From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kamezawa Hiroyuki Subject: Re: [PATCH 1/9 v2] cgroup: add cgroup_subsys->post_create() Date: Thu, 08 Nov 2012 11:59:41 +0900 Message-ID: <509B201D.3060909@jp.fujitsu.com> References: <1351931915-1701-1-git-send-email-tj@kernel.org> <1351931915-1701-2-git-send-email-tj@kernel.org> <20121107171508.GF2660@mtj.dyndns.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20121107171508.GF2660-9pTldWuhBndy/B6EtB590w@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Tejun Heo Cc: lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, 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 (2012/11/08 2:15), Tejun Heo wrote: > 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. > > Signed-off-by: Tejun Heo > Acked-by: Michal Hocko > Cc: Glauber Costa Reviewed-by: KAMEZAWA Hiroyuki