workqueue: move rescuer pool detachment to the end

In 51697d393922 ("workqueue: use generic attach/detach routine for
rescuers"), The rescuer detaches itself from the pool before put_pwq()
so that the put_unbound_pool() will not destroy the rescuer-attached
pool.

It is unnecessary.  worker_detach_from_pool() can be used as the last
statement to access to the pool just like the regular workers,
put_unbound_pool() will wait for it to detach and then free the pool.

So we move the worker_detach_from_pool() down, make it coincide with
the regular workers.

tj: Minor description update.

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 4cb8527..4d9600f 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2253,15 +2253,10 @@ repeat:
                                move_linked_works(work, scheduled, &n);
 
                process_scheduled_works(rescuer);
-               spin_unlock_irq(&pool->lock);
-
-               worker_detach_from_pool(rescuer, pool);
-
-               spin_lock_irq(&pool->lock);
 
                /*
                 * Put the reference grabbed by send_mayday().  @pool won't
-                * go away while we're holding its lock.
+                * go away while we're still attached to it.
                 */
                put_pwq(pwq);
 
@@ -2274,8 +2269,11 @@ repeat:
                        wake_up_worker(pool);
 
                rescuer->pool = NULL;
-               spin_unlock(&pool->lock);
-               spin_lock(&wq_mayday_lock);
+               spin_unlock_irq(&pool->lock);
+
+               worker_detach_from_pool(rescuer, pool);
+
+               spin_lock_irq(&wq_mayday_lock);
        }
 
        spin_unlock_irq(&wq_mayday_lock);