Commit-ID: b193049375b04df3ada8c3347b7083db95918bc3 Gitweb: http://git.kernel.org/tip/b193049375b04df3ada8c3347b7083db95918bc3 Author: Pan Xinhui <xinhui.pan@xxxxxxxxxxxxxxxxxx> AuthorDate: Mon, 19 Sep 2016 05:23:52 -0400 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Thu, 22 Sep 2016 15:25:51 +0200 locking/pv-qspinlock: Use cmpxchg_release() in __pv_queued_spin_unlock() cmpxchg_release() is more lighweight than cmpxchg() on some archs(e.g. PPC), moreover, in __pv_queued_spin_unlock() we only needs a RELEASE in the fast path(pairing with *_try_lock() or *_lock()). And the slow path has smp_store_release too. So it's safe to use cmpxchg_release here. Suggested-by: Boqun Feng <boqun.feng@xxxxxxxxx> Signed-off-by: Pan Xinhui <xinhui.pan@xxxxxxxxxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: benh@xxxxxxxxxxxxxxxxxxx Cc: linuxppc-dev@xxxxxxxxxxxxxxxx Cc: mpe@xxxxxxxxxxxxxx Cc: paulmck@xxxxxxxxxxxxxxxxxx Cc: paulus@xxxxxxxxx Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx Cc: waiman.long@xxxxxxx Link: http://lkml.kernel.org/r/1474277037-15200-2-git-send-email-xinhui.pan@xxxxxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- kernel/locking/qspinlock_paravirt.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h index 3acf16d..e3b5520 100644 --- a/kernel/locking/qspinlock_paravirt.h +++ b/kernel/locking/qspinlock_paravirt.h @@ -540,7 +540,7 @@ __visible void __pv_queued_spin_unlock(struct qspinlock *lock) * unhash. Otherwise it would be possible to have multiple @lock * entries, which would be BAD. */ - locked = cmpxchg(&l->locked, _Q_LOCKED_VAL, 0); + locked = cmpxchg_release(&l->locked, _Q_LOCKED_VAL, 0); if (likely(locked == _Q_LOCKED_VAL)) return; -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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