Re: [PATCH 1/5] cgroup: ID notification call back

From: Li Zefan
Date: Tue Aug 24 2010 - 05:00:13 EST


KAMEZAWA Hiroyuki wrote:
> CC'ed to Paul Menage and Li Zefan.
> ==
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
>
> When cgroup subsystem use ID (ss->use_id==1), each css's ID is assigned
> after successful call of ->create(). css_ID is tightly coupled with
> css struct itself but it is allocated by ->create() call, IOW,
> per-subsystem special allocations.
>
> To know css_id before creation, this patch adds id_attached() callback.
> after css_ID allocation. This will be used by memory cgroup's quick lookup
> routine.
>
> Maybe you can think of other implementations as
> - pass ID to ->create()
> or
> - add post_create()
> etc...
> But when considering dirtiness of codes, this straightforward patch seems
> good to me. If someone wants post_create(), this patch can be replaced.
>
> Changelog: 20100820
> - new approarch.
>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>

Acked-by: Li Zefan <lizf@xxxxxxxxxxxxxx>

...
>
> Index: mmotm-0811/include/linux/cgroup.h
> ===================================================================
> --- mmotm-0811.orig/include/linux/cgroup.h
> +++ mmotm-0811/include/linux/cgroup.h
> @@ -475,6 +475,7 @@ struct cgroup_subsys {
> struct cgroup *cgrp);
> void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp);
> void (*bind)(struct cgroup_subsys *ss, struct cgroup *root);
> + void (*id_attached)(struct cgroup_subsys *ss, struct cgroup *cgrp);

Maybe pass the id number to id_attached() is better.

And actually the @ss argument is not necessary, because the memcg's
id_attached() handler of course knows it's dealing with the memory
cgroup subsystem.

So I suspect we can just remove all the @ss from all the callbacks..

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