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=-10.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 B6EA7C61DD8 for ; Tue, 20 Oct 2020 13:56:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5D56F22240 for ; Tue, 20 Oct 2020 13:56:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="QUp+Tm/4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407746AbgJTN4Q (ORCPT ); Tue, 20 Oct 2020 09:56:16 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:38798 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2407728AbgJTN4F (ORCPT ); Tue, 20 Oct 2020 09:56:05 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603202163; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=HyQ28xr5/lapv6azTtFCvHFT5XQ1+OzeHk+84iEm66Y=; b=QUp+Tm/49C2D2ArfwdGiXcYEZLmxY3ITF9bXZyS+HEfcJJoqaGxmch+2EHiNHeADDWpHNz Ouzap4oFcZixuWmorb4Ub+lRVmWRZDipZO+0tL8W1vnU06zVM/xfLz81/8VfcBPp80A1RW EdBHqnK2mgm1gY9dzcmZeB2rW1Al8Fc= Received: from mail-qv1-f72.google.com (mail-qv1-f72.google.com [209.85.219.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-96-Yd-P-HKHMb67wnlxmnmwXg-1; Tue, 20 Oct 2020 09:56:01 -0400 X-MC-Unique: Yd-P-HKHMb67wnlxmnmwXg-1 Received: by mail-qv1-f72.google.com with SMTP id u17so1402044qvt.23 for ; Tue, 20 Oct 2020 06:56:01 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=HyQ28xr5/lapv6azTtFCvHFT5XQ1+OzeHk+84iEm66Y=; b=mCyqZ3aiOB1buCkLM32MJjiKPdpd79KjFIp0QUobwkkyUgCoRWSbhsVR/JYKZR7fas SLKlClqYUIdghP+KTJpRnjE2+HlsB+aZfbSjePQPsSAh9SmtJcpha6pR+m2Dhhgbk4Ts /j6AXdN1xOeJOVmXM92BhyWXsNMC7CUs+xk3ICvjejISVS837TonI+EPp7A7jWeg2G9F QaR2yFTSwfYY0gf8OzKvur/5tIAl1acWqgs2X9S94avUkut9YsR/DA4bZwpxLSH8vtIl qv/x8hXYeszPBZ56OCjOWxOSa6gkezp5SAJ2q6dBoJoQl+nf6wGlobjItKaBbjsfJ6MW 1nlA== X-Gm-Message-State: AOAM531ForI9wq6cnSzmYzo0iILmyqJB+cyGPJT6xr23+QZDwNl8jMgW nKjB/XXNDzvnvzXh3k0nSLLDGFIaiRvMjkDwkaQpnaERB/uCloxB1/4C7z47J9XT90vtV81KmkE YipcgcePs98vPruFUP4nf X-Received: by 2002:a05:6214:174f:: with SMTP id dc15mr3370423qvb.25.1603202160687; Tue, 20 Oct 2020 06:56:00 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyLUAfqrAOJzxwKF3+voCBF5yQYNbMOvfOkDZhumkJj3bEnT15V4x8vUJ5iQ5pWt9KusIZtsQ== X-Received: by 2002:a05:6214:174f:: with SMTP id dc15mr3370377qvb.25.1603202160139; Tue, 20 Oct 2020 06:56:00 -0700 (PDT) Received: from trix.remote.csb (075-142-250-213.res.spectrum.com. [75.142.250.213]) by smtp.gmail.com with ESMTPSA id b8sm775938qkn.133.2020.10.20.06.55.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 20 Oct 2020 06:55:59 -0700 (PDT) Subject: Re: [RFC] treewide: cleanup unreachable breaks To: Nick Desaulniers Cc: LKML , linux-edac@vger.kernel.org, linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, xen-devel@lists.xenproject.org, linux-block@vger.kernel.org, openipmi-developer@lists.sourceforge.net, "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" , Linux ARM , linux-power@fi.rohmeurope.com, linux-gpio@vger.kernel.org, amd-gfx list , dri-devel , nouveau@lists.freedesktop.org, virtualization@lists.linux-foundation.org, spice-devel@lists.freedesktop.org, linux-iio@vger.kernel.org, linux-amlogic@lists.infradead.org, industrypack-devel@lists.sourceforge.net, linux-media@vger.kernel.org, MPT-FusionLinux.pdl@broadcom.com, linux-scsi@vger.kernel.org, linux-mtd@lists.infradead.org, linux-can@vger.kernel.org, Network Development , intel-wired-lan@lists.osuosl.org, ath10k@lists.infradead.org, linux-wireless , linux-stm32@st-md-mailman.stormreply.com, linux-nfc@lists.01.org, linux-nvdimm , linux-pci@vger.kernel.org, linux-samsung-soc@vger.kernel.org, platform-driver-x86@vger.kernel.org, patches@opensource.cirrus.com, storagedev@microchip.com, devel@driverdev.osuosl.org, linux-serial@vger.kernel.org, linux-usb@vger.kernel.org, usb-storage@lists.one-eyed-alien.net, linux-watchdog@vger.kernel.org, ocfs2-devel@oss.oracle.com, bpf , linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, keyrings@vger.kernel.org, alsa-devel@alsa-project.org, clang-built-linux , Greg KH , George Burgess , Joe Perches References: <20201017160928.12698-1-trix@redhat.com> <20201018054332.GB593954@kroah.com> From: Tom Rix Message-ID: Date: Tue, 20 Oct 2020 06:55:52 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On 10/19/20 12:42 PM, Nick Desaulniers wrote: > On Sat, Oct 17, 2020 at 10:43 PM Greg KH wrote: >> On Sat, Oct 17, 2020 at 09:09:28AM -0700, trix@redhat.com wrote: >>> From: Tom Rix >>> >>> This is a upcoming change to clean up a new warning treewide. >>> I am wondering if the change could be one mega patch (see below) or >>> normal patch per file about 100 patches or somewhere half way by collecting >>> early acks. >> Please break it up into one-patch-per-subsystem, like normal, and get it >> merged that way. >> >> Sending us a patch, without even a diffstat to review, isn't going to >> get you very far... > Tom, > If you're able to automate this cleanup, I suggest checking in a > script that can be run on a directory. Then for each subsystem you > can say in your commit "I ran scripts/fix_whatever.py on this subdir." > Then others can help you drive the tree wide cleanup. Then we can > enable -Wunreachable-code-break either by default, or W=2 right now > might be a good idea. I should have waited for Joe Perches's fixer addition to checkpatch :) The easy fixes I did only cover about 1/2 of the problems. Remaining are mostly nested switches, which from a complexity standpoint is bad. > > Ah, George (gbiv@, cc'ed), did an analysis recently of > `-Wunreachable-code-loop-increment`, `-Wunreachable-code-break`, and > `-Wunreachable-code-return` for Android userspace. From the review: > ``` > Spoilers: of these, it seems useful to turn on > -Wunreachable-code-loop-increment and -Wunreachable-code-return by > default for Android In my simple add-a-cflag bot, i see there are about 250 issues for -Wunreachable-code-return. I'll see about doing this one next. > ... > While these conventions about always having break arguably became > obsolete when we enabled -Wfallthrough, my sample turned up zero > potential bugs caught by this warning, and we'd need to put a lot of > effort into getting a clean tree. So this warning doesn't seem to be > worth it. > ``` > Looks like there's an order of magnitude of `-Wunreachable-code-break` > than the other two. > > We probably should add all 3 to W=2 builds (wrapped in cc-option). > I've filed https://github.com/ClangBuiltLinux/linux/issues/1180 to > follow up on. Yes, i think think these should be added. Tom