From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754623AbbKWWEb (ORCPT ); Mon, 23 Nov 2015 17:04:31 -0500 Received: from mail-db3on0092.outbound.protection.outlook.com ([157.55.234.92]:63530 "EHLO emea01-db3-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752126AbbKWWE2 (ORCPT ); Mon, 23 Nov 2015 17:04:28 -0500 Authentication-Results: spf=fail (sender IP is 12.216.194.146) smtp.mailfrom=ezchip.com; ezchip.com; dkim=none (message not signed) header.d=none;ezchip.com; dmarc=none action=none header.from=ezchip.com; From: Chris Metcalf To: "Paul E. McKenney" , Jonathan Corbet , , CC: Chris Metcalf Subject: [PATCH] Documentation/memory-barriers.txt: fix ACCESS_ONCE thinko Date: Mon, 23 Nov 2015 17:04:17 -0500 Message-ID: <1448316257-18246-1-git-send-email-cmetcalf@ezchip.com> X-Mailer: git-send-email 2.1.2 X-EOPAttributedMessage: 0 X-Microsoft-Exchange-Diagnostics: 1;DB3FFO11FD008;1:SXipwsyfYlSO+Zi4VwsYLNTb8i4d26Z52y7IFXDQQOLZ8FKYrn029vtATou4lGk9n+GGR0KQVzrh9Uem269MZDx1MeESd/IwltvC1Ge8hF+HI7ZNNDSgHHV8hw0ObOvzQubvfy+gDqrJtUpSNST5akWC7s9NDc7fN5s+RjGSMPQRZflhqge0DL4M5ijwITE8K+r16NNIewboB7sgKRGp7QJTwdPc7nzuZliaoXPdy0h9JtrhebO0SoqYwlpKbyMOFQL0ukkTYbAlE4VwPG1wS0VPYPuz+XssyYYhCYqzs7HxomKZdKEEIHx7SRGDkmrXNLhVgpuUKjijnUlEGnzX171SIXIkrD6h5uya4Phs5RaWFvZVzqBA3OSdBlD8IqMkJr3EuS1MolwzOlj7ByCoPvOGo0rskmU3lxXjBxCKRm0= X-Forefront-Antispam-Report: CIP:12.216.194.146;CTRY:US;IPV:NLI;EFV:NLI;SFV:NSPM;SFS:(10009020)(6009001)(2980300002)(1110001)(1109001)(339900001)(189002)(199003)(189998001)(85426001)(11100500001)(5007970100001)(107886002)(50466002)(104016004)(229853001)(36756003)(586003)(5001920100001)(2201001)(86362001)(4001430100002)(50226001)(42186005)(105606002)(106466001)(48376002)(5001770100001)(19580395003)(5003940100001)(33646002)(5008740100001)(92566002)(5001970100001)(6806005)(87936001)(19580405001)(50986999)(47776003);DIR:OUT;SFP:1101;SCL:1;SRVR:AM3PR02MB113;H:ld-1.internal.tilera.com;FPR:;SPF:Fail;PTR:wb-fw1.tilera.com;MX:1;A:1;LANG:en; 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This should have been "Q = ACCESS_ONCE(P)". It later became "WRITE_ONCE(Q, P)". This doesn't match the following text, which is "Q = LOAD P". Change the statement to be "Q = READ_ONCE(P)". Signed-off-by: Chris Metcalf --- Documentation/memory-barriers.txt | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index aef9487303d0..85304ebd187c 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -194,7 +194,7 @@ There are some minimal guarantees that may be expected of a CPU: (*) On any given CPU, dependent memory accesses will be issued in order, with respect to itself. This means that for: - WRITE_ONCE(Q, P); smp_read_barrier_depends(); D = READ_ONCE(*Q); + Q = READ_ONCE(P); smp_read_barrier_depends(); D = READ_ONCE(*Q); the CPU will issue the following memory operations: @@ -202,9 +202,9 @@ There are some minimal guarantees that may be expected of a CPU: and always in that order. On most systems, smp_read_barrier_depends() does nothing, but it is required for DEC Alpha. The READ_ONCE() - and WRITE_ONCE() are required to prevent compiler mischief. Please - note that you should normally use something like rcu_dereference() - instead of open-coding smp_read_barrier_depends(). + is required to prevent compiler mischief. Please note that you + should normally use something like rcu_dereference() instead of + open-coding smp_read_barrier_depends(). (*) Overlapping loads and stores within a particular CPU will appear to be ordered within that CPU. This means that for: -- 2.1.2