Re: [PATCH 4/4] cgroup: Do not report unavailable v1 controllers in /proc/cgroups

[Waiman Long <longman@redhat.com>]

On 9/9/24 12:32, Michal Koutný wrote:
> This is a followup to CONFIG-urability of cpuset and memory controllers
> for v1 hierarchies. Make the output in /proc/cgroups reflect that
> !CONFIG_CPUSETS_V1 is like !CONFIG_CPUSETS and
> !CONFIG_MEMCG_V1 is like !CONFIG_MEMCG.
>
> The intended effect is that hiding the unavailable controllers will hint
> users not to try mounting them on v1.
>
> Signed-off-by: Michal Koutný <mkoutny@suse.com>
> ---
>   kernel/cgroup/cgroup-v1.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
> index 784337694a4be..e28d5f0d20ed0 100644
> --- a/kernel/cgroup/cgroup-v1.c
> +++ b/kernel/cgroup/cgroup-v1.c
> @@ -681,11 +681,14 @@ int proc_cgroupstats_show(struct seq_file *m, void *v)
>   	 * cgroup_mutex contention.
>   	 */
>   
> -	for_each_subsys(ss, i)
> +	for_each_subsys(ss, i) {
> +		if (cgroup1_subsys_absent(ss))
> +			continue;
>   		seq_printf(m, "%s\t%d\t%d\t%d\n",
>   			   ss->legacy_name, ss->root->hierarchy_id,
>   			   atomic_read(&ss->root->nr_cgrps),
>   			   cgroup_ssid_enabled(i));
> +	}
>   
>   	return 0;
>   }
Reviewed-by: Waiman Long <longman@redhat.com>