[tip:sched/core] sched/__wake_up_sync_key(): Fix nr_exclusive tasks which lead to WF_SYNC clearing

[tip-bot for Kirill Tkhai <tipbot@zytor.com>]

Commit-ID:  cedce3e730833d26a37826a96e1905b6ef387df9
Gitweb:     http://git.kernel.org/tip/cedce3e730833d26a37826a96e1905b6ef387df9
Author:     Kirill Tkhai <tkhai@yandex.ru>
AuthorDate: Thu, 4 Jul 2013 22:48:20 +0400
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 12 Jul 2013 13:54:03 +0200

sched/__wake_up_sync_key(): Fix nr_exclusive tasks which lead to WF_SYNC clearing

Only one task can replace the waker.

Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
CC: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/512421372963700@web25f.yandex.ru
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sched/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0d8eb45..f737871 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2660,7 +2660,7 @@ void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode,
 	if (unlikely(!q))
 		return;
 
-	if (unlikely(!nr_exclusive))
+	if (unlikely(nr_exclusive != 1))
 		wake_flags = 0;
 
 	spin_lock_irqsave(&q->lock, flags);