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@xxxxxxxxxx>
---
kernel/cgroup.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 51632b4..17c8985 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1013,13 +1013,6 @@ static int rebind_subsystems(struct cgroupfs_root *root,
if (test_bit(i, &added_mask) && ss->root != &cgroup_dummy_root)
return -EBUSY;
- /* 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;
@@ -1365,6 +1358,12 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data)
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;
--
1.8.3.1
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