From: Sebastian Andrzej Siewior Date: Wed, 2 Dec 2015 11:34:07 +0100 Subject: [PATCH 127/354] rtmutex: trylock is okay on -RT Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=1d31366fb82713fa3ddb743d9471fb4efdebc49d non-RT kernel could deadlock on rt_mutex_trylock() in softirq context. On -RT we don't run softirqs in IRQ context but in thread context so it is not a issue here. Signed-off-by: Sebastian Andrzej Siewior --- kernel/locking/rtmutex.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index a5ec4f68527e..4bec24dfafc6 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -1583,7 +1583,11 @@ int __sched rt_mutex_trylock(struct rt_mutex *lock) { int ret; +#ifdef CONFIG_PREEMPT_RT_FULL + if (WARN_ON_ONCE(in_irq() || in_nmi())) +#else if (WARN_ON_ONCE(in_irq() || in_nmi() || in_serving_softirq())) +#endif return 0; ret = rt_mutex_fasttrylock(lock, rt_mutex_slowtrylock);