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Commit ceb6a081 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: separate out cset_group_from_root() from task_cgroup_from_root() 



This will be used by the planned migration path update.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent b3dc094e

kernel/cgroup.c

+17 −12
Original line number Diff line number Diff line
@@ -758,25 +758,15 @@ static void cgroup_destroy_root(struct cgroupfs_root *root) 
	cgroup_free_root(root);

}



/*

 * Return the cgroup for "task" from the given hierarchy. Must be

 * called with cgroup_mutex and css_set_rwsem held.

 */

static struct cgroup *task_cgroup_from_root(struct task_struct *task,

/* look up cgroup associated with given css_set on the specified hierarchy */

static struct cgroup *cset_cgroup_from_root(struct css_set *cset,

					    struct cgroupfs_root *root)

{

	struct css_set *cset;

	struct cgroup *res = NULL;



	lockdep_assert_held(&cgroup_mutex);

	lockdep_assert_held(&css_set_rwsem);



	/*

	 * No need to lock the task - since we hold cgroup_mutex the

	 * task can't change groups, so the only thing that can happen

	 * is that it exits and its css is set back to init_css_set.

	 */

	cset = task_css_set(task);

	if (cset == &init_css_set) {

		res = &root->top_cgroup;

	} else {
@@ -796,6 +786,21 @@ static struct cgroup *task_cgroup_from_root(struct task_struct *task, 
	return res;

}



/*

 * Return the cgroup for "task" from the given hierarchy. Must be

 * called with cgroup_mutex and css_set_rwsem held.

 */

static struct cgroup *task_cgroup_from_root(struct task_struct *task,

					    struct cgroupfs_root *root)

{

	/*

	 * No need to lock the task - since we hold cgroup_mutex the

	 * task can't change groups, so the only thing that can happen

	 * is that it exits and its css is set back to init_css_set.

	 */

	return cset_cgroup_from_root(task_css_set(task), root);

}



/*

 * There is one global cgroup mutex. We also require taking

 * task_lock() when dereferencing a task's cgroup subsys pointers.