On Tue, Mar 30, 2021 at 10:41 AM Michal Koutný mkoutny@suse.com wrote:
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==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@suse.com
Thanks
Arnd