From mboxrd@z Thu Jan 1 00:00:00 1970 From: serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org Subject: [PATCH 3/8] cgroup: add function to get task's cgroup Date: Mon, 16 Nov 2015 13:51:40 -0600 Message-ID: <1447703505-29672-4-git-send-email-serge@hallyn.com> References: <1447703505-29672-1-git-send-email-serge@hallyn.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1447703505-29672-1-git-send-email-serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org, lxc-devel-cunTk1MwBs9qMoObBWhMNEqPaTDuhLve2LY78lusg7I@public.gmane.org, tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org List-Id: linux-api@vger.kernel.org From: Aditya Kali get_task_cgroup() returns the (reference counted) cgroup of the given task. Signed-off-by: Aditya Kali Acked-by: Serge Hallyn --- include/linux/cgroup.h | 1 + kernel/cgroup.c | 25 +++++++++++++++++++++++++ 2 files changed, 26 insertions(+) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 22e3754..29f0b02 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -326,6 +326,7 @@ static inline bool css_tryget_online(struct cgroup_subsys_state *css) return percpu_ref_tryget_live(&css->refcnt); return true; } +struct cgroup *get_task_cgroup(struct task_struct *task); /** * css_put - put a css reference diff --git a/kernel/cgroup.c b/kernel/cgroup.c index f1603c1..e29c346 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2210,6 +2210,31 @@ char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) } EXPORT_SYMBOL_GPL(task_cgroup_path); +/* + * get_task_cgroup - returns the cgroup of the task in the default cgroup + * hierarchy. + * + * @task: target task + * This function returns the @task's cgroup on the default cgroup hierarchy. The + * returned cgroup has its reference incremented (by calling cgroup_get()). So + * the caller must cgroup_put() the obtained reference once it is done with it. + */ +struct cgroup *get_task_cgroup(struct task_struct *task) +{ + struct cgroup *cgrp; + + mutex_lock(&cgroup_mutex); + spin_lock_bh(&css_set_lock); + + cgrp = task_cgroup_from_root(task, &cgrp_dfl_root); + cgroup_get(cgrp); + + spin_unlock_bh(&css_set_lock); + mutex_unlock(&cgroup_mutex); + return cgrp; +} +EXPORT_SYMBOL_GPL(get_task_cgroup); + /* used to track tasks and other necessary states during migration */ struct cgroup_taskset { /* the src and dst cset list running through cset->mg_node */ -- 1.7.9.5