selftests: mptcp: more robust signal race test

The in kernel MPTCP PM implementation can process a single
incoming add address option at any given time. In the
mentioned test the server can surpass such limit. Let the
setup cope with that allowing a faster add_addr retransmission.

Fixes: a88c9e4 ("mptcp: do not block subflows creation on errors")
Fixes: f7efc77 ("mptcp: drop argument port from mptcp_pm_announce_addr")
Closes: multipath-tcp/mptcp_net-next#254
Reported-and-tested-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -752,11 +752,17 @@ chk_add_nr()
 	local mis_ack_nr=${8:-0}
 	local count
 	local dump_stats
+	local timeout
+
+	timeout=`ip netns exec $ns1 sysctl -n net.mptcp.add_addr_timeout`
 
 	printf "%-39s %s" " " "add"
-	count=`ip netns exec $ns2 nstat -as | grep MPTcpExtAddAddr | awk '{print $2}'`
+	count=`ip netns exec $ns2 nstat -as MPTcpExtAddAddr | grep MPTcpExtAddAddr | awk '{print $2}'`
 	[ -z "$count" ] && count=0
-	if [ "$count" != "$add_nr" ]; then
+
+	# if the test configured a short timeout tolerate greater then expected
+	# add addrs options, due to retransmissions
+	if [ "$count" != "$add_nr" ] && [ "$timeout" -gt 1 -o "$count" -lt "$add_nr" ]; then
 		echo "[fail] got $count ADD_ADDR[s] expected $add_nr"
 		ret=1
 		dump_stats=1
@@ -1158,7 +1164,10 @@ signal_address_tests()
 	ip netns exec $ns2 ./pm_nl_ctl add 10.0.2.2 flags signal
 	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags signal
 	ip netns exec $ns2 ./pm_nl_ctl add 10.0.4.2 flags signal
-	run_tests $ns1 $ns2 10.0.1.1
+
+	# the peer could possibly miss some addr notification, allow retransmission
+	ip netns exec $ns1 sysctl -q net.mptcp.add_addr_timeout=1
+	run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
 	chk_join_nr "signal addresses race test" 3 3 3
 
 	# the server will not signal the address terminating