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=-8.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 AA326C388F7 for ; Tue, 20 Oct 2020 18:43:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 61F6822200 for ; Tue, 20 Oct 2020 18:43:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437575AbgJTSmz (ORCPT ); Tue, 20 Oct 2020 14:42:55 -0400 Received: from smtprelay0130.hostedemail.com ([216.40.44.130]:38858 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2437566AbgJTSmy (ORCPT ); Tue, 20 Oct 2020 14:42:54 -0400 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay02.hostedemail.com (Postfix) with ESMTP id 43FA51260; Tue, 20 Oct 2020 18:42:51 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: humor84_3a06a8527241 X-Filterd-Recvd-Size: 4943 Received: from XPS-9350.home (unknown [47.151.133.149]) (Authenticated sender: joe@perches.com) by omf17.hostedemail.com (Postfix) with ESMTPA; Tue, 20 Oct 2020 18:42:43 +0000 (UTC) Message-ID: <3bc5c2e3b3edc22a4d167ec807ecdaaf8dcda76d.camel@perches.com> Subject: Re: [RFC] treewide: cleanup unreachable breaks From: Joe Perches To: Nick Desaulniers , Tom Rix 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 Date: Tue, 20 Oct 2020 11:42:42 -0700 In-Reply-To: References: <20201017160928.12698-1-trix@redhat.com> <20201018054332.GB593954@kroah.com> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.36.4-0ubuntu1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On Mon, 2020-10-19 at 12:42 -0700, 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. > > 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 > ... > 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. I suggest using W=1 as people that are doing cleanups generally use that and not W=123 or any other style. Every other use of W= is still quite noisy and these code warnings are relatively trivially to fix up.