1 files changed, 28 insertions, 30 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index cbbb46f..dffa540 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2705,36 +2705,6 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
 				ret = -ENOENT;
 				goto out_unlock;
 			}
-
-			/*
-			 * @ss is already enabled through dependency and
-			 * we'll just make it visible.  Skip draining.
-			 */
-			if (cgrp->child_subsys_mask & (1 << ssid))
-				continue;
-
-			/*
-			 * Because css offlining is asynchronous, userland
-			 * might try to re-enable the same controller while
-			 * the previous instance is still around.  In such
-			 * cases, wait till it's gone using offline_waitq.
-			 */
-			cgroup_for_each_live_child(child, cgrp) {
-				DEFINE_WAIT(wait);
-
-				if (!cgroup_css(child, ss))
-					continue;
-
-				cgroup_get(child);
-				prepare_to_wait(&child->offline_waitq, &wait,
-						TASK_UNINTERRUPTIBLE);
-				cgroup_kn_unlock(of->kn);
-				schedule();
-				finish_wait(&child->offline_waitq, &wait);
-				cgroup_put(child);
-
-				return restart_syscall();
-			}
 		} else if (disable & (1 << ssid)) {
 			if (!(cgrp->subtree_control & (1 << ssid))) {
 				disable &= ~(1 << ssid);
@@ -2780,6 +2750,34 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
 	enable |= css_enable;
 	disable |= css_disable;
 
+	/*
+	 * Because css offlining is asynchronous, userland might try to
+	 * re-enable the same controller while the previous instance is
+	 * still around.  In such cases, wait till it's gone using
+	 * offline_waitq.
+	 */
+	for_each_subsys(ss, ssid) {
+		if (!(css_enable & (1 << ssid)))
+			continue;
+
+		cgroup_for_each_live_child(child, cgrp) {
+			DEFINE_WAIT(wait);
+
+			if (!cgroup_css(child, ss))
+				continue;
+
+			cgroup_get(child);
+			prepare_to_wait(&child->offline_waitq, &wait,
+					TASK_UNINTERRUPTIBLE);
+			cgroup_kn_unlock(of->kn);
+			schedule();
+			finish_wait(&child->offline_waitq, &wait);
+			cgroup_put(child);
+
+			return restart_syscall();
+		}
+	}
+
 	cgrp->subtree_control = new_sc;
 	cgrp->child_subsys_mask = new_ss;