From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 44723C432C0 for ; Fri, 22 Nov 2019 11:18:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2490B20718 for ; Fri, 22 Nov 2019 11:18:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728624AbfKVLSv (ORCPT ); Fri, 22 Nov 2019 06:18:51 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:34686 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729871AbfKVKsP (ORCPT ); Fri, 22 Nov 2019 05:48:15 -0500 Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1iY6Ty-00035I-LS; Fri, 22 Nov 2019 11:48:10 +0100 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id 41F1F1C1A67; Fri, 22 Nov 2019 11:48:07 +0100 (CET) Date: Fri, 22 Nov 2019 10:48:07 -0000 From: "tip-bot2 for Marco Elver" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: locking/kcsan] include/linux/compiler.h: Introduce data_race(expr) macro Cc: Marco Elver , Alan Stern , Eric Dumazet , Linus Torvalds , "Paul E. McKenney" , x86 , LKML MIME-Version: 1.0 Message-ID: <157441968719.21853.2447125063229216269.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the locking/kcsan branch of tip: Commit-ID: c48981eeb0d56e107691df590007d6699441a689 Gitweb: https://git.kernel.org/tip/c48981eeb0d56e107691df590007d6699441a689 Author: Marco Elver AuthorDate: Thu, 14 Nov 2019 19:02:55 +01:00 Committer: Paul E. McKenney CommitterDate: Sat, 16 Nov 2019 07:23:13 -08:00 include/linux/compiler.h: Introduce data_race(expr) macro This introduces the data_race(expr) macro, which can be used to annotate expressions for purposes of (1) documenting, and (2) giving tooling such as KCSAN information about which data races are deemed "safe". More context: http://lkml.kernel.org/r/CAHk-=wg5CkOEF8DTez1Qu0XTEFw_oHhxN98bDnFqbY7HL5AB2g@mail.gmail.com Signed-off-by: Marco Elver Cc: Alan Stern Cc: Eric Dumazet Cc: Linus Torvalds Cc: Paul E. McKenney Signed-off-by: Paul E. McKenney --- include/linux/compiler.h | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index c42fa83..7d3e777 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -310,6 +310,26 @@ unsigned long read_word_at_a_time(const void *addr) __u.__val; \ }) +#include + +/* + * data_race: macro to document that accesses in an expression may conflict with + * other concurrent accesses resulting in data races, but the resulting + * behaviour is deemed safe regardless. + * + * This macro *does not* affect normal code generation, but is a hint to tooling + * that data races here should be ignored. + */ +#define data_race(expr) \ + ({ \ + typeof(({ expr; })) __val; \ + kcsan_nestable_atomic_begin(); \ + __val = ({ expr; }); \ + kcsan_nestable_atomic_end(); \ + __val; \ + }) +#else + #endif /* __KERNEL__ */ /*