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workqueue: protect wq->saved_max_active with wq->mutex

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We're expanding wq->mutex to cover all fields specific to each
workqueue with the end goal of replacing pwq_lock which will make
locking simpler and easier to understand.

This patch makes wq->saved_max_active protected by wq->mutex instead
of pwq_lock.  As pwq_lock locking around pwq_adjust_mac_active() is no
longer necessary, this patch also replaces pwq_lock lockings of
for_each_pwq() around pwq_adjust_max_active() to wq->mutex.

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 b09f4fd39c
commit a357fc0326
1 changed files with 16 additions and 17 deletions
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33
kernel/workqueue.c
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@ -243,7 +243,7 @@ struct workqueue_struct {
struct worker *rescuer; /* I: rescue worker */
int nr_drainers; /* WQ: drain in progress */
int saved_max_active; /* PW: saved pwq max_active */
int saved_max_active; /* WQ: saved pwq max_active */
#ifdef CONFIG_SYSFS
struct wq_device *wq_dev; /* I: for sysfs interface */
@ -3579,13 +3579,13 @@ static void pwq_adjust_max_active(struct pool_workqueue *pwq)
bool freezable = wq->flags & WQ_FREEZABLE;
/* for @wq->saved_max_active */
lockdep_assert_held(&pwq_lock);
lockdep_assert_held(&wq->mutex);
/* fast exit for non-freezable wqs */
if (!freezable && pwq->max_active == wq->saved_max_active)
return;
spin_lock(&pwq->pool->lock);
spin_lock_irq(&pwq->pool->lock);
if (!freezable || !(pwq->pool->flags & POOL_FREEZING)) {
pwq->max_active = wq->saved_max_active;
@ -3603,7 +3603,7 @@ static void pwq_adjust_max_active(struct pool_workqueue *pwq)
pwq->max_active = 0;
}
spin_unlock(&pwq->pool->lock);
spin_unlock_irq(&pwq->pool->lock);
}
static void init_and_link_pwq(struct pool_workqueue *pwq,
@ -3622,7 +3622,6 @@ static void init_and_link_pwq(struct pool_workqueue *pwq,
INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn);
mutex_lock(&wq->mutex);
spin_lock_irq(&pwq_lock);
/*
* Set the matching work_color. This is synchronized with
@ -3636,9 +3635,10 @@ 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);
}
@ -3803,10 +3803,10 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
*/
mutex_lock(&wq_pool_mutex);
spin_lock_irq(&pwq_lock);
mutex_lock(&wq->mutex);
for_each_pwq(pwq, wq)
pwq_adjust_max_active(pwq);
spin_unlock_irq(&pwq_lock);
mutex_unlock(&wq->mutex);
list_add(&wq->list, &workqueues);
@ -3917,14 +3917,14 @@ void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
spin_lock_irq(&pwq_lock);
mutex_lock(&wq->mutex);
wq->saved_max_active = max_active;
for_each_pwq(pwq, wq)
pwq_adjust_max_active(pwq);
spin_unlock_irq(&pwq_lock);
mutex_unlock(&wq->mutex);
}
EXPORT_SYMBOL_GPL(workqueue_set_max_active);
@ -4287,7 +4287,7 @@ EXPORT_SYMBOL_GPL(work_on_cpu);
* pool->worklist.
*
* CONTEXT:
* Grabs and releases wq_pool_mutex, pwq_lock and pool->lock's.
* Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
*/
void freeze_workqueues_begin(void)
{
@ -4309,13 +4309,12 @@ void freeze_workqueues_begin(void)
spin_unlock_irq(&pool->lock);
}
/* suppress further executions by setting max_active to zero */
spin_lock_irq(&pwq_lock);
list_for_each_entry(wq, &workqueues, list) {
mutex_lock(&wq->mutex);
for_each_pwq(pwq, wq)
pwq_adjust_max_active(pwq);
mutex_unlock(&wq->mutex);
}
spin_unlock_irq(&pwq_lock);
mutex_unlock(&wq_pool_mutex);
}
@ -4373,7 +4372,7 @@ out_unlock:
* frozen works are transferred to their respective pool worklists.
*
* CONTEXT:
* Grabs and releases wq_pool_mutex, pwq_lock and pool->lock's.
* Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
*/
void thaw_workqueues(void)
{
@ -4396,12 +4395,12 @@ void thaw_workqueues(void)
}
/* restore max_active and repopulate worklist */
spin_lock_irq(&pwq_lock);
list_for_each_entry(wq, &workqueues, list) {
mutex_lock(&wq->mutex);
for_each_pwq(pwq, wq)
pwq_adjust_max_active(pwq);
mutex_unlock(&wq->mutex);
}
spin_unlock_irq(&pwq_lock);
workqueue_freezing = false;
out_unlock: