linux-kernel - Re: [PATCH net 2/2] selftests: mptcp: explicitly trigger the listener diag code-path

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Date: Thu, 22 Feb 2024 15:49:44 +0100
From: Matthieu Baerts <matttbe@...nel.org>
To: Simon Horman <horms@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, Mat Martineau <martineau@...nel.org>,
 Geliang Tang <geliang@...nel.org>, "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Shuah Khan <shuah@...nel.org>, mptcp@...ts.linux.dev,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH net 2/2] selftests: mptcp: explicitly trigger the listener
 diag code-path

Hi Simon,

Thank you for the review!

On 22/02/2024 2:13 pm, Simon Horman wrote:
> On Wed, Feb 22, 2024 at 12:46:59PM +0100, Paolo Abeni wrote:
>> l The mptcp diag interface already experienced a few locking bugs
>> that lockdep and appropriate coverage have detected in advance.
>>
>> Let's add a test-case triggering the relevant code path, to prevent
>> similar issues in the future.
>>
>> Signed-off-by: Paolo Abeni <pabeni@...hat.com>
>> ---
>>  tools/testing/selftests/net/mptcp/diag.sh | 30 +++++++++++++++++++++++
>>  1 file changed, 30 insertions(+)
>>
>> diff --git a/tools/testing/selftests/net/mptcp/diag.sh b/tools/testing/selftests/net/mptcp/diag.sh
>> index 60a7009ce1b5..3ab584b38566 100755
>> --- a/tools/testing/selftests/net/mptcp/diag.sh
>> +++ b/tools/testing/selftests/net/mptcp/diag.sh
>> @@ -81,6 +81,21 @@ chk_msk_nr()
>>  	__chk_msk_nr "grep -c token:" "$@"
>>  }
>>  
>> +chk_listener_nr()
>> +{
>> +	local expected=$1
>> +	local msg="$2"
>> +
>> +	if [ $expected -gt 0 ] && \
>> +	   ! mptcp_lib_kallsyms_has "mptcp_diag_dump_listeners"; then
>> +		printf "%-50s%s\n" "$msg - mptcp" "[ skip ]"
>> +		mptcp_lib_result_skip "many listener sockets"
>> +	else
>> +		__chk_nr "ss -inmlHMON $ns | wc -l" "$expected" "$msg - mptcp"
>> +	fi
>> +	__chk_nr "ss -inmlHtON $ns | wc -l" "$expected" "$msg - subflows"
>> +}
>> +
>>  wait_msk_nr()
>>  {
>>  	local condition="grep -c token:"
>> @@ -279,5 +294,20 @@ flush_pids
>>  chk_msk_inuse 0 "many->0"
>>  chk_msk_cestab 0 "many->0"
>>  
>> +chk_listener_nr 0 "no listener sockets"
>> +NR_SERVERS=100
>> +for I in $(seq 1 $NR_SERVERS); do
>> +	ip netns exec $ns ./mptcp_connect -p $((I + 20001)) -l 0.0.0.0 2>&1 >/dev/null &
>> +	mptcp_lib_wait_local_port_listen $ns $((I + 20001))
>> +done
>> +
>> +chk_listener_nr $NR_SERVERS "many listener sockets"
>> +
>> +# gracefull termination
> 
> nit, as you plan to re-spin anyway: graceful

Paolo sent a new version on MPTCP ML only. When applying the new
version, I fixed this:

https://lore.kernel.org/mptcp/e98b8b07-558c-498a-97fb-dd5cab11e439@kernel.org/

>> +for I in $(seq 1 $NR_SERVERS); do
>> +	echo a | ip netns exec $ns ./mptcp_connect -p $((I + 20001)) 127.0.0.1 2>&1 >/dev/null
> 
> I'm not sure of the validity of this but shellcheck complains that:
> 
>   SC2069 (warning): To redirect stdout+stderr, 2>&1 must be last (or use '{ cmd > file; } 2>&1' to clarify).
> 
> Also for the same constriction slightly earlier in this patch.

Good catch!

I should add shellcheck support in our CI to catch that :)

I just applied the suggested modification in our tree [1]. The new
version that will be sent to netdev will no longer have this issue.

https://github.com/multipath-tcp/mptcp_net-next/commit/31f1460d552c

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