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Commit b2eb83d1 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Tejun Heo
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workqueue: rename manager_mutex to assoc_mutex 



Now that manager_mutex's role has changed from synchronizing manager
role to excluding hotplug against manager, the name is misleading.

As it is protecting the CPU-association of the gcwq now, rename it to
assoc_mutex.

This patch is pure rename and doesn't introduce any functional change.

tj: Updated comments and description.

Signed-off-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 5f7dabfd

kernel/workqueue.c

+19 −19
Original line number Diff line number Diff line
@@ -58,7 +58,7 @@ enum { 
	 * be executing on any CPU.  The gcwq behaves as an unbound one.

	 *

	 * Note that DISASSOCIATED can be flipped only while holding

	 * managership of all pools on the gcwq to avoid changing binding

	 * assoc_mutex of all pools on the gcwq to avoid changing binding

	 * state while create_worker() is in progress.

	 */

	GCWQ_DISASSOCIATED	= 1 << 0,	/* cpu can't serve workers */
@@ -165,7 +165,7 @@ struct worker_pool { 
	struct timer_list	idle_timer;	/* L: worker idle timeout */

	struct timer_list	mayday_timer;	/* L: SOS timer for workers */



	struct mutex		manager_mutex;	/* mutex manager should hold */

	struct mutex		assoc_mutex;	/* protect GCWQ_DISASSOCIATED */

	struct ida		worker_ida;	/* L: for worker IDs */

};
@@ -1681,7 +1681,7 @@ static void rebind_workers(struct global_cwq *gcwq) 
	lockdep_assert_held(&gcwq->lock);



	for_each_worker_pool(pool, gcwq)

		lockdep_assert_held(&pool->manager_mutex);

		lockdep_assert_held(&pool->assoc_mutex);



	/* dequeue and kick idle ones */

	for_each_worker_pool(pool, gcwq) {
@@ -2081,22 +2081,22 @@ static bool manage_workers(struct worker *worker) 
	 * grab %POOL_MANAGING_WORKERS to achieve this because that can

	 * lead to idle worker depletion (all become busy thinking someone

	 * else is managing) which in turn can result in deadlock under

	 * extreme circumstances.  Use @pool->manager_mutex to synchronize

	 * extreme circumstances.  Use @pool->assoc_mutex to synchronize

	 * manager against CPU hotplug.

	 *

	 * manager_mutex would always be free unless CPU hotplug is in

	 * assoc_mutex would always be free unless CPU hotplug is in

	 * progress.  trylock first without dropping @gcwq->lock.

	 */

	if (unlikely(!mutex_trylock(&pool->manager_mutex))) {

	if (unlikely(!mutex_trylock(&pool->assoc_mutex))) {

		spin_unlock_irq(&pool->gcwq->lock);

		mutex_lock(&pool->manager_mutex);

		mutex_lock(&pool->assoc_mutex);

		/*

		 * CPU hotplug could have happened while we were waiting

		 * for manager_mutex.  Hotplug itself can't handle us

		 * for assoc_mutex.  Hotplug itself can't handle us

		 * because manager isn't either on idle or busy list, and

		 * @gcwq's state and ours could have deviated.

		 *

		 * As hotplug is now excluded via manager_mutex, we can

		 * As hotplug is now excluded via assoc_mutex, we can

		 * simply try to bind.  It will succeed or fail depending

		 * on @gcwq's current state.  Try it and adjust

		 * %WORKER_UNBOUND accordingly.
@@ -2119,7 +2119,7 @@ static bool manage_workers(struct worker *worker) 
	ret |= maybe_create_worker(pool);



	pool->flags &= ~POOL_MANAGING_WORKERS;

	mutex_unlock(&pool->manager_mutex);

	mutex_unlock(&pool->assoc_mutex);

	return ret;

}
@@ -3474,23 +3474,23 @@ EXPORT_SYMBOL_GPL(work_busy); 
 */



/* claim manager positions of all pools */

static void gcwq_claim_management_and_lock(struct global_cwq *gcwq)

static void gcwq_claim_assoc_and_lock(struct global_cwq *gcwq)

{

	struct worker_pool *pool;



	for_each_worker_pool(pool, gcwq)

		mutex_lock_nested(&pool->manager_mutex, pool - gcwq->pools);

		mutex_lock_nested(&pool->assoc_mutex, pool - gcwq->pools);

	spin_lock_irq(&gcwq->lock);

}



/* release manager positions */

static void gcwq_release_management_and_unlock(struct global_cwq *gcwq)

static void gcwq_release_assoc_and_unlock(struct global_cwq *gcwq)

{

	struct worker_pool *pool;



	spin_unlock_irq(&gcwq->lock);

	for_each_worker_pool(pool, gcwq)

		mutex_unlock(&pool->manager_mutex);

		mutex_unlock(&pool->assoc_mutex);

}



static void gcwq_unbind_fn(struct work_struct *work)
@@ -3503,7 +3503,7 @@ static void gcwq_unbind_fn(struct work_struct *work) 


	BUG_ON(gcwq->cpu != smp_processor_id());



	gcwq_claim_management_and_lock(gcwq);

	gcwq_claim_assoc_and_lock(gcwq);



	/*

	 * We've claimed all manager positions.  Make all workers unbound
@@ -3520,7 +3520,7 @@ static void gcwq_unbind_fn(struct work_struct *work) 


	gcwq->flags |= GCWQ_DISASSOCIATED;



	gcwq_release_management_and_unlock(gcwq);

	gcwq_release_assoc_and_unlock(gcwq);



	/*

	 * Call schedule() so that we cross rq->lock and thus can guarantee
@@ -3576,10 +3576,10 @@ static int __devinit workqueue_cpu_up_callback(struct notifier_block *nfb, 


	case CPU_DOWN_FAILED:

	case CPU_ONLINE:

		gcwq_claim_management_and_lock(gcwq);

		gcwq_claim_assoc_and_lock(gcwq);

		gcwq->flags &= ~GCWQ_DISASSOCIATED;

		rebind_workers(gcwq);

		gcwq_release_management_and_unlock(gcwq);

		gcwq_release_assoc_and_unlock(gcwq);

		break;

	}

	return NOTIFY_OK;
@@ -3833,7 +3833,7 @@ static int __init init_workqueues(void) 
			setup_timer(&pool->mayday_timer, gcwq_mayday_timeout,

				    (unsigned long)pool);



			mutex_init(&pool->manager_mutex);

			mutex_init(&pool->assoc_mutex);

			ida_init(&pool->worker_ida);

		}

	}