Re: [PATCH] cgroup: Drop sock_cgroup_classid() dummy implementation

[Waiman Long <llong@redhat.com>]

On 6/3/25 11:45 AM, Michal Koutný wrote:
> The semantic of returning 0 is unclear when !CONFIG_CGROUP_NET_CLASSID.
> Since there are no callers of sock_cgroup_classid() with that config
> anymore we can undefine the helper at all and enforce all (future)
> callers to handle cases when !CONFIG_CGROUP_NET_CLASSID.

That statement is correct with the current upstream kernel.

Reviewed-by: Waiman Long <longman@redhat.com>

> Signed-off-by: Michal Koutný <mkoutny@suse.com>
> Link: https://lore.kernel.org/r/Z_52r_v9-3JUzDT7@calendula/
> Acked-by: Tejun Heo <tj@kernel.org>
> ---
>   include/linux/cgroup-defs.h | 10 ++++------
>   1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
> index e61687d5e496d..cd7f093e34cd7 100644
> --- a/include/linux/cgroup-defs.h
> +++ b/include/linux/cgroup-defs.h
> @@ -898,14 +898,12 @@ static inline u16 sock_cgroup_prioidx(const struct sock_cgroup_data *skcd)
>   #endif
>   }
>   
> +#ifdef CONFIG_CGROUP_NET_CLASSID
>   static inline u32 sock_cgroup_classid(const struct sock_cgroup_data *skcd)
>   {
> -#ifdef CONFIG_CGROUP_NET_CLASSID
>   	return READ_ONCE(skcd->classid);
> -#else
> -	return 0;
> -#endif
>   }
> +#endif
>   
>   static inline void sock_cgroup_set_prioidx(struct sock_cgroup_data *skcd,
>   					   u16 prioidx)
> @@ -915,13 +913,13 @@ static inline void sock_cgroup_set_prioidx(struct sock_cgroup_data *skcd,
>   #endif
>   }
>   
> +#ifdef CONFIG_CGROUP_NET_CLASSID
>   static inline void sock_cgroup_set_classid(struct sock_cgroup_data *skcd,
>   					   u32 classid)
>   {
> -#ifdef CONFIG_CGROUP_NET_CLASSID
>   	WRITE_ONCE(skcd->classid, classid);
> -#endif
>   }
> +#endif
>   
>   #else	/* CONFIG_SOCK_CGROUP_DATA */
>   
>
> base-commit: cd2e103d57e5615f9bb027d772f93b9efd567224