From mboxrd@z Thu Jan 1 00:00:00 1970 From: Li Zefan Subject: Re: [PATCH 1/9 v3] cgroup: add cgroup_subsys->post_create() Date: Fri, 9 Nov 2012 17:09:51 +0800 Message-ID: <509CC85F.8030607@huawei.com> References: <1351931915-1701-1-git-send-email-tj@kernel.org> <1351931915-1701-2-git-send-email-tj@kernel.org> <20121108190715.GD9672@htj.dyndns.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20121108190715.GD9672-Gd/HAXX7CRxy/B6EtB590w@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Tejun Heo Cc: mhocko-AlSwsSmVLrQ@public.gmane.org, rjw-KKrjLPT3xs0@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, fweisbec-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, Glauber Costa 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 > Acked-by: Michal Hocko > Reviewed-by: KAMEZAWA Hiroyuki > Cc: Glauber Costa Acked-by: Li Zefan