From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758845Ab3GaBvu (ORCPT ); Tue, 30 Jul 2013 21:51:50 -0400 Received: from szxga01-in.huawei.com ([119.145.14.64]:42167 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755477Ab3GaBvs (ORCPT ); Tue, 30 Jul 2013 21:51:48 -0400 Message-ID: <51F86D8A.4060201@huawei.com> Date: Wed, 31 Jul 2013 09:51:06 +0800 From: Li Zefan User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/20130620 Thunderbird/17.0.7 MIME-Version: 1.0 To: Tejun Heo CC: Andrew Morton , KAMEZAWA Hiroyuki , Michal Hocko , Johannes Weiner , LKML , Cgroups , Subject: [PATCH v4 2/8] cgroup: document how cgroup IDs are assigned References: <51F86D69.2030907@huawei.com> In-Reply-To: <51F86D69.2030907@huawei.com> Content-Type: text/plain; charset="GB2312" 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 As cgroup id has been used in netprio cgroup and will be used in memcg, it's important to make it clear how a cgroup id is allocated. For example, in netprio cgroup, the id is used as index of anarray. Signed-off-by: Li Zefan Reviewed-by: Michal Hocko --- include/linux/cgroup.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 2bd052d..8c107e9 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -161,7 +161,13 @@ struct cgroup_name { struct cgroup { unsigned long flags; /* "unsigned long" so bitops work */ - int id; /* idr allocated in-hierarchy ID */ + /* + * idr allocated in-hierarchy ID. + * + * The ID of the root cgroup is always 0, and a new cgroup + * will be assigned with a smallest available ID. + */ + int id; /* * We link our 'sibling' struct into our parent's 'children'. -- 1.8.0.2