Currently, the function task_under_cgroup_hierarchy() allows us to
determine if a task resides exclusively within a cgroup2 hierarchy.
Nevertheless, given the continued prevalence of cgroup1, it's useful that
we make a minor adjustment to extend its functionality to cgroup1 as well.
Once this modification is implemented, we will have the ability to
effortlessly verify a task's cgroup membership within BPF programs. For
instance, we can easily check if a task belongs to a cgroup1 directory,
such as /sys/fs/cgroup/cpu,cpuacct/kubepods/burstable/ or
/sys/fs/cgroup/cpu,cpuacct/kubepods/besteffort/.
Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
---
include/linux/cgroup.h | 24 +++++++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index b307013..5414a2c 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -543,15 +543,33 @@ static inline struct cgroup *cgroup_ancestor(struct cgroup *cgrp,
* @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.
+ * It follows all the same rules as cgroup_is_descendant.
*/
static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
struct cgroup *ancestor)
{
struct css_set *cset = task_css_set(task);
+ struct cgroup *cgrp;
+ bool ret = false;
+ int ssid;
+
+ if (ancestor->root == &cgrp_dfl_root)
+ return cgroup_is_descendant(cset->dfl_cgrp, ancestor);
+
+ for (ssid = 0; ssid < CGROUP_SUBSYS_COUNT; ssid++) {
+ if (!ancestor->subsys[ssid])
+ continue;
- return cgroup_is_descendant(cset->dfl_cgrp, ancestor);
+ cgrp = task_css(task, ssid)->cgroup;
+ if (!cgrp)
+ continue;
+
+ if (!cgroup_is_descendant(cgrp, ancestor))
+ return false;
+ if (!ret)
+ ret = true;
+ }
+ return ret;
}
/* no synchronization, the result can only be used as a hint */
--
1.8.3.1
