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 <[email protected]> --- kernel/locking/lockdep.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index add0468..ca002c0 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3625,6 +3625,13 @@ static int __lock_downgrade(struct lockdep_map *lock, 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; @@ -3632,10 +3639,14 @@ static int __lock_downgrade(struct lockdep_map *lock, 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) -- 1.8.3.1
