[PATCH] cgroup.c: add helper __cset_cgroup_from_root to cleanup duplicated codes

From: Lin Feng
Date: Thu Jun 16 2022 - 06:39:27 EST


No funtionality change, but save us some lines.

Signed-off-by: Lin Feng <linf@xxxxxxxxxx>
---
kernel/cgroup/cgroup.c | 58 ++++++++++++++++++++----------------------
1 file changed, 27 insertions(+), 31 deletions(-)

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 1779ccddb734..a8a46eb66f21 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1376,6 +1376,31 @@ static void cgroup_destroy_root(struct cgroup_root *root)
cgroup_free_root(root);
}

+static inline struct cgroup *__cset_cgroup_from_root(struct css_set *cset,
+ struct cgroup_root *root)
+{
+ struct cgroup *res_cgroup = NULL;
+
+ if (cset == &init_css_set) {
+ res_cgroup = &root->cgrp;
+ } else if (root == &cgrp_dfl_root) {
+ res_cgroup = cset->dfl_cgrp;
+ } else {
+ struct cgrp_cset_link *link;
+
+ list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
+ struct cgroup *c = link->cgrp;
+
+ if (c->root == root) {
+ res_cgroup = c;
+ break;
+ }
+ }
+ }
+
+ return res_cgroup;
+}
+
/*
* look up cgroup associated with current task's cgroup namespace on the
* specified hierarchy
@@ -1391,22 +1416,8 @@ current_cgns_cgroup_from_root(struct cgroup_root *root)
rcu_read_lock();

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;
-
- list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
- struct cgroup *c = link->cgrp;
+ res = __cset_cgroup_from_root(cset, root);

- if (c->root == root) {
- res = c;
- break;
- }
- }
- }
rcu_read_unlock();

BUG_ON(!res);
@@ -1422,22 +1433,7 @@ static struct cgroup *cset_cgroup_from_root(struct css_set *cset,
lockdep_assert_held(&cgroup_mutex);
lockdep_assert_held(&css_set_lock);

- if (cset == &init_css_set) {
- res = &root->cgrp;
- } else if (root == &cgrp_dfl_root) {
- res = cset->dfl_cgrp;
- } else {
- struct cgrp_cset_link *link;
-
- list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
- struct cgroup *c = link->cgrp;
-
- if (c->root == root) {
- res = c;
- break;
- }
- }
- }
+ res = __cset_cgroup_from_root(cset, root);

BUG_ON(!res);
return res;
--
2.31.1