locking/lockdep: Eliminate redundant IRQs check in __lock_acquire() (8ee10862) · Commits · 戴 / test

The static __lock_acquire() function has only two callers: 1) lock_acquire() 2) reacquire_held_locks() In lock_acquire(), raw_local_irq_save() is called beforehand. So IRQs must have been disabled. So the check: DEBUG_LOCKS_WARN_ON(!irqs_disabled()) is kind of redundant in this case. So move the above check to reacquire_held_locks() to eliminate redundant code in the lock_acquire() path. Signed-off-by:

Waiman Long <longman@redhat.com> Acked-by:

Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Link: http://lkml.kernel.org/r/1538511560-10090-3-git-send-email-longman@redhat.com Signed-off-by:

Ingo Molnar <mingo@kernel.org>

kernel/locking/lockdep.c

+7 −8

Original line number	Diff line number	Diff line
		@@ -3193,6 +3193,10 @@ static int __lock_is_held(const struct lockdep_map *lock, int read);
		/*
		* This gets called for every mutex_lock()/spin_lock() operation.
		* We maintain the dependency maps and validate the locking attempt:
		*
		* The callers must make sure that IRQs are disabled before calling it,
		* otherwise we could get an interrupt which would want to take locks,
		* which would end up in lockdep again.
		*/
		static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
		int trylock, int read, int check, int hardirqs_off,
		@@ -3210,14 +3214,6 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
		if (unlikely(!debug_locks))
		return 0;

		/*
		* Lockdep should run with IRQs disabled, otherwise we could
		* get an interrupt which would want to take locks, which would
		* end up in lockdep and have you got a head-ache already?
		*/
		if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return 0;

		if (!prove_locking \|\| lock->key == &__lockdep_no_validate__)
		check = 0;

		@@ -3474,6 +3470,9 @@ static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
		{
		struct held_lock *hlock;

		if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return 0;

		for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
		if (!__lock_acquire(hlock->instance,
		hlock_class(hlock)->subclass,

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