selftests: mptcp: add a check for 'add_addr_accepted'

The previous patch fixed an issue with the 'add_addr_accepted' counter.
This was not spot by the test suite.

Check this counter and 'add_addr_signal' in MPTCP Join 'delete re-add
signal' test. This should help spotting similar regressions later on.
These counters are crucial for ensuring the MPTCP path manager correctly
handles the subflow creation via 'ADD_ADDR'.

Signed-off-by: Gang Yan <yangang@kylinos.cn>
Reviewed-by: Geliang Tang <geliang@kernel.org>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20251118-net-mptcp-misc-fixes-6-18-rc6-v1-11-806d3781c95f@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Dwyane-Yan

tools/testing/selftests/net/mptcp/mptcp_join.sh

@@ -4055,38 +4055,45 @@ endpoint_tests()
 			$ns1 10.0.2.1 id 1 flags signal
 		chk_subflow_nr "before delete" 2
 		chk_mptcp_info subflows 1 subflows 1
+		chk_mptcp_info add_addr_signal 2 add_addr_accepted 1
 
 		pm_nl_del_endpoint $ns1 1 10.0.2.1
 		pm_nl_del_endpoint $ns1 2 224.0.0.1
 		sleep 0.5
 		chk_subflow_nr "after delete" 1
 		chk_mptcp_info subflows 0 subflows 0
+		chk_mptcp_info add_addr_signal 0 add_addr_accepted 0
 
 		pm_nl_add_endpoint $ns1 10.0.2.1 id 1 flags signal
 		pm_nl_add_endpoint $ns1 10.0.3.1 id 2 flags signal
 		wait_mpj $ns2
 		chk_subflow_nr "after re-add" 3
 		chk_mptcp_info subflows 2 subflows 2
+		chk_mptcp_info add_addr_signal 2 add_addr_accepted 2
 
 		pm_nl_del_endpoint $ns1 42 10.0.1.1
 		sleep 0.5
 		chk_subflow_nr "after delete ID 0" 2
 		chk_mptcp_info subflows 2 subflows 2
+		chk_mptcp_info add_addr_signal 2 add_addr_accepted 2
 
 		pm_nl_add_endpoint $ns1 10.0.1.1 id 99 flags signal
 		wait_mpj $ns2
 		chk_subflow_nr "after re-add ID 0" 3
 		chk_mptcp_info subflows 3 subflows 3
+		chk_mptcp_info add_addr_signal 3 add_addr_accepted 2
 
 		pm_nl_del_endpoint $ns1 99 10.0.1.1
 		sleep 0.5
 		chk_subflow_nr "after re-delete ID 0" 2
 		chk_mptcp_info subflows 2 subflows 2
+		chk_mptcp_info add_addr_signal 2 add_addr_accepted 2
 
 		pm_nl_add_endpoint $ns1 10.0.1.1 id 88 flags signal
 		wait_mpj $ns2
 		chk_subflow_nr "after re-re-add ID 0" 3
 		chk_mptcp_info subflows 3 subflows 3
+		chk_mptcp_info add_addr_signal 3 add_addr_accepted 2
 		mptcp_lib_kill_group_wait $tests_pid
 
 		kill_events_pids