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Date:   Thu, 18 May 2023 15:23:39 +0200
From:   "Arnd Bergmann" <arnd@arndb.de>
To:     "Andrew Morton" <akpm@linux-foundation.org>,
        "Arnd Bergmann" <arnd@kernel.org>
Cc:     "Nick Terrell" <terrelln@fb.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] decompressor: provide missing prototypes
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On Wed, May 17, 2023, at 22:49, Andrew Morton wrote:
> On Wed, 17 May 2023 15:19:31 +0200 Arnd Bergmann <arnd@kernel.org> wrote:
>
>> From: Arnd Bergmann <arnd@arndb.de>
>> 
>> The entry points for the decompressor don't always have a prototype
>> included in the .c file:
>> 
>> lib/decompress_inflate.c:42:17: error: no previous prototype for '__gunzip' [-Werror=missing-prototypes]
>> lib/decompress_unxz.c:251:17: error: no previous prototype for 'unxz' [-Werror=missing-prototypes]
>> lib/decompress_unzstd.c:331:17: error: no previous prototype for 'unzstd' [-Werror=missing-prototypes]
>> 
>> include the correct headers for unxz and unzstd, and mark the
>> inflate function above as unconditionally 'static' to avoid
>> these warnings.
>
> These are errors, not warnings?
>
> Under what circumstances do they occur?

Running "make W=1" turns these errors on as warnings, enabling
CONFIG_WERROR turns all warnings into errors.

> Shouldn't we cc:stable?  If so, do we have a suitable Fixes: target?

I have sent 140 patches for these, there is probably no point in backporting
them all. My hope is that we can enable -Wmissing-prototypes by default
after these are all merged, but that patch would not get backported
either.

I meant to include a link with the explanations to

https://people.kernel.org/arnd/missing-prototype-warnings-in-the-kernel

in my series but didn't have that in the separate patches.

     Arnd