diff options
| author | Li Zefan <lizefan@huawei.com> | 2013-07-31 09:51:31 +0800 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2013-07-31 07:47:34 -0400 |
| commit | e14880f7bb7e0dc0933af304998371dd543ceb40 (patch) | |
| tree | d17af9f967acdce1761264a2361986f10348995e | |
| parent | b414dc09a31d41d696093a4cce9fb2853a5ecd4e (diff) | |
cgroup: implement cgroup_from_id()
This will be used as a replacement for css_lookup().
There's a difference with cgroup id and css id. cgroup id starts with 0,
while css id starts with 1.
v4:
- also check if cggroup_mutex is held.
- make it an inline function.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Tejun Heo <tj@kernel.org>
| -rw-r--r-- | include/linux/cgroup.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 4dfcd0e1b73..bbf4d89b56a 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -720,6 +720,24 @@ static inline struct cgroup* task_cgroup(struct task_struct *task, return task_subsys_state(task, subsys_id)->cgroup; } +/** + * cgroup_from_id - lookup cgroup by id + * @ss: cgroup subsys to be looked into + * @id: the cgroup id + * + * Returns the cgroup if there's valid one with @id, otherwise returns NULL. + * Should be called under rcu_read_lock(). + */ +static inline struct cgroup *cgroup_from_id(struct cgroup_subsys *ss, int id) +{ +#ifdef CONFIG_PROVE_RCU + rcu_lockdep_assert(rcu_read_lock_held() || + lockdep_is_held(&cgroup_mutex), + "cgroup_from_id() needs proper protection"); +#endif + return idr_find(&ss->root->cgroup_idr, id); +} + struct cgroup *cgroup_next_sibling(struct cgroup *pos); /** |