The following commit has been merged into the locking/urgent branch of tip: Commit-ID: c571b72e2b845ca0519670cb7c4b5fe5f56498a5 Gitweb: https://git.kernel.org/tip/c571b72e2b845ca0519670cb7c4b5fe5f56498a5 Author: Davidlohr Bueso <dave@xxxxxxxxxxxx> AuthorDate: Tue, 10 Dec 2019 14:05:23 -08:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Wed, 11 Dec 2019 00:27:43 +01:00 Revert "locking/mutex: Complain upon mutex API misuse in IRQ contexts" This ended up causing some noise in places such as rxrpc running in softirq. The warning is misleading in this case as the mutex trylock and unlock operations are done within the same context; and therefore we need not worry about the PI-boosting issues that comes along with no single-owner lock guarantees. While we don't want to support this in mutexes, there is no way out of this yet; so lets get rid of the WARNs for now, as it is only fair to code that has historically relied on non-preemptible softirq guarantees. In addition, changing the lock type is also unviable: exclusive rwsems have the same issue (just not the WARN_ON) and counting semaphores would introduce a performance hit as mutexes are a lot more optimized. This reverts: a0855d24fc22: ("locking/mutex: Complain upon mutex API misuse in IRQ contexts") Fixes: a0855d24fc22: ("locking/mutex: Complain upon mutex API misuse in IRQ contexts") Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx> Tested-by: David Howells <dhowells@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: linux-afs@xxxxxxxxxxxxxxxxxxx Cc: linux-fsdevel@xxxxxxxxxxxxxxx Cc: will@xxxxxxxxxx Link: https://lkml.kernel.org/r/20191210220523.28540-1-dave@xxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- kernel/locking/mutex.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index 54cc5f9..5352ce5 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -733,9 +733,6 @@ 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; @@ -1416,7 +1413,6 @@ 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);
