diff options
| author | Waiman Long <longman@redhat.com> | 2018-10-02 16:19:17 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-10-03 08:46:02 +0200 |
| commit | 8ee10862476ef8b9e81e5b521205fd5c620b4ffb (patch) | |
| tree | 1a84b111fdc5b1ce298da14c4b951be6e377f534 /kernel/locking | |
| parent | 44318d5b07be7d7cfe718aa22ea3b2577361a0b5 (diff) | |
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>
Diffstat (limited to 'kernel/locking')
| -rw-r--r-- | kernel/locking/lockdep.c | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index fa82d55279fe..a5d7db558928 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -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, |