From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH 3/8] cgroup: implement cgroup_get_from_path() and expose cgroup_put() Date: Mon, 7 Dec 2015 17:38:50 -0500 Message-ID: <1449527935-27056-4-git-send-email-tj@kernel.org> References: <1449527935-27056-1-git-send-email-tj@kernel.org> Cc: lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netfilter-devel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, coreteam-Cap9r6Oaw4JrovVCs/uTlw@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kernel-team-b10kYP2dOMg@public.gmane.org, ninasc-b10kYP2dOMg@public.gmane.org, Tejun Heo To: davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org, pablo-Cap9r6Oaw4JrovVCs/uTlw@public.gmane.org, kaber-dcUjhNyLwpNeoWH0uzbU5w@public.gmane.org, kadlec-K40Dz/62t/MgiyqX0sVFJYdd74u8MsAO@public.gmane.org, daniel-FeC+5ew28dpmcu3hnIyYJQ@public.gmane.org, daniel.wagner-98C5kh4wR6ohFhg+JK9F0w@public.gmane.org, nhorman-2XuSBdqkA4R54TAoqtyWWQ@public.gmane.org Return-path: In-Reply-To: <1449527935-27056-1-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org Implement cgroup_get_from_path() using kernfs_walk_and_get() which obtains a default hierarchy cgroup from its path. This will be used to allow cgroup path based matching from outside cgroup proper - e.g. networking and perf. v2: Add EXPORT_SYMBOL_GPL(cgroup_get_from_path). Signed-off-by: Tejun Heo --- include/linux/cgroup.h | 7 +++++++ kernel/cgroup.c | 39 ++++++++++++++++++++++++++++++++++----- 2 files changed, 41 insertions(+), 5 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index b5ee2c4..4c3ffab 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -81,6 +81,8 @@ struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgroup, struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry, struct cgroup_subsys *ss); +struct cgroup *cgroup_get_from_path(const char *path); + int cgroup_attach_task_all(struct task_struct *from, struct task_struct *); int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from); @@ -351,6 +353,11 @@ static inline void css_put_many(struct cgroup_subsys_state *css, unsigned int n) percpu_ref_put_many(&css->refcnt, n); } +static inline void cgroup_put(struct cgroup *cgrp) +{ + css_put(&cgrp->self); +} + /** * task_css_set_check - obtain a task's css_set with extra access conditions * @task: the task to obtain css_set for diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 3190040..3db5e8f 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -434,11 +434,6 @@ static bool cgroup_tryget(struct cgroup *cgrp) return css_tryget(&cgrp->self); } -static void cgroup_put(struct cgroup *cgrp) -{ - css_put(&cgrp->self); -} - struct cgroup_subsys_state *of_css(struct kernfs_open_file *of) { struct cgroup *cgrp = of->kn->parent->priv; @@ -5753,6 +5748,40 @@ struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss) return id > 0 ? idr_find(&ss->css_idr, id) : NULL; } +/** + * cgroup_get_from_path - lookup and get a cgroup from its default hierarchy path + * @path: path on the default hierarchy + * + * Find the cgroup at @path on the default hierarchy, increment its + * reference count and return it. Returns pointer to the found cgroup on + * success, ERR_PTR(-ENOENT) if @path doens't exist and ERR_PTR(-ENOTDIR) + * if @path points to a non-directory. + */ +struct cgroup *cgroup_get_from_path(const char *path) +{ + struct kernfs_node *kn; + struct cgroup *cgrp; + + mutex_lock(&cgroup_mutex); + + kn = kernfs_walk_and_get(cgrp_dfl_root.cgrp.kn, path); + if (kn) { + if (kernfs_type(kn) == KERNFS_DIR) { + cgrp = kn->priv; + cgroup_get(cgrp); + } else { + cgrp = ERR_PTR(-ENOTDIR); + } + kernfs_put(kn); + } else { + cgrp = ERR_PTR(-ENOENT); + } + + mutex_unlock(&cgroup_mutex); + return cgrp; +} +EXPORT_SYMBOL_GPL(cgroup_get_from_path); + #ifdef CONFIG_CGROUP_DEBUG static struct cgroup_subsys_state * debug_css_alloc(struct cgroup_subsys_state *parent_css) -- 2.5.0