selftests: mptcp: join: fix local endp not being tracked

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")
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/20260127-net-mptcp-dup-nl-events-v1-5-7f71e1bc4feb@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index 3fc29201362af534e32d58ef140653448083180d..e70d3420954fc13741896a6880fa75dd0e4e0ebb 100755 (executable)
--- 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
 }