From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx132.postini.com [74.125.245.132]) by kanga.kvack.org (Postfix) with SMTP id C3D346B010B for ; Mon, 8 Apr 2013 11:39:47 -0400 (EDT) Received: by mail-da0-f42.google.com with SMTP id n15so2660648dad.15 for ; Mon, 08 Apr 2013 08:39:47 -0700 (PDT) Date: Mon, 8 Apr 2013 08:39:42 -0700 From: Tejun Heo Subject: Re: [PATCH 1/8] cgroup: implement cgroup_is_ancestor() Message-ID: <20130408153942.GC3021@htj.dyndns.org> References: <51627DA9.7020507@huawei.com> <51627DBB.5050005@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51627DBB.5050005@huawei.com> Sender: owner-linux-mm@kvack.org List-ID: To: Li Zefan Cc: Andrew Morton , Glauber Costa , KAMEZAWA Hiroyuki , Michal Hocko , Johannes Weiner , LKML , Cgroups , linux-mm@kvack.org Hello, Li. On Mon, Apr 08, 2013 at 04:20:11PM +0800, Li Zefan wrote: > +/** > + * cgroup_is_ancestor - test "root" cgroup is an ancestor of "child" > + * @child: the cgroup to be tested. > + * @root: the cgroup supposed to be an ancestor of the child. Please explain locking in the comment. (I know it only requires both cgroups to be accessible but being explicit is nice.) > + * Returns true if "root" is an ancestor of "child" in its hierarchy. > + */ > +bool cgroup_is_ancestor(struct cgroup *child, struct cgroup *root) s/root/ancestor/ > +{ > + int depth = child->depth; > + > + if (depth < root->depth) > + return false; > + > + while (depth-- != root->depth) > + child = child->parent; Just walk up till it meets the ancestor or reaches root. Why bother with depth? Thanks. -- tejun -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org