Re: [PATCH 1/9 v3] cgroup: add cgroup_subsys->post_create()

From: Li Zefan
Date: Fri Nov 09 2012 - 04:09:54 EST


On 2012/11/9 3:07, Tejun Heo wrote:
> Subject: cgroup: add cgroup_subsys->post_create()
>
> Currently, there's no way for a controller to find out whether a new
> cgroup finished all ->create() allocatinos successfully and is
> considered "live" by cgroup.
>
> This becomes a problem later when we add generic descendants walking
> to cgroup which can be used by controllers as controllers don't have a
> synchronization point where it can synchronize against new cgroups
> appearing in such walks.
>
> This patch adds ->post_create(). It's called after all ->create()
> succeeded and the cgroup is linked into the generic cgroup hierarchy.
> This plays the counterpart of ->pre_destroy().
>
> When used in combination with the to-be-added generic descendant
> iterators, ->post_create() can be used to implement reliable state
> inheritance. It will be explained with the descendant iterators.
>
> v2: Added a paragraph about its future use w/ descendant iterators per
> Michal.
>
> v3: Forgot to add ->post_create() invocation to cgroup_load_subsys().
> Fixed.
>
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Acked-by: Michal Hocko <mhocko@xxxxxxx>
> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> Cc: Glauber Costa <glommer@xxxxxxxxxxxxx>

Li Zefan <lizefan@xxxxxxxxxx

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