cgroup: implement cgroup_from_id() (e14880f7) · Commits · 戴 / test

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>

include/linux/cgroup.h

+18 −0

Original line number	Diff line number	Diff line
		@@ -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);

		/**

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