[PATCH 6.1.y] selftests: mptcp: join: validate fullmesh endp on 1st sf

["Matthieu Baerts (NGI0)" <matttbe@kernel.org>]

commit 4878f9f8421f4587bee7b232c1c8a9d3a7d4d782 upstream.

This case was not covered, and the wrong ID was set before the previous
commit.

The rest is not modified, it is just that it will increase the code
coverage.

The right address ID can be verified by looking at the packet traces. We
could automate that using Netfilter with some cBPF code for example, but
that's always a bit cryptic. Packetdrill seems better fitted for that.

Fixes: 4f49d63352da ("selftests: mptcp: add fullmesh testcases")
Cc: stable@vger.kernel.org
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20240819-net-mptcp-pm-reusing-id-v1-13-38035d40de5b@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ Conflicts in mptcp_join.sh, because the 'run_tests' helper has been
  modified in multiple commits that are not in this version, e.g. commit
  e571fb09c893 ("selftests: mptcp: add speed env var"). The conflict was
  in the context, the new line can still be added at the same place. ]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 tools/testing/selftests/net/mptcp/mptcp_join.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index a73358d753aa..3d6d92d448c6 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -3023,6 +3023,7 @@ fullmesh_tests()
 		pm_nl_set_limits $ns1 1 3
 		pm_nl_set_limits $ns2 1 3
 		pm_nl_add_endpoint $ns1 10.0.2.1 flags signal
+		pm_nl_add_endpoint $ns2 10.0.1.2 flags subflow,fullmesh
 		run_tests $ns1 $ns2 10.0.1.1 0 0 fullmesh_1 slow
 		chk_join_nr 3 3 3
 		chk_add_nr 1 1
-- 
2.45.2