From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932530AbdJXMu7 (ORCPT ); Tue, 24 Oct 2017 08:50:59 -0400 Received: from terminus.zytor.com ([65.50.211.136]:49341 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932273AbdJXMuz (ORCPT ); Tue, 24 Oct 2017 08:50:55 -0400 Date: Tue, 24 Oct 2017 05:46:34 -0700 From: tip-bot for Will Deacon Message-ID: Cc: peterz@infradead.org, linux-kernel@vger.kernel.org, hpa@zytor.com, torvalds@linux-foundation.org, will.deacon@arm.com, paulmck@linux.vnet.ibm.com, mingo@kernel.org, tglx@linutronix.de Reply-To: torvalds@linux-foundation.org, hpa@zytor.com, linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com, mingo@kernel.org, will.deacon@arm.com, tglx@linutronix.de, peterz@infradead.org In-Reply-To: <1508840570-22169-3-git-send-email-will.deacon@arm.com> References: <1508840570-22169-3-git-send-email-will.deacon@arm.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:locking/core] locking/barriers: Add implicit smp_read_barrier_depends() to READ_ONCE() Git-Commit-ID: 76ebbe78f7390aee075a7f3768af197ded1bdfbb 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: 76ebbe78f7390aee075a7f3768af197ded1bdfbb Gitweb: https://git.kernel.org/tip/76ebbe78f7390aee075a7f3768af197ded1bdfbb Author: Will Deacon AuthorDate: Tue, 24 Oct 2017 11:22:47 +0100 Committer: Ingo Molnar CommitDate: Tue, 24 Oct 2017 13:17:32 +0200 locking/barriers: Add implicit smp_read_barrier_depends() to READ_ONCE() In preparation for the removal of lockless_dereference(), which is the same as READ_ONCE() on all architectures other than Alpha, add an implicit smp_read_barrier_depends() to READ_ONCE() so that it can be used to head dependency chains on all architectures. Signed-off-by: Will Deacon Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1508840570-22169-3-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar --- include/linux/compiler.h | 1 + 1 file changed, 1 insertion(+) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 0808318..7d7b77d 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -242,6 +242,7 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s __read_once_size(&(x), __u.__c, sizeof(x)); \ else \ __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ + smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \ __u.__val; \ }) #define READ_ONCE(x) __READ_ONCE(x, 1)