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Commit ddab2b6e authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: grab cgroup_mutex earlier in cgroup_subtree_control_write() 



Move cgroup_lock_live_group() invocation upwards to right below
cgroup_tree_mutex in cgroup_subtree_control_write().  This is to help
the planned locking simplification.

This doesn't make any userland-visible behavioral changes.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent b3bfd983

kernel/cgroup.c

+8 −8
Original line number Diff line number Diff line
@@ -2583,6 +2583,10 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, 
	kernfs_break_active_protection(of->kn);



	mutex_lock(&cgroup_tree_mutex);

	if (!cgroup_lock_live_group(cgrp)) {

		ret = -ENODEV;

		goto out_unlock_tree;

	}



	for_each_subsys(ss, ssid) {

		if (enable & (1 << ssid)) {
@@ -2606,6 +2610,7 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, 
				cgroup_get(child);

				prepare_to_wait(&child->offline_waitq, &wait,

						TASK_UNINTERRUPTIBLE);

				mutex_unlock(&cgroup_mutex);

				mutex_unlock(&cgroup_tree_mutex);

				schedule();

				finish_wait(&child->offline_waitq, &wait);
@@ -2620,7 +2625,7 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, 
			    (cgrp->parent &&

			     !(cgrp->parent->child_subsys_mask & (1 << ssid)))) {

				ret = -ENOENT;

				goto out_unlock_tree;

				goto out_unlock;

			}

		} else if (disable & (1 << ssid)) {

			if (!(cgrp->child_subsys_mask & (1 << ssid))) {
@@ -2632,7 +2637,7 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, 
			cgroup_for_each_live_child(child, cgrp) {

				if (child->child_subsys_mask & (1 << ssid)) {

					ret = -EBUSY;

					goto out_unlock_tree;

					goto out_unlock;

				}

			}

		}
@@ -2640,12 +2645,7 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, 


	if (!enable && !disable) {

		ret = 0;

		goto out_unlock_tree;

	}



	if (!cgroup_lock_live_group(cgrp)) {

		ret = -ENODEV;

		goto out_unlock_tree;

		goto out_unlock;

	}



	/*