From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934264AbcIVODi (ORCPT ); Thu, 22 Sep 2016 10:03:38 -0400 Received: from terminus.zytor.com ([198.137.202.10]:56916 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756833AbcIVODe (ORCPT ); Thu, 22 Sep 2016 10:03:34 -0400 Date: Thu, 22 Sep 2016 07:02:46 -0700 From: tip-bot for Pan Xinhui Message-ID: Cc: torvalds@linux-foundation.org, xinhui.pan@linux.vnet.ibm.com, tglx@linutronix.de, mingo@kernel.org, hpa@zytor.com, boqun.feng@gmail.com, linux-kernel@vger.kernel.org, peterz@infradead.org Reply-To: xinhui.pan@linux.vnet.ibm.com, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, peterz@infradead.org, boqun.feng@gmail.com, mingo@kernel.org, hpa@zytor.com, tglx@linutronix.de In-Reply-To: <1474277037-15200-2-git-send-email-xinhui.pan@linux.vnet.ibm.com> References: <1474277037-15200-2-git-send-email-xinhui.pan@linux.vnet.ibm.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:locking/core] locking/pv-qspinlock: Use cmpxchg_release() in __pv_queued_spin_unlock() Git-Commit-ID: b193049375b04df3ada8c3347b7083db95918bc3 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: b193049375b04df3ada8c3347b7083db95918bc3 Gitweb: http://git.kernel.org/tip/b193049375b04df3ada8c3347b7083db95918bc3 Author: Pan Xinhui AuthorDate: Mon, 19 Sep 2016 05:23:52 -0400 Committer: Ingo Molnar 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 Signed-off-by: Pan Xinhui Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: benh@kernel.crashing.org Cc: linuxppc-dev@lists.ozlabs.org Cc: mpe@ellerman.id.au Cc: paulmck@linux.vnet.ibm.com Cc: paulus@samba.org Cc: virtualization@lists.linux-foundation.org Cc: waiman.long@hpe.com Link: http://lkml.kernel.org/r/1474277037-15200-2-git-send-email-xinhui.pan@linux.vnet.ibm.com Signed-off-by: Ingo Molnar --- 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;