Messages in this thread Patch in this message | | | From | Waiman Long <> | Subject | [RFC PATCH-tip v2 1/6] locking/osq: Make lock/unlock proper acquire/release barrier | Date | Tue, 14 Jun 2016 18:48:04 -0400 |
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The osq_lock() and osq_unlock() function may not provide the necessary acquire and release barrier in some cases. This patch makes sure that the proper barriers are provided when osq_lock() is successful or when osq_unlock() is called.
Signed-off-by: Waiman Long <Waiman.Long@hpe.com> --- kernel/locking/osq_lock.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/locking/osq_lock.c b/kernel/locking/osq_lock.c index 05a3785..7dd4ee5 100644 --- a/kernel/locking/osq_lock.c +++ b/kernel/locking/osq_lock.c @@ -115,7 +115,7 @@ bool osq_lock(struct optimistic_spin_queue *lock) * cmpxchg in an attempt to undo our queueing. */ - while (!READ_ONCE(node->locked)) { + while (!smp_load_acquire(&node->locked)) { /* * If we need to reschedule bail... so we can block. */ @@ -198,7 +198,7 @@ void osq_unlock(struct optimistic_spin_queue *lock) * Second most likely case. */ node = this_cpu_ptr(&osq_node); - next = xchg(&node->next, NULL); + next = xchg_release(&node->next, NULL); if (next) { WRITE_ONCE(next->locked, 1); return; -- 1.7.1
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