diff options
| author | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2016-01-20 14:01:31 -0300 |
|---|---|---|
| committer | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2016-01-20 14:01:31 -0300 |
| commit | b4b7ff4b08e691656c9d77c758fc355833128ac0 (patch) | |
| tree | 82fcb00e6b918026dc9f2d1f05ed8eee83874cc0 /kernel/locking/osq_lock.c | |
| parent | 35acfa0fc609f2a2cd95cef4a6a9c3a5c38f1778 (diff) | |
Linux-libre 4.4-gnupck-4.4-gnu
Diffstat (limited to 'kernel/locking/osq_lock.c')
| -rw-r--r-- | kernel/locking/osq_lock.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/kernel/locking/osq_lock.c b/kernel/locking/osq_lock.c index dc85ee23a..05a37857a 100644 --- a/kernel/locking/osq_lock.c +++ b/kernel/locking/osq_lock.c @@ -50,7 +50,7 @@ osq_wait_next(struct optimistic_spin_queue *lock, for (;;) { if (atomic_read(&lock->tail) == curr && - atomic_cmpxchg(&lock->tail, curr, old) == curr) { + atomic_cmpxchg_acquire(&lock->tail, curr, old) == curr) { /* * We were the last queued, we moved @lock back. @prev * will now observe @lock and will complete its @@ -92,6 +92,12 @@ bool osq_lock(struct optimistic_spin_queue *lock) node->next = NULL; node->cpu = curr; + /* + * We need both ACQUIRE (pairs with corresponding RELEASE in + * unlock() uncontended, or fastpath) and RELEASE (to publish + * the node fields we just initialised) semantics when updating + * the lock tail. + */ old = atomic_xchg(&lock->tail, curr); if (old == OSQ_UNLOCKED_VAL) return true; @@ -184,7 +190,8 @@ void osq_unlock(struct optimistic_spin_queue *lock) /* * Fast path for the uncontended case. */ - if (likely(atomic_cmpxchg(&lock->tail, curr, OSQ_UNLOCKED_VAL) == curr)) + if (likely(atomic_cmpxchg_release(&lock->tail, curr, + OSQ_UNLOCKED_VAL) == curr)) return; /* |