workqueue: protect wq->saved_max_active with wq->mutex
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>
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 9c32fd1..af6087a 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -243,7 +243,7 @@
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 @@
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 @@
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 @@
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 @@
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 @@
*/
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 @@
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 @@
* 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 @@
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 @@
* 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 @@
}
/* 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: