Commit a0855d24 authored Oct 24, 2019 by Davidlohr Bueso Committed by Ingo Molnar Oct 29, 2019

locking/mutex: Complain upon mutex API misuse in IRQ contexts



Add warning checks if mutex_trylock() or mutex_unlock() are used in
IRQ contexts, under CONFIG_DEBUG_MUTEXES=y.

While the mutex rules and semantics are explicitly documented, this allows
to expose any abusers and robustifies the whole thing.

While trylock and unlock are non-blocking, calling from IRQ context
is still forbidden (lock must be within the same context as unlock).

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Link: https://lkml.kernel.org/r/20191025033634.3330-1-dave@stgolabs.net


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 75145904

kernel/locking/mutex.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -733,6 +733,9 @@ static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigne
		*/
		void __sched mutex_unlock(struct mutex *lock)
		{
		#ifdef CONFIG_DEBUG_MUTEXES
		WARN_ON(in_interrupt());
		#endif
		#ifndef CONFIG_DEBUG_LOCK_ALLOC
		if (__mutex_unlock_fast(lock))
		return;
		@@ -1413,6 +1416,7 @@ int __sched mutex_trylock(struct mutex *lock)

		#ifdef CONFIG_DEBUG_MUTEXES
		DEBUG_LOCKS_WARN_ON(lock->magic != lock);
		WARN_ON(in_interrupt());
		#endif

		locked = __mutex_trylock(lock);

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