Re: [PATCH v3 mptcp-next 3/3] selftests: mptcp: update and extend fastclose test-cases

[Matthieu Baerts <matthieu.baerts@tessares.net>]

Hi Paolo,

On 09/09/2022 10:09, Paolo Abeni wrote:
> On Wed, 2022-09-07 at 19:22 +0200, Matthieu Baerts wrote:
>> On 01/09/2022 19:31, Paolo Abeni wrote:
>>> After the previous patches, the MPTCP protocol can generate
>>> fast-closes on both ends of the connection. Rework the relevant
>>> test-case to carefully trigger the fast-close code-path on a
>>> single end at the time, while ensuring than a predictable amount
>>> of data is spooled on both ends.
>>>
>>> Additionally add another test-cases for the passive socket
>>> fast-close.
>>
>> Thank you for the v3!
>>
>> (...)
>>
>>> diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.c b/tools/testing/selftests/net/mptcp/mptcp_connect.c
>>> index 24d4e9cb617e..ee6df83c55f3 100644
>>> --- a/tools/testing/selftests/net/mptcp/mptcp_connect.c
>>> +++ b/tools/testing/selftests/net/mptcp/mptcp_connect.c

(...)

>>> @@ -1236,7 +1283,7 @@ chk_rst_nr()
>>>  	printf "%-${nr_blank}s %s" " " "rtx"
>>>  	count=$(ip netns exec $ns_tx nstat -as | grep MPTcpExtMPRstTx | awk '{print $2}')
>>>  	[ -z "$count" ] && count=0
>>> -	if [ "$count" != "$rst_tx" ]; then
>>> +	if [ $count -lt $rst_tx ]; then
>>
>> Why is it fine if we send (and below receive) more than expected?
> 
> [answering only here because this will be the only suggestion leading
> to no changes in the next revision]
> 
> Because the rst can be retransmitted. I'm not sure/can't recall how the
> self-test previously was able to enforce a single reset, but that does
> not look possible now.

Indeed, good idea to do that! I guess we can control the number of
retransmissions in general but not specific to the reset: we don't want
to not accept any retransmissions of the previous data packets.

(I'm sorry to repeat the same kind of thing again but should we extract
this part and have a dedicated commit for -net? :) )

Cheers,
Matt
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