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From:   Arnd Bergmann <arnd@kernel.org>
Date:   Tue, 30 Mar 2021 11:00:36 +0200
Message-ID: <CAK8P3a3nUCGwPpE+E820DniY8Haz1Xx72pA38P6s5MWsbi0iAQ@mail.gmail.com>
Subject: Re: [PATCH 06/11] cgroup: fix -Wzero-length-bounds warnings
To:     =?UTF-8?Q?Michal_Koutn=C3=BD?= <mkoutny@suse.com>
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On Tue, Mar 30, 2021 at 10:41 AM Michal Koutn=C3=BD <mkoutny@suse.com> wrot=
e:
>
> On Mon, Mar 22, 2021 at 05:02:44PM +0100, Arnd Bergmann <arnd@kernel.org>=
 wrote:
> > I'm not sure what is expected to happen for such a configuration,
> > presumably these functions are never calls in that case.
> Yes, the functions you patched would only be called from subsystems or
> there should be no way to obtain a struct cgroup_subsys reference
> anyway (hence it's ok to always branch as if ss=3D=3DNULL).
>
> I'd prefer a variant that wouldn't compile the affected codepaths when
> there are no subsystems registered, however, I couldn't come up with a
> way how to do it without some preprocessor ugliness.

Would it be possible to enclose most or all of kernel/cgroup/cgroup.c
in an #ifdef CGROUP_SUBSYS_COUNT block? I didn't try that
myself, but this might be a way to guarantee that there cannot
be any callers (it would cause a link error).

> Reviewed-by: Michal Koutn=C3=BD <mkoutny@suse.com>

Thanks

        Arnd