cgroup: Simplify cgroup_ancestor

Simplify cgroup_ancestor function. This is follow-up for
commit dca224f493da ("bpf: Introduce bpf_skb_ancestor_cgroup_id helper")

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 32c553556bbdc1c0d6f2db6c1fb86ddee6713367..e03a92430383d7df4de0cc894574a214f3b881c6 100644 (file)
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -567,20 +567,11 @@ static inline bool cgroup_is_descendant(struct cgroup *cgrp,
 static inline struct cgroup *cgroup_ancestor(struct cgroup *cgrp,
                                             int ancestor_level)
 {
-       struct cgroup *ptr;
-
        if (cgrp->level < ancestor_level)
                return NULL;
-
-       for (ptr = cgrp;
-            ptr && ptr->level > ancestor_level;
-            ptr = cgroup_parent(ptr))
-               ;
-
-       if (ptr && ptr->level == ancestor_level)
-               return ptr;
-
-       return NULL;
+       while (cgrp && cgrp->level > ancestor_level)
+               cgrp = cgroup_parent(cgrp);
+       return cgrp;
 }
 
 /**