[PATCH RT] locking/rtmutex: don't drop the wait_lock twice

From: Sebastian Andrzej Siewior
Date: Thu Sep 21 2017 - 11:48:50 EST


Since the futex rework, __rt_mutex_start_proxy_lock() does no longer
acquire the wait_lock so it must not drop it. Otherwise the lock is not
only unlocked twice but also the preemption counter is underflown.

Cc: rt-stable@xxxxxxxxxxxxxxx
Reported-by: Gusenleitner Klaus <gus@xxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
kernel/locking/rtmutex.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index f03876322d4a..79f49d73e4d0 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -2281,7 +2281,6 @@ int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
raw_spin_lock(&task->pi_lock);
if (task->pi_blocked_on) {
raw_spin_unlock(&task->pi_lock);
- raw_spin_unlock_irq(&lock->wait_lock);
return -EAGAIN;
}
task->pi_blocked_on = PI_REQUEUE_INPROGRESS;
--
2.14.1