From c0d1d2bf5a28f78def7b68ca1eb5ba31aafd43a1 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 8 Jun 2007 13:46:57 -0700 Subject: [PATCH] rt-mutex: fix stale return value Alexey Kuznetsov found some problems in the pi-futex code. The major problem is a stale return value in rt_mutex_slowlock(): When the pi chain walk returns -EDEADLK, but the waiter was woken up during the phases where the locks were dropped, the rtmutex could be acquired, but due to the stale return value -EDEADLK returned to the caller. Reset the return value in the retry path. Signed-off-by: Thomas Gleixner Acked-by: Ingo Molnar Cc: Steven Rostedt Cc: Alexey Kuznetsov Cc: Ulrich Drepper Cc: Eric Dumazet Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/rtmutex.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c index 12879f6c1ec3..a273183c37a0 100644 --- a/kernel/rtmutex.c +++ b/kernel/rtmutex.c @@ -636,9 +636,16 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state, * all over without going into schedule to try * to get the lock now: */ - if (unlikely(!waiter.task)) + if (unlikely(!waiter.task)) { + /* + * Reset the return value. We might + * have returned with -EDEADLK and the + * owner released the lock while we + * were walking the pi chain. + */ + ret = 0; continue; - + } if (unlikely(ret)) break; }