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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752099Ab2KIJKe (ORCPT ); Fri, 9 Nov 2012 04:10:34 -0500 Received: from szxga01-in.huawei.com ([119.145.14.64]:35483 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751948Ab2KIJKC (ORCPT ); Fri, 9 Nov 2012 04:10:02 -0500 Message-ID: <509CC85F.8030607@huawei.com> Date: Fri, 9 Nov 2012 17:09:51 +0800 From: Li Zefan User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:16.0) Gecko/20121010 Thunderbird/16.0.1 MIME-Version: 1.0 To: Tejun Heo CC: , , , , , , , Glauber Costa Subject: Re: [PATCH 1/9 v3] cgroup: add cgroup_subsys->post_create() References: <1351931915-1701-1-git-send-email-tj@kernel.org> <1351931915-1701-2-git-send-email-tj@kernel.org> <20121108190715.GD9672@htj.dyndns.org> In-Reply-To: <20121108190715.GD9672@htj.dyndns.org> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.135.68.215] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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