On Tue, Mar 30, 2021 at 10:41 AM Michal Koutný <mkoutny@xxxxxxxx> wrote:
>
> On Mon, Mar 22, 2021 at 05:02:44PM +0100, Arnd Bergmann <arnd@xxxxxxxxxx> 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==NULL).
>
> 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 Koutný <mkoutny@xxxxxxxx>
Thanks
Arnd
