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authorLai Jiangshan <laijs@cn.fujitsu.com>2014-05-20 17:46:31 +0800
committerTejun Heo <tj@kernel.org>2014-05-20 10:59:31 -0400
commitda028469ba173e9c634b6ecf80bb0c69c7d1024d (patch)
tree03fb68749d70240606157675161a47d9c367e213
parent3347fc9f36e7e5d3ebe504fc4034745b5d8971d3 (diff)
workqueue: separate iteration role from worker_idr
worker_idr has the iteration (iterating for attached workers) and worker ID duties. These two duties don't have to be tied together. We can separate them and use a list for tracking attached workers and iteration. Before this separation, it wasn't possible to add rescuer workers to worker_idr due to rescuer workers couldn't allocate ID dynamically because ID-allocation depends on memory-allocation, which rescuer can't depend on. After separation, we can easily add the rescuer workers to the list for iteration without any memory-allocation. It is required when we attach the rescuer worker to the pool in later patch. tj: Minor description updates. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
-rw-r--r--kernel/workqueue.c28
-rw-r--r--kernel/workqueue_internal.h2
2 files changed, 17 insertions, 13 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 938836bc6207..a6c38b717957 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -161,7 +161,8 @@ struct worker_pool {
/* 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; /* M: worker IDs and iteration */
+ struct idr worker_idr; /* M: worker IDs */
+ struct list_head workers; /* M: attached workers */
struct completion *detach_completion; /* all workers detached */
struct workqueue_attrs *attrs; /* I: worker attributes */
@@ -363,7 +364,6 @@ 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 @pool->manager_mutex.
@@ -371,8 +371,8 @@ static void copy_workqueue_attrs(struct workqueue_attrs *to,
* 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)) \
+#define for_each_pool_worker(worker, pool) \
+ list_for_each_entry((worker), &(pool)->workers, node) \
if (({ lockdep_assert_held(&pool->manager_mutex); false; })) { } \
else
@@ -1674,6 +1674,7 @@ static struct worker *alloc_worker(void)
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;
}
@@ -1696,7 +1697,8 @@ static void worker_detach_from_pool(struct worker *worker,
mutex_lock(&pool->manager_mutex);
idr_remove(&pool->worker_idr, worker->id);
- if (idr_is_empty(&pool->worker_idr))
+ list_del(&worker->node);
+ if (list_empty(&pool->workers))
detach_completion = pool->detach_completion;
mutex_unlock(&pool->manager_mutex);
@@ -1772,6 +1774,8 @@ static struct worker *create_worker(struct worker_pool *pool)
/* successful, commit the pointer to idr */
idr_replace(&pool->worker_idr, worker, worker->id);
+ /* successful, attach the worker to the pool */
+ list_add_tail(&worker->node, &pool->workers);
return worker;
@@ -3483,6 +3487,7 @@ static int init_worker_pool(struct worker_pool *pool)
mutex_init(&pool->manager_arb);
mutex_init(&pool->manager_mutex);
idr_init(&pool->worker_idr);
+ INIT_LIST_HEAD(&pool->workers);
INIT_HLIST_NODE(&pool->hash_node);
pool->refcnt = 1;
@@ -3548,7 +3553,7 @@ static void put_unbound_pool(struct worker_pool *pool)
spin_unlock_irq(&pool->lock);
mutex_lock(&pool->manager_mutex);
- if (!idr_is_empty(&pool->worker_idr))
+ if (!list_empty(&pool->workers))
pool->detach_completion = &detach_completion;
mutex_unlock(&pool->manager_mutex);
@@ -4533,7 +4538,6 @@ static void wq_unbind_fn(struct work_struct *work)
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());
@@ -4548,7 +4552,7 @@ static void wq_unbind_fn(struct work_struct *work)
* before the last CPU down must be on the cpu. After
* this, they may become diasporas.
*/
- for_each_pool_worker(worker, wi, pool)
+ for_each_pool_worker(worker, pool)
worker->flags |= WORKER_UNBOUND;
pool->flags |= POOL_DISASSOCIATED;
@@ -4594,7 +4598,6 @@ 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);
@@ -4605,13 +4608,13 @@ static void rebind_workers(struct worker_pool *pool)
* 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)
WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
pool->attrs->cpumask) < 0);
spin_lock_irq(&pool->lock);
- for_each_pool_worker(worker, wi, pool) {
+ for_each_pool_worker(worker, pool) {
unsigned int worker_flags = worker->flags;
/*
@@ -4663,7 +4666,6 @@ 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);
@@ -4677,7 +4679,7 @@ static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu)
return;
/* 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)
WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
pool->attrs->cpumask) < 0);
}
diff --git a/kernel/workqueue_internal.h b/kernel/workqueue_internal.h
index 7e2204db0b1a..8888e0672442 100644
--- a/kernel/workqueue_internal.h
+++ b/kernel/workqueue_internal.h
@@ -37,6 +37,8 @@ struct worker {
struct task_struct *task; /* I: worker task */
struct worker_pool *pool; /* I: the associated pool */
/* L: for rescuers */
+ struct list_head node; /* M: anchored at pool->workers */
+ /* M: runs through worker->node */
unsigned long last_active; /* L: last active timestamp */
unsigned int flags; /* X: flags */