locking/rtmutex: Only warn once on a trylock from bad context

Sebastian Andrzej Siewior · Ingo Molnar · commit a461d58792d4 · 2016-06-08T14:22:00.000+02:00
One warning should be enough to get one motivated to fix this. It is possible that this happens more than once and that 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 helpful. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1464356838-1755-1-git-send-email-bigeasy@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git 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);

Original file line number	Diff line number	Diff line change
`@@ -1478,7 +1478,7 @@ EXPORT_SYMBOL_GPL(rt_mutex_timed_lock);`
`1478`	`1478`	`*/`
`1479`	`1479`	`int __sched rt_mutex_trylock(struct rt_mutex *lock)`
`1480`	`1480`	`{`
`1481`		`- if (WARN_ON(in_irq() \|\| in_nmi() \|\| in_serving_softirq()))`
	`1481`	`+ if (WARN_ON_ONCE(in_irq() \|\| in_nmi() \|\| in_serving_softirq()))`
`1482`	`1482`	`return 0;`
`1483`	`1483`
`1484`	`1484`	`return rt_mutex_fasttrylock(lock, rt_mutex_slowtrylock);`