patches/0134-sched-ttwu-Return-success-when-only-changing-the-sav.patch

From 0d4a429d52990d79c406cd314392abc6552005bd Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 13 Dec 2011 21:42:19 +0100
Subject: [PATCH 134/270] sched: ttwu: Return success when only changing the
 saved_state value

When a task blocks on a rt lock, it saves the current state in
p->saved_state, so a lock related wake up will not destroy the
original state.

When a real wakeup happens, while the task is running due to a lock
wakeup already, we update p->saved_state to TASK_RUNNING, but we do
not return success, which might cause another wakeup in the waitqueue
code and the task remains in the waitqueue list. Return success in
that case as well.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable-rt@vger.kernel.org
---
 kernel/sched/core.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2507257..fc38afc 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1593,8 +1593,10 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
 		 * if the wakeup condition is true.
 		 */
 		if (!(wake_flags & WF_LOCK_SLEEPER)) {
-			if (p->saved_state & state)
+			if (p->saved_state & state) {
 				p->saved_state = TASK_RUNNING;
+				success = 1;
+			}
 		}
 		goto out;
 	}
-- 
1.7.10.4