1 files changed, 28 insertions, 30 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index cbbb46f783de..dffa54041d4a 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;