netdev - [PATCH bpf-next v3 11/13] mm, memcg: Add new helper task_under_memcg

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Date:   Fri,  2 Sep 2022 02:30:01 +0000
From:   Yafang Shao <laoar.shao@...il.com>
To:     ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
        kafai@...com, songliubraving@...com, yhs@...com,
        john.fastabend@...il.com, kpsingh@...nel.org, sdf@...gle.com,
        haoluo@...gle.com, jolsa@...nel.org, hannes@...xchg.org,
        mhocko@...nel.org, roman.gushchin@...ux.dev, shakeelb@...gle.com,
        songmuchun@...edance.com, akpm@...ux-foundation.org, tj@...nel.org,
        lizefan.x@...edance.com
Cc:     cgroups@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-mm@...ck.org,
        Yafang Shao <laoar.shao@...il.com>
Subject: [PATCH bpf-next v3 11/13] mm, memcg: Add new helper task_under_memcg_hierarchy

Introduce a new helper to check if a task belongs to a specific memcg.
It is similar to mm_match_cgroup() except that the new helper is checked
against a task rather than a mm struct. So with this new helper we can
check a task directly.

Signed-off-by: Yafang Shao <laoar.shao@...il.com>
---
 include/linux/memcontrol.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 7a7f252..3b8a8dd 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -887,6 +887,20 @@ static inline bool mem_cgroup_is_descendant(struct mem_cgroup *memcg,
 	return cgroup_is_descendant(memcg->css.cgroup, root->css.cgroup);
 }
 
+static inline bool task_under_memcg_hierarchy(struct task_struct *p,
+					      struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *task_memcg;
+	bool match = false;
+
+	rcu_read_lock();
+	task_memcg = mem_cgroup_from_task(p);
+	if (task_memcg)
+		match = mem_cgroup_is_descendant(task_memcg, memcg);
+	rcu_read_unlock();
+	return match;
+}
+
 static inline bool mm_match_cgroup(struct mm_struct *mm,
 				   struct mem_cgroup *memcg)
 {
-- 
1.8.3.1