From 381a4f3b38603aab47e5500609d5ec733b5d0ecb Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 8 Nov 2021 16:52:02 -0800 Subject: rcu-tasks: Use spin_lock_rcu_node() and friends This commit renames the rcu_tasks_percpu structure's ->cbs_pcpu_lock to ->lock and then uses spin_lock_rcu_node() and friends to acquire and release this lock, preparing for upcoming commits that will spread the grace-period process across multiple CPUs and kthreads. [ paulmck: Apply feedback from kernel test robot. ] Reported-by: Martin Lau Cc: Neeraj Upadhyay Signed-off-by: Paul E. McKenney --- kernel/rcu/tasks.h | 42 ++++++++++++++++++++---------------------- 1 file changed, 20 insertions(+), 22 deletions(-) (limited to 'kernel/rcu') diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index 2e58d7fa2da4..8cf325146fb0 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -23,11 +23,11 @@ typedef void (*postgp_func_t)(struct rcu_tasks *rtp); /** * struct rcu_tasks_percpu - Per-CPU component of definition for a Tasks-RCU-like mechanism. * @cblist: Callback list. - * @cbs_pcpu_lock: Lock protecting per-CPU callback list. + * @lock: Lock protecting per-CPU callback list. */ struct rcu_tasks_percpu { struct rcu_segcblist cblist; - raw_spinlock_t cbs_pcpu_lock; + raw_spinlock_t __private lock; }; /** @@ -82,7 +82,7 @@ struct rcu_tasks { #define DEFINE_RCU_TASKS(rt_name, gp, call, n) \ static DEFINE_PER_CPU(struct rcu_tasks_percpu, rt_name ## __percpu) = { \ - .cbs_pcpu_lock = __RAW_SPIN_LOCK_UNLOCKED(rt_name ## __percpu.cbs_pcpu_lock), \ + .lock = __RAW_SPIN_LOCK_UNLOCKED(rt_name ## __percpu.cbs_pcpu_lock), \ }; \ static struct rcu_tasks rt_name = \ { \ @@ -177,11 +177,11 @@ static void cblist_init_generic(struct rcu_tasks *rtp) WARN_ON_ONCE(!rtpcp); if (cpu) - raw_spin_lock_init(&rtpcp->cbs_pcpu_lock); - raw_spin_lock(&rtpcp->cbs_pcpu_lock); // irqs already disabled. + raw_spin_lock_init(&ACCESS_PRIVATE(rtpcp, lock)); + raw_spin_lock_rcu_node(rtpcp); // irqs already disabled. if (rcu_segcblist_empty(&rtpcp->cblist)) rcu_segcblist_init(&rtpcp->cblist); - raw_spin_unlock(&rtpcp->cbs_pcpu_lock); // irqs remain disabled. + raw_spin_unlock_rcu_node(rtpcp); // irqs remain disabled. } raw_spin_unlock_irqrestore(&rtp->cbs_gbl_lock, flags); @@ -200,15 +200,15 @@ static void call_rcu_tasks_generic(struct rcu_head *rhp, rcu_callback_t func, local_irq_save(flags); rtpcp = per_cpu_ptr(rtp->rtpcpu, smp_processor_id() >> READ_ONCE(rtp->percpu_enqueue_shift)); - raw_spin_lock(&rtpcp->cbs_pcpu_lock); + raw_spin_lock_rcu_node(rtpcp); // irqs already disabled. if (!rcu_segcblist_is_enabled(&rtpcp->cblist)) { - raw_spin_unlock(&rtpcp->cbs_pcpu_lock); // irqs remain disabled. + raw_spin_unlock_rcu_node(rtpcp); // irqs remain disabled. cblist_init_generic(rtp); - raw_spin_lock(&rtpcp->cbs_pcpu_lock); // irqs already disabled. + raw_spin_lock_rcu_node(rtpcp); // irqs already disabled. } needwake = rcu_segcblist_empty(&rtpcp->cblist); rcu_segcblist_enqueue(&rtpcp->cblist, rhp); - raw_spin_unlock_irqrestore(&rtpcp->cbs_pcpu_lock, flags); + raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags); /* We can't create the thread unless interrupts are enabled. */ if (needwake && READ_ONCE(rtp->kthread_ptr)) wake_up(&rtp->cbs_wq); @@ -250,11 +250,10 @@ static int __noreturn rcu_tasks_kthread(void *arg) set_tasks_gp_state(rtp, RTGS_WAIT_CBS); /* Pick up any new callbacks. */ - raw_spin_lock_irqsave(&rtpcp->cbs_pcpu_lock, flags); - smp_mb__after_spinlock(); // Order updates vs. GP. + raw_spin_lock_irqsave_rcu_node(rtpcp, flags); rcu_segcblist_advance(&rtpcp->cblist, rcu_seq_current(&rtp->tasks_gp_seq)); (void)rcu_segcblist_accelerate(&rtpcp->cblist, rcu_seq_snap(&rtp->tasks_gp_seq)); - raw_spin_unlock_irqrestore(&rtpcp->cbs_pcpu_lock, flags); + raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags); /* If there were none, wait a bit and start over. */ if (!rcu_segcblist_pend_cbs(&rtpcp->cblist)) { @@ -277,11 +276,10 @@ static int __noreturn rcu_tasks_kthread(void *arg) /* Invoke the callbacks. */ set_tasks_gp_state(rtp, RTGS_INVOKE_CBS); - raw_spin_lock_irqsave(&rtpcp->cbs_pcpu_lock, flags); - smp_mb__after_spinlock(); // Order updates vs. GP. + raw_spin_lock_irqsave_rcu_node(rtpcp, flags); rcu_segcblist_advance(&rtpcp->cblist, rcu_seq_current(&rtp->tasks_gp_seq)); rcu_segcblist_extract_done_cbs(&rtpcp->cblist, &rcl); - raw_spin_unlock_irqrestore(&rtpcp->cbs_pcpu_lock, flags); + raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags); len = rcl.len; for (rhp = rcu_cblist_dequeue(&rcl); rhp; rhp = rcu_cblist_dequeue(&rcl)) { local_bh_disable(); @@ -289,10 +287,10 @@ static int __noreturn rcu_tasks_kthread(void *arg) local_bh_enable(); cond_resched(); } - raw_spin_lock_irqsave(&rtpcp->cbs_pcpu_lock, flags); + raw_spin_lock_irqsave_rcu_node(rtpcp, flags); rcu_segcblist_add_len(&rtpcp->cblist, -len); (void)rcu_segcblist_accelerate(&rtpcp->cblist, rcu_seq_snap(&rtp->tasks_gp_seq)); - raw_spin_unlock_irqrestore(&rtpcp->cbs_pcpu_lock, flags); + raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags); /* Paranoid sleep to keep this from entering a tight loop */ schedule_timeout_idle(rtp->gp_sleep); } @@ -470,10 +468,10 @@ static void rcu_tasks_wait_gp(struct rcu_tasks *rtp) // exit_tasks_rcu_finish() functions begin and end, respectively, the SRCU // read-side critical sections waited for by rcu_tasks_postscan(). // -// Pre-grace-period update-side code is ordered before the grace via the -// ->cbs_lock and the smp_mb__after_spinlock(). Pre-grace-period read-side -// code is ordered before the grace period via synchronize_rcu() call -// in rcu_tasks_pregp_step() and by the scheduler's locks and interrupt +// Pre-grace-period update-side code is ordered before the grace +// via the raw_spin_lock.*rcu_node(). Pre-grace-period read-side code +// is ordered before the grace period via synchronize_rcu() call in +// rcu_tasks_pregp_step() and by the scheduler's locks and interrupt // disabling. /* Pre-grace-period preparation. */ -- cgit