2023-05-04 03:16:48

by Feng Zhou

Subject: [PATCH bpf-next v5 1/2] bpf: Add bpf_task_under_cgroup() kfunc

From: Feng Zhou <[email protected]>

Add a kfunc that's similar to the bpf_current_task_under_cgroup.
The difference is that it is a designated task.

When hook sched related functions, sometimes it is necessary to
specify a task instead of the current task.

Signed-off-by: Feng Zhou <[email protected]>
---
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 */

/**
@@ -2400,6 +2419,7 @@ BTF_ID_FLAGS(func, bpf_cgroup_acquire, KF_ACQUIRE | KF_RCU | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_cgroup_release, KF_RELEASE)
BTF_ID_FLAGS(func, bpf_cgroup_ancestor, KF_ACQUIRE | KF_RCU | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_cgroup_from_id, KF_ACQUIRE | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_task_under_cgroup, KF_RCU)
#endif
BTF_ID_FLAGS(func, bpf_task_from_pid, KF_ACQUIRE | KF_RET_NULL)
BTF_SET8_END(generic_btf_ids)
--
2.20.1

2023-05-04 14:41:34

by Yonghong Song

Subject: Re: [PATCH bpf-next v5 1/2] bpf: Add bpf_task_under_cgroup() kfunc

On 5/3/23 8:15 PM, Feng zhou wrote:
> From: Feng Zhou <[email protected]>
>
> Add a kfunc that's similar to the bpf_current_task_under_cgroup.
> The difference is that it is a designated task.
>
> When hook sched related functions, sometimes it is necessary to
> specify a task instead of the current task.
>
> Signed-off-by: Feng Zhou <[email protected]>

You can carry my Ack from previous revision since there
is no change to the patch.

Acked-by: Yonghong Song <[email protected]>

2023-05-05 03:30:20

by Feng Zhou

Subject: Re: Re: [PATCH bpf-next v5 1/2] bpf: Add bpf_task_under_cgroup() kfunc

在 2023/5/4 22:29, Yonghong Song 写道:
>
>
> On 5/3/23 8:15 PM, Feng zhou wrote:
>> From: Feng Zhou <[email protected]>
>>
>> Add a kfunc that's similar to the bpf_current_task_under_cgroup.
>> The difference is that it is a designated task.
>>
>> When hook sched related functions, sometimes it is necessary to
>> specify a task instead of the current task.
>>
>> Signed-off-by: Feng Zhou <[email protected]>
>
> You can carry my Ack from previous revision since there
> is no change to the patch.
>
> Acked-by: Yonghong Song <[email protected]>

Will do