+/**
+ * task_under_cgroup_hierarchy - test task's membership of cgroup ancestry
+ * @task: the task to be tested
+ * @ancestor: possible ancestor of @task's cgroup
+ *
+ * Tests whether @task's default cgroup hierarchy is a descendant of @ancestor.
+ * It follows all the same rules as cgroup_is_descendant, and only applies
+ * to the default hierarchy.
+ */
+static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
+ struct cgroup *ancestor)
+{
+ struct css_set *cset = task_css_set(task);
+
+ return cgroup_is_descendant(cset->dfl_cgrp, ancestor);
+}
+