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Commit e406d1cf authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: reimplement cgroup_transfer_tasks() without using css_scan_tasks() 



Reimplement cgroup_transfer_tasks() so that it repeatedly fetches the
first task in the cgroup and then tranfers it.  This achieves the same
result without using css_scan_tasks() which is scheduled to be
removed.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent 07bc356e

kernel/cgroup.c

+20 −11
Original line number Diff line number Diff line
@@ -2850,15 +2850,6 @@ int css_scan_tasks(struct cgroup_subsys_state *css, 
	return 0;

}



static void cgroup_transfer_one_task(struct task_struct *task, void *data)

{

	struct cgroup *new_cgroup = data;



	mutex_lock(&cgroup_mutex);

	cgroup_attach_task(new_cgroup, task, false);

	mutex_unlock(&cgroup_mutex);

}



/**

 * cgroup_trasnsfer_tasks - move tasks from one cgroup to another

 * @to: cgroup to which the tasks will be moved
@@ -2866,8 +2857,26 @@ static void cgroup_transfer_one_task(struct task_struct *task, void *data) 
 */

int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)

{

	return css_scan_tasks(&from->dummy_css, NULL, cgroup_transfer_one_task,

			      to, NULL);

	struct css_task_iter it;

	struct task_struct *task;

	int ret = 0;



	do {

		css_task_iter_start(&from->dummy_css, &it);

		task = css_task_iter_next(&it);

		if (task)

			get_task_struct(task);

		css_task_iter_end(&it);



		if (task) {

			mutex_lock(&cgroup_mutex);

			ret = cgroup_attach_task(to, task, false);

			mutex_unlock(&cgroup_mutex);

			put_task_struct(task);

		}

	} while (task && !ret);



	return ret;

}



/*