[RFC PATCH-tip v2 1/6] locking/osq: Make lock/unlock proper acquire/release barrier
From: Waiman Long <hidden>
Date: 2016-06-14 22:48:35
Also in:
linux-arch, linux-s390, lkml
Subsystem:
locking primitives, the rest · Maintainers:
Peter Zijlstra, Ingo Molnar, Will Deacon, Boqun Feng, Linus Torvalds
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 <redacted> --- 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