selftests: mptcp: add explicit test case for remove/readd

From: Paolo Abeni <pabeni@redhat.com>

commit b5e2fb832f48bc01d937a053e0550a1465a2f05d upstream.

Delete and re-create a signal endpoint and ensure that the PM
actually deletes and re-create the subflow.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: e06959e9eebd ("selftests: mptcp: join: test for flush/re-add endpoints")
[ No conflicts, but adapt the test to the helpers in this version:
  - run_tests has been modified a few times to reduce the number of
    positional parameters
  - no pm_nl_check_endpoint helper
  - no chk_mptcp_info helper
  - chk_subflow_nr taking an extra parameter
  - kill_tests_wait instead of mptcp_lib_kill_wait ]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

@@ -3239,6 +3239,29 @@ userspace_tests()
 		chk_join_nr 1 1 1
 		chk_rm_nr 1 1
 	fi
+
+	# remove and re-add
+	if reset "delete re-add signal" &&
+	   mptcp_lib_kallsyms_has "subflow_rebuild_header$"; then
+		pm_nl_set_limits $ns1 1 1
+		pm_nl_set_limits $ns2 1 1
+		pm_nl_add_endpoint $ns1 10.0.2.1 id 1 flags signal
+		run_tests $ns1 $ns2 10.0.1.1 4 0 0 speed_20 2>/dev/null &
+		local tests_pid=$!
+
+		wait_mpj $ns2
+		chk_subflow_nr needtitle "before delete" 2
+
+		pm_nl_del_endpoint $ns1 1 10.0.2.1
+		sleep 0.5
+		chk_subflow_nr "" "after delete" 1
+
+		pm_nl_add_endpoint $ns1 10.0.2.1 flags signal
+		wait_mpj $ns2
+		chk_subflow_nr "" "after re-add" 2
+		kill_tests_wait
+	fi
+
 }
 
 endpoint_tests()