linux-kernel - [PATCH] kernel/rtmutex: only warn once on a try lock from bad context

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Date:	Fri, 27 May 2016 15:47:18 +0200
From:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:	linux-kernel@...r.kernel.org
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>, tglx@...utronix.de,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH] kernel/rtmutex: only warn once on a try lock from bad context

One warning should be enough to get one motivated to fix this. It is
possible that this happens more than once and so starts flooding the
output. Later the prints will be suppressed so we only get half of it.
Depending on the console system used it might not be helpfull.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 kernel/locking/rtmutex.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 3e746607abe5..1ec0f48962b3 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1478,7 +1478,7 @@ EXPORT_SYMBOL_GPL(rt_mutex_timed_lock);
  */
 int __sched rt_mutex_trylock(struct rt_mutex *lock)
 {
-	if (WARN_ON(in_irq() || in_nmi() || in_serving_softirq()))
+	if (WARN_ON_ONCE(in_irq() || in_nmi() || in_serving_softirq()))
 		return 0;
 
 	return rt_mutex_fasttrylock(lock, rt_mutex_slowtrylock);
-- 
2.8.1