Re: [PATCH mptcp-net] selftests: mptcp: join: fix local endp not being tracked

[Mat Martineau <martineau@kernel.org>]

On Mon, 22 Dec 2025, Matthieu Baerts (NGI0) wrote:

> When running this mptcp_join.sh selftest on older kernel versions not
> supporting local endpoints tracking, this test fails because 3 MP_JOIN
> ACKs have been received, while only 2 were expected.
>
> It is not clear why only 2 MP_JOIN ACKs were expected on old kernel
> versions, while 3 MP_JOIN SYN and SYN+ACK were expected. When testing on
> the v5.15.197 kernel, 3 MP_JOIN ACKs are seen, which is also what is
> expected in the selftests included in this kernel version, see commit
> f4480eaad489 ("selftests: mptcp: add missing join check").
>
> Switch the expected MP_JOIN ACKs to 3. While at it, move this
> chk_join_nr helper out of the special condition for older kernel
> versions as it is now the same as with more recent ones. Also, invert
> the condition to be more logical: what's expected on newer kernel
> versions having such helper first.
>
> Fixes: d4c81bbb8600 ("selftests: mptcp: join: support local endpoint being tracked or not")
> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>

Looks good to me, thanks Matthieu.

Reviewed-by: Mat Martineau <martineau@kernel.org>

> ---
> tools/testing/selftests/net/mptcp/mptcp_join.sh | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
> index b2e6e548f796..f1a0d812e642 100755
> --- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
> +++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
> @@ -2329,17 +2329,16 @@ signal_address_tests()
> 		ip netns exec $ns1 sysctl -q net.mptcp.add_addr_timeout=1
> 		speed=slow \
> 			run_tests $ns1 $ns2 10.0.1.1
> +		chk_join_nr 3 3 3
>
> 		# It is not directly linked to the commit introducing this
> 		# symbol but for the parent one which is linked anyway.
> -		if ! mptcp_lib_kallsyms_has "mptcp_pm_subflow_check_next$"; then
> -			chk_join_nr 3 3 2
> -			chk_add_nr 4 4
> -		else
> -			chk_join_nr 3 3 3
> +		if mptcp_lib_kallsyms_has "mptcp_pm_subflow_check_next$"; then
> 			# the server will not signal the address terminating
> 			# the MPC subflow
> 			chk_add_nr 3 3
> +		else
> +			chk_add_nr 4 4
> 		fi
> 	fi
> }
>
> ---
> base-commit: fab1280894b693ae0b9bb08f21f74852f112db79
> change-id: 20251222-sft-5-15-signal-race-test-ec18c70d295a
>
> Best regards,
> -- 
> Matthieu Baerts (NGI0) <matttbe@kernel.org>
>
>
>