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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 AC3C8C2D0CD for ; Tue, 17 Dec 2019 12:23:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8DD92206D7 for ; Tue, 17 Dec 2019 12:23:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727820AbfLQMXg (ORCPT ); Tue, 17 Dec 2019 07:23:36 -0500 Received: from vmicros1.altlinux.org ([194.107.17.57]:47474 "EHLO vmicros1.altlinux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726191AbfLQMXf (ORCPT ); Tue, 17 Dec 2019 07:23:35 -0500 Received: from imap.altlinux.org (imap.altlinux.org [194.107.17.38]) by vmicros1.altlinux.org (Postfix) with ESMTP id CD68772CCD5; Tue, 17 Dec 2019 15:23:32 +0300 (MSK) Received: from altlinux.org (sole.flsd.net [185.75.180.6]) by imap.altlinux.org (Postfix) with ESMTPSA id A87B74A4AEF; Tue, 17 Dec 2019 15:23:32 +0300 (MSK) Date: Tue, 17 Dec 2019 15:23:32 +0300 From: Vitaly Chikunov To: Arnaldo Carvalho de Melo , Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org Cc: "Dmitry V . Levin" , Josh Poimboeuf , Vineet Gupta , stable@vger.kernel.org Subject: Re: [PATCH] tools lib: Disable redundant-delcs error for strlcpy Message-ID: <20191217122331.4g5atx7in6njjlw4@altlinux.org> Mail-Followup-To: Arnaldo Carvalho de Melo , Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, "Dmitry V . Levin" , Josh Poimboeuf , Vineet Gupta , stable@vger.kernel.org References: <20191208214607.20679-1-vt@altlinux.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20191208214607.20679-1-vt@altlinux.org> User-Agent: NeoMutt/20171215-106-ac61c7 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Arnaldo, Ping. Can you accept or comment on this patch? There is further explanations of it: 1. It seems that people putting strlcpy() into the tools was already aware of the problems it causes and tried to solve them. Probably, that's why they put `__weak` attribute on it (so it would be linkable in the presence of another strlcpy). Then `#ifndef __UCLIBC__`ed and later `#if defined(__GLIBC__) && !defined(__UCLIBC__)` its declaration. But, solution was incomplete and could be improved to make kernel buildable on more systems (where libc contains strlcpy). There is not need to make `redundant redeclaration` warning an error in this case. 2. `#pragma GCC diagnostic ignored` trick is already used multiple times in the kernel: $ git grep '#pragma GCC diagnostic ignored' arch/arm/lib/xor-neon.c:#pragma GCC diagnostic ignored "-Wunused-variable" tools/build/feature/test-gtk2-infobar.c:#pragma GCC diagnostic ignored "-Wstrict-prototypes" tools/build/feature/test-gtk2.c:#pragma GCC diagnostic ignored "-Wstrict-prototypes" tools/include/linux/string.h:#pragma GCC diagnostic ignored "-Wredundant-decls" tools/lib/bpf/libbpf.c:#pragma GCC diagnostic ignored "-Wformat-nonliteral" tools/perf/ui/gtk/gtk.h:#pragma GCC diagnostic ignored "-Wstrict-prototypes" tools/testing/selftests/kvm/lib/assert.c:#pragma GCC diagnostic ignored "-Wunused-result" tools/usb/ffs-test.c:#pragma GCC diagnostic ignored "-Wdeprecated-declarations" So the solution does not seem alien in the kernel and should be acceptable. (I also send this to another of your emails in case I used wrong one before.) Thanks, On Mon, Dec 09, 2019 at 12:46:07AM +0300, Vitaly Chikunov wrote: > Disable `redundant-decls' error for strlcpy declaration and solve build > error allowing users to compile vanilla kernels. > > When glibc have strlcpy (such as in ALT linux since 2004) objtool and > perf build fails with something like: > > In file included from exec-cmd.c:3: > tools/include/linux/string.h:20:15: error: redundant redeclaration of ‘strlcpy’ [-Werror=redundant-decls] > 20 | extern size_t strlcpy(char *dest, const char *src, size_t size); > | ^~~~~~~ > > It's very hard to produce a perfect fix for that since it is a header > file indirectly pulled from many sources from different Makefile builds. > > Fixes: ce99091 ("perf tools: Move strlcpy() from perf to tools/lib/string.c") > Fixes: 0215d59 ("tools lib: Reinstate strlcpy() header guard with __UCLIBC__") > Signed-off-by: Vitaly Chikunov > Cc: Dmitry V. Levin > Cc: Josh Poimboeuf > Cc: Vineet Gupta > Cc: stable@vger.kernel.org > --- > tools/include/linux/string.h | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/tools/include/linux/string.h b/tools/include/linux/string.h > index 980cb9266718..99ede7f5dfb8 100644 > --- a/tools/include/linux/string.h > +++ b/tools/include/linux/string.h > @@ -17,7 +17,10 @@ int strtobool(const char *s, bool *res); > * However uClibc headers also define __GLIBC__ hence the hack below > */ > #if defined(__GLIBC__) && !defined(__UCLIBC__) > +#pragma GCC diagnostic push > +#pragma GCC diagnostic ignored "-Wredundant-decls" > extern size_t strlcpy(char *dest, const char *src, size_t size); > +#pragma GCC diagnostic pop > #endif > > char *str_error_r(int errnum, char *buf, size_t buflen);