cgroup: move number_of_cgroups test out of rebind_subsystems() into cgroup_remount()
rebind_subsystems() currently fails if the hierarchy has any !root
cgroups; however, on the planned unified hierarchy,
rebind_subsystems() will be used while populated. Move the test to
cgroup_remount(), which is the only place the test is necessary
anyway.
As it's impossible for the other two callers of rebind_subsystems() to
have populated hierarchy, this doesn't make any behavior 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 4ec8d2da..c108d3d 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1021,13 +1021,6 @@
}
}
- /* Currently we don't handle adding/removing subsystems when
- * any child cgroups exist. This is theoretically supportable
- * but involves complex error handling, so it's being left until
- * later */
- if (root->number_of_cgroups > 1)
- return -EBUSY;
-
ret = cgroup_populate_dir(cgrp, added_mask);
if (ret)
return ret;
@@ -1373,6 +1366,12 @@
goto out_unlock;
}
+ /* remounting is not allowed for populated hierarchies */
+ if (root->number_of_cgroups > 1) {
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+
ret = rebind_subsystems(root, added_mask, removed_mask);
if (ret)
goto out_unlock;