound_cpumask. If + * @attrs->cpumask doesn't overlap with @unbound_cpumask, we fallback to + * @unbound_cpumask. + */ + cpumask_and(attrs->cpumask, attrs->cpumask, unbound_cpumask); + if (unlikely(cpumask_empty(attrs->cpumask))) + cpumask_copy(attrs->cpumask, unbound_cpumask); +} + +/* find wq_pod_type to use for @attrs */ +static const struct wq_pod_type * +wqattrs_pod_type(const struct workqueue_attrs *attrs) +{ + enum wq_affn_scope scope; + struct wq_pod_type *pt; + + /* to synchronize access to wq_affn_dfl */ + lockdep_assert_held(&wq_pool_mutex); + + if (attrs->affn_scope == WQ_AFFN_DFL) + scope = wq_affn_dfl; + else + scope = attrs->affn_scope; + + pt = &wq_pod_types[scope]; + + if (!WARN_ON_ONCE(attrs->affn_scope == WQ_AFFN_NR_TYPES) && + likely(pt->nr_pods)) + return pt; + + /* + * Before workqueue_init_topology(), only SYSTEM is available which is + * initialized in workqueue_init_early(). + */ + pt = &wq_pod_types[WQ_AFFN_SYSTEM]; + BUG_ON(!pt->nr_pods); + return pt; +} + /** * init_worker_pool - initialize a newly zalloc'd worker_pool * @pool: worker_pool to initialize * - * Initiailize a newly zalloc'd @pool. It also allocates @pool->attrs. - * Returns 0 on success, -errno on failure. Even on failure, all fields + * Initialize a newly zalloc'd @pool. It also allocates @pool->attrs. + * + * Return: 0 on success, -errno on failure. Even on failure, all fields * inside @pool proper are initialized and put_unbound_pool() can be called * on @pool safely to release it. */ static int init_worker_pool(struct worker_pool *pool) { - spin_lock_init(&pool->lock); + raw_spin_lock_init(&pool->lock); pool->id = -1; pool->cpu = -1; pool->node = NUMA_NO_NODE; pool->flags |= POOL_DISASSOCIATED; + pool->watchdog_ts = jiffies; INIT_LIST_HEAD(&pool->worklist); INIT_LIST_HEAD(&pool->idle_list); hash_init(pool->busy_hash); - init_timer_deferrable(&pool->idle_timer); - pool->idle_timer.function = idle_worker_timeout; - pool->idle_timer.data = (unsigned long)pool; + timer_setup(&pool->idle_timer, idle_worker_timeout, TIMER_DEFERRABLE); + INIT_WORK(&pool->idle_cull_work, idle_cull_fn); - setup_timer(&pool->mayday_timer, pool_mayday_timeout, - (unsigned long)pool); + timer_setup(&pool->mayday_timer, pool_mayday_timeout, 0); - mutex_init(&pool->manager_arb); - mutex_init(&pool->manager_mutex); - idr_init(&pool->worker_idr); + INIT_LIST_HEAD(&pool->workers); + ida_init(&pool->worker_ida); INIT_HLIST_NODE(&pool->hash_node); pool->refcnt = 1; +#ifdef CONFIG_PREEMPT_RT + spin_lock_init(&pool->cb_lock); +#endif /* shouldn't fail above this point */ - pool->attrs = alloc_workqueue_attrs(GFP_KERNEL); + pool->attrs = alloc_workqueue_attrs(); if (!pool->attrs) return -ENOMEM; + + wqattrs_clear_for_pool(pool->attrs); + + return 0; +} + +#ifdef CONFIG_LOCKDEP +static void wq_init_lockdep(struct workqueue_struct *wq) +{ + char *lock_name; + + lockdep_register_key(&wq->key); + lock_name = kasprintf(GFP_KERNEL, "%s%s", "(wq_completion)", wq->name); + if (!lock_name) + lock_name = wq->name; + + wq->lock_name = lock_name; + wq->lockdep_map = &wq->__lockdep_map; + lockdep_init_map(wq->lockdep_map, lock_name, &wq->key, 0); +} + +static void wq_unregister_lockdep(struct workqueue_struct *wq) +{ + if (wq->lockdep_map != &wq->__lockdep_map) + return; + + lockdep_unregister_key(&wq->key); +} + +static void wq_free_lockdep(struct workqueue_struct *wq) +{ + if (wq->lockdep_map != &wq->__lockdep_map) + return; + + if (wq->lock_name != wq->name) + kfree(wq->lock_name); +} +#else +static void wq_init_lockdep(struct workqueue_struct *wq) +{ +} + +static void wq_unregister_lockdep(struct workqueue_struct *wq) +{ +} + +static void wq_free_lockdep(struct workqueue_struct *wq) +{ +} +#endif + +static void free_node_nr_active(struct wq_node_nr_active **nna_ar) +{ + int node; + + for_each_node(node) { + kfree(nna_ar[node]); + nna_ar[node] = NULL; + } + + kfree(nna_ar[nr_node_ids]); + nna_ar[nr_node_ids] = NULL; +} + +static void init_node_nr_active(struct wq_node_nr_active *nna) +{ + nna->max = WQ_DFL_MIN_ACTIVE; + atomic_set(&nna->nr, 0); + raw_spin_lock_init(&nna->lock); + INIT_LIST_HEAD(&nna->pending_pwqs); +} + +/* + * Each node's nr_active counter will be accessed mostly from its own node and + * should be allocated in the node. + */ +static int alloc_node_nr_active(struct wq_node_nr_active **nna_ar) +{ + struct wq_node_nr_active *nna; + int node; + + for_each_node(node) { + nna = kzalloc_node(sizeof(*nna), GFP_KERNEL, node); + if (!nna) + goto err_free; + init_node_nr_active(nna); + nna_ar[node] = nna; + } + + /* [nr_node_ids] is used as the fallback */ + nna = kzalloc_node(sizeof(*nna), GFP_KERNEL, NUMA_NO_NODE); + if (!nna) + goto err_free; + init_node_nr_active(nna); + nna_ar[nr_node_ids] = nna; + return 0; + +err_free: + free_node_nr_active(nna_ar); + return -ENOMEM; +} + +static void rcu_free_wq(struct rcu_head *rcu) +{ + struct workqueue_struct *wq = + container_of(rcu, struct workqueue_struct, rcu); + + if (wq->flags & WQ_UNBOUND) + free_node_nr_active(wq->node_nr_active); + + wq_free_lockdep(wq); + free_percpu(wq->cpu_pwq); + free_workqueue_attrs(wq->unbound_attrs); + kfree(wq); } static void rcu_free_pool(struct rcu_head *rcu) { struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu); - idr_destroy(&pool->worker_idr); + ida_destroy(&pool->worker_ida); free_workqueue_attrs(pool->attrs); kfree(pool); } @@ -3489,7 +4953,7 @@ static void rcu_free_pool(struct rcu_head *rcu) * put_unbound_pool - put a worker_pool * @pool: worker_pool to put * - * Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU + * Put @pool. If its refcnt reaches zero, it gets destroyed in RCU * safe manner. get_unbound_pool() calls this function on its failure path * and this function should be able to release pools which went through, * successfully or not, init_worker_pool(). @@ -3499,6 +4963,7 @@ static void rcu_free_pool(struct rcu_head *rcu) static void put_unbound_pool(struct worker_pool *pool) { struct worker *worker; + LIST_HEAD(cull_list); lockdep_assert_held(&wq_pool_mutex); @@ -3506,7 +4971,7 @@ static void put_unbound_pool(struct worker_pool *pool) return; /* sanity checks */ - if (WARN_ON(!(pool->flags & POOL_DISASSOCIATED)) || + if (WARN_ON(!(pool->cpu < 0)) || WARN_ON(!list_empty(&pool->worklist))) return; @@ -3516,28 +4981,51 @@ static void put_unbound_pool(struct worker_pool *pool) hash_del(&pool->hash_node); /* - * Become the manager and destroy all workers. Grabbing - * manager_arb prevents @pool's workers from blocking on - * manager_mutex. + * Become the manager and destroy all workers. This prevents + * @pool's workers from blocking on attach_mutex. We're the last + * manager and @pool gets freed with the flag set. + * + * Having a concurrent manager is quite unlikely to happen as we can + * only get here with + * pwq->refcnt == pool->refcnt == 0 + * which implies no work queued to the pool, which implies no worker can + * become the manager. However a worker could have taken the role of + * manager before the refcnts dropped to 0, since maybe_create_worker() + * drops pool->lock */ - mutex_lock(&pool->manager_arb); - mutex_lock(&pool->manager_mutex); - spin_lock_irq(&pool->lock); + while (true) { + rcuwait_wait_event(&manager_wait, + !(pool->flags & POOL_MANAGER_ACTIVE), + TASK_UNINTERRUPTIBLE); + + mutex_lock(&wq_pool_attach_mutex); + raw_spin_lock_irq(&pool->lock); + if (!(pool->flags & POOL_MANAGER_ACTIVE)) { + pool->flags |= POOL_MANAGER_ACTIVE; + break; + } + raw_spin_unlock_irq(&pool->lock); + mutex_unlock(&wq_pool_attach_mutex); + } - while ((worker = first_worker(pool))) - destroy_worker(worker); + while ((worker = first_idle_worker(pool))) + set_worker_dying(worker, &cull_list); WARN_ON(pool->nr_workers || pool->nr_idle); + raw_spin_unlock_irq(&pool->lock); - spin_unlock_irq(&pool->lock); - mutex_unlock(&pool->manager_mutex); - mutex_unlock(&pool->manager_arb); + detach_dying_workers(&cull_list); + + mutex_unlock(&wq_pool_attach_mutex); + + reap_dying_workers(&cull_list); /* shut down the timers */ - del_timer_sync(&pool->idle_timer); - del_timer_sync(&pool->mayday_timer); + timer_delete_sync(&pool->idle_timer); + cancel_work_sync(&pool->idle_cull_work); + timer_delete_sync(&pool->mayday_timer); - /* sched-RCU protected to allow dereferences from get_work_pool() */ - call_rcu_sched(&pool->rcu, rcu_free_pool); + /* RCU protected to allow dereferences from get_work_pool() */ + call_rcu(&pool->rcu, rcu_free_pool); } /** @@ -3547,15 +5035,19 @@ static void put_unbound_pool(struct worker_pool *pool) * Obtain a worker_pool which has the same attributes as @attrs, bump the * reference count and return it. If there already is a matching * worker_pool, it will be used; otherwise, this function attempts to - * create a new one. On failure, returns NULL. + * create a new one. * * Should be called with wq_pool_mutex held. + * + * Return: On success, a worker_pool with the same attributes as @attrs. + * On failure, %NULL. */ static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) { + struct wq_pod_type *pt = &wq_pod_types[WQ_AFFN_NUMA]; u32 hash = wqattrs_hash(attrs); struct worker_pool *pool; - int node; + int pod, node = NUMA_NO_NODE; lockdep_assert_held(&wq_pool_mutex); @@ -3563,42 +5055,37 @@ static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) { if (wqattrs_equal(pool->attrs, attrs)) { pool->refcnt++; - goto out_unlock; + return pool; + } + } + + /* If __pod_cpumask is contained inside a NUMA pod, that's our node */ + for (pod = 0; pod < pt->nr_pods; pod++) { + if (cpumask_subset(attrs->__pod_cpumask, pt->pod_cpus[pod])) { + node = pt->pod_node[pod]; + break; } } /* nope, create a new one */ - pool = kzalloc(sizeof(*pool), GFP_KERNEL); + pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, node); if (!pool || init_worker_pool(pool) < 0) goto fail; - if (workqueue_freezing) - pool->flags |= POOL_FREEZING; - - lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */ + pool->node = node; copy_workqueue_attrs(pool->attrs, attrs); - - /* if cpumask is contained inside a NUMA node, we belong to that node */ - if (wq_numa_enabled) { - for_each_node(node) { - if (cpumask_subset(pool->attrs->cpumask, - wq_numa_possible_cpumask[node])) { - pool->node = node; - break; - } - } - } + wqattrs_clear_for_pool(pool->attrs); if (worker_pool_assign_id(pool) < 0) goto fail; /* create and start the initial worker */ - if (create_and_start_worker(pool) < 0) + if (wq_online && !create_worker(pool)) goto fail; /* install */ hash_add(unbound_pool_hash, &pool->hash_node, hash); -out_unlock: + return pool; fail: if (pool) @@ -3606,99 +5093,68 @@ fail: return NULL; } -static void rcu_free_pwq(struct rcu_head *rcu) -{ - kmem_cache_free(pwq_cache, - container_of(rcu, struct pool_workqueue, rcu)); -} - /* - * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt - * and needs to be destroyed. + * Scheduled on pwq_release_worker by put_pwq() when an unbound pwq hits zero + * refcnt and needs to be destroyed. */ -static void pwq_unbound_release_workfn(struct work_struct *work) +static void pwq_release_workfn(struct kthread_work *work) { struct pool_workqueue *pwq = container_of(work, struct pool_workqueue, - unbound_release_work); + release_work); struct workqueue_struct *wq = pwq->wq; struct worker_pool *pool = pwq->pool; - bool is_last; - - if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND))) - return; + bool is_last = false; /* - * Unlink @pwq. Synchronization against wq->mutex isn't strictly - * necessary on release but do it anyway. It's easier to verify - * and consistent with the linking path. + * When @pwq is not linked, it doesn't hold any reference to the + * @wq, and @wq is invalid to access. */ - mutex_lock(&wq->mutex); - list_del_rcu(&pwq->pwqs_node); - is_last = list_empty(&wq->pwqs); - mutex_unlock(&wq->mutex); - - mutex_lock(&wq_pool_mutex); - put_unbound_pool(pool); - mutex_unlock(&wq_pool_mutex); + if (!list_empty(&pwq->pwqs_node)) { + mutex_lock(&wq->mutex); + list_del_rcu(&pwq->pwqs_node); + is_last = list_empty(&wq->pwqs); - call_rcu_sched(&pwq->rcu, rcu_free_pwq); + /* + * For ordered workqueue with a plugged dfl_pwq, restart it now. + */ + if (!is_last && (wq->flags & __WQ_ORDERED)) + unplug_oldest_pwq(wq); - /* - * If we're the last pwq going away, @wq is already dead and no one - * is gonna access it anymore. Free it. - */ - if (is_last) { - free_workqueue_attrs(wq->unbound_attrs); - kfree(wq); + mutex_unlock(&wq->mutex); } -} -/** - * pwq_adjust_max_active - update a pwq's max_active to the current setting - * @pwq: target pool_workqueue - * - * If @pwq isn't freezing, set @pwq->max_active to the associated - * workqueue's saved_max_active and activate delayed work items - * accordingly. If @pwq is freezing, clear @pwq->max_active to zero. - */ -static void pwq_adjust_max_active(struct pool_workqueue *pwq) -{ - struct workqueue_struct *wq = pwq->wq; - bool freezable = wq->flags & WQ_FREEZABLE; - - /* for @wq->saved_max_active */ - lockdep_assert_held(&wq->mutex); - - /* fast exit for non-freezable wqs */ - if (!freezable && pwq->max_active == wq->saved_max_active) - return; + if (wq->flags & WQ_UNBOUND) { + mutex_lock(&wq_pool_mutex); + put_unbound_pool(pool); + mutex_unlock(&wq_pool_mutex); + } - spin_lock_irq(&pwq->pool->lock); + if (!list_empty(&pwq->pending_node)) { + struct wq_node_nr_active *nna = + wq_node_nr_active(pwq->wq, pwq->pool->node); - if (!freezable || !(pwq->pool->flags & POOL_FREEZING)) { - pwq->max_active = wq->saved_max_active; + raw_spin_lock_irq(&nna->lock); + list_del_init(&pwq->pending_node); + raw_spin_unlock_irq(&nna->lock); + } - while (!list_empty(&pwq->delayed_works) && - pwq->nr_active < pwq->max_active) - pwq_activate_first_delayed(pwq); + kfree_rcu(pwq, rcu); - /* - * Need to kick a worker after thawed or an unbound wq's - * max_active is bumped. It's a slow path. Do it always. - */ - wake_up_worker(pwq->pool); - } else { - pwq->max_active = 0; + /* + * If we're the last pwq going away, @wq is already dead and no one + * is gonna access it anymore. Schedule RCU free. + */ + if (is_last) { + wq_unregister_lockdep(wq); + call_rcu(&wq->rcu, rcu_free_wq); } - - spin_unlock_irq(&pwq->pool->lock); } -/* initialize newly alloced @pwq which is associated with @wq and @pool */ +/* initialize newly allocated @pwq which is associated with @wq and @pool */ static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq, struct worker_pool *pool) { - BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK); + BUG_ON((unsigned long)pwq & ~WORK_STRUCT_PWQ_MASK); memset(pwq, 0, sizeof(*pwq)); @@ -3706,10 +5162,11 @@ static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq, pwq->wq = wq; pwq->flush_color = -1; pwq->refcnt = 1; - INIT_LIST_HEAD(&pwq->delayed_works); + INIT_LIST_HEAD(&pwq->inactive_works); + INIT_LIST_HEAD(&pwq->pending_node); INIT_LIST_HEAD(&pwq->pwqs_node); INIT_LIST_HEAD(&pwq->mayday_node); - INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn); + kthread_init_work(&pwq->release_work, pwq_release_workfn); } /* sync @pwq with the current state of its associated wq and link it */ @@ -3723,17 +5180,11 @@ static void link_pwq(struct pool_workqueue *pwq) if (!list_empty(&pwq->pwqs_node)) return; - /* - * Set the matching work_color. This is synchronized with - * wq->mutex to avoid confusing flush_workqueue(). - */ + /* set the matching work_color */ pwq->work_color = wq->work_color; - /* sync max_active to the current setting */ - pwq_adjust_max_active(pwq); - /* link in @pwq */ - list_add_rcu(&pwq->pwqs_node, &wq->pwqs); + list_add_tail_rcu(&pwq->pwqs_node, &wq->pwqs); } /* obtain a pool matching @attr and create a pwq associating the pool and @wq */ @@ -3759,231 +5210,253 @@ static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq, return pwq; } -/* undo alloc_unbound_pwq(), used only in the error path */ -static void free_unbound_pwq(struct pool_workqueue *pwq) +static void apply_wqattrs_lock(void) { - lockdep_assert_held(&wq_pool_mutex); + mutex_lock(&wq_pool_mutex); +} - if (pwq) { - put_unbound_pool(pwq->pool); - kmem_cache_free(pwq_cache, pwq); - } +static void apply_wqattrs_unlock(void) +{ + mutex_unlock(&wq_pool_mutex); } /** - * wq_calc_node_mask - calculate a wq_attrs' cpumask for the specified node - * @attrs: the wq_attrs of interest - * @node: the target NUMA node - * @cpu_going_down: if >= 0, the CPU to consider as offline - * @cpumask: outarg, the resulting cpumask - * - * Calculate the cpumask a workqueue with @attrs should use on @node. If - * @cpu_going_down is >= 0, that cpu is considered offline during - * calculation. The result is stored in @cpumask. This function returns - * %true if the resulting @cpumask is different from @attrs->cpumask, - * %false if equal. - * - * If NUMA affinity is not enabled, @attrs->cpumask is always used. If - * enabled and @node has online CPUs requested by @attrs, the returned - * cpumask is the intersection of the possible CPUs of @node and - * @attrs->cpumask. - * - * The caller is responsible for ensuring that the cpumask of @node stays - * stable. - */ -static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node, - int cpu_going_down, cpumask_t *cpumask) -{ - if (!wq_numa_enabled || attrs->no_numa) - goto use_dfl; - - /* does @node have any online CPUs @attrs wants? */ - cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask); - if (cpu_going_down >= 0) - cpumask_clear_cpu(cpu_going_down, cpumask); - - if (cpumask_empty(cpumask)) - goto use_dfl; - - /* yeap, return possible CPUs in @node that @attrs wants */ - cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]); - return !cpumask_equal(cpumask, attrs->cpumask); - -use_dfl: - cpumask_copy(cpumask, attrs->cpumask); - return false; + * wq_calc_pod_cpumask - calculate a wq_attrs' cpumask for a pod + * @attrs: the wq_attrs of the default pwq of the target workqueue + * @cpu: the target CPU + * + * Calculate the cpumask a workqueue with @attrs should use on @pod. + * The result is stored in @attrs->__pod_cpumask. + * + * If pod affinity is not enabled, @attrs->cpumask is always used. If enabled + * and @pod has online CPUs requested by @attrs, the returned cpumask is the + * intersection of the possible CPUs of @pod and @attrs->cpumask. + * + * The caller is responsible for ensuring that the cpumask of @pod stays stable. + */ +static void wq_calc_pod_cpumask(struct workqueue_attrs *attrs, int cpu) +{ + const struct wq_pod_type *pt = wqattrs_pod_type(attrs); + int pod = pt->cpu_pod[cpu]; + + /* calculate possible CPUs in @pod that @attrs wants */ + cpumask_and(attrs->__pod_cpumask, pt->pod_cpus[pod], attrs->cpumask); + /* does @pod have any online CPUs @attrs wants? */ + if (!cpumask_intersects(attrs->__pod_cpumask, wq_online_cpumask)) { + cpumask_copy(attrs->__pod_cpumask, attrs->cpumask); + return; + } } -/* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */ -static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq, - int node, - struct pool_workqueue *pwq) +/* install @pwq into @wq and return the old pwq, @cpu < 0 for dfl_pwq */ +static struct pool_workqueue *install_unbound_pwq(struct workqueue_struct *wq, + int cpu, struct pool_workqueue *pwq) { + struct pool_workqueue __rcu **slot = unbound_pwq_slot(wq, cpu); struct pool_workqueue *old_pwq; + lockdep_assert_held(&wq_pool_mutex); lockdep_assert_held(&wq->mutex); /* link_pwq() can handle duplicate calls */ link_pwq(pwq); - old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); - rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq); + old_pwq = rcu_access_pointer(*slot); + rcu_assign_pointer(*slot, pwq); return old_pwq; } -/** - * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue - * @wq: the target workqueue - * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs() - * - * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA - * machines, this function maps a separate pwq to each NUMA node with - * possibles CPUs in @attrs->cpumask so that work items are affine to the - * NUMA node it was issued on. Older pwqs are released as in-flight work - * items finish. Note that a work item which repeatedly requeues itself - * back-to-back will stay on its current pwq. - * - * Performs GFP_KERNEL allocations. Returns 0 on success and -errno on - * failure. - */ -int apply_workqueue_attrs(struct workqueue_struct *wq, - const struct workqueue_attrs *attrs) +/* context to store the prepared attrs & pwqs before applying */ +struct apply_wqattrs_ctx { + struct workqueue_struct *wq; /* target workqueue */ + struct workqueue_attrs *attrs; /* attrs to apply */ + struct list_head list; /* queued for batching commit */ + struct pool_workqueue *dfl_pwq; + struct pool_workqueue *pwq_tbl[]; +}; + +/* free the resources after success or abort */ +static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx *ctx) { - struct workqueue_attrs *new_attrs, *tmp_attrs; - struct pool_workqueue **pwq_tbl, *dfl_pwq; - int node, ret; + if (ctx) { + int cpu; - /* only unbound workqueues can change attributes */ - if (WARN_ON(!(wq->flags & WQ_UNBOUND))) - return -EINVAL; + for_each_possible_cpu(cpu) + put_pwq_unlocked(ctx->pwq_tbl[cpu]); + put_pwq_unlocked(ctx->dfl_pwq); - /* creating multiple pwqs breaks ordering guarantee */ - if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs))) - return -EINVAL; + free_workqueue_attrs(ctx->attrs); - pwq_tbl = kzalloc(wq_numa_tbl_len * sizeof(pwq_tbl[0]), GFP_KERNEL); - new_attrs = alloc_workqueue_attrs(GFP_KERNEL); - tmp_attrs = alloc_workqueue_attrs(GFP_KERNEL); - if (!pwq_tbl || !new_attrs || !tmp_attrs) - goto enomem; + kfree(ctx); + } +} - /* make a copy of @attrs and sanitize it */ - copy_workqueue_attrs(new_attrs, attrs); - cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask); +/* allocate the attrs and pwqs for later installation */ +static struct apply_wqattrs_ctx * +apply_wqattrs_prepare(struct workqueue_struct *wq, + const struct workqueue_attrs *attrs, + const cpumask_var_t unbound_cpumask) +{ + struct apply_wqattrs_ctx *ctx; + struct workqueue_attrs *new_attrs; + int cpu; - /* - * We may create multiple pwqs with differing cpumasks. Make a - * copy of @new_attrs which will be modified and used to obtain - * pools. - */ - copy_workqueue_attrs(tmp_attrs, new_attrs); + lockdep_assert_held(&wq_pool_mutex); - /* - * CPUs should stay stable across pwq creations and installations. - * Pin CPUs, determine the target cpumask for each node and create - * pwqs accordingly. - */ - get_online_cpus(); + if (WARN_ON(attrs->affn_scope < 0 || + attrs->affn_scope >= WQ_AFFN_NR_TYPES)) + return ERR_PTR(-EINVAL); - mutex_lock(&wq_pool_mutex); + ctx = kzalloc(struct_size(ctx, pwq_tbl, nr_cpu_ids), GFP_KERNEL); + + new_attrs = alloc_workqueue_attrs(); + if (!ctx || !new_attrs) + goto out_free; /* * If something goes wrong during CPU up/down, we'll fall back to * the default pwq covering whole @attrs->cpumask. Always create * it even if we don't use it immediately. */ - dfl_pwq = alloc_unbound_pwq(wq, new_attrs); - if (!dfl_pwq) - goto enomem_pwq; + copy_workqueue_attrs(new_attrs, attrs); + wqattrs_actualize_cpumask(new_attrs, unbound_cpumask); + cpumask_copy(new_attrs->__pod_cpumask, new_attrs->cpumask); + ctx->dfl_pwq = alloc_unbound_pwq(wq, new_attrs); + if (!ctx->dfl_pwq) + goto out_free; - for_each_node(node) { - if (wq_calc_node_cpumask(attrs, node, -1, tmp_attrs->cpumask)) { - pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs); - if (!pwq_tbl[node]) - goto enomem_pwq; + for_each_possible_cpu(cpu) { + if (new_attrs->ordered) { + ctx->dfl_pwq->refcnt++; + ctx->pwq_tbl[cpu] = ctx->dfl_pwq; } else { - dfl_pwq->refcnt++; - pwq_tbl[node] = dfl_pwq; + wq_calc_pod_cpumask(new_attrs, cpu); + ctx->pwq_tbl[cpu] = alloc_unbound_pwq(wq, new_attrs); + if (!ctx->pwq_tbl[cpu]) + goto out_free; } } - mutex_unlock(&wq_pool_mutex); + /* save the user configured attrs and sanitize it. */ + copy_workqueue_attrs(new_attrs, attrs); + cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask); + cpumask_copy(new_attrs->__pod_cpumask, new_attrs->cpumask); + ctx->attrs = new_attrs; + + /* + * For initialized ordered workqueues, there should only be one pwq + * (dfl_pwq). Set the plugged flag of ctx->dfl_pwq to suspend execution + * of newly queued work items until execution of older work items in + * the old pwq's have completed. + */ + if ((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs)) + ctx->dfl_pwq->plugged = true; + + ctx->wq = wq; + return ctx; + +out_free: + free_workqueue_attrs(new_attrs); + apply_wqattrs_cleanup(ctx); + return ERR_PTR(-ENOMEM); +} + +/* set attrs and install prepared pwqs, @ctx points to old pwqs on return */ +static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx) +{ + int cpu; /* all pwqs have been created successfully, let's install'em */ - mutex_lock(&wq->mutex); + mutex_lock(&ctx->wq->mutex); - copy_workqueue_attrs(wq->unbound_attrs, new_attrs); + copy_workqueue_attrs(ctx->wq->unbound_attrs, ctx->attrs); - /* save the previous pwq and install the new one */ - for_each_node(node) - pwq_tbl[node] = numa_pwq_tbl_install(wq, node, pwq_tbl[node]); + /* save the previous pwqs and install the new ones */ + for_each_possible_cpu(cpu) + ctx->pwq_tbl[cpu] = install_unbound_pwq(ctx->wq, cpu, + ctx->pwq_tbl[cpu]); + ctx->dfl_pwq = install_unbound_pwq(ctx->wq, -1, ctx->dfl_pwq); - /* @dfl_pwq might not have been used, ensure it's linked */ - link_pwq(dfl_pwq); - swap(wq->dfl_pwq, dfl_pwq); + /* update node_nr_active->max */ + wq_update_node_max_active(ctx->wq, -1); - mutex_unlock(&wq->mutex); + mutex_unlock(&ctx->wq->mutex); +} - /* put the old pwqs */ - for_each_node(node) - put_pwq_unlocked(pwq_tbl[node]); - put_pwq_unlocked(dfl_pwq); +static int apply_workqueue_attrs_locked(struct workqueue_struct *wq, + const struct workqueue_attrs *attrs) +{ + struct apply_wqattrs_ctx *ctx; - put_online_cpus(); - ret = 0; - /* fall through */ -out_free: - free_workqueue_attrs(tmp_attrs); - free_workqueue_attrs(new_attrs); - kfree(pwq_tbl); - return ret; + /* only unbound workqueues can change attributes */ + if (WARN_ON(!(wq->flags & WQ_UNBOUND))) + return -EINVAL; + + ctx = apply_wqattrs_prepare(wq, attrs, wq_unbound_cpumask); + if (IS_ERR(ctx)) + return PTR_ERR(ctx); + + /* the ctx has been prepared successfully, let's commit it */ + apply_wqattrs_commit(ctx); + apply_wqattrs_cleanup(ctx); + + return 0; +} -enomem_pwq: - free_unbound_pwq(dfl_pwq); - for_each_node(node) - if (pwq_tbl && pwq_tbl[node] != dfl_pwq) - free_unbound_pwq(pwq_tbl[node]); +/** + * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue + * @wq: the target workqueue + * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs() + * + * Apply @attrs to an unbound workqueue @wq. Unless disabled, this function maps + * a separate pwq to each CPU pod with possibles CPUs in @attrs->cpumask so that + * work items are affine to the pod it was issued on. Older pwqs are released as + * in-flight work items finish. Note that a work item which repeatedly requeues + * itself back-to-back will stay on its current pwq. + * + * Performs GFP_KERNEL allocations. + * + * Return: 0 on success and -errno on failure. + */ +int apply_workqueue_attrs(struct workqueue_struct *wq, + const struct workqueue_attrs *attrs) +{ + int ret; + + mutex_lock(&wq_pool_mutex); + ret = apply_workqueue_attrs_locked(wq, attrs); mutex_unlock(&wq_pool_mutex); - put_online_cpus(); -enomem: - ret = -ENOMEM; - goto out_free; + + return ret; } /** - * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug + * unbound_wq_update_pwq - update a pwq slot for CPU hot[un]plug * @wq: the target workqueue - * @cpu: the CPU coming up or going down - * @online: whether @cpu is coming up or going down + * @cpu: the CPU to update the pwq slot for * * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and - * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of - * @wq accordingly. - * - * If NUMA affinity can't be adjusted due to memory allocation failure, it - * falls back to @wq->dfl_pwq which may not be optimal but is always - * correct. - * - * Note that when the last allowed CPU of a NUMA node goes offline for a - * workqueue with a cpumask spanning multiple nodes, the workers which were - * already executing the work items for the workqueue will lose their CPU - * affinity and may execute on any CPU. This is similar to how per-cpu - * workqueues behave on CPU_DOWN. If a workqueue user wants strict - * affinity, it's the user's responsibility to flush the work item from - * CPU_DOWN_PREPARE. - */ -static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu, - bool online) -{ - int node = cpu_to_node(cpu); - int cpu_off = online ? -1 : cpu; + * %CPU_DOWN_FAILED. @cpu is in the same pod of the CPU being hot[un]plugged. + * + * + * If pod affinity can't be adjusted due to memory allocation failure, it falls + * back to @wq->dfl_pwq which may not be optimal but is always correct. + * + * Note that when the last allowed CPU of a pod goes offline for a workqueue + * with a cpumask spanning multiple pods, the workers which were already + * executing the work items for the workqueue will lose their CPU affinity and + * may execute on any CPU. This is similar to how per-cpu workqueues behave on + * CPU_DOWN. If a workqueue user wants strict affinity, it's the user's + * responsibility to flush the work item from CPU_DOWN_PREPARE. + */ +static void unbound_wq_update_pwq(struct workqueue_struct *wq, int cpu) +{ struct pool_workqueue *old_pwq = NULL, *pwq; struct workqueue_attrs *target_attrs; - cpumask_t *cpumask; lockdep_assert_held(&wq_pool_mutex); - if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND)) + if (!(wq->flags & WQ_UNBOUND) || wq->unbound_attrs->ordered) return; /* @@ -3991,58 +5464,36 @@ static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu, * Let's use a preallocated one. The following buf is protected by * CPU hotplug exclusion. */ - target_attrs = wq_update_unbound_numa_attrs_buf; - cpumask = target_attrs->cpumask; - - mutex_lock(&wq->mutex); - if (wq->unbound_attrs->no_numa) - goto out_unlock; + target_attrs = unbound_wq_update_pwq_attrs_buf; copy_workqueue_attrs(target_attrs, wq->unbound_attrs); - pwq = unbound_pwq_by_node(wq, node); - - /* - * Let's determine what needs to be done. If the target cpumask is - * different from wq's, we need to compare it to @pwq's and create - * a new one if they don't match. If the target cpumask equals - * wq's, the default pwq should be used. If @pwq is already the - * default one, nothing to do; otherwise, install the default one. - */ - if (wq_calc_node_cpumask(wq->unbound_attrs, node, cpu_off, cpumask)) { - if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask)) - goto out_unlock; - } else { - if (pwq == wq->dfl_pwq) - goto out_unlock; - else - goto use_dfl_pwq; - } + wqattrs_actualize_cpumask(target_attrs, wq_unbound_cpumask); - mutex_unlock(&wq->mutex); + /* nothing to do if the target cpumask matches the current pwq */ + wq_calc_pod_cpumask(target_attrs, cpu); + if (wqattrs_equal(target_attrs, unbound_pwq(wq, cpu)->pool->attrs)) + return; /* create a new pwq */ pwq = alloc_unbound_pwq(wq, target_attrs); if (!pwq) { - pr_warning("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n", - wq->name); - goto out_unlock; + pr_warn("workqueue: allocation failed while updating CPU pod affinity of \"%s\"\n", + wq->name); + goto use_dfl_pwq; } - /* - * Install the new pwq. As this function is called only from CPU - * hotplug callbacks and applying a new attrs is wrapped with - * get/put_online_cpus(), @wq->unbound_attrs couldn't have changed - * inbetween. - */ + /* Install the new pwq. */ mutex_lock(&wq->mutex); - old_pwq = numa_pwq_tbl_install(wq, node, pwq); + old_pwq = install_unbound_pwq(wq, cpu, pwq); goto out_unlock; use_dfl_pwq: - spin_lock_irq(&wq->dfl_pwq->pool->lock); - get_pwq(wq->dfl_pwq); - spin_unlock_irq(&wq->dfl_pwq->pool->lock); - old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq); + mutex_lock(&wq->mutex); + pwq = unbound_pwq(wq, -1); + raw_spin_lock_irq(&pwq->pool->lock); + get_pwq(pwq); + raw_spin_unlock_irq(&pwq->pool->lock); + old_pwq = install_unbound_pwq(wq, cpu, pwq); out_unlock: mutex_unlock(&wq->mutex); put_pwq_unlocked(old_pwq); @@ -4051,53 +5502,207 @@ out_unlock: static int alloc_and_link_pwqs(struct workqueue_struct *wq) { bool highpri = wq->flags & WQ_HIGHPRI; - int cpu; + int cpu, ret; + + lockdep_assert_held(&wq_pool_mutex); + + wq->cpu_pwq = alloc_percpu(struct pool_workqueue *); + if (!wq->cpu_pwq) + goto enomem; if (!(wq->flags & WQ_UNBOUND)) { - wq->cpu_pwqs = alloc_percpu(struct pool_workqueue); - if (!wq->cpu_pwqs) - return -ENOMEM; + struct worker_pool __percpu *pools; + + if (wq->flags & WQ_BH) + pools = bh_worker_pools; + else + pools = cpu_worker_pools; for_each_possible_cpu(cpu) { - struct pool_workqueue *pwq = - per_cpu_ptr(wq->cpu_pwqs, cpu); - struct worker_pool *cpu_pools = - per_cpu(cpu_worker_pools, cpu); + struct pool_workqueue **pwq_p; + struct worker_pool *pool; + + pool = &(per_cpu_ptr(pools, cpu)[highpri]); + pwq_p = per_cpu_ptr(wq->cpu_pwq, cpu); - init_pwq(pwq, wq, &cpu_pools[highpri]); + *pwq_p = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, + pool->node); + if (!*pwq_p) + goto enomem; + + init_pwq(*pwq_p, wq, pool); mutex_lock(&wq->mutex); - link_pwq(pwq); + link_pwq(*pwq_p); mutex_unlock(&wq->mutex); } return 0; + } + + if (wq->flags & __WQ_ORDERED) { + struct pool_workqueue *dfl_pwq; + + ret = apply_workqueue_attrs_locked(wq, ordered_wq_attrs[highpri]); + /* there should only be single pwq for ordering guarantee */ + dfl_pwq = rcu_access_pointer(wq->dfl_pwq); + WARN(!ret && (wq->pwqs.next != &dfl_pwq->pwqs_node || + wq->pwqs.prev != &dfl_pwq->pwqs_node), + "ordering guarantee broken for workqueue %s\n", wq->name); } else { - return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]); + ret = apply_workqueue_attrs_locked(wq, unbound_std_wq_attrs[highpri]); } + + return ret; + +enomem: + if (wq->cpu_pwq) { + for_each_possible_cpu(cpu) { + struct pool_workqueue *pwq = *per_cpu_ptr(wq->cpu_pwq, cpu); + + if (pwq) + kmem_cache_free(pwq_cache, pwq); + } + free_percpu(wq->cpu_pwq); + wq->cpu_pwq = NULL; + } + return -ENOMEM; } static int wq_clamp_max_active(int max_active, unsigned int flags, const char *name) { - int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; - - if (max_active < 1 || max_active > lim) + if (max_active < 1 || max_active > WQ_MAX_ACTIVE) pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", - max_active, name, 1, lim); + max_active, name, 1, WQ_MAX_ACTIVE); - return clamp_val(max_active, 1, lim); + return clamp_val(max_active, 1, WQ_MAX_ACTIVE); } -struct workqueue_struct *__alloc_workqueue_key(const char *fmt, - unsigned int flags, - int max_active, - struct lock_class_key *key, - const char *lock_name, ...) +/* + * Workqueues which may be used during memory reclaim should have a rescuer + * to guarantee forward progress. + */ +static int init_rescuer(struct workqueue_struct *wq) +{ + struct worker *rescuer; + char id_buf[WORKER_ID_LEN]; + int ret; + + lockdep_assert_held(&wq_pool_mutex); + + if (!(wq->flags & WQ_MEM_RECLAIM)) + return 0; + + rescuer = alloc_worker(NUMA_NO_NODE); + if (!rescuer) { + pr_err("workqueue: Failed to allocate a rescuer for wq \"%s\"\n", + wq->name); + return -ENOMEM; + } + + rescuer->rescue_wq = wq; + format_worker_id(id_buf, sizeof(id_buf), rescuer, NULL); + + rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", id_buf); + if (IS_ERR(rescuer->task)) { + ret = PTR_ERR(rescuer->task); + pr_err("workqueue: Failed to create a rescuer kthread for wq \"%s\": %pe", + wq->name, ERR_PTR(ret)); + kfree(rescuer); + return ret; + } + + wq->rescuer = rescuer; + + /* initial cpumask is consistent with the detached rescuer and unbind_worker() */ + if (cpumask_intersects(wq_unbound_cpumask, cpu_active_mask)) + kthread_bind_mask(rescuer->task, wq_unbound_cpumask); + else + kthread_bind_mask(rescuer->task, cpu_possible_mask); + + wake_up_process(rescuer->task); + + return 0; +} + +/** + * wq_adjust_max_active - update a wq's max_active to the current setting + * @wq: target workqueue + * + * If @wq isn't freezing, set @wq->max_active to the saved_max_active and + * activate inactive work items accordingly. If @wq is freezing, clear + * @wq->max_active to zero. + */ +static void wq_adjust_max_active(struct workqueue_struct *wq) +{ + bool activated; + int new_max, new_min; + + lockdep_assert_held(&wq->mutex); + + if ((wq->flags & WQ_FREEZABLE) && workqueue_freezing) { + new_max = 0; + new_min = 0; + } else { + new_max = wq->saved_max_active; + new_min = wq->saved_min_active; + } + + if (wq->max_active == new_max && wq->min_active == new_min) + return; + + /* + * Update @wq->max/min_active and then kick inactive work items if more + * active work items are allowed. This doesn't break work item ordering + * because new work items are always queued behind existing inactive + * work items if there are any. + */ + WRITE_ONCE(wq->max_active, new_max); + WRITE_ONCE(wq->min_active, new_min); + + if (wq->flags & WQ_UNBOUND) + wq_update_node_max_active(wq, -1); + + if (new_max == 0) + return; + + /* + * Round-robin through pwq's activating the first inactive work item + * until max_active is filled. + */ + do { + struct pool_workqueue *pwq; + + activated = false; + for_each_pwq(pwq, wq) { + unsigned long irq_flags; + + /* can be called during early boot w/ irq disabled */ + raw_spin_lock_irqsave(&pwq->pool->lock, irq_flags); + if (pwq_activate_first_inactive(pwq, true)) { + activated = true; + kick_pool(pwq->pool); + } + raw_spin_unlock_irqrestore(&pwq->pool->lock, irq_flags); + } + } while (activated); +} + +__printf(1, 0) +static struct workqueue_struct *__alloc_workqueue(const char *fmt, + unsigned int flags, + int max_active, va_list args) { - size_t tbl_size = 0; - va_list args; struct workqueue_struct *wq; - struct pool_workqueue *pwq; + size_t wq_size; + int name_len; + + if (flags & WQ_BH) { + if (WARN_ON_ONCE(flags & ~__WQ_BH_ALLOWS)) + return NULL; + if (WARN_ON_ONCE(max_active)) + return NULL; + } /* see the comment above the definition of WQ_POWER_EFFICIENT */ if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient) @@ -4105,28 +5710,43 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt, /* allocate wq and format name */ if (flags & WQ_UNBOUND) - tbl_size = wq_numa_tbl_len * sizeof(wq->numa_pwq_tbl[0]); + wq_size = struct_size(wq, node_nr_active, nr_node_ids + 1); + else + wq_size = sizeof(*wq); - wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL); + wq = kzalloc_noprof(wq_size, GFP_KERNEL); if (!wq) return NULL; if (flags & WQ_UNBOUND) { - wq->unbound_attrs = alloc_workqueue_attrs(GFP_KERNEL); + wq->unbound_attrs = alloc_workqueue_attrs_noprof(); if (!wq->unbound_attrs) goto err_free_wq; } - va_start(args, lock_name); - vsnprintf(wq->name, sizeof(wq->name), fmt, args); - va_end(args); + name_len = vsnprintf(wq->name, sizeof(wq->name), fmt, args); + + if (name_len >= WQ_NAME_LEN) + pr_warn_once("workqueue: name exceeds WQ_NAME_LEN. Truncating to: %s\n", + wq->name); - max_active = max_active ?: WQ_DFL_ACTIVE; - max_active = wq_clamp_max_active(max_active, flags, wq->name); + if (flags & WQ_BH) { + /* + * BH workqueues always share a single execution context per CPU + * and don't impose any max_active limit. + */ + max_active = INT_MAX; + } else { + max_active = max_active ?: WQ_DFL_ACTIVE; + max_active = wq_clamp_max_active(max_active, flags, wq->name); + } /* init wq */ wq->flags = flags; - wq->saved_max_active = max_active; + wq->max_active = max_active; + wq->min_active = min(max_active, WQ_DFL_MIN_ACTIVE); + wq->saved_max_active = wq->max_active; + wq->saved_min_active = wq->min_active; mutex_init(&wq->mutex); atomic_set(&wq->nr_pwqs_to_flush, 0); INIT_LIST_HEAD(&wq->pwqs); @@ -4134,99 +5754,181 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt, INIT_LIST_HEAD(&wq->flusher_overflow); INIT_LIST_HEAD(&wq->maydays); - lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); INIT_LIST_HEAD(&wq->list); - if (alloc_and_link_pwqs(wq) < 0) - goto err_free_wq; - - /* - * Workqueues which may be used during memory reclaim should - * have a rescuer to guarantee forward progress. - */ - if (flags & WQ_MEM_RECLAIM) { - struct worker *rescuer; - - rescuer = alloc_worker(); - if (!rescuer) - goto err_destroy; - - rescuer->rescue_wq = wq; - rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", - wq->name); - if (IS_ERR(rescuer->task)) { - kfree(rescuer); - goto err_destroy; - } - - wq->rescuer = rescuer; - rescuer->task->flags |= PF_NO_SETAFFINITY; - wake_up_process(rescuer->task); + if (flags & WQ_UNBOUND) { + if (alloc_node_nr_active(wq->node_nr_active) < 0) + goto err_free_wq; } - if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq)) - goto err_destroy; - /* - * wq_pool_mutex protects global freeze state and workqueues list. - * Grab it, adjust max_active and add the new @wq to workqueues - * list. + * wq_pool_mutex protects the workqueues list, allocations of PWQs, + * and the global freeze state. */ - mutex_lock(&wq_pool_mutex); + apply_wqattrs_lock(); + + if (alloc_and_link_pwqs(wq) < 0) + goto err_unlock_free_node_nr_active; mutex_lock(&wq->mutex); - for_each_pwq(pwq, wq) - pwq_adjust_max_active(pwq); + wq_adjust_max_active(wq); mutex_unlock(&wq->mutex); - list_add(&wq->list, &workqueues); + list_add_tail_rcu(&wq->list, &workqueues); - mutex_unlock(&wq_pool_mutex); + if (wq_online && init_rescuer(wq) < 0) + goto err_unlock_destroy; + + apply_wqattrs_unlock(); + + if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq)) + goto err_destroy; return wq; +err_unlock_free_node_nr_active: + apply_wqattrs_unlock(); + /* + * Failed alloc_and_link_pwqs() may leave pending pwq->release_work, + * flushing the pwq_release_worker ensures that the pwq_release_workfn() + * completes before calling kfree(wq). + */ + if (wq->flags & WQ_UNBOUND) { + kthread_flush_worker(pwq_release_worker); + free_node_nr_active(wq->node_nr_active); + } err_free_wq: free_workqueue_attrs(wq->unbound_attrs); kfree(wq); return NULL; +err_unlock_destroy: + apply_wqattrs_unlock(); err_destroy: destroy_workqueue(wq); return NULL; } -EXPORT_SYMBOL_GPL(__alloc_workqueue_key); + +__printf(1, 4) +struct workqueue_struct *alloc_workqueue_noprof(const char *fmt, + unsigned int flags, + int max_active, ...) +{ + struct workqueue_struct *wq; + va_list args; + + va_start(args, max_active); + wq = __alloc_workqueue(fmt, flags, max_active, args); + va_end(args); + if (!wq) + return NULL; + + wq_init_lockdep(wq); + + return wq; +} +EXPORT_SYMBOL_GPL(alloc_workqueue_noprof); + +#ifdef CONFIG_LOCKDEP +__printf(1, 5) +struct workqueue_struct * +alloc_workqueue_lockdep_map(const char *fmt, unsigned int flags, + int max_active, struct lockdep_map *lockdep_map, ...) +{ + struct workqueue_struct *wq; + va_list args; + + va_start(args, lockdep_map); + wq = __alloc_workqueue(fmt, flags, max_active, args); + va_end(args); + if (!wq) + return NULL; + + wq->lockdep_map = lockdep_map; + + return wq; +} +EXPORT_SYMBOL_GPL(alloc_workqueue_lockdep_map); +#endif + +static bool pwq_busy(struct pool_workqueue *pwq) +{ + int i; + + for (i = 0; i < WORK_NR_COLORS; i++) + if (pwq->nr_in_flight[i]) + return true; + + if ((pwq != rcu_access_pointer(pwq->wq->dfl_pwq)) && (pwq->refcnt > 1)) + return true; + if (!pwq_is_empty(pwq)) + return true; + + return false; +} /** * destroy_workqueue - safely terminate a workqueue * @wq: target workqueue * * Safely destroy a workqueue. All work currently pending will be done first. + * + * This function does NOT guarantee that non-pending work that has been + * submitted with queue_delayed_work() and similar functions will be done + * before destroying the workqueue. The fundamental problem is that, currently, + * the workqueue has no way of accessing non-pending delayed_work. delayed_work + * is only linked on the timer-side. All delayed_work must, therefore, be + * canceled before calling this function. + * + * TODO: It would be better if the problem described above wouldn't exist and + * destroy_workqueue() would cleanly cancel all pending and non-pending + * delayed_work. */ void destroy_workqueue(struct workqueue_struct *wq) { struct pool_workqueue *pwq; - int node; + int cpu; + + /* + * Remove it from sysfs first so that sanity check failure doesn't + * lead to sysfs name conflicts. + */ + workqueue_sysfs_unregister(wq); + + /* mark the workqueue destruction is in progress */ + mutex_lock(&wq->mutex); + wq->flags |= __WQ_DESTROYING; + mutex_unlock(&wq->mutex); /* drain it before proceeding with destruction */ drain_workqueue(wq); - /* sanity checks */ + /* kill rescuer, if sanity checks fail, leave it w/o rescuer */ + if (wq->rescuer) { + /* rescuer will empty maydays list before exiting */ + kthread_stop(wq->rescuer->task); + kfree(wq->rescuer); + wq->rescuer = NULL; + } + + /* + * Sanity checks - grab all the locks so that we wait for all + * in-flight operations which may do put_pwq(). + */ + mutex_lock(&wq_pool_mutex); mutex_lock(&wq->mutex); for_each_pwq(pwq, wq) { - int i; - - for (i = 0; i < WORK_NR_COLORS; i++) { - if (WARN_ON(pwq->nr_in_flight[i])) { - mutex_unlock(&wq->mutex); - return; - } - } - - if (WARN_ON((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) || - WARN_ON(pwq->nr_active) || - WARN_ON(!list_empty(&pwq->delayed_works))) { + raw_spin_lock_irq(&pwq->pool->lock); + if (WARN_ON(pwq_busy(pwq))) { + pr_warn("%s: %s has the following busy pwq\n", + __func__, wq->name); + show_pwq(pwq); + raw_spin_unlock_irq(&pwq->pool->lock); mutex_unlock(&wq->mutex); + mutex_unlock(&wq_pool_mutex); + show_one_workqueue(wq); return; } + raw_spin_unlock_irq(&pwq->pool->lock); } mutex_unlock(&wq->mutex); @@ -4234,45 +5936,25 @@ void destroy_workqueue(struct workqueue_struct *wq) * wq list is used to freeze wq, remove from list after * flushing is complete in case freeze races us. */ - mutex_lock(&wq_pool_mutex); - list_del_init(&wq->list); + list_del_rcu(&wq->list); mutex_unlock(&wq_pool_mutex); - workqueue_sysfs_unregister(wq); + /* + * We're the sole accessor of @wq. Directly access cpu_pwq and dfl_pwq + * to put the base refs. @wq will be auto-destroyed from the last + * pwq_put. RCU read lock prevents @wq from going away from under us. + */ + rcu_read_lock(); - if (wq->rescuer) { - kthread_stop(wq->rescuer->task); - kfree(wq->rescuer); - wq->rescuer = NULL; + for_each_possible_cpu(cpu) { + put_pwq_unlocked(unbound_pwq(wq, cpu)); + RCU_INIT_POINTER(*unbound_pwq_slot(wq, cpu), NULL); } - if (!(wq->flags & WQ_UNBOUND)) { - /* - * The base ref is never dropped on per-cpu pwqs. Directly - * free the pwqs and wq. - */ - free_percpu(wq->cpu_pwqs); - kfree(wq); - } else { - /* - * We're the sole accessor of @wq at this point. Directly - * access numa_pwq_tbl[] and dfl_pwq to put the base refs. - * @wq will be freed when the last pwq is released. - */ - for_each_node(node) { - pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); - RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL); - put_pwq_unlocked(pwq); - } + put_pwq_unlocked(unbound_pwq(wq, -1)); + RCU_INIT_POINTER(*unbound_pwq_slot(wq, -1), NULL); - /* - * Put dfl_pwq. @wq may be freed any time after dfl_pwq is - * put. Don't access it afterwards. - */ - pwq = wq->dfl_pwq; - wq->dfl_pwq = NULL; - put_pwq_unlocked(pwq); - } + rcu_read_unlock(); } EXPORT_SYMBOL_GPL(destroy_workqueue); @@ -4281,15 +5963,17 @@ EXPORT_SYMBOL_GPL(destroy_workqueue); * @wq: target workqueue * @max_active: new max_active value. * - * Set max_active of @wq to @max_active. + * Set max_active of @wq to @max_active. See the alloc_workqueue() function + * comment. * * CONTEXT: * Don't call from IRQ context. */ void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) { - struct pool_workqueue *pwq; - + /* max_active doesn't mean anything for BH workqueues */ + if (WARN_ON(wq->flags & WQ_BH)) + return; /* disallow meddling with max_active for ordered workqueues */ if (WARN_ON(wq->flags & __WQ_ORDERED)) return; @@ -4299,19 +5983,65 @@ void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) mutex_lock(&wq->mutex); wq->saved_max_active = max_active; + if (wq->flags & WQ_UNBOUND) + wq->saved_min_active = min(wq->saved_min_active, max_active); - for_each_pwq(pwq, wq) - pwq_adjust_max_active(pwq); + wq_adjust_max_active(wq); mutex_unlock(&wq->mutex); } EXPORT_SYMBOL_GPL(workqueue_set_max_active); /** + * workqueue_set_min_active - adjust min_active of an unbound workqueue + * @wq: target unbound workqueue + * @min_active: new min_active value + * + * Set min_active of an unbound workqueue. Unlike other types of workqueues, an + * unbound workqueue is not guaranteed to be able to process max_active + * interdependent work items. Instead, an unbound workqueue is guaranteed to be + * able to process min_active number of interdependent work items which is + * %WQ_DFL_MIN_ACTIVE by default. + * + * Use this function to adjust the min_active value between 0 and the current + * max_active. + */ +void workqueue_set_min_active(struct workqueue_struct *wq, int min_active) +{ + /* min_active is only meaningful for non-ordered unbound workqueues */ + if (WARN_ON((wq->flags & (WQ_BH | WQ_UNBOUND | __WQ_ORDERED)) != + WQ_UNBOUND)) + return; + + mutex_lock(&wq->mutex); + wq->saved_min_active = clamp(min_active, 0, wq->saved_max_active); + wq_adjust_max_active(wq); + mutex_unlock(&wq->mutex); +} + +/** + * current_work - retrieve %current task's work struct + * + * Determine if %current task is a workqueue worker and what it's working on. + * Useful to find out the context that the %current task is running in. + * + * Return: work struct if %current task is a workqueue worker, %NULL otherwise. + */ +struct work_struct *current_work(void) +{ + struct worker *worker = current_wq_worker(); + + return worker ? worker->current_work : NULL; +} +EXPORT_SYMBOL(current_work); + +/** * current_is_workqueue_rescuer - is %current workqueue rescuer? * * Determine whether %current is a workqueue rescuer. Can be used from * work functions to determine whether it's being run off the rescuer task. + * + * Return: %true if %current is a workqueue rescuer. %false otherwise. */ bool current_is_workqueue_rescuer(void) { @@ -4330,12 +6060,13 @@ bool current_is_workqueue_rescuer(void) * unreliable and only useful as advisory hints or for debugging. * * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU. - * Note that both per-cpu and unbound workqueues may be associated with - * multiple pool_workqueues which have separate congested states. A - * workqueue being congested on one CPU doesn't mean the workqueue is also - * contested on other CPUs / NUMA nodes. * - * RETURNS: + * With the exception of ordered workqueues, all workqueues have per-cpu + * pool_workqueues, each with its own congested state. A workqueue being + * congested on one CPU doesn't mean that the workqueue is contested on any + * other CPUs. + * + * Return: * %true if congested, %false otherwise. */ bool workqueue_congested(int cpu, struct workqueue_struct *wq) @@ -4343,18 +6074,15 @@ bool workqueue_congested(int cpu, struct workqueue_struct *wq) struct pool_workqueue *pwq; bool ret; - rcu_read_lock_sched(); + preempt_disable(); if (cpu == WORK_CPU_UNBOUND) cpu = smp_processor_id(); - if (!(wq->flags & WQ_UNBOUND)) - pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); - else - pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); + pwq = *per_cpu_ptr(wq->cpu_pwq, cpu); + ret = !list_empty(&pwq->inactive_works); - ret = !list_empty(&pwq->delayed_works); - rcu_read_unlock_sched(); + preempt_enable(); return ret; } @@ -4368,27 +6096,27 @@ EXPORT_SYMBOL_GPL(workqueue_congested); * synchronization around this function and the test result is * unreliable and only useful as advisory hints or for debugging. * - * RETURNS: + * Return: * OR'd bitmask of WORK_BUSY_* bits. */ unsigned int work_busy(struct work_struct *work) { struct worker_pool *pool; - unsigned long flags; + unsigned long irq_flags; unsigned int ret = 0; if (work_pending(work)) ret |= WORK_BUSY_PENDING; - local_irq_save(flags); + rcu_read_lock(); pool = get_work_pool(work); if (pool) { - spin_lock(&pool->lock); + raw_spin_lock_irqsave(&pool->lock, irq_flags); if (find_worker_executing_work(pool, work)) ret |= WORK_BUSY_RUNNING; - spin_unlock(&pool->lock); + raw_spin_unlock_irqrestore(&pool->lock, irq_flags); } - local_irq_restore(flags); + rcu_read_unlock(); return ret; } @@ -4413,9 +6141,9 @@ void set_worker_desc(const char *fmt, ...) va_start(args, fmt); vsnprintf(worker->desc, sizeof(worker->desc), fmt, args); va_end(args); - worker->desc_valid = true; } } +EXPORT_SYMBOL_GPL(set_worker_desc); /** * print_worker_info - print out worker information and description @@ -4437,7 +6165,6 @@ void print_worker_info(const char *log_lvl, struct task_struct *task) char desc[WORKER_DESC_LEN] = { }; struct pool_workqueue *pwq = NULL; struct workqueue_struct *wq = NULL; - bool desc_valid = false; struct worker *worker; if (!(task->flags & PF_WQ_WORKER)) @@ -4447,30 +6174,349 @@ void print_worker_info(const char *log_lvl, struct task_struct *task) * This function is called without any synchronization and @task * could be in any state. Be careful with dereferences. */ - worker = probe_kthread_data(task); + worker = kthread_probe_data(task); /* - * Carefully copy the associated workqueue's workfn and name. Keep - * the original last '\0' in case the original contains garbage. + * Carefully copy the associated workqueue's workfn, name and desc. + * Keep the original last '\0' in case the original is garbage. */ - probe_kernel_read(&fn, &worker->current_func, sizeof(fn)); - probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq)); - probe_kernel_read(&wq, &pwq->wq, sizeof(wq)); - probe_kernel_read(name, wq->name, sizeof(name) - 1); - - /* copy worker description */ - probe_kernel_read(&desc_valid, &worker->desc_valid, sizeof(desc_valid)); - if (desc_valid) - probe_kernel_read(desc, worker->desc, sizeof(desc) - 1); + copy_from_kernel_nofault(&fn, &worker->current_func, sizeof(fn)); + copy_from_kernel_nofault(&pwq, &worker->current_pwq, sizeof(pwq)); + copy_from_kernel_nofault(&wq, &pwq->wq, sizeof(wq)); + copy_from_kernel_nofault(name, wq->name, sizeof(name) - 1); + copy_from_kernel_nofault(desc, worker->desc, sizeof(desc) - 1); if (fn || name[0] || desc[0]) { - printk("%sWorkqueue: %s %pf", log_lvl, name, fn); - if (desc[0]) + printk("%sWorkqueue: %s %ps", log_lvl, name, fn); + if (strcmp(name, desc)) pr_cont(" (%s)", desc); pr_cont("\n"); } } +static void pr_cont_pool_info(struct worker_pool *pool) +{ + pr_cont(" cpus=%*pbl", nr_cpumask_bits, pool->attrs->cpumask); + if (pool->node != NUMA_NO_NODE) + pr_cont(" node=%d", pool->node); + pr_cont(" flags=0x%x", pool->flags); + if (pool->flags & POOL_BH) + pr_cont(" bh%s", + pool->attrs->nice == HIGHPRI_NICE_LEVEL ? "-hi" : ""); + else + pr_cont(" nice=%d", pool->attrs->nice); +} + +static void pr_cont_worker_id(struct worker *worker) +{ + struct worker_pool *pool = worker->pool; + + if (pool->flags & WQ_BH) + pr_cont("bh%s", + pool->attrs->nice == HIGHPRI_NICE_LEVEL ? "-hi" : ""); + else + pr_cont("%d%s", task_pid_nr(worker->task), + worker->rescue_wq ? "(RESCUER)" : ""); +} + +struct pr_cont_work_struct { + bool comma; + work_func_t func; + long ctr; +}; + +static void pr_cont_work_flush(bool comma, work_func_t func, struct pr_cont_work_struct *pcwsp) +{ + if (!pcwsp->ctr) + goto out_record; + if (func == pcwsp->func) { + pcwsp->ctr++; + return; + } + if (pcwsp->ctr == 1) + pr_cont("%s %ps", pcwsp->comma ? "," : "", pcwsp->func); + else + pr_cont("%s %ld*%ps", pcwsp->comma ? "," : "", pcwsp->ctr, pcwsp->func); + pcwsp->ctr = 0; +out_record: + if ((long)func == -1L) + return; + pcwsp->comma = comma; + pcwsp->func = func; + pcwsp->ctr = 1; +} + +static void pr_cont_work(bool comma, struct work_struct *work, struct pr_cont_work_struct *pcwsp) +{ + if (work->func == wq_barrier_func) { + struct wq_barrier *barr; + + barr = container_of(work, struct wq_barrier, work); + + pr_cont_work_flush(comma, (work_func_t)-1, pcwsp); + pr_cont("%s BAR(%d)", comma ? "," : "", + task_pid_nr(barr->task)); + } else { + if (!comma) + pr_cont_work_flush(comma, (work_func_t)-1, pcwsp); + pr_cont_work_flush(comma, work->func, pcwsp); + } +} + +static void show_pwq(struct pool_workqueue *pwq) +{ + struct pr_cont_work_struct pcws = { .ctr = 0, }; + struct worker_pool *pool = pwq->pool; + struct work_struct *work; + struct worker *worker; + bool has_in_flight = false, has_pending = false; + int bkt; + + pr_info(" pwq %d:", pool->id); + pr_cont_pool_info(pool); + + pr_cont(" active=%d refcnt=%d%s\n", + pwq->nr_active, pwq->refcnt, + !list_empty(&pwq->mayday_node) ? " MAYDAY" : ""); + + hash_for_each(pool->busy_hash, bkt, worker, hentry) { + if (worker->current_pwq == pwq) { + has_in_flight = true; + break; + } + } + if (has_in_flight) { + bool comma = false; + + pr_info(" in-flight:"); + hash_for_each(pool->busy_hash, bkt, worker, hentry) { + if (worker->current_pwq != pwq) + continue; + + pr_cont(" %s", comma ? "," : ""); + pr_cont_worker_id(worker); + pr_cont(":%ps", worker->current_func); + list_for_each_entry(work, &worker->scheduled, entry) + pr_cont_work(false, work, &pcws); + pr_cont_work_flush(comma, (work_func_t)-1L, &pcws); + comma = true; + } + pr_cont("\n"); + } + + list_for_each_entry(work, &pool->worklist, entry) { + if (get_work_pwq(work) == pwq) { + has_pending = true; + break; + } + } + if (has_pending) { + bool comma = false; + + pr_info(" pending:"); + list_for_each_entry(work, &pool->worklist, entry) { + if (get_work_pwq(work) != pwq) + continue; + + pr_cont_work(comma, work, &pcws); + comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); + } + pr_cont_work_flush(comma, (work_func_t)-1L, &pcws); + pr_cont("\n"); + } + + if (!list_empty(&pwq->inactive_works)) { + bool comma = false; + + pr_info(" inactive:"); + list_for_each_entry(work, &pwq->inactive_works, entry) { + pr_cont_work(comma, work, &pcws); + comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); + } + pr_cont_work_flush(comma, (work_func_t)-1L, &pcws); + pr_cont("\n"); + } +} + +/** + * show_one_workqueue - dump state of specified workqueue + * @wq: workqueue whose state will be printed + */ +void show_one_workqueue(struct workqueue_struct *wq) +{ + struct pool_workqueue *pwq; + bool idle = true; + unsigned long irq_flags; + + for_each_pwq(pwq, wq) { + if (!pwq_is_empty(pwq)) { + idle = false; + break; + } + } + if (idle) /* Nothing to print for idle workqueue */ + return; + + pr_info("workqueue %s: flags=0x%x\n", wq->name, wq->flags); + + for_each_pwq(pwq, wq) { + raw_spin_lock_irqsave(&pwq->pool->lock, irq_flags); + if (!pwq_is_empty(pwq)) { + /* + * Defer printing to avoid deadlocks in console + * drivers that queue work while holding locks + * also taken in their write paths. + */ + printk_deferred_enter(); + show_pwq(pwq); + printk_deferred_exit(); + } + raw_spin_unlock_irqrestore(&pwq->pool->lock, irq_flags); + /* + * We could be printing a lot from atomic context, e.g. + * sysrq-t -> show_all_workqueues(). Avoid triggering + * hard lockup. + */ + touch_nmi_watchdog(); + } + +} + +/** + * show_one_worker_pool - dump state of specified worker pool + * @pool: worker pool whose state will be printed + */ +static void show_one_worker_pool(struct worker_pool *pool) +{ + struct worker *worker; + bool first = true; + unsigned long irq_flags; + unsigned long hung = 0; + + raw_spin_lock_irqsave(&pool->lock, irq_flags); + if (pool->nr_workers == pool->nr_idle) + goto next_pool; + + /* How long the first pending work is waiting for a worker. */ + if (!list_empty(&pool->worklist)) + hung = jiffies_to_msecs(jiffies - pool->watchdog_ts) / 1000; + + /* + * Defer printing to avoid deadlocks in console drivers that + * queue work while holding locks also taken in their write + * paths. + */ + printk_deferred_enter(); + pr_info("pool %d:", pool->id); + pr_cont_pool_info(pool); + pr_cont(" hung=%lus workers=%d", hung, pool->nr_workers); + if (pool->manager) + pr_cont(" manager: %d", + task_pid_nr(pool->manager->task)); + list_for_each_entry(worker, &pool->idle_list, entry) { + pr_cont(" %s", first ? "idle: " : ""); + pr_cont_worker_id(worker); + first = false; + } + pr_cont("\n"); + printk_deferred_exit(); +next_pool: + raw_spin_unlock_irqrestore(&pool->lock, irq_flags); + /* + * We could be printing a lot from atomic context, e.g. + * sysrq-t -> show_all_workqueues(). Avoid triggering + * hard lockup. + */ + touch_nmi_watchdog(); + +} + +/** + * show_all_workqueues - dump workqueue state + * + * Called from a sysrq handler and prints out all busy workqueues and pools. + */ +void show_all_workqueues(void) +{ + struct workqueue_struct *wq; + struct worker_pool *pool; + int pi; + + rcu_read_lock(); + + pr_info("Showing busy workqueues and worker pools:\n"); + + list_for_each_entry_rcu(wq, &workqueues, list) + show_one_workqueue(wq); + + for_each_pool(pool, pi) + show_one_worker_pool(pool); + + rcu_read_unlock(); +} + +/** + * show_freezable_workqueues - dump freezable workqueue state + * + * Called from try_to_freeze_tasks() and prints out all freezable workqueues + * still busy. + */ +void show_freezable_workqueues(void) +{ + struct workqueue_struct *wq; + + rcu_read_lock(); + + pr_info("Showing freezable workqueues that are still busy:\n"); + + list_for_each_entry_rcu(wq, &workqueues, list) { + if (!(wq->flags & WQ_FREEZABLE)) + continue; + show_one_workqueue(wq); + } + + rcu_read_unlock(); +} + +/* used to show worker information through /proc/PID/{comm,stat,status} */ +void wq_worker_comm(char *buf, size_t size, struct task_struct *task) +{ + /* stabilize PF_WQ_WORKER and worker pool association */ + mutex_lock(&wq_pool_attach_mutex); + + if (task->flags & PF_WQ_WORKER) { + struct worker *worker = kthread_data(task); + struct worker_pool *pool = worker->pool; + int off; + + off = format_worker_id(buf, size, worker, pool); + + if (pool) { + raw_spin_lock_irq(&pool->lock); + /* + * ->desc tracks information (wq name or + * set_worker_desc()) for the latest execution. If + * current, prepend '+', otherwise '-'. + */ + if (worker->desc[0] != '\0') { + if (worker->current_work) + scnprintf(buf + off, size - off, "+%s", + worker->desc); + else + scnprintf(buf + off, size - off, "-%s", + worker->desc); + } + raw_spin_unlock_irq(&pool->lock); + } + } else { + strscpy(buf, task->comm, size); + } + + mutex_unlock(&wq_pool_attach_mutex); +} + +#ifdef CONFIG_SMP + /* * CPU hotplug. * @@ -4486,60 +6532,51 @@ void print_worker_info(const char *log_lvl, struct task_struct *task) * cpu comes back online. */ -static void wq_unbind_fn(struct work_struct *work) +static void unbind_workers(int cpu) { - int cpu = smp_processor_id(); struct worker_pool *pool; struct worker *worker; - int wi; for_each_cpu_worker_pool(pool, cpu) { - WARN_ON_ONCE(cpu != smp_processor_id()); - - mutex_lock(&pool->manager_mutex); - spin_lock_irq(&pool->lock); + mutex_lock(&wq_pool_attach_mutex); + raw_spin_lock_irq(&pool->lock); /* - * We've blocked all manager operations. Make all workers + * We've blocked all attach/detach operations. Make all workers * unbound and set DISASSOCIATED. Before this, all workers - * except for the ones which are still executing works from - * before the last CPU down must be on the cpu. After - * this, they may become diasporas. + * must be on the cpu. After this, they may become diasporas. + * And the preemption disabled section in their sched callbacks + * are guaranteed to see WORKER_UNBOUND since the code here + * is on the same cpu. */ - for_each_pool_worker(worker, wi, pool) + for_each_pool_worker(worker, pool) worker->flags |= WORKER_UNBOUND; pool->flags |= POOL_DISASSOCIATED; - spin_unlock_irq(&pool->lock); - mutex_unlock(&pool->manager_mutex); - /* - * Call schedule() so that we cross rq->lock and thus can - * guarantee sched callbacks see the %WORKER_UNBOUND flag. - * This is necessary as scheduler callbacks may be invoked - * from other cpus. - */ - schedule(); - - /* - * Sched callbacks are disabled now. Zap nr_running. - * After this, nr_running stays zero and need_more_worker() - * and keep_working() are always true as long as the - * worklist is not empty. This pool now behaves as an - * unbound (in terms of concurrency management) pool which + * The handling of nr_running in sched callbacks are disabled + * now. Zap nr_running. After this, nr_running stays zero and + * need_more_worker() and keep_working() are always true as + * long as the worklist is not empty. This pool now behaves as + * an unbound (in terms of concurrency management) pool which * are served by workers tied to the pool. */ - atomic_set(&pool->nr_running, 0); + pool->nr_running = 0; /* * With concurrency management just turned off, a busy * worker blocking could lead to lengthy stalls. Kick off * unbound chain execution of currently pending work items. */ - spin_lock_irq(&pool->lock); - wake_up_worker(pool); - spin_unlock_irq(&pool->lock); + kick_pool(pool); + + raw_spin_unlock_irq(&pool->lock); + + for_each_pool_worker(worker, pool) + unbind_worker(worker); + + mutex_unlock(&wq_pool_attach_mutex); } } @@ -4552,36 +6589,28 @@ static void wq_unbind_fn(struct work_struct *work) static void rebind_workers(struct worker_pool *pool) { struct worker *worker; - int wi; - lockdep_assert_held(&pool->manager_mutex); + lockdep_assert_held(&wq_pool_attach_mutex); /* * Restore CPU affinity of all workers. As all idle workers should * be on the run-queue of the associated CPU before any local - * wake-ups for concurrency management happen, restore CPU affinty + * wake-ups for concurrency management happen, restore CPU affinity * of all workers first and then clear UNBOUND. As we're called * from CPU_ONLINE, the following shouldn't fail. */ - for_each_pool_worker(worker, wi, pool) + for_each_pool_worker(worker, pool) { + kthread_set_per_cpu(worker->task, pool->cpu); WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, - pool->attrs->cpumask) < 0); + pool_allowed_cpus(pool)) < 0); + } - spin_lock_irq(&pool->lock); + raw_spin_lock_irq(&pool->lock); - for_each_pool_worker(worker, wi, pool) { - unsigned int worker_flags = worker->flags; + pool->flags &= ~POOL_DISASSOCIATED; - /* - * A bound idle worker should actually be on the runqueue - * of the associated CPU for local wake-ups targeting it to - * work. Kick all idle workers so that they migrate to the - * associated CPU. Doing this in the same loop as - * replacing UNBOUND with REBOUND is safe as no worker will - * be bound before @pool->lock is released. - */ - if (worker_flags & WORKER_IDLE) - wake_up_process(worker->task); + for_each_pool_worker(worker, pool) { + unsigned int worker_flags = worker->flags; /* * We want to clear UNBOUND but can't directly call @@ -4592,19 +6621,19 @@ static void rebind_workers(struct worker_pool *pool) * concurrency management. Note that when or whether * @worker clears REBOUND doesn't affect correctness. * - * ACCESS_ONCE() is necessary because @worker->flags may be + * WRITE_ONCE() is necessary because @worker->flags may be * tested without holding any lock in - * wq_worker_waking_up(). Without it, NOT_RUNNING test may + * wq_worker_running(). Without it, NOT_RUNNING test may * fail incorrectly leading to premature concurrency * management operations. */ WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND)); worker_flags |= WORKER_REBOUND; worker_flags &= ~WORKER_UNBOUND; - ACCESS_ONCE(worker->flags) = worker_flags; + WRITE_ONCE(worker->flags, worker_flags); } - spin_unlock_irq(&pool->lock); + raw_spin_unlock_irq(&pool->lock); } /** @@ -4621,110 +6650,111 @@ static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu) { static cpumask_t cpumask; struct worker *worker; - int wi; - lockdep_assert_held(&pool->manager_mutex); + lockdep_assert_held(&wq_pool_attach_mutex); /* is @cpu allowed for @pool? */ if (!cpumask_test_cpu(cpu, pool->attrs->cpumask)) return; - /* is @cpu the only online CPU? */ cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask); - if (cpumask_weight(&cpumask) != 1) - return; /* as we're called from CPU_ONLINE, the following shouldn't fail */ - for_each_pool_worker(worker, wi, pool) - WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, - pool->attrs->cpumask) < 0); + for_each_pool_worker(worker, pool) + WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, &cpumask) < 0); } -/* - * Workqueues should be brought up before normal priority CPU notifiers. - * This will be registered high priority CPU notifier. - */ -static int __cpuinit workqueue_cpu_up_callback(struct notifier_block *nfb, - unsigned long action, - void *hcpu) +int workqueue_prepare_cpu(unsigned int cpu) +{ + struct worker_pool *pool; + + for_each_cpu_worker_pool(pool, cpu) { + if (pool->nr_workers) + continue; + if (!create_worker(pool)) + return -ENOMEM; + } + return 0; +} + +int workqueue_online_cpu(unsigned int cpu) { - int cpu = (unsigned long)hcpu; struct worker_pool *pool; struct workqueue_struct *wq; int pi; - switch (action & ~CPU_TASKS_FROZEN) { - case CPU_UP_PREPARE: - for_each_cpu_worker_pool(pool, cpu) { - if (pool->nr_workers) - continue; - if (create_and_start_worker(pool) < 0) - return NOTIFY_BAD; - } - break; + mutex_lock(&wq_pool_mutex); - case CPU_DOWN_FAILED: - case CPU_ONLINE: - mutex_lock(&wq_pool_mutex); + cpumask_set_cpu(cpu, wq_online_cpumask); - for_each_pool(pool, pi) { - mutex_lock(&pool->manager_mutex); + for_each_pool(pool, pi) { + /* BH pools aren't affected by hotplug */ + if (pool->flags & POOL_BH) + continue; - if (pool->cpu == cpu) { - spin_lock_irq(&pool->lock); - pool->flags &= ~POOL_DISASSOCIATED; - spin_unlock_irq(&pool->lock); + mutex_lock(&wq_pool_attach_mutex); + if (pool->cpu == cpu) + rebind_workers(pool); + else if (pool->cpu < 0) + restore_unbound_workers_cpumask(pool, cpu); + mutex_unlock(&wq_pool_attach_mutex); + } - rebind_workers(pool); - } else if (pool->cpu < 0) { - restore_unbound_workers_cpumask(pool, cpu); - } + /* update pod affinity of unbound workqueues */ + list_for_each_entry(wq, &workqueues, list) { + struct workqueue_attrs *attrs = wq->unbound_attrs; - mutex_unlock(&pool->manager_mutex); - } + if (attrs) { + const struct wq_pod_type *pt = wqattrs_pod_type(attrs); + int tcpu; - /* update NUMA affinity of unbound workqueues */ - list_for_each_entry(wq, &workqueues, list) - wq_update_unbound_numa(wq, cpu, true); + for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]]) + unbound_wq_update_pwq(wq, tcpu); - mutex_unlock(&wq_pool_mutex); - break; + mutex_lock(&wq->mutex); + wq_update_node_max_active(wq, -1); + mutex_unlock(&wq->mutex); + } } - return NOTIFY_OK; + + mutex_unlock(&wq_pool_mutex); + return 0; } -/* - * Workqueues should be brought down after normal priority CPU notifiers. - * This will be registered as low priority CPU notifier. - */ -static int __cpuinit workqueue_cpu_down_callback(struct notifier_block *nfb, - unsigned long action, - void *hcpu) +int workqueue_offline_cpu(unsigned int cpu) { - int cpu = (unsigned long)hcpu; - struct work_struct unbind_work; struct workqueue_struct *wq; - switch (action & ~CPU_TASKS_FROZEN) { - case CPU_DOWN_PREPARE: - /* unbinding per-cpu workers should happen on the local CPU */ - INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn); - queue_work_on(cpu, system_highpri_wq, &unbind_work); + /* unbinding per-cpu workers should happen on the local CPU */ + if (WARN_ON(cpu != smp_processor_id())) + return -1; - /* update NUMA affinity of unbound workqueues */ - mutex_lock(&wq_pool_mutex); - list_for_each_entry(wq, &workqueues, list) - wq_update_unbound_numa(wq, cpu, false); - mutex_unlock(&wq_pool_mutex); + unbind_workers(cpu); + + /* update pod affinity of unbound workqueues */ + mutex_lock(&wq_pool_mutex); + + cpumask_clear_cpu(cpu, wq_online_cpumask); + + list_for_each_entry(wq, &workqueues, list) { + struct workqueue_attrs *attrs = wq->unbound_attrs; - /* wait for per-cpu unbinding to finish */ - flush_work(&unbind_work); - break; + if (attrs) { + const struct wq_pod_type *pt = wqattrs_pod_type(attrs); + int tcpu; + + for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]]) + unbound_wq_update_pwq(wq, tcpu); + + mutex_lock(&wq->mutex); + wq_update_node_max_active(wq, cpu); + mutex_unlock(&wq->mutex); + } } - return NOTIFY_OK; -} + mutex_unlock(&wq_pool_mutex); -#ifdef CONFIG_SMP + return 0; +} struct work_for_cpu { struct work_struct work; @@ -4741,25 +6771,29 @@ static void work_for_cpu_fn(struct work_struct *work) } /** - * work_on_cpu - run a function in user context on a particular cpu + * work_on_cpu_key - run a function in thread context on a particular cpu * @cpu: the cpu to run on * @fn: the function to run * @arg: the function arg + * @key: The lock class key for lock debugging purposes * - * This will return the value @fn returns. * It is up to the caller to ensure that the cpu doesn't go offline. * The caller must not hold any locks which would prevent @fn from completing. + * + * Return: The value @fn returns. */ -long work_on_cpu(int cpu, long (*fn)(void *), void *arg) +long work_on_cpu_key(int cpu, long (*fn)(void *), + void *arg, struct lock_class_key *key) { struct work_for_cpu wfc = { .fn = fn, .arg = arg }; - INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); + INIT_WORK_ONSTACK_KEY(&wfc.work, work_for_cpu_fn, key); schedule_work_on(cpu, &wfc.work); flush_work(&wfc.work); + destroy_work_on_stack(&wfc.work); return wfc.ret; } -EXPORT_SYMBOL_GPL(work_on_cpu); +EXPORT_SYMBOL_GPL(work_on_cpu_key); #endif /* CONFIG_SMP */ #ifdef CONFIG_FREEZER @@ -4768,7 +6802,7 @@ EXPORT_SYMBOL_GPL(work_on_cpu); * freeze_workqueues_begin - begin freezing workqueues * * Start freezing workqueues. After this function returns, all freezable - * workqueues will queue new works to their delayed_works list instead of + * workqueues will queue new works to their inactive_works list instead of * pool->worklist. * * CONTEXT: @@ -4776,28 +6810,16 @@ EXPORT_SYMBOL_GPL(work_on_cpu); */ void freeze_workqueues_begin(void) { - struct worker_pool *pool; struct workqueue_struct *wq; - struct pool_workqueue *pwq; - int pi; mutex_lock(&wq_pool_mutex); WARN_ON_ONCE(workqueue_freezing); workqueue_freezing = true; - /* set FREEZING */ - for_each_pool(pool, pi) { - spin_lock_irq(&pool->lock); - WARN_ON_ONCE(pool->flags & POOL_FREEZING); - pool->flags |= POOL_FREEZING; - spin_unlock_irq(&pool->lock); - } - list_for_each_entry(wq, &workqueues, list) { mutex_lock(&wq->mutex); - for_each_pwq(pwq, wq) - pwq_adjust_max_active(pwq); + wq_adjust_max_active(wq); mutex_unlock(&wq->mutex); } @@ -4813,7 +6835,7 @@ void freeze_workqueues_begin(void) * CONTEXT: * Grabs and releases wq_pool_mutex. * - * RETURNS: + * Return: * %true if some freezable workqueues are still busy. %false if freezing * is complete. */ @@ -4834,16 +6856,16 @@ bool freeze_workqueues_busy(void) * nr_active is monotonically decreasing. It's safe * to peek without lock. */ - rcu_read_lock_sched(); + rcu_read_lock(); for_each_pwq(pwq, wq) { WARN_ON_ONCE(pwq->nr_active < 0); if (pwq->nr_active) { busy = true; - rcu_read_unlock_sched(); + rcu_read_unlock(); goto out_unlock; } } - rcu_read_unlock_sched(); + rcu_read_unlock(); } out_unlock: mutex_unlock(&wq_pool_mutex); @@ -4862,155 +6884,1203 @@ out_unlock: void thaw_workqueues(void) { struct workqueue_struct *wq; - struct pool_workqueue *pwq; - struct worker_pool *pool; - int pi; mutex_lock(&wq_pool_mutex); if (!workqueue_freezing) goto out_unlock; - /* clear FREEZING */ - for_each_pool(pool, pi) { - spin_lock_irq(&pool->lock); - WARN_ON_ONCE(!(pool->flags & POOL_FREEZING)); - pool->flags &= ~POOL_FREEZING; - spin_unlock_irq(&pool->lock); - } + workqueue_freezing = false; /* restore max_active and repopulate worklist */ list_for_each_entry(wq, &workqueues, list) { mutex_lock(&wq->mutex); - for_each_pwq(pwq, wq) - pwq_adjust_max_active(pwq); + wq_adjust_max_active(wq); mutex_unlock(&wq->mutex); } - workqueue_freezing = false; out_unlock: mutex_unlock(&wq_pool_mutex); } #endif /* CONFIG_FREEZER */ -static void __init wq_numa_init(void) +static int workqueue_apply_unbound_cpumask(const cpumask_var_t unbound_cpumask) { - cpumask_var_t *tbl; - int node, cpu; + LIST_HEAD(ctxs); + int ret = 0; + struct workqueue_struct *wq; + struct apply_wqattrs_ctx *ctx, *n; - /* determine NUMA pwq table len - highest node id + 1 */ - for_each_node(node) - wq_numa_tbl_len = max(wq_numa_tbl_len, node + 1); + lockdep_assert_held(&wq_pool_mutex); - if (num_possible_nodes() <= 1) - return; + list_for_each_entry(wq, &workqueues, list) { + if (!(wq->flags & WQ_UNBOUND) || (wq->flags & __WQ_DESTROYING)) + continue; - if (wq_disable_numa) { - pr_info("workqueue: NUMA affinity support disabled\n"); - return; + ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs, unbound_cpumask); + if (IS_ERR(ctx)) { + ret = PTR_ERR(ctx); + break; + } + + list_add_tail(&ctx->list, &ctxs); + } + + list_for_each_entry_safe(ctx, n, &ctxs, list) { + if (!ret) + apply_wqattrs_commit(ctx); + apply_wqattrs_cleanup(ctx); } - wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs(GFP_KERNEL); - BUG_ON(!wq_update_unbound_numa_attrs_buf); + if (!ret) { + int cpu; + struct worker_pool *pool; + struct worker *worker; + + mutex_lock(&wq_pool_attach_mutex); + cpumask_copy(wq_unbound_cpumask, unbound_cpumask); + /* rescuer needs to respect cpumask changes when it is not attached */ + list_for_each_entry(wq, &workqueues, list) { + if (wq->rescuer && !wq->rescuer->pool) + unbind_worker(wq->rescuer); + } + /* DISASSOCIATED worker needs to respect wq_unbound_cpumask */ + for_each_possible_cpu(cpu) { + for_each_cpu_worker_pool(pool, cpu) { + if (!(pool->flags & POOL_DISASSOCIATED)) + continue; + for_each_pool_worker(worker, pool) + unbind_worker(worker); + } + } + mutex_unlock(&wq_pool_attach_mutex); + } + return ret; +} + +/** + * workqueue_unbound_exclude_cpumask - Exclude given CPUs from unbound cpumask + * @exclude_cpumask: the cpumask to be excluded from wq_unbound_cpumask + * + * This function can be called from cpuset code to provide a set of isolated + * CPUs that should be excluded from wq_unbound_cpumask. + */ +int workqueue_unbound_exclude_cpumask(cpumask_var_t exclude_cpumask) +{ + cpumask_var_t cpumask; + int ret = 0; + + if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL)) + return -ENOMEM; + + mutex_lock(&wq_pool_mutex); /* - * We want masks of possible CPUs of each node which isn't readily - * available. Build one from cpu_to_node() which should have been - * fully initialized by now. + * If the operation fails, it will fall back to + * wq_requested_unbound_cpumask which is initially set to + * (HK_TYPE_WQ ∩ HK_TYPE_DOMAIN) house keeping mask and rewritten + * by any subsequent write to workqueue/cpumask sysfs file. */ - tbl = kzalloc(wq_numa_tbl_len * sizeof(tbl[0]), GFP_KERNEL); - BUG_ON(!tbl); + if (!cpumask_andnot(cpumask, wq_requested_unbound_cpumask, exclude_cpumask)) + cpumask_copy(cpumask, wq_requested_unbound_cpumask); + if (!cpumask_equal(cpumask, wq_unbound_cpumask)) + ret = workqueue_apply_unbound_cpumask(cpumask); - for_each_node(node) - BUG_ON(!alloc_cpumask_var_node(&tbl[node], GFP_KERNEL, - node_online(node) ? node : NUMA_NO_NODE)); + /* Save the current isolated cpumask & export it via sysfs */ + if (!ret) + cpumask_copy(wq_isolated_cpumask, exclude_cpumask); - for_each_possible_cpu(cpu) { - node = cpu_to_node(cpu); - if (WARN_ON(node == NUMA_NO_NODE)) { - pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu); - /* happens iff arch is bonkers, let's just proceed */ - return; + mutex_unlock(&wq_pool_mutex); + free_cpumask_var(cpumask); + return ret; +} + +static int parse_affn_scope(const char *val) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(wq_affn_names); i++) { + if (!strncasecmp(val, wq_affn_names[i], strlen(wq_affn_names[i]))) + return i; + } + return -EINVAL; +} + +static int wq_affn_dfl_set(const char *val, const struct kernel_param *kp) +{ + struct workqueue_struct *wq; + int affn, cpu; + + affn = parse_affn_scope(val); + if (affn < 0) + return affn; + if (affn == WQ_AFFN_DFL) + return -EINVAL; + + cpus_read_lock(); + mutex_lock(&wq_pool_mutex); + + wq_affn_dfl = affn; + + list_for_each_entry(wq, &workqueues, list) { + for_each_online_cpu(cpu) + unbound_wq_update_pwq(wq, cpu); + } + + mutex_unlock(&wq_pool_mutex); + cpus_read_unlock(); + + return 0; +} + +static int wq_affn_dfl_get(char *buffer, const struct kernel_param *kp) +{ + return scnprintf(buffer, PAGE_SIZE, "%s\n", wq_affn_names[wq_affn_dfl]); +} + +static const struct kernel_param_ops wq_affn_dfl_ops = { + .set = wq_affn_dfl_set, + .get = wq_affn_dfl_get, +}; + +module_param_cb(default_affinity_scope, &wq_affn_dfl_ops, NULL, 0644); + +#ifdef CONFIG_SYSFS +/* + * Workqueues with WQ_SYSFS flag set is visible to userland via + * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the + * following attributes. + * + * per_cpu RO bool : whether the workqueue is per-cpu or unbound + * max_active RW int : maximum number of in-flight work items + * + * Unbound workqueues have the following extra attributes. + * + * nice RW int : nice value of the workers + * cpumask RW mask : bitmask of allowed CPUs for the workers + * affinity_scope RW str : worker CPU affinity scope (cache, numa, none) + * affinity_strict RW bool : worker CPU affinity is strict + */ +struct wq_device { + struct workqueue_struct *wq; + struct device dev; +}; + +static struct workqueue_struct *dev_to_wq(struct device *dev) +{ + struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); + + return wq_dev->wq; +} + +static ssize_t per_cpu_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct workqueue_struct *wq = dev_to_wq(dev); + + return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND)); +} +static DEVICE_ATTR_RO(per_cpu); + +static ssize_t max_active_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct workqueue_struct *wq = dev_to_wq(dev); + + return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active); +} + +static ssize_t max_active_store(struct device *dev, + struct device_attribute *attr, const char *buf, + size_t count) +{ + struct workqueue_struct *wq = dev_to_wq(dev); + int val; + + if (sscanf(buf, "%d", &val) != 1 || val <= 0) + return -EINVAL; + + workqueue_set_max_active(wq, val); + return count; +} +static DEVICE_ATTR_RW(max_active); + +static struct attribute *wq_sysfs_attrs[] = { + &dev_attr_per_cpu.attr, + &dev_attr_max_active.attr, + NULL, +}; +ATTRIBUTE_GROUPS(wq_sysfs); + +static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct workqueue_struct *wq = dev_to_wq(dev); + int written; + + mutex_lock(&wq->mutex); + written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice); + mutex_unlock(&wq->mutex); + + return written; +} + +/* prepare workqueue_attrs for sysfs store operations */ +static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq) +{ + struct workqueue_attrs *attrs; + + lockdep_assert_held(&wq_pool_mutex); + + attrs = alloc_workqueue_attrs(); + if (!attrs) + return NULL; + + copy_workqueue_attrs(attrs, wq->unbound_attrs); + return attrs; +} + +static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct workqueue_struct *wq = dev_to_wq(dev); + struct workqueue_attrs *attrs; + int ret = -ENOMEM; + + apply_wqattrs_lock(); + + attrs = wq_sysfs_prep_attrs(wq); + if (!attrs) + goto out_unlock; + + if (sscanf(buf, "%d", &attrs->nice) == 1 && + attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE) + ret = apply_workqueue_attrs_locked(wq, attrs); + else + ret = -EINVAL; + +out_unlock: + apply_wqattrs_unlock(); + free_workqueue_attrs(attrs); + return ret ?: count; +} + +static ssize_t wq_cpumask_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct workqueue_struct *wq = dev_to_wq(dev); + int written; + + mutex_lock(&wq->mutex); + written = scnprintf(buf, PAGE_SIZE, "%*pb\n", + cpumask_pr_args(wq->unbound_attrs->cpumask)); + mutex_unlock(&wq->mutex); + return written; +} + +static ssize_t wq_cpumask_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct workqueue_struct *wq = dev_to_wq(dev); + struct workqueue_attrs *attrs; + int ret = -ENOMEM; + + apply_wqattrs_lock(); + + attrs = wq_sysfs_prep_attrs(wq); + if (!attrs) + goto out_unlock; + + ret = cpumask_parse(buf, attrs->cpumask); + if (!ret) + ret = apply_workqueue_attrs_locked(wq, attrs); + +out_unlock: + apply_wqattrs_unlock(); + free_workqueue_attrs(attrs); + return ret ?: count; +} + +static ssize_t wq_affn_scope_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct workqueue_struct *wq = dev_to_wq(dev); + int written; + + mutex_lock(&wq->mutex); + if (wq->unbound_attrs->affn_scope == WQ_AFFN_DFL) + written = scnprintf(buf, PAGE_SIZE, "%s (%s)\n", + wq_affn_names[WQ_AFFN_DFL], + wq_affn_names[wq_affn_dfl]); + else + written = scnprintf(buf, PAGE_SIZE, "%s\n", + wq_affn_names[wq->unbound_attrs->affn_scope]); + mutex_unlock(&wq->mutex); + + return written; +} + +static ssize_t wq_affn_scope_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct workqueue_struct *wq = dev_to_wq(dev); + struct workqueue_attrs *attrs; + int affn, ret = -ENOMEM; + + affn = parse_affn_scope(buf); + if (affn < 0) + return affn; + + apply_wqattrs_lock(); + attrs = wq_sysfs_prep_attrs(wq); + if (attrs) { + attrs->affn_scope = affn; + ret = apply_workqueue_attrs_locked(wq, attrs); + } + apply_wqattrs_unlock(); + free_workqueue_attrs(attrs); + return ret ?: count; +} + +static ssize_t wq_affinity_strict_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct workqueue_struct *wq = dev_to_wq(dev); + + return scnprintf(buf, PAGE_SIZE, "%d\n", + wq->unbound_attrs->affn_strict); +} + +static ssize_t wq_affinity_strict_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct workqueue_struct *wq = dev_to_wq(dev); + struct workqueue_attrs *attrs; + int v, ret = -ENOMEM; + + if (sscanf(buf, "%d", &v) != 1) + return -EINVAL; + + apply_wqattrs_lock(); + attrs = wq_sysfs_prep_attrs(wq); + if (attrs) { + attrs->affn_strict = (bool)v; + ret = apply_workqueue_attrs_locked(wq, attrs); + } + apply_wqattrs_unlock(); + free_workqueue_attrs(attrs); + return ret ?: count; +} + +static struct device_attribute wq_sysfs_unbound_attrs[] = { + __ATTR(nice, 0644, wq_nice_show, wq_nice_store), + __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store), + __ATTR(affinity_scope, 0644, wq_affn_scope_show, wq_affn_scope_store), + __ATTR(affinity_strict, 0644, wq_affinity_strict_show, wq_affinity_strict_store), + __ATTR_NULL, +}; + +static const struct bus_type wq_subsys = { + .name = "workqueue", + .dev_groups = wq_sysfs_groups, +}; + +/** + * workqueue_set_unbound_cpumask - Set the low-level unbound cpumask + * @cpumask: the cpumask to set + * + * The low-level workqueues cpumask is a global cpumask that limits + * the affinity of all unbound workqueues. This function check the @cpumask + * and apply it to all unbound workqueues and updates all pwqs of them. + * + * Return: 0 - Success + * -EINVAL - Invalid @cpumask + * -ENOMEM - Failed to allocate memory for attrs or pwqs. + */ +static int workqueue_set_unbound_cpumask(cpumask_var_t cpumask) +{ + int ret = -EINVAL; + + /* + * Not excluding isolated cpus on purpose. + * If the user wishes to include them, we allow that. + */ + cpumask_and(cpumask, cpumask, cpu_possible_mask); + if (!cpumask_empty(cpumask)) { + ret = 0; + apply_wqattrs_lock(); + if (!cpumask_equal(cpumask, wq_unbound_cpumask)) + ret = workqueue_apply_unbound_cpumask(cpumask); + if (!ret) + cpumask_copy(wq_requested_unbound_cpumask, cpumask); + apply_wqattrs_unlock(); + } + + return ret; +} + +static ssize_t __wq_cpumask_show(struct device *dev, + struct device_attribute *attr, char *buf, cpumask_var_t mask) +{ + int written; + + mutex_lock(&wq_pool_mutex); + written = scnprintf(buf, PAGE_SIZE, "%*pb\n", cpumask_pr_args(mask)); + mutex_unlock(&wq_pool_mutex); + + return written; +} + +static ssize_t cpumask_requested_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return __wq_cpumask_show(dev, attr, buf, wq_requested_unbound_cpumask); +} +static DEVICE_ATTR_RO(cpumask_requested); + +static ssize_t cpumask_isolated_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return __wq_cpumask_show(dev, attr, buf, wq_isolated_cpumask); +} +static DEVICE_ATTR_RO(cpumask_isolated); + +static ssize_t cpumask_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return __wq_cpumask_show(dev, attr, buf, wq_unbound_cpumask); +} + +static ssize_t cpumask_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t count) +{ + cpumask_var_t cpumask; + int ret; + + if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL)) + return -ENOMEM; + + ret = cpumask_parse(buf, cpumask); + if (!ret) + ret = workqueue_set_unbound_cpumask(cpumask); + + free_cpumask_var(cpumask); + return ret ? ret : count; +} +static DEVICE_ATTR_RW(cpumask); + +static struct attribute *wq_sysfs_cpumask_attrs[] = { + &dev_attr_cpumask.attr, + &dev_attr_cpumask_requested.attr, + &dev_attr_cpumask_isolated.attr, + NULL, +}; +ATTRIBUTE_GROUPS(wq_sysfs_cpumask); + +static int __init wq_sysfs_init(void) +{ + return subsys_virtual_register(&wq_subsys, wq_sysfs_cpumask_groups); +} +core_initcall(wq_sysfs_init); + +static void wq_device_release(struct device *dev) +{ + struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); + + kfree(wq_dev); +} + +/** + * workqueue_sysfs_register - make a workqueue visible in sysfs + * @wq: the workqueue to register + * + * Expose @wq in sysfs under /sys/bus/workqueue/devices. + * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set + * which is the preferred method. + * + * Workqueue user should use this function directly iff it wants to apply + * workqueue_attrs before making the workqueue visible in sysfs; otherwise, + * apply_workqueue_attrs() may race against userland updating the + * attributes. + * + * Return: 0 on success, -errno on failure. + */ +int workqueue_sysfs_register(struct workqueue_struct *wq) +{ + struct wq_device *wq_dev; + int ret; + + /* + * Adjusting max_active breaks ordering guarantee. Disallow exposing + * ordered workqueues. + */ + if (WARN_ON(wq->flags & __WQ_ORDERED)) + return -EINVAL; + + wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL); + if (!wq_dev) + return -ENOMEM; + + wq_dev->wq = wq; + wq_dev->dev.bus = &wq_subsys; + wq_dev->dev.release = wq_device_release; + dev_set_name(&wq_dev->dev, "%s", wq->name); + + /* + * unbound_attrs are created separately. Suppress uevent until + * everything is ready. + */ + dev_set_uevent_suppress(&wq_dev->dev, true); + + ret = device_register(&wq_dev->dev); + if (ret) { + put_device(&wq_dev->dev); + wq->wq_dev = NULL; + return ret; + } + + if (wq->flags & WQ_UNBOUND) { + struct device_attribute *attr; + + for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) { + ret = device_create_file(&wq_dev->dev, attr); + if (ret) { + device_unregister(&wq_dev->dev); + wq->wq_dev = NULL; + return ret; + } + } + } + + dev_set_uevent_suppress(&wq_dev->dev, false); + kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD); + return 0; +} + +/** + * workqueue_sysfs_unregister - undo workqueue_sysfs_register() + * @wq: the workqueue to unregister + * + * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister. + */ +static void workqueue_sysfs_unregister(struct workqueue_struct *wq) +{ + struct wq_device *wq_dev = wq->wq_dev; + + if (!wq->wq_dev) + return; + + wq->wq_dev = NULL; + device_unregister(&wq_dev->dev); +} +#else /* CONFIG_SYSFS */ +static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { } +#endif /* CONFIG_SYSFS */ + +/* + * Workqueue watchdog. + * + * Stall may be caused by various bugs - missing WQ_MEM_RECLAIM, illegal + * flush dependency, a concurrency managed work item which stays RUNNING + * indefinitely. Workqueue stalls can be very difficult to debug as the + * usual warning mechanisms don't trigger and internal workqueue state is + * largely opaque. + * + * Workqueue watchdog monitors all worker pools periodically and dumps + * state if some pools failed to make forward progress for a while where + * forward progress is defined as the first item on ->worklist changing. + * + * This mechanism is controlled through the kernel parameter + * "workqueue.watchdog_thresh" which can be updated at runtime through the + * corresponding sysfs parameter file. + */ +#ifdef CONFIG_WQ_WATCHDOG + +static unsigned long wq_watchdog_thresh = 30; +static struct timer_list wq_watchdog_timer; + +static unsigned long wq_watchdog_touched = INITIAL_JIFFIES; +static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES; + +static unsigned int wq_panic_on_stall; +module_param_named(panic_on_stall, wq_panic_on_stall, uint, 0644); + +/* + * Show workers that might prevent the processing of pending work items. + * The only candidates are CPU-bound workers in the running state. + * Pending work items should be handled by another idle worker + * in all other situations. + */ +static void show_cpu_pool_hog(struct worker_pool *pool) +{ + struct worker *worker; + unsigned long irq_flags; + int bkt; + + raw_spin_lock_irqsave(&pool->lock, irq_flags); + + hash_for_each(pool->busy_hash, bkt, worker, hentry) { + if (task_is_running(worker->task)) { + /* + * Defer printing to avoid deadlocks in console + * drivers that queue work while holding locks + * also taken in their write paths. + */ + printk_deferred_enter(); + + pr_info("pool %d:\n", pool->id); + sched_show_task(worker->task); + + printk_deferred_exit(); + } + } + + raw_spin_unlock_irqrestore(&pool->lock, irq_flags); +} + +static void show_cpu_pools_hogs(void) +{ + struct worker_pool *pool; + int pi; + + pr_info("Showing backtraces of running workers in stalled CPU-bound worker pools:\n"); + + rcu_read_lock(); + + for_each_pool(pool, pi) { + if (pool->cpu_stall) + show_cpu_pool_hog(pool); + + } + + rcu_read_unlock(); +} + +static void panic_on_wq_watchdog(void) +{ + static unsigned int wq_stall; + + if (wq_panic_on_stall) { + wq_stall++; + BUG_ON(wq_stall >= wq_panic_on_stall); + } +} + +static void wq_watchdog_reset_touched(void) +{ + int cpu; + + wq_watchdog_touched = jiffies; + for_each_possible_cpu(cpu) + per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies; +} + +static void wq_watchdog_timer_fn(struct timer_list *unused) +{ + unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ; + bool lockup_detected = false; + bool cpu_pool_stall = false; + unsigned long now = jiffies; + struct worker_pool *pool; + int pi; + + if (!thresh) + return; + + for_each_pool(pool, pi) { + unsigned long pool_ts, touched, ts; + + pool->cpu_stall = false; + if (list_empty(&pool->worklist)) + continue; + + /* + * If a virtual machine is stopped by the host it can look to + * the watchdog like a stall. + */ + kvm_check_and_clear_guest_paused(); + + /* get the latest of pool and touched timestamps */ + if (pool->cpu >= 0) + touched = READ_ONCE(per_cpu(wq_watchdog_touched_cpu, pool->cpu)); + else + touched = READ_ONCE(wq_watchdog_touched); + pool_ts = READ_ONCE(pool->watchdog_ts); + + if (time_after(pool_ts, touched)) + ts = pool_ts; + else + ts = touched; + + /* did we stall? */ + if (time_after(now, ts + thresh)) { + lockup_detected = true; + if (pool->cpu >= 0 && !(pool->flags & POOL_BH)) { + pool->cpu_stall = true; + cpu_pool_stall = true; + } + pr_emerg("BUG: workqueue lockup - pool"); + pr_cont_pool_info(pool); + pr_cont(" stuck for %us!\n", + jiffies_to_msecs(now - pool_ts) / 1000); } - cpumask_set_cpu(cpu, tbl[node]); + + + } + + if (lockup_detected) + show_all_workqueues(); + + if (cpu_pool_stall) + show_cpu_pools_hogs(); + + if (lockup_detected) + panic_on_wq_watchdog(); + + wq_watchdog_reset_touched(); + mod_timer(&wq_watchdog_timer, jiffies + thresh); +} + +notrace void wq_watchdog_touch(int cpu) +{ + unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ; + unsigned long touch_ts = READ_ONCE(wq_watchdog_touched); + unsigned long now = jiffies; + + if (cpu >= 0) + per_cpu(wq_watchdog_touched_cpu, cpu) = now; + else + WARN_ONCE(1, "%s should be called with valid CPU", __func__); + + /* Don't unnecessarily store to global cacheline */ + if (time_after(now, touch_ts + thresh / 4)) + WRITE_ONCE(wq_watchdog_touched, jiffies); +} + +static void wq_watchdog_set_thresh(unsigned long thresh) +{ + wq_watchdog_thresh = 0; + timer_delete_sync(&wq_watchdog_timer); + + if (thresh) { + wq_watchdog_thresh = thresh; + wq_watchdog_reset_touched(); + mod_timer(&wq_watchdog_timer, jiffies + thresh * HZ); + } +} + +static int wq_watchdog_param_set_thresh(const char *val, + const struct kernel_param *kp) +{ + unsigned long thresh; + int ret; + + ret = kstrtoul(val, 0, &thresh); + if (ret) + return ret; + + if (system_percpu_wq) + wq_watchdog_set_thresh(thresh); + else + wq_watchdog_thresh = thresh; + + return 0; +} + +static const struct kernel_param_ops wq_watchdog_thresh_ops = { + .set = wq_watchdog_param_set_thresh, + .get = param_get_ulong, +}; + +module_param_cb(watchdog_thresh, &wq_watchdog_thresh_ops, &wq_watchdog_thresh, + 0644); + +static void wq_watchdog_init(void) +{ + timer_setup(&wq_watchdog_timer, wq_watchdog_timer_fn, TIMER_DEFERRABLE); + wq_watchdog_set_thresh(wq_watchdog_thresh); +} + +#else /* CONFIG_WQ_WATCHDOG */ + +static inline void wq_watchdog_init(void) { } + +#endif /* CONFIG_WQ_WATCHDOG */ + +static void bh_pool_kick_normal(struct irq_work *irq_work) +{ + raise_softirq_irqoff(TASKLET_SOFTIRQ); +} + +static void bh_pool_kick_highpri(struct irq_work *irq_work) +{ + raise_softirq_irqoff(HI_SOFTIRQ); +} + +static void __init restrict_unbound_cpumask(const char *name, const struct cpumask *mask) +{ + if (!cpumask_intersects(wq_unbound_cpumask, mask)) { + pr_warn("workqueue: Restricting unbound_cpumask (%*pb) with %s (%*pb) leaves no CPU, ignoring\n", + cpumask_pr_args(wq_unbound_cpumask), name, cpumask_pr_args(mask)); + return; } - wq_numa_possible_cpumask = tbl; - wq_numa_enabled = true; + cpumask_and(wq_unbound_cpumask, wq_unbound_cpumask, mask); +} + +static void __init init_cpu_worker_pool(struct worker_pool *pool, int cpu, int nice) +{ + BUG_ON(init_worker_pool(pool)); + pool->cpu = cpu; + cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu)); + cpumask_copy(pool->attrs->__pod_cpumask, cpumask_of(cpu)); + pool->attrs->nice = nice; + pool->attrs->affn_strict = true; + pool->node = cpu_to_node(cpu); + + /* alloc pool ID */ + mutex_lock(&wq_pool_mutex); + BUG_ON(worker_pool_assign_id(pool)); + mutex_unlock(&wq_pool_mutex); } -static int __init init_workqueues(void) +/** + * workqueue_init_early - early init for workqueue subsystem + * + * This is the first step of three-staged workqueue subsystem initialization and + * invoked as soon as the bare basics - memory allocation, cpumasks and idr are + * up. It sets up all the data structures and system workqueues and allows early + * boot code to create workqueues and queue/cancel work items. Actual work item + * execution starts only after kthreads can be created and scheduled right + * before early initcalls. + */ +void __init workqueue_init_early(void) { + struct wq_pod_type *pt = &wq_pod_types[WQ_AFFN_SYSTEM]; int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL }; + void (*irq_work_fns[2])(struct irq_work *) = { bh_pool_kick_normal, + bh_pool_kick_highpri }; int i, cpu; - /* make sure we have enough bits for OFFQ pool ID */ - BUILD_BUG_ON((1LU << (BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT)) < - WORK_CPU_END * NR_STD_WORKER_POOLS); + BUILD_BUG_ON(__alignof__(struct pool_workqueue) < __alignof__(long long)); + + BUG_ON(!alloc_cpumask_var(&wq_online_cpumask, GFP_KERNEL)); + BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL)); + BUG_ON(!alloc_cpumask_var(&wq_requested_unbound_cpumask, GFP_KERNEL)); + BUG_ON(!zalloc_cpumask_var(&wq_isolated_cpumask, GFP_KERNEL)); - WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long)); + cpumask_copy(wq_online_cpumask, cpu_online_mask); + cpumask_copy(wq_unbound_cpumask, cpu_possible_mask); + restrict_unbound_cpumask("HK_TYPE_WQ", housekeeping_cpumask(HK_TYPE_WQ)); + restrict_unbound_cpumask("HK_TYPE_DOMAIN", housekeeping_cpumask(HK_TYPE_DOMAIN)); + if (!cpumask_empty(&wq_cmdline_cpumask)) + restrict_unbound_cpumask("workqueue.unbound_cpus", &wq_cmdline_cpumask); + cpumask_copy(wq_requested_unbound_cpumask, wq_unbound_cpumask); + cpumask_andnot(wq_isolated_cpumask, cpu_possible_mask, + housekeeping_cpumask(HK_TYPE_DOMAIN)); pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC); - cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP); - hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN); + unbound_wq_update_pwq_attrs_buf = alloc_workqueue_attrs(); + BUG_ON(!unbound_wq_update_pwq_attrs_buf); - wq_numa_init(); + /* + * If nohz_full is enabled, set power efficient workqueue as unbound. + * This allows workqueue items to be moved to HK CPUs. + */ + if (housekeeping_enabled(HK_TYPE_TICK)) + wq_power_efficient = true; - /* initialize CPU pools */ - for_each_possible_cpu(cpu) { - struct worker_pool *pool; + /* initialize WQ_AFFN_SYSTEM pods */ + pt->pod_cpus = kcalloc(1, sizeof(pt->pod_cpus[0]), GFP_KERNEL); + pt->pod_node = kcalloc(1, sizeof(pt->pod_node[0]), GFP_KERNEL); + pt->cpu_pod = kcalloc(nr_cpu_ids, sizeof(pt->cpu_pod[0]), GFP_KERNEL); + BUG_ON(!pt->pod_cpus || !pt->pod_node || !pt->cpu_pod); - i = 0; - for_each_cpu_worker_pool(pool, cpu) { - BUG_ON(init_worker_pool(pool)); - pool->cpu = cpu; - cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu)); - pool->attrs->nice = std_nice[i++]; - pool->node = cpu_to_node(cpu); + BUG_ON(!zalloc_cpumask_var_node(&pt->pod_cpus[0], GFP_KERNEL, NUMA_NO_NODE)); - /* alloc pool ID */ - mutex_lock(&wq_pool_mutex); - BUG_ON(worker_pool_assign_id(pool)); - mutex_unlock(&wq_pool_mutex); - } - } + pt->nr_pods = 1; + cpumask_copy(pt->pod_cpus[0], cpu_possible_mask); + pt->pod_node[0] = NUMA_NO_NODE; + pt->cpu_pod[0] = 0; - /* create the initial worker */ - for_each_online_cpu(cpu) { + /* initialize BH and CPU pools */ + for_each_possible_cpu(cpu) { struct worker_pool *pool; - for_each_cpu_worker_pool(pool, cpu) { - pool->flags &= ~POOL_DISASSOCIATED; - BUG_ON(create_and_start_worker(pool) < 0); + i = 0; + for_each_bh_worker_pool(pool, cpu) { + init_cpu_worker_pool(pool, cpu, std_nice[i]); + pool->flags |= POOL_BH; + init_irq_work(bh_pool_irq_work(pool), irq_work_fns[i]); + i++; } + + i = 0; + for_each_cpu_worker_pool(pool, cpu) + init_cpu_worker_pool(pool, cpu, std_nice[i++]); } - /* create default unbound wq attrs */ + /* create default unbound and ordered wq attrs */ for (i = 0; i < NR_STD_WORKER_POOLS; i++) { struct workqueue_attrs *attrs; - BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL))); + BUG_ON(!(attrs = alloc_workqueue_attrs())); attrs->nice = std_nice[i]; unbound_std_wq_attrs[i] = attrs; + + /* + * An ordered wq should have only one pwq as ordering is + * guaranteed by max_active which is enforced by pwqs. + */ + BUG_ON(!(attrs = alloc_workqueue_attrs())); + attrs->nice = std_nice[i]; + attrs->ordered = true; + ordered_wq_attrs[i] = attrs; } - system_wq = alloc_workqueue("events", 0, 0); - system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); - system_long_wq = alloc_workqueue("events_long", 0, 0); - system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, - WQ_UNBOUND_MAX_ACTIVE); + system_wq = alloc_workqueue("events", WQ_PERCPU, 0); + system_percpu_wq = alloc_workqueue("events", WQ_PERCPU, 0); + system_highpri_wq = alloc_workqueue("events_highpri", + WQ_HIGHPRI | WQ_PERCPU, 0); + system_long_wq = alloc_workqueue("events_long", WQ_PERCPU, 0); + system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, WQ_MAX_ACTIVE); + system_dfl_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, WQ_MAX_ACTIVE); system_freezable_wq = alloc_workqueue("events_freezable", - WQ_FREEZABLE, 0); + WQ_FREEZABLE | WQ_PERCPU, 0); system_power_efficient_wq = alloc_workqueue("events_power_efficient", - WQ_POWER_EFFICIENT, 0); - system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient", - WQ_FREEZABLE | WQ_POWER_EFFICIENT, - 0); - BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || - !system_unbound_wq || !system_freezable_wq || + WQ_POWER_EFFICIENT | WQ_PERCPU, 0); + system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_pwr_efficient", + WQ_FREEZABLE | WQ_POWER_EFFICIENT | WQ_PERCPU, 0); + system_bh_wq = alloc_workqueue("events_bh", WQ_BH | WQ_PERCPU, 0); + system_bh_highpri_wq = alloc_workqueue("events_bh_highpri", + WQ_BH | WQ_HIGHPRI | WQ_PERCPU, 0); + BUG_ON(!system_wq || !system_percpu_wq|| !system_highpri_wq || !system_long_wq || + !system_unbound_wq || !system_freezable_wq || !system_dfl_wq || !system_power_efficient_wq || - !system_freezable_power_efficient_wq); - return 0; + !system_freezable_power_efficient_wq || + !system_bh_wq || !system_bh_highpri_wq); +} + +static void __init wq_cpu_intensive_thresh_init(void) +{ + unsigned long thresh; + unsigned long bogo; + + pwq_release_worker = kthread_run_worker(0, "pool_workqueue_release"); + BUG_ON(IS_ERR(pwq_release_worker)); + + /* if the user set it to a specific value, keep it */ + if (wq_cpu_intensive_thresh_us != ULONG_MAX) + return; + + /* + * The default of 10ms is derived from the fact that most modern (as of + * 2023) processors can do a lot in 10ms and that it's just below what + * most consider human-perceivable. However, the kernel also runs on a + * lot slower CPUs including microcontrollers where the threshold is way + * too low. + * + * Let's scale up the threshold upto 1 second if BogoMips is below 4000. + * This is by no means accurate but it doesn't have to be. The mechanism + * is still useful even when the threshold is fully scaled up. Also, as + * the reports would usually be applicable to everyone, some machines + * operating on longer thresholds won't significantly diminish their + * usefulness. + */ + thresh = 10 * USEC_PER_MSEC; + + /* see init/calibrate.c for lpj -> BogoMIPS calculation */ + bogo = max_t(unsigned long, loops_per_jiffy / 500000 * HZ, 1); + if (bogo < 4000) + thresh = min_t(unsigned long, thresh * 4000 / bogo, USEC_PER_SEC); + + pr_debug("wq_cpu_intensive_thresh: lpj=%lu BogoMIPS=%lu thresh_us=%lu\n", + loops_per_jiffy, bogo, thresh); + + wq_cpu_intensive_thresh_us = thresh; +} + +/** + * workqueue_init - bring workqueue subsystem fully online + * + * This is the second step of three-staged workqueue subsystem initialization + * and invoked as soon as kthreads can be created and scheduled. Workqueues have + * been created and work items queued on them, but there are no kworkers + * executing the work items yet. Populate the worker pools with the initial + * workers and enable future kworker creations. + */ +void __init workqueue_init(void) +{ + struct workqueue_struct *wq; + struct worker_pool *pool; + int cpu, bkt; + + wq_cpu_intensive_thresh_init(); + + mutex_lock(&wq_pool_mutex); + + /* + * Per-cpu pools created earlier could be missing node hint. Fix them + * up. Also, create a rescuer for workqueues that requested it. + */ + for_each_possible_cpu(cpu) { + for_each_bh_worker_pool(pool, cpu) + pool->node = cpu_to_node(cpu); + for_each_cpu_worker_pool(pool, cpu) + pool->node = cpu_to_node(cpu); + } + + list_for_each_entry(wq, &workqueues, list) { + WARN(init_rescuer(wq), + "workqueue: failed to create early rescuer for %s", + wq->name); + } + + mutex_unlock(&wq_pool_mutex); + + /* + * Create the initial workers. A BH pool has one pseudo worker that + * represents the shared BH execution context and thus doesn't get + * affected by hotplug events. Create the BH pseudo workers for all + * possible CPUs here. + */ + for_each_possible_cpu(cpu) + for_each_bh_worker_pool(pool, cpu) + BUG_ON(!create_worker(pool)); + + for_each_online_cpu(cpu) { + for_each_cpu_worker_pool(pool, cpu) { + pool->flags &= ~POOL_DISASSOCIATED; + BUG_ON(!create_worker(pool)); + } + } + + hash_for_each(unbound_pool_hash, bkt, pool, hash_node) + BUG_ON(!create_worker(pool)); + + wq_online = true; + wq_watchdog_init(); +} + +/* + * Initialize @pt by first initializing @pt->cpu_pod[] with pod IDs according to + * @cpu_shares_pod(). Each subset of CPUs that share a pod is assigned a unique + * and consecutive pod ID. The rest of @pt is initialized accordingly. + */ +static void __init init_pod_type(struct wq_pod_type *pt, + bool (*cpus_share_pod)(int, int)) +{ + int cur, pre, cpu, pod; + + pt->nr_pods = 0; + + /* init @pt->cpu_pod[] according to @cpus_share_pod() */ + pt->cpu_pod = kcalloc(nr_cpu_ids, sizeof(pt->cpu_pod[0]), GFP_KERNEL); + BUG_ON(!pt->cpu_pod); + + for_each_possible_cpu(cur) { + for_each_possible_cpu(pre) { + if (pre >= cur) { + pt->cpu_pod[cur] = pt->nr_pods++; + break; + } + if (cpus_share_pod(cur, pre)) { + pt->cpu_pod[cur] = pt->cpu_pod[pre]; + break; + } + } + } + + /* init the rest to match @pt->cpu_pod[] */ + pt->pod_cpus = kcalloc(pt->nr_pods, sizeof(pt->pod_cpus[0]), GFP_KERNEL); + pt->pod_node = kcalloc(pt->nr_pods, sizeof(pt->pod_node[0]), GFP_KERNEL); + BUG_ON(!pt->pod_cpus || !pt->pod_node); + + for (pod = 0; pod < pt->nr_pods; pod++) + BUG_ON(!zalloc_cpumask_var(&pt->pod_cpus[pod], GFP_KERNEL)); + + for_each_possible_cpu(cpu) { + cpumask_set_cpu(cpu, pt->pod_cpus[pt->cpu_pod[cpu]]); + pt->pod_node[pt->cpu_pod[cpu]] = cpu_to_node(cpu); + } +} + +static bool __init cpus_dont_share(int cpu0, int cpu1) +{ + return false; +} + +static bool __init cpus_share_smt(int cpu0, int cpu1) +{ +#ifdef CONFIG_SCHED_SMT + return cpumask_test_cpu(cpu0, cpu_smt_mask(cpu1)); +#else + return false; +#endif +} + +static bool __init cpus_share_numa(int cpu0, int cpu1) +{ + return cpu_to_node(cpu0) == cpu_to_node(cpu1); +} + +/** + * workqueue_init_topology - initialize CPU pods for unbound workqueues + * + * This is the third step of three-staged workqueue subsystem initialization and + * invoked after SMP and topology information are fully initialized. It + * initializes the unbound CPU pods accordingly. + */ +void __init workqueue_init_topology(void) +{ + struct workqueue_struct *wq; + int cpu; + + init_pod_type(&wq_pod_types[WQ_AFFN_CPU], cpus_dont_share); + init_pod_type(&wq_pod_types[WQ_AFFN_SMT], cpus_share_smt); + init_pod_type(&wq_pod_types[WQ_AFFN_CACHE], cpus_share_cache); + init_pod_type(&wq_pod_types[WQ_AFFN_NUMA], cpus_share_numa); + + wq_topo_initialized = true; + + mutex_lock(&wq_pool_mutex); + + /* + * Workqueues allocated earlier would have all CPUs sharing the default + * worker pool. Explicitly call unbound_wq_update_pwq() on all workqueue + * and CPU combinations to apply per-pod sharing. + */ + list_for_each_entry(wq, &workqueues, list) { + for_each_online_cpu(cpu) + unbound_wq_update_pwq(wq, cpu); + if (wq->flags & WQ_UNBOUND) { + mutex_lock(&wq->mutex); + wq_update_node_max_active(wq, -1); + mutex_unlock(&wq->mutex); + } + } + + mutex_unlock(&wq_pool_mutex); +} + +void __warn_flushing_systemwide_wq(void) +{ + pr_warn("WARNING: Flushing system-wide workqueues will be prohibited in near future.\n"); + dump_stack(); +} +EXPORT_SYMBOL(__warn_flushing_systemwide_wq); + +static int __init workqueue_unbound_cpus_setup(char *str) +{ + if (cpulist_parse(str, &wq_cmdline_cpumask) < 0) { + cpumask_clear(&wq_cmdline_cpumask); + pr_warn("workqueue.unbound_cpus: incorrect CPU range, using default\n"); + } + + return 1; } -early_initcall(init_workqueues); +__setup("workqueue.unbound_cpus=", workqueue_unbound_cpus_setup); |