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workqueue: remove pwq_lock which is no longer used

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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: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Lai Jiangshan 2013-03-25 16:57:19 -07:00 committed by Tejun Heo
parent a357fc0326
commit b592760547
1 changed files with 2 additions and 11 deletions
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13
kernel/workqueue.c
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@ -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);
}