[PATCH 2.6.32 21/42] sched/core: Remove false-positive warning from wake_up_process()

From: Willy Tarreau
Date: Sat Jan 23 2016 - 09:47:52 EST

2.6.32-longterm review patch. If anyone has any objections, please let me know.


From: Sasha Levin <sasha.levin@xxxxxxxxxx>

commit 119d6f6a3be8b424b200dcee56e74484d5445f7e upstream.

Because wakeups can (fundamentally) be late, a task might not be in
the expected state. Therefore testing against a task's state is racy,
and can yield false positives.

Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: oleg@xxxxxxxxxx
Fixes: 9067ac85d533 ("wake_up_process() should be never used to wakeup a TASK_STOPPED/TRACED task")
Link: http://lkml.kernel.org/r/1448933660-23082-1-git-send-email-sasha.levin@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
(cherry picked from commit 0e796c1b57fdd97fc040b0b78ff7fea6c0a4a39d)
Signed-off-by: Willy Tarreau <w@xxxxxx>
kernel/sched.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 42bf6a6..fe26b86 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2618,7 +2618,6 @@ out:
int wake_up_process(struct task_struct *p)
- WARN_ON(task_is_stopped_or_traced(p));
return try_to_wake_up(p, TASK_NORMAL, 0);