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workqueue: protect wq->nr_drainers and ->flags 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.

wq->nr_drainers and ->flags are specific to each workqueue.  Protect
->nr_drainers and ->flags with wq->mutex instead of pool_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 16:57:18 -07:00 committed by Tejun Heo
parent 3c25a55daa
commit 87fc741e94
1 changed files with 6 additions and 6 deletions
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12
kernel/workqueue.c
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@ -226,7 +226,7 @@ struct wq_device;
* the appropriate worker_pool through its pool_workqueues.
*/
struct workqueue_struct {
unsigned int flags; /* PL: WQ_* flags */
unsigned int flags; /* WQ: WQ_* flags */
struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwq's */
struct list_head pwqs; /* WR: all pwqs of this wq */
struct list_head list; /* PL: list of all workqueues */
@ -242,7 +242,7 @@ struct workqueue_struct {
struct list_head maydays; /* MD: pwqs requesting rescue */
struct worker *rescuer; /* I: rescue worker */
int nr_drainers; /* PL: drain in progress */
int nr_drainers; /* WQ: drain in progress */
int saved_max_active; /* PW: saved pwq max_active */
#ifdef CONFIG_SYSFS
@ -2684,10 +2684,10 @@ void drain_workqueue(struct workqueue_struct *wq)
* hotter than drain_workqueue() and already looks at @wq->flags.
* Use __WQ_DRAINING so that queue doesn't have to check nr_drainers.
*/
mutex_lock(&wq_pool_mutex);
mutex_lock(&wq->mutex);
if (!wq->nr_drainers++)
wq->flags |= __WQ_DRAINING;
mutex_unlock(&wq_pool_mutex);
mutex_unlock(&wq->mutex);
reflush:
flush_workqueue(wq);
@ -2714,10 +2714,10 @@ reflush:
local_irq_enable();
mutex_lock(&wq_pool_mutex);
mutex_lock(&wq->mutex);
if (!--wq->nr_drainers)
wq->flags &= ~__WQ_DRAINING;
mutex_unlock(&wq_pool_mutex);
mutex_unlock(&wq->mutex);
}
EXPORT_SYMBOL_GPL(drain_workqueue);