On Thu, May 4, 2023 at 11:08 PM Feng zhou <zhoufeng.zf@xxxxxxxxxxxxx> wrote:
<...>
---
kernel/bpf/helpers.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index bb6b4637ebf2..453cbd312366 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2149,6 +2149,25 @@ __bpf_kfunc struct cgroup *bpf_cgroup_from_id(u64 cgid)
return NULL;
return cgrp;
}
+
+/**
+ * bpf_task_under_cgroup - wrap task_under_cgroup_hierarchy() as a kfunc, 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.
+ */
+__bpf_kfunc long bpf_task_under_cgroup(struct task_struct *task,
+ struct cgroup *ancestor)
+{
+ if (unlikely(!ancestor || !task))
+ return -EINVAL;
+
+ return task_under_cgroup_hierarchy(task, ancestor);
+}
#endif /* CONFIG_CGROUPS */
I wonder in what situation a null 'task' or 'ancestor' can be passed.
Please call out in the comment that the returned value can be a
negative error, so that writing if(bpf_task_under_cgroup()) may cause
surprising results.
Hao