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>

1 files changed, 6 insertions, 6 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index d448edae3513..3ac2c4d85607 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -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);