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authorWaiman Long <longman@redhat.com>2018-10-02 16:19:18 -0400
committerIngo Molnar <mingo@kernel.org>2018-10-03 08:46:03 +0200
commitce52a18db45842f5b992851a552bd7f6acb2241b (patch)
treed4a2faed3b80b59485c8621bec27ed43432d7475 /kernel/locking
parent8ee10862476ef8b9e81e5b521205fd5c620b4ffb (diff)
downloadlinux-ce52a18db45842f5b992851a552bd7f6acb2241b.tar.bz2
locking/lockdep: Add a faster path in __lock_release()
When __lock_release() is called, the most likely unlock scenario is on the innermost lock in the chain. In this case, we can skip some of the checks and provide a faster path to completion. 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/1538511560-10090-4-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.c17
1 files changed, 14 insertions, 3 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index a5d7db558928..511d30f88bce 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3626,6 +3626,13 @@ __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
curr->lockdep_depth = i;
curr->curr_chain_key = hlock->prev_chain_key;
+ /*
+ * The most likely case is when the unlock is on the innermost
+ * lock. In this case, we are done!
+ */
+ if (i == depth-1)
+ return 1;
+
if (reacquire_held_locks(curr, depth, i + 1))
return 0;
@@ -3633,10 +3640,14 @@ __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
* We had N bottles of beer on the wall, we drank one, but now
* there's not N-1 bottles of beer left on the wall...
*/
- if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
- return 0;
+ DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth-1);
- return 1;
+ /*
+ * Since reacquire_held_locks() would have called check_chain_key()
+ * indirectly via __lock_acquire(), we don't need to do it again
+ * on return.
+ */
+ return 0;
}
static int __lock_is_held(const struct lockdep_map *lock, int read)