rtmutex: Plug preempt count leak in rt_mutex_futex_unlock() (def34eaa) · Commits · 戴 / test

mark_wakeup_next_waiter() already disables preemption, doing so again leaves us with an unpaired preempt_disable(). Fixes: ("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>

kernel/locking/rtmutex.c

+5 −5

Original line number	Diff line number	Diff line
		@@ -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() */
		}

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