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=-2.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 EA924C43331 for ; Tue, 12 Nov 2019 22:44:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C0E4C2196E for ; Tue, 12 Nov 2019 22:44:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="OcrokoyI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726983AbfKLWor (ORCPT ); Tue, 12 Nov 2019 17:44:47 -0500 Received: from mail-pf1-f177.google.com ([209.85.210.177]:43539 "EHLO mail-pf1-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726953AbfKLWor (ORCPT ); Tue, 12 Nov 2019 17:44:47 -0500 Received: by mail-pf1-f177.google.com with SMTP id 3so116740pfb.10; Tue, 12 Nov 2019 14:44:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=YP6HXQfqzmkkZWDyrOvnEJK7kISWvdIhSDIzf9Us7t8=; b=OcrokoyIrP6/2K/P/cPaAzNyafqPVWJGbTOeNMu4v5ASYwpfwhvhkehljA61C9f6GY XyNZ2lffsKCNHYu9LGAJCsSyg/Y/v8fyiKntIqItHyY9sVZLZKhGFTk+beOxYshM7iEm kmA76t5UG4F43tVYAYE6rljD5L+S1BGpml/gQ51PrjrrAVUgyaQ5SQGjlixMnrfrywKz Qa5Z1XIA2tqQGH2i6fYipScsVBYBMY/75ILLWSX0ggD5jDCN8h1tiYEHZ5O/7a2C3Ag+ Y+zjruCVPl1sNPcPKmestiVm9vRZOCaV7TJ4Pd9M9jtVWz2I211E0c3vps5vwy/4ewhL ZDEQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=YP6HXQfqzmkkZWDyrOvnEJK7kISWvdIhSDIzf9Us7t8=; b=kaeE+CcI7yDQ/BjLslpUpzCTWsJH7WExfVaAx4WEUHE2B+TuyZEcmDueR+jpbuIX9W WwO0kgchqdA2DW6BHvFMNpaRvnvFWRoTvi3zQYEToRFRC/9yCTjhz3ZrmP2rFfzu3QR3 YXOXKyPAQ43hP6laN9tlsg5oOUNDFDGQremkYG6x6Hq2uB/ge9k+41D9qng8kJ9+AvyU +uy7ygPSmZIoXmuW8BfW92PEslX2orYIfzGoZT0G4UKZCXrZLlpFn/iEFQ7Dz973uDBz J9FHgQ/S8TpkGBhzO04zydrTkcfhzy4+h4CGO3wWLG1EcfqVUdoE4fex7YZ8ZXIS7kRG I4ag== X-Gm-Message-State: APjAAAUoUaNrBFV6pxXIzhVfa+V5nQlhruO3ms7x7YxzjCvcTV1XXl91 7frgGXwYiDYyGw//Pr6Th/8LLzti X-Google-Smtp-Source: APXvYqweYCXNIbkVwq3Q28iNQJZLxJJhGWqlAFjHUjBOAF460Nj3e6jQLicpl8NTi7QmbU6q49jY2g== X-Received: by 2002:a63:d851:: with SMTP id k17mr7856562pgj.161.1573598685627; Tue, 12 Nov 2019 14:44:45 -0800 (PST) Received: from ast-mbp.dhcp.thefacebook.com ([2620:10d:c090:200::1:e001]) by smtp.gmail.com with ESMTPSA id i32sm20900pgl.73.2019.11.12.14.44.43 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 12 Nov 2019 14:44:44 -0800 (PST) Date: Tue, 12 Nov 2019 14:44:43 -0800 From: Alexei Starovoitov To: Eric Dumazet Cc: Alan Stern , Linus Torvalds , Marco Elver , Eric Dumazet , syzbot , linux-fsdevel , Linux Kernel Mailing List , syzkaller-bugs , Al Viro , Andrea Parri , "Paul E. McKenney" , LKMM Maintainers -- Akira Yokosawa Subject: Re: KCSAN: data-race in __alloc_file / __alloc_file Message-ID: <20191112224441.2kxmt727qy4l4ncb@ast-mbp.dhcp.thefacebook.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180223 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Nov 12, 2019 at 02:07:03PM -0800, Eric Dumazet wrote: > > I would prefer some kind of explicit marking, instead of a comment. > > Even if we prefer having a sane compiler, having these clearly > annotated can help > code readability quite a lot. Annotating every line where tsk->min_flt is used with a comment or explicit macro seems like a lot of churn. How about adding an attribute to a field ? Or an attribute to a type? clang attributes can be easily exteneded. We add bpf specific attributes that are known to clang only when 'clang -target bpf' is used. There could be x86 or generic attributes. Then one can do: typedef unsigned long __attribute__((ignore_data_race)) racy_u64; struct task_struct { racy_u64 min_flt; }; Hopefully less churn and clear signal to clang.