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Commit b5927605 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Tejun Heo
Browse files

workqueue: remove pwq_lock which is no longer used 



To simplify locking, the previous patches expanded wq->mutex to
protect all fields of each workqueue instance including the pwqs list
leaving pwq_lock without any user.  Remove the unused pwq_lock.

tj: Rebased on top of the current dev branch.  Updated description.

Signed-off-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent a357fc03

kernel/workqueue.c

+2 −11
Original line number Diff line number Diff line
@@ -125,12 +125,9 @@ enum { 
 *

 * PR: wq_pool_mutex protected for writes.  Sched-RCU protected for reads.

 *

 * PW: pwq_lock protected.

 *

 * WQ: wq->mutex protected.

 *

 * WR: wq->mutex and pwq_lock protected for writes.  Sched-RCU protected

 *     for reads.

 * WR: wq->mutex protected for writes.  Sched-RCU protected for reads.

 *

 * MD: wq_mayday_lock protected.

 */
@@ -257,7 +254,6 @@ struct workqueue_struct { 
static struct kmem_cache *pwq_cache;



static DEFINE_MUTEX(wq_pool_mutex);	/* protects pools and workqueues list */

static DEFINE_SPINLOCK(pwq_lock);	/* protects pool_workqueues */

static DEFINE_SPINLOCK(wq_mayday_lock);	/* protects wq->maydays list */



static LIST_HEAD(workqueues);		/* PL: list of all workqueues */
@@ -300,8 +296,7 @@ static void copy_workqueue_attrs(struct workqueue_attrs *to, 


#define assert_rcu_or_wq_mutex(wq)					\

	rcu_lockdep_assert(rcu_read_lock_sched_held() ||		\

			   lockdep_is_held(&wq->mutex) ||		\

			   lockdep_is_held(&pwq_lock),			\

			   lockdep_is_held(&wq->mutex),			\

			   "sched RCU or wq->mutex should be held")



#ifdef CONFIG_LOCKDEP
@@ -3549,9 +3544,7 @@ static void pwq_unbound_release_workfn(struct work_struct *work) 
	 * and consistent with the linking path.

	 */

	mutex_lock(&wq->mutex);

	spin_lock_irq(&pwq_lock);

	list_del_rcu(&pwq->pwqs_node);

	spin_unlock_irq(&pwq_lock);

	mutex_unlock(&wq->mutex);



	put_unbound_pool(pool);
@@ -3635,9 +3628,7 @@ static void init_and_link_pwq(struct pool_workqueue *pwq, 
	pwq_adjust_max_active(pwq);



	/* link in @pwq */

	spin_lock_irq(&pwq_lock);

	list_add_rcu(&pwq->pwqs_node, &wq->pwqs);

	spin_unlock_irq(&pwq_lock);



	mutex_unlock(&wq->mutex);

}