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: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 580d348..8afddb1 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2583,6 +2583,10 @@
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 @@
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 @@
(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 @@
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 @@
if (!enable && !disable) {
ret = 0;
- goto out_unlock_tree;
- }
-
- if (!cgroup_lock_live_group(cgrp)) {
- ret = -ENODEV;
- goto out_unlock_tree;
+ goto out_unlock;
}
/*