cgroup: short-circuit current_cgns_cgroup_from_root() on the default hierarchy

Like commit 13d82fb77abb ("cgroup: short-circuit cset_cgroup_from_root() on
the default hierarchy"), short-circuit current_cgns_cgroup_from_root() on
the default hierarchy.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 080561bb8a4b7f8ddf890bde14f6fc6a349b3585..f6cba23290a133c09e1d98481609244bb72092a2 100644 (file)
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1374,6 +1374,8 @@ current_cgns_cgroup_from_root(struct cgroup_root *root)
        cset = current->nsproxy->cgroup_ns->root_cset;
        if (cset == &init_css_set) {
                res = &root->cgrp;
+       } else if (root == &cgrp_dfl_root) {
+               res = cset->dfl_cgrp;
        } else {
                struct cgrp_cset_link *link;