On 5/5/23 12:24 AM, Feng Zhou wrote:
在 2023/5/5 15:13, Hao Luo 写道:
On Thu, May 4, 2023 at 11:08 PM Feng zhou <zhoufeng.zf@xxxxxxxxxxxxx>
wrote:
From: Feng Zhou <zhoufeng.zf@xxxxxxxxxxxxx>
test_progs:
Tests new kfunc bpf_task_under_cgroup().
The bpf program saves the new task's pid within a given cgroup to
the remote_pid, which is convenient for the user-mode program to
verify the test correctness.
The user-mode program creates its own mount namespace, and mounts the
cgroupsv2 hierarchy in there, call the fork syscall, then check if
remote_pid and local_pid are unequal.
Signed-off-by: Feng Zhou <zhoufeng.zf@xxxxxxxxxxxxx>
Acked-by: Yonghong Song <yhs@xxxxxx>
---
Hi Feng,
I have a comment about the methodology of the test, but the patch
looks ok to me. Why do we have to test via a tracing program? I think
what we need is just a task and a cgroup. Since we have the kfunc
bpf_task_from_pid() and bpf_cgroup_from_id(), we can write a syscall
program which takes a pid and a cgroup id as input and get the task
and cgroup objects directly in the program.
I like testing via a syscall program because it doesn't depend on the
newtask tracepoint and it should be simpler. But I'm ok with the
current version of the patch, just have some thoughts.
Hao
Yes, your method is also very good. The reason why I did this is because
of Song's suggestion before, hope that the parameter of the hook point
will have a task, so I chose this to test.
The motivation of this patch is:
Trace sched related functions, such as enqueue_task_fair, it is
necessary to
specify a task instead of the current task which within a given cgroup.
So I think it is okay to have a test related to sched.
