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locking/lockdep: Eliminate redundant IRQs check in __lock_acquire() 

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>
This commit is contained in:
Waiman Long 2018-10-02 16:19:17 -04:00 committed by Ingo Molnar
parent 44318d5b07
commit 8ee1086247
1 changed files with 7 additions and 8 deletions
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15
kernel/locking/lockdep.c
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@ -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,