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=-0.5 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 98E15C56201 for ; Wed, 25 Nov 2020 08:13:17 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2B73B20B80 for ; Wed, 25 Nov 2020 08:13:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="rGjC6KnG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2B73B20B80 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 702556E868; Wed, 25 Nov 2020 08:13:00 +0000 (UTC) Received: from mail-qk1-x743.google.com (mail-qk1-x743.google.com [IPv6:2607:f8b0:4864:20::743]) by gabe.freedesktop.org (Postfix) with ESMTPS id 1E9F96E5CA; Tue, 24 Nov 2020 23:46:35 +0000 (UTC) Received: by mail-qk1-x743.google.com with SMTP id q5so1122895qkc.12; Tue, 24 Nov 2020 15:46:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=H+rGPaoJ9R3rr7zK4cuxMwlBlLpdlGUAwlQnvIZjZd8=; b=rGjC6KnGzC9NIfLo6IfoTM7C5TiZmv4q08vYNRt8cewMWpFhbX886WW47/gIiopas/ e2jKhT73QJs/dRAIbILcJdQSFnVW9dal1rOBoIKd0ECBe+nqcukIgJrBRfX2wbZlPbrR 27L+0GE9CXpbAta7TZEIdoDweQHp+sEvmypYMH9hyutdrnRkkklGbspFfFiZY+HYfDHj jsH/8tjPy+0JiTdJWitSDoQxXZntWXoEWL0cWLR+fmdpM332GBoSCjfuWUHY88IWDiPh 04ztpEPYlCjpB7IXy1yQhW/otwe7DgKcwtOpyIrk5XdAw3ZKiOAkll08YWpT8S+NhzMx e/Gw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=H+rGPaoJ9R3rr7zK4cuxMwlBlLpdlGUAwlQnvIZjZd8=; b=TYffeSRbe43ODMjM/MAQ0pbAsS+9hDYoSLz32LAh9hG9Op3JqBa3V4pOJtni0SuVPt 1MOmhxEWNAl2DdpdTS1iSpV1xdxvr3lquvTXNSAWs8BGTg8jVHrqxdZ6mUecAQML3n+h D5moQqhzVSJKYgIEWxcvwzgzRA6oM4fjUey/Qk5neci8zl/wIUC82m/lTVf/53Su4I8x JVyXLaVJnMXye/bMOO4330yCxyj75ovqSQKGpel6mDvKd/71heGA84hO3I2tcypRLsgw GMYFMpIQwyS9rFMowtraYpvGAljs9KX23R+2aXs71p+popqfItFuIHM7b3G5ltxNAZyQ LTbw== X-Gm-Message-State: AOAM53365CnpBUGHPLw4uGuAoAc1XyZOiK4R7TTOkmnCb2CpG4z9Ll6U qG0ptjliax1TesISt3SpA5sjgZvXgBp/gut6NLc= X-Google-Smtp-Source: ABdhPJzOwu2wFsHHn8A1YNPfZeoFLdmnMgNDFogUYxSXdSyfkKR4RJ+IXZpEdbdh4p7RHhstmUROclNZOq0Hltp8jFg= X-Received: by 2002:a5b:40e:: with SMTP id m14mr627984ybp.33.1606261594309; Tue, 24 Nov 2020 15:46:34 -0800 (PST) MIME-Version: 1.0 References: <20201120105344.4345c14e@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <202011201129.B13FDB3C@keescook> <20201120115142.292999b2@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <202011220816.8B6591A@keescook> <9b57fd4914b46f38d54087d75e072d6e947cb56d.camel@HansenPartnership.com> In-Reply-To: From: Miguel Ojeda Date: Wed, 25 Nov 2020 00:46:23 +0100 Message-ID: Subject: Re: [PATCH 000/141] Fix fall-through warnings for Clang To: Finn Thain X-Mailman-Approved-At: Wed, 25 Nov 2020 08:11:52 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alsa-devel@alsa-project.org, linux-atm-general@lists.sourceforge.net, reiserfs-devel@vger.kernel.org, linux-iio@vger.kernel.org, linux-wireless , linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, "Gustavo A. R. Silva" , James Bottomley , linux-ide@vger.kernel.org, dm-devel@redhat.com, keyrings@vger.kernel.org, linux-mtd@lists.infradead.org, GR-everest-linux-l2@marvell.com, wcn36xx@lists.infradead.org, samba-technical@lists.samba.org, linux-i3c@lists.infradead.org, linux1394-devel@lists.sourceforge.net, linux-afs@lists.infradead.org, usb-storage@lists.one-eyed-alien.net, drbd-dev@lists.linbit.com, devel@driverdev.osuosl.org, linux-cifs@vger.kernel.org, rds-devel@oss.oracle.com, Nick Desaulniers , linux-scsi@vger.kernel.org, Nathan Chancellor , linux-rdma@vger.kernel.org, oss-drivers@netronome.com, bridge@lists.linux-foundation.org, linux-security-module@vger.kernel.org, amd-gfx@lists.freedesktop.org, linux-stm32@st-md-mailman.stormreply.com, cluster-devel@redhat.com, linux-acpi@vger.kernel.org, coreteam@netfilter.org, intel-wired-lan@lists.osuosl.org, linux-input , Miguel Ojeda , Jakub Kicinski , Ext4 Developers List , Linux Media Mailing List , Kees Cook , selinux@vger.kernel.org, linux-arm-msm@vger.kernel.org, intel-gfx@lists.freedesktop.org, linux-geode@lists.infradead.org, linux-can@vger.kernel.org, linux-block@vger.kernel.org, linux-gpio@vger.kernel.org, op-tee@lists.trustedfirmware.org, linux-mediatek@lists.infradead.org, xen-devel@lists.xenproject.org, nouveau@lists.freedesktop.org, linux-hams@vger.kernel.org, ceph-devel@vger.kernel.org, virtualization@lists.linux-foundation.org, target-devel@vger.kernel.org, Linux ARM , linux-hwmon@vger.kernel.org, linux-watchdog@vger.kernel.org, linux-nfs@vger.kernel.org, GR-Linux-NIC-Dev@marvell.com, tipc-discussion@lists.sourceforge.net, Linux-MM , Network Development , linux-decnet-user@lists.sourceforge.net, linux-mmc@vger.kernel.org, linux-kernel , linux-renesas-soc@vger.kernel.org, linux-sctp@vger.kernel.org, linux-usb@vger.kernel.org, netfilter-devel@vger.kernel.org, Linux Crypto Mailing List , patches@opensource.cirrus.com, Joe Perches , linux-integrity@vger.kernel.org, "maintainer:X86 ARCHITECTURE \(32-BIT AND 64-BIT\)" , linux-hardening@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Tue, Nov 24, 2020 at 1:58 AM Finn Thain wrote: > > What I meant was that you've used pessimism as if it was fact. "future mistakes that it might prevent" is neither pessimism nor states a fact. > For example, "There is no way to guess what the effect would be if the > compiler trained programmers to add a knee-jerk 'break' statement to avoid > a warning". It is only knee-jerk if you think you are infallible. > Moreover, what I meant was that preventing programmer mistakes is a > problem to be solved by development tools This warning comes from a development tool -- the compiler. > The idea that retro-fitting new > language constructs onto mature code is somehow necessary to "prevent > future mistakes" is entirely questionable. The kernel is not a frozen codebase. Further, "mature code vs. risk of change" arguments don't apply here because the semantics of the program and binary output isn't changing. > Sure. And if you put -Wimplicit-fallthrough into the Makefile and if that > leads to well-intentioned patches that cause regressions, it is partly on > you. Again: adding a `fallthrough` does not change the program semantics. If you are a maintainer and want to cross-check, compare the codegen. > Have you ever considered the overall cost of the countless > -Wpresume-incompetence flags? Yeah: negative. On the other hand, the overall cost of the countless -fI-am-infallible flags is very noticeable. > Perhaps you pay the power bill for a build farm that produces logs that > no-one reads? Perhaps you've run git bisect, knowing that the compiler > messages are not interesting? Or compiled software in using a language > that generates impenetrable messages? If so, here's a tip: > > # grep CFLAGS /etc/portage/make.conf > CFLAGS="... -Wno-all -Wno-extra ..." > CXXFLAGS="${CFLAGS}" > > Now allow me some pessimism: the hardware upgrades, gigawatt hours and > wait time attributable to obligatory static analyses are a net loss. If you really believe compiler warnings and static analysis are useless and costly, I think there is not much point in continuing the discussion. > No, it's not for me to prove that such patches don't affect code > generation. That's for the patch author and (unfortunately) for reviewers. I was not asking you to prove it. I am stating that proving it is very easy. Cheers, Miguel _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel