From 50f8ea4c311b4bc5100595c2c43f02754afa2798 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Wed, 2 Dec 2015 11:34:07 +0100 Subject: [PATCH 076/191] locking/rtmutex: Allow rt_mutex_trylock() on PREEMPT_RT Non PREEMPT_RT kernel can deadlock on rt_mutex_trylock() in softirq context. On PREEMPT_RT the softirq context is handled in thread context. This avoids the deadlock in the slow path and PI-boosting will be done on the correct thread. 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 03ffb955b286..f0bc7fcae441 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -1866,7 +1866,11 @@ int __sched __rt_mutex_futex_trylock(struct rt_mutex *lock) int __sched __rt_mutex_trylock(struct rt_mutex *lock) { +#ifdef CONFIG_PREEMPT_RT + if (WARN_ON_ONCE(in_irq() || in_nmi())) +#else if (WARN_ON_ONCE(in_irq() || in_nmi() || in_serving_softirq())) +#endif return 0; return rt_mutex_fasttrylock(lock, rt_mutex_slowtrylock); -- 2.19.1