Messages in this thread Patch in this message | | | From | Willy Tarreau <> | Date | Sat, 11 Aug 2007 21:48:02 +0200 | Subject | [2.6.20.16 review 10/28] rt-mutex: Fix stale return value |
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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 woken up path.
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> --- kernel/rtmutex.c | 11 +++++++++-- 1 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c index 4ab17da..9b08847 100644 --- a/kernel/rtmutex.c +++ b/kernel/rtmutex.c @@ -659,9 +659,16 @@ 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; } -- 1.5.2.4 -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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