diff options
author | Tejun Heo <tj@kernel.org> | 2015-11-20 20:55:52 (GMT) |
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committer | Tejun Heo <tj@kernel.org> | 2015-11-20 20:55:52 (GMT) |
commit | 16af439645455fbf36984ca5e72f31073ee19ab7 (patch) | |
tree | c63b8ea7f219c1c9c2d0508ceb5f8abc78f231a4 /kernel | |
parent | bd96f76a2454c6b97d70945902e30b4c31510678 (diff) | |
download | linux-16af439645455fbf36984ca5e72f31073ee19ab7.tar.xz |
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')
-rw-r--r-- | kernel/cgroup.c | 39 |
1 files changed, 34 insertions, 5 deletions
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) |