Re: [PATCH mptcp-net v2 2/6] selftests: mptcp: join: rm: set backup flag

[Matthieu Baerts <matttbe@kernel.org>]

On 04/11/2025 09:47, Matthieu Baerts wrote:
> On 04/11/2025 08:29, Geliang Tang wrote:
>> Hi Matt,
>>
>> On Tue, 2025-11-04 at 07:57 +0100, Matthieu Baerts wrote:
>>> Hi Geliang,
>>>
>>> Thank you for the review.
>>>
>>> 4 Nov 2025 07:06:34 Geliang Tang <geliang@kernel.org>:
>>>
>>>> Hi Matt,
>>>>
>>>> Thanks for this fix. It works indeed.
>>>>
>>>> On Sun, 2025-11-02 at 12:30 +0100, Matthieu Baerts (NGI0) wrote:
>>>>> Some of these 'remove' tests rarely fail because a subflow has
>>>>> been
>>>>
>>>> In my testing, only the "flush addresses" test case fails
>>>> intermittently. I'm wondering which other test cases have failed in
>>>> your environment?
>>>
>>> I took the unstable ones from the Netdev and MPTCP CIs:
>>>
>>> https://netdev.bots.linux.dev/contest.html?pass=0&executor=vmksft-mptcp-dbg&ld-cases=1
>>>
>>> https://ci-results.mptcp.dev/flakes.html
>>>
>>>> I'm thinking we shouldn't add the "backup" flag to every test in
>>>> remove_tests, but only to the specific ones that are actually
>>>> failing.
>>>>
>>>> Similarly for patches 3 and 4, we don't need to add
>>>> "test_linkfail=128"
>>>> to every test. We should only apply it to the specific ones that
>>>> are
>>>> actually failing.
>>>
>>> If my analysis is correct, it means the simple fixes I did (backup
>>> and
>>> longer file size) can be applied to multiple tests. Then probably
>>> better
>>> to avoid these other tests to fail for the same reasons even if it is
>>> very
>>> rare, and very hard to reproduce, no? Each false positive takes a lot
>>> of
>>> resources (mainly time) to debug.
>>
>> I'll leave it to you to decide. However, I still believe it's better to
>> apply these fixes to the tests one by one, in case we see failures in
>> the future.
> 
> Because these modifications are not modifying what is being validated in
> the test, but only avoid noises that would make the tests failing, I
> think it is better to prevent issues and waiting for them to happen.

I meant to say: "it is better to prevent issues *than* waiting for them
to happen.".

> 
>> I'll respond with my Reviewed-by tag in the cover letter.
> 
> Thanks!
> 
> Cheers,
> Matt

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.