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=-17.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 1DD81C33C9A for ; Thu, 14 Nov 2019 18:04:08 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CAB542072E for ; Thu, 14 Nov 2019 18:04:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="HvmXn12w" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CAB542072E Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 34BB36B0008; Thu, 14 Nov 2019 13:04:06 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2D53C6B000A; Thu, 14 Nov 2019 13:04:06 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 177DF6B000C; Thu, 14 Nov 2019 13:04:06 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0157.hostedemail.com [216.40.44.157]) by kanga.kvack.org (Postfix) with ESMTP id F0F426B0008 for ; Thu, 14 Nov 2019 13:04:05 -0500 (EST) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 7B7C7824999B for ; Thu, 14 Nov 2019 18:04:05 +0000 (UTC) X-FDA: 76155656850.24.title09_5dd8c4988e613 X-HE-Tag: title09_5dd8c4988e613 X-Filterd-Recvd-Size: 5313 Received: from mail-qv1-f74.google.com (mail-qv1-f74.google.com [209.85.219.74]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Thu, 14 Nov 2019 18:04:04 +0000 (UTC) Received: by mail-qv1-f74.google.com with SMTP id b6so4667383qvo.4 for ; Thu, 14 Nov 2019 10:04:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=c5ZdhZ0YGUmz1p5pK6AEd80tJtC02zu3w0ESO5REMCw=; b=HvmXn12wl0qX/E3Rsy6XqFvz7iTSNFZJIf1ZuTbKx3Tf8RzcRepEE5HIoqTt7DRQTD BhA9D84TWAiMyyFx8ULMX+Dm3fgOaUFKhbkkAo23XPCj17yXfdvGlxXC3T5hbr6vY+2E /+LOp1OCb1YMNQGDPTs/kvDX3vj+tn43TQfV5DRowqaLe3Rsy0CJONrwytkRB963xQt2 RhDiCzHw1wa4bGdIbJDAOtNuLIelDK4ow+jKCLXn6s6/F6/Dqiq3o5xn1VqYsLMdgaay aADxdgs93rup9XUu0H6SUFQRc26NJEOqN8mzXO6Y75vGKv4cuA3T/r8IkQiHZQ5uN5h2 exoA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=c5ZdhZ0YGUmz1p5pK6AEd80tJtC02zu3w0ESO5REMCw=; b=QNL7X8SNEyfUaqW5xFejJ7p2n5HTeh9A3jcV61QVm0QTecND5WaFehsKDJ8n+g7Qq7 71XksM+UdChjs34lV099AQ4MjP/lBmSmVIAwSDSrXd6/e7KDESQpa+e8XfFl2JrgMWMm bP68dw1m3spcPAe1QPTbX9UwTbymZ7RCbWFciKNb08mOvp6Zlv19Git/U5mDjM1wgLFm ICFk/czFvLURB9Lbw7YDWRcjwt53bUH+0JBvZudaS6TR9kOib+gdCqeP/IeGOZOP2u+K ekvBXdxIYN/cutCCnzDAXes+eYbHtv9nWnLYlwrd0+KYS6NNvuzjGF/oa02vjC5rL0bj Z5lg== X-Gm-Message-State: APjAAAXyqRmEUrL0f1erz+G45A7CsvrCg1m27Dsi5Qo30mT07z34BbtC 9Q4ngc8s07ESHd+8qwUAxWsAAMf5kQ== X-Google-Smtp-Source: APXvYqwUlw4hUlsakl9iLIPewvS2JHArNK+4NJ+usYinBWA3JzGZ7XeylKBeWUNZaEF3evwOmxW2Hl7CfA== X-Received: by 2002:a05:6214:1332:: with SMTP id c18mr7908552qvv.213.1573754643719; Thu, 14 Nov 2019 10:04:03 -0800 (PST) Date: Thu, 14 Nov 2019 19:02:55 +0100 In-Reply-To: <20191114180303.66955-1-elver@google.com> Message-Id: <20191114180303.66955-3-elver@google.com> Mime-Version: 1.0 References: <20191114180303.66955-1-elver@google.com> X-Mailer: git-send-email 2.24.0.rc1.363.gb1bccd3e3d-goog Subject: [PATCH v4 02/10] include/linux/compiler.h: Introduce data_race(expr) macro From: Marco Elver To: elver@google.com Cc: akiyks@gmail.com, stern@rowland.harvard.edu, glider@google.com, parri.andrea@gmail.com, andreyknvl@google.com, luto@kernel.org, ard.biesheuvel@linaro.org, arnd@arndb.de, boqun.feng@gmail.com, bp@alien8.de, dja@axtens.net, dlustig@nvidia.com, dave.hansen@linux.intel.com, dhowells@redhat.com, dvyukov@google.com, hpa@zytor.com, mingo@redhat.com, j.alglave@ucl.ac.uk, joel@joelfernandes.org, corbet@lwn.net, jpoimboe@redhat.com, luc.maranget@inria.fr, mark.rutland@arm.com, npiggin@gmail.com, paulmck@kernel.org, peterz@infradead.org, tglx@linutronix.de, will@kernel.org, edumazet@google.com, kasan-dev@googlegroups.com, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-efi@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, Linus Torvalds Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 --- v4: * Introduce this patch to KCSAN series. --- include/linux/compiler.h | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index c42fa83f23fb..7d3e77781578 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__ */ /* -- 2.24.0.rc1.363.gb1bccd3e3d-goog