linux-kernel - Re: [PATCH 15/17] arch: fix asm-offsets.c building with -Wmissing-prototypes

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Date:   Sat, 12 Aug 2023 09:46:11 +0200
From:   "Arnd Bergmann" <arnd@...db.de>
To:     "Masahiro Yamada" <masahiroy@...nel.org>,
        "Arnd Bergmann" <arnd@...nel.org>
Cc:     "Andrew Morton" <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org,
        "Richard Henderson" <richard.henderson@...aro.org>,
        "Ivan Kokshaysky" <ink@...assic.park.msu.ru>,
        "Matt Turner" <mattst88@...il.com>,
        "Huacai Chen" <chenhuacai@...nel.org>,
        "WANG Xuerui" <kernel@...0n.name>,
        "David S . Miller" <davem@...emloft.net>,
        "Alexander Viro" <viro@...iv.linux.org.uk>,
        "Steven Rostedt" <rostedt@...dmis.org>,
        "Qing Zhang" <zhangqing@...ngson.cn>,
        "Donglin Peng" <pengdonglin@...gfor.com.cn>,
        "Qi Hu" <huqi@...ngson.cn>, linux-alpha@...r.kernel.org,
        linux-ia64@...r.kernel.org, loongarch@...ts.linux.dev,
        sparclinux@...r.kernel.org
Subject: Re: [PATCH 15/17] arch: fix asm-offsets.c building with -Wmissing-prototypes

On Sat, Aug 12, 2023, at 00:12, Masahiro Yamada wrote:
> On Sat, Aug 12, 2023 at 3:30 AM Arnd Bergmann <arnd@...nel.org> wrote:
>>
>> From: Arnd Bergmann <arnd@...db.de>
>>
>> When -Wmissing-prototypes is enabled, the some asm-offsets.c files fail
>> to build, even when this warning is disabled in the Makefile for normal
>> files:
>>
>> arch/sparc/kernel/asm-offsets.c:22:5: error: no previous prototype for 'sparc32_foo' [-Werror=missing-prototypes]
>> arch/sparc/kernel/asm-offsets.c:48:5: error: no previous prototype for 'foo' [-Werror=missing-prototypes]
>>
>> Address this by making use of the same trick we have on other architectures,
>> renaming the unused global function to main(), which has an implicit
>> prototype.
>
>
> main() only works for one function call, but
> there are some cases where splitting the code
> into some functions makes the code cleaner.

Right, I went with main() as that is already used on a couple
of architectures.

>> On loongarch, there are many functions in this file, so the trick does
>> not work, adding explicit declarations works around it in a slightly
>> more ugly way but is the best I could come up with here.
>
> I do not like repeating the function names.
>
> Could you try "static + __used" as in
> arch/x86/kernel/asm-offsets.c ?

Sure, that should work, I had not noticed x86 doing it like this
and I agree it's slightly nicer.

In this case, Thomas Bogendoerfer already merged my patch for MIPS
in 6.5. The loongarch file I change here is a copy of the same file,
so we probably want them to stay consistent, either keeping my
change for now, or reworking mips along the same lines.

    Arnd