Re: [PATCH mptcp-next v3] selftests: mptcp: print stats before socket closure

[Matthieu Baerts <matttbe@kernel.org>]

Hi Geliang,

On 05/09/2026 10:26, Geliang Tang wrote:
> Hi Matt,
> 
> On Sat, 2026-08-15 at 00:28 +0200, Matthieu Baerts (NGI0) wrote:
>> In case of poll timeout, it might be too late to print the stats
>> after
>> the socket closure.
>>
>> Now, in case of poll timeout, 'ss' and 'nstat' are invoked from
>> mptcp_connect to print the stats before exiting. This should help
>> debugging poll timeout issues.
>>
>> Note: for this "workaround", system() is used for debugging purposes
> 
> This print_err_stats() implementation is basically the same as
> mptcp_lib_pr_err_stats() in the shell, right?

Correct.

> I think it's better to use mptcp_lib_pr_err_stats() in the shell to
> print the information. In mptcp_connect.c, when a poll timeout occurs,
> we send a signal to the shell and don't close the socket immediately -
> we wait for the shell to finish printing the information before closing
> it. What do you think of this approach? There's a reference
> implementation in the attachment, but I haven't tested it.
Thank you for your review. I agree that what you suggested is better for
a tool that would be used in production. But here with the selftests, I
don't think we need your long patch with a higher complexity, just for
the selftests. I think it is fine to have some "system()" calls with the
same ss/nstat commands compared to a patch of 50+ lines to get the same
result. No?

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