From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755289AbbITKM7 (ORCPT ); Sun, 20 Sep 2015 06:12:59 -0400 Received: from smtp2.provo.novell.com ([137.65.250.81]:36928 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754941AbbITKMO (ORCPT ); Sun, 20 Sep 2015 06:12:14 -0400 From: Davidlohr Bueso To: Peter Zijlstra , Ingo Molnar , Thomas Gleixner Cc: Andrew Morton , Linus Torvalds , Will Deacon , "Paul E. McKenney" , Davidlohr Bueso , linux-kernel@vger.kernel.org, Davidlohr Bueso Subject: [PATCH 5/5] locking/mcs: Relax to atomic/release semantics Date: Sun, 20 Sep 2015 03:11:51 -0700 Message-Id: <1442743911-25366-6-git-send-email-dave@stgolabs.net> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1442743911-25366-1-git-send-email-dave@stgolabs.net> References: <1442743911-25366-1-git-send-email-dave@stgolabs.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ... by using acquire semantics where appropriate As such, weakly ordered archs can benefit from more relaxed use of barriers when issuing atomics. Signed-off-by: Davidlohr Bueso --- kernel/locking/mcs_spinlock.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/locking/mcs_spinlock.h b/kernel/locking/mcs_spinlock.h index fd91aaa..5b9102a 100644 --- a/kernel/locking/mcs_spinlock.h +++ b/kernel/locking/mcs_spinlock.h @@ -67,7 +67,7 @@ void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node) node->locked = 0; node->next = NULL; - prev = xchg(lock, node); + prev = xchg_acquire(lock, node); if (likely(prev == NULL)) { /* * Lock acquired, don't need to set node->locked to 1. Threads @@ -98,7 +98,7 @@ void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node) /* * Release the lock by setting it to NULL */ - if (likely(cmpxchg(lock, node, NULL) == node)) + if (likely(cmpxchg_release(lock, node, NULL) == node)) return; /* Wait until the next pointer is set */ while (!(next = READ_ONCE(node->next))) -- 2.1.4