[39/70] workqueue: wake up a worker when a rescuer is leaving a gcwq

[Greg KH]

2.6.37-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Tejun Heo <tj@xxxxxxxxxx>

commit 7576958a9d5a4a677ad7dd40901cdbb6c1110c98 upstream.

After executing the matching works, a rescuer leaves the gcwq whether
there are more pending works or not.  This may decrease the
concurrency level to zero and stall execution until a new work item is
queued on the gcwq.

Make rescuer wake up a regular worker when it leaves a gcwq if there
are more works to execute, so that execution isn't stalled.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Reported-by: Ray Jui <rjui@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 kernel/workqueue.c |    9 +++++++++
 1 file changed, 9 insertions(+)

--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2009,6 +2009,15 @@ repeat:
 				move_linked_works(work, scheduled, &n);
 
 		process_scheduled_works(rescuer);
+
+		/*
+		 * Leave this gcwq.  If keep_working() is %true, notify a
+		 * regular worker; otherwise, we end up with 0 concurrency
+		 * and stalling the execution.
+		 */
+		if (keep_working(gcwq))
+			wake_up_worker(gcwq);
+
 		spin_unlock_irq(&gcwq->lock);
 	}
 


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