From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754871Ab3DODuW (ORCPT ); Sun, 14 Apr 2013 23:50:22 -0400 Received: from mail-da0-f50.google.com ([209.85.210.50]:39733 "EHLO mail-da0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753595Ab3DODuV (ORCPT ); Sun, 14 Apr 2013 23:50:21 -0400 Date: Sun, 14 Apr 2013 20:50:08 -0700 From: Tejun Heo To: lizefan@huawei.com Cc: containers@lists.linux-foundation.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kay@vrfy.org, greg@kroah.com, lennart@poettering.net, daniel@zonque.org Subject: [PATCH UPDATED 4/4] cgroup: implement task_cgroup_path_from_hierarchy() Message-ID: <20130415035008.GM3050@htj.dyndns.org> References: <1365964619-14762-1-git-send-email-tj@kernel.org> <1365964619-14762-5-git-send-email-tj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1365964619-14762-5-git-send-email-tj@kernel.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org kdbus folks want a sane way to determine the cgroup path that a given task belongs to on a given hierarchy, which is a reasonble thing to expect from cgroup core. Implement task_cgroup_path_from_hierarchy(). v2: Dropped unnecessary NULL check on the return value of task_cgroup_from_root() as suggested by Li Zefan. Signed-off-by: Tejun Heo Acked-by: Greg Kroah-Hartman Acked-by: Li Zefan Cc: Kay Sievers Cc: Lennart Poettering Cc: Daniel Mack --- include/linux/cgroup.h | 2 ++ kernel/cgroup.c | 32 ++++++++++++++++++++++++++++++++ 2 files changed, 34 insertions(+) --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -443,6 +443,8 @@ int cgroup_is_removed(const struct cgrou bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor); int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen); +int task_cgroup_path_from_hierarchy(struct task_struct *task, int hierarchy_id, + char *buf, size_t buflen); int cgroup_task_count(const struct cgroup *cgrp); --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1842,6 +1842,38 @@ out: } EXPORT_SYMBOL_GPL(cgroup_path); +/** + * task_cgroup_path_from_hierarchy - cgroup path of a task on a hierarchy + * @task: target task + * @hierarchy_id: the hierarchy to look up @task's cgroup from + * @buf: the buffer to write the path into + * @buflen: the length of the buffer + * + * Determine @task's cgroup on the hierarchy specified by @hierarchy_id and + * copy its path into @buf. This function grabs cgroup_mutex and shouldn't + * be used inside locks used by cgroup controller callbacks. + */ +int task_cgroup_path_from_hierarchy(struct task_struct *task, int hierarchy_id, + char *buf, size_t buflen) +{ + struct cgroupfs_root *root; + struct cgroup *cgrp = NULL; + int ret = -ENOENT; + + mutex_lock(&cgroup_mutex); + + root = idr_find(&cgroup_hierarchy_idr, hierarchy_id); + if (root) { + cgrp = task_cgroup_from_root(task, root); + ret = cgroup_path(cgrp, buf, buflen); + } + + mutex_unlock(&cgroup_mutex); + + return ret; +} +EXPORT_SYMBOL_GPL(task_cgroup_path_from_hierarchy); + /* * Control Group taskset */