linux-kernel - Re: [PATCH v2] tools lib: Fix builds when glibc contains strlcpy

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Date:   Sat, 21 Dec 2019 03:33:54 +0300
From:   "Dmitry V. Levin" <ldv@...linux.org>
To:     Vitaly Chikunov <vt@...linux.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Vineet Gupta <Vineet.Gupta1@...opsys.com>,
        stable@...r.kernel.org
Subject: Re: [PATCH v2] tools lib: Fix builds when glibc contains strlcpy

On Sat, Dec 21, 2019 at 02:52:39AM +0300, Vitaly Chikunov wrote:
> Disable a couple of compilation warning (which are treated as errors) on
> strlcpy definition and declaration, allow users to compile perf and
> kernel (objtool).
> 
> 1. When glibc have strlcpy (such as in ALT Linux since 2004) objtool and
> perf build fails with this (in gcc):
> 
>   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);
> 
> 2. Clang ignores `-Wredundant-decls', but produces another warning when
> building perf:
> 
>     CC       util/string.o
>   ../lib/string.c:99:8: error: attribute declaration must precede definition [-Werror,-Wignored-attributes]
>   size_t __weak strlcpy(char *dest, const char *src, size_t size)
>   ../../tools/include/linux/compiler.h:66:34: note: expanded from macro '__weak'
>   # define __weak                 __attribute__((weak))
>   /usr/include/bits/string_fortified.h:151:8: note: previous definition is here
>   __NTH (strlcpy (char *__restrict __dest, const char *__restrict __src,
> 
> 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 <vt@...linux.org>
> Cc: Dmitry V. Levin <ldv@...linux.org>
> Cc: Josh Poimboeuf <jpoimboe@...hat.com>
> Cc: Vineet Gupta <Vineet.Gupta1@...opsys.com>
> Cc: stable@...r.kernel.org

Resolves: https://bugzilla.kernel.org/show_bug.cgi?id=118481
Reviewed-by: Dmitry V. Levin <ldv@...linux.org>


-- 
ldv