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authorMike Galbraith <efault@gmx.de>2017-04-05 10:08:27 +0200
committerThomas Gleixner <tglx@linutronix.de>2017-04-05 16:59:37 +0200
commitdef34eaae5ce04b324e48e1bfac873091d945213 (patch)
treed262afbd2361a24be327fa101c445c427c3d480d /kernel/locking/rtmutex.c
parent19830e55247cddb3f46f1bf60b8e245593491bea (diff)
downloadlinux-def34eaae5ce04b324e48e1bfac873091d945213.tar.bz2
rtmutex: Plug preempt count leak in rt_mutex_futex_unlock()
mark_wakeup_next_waiter() already disables preemption, doing so again leaves us with an unpaired preempt_disable(). Fixes: 2a1c60299406 ("rtmutex: Deboost before waking up the top waiter") Signed-off-by: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: xlpang@redhat.com Cc: rostedt@goodmis.org Link: http://lkml.kernel.org/r/1491379707.6538.2.camel@gmx.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/locking/rtmutex.c')
-rw-r--r--kernel/locking/rtmutex.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 0e641eb473de..b95509416909 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1581,13 +1581,13 @@ bool __sched __rt_mutex_futex_unlock(struct rt_mutex *lock,
return false; /* done */
}
- mark_wakeup_next_waiter(wake_q, lock);
/*
- * We've already deboosted, retain preempt_disabled when dropping
- * the wait_lock to avoid inversion until the wakeup. Matched
- * by rt_mutex_postunlock();
+ * We've already deboosted, mark_wakeup_next_waiter() will
+ * retain preempt_disabled when we drop the wait_lock, to
+ * avoid inversion prior to the wakeup. preempt_disable()
+ * therein pairs with rt_mutex_postunlock().
*/
- preempt_disable();
+ mark_wakeup_next_waiter(wake_q, lock);
return true; /* call postunlock() */
}