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=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 BF738C433E1 for ; Fri, 22 May 2020 16:08:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A92E220829 for ; Fri, 22 May 2020 16:08:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730608AbgEVQIy (ORCPT ); Fri, 22 May 2020 12:08:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41092 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729040AbgEVQIv (ORCPT ); Fri, 22 May 2020 12:08:51 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99F6BC05BD43; Fri, 22 May 2020 09:08:51 -0700 (PDT) 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 1jcAE3-00009T-0i; Fri, 22 May 2020 18:08:47 +0200 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id AAF171C0475; Fri, 22 May 2020 18:08:46 +0200 (CEST) Date: Fri, 22 May 2020 16:08:46 -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] compiler.h: Remove data_race() and unnecessary checks from {READ,WRITE}_ONCE() Cc: Marco Elver , Borislav Petkov , "Peter Zijlstra (Intel)" , Will Deacon , x86 , LKML In-Reply-To: <20200521142047.169334-9-elver@google.com> References: <20200521142047.169334-9-elver@google.com> MIME-Version: 1.0 Message-ID: <159016372659.17951.9279233583704092655.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: 777f73c4e79106d45b304f6af0d31917864dbdf1 Gitweb: https://git.kernel.org/tip/777f73c4e79106d45b304f6af0d31917864dbdf1 Author: Marco Elver AuthorDate: Thu, 21 May 2020 16:20:44 +02:00 Committer: Borislav Petkov CommitterDate: Fri, 22 May 2020 15:19:53 +02:00 compiler.h: Remove data_race() and unnecessary checks from {READ,WRITE}_ONCE() The volatile accesses no longer need to be wrapped in data_race() because compilers that emit instrumentation distinguishing volatile accesses are required for KCSAN. Consequently, the explicit kcsan_check_atomic*() are no longer required either since the compiler emits instrumentation distinguishing the volatile accesses. Finally, simplify __READ_ONCE_SCALAR() and remove __WRITE_ONCE_SCALAR(). [ bp: Convert commit message to passive voice. ] Signed-off-by: Marco Elver Signed-off-by: Borislav Petkov Acked-by: Peter Zijlstra (Intel) Acked-by: Will Deacon Link: https://lkml.kernel.org/r/20200521142047.169334-9-elver@google.com --- include/linux/compiler.h | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 17c98b2..7444f02 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -228,9 +228,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, #define __READ_ONCE_SCALAR(x) \ ({ \ - typeof(x) *__xp = &(x); \ - __unqual_scalar_typeof(x) __x = data_race(__READ_ONCE(*__xp)); \ - kcsan_check_atomic_read(__xp, sizeof(*__xp)); \ + __unqual_scalar_typeof(x) __x = __READ_ONCE(x); \ smp_read_barrier_depends(); \ (typeof(x))__x; \ }) @@ -246,17 +244,10 @@ do { \ *(volatile typeof(x) *)&(x) = (val); \ } while (0) -#define __WRITE_ONCE_SCALAR(x, val) \ -do { \ - typeof(x) *__xp = &(x); \ - kcsan_check_atomic_write(__xp, sizeof(*__xp)); \ - data_race(({ __WRITE_ONCE(*__xp, val); 0; })); \ -} while (0) - #define WRITE_ONCE(x, val) \ do { \ compiletime_assert_rwonce_type(x); \ - __WRITE_ONCE_SCALAR(x, val); \ + __WRITE_ONCE(x, val); \ } while (0) #ifdef CONFIG_KASAN