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 Signed-off-by: Thomas Gleixner Acked-by: Ingo Molnar Signed-off-by: Chris Wright Signed-off-by: Greg Kroah-Hartman --- 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/