workqueue: fix locking in retry path of maybe_create_worker()

maybe_create_worker() mismanaged locking when worker creation fails
and it has to retry.  Fix locking and simplify lock manipulation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Yong Zhang <yong.zhang@windriver.com>

1 files changed, 3 insertions, 5 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 20d6237d749..aca94726e20 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1442,14 +1442,14 @@ static bool maybe_create_worker(struct global_cwq *gcwq)
         if (!need_to_create_worker(gcwq))
                 return false;
 restart:
+        spin_unlock_irq(&gcwq->lock);
+
         /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
         mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
 
         while (true) {
                 struct worker *worker;
 
-                spin_unlock_irq(&gcwq->lock);
-
                 worker = create_worker(gcwq, true);
                 if (worker) {
                         del_timer_sync(&gcwq->mayday_timer);
@@ -1462,15 +1462,13 @@ restart:
                 if (!need_to_create_worker(gcwq))
                         break;
 
-                spin_unlock_irq(&gcwq->lock);
                 __set_current_state(TASK_INTERRUPTIBLE);
                 schedule_timeout(CREATE_COOLDOWN);
-                spin_lock_irq(&gcwq->lock);
+
                 if (!need_to_create_worker(gcwq))
                         break;
         }
 
-        spin_unlock_irq(&gcwq->lock);
         del_timer_sync(&gcwq->mayday_timer);
         spin_lock_irq(&gcwq->lock);
         if (need_to_create_worker(gcwq))