summaryrefslogtreecommitdiffstats
path: root/kernel/cgroup.c
diff options
context:
space:
mode:
authorTejun Heo <tj@kernel.org>2015-11-20 15:55:52 -0500
committerTejun Heo <tj@kernel.org>2015-11-20 15:55:52 -0500
commit16af439645455fbf36984ca5e72f31073ee19ab7 (patch)
treec63b8ea7f219c1c9c2d0508ceb5f8abc78f231a4 /kernel/cgroup.c
parentbd96f76a2454c6b97d70945902e30b4c31510678 (diff)
downloadlinux-16af439645455fbf36984ca5e72f31073ee19ab7.tar.bz2
cgroup: implement cgroup_get_from_path() and expose cgroup_put()
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 <tj@kernel.org>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c39
1 files changed, 34 insertions, 5 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 3190040792c8..3db5e8f5b702 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)