[PATCH resend v4 3/5] locking/rwsem: Don't wake up one's own task

[Waiman Long]

As rwsem_down_read_failed() will queue itself and potentially call
__rwsem_do_wake(sem, RWSEM_WAKE_ANY), it is possible that a reader
will try to wake up its own task. This patch adds a check to make
sure that this won't happen.

Signed-off-by: Waiman Long <Waiman.Long@xxxxxxx>
Reviewed-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
---
 kernel/locking/rwsem-xadd.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
index c278f5a..007814f 100644
--- a/kernel/locking/rwsem-xadd.c
+++ b/kernel/locking/rwsem-xadd.c
@@ -202,7 +202,8 @@ __rwsem_do_wake(struct rw_semaphore *sem, enum rwsem_wake_type wake_type)
 		 */
 		smp_mb();
 		waiter->task = NULL;
-		wake_up_process(tsk);
+		if (likely(tsk != current))
+			wake_up_process(tsk);
 		put_task_struct(tsk);
 	} while (--loop);
 
-- 
1.7.1