selftests: mptcp: get stats just before timing out

Recently, some debugging happened around a test that was timing out. The
stats were showing connections being closed which was confusing because
the closing state was caused by the timeout stopping the transfer.

To avoid such confusion, the timeout is no longer done per mptcp_connect
process, but separately. In case of timeout, the stats are now printed,
then the apps are killed.

The stats will still be printed after the kill, but that's fine, and
this might even be useful, just in case. Timeout should be exceptional.

Reviewed-by: Geliang Tang <[e-mail]>
Signed-off-by: Matthieu Baerts (NGI0) <[e-mail]>
Link: https://patch.msgid.link/2025111[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

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

···
 		mptcp_lib_nstat_init "${connector_ns}"
 	fi
 
-	timeout ${timeout_test} \
-		ip netns exec ${listener_ns} \
-			./mptcp_connect -t ${timeout_poll} -l -p $port -s ${srv_proto} \
-				$extra_args $local_addr < "$sin" > "$sout" &
+	ip netns exec ${listener_ns} \
+		./mptcp_connect -t ${timeout_poll} -l -p $port -s ${srv_proto} \
+			$extra_args $local_addr < "$sin" > "$sout" &
 	local spid=$!
 
 	mptcp_lib_wait_local_port_listen "${listener_ns}" "${port}"
 
 	local start
 	start=$(date +%s%3N)
-	timeout ${timeout_test} \
-		ip netns exec ${connector_ns} \
-			./mptcp_connect -t ${timeout_poll} -p $port -s ${cl_proto} \
-				$extra_args $connect_addr < "$cin" > "$cout" &
+	ip netns exec ${connector_ns} \
+		./mptcp_connect -t ${timeout_poll} -p $port -s ${cl_proto} \
+			$extra_args $connect_addr < "$cin" > "$cout" &
 	local cpid=$!
+
+	mptcp_lib_wait_timeout "${timeout_test}" "${listener_ns}" \
+		"${connector_ns}" "${port}" "${cpid}" "${spid}" &
+	local timeout_pid=$!
 
 	wait $cpid
 	local retc=$?
 	wait $spid
 	local rets=$?
+
+	if kill -0 $timeout_pid; then
+		# Finished before the timeout: kill the background job
+		mptcp_lib_kill_group_wait $timeout_pid
+		timeout_pid=0
+	fi
 
 	local stop
 	stop=$(date +%s%3N)
···
 	local duration
 	duration=$((stop-start))
 	printf "(duration %05sms) " "${duration}"
-	if [ ${rets} -ne 0 ] || [ ${retc} -ne 0 ]; then
+	if [ ${rets} -ne 0 ] || [ ${retc} -ne 0 ] || [ ${timeout_pid} -ne 0 ]; then
 		mptcp_lib_pr_fail "client exit code $retc, server $rets"
 		mptcp_lib_pr_err_stats "${listener_ns}" "${connector_ns}" "${port}"
 

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

···
 	if [ "$test_linkfail" -gt 1 ];then
 		listener_in="${sinfail}"
 	fi
-	timeout ${timeout_test} \
-		ip netns exec ${listener_ns} \
-			./mptcp_connect -t ${timeout_poll} -l -p ${port} -s ${srv_proto} \
-				${extra_srv_args} "${bind_addr}" < "${listener_in}" > "${sout}" &
+	ip netns exec ${listener_ns} \
+		./mptcp_connect -t ${timeout_poll} -l -p ${port} -s ${srv_proto} \
+			${extra_srv_args} "${bind_addr}" < "${listener_in}" > "${sout}" &
 	local spid=$!
 
 	mptcp_lib_wait_local_port_listen "${listener_ns}" "${port}"
 
 	extra_cl_args="$extra_args $extra_cl_args"
 	if [ "$test_linkfail" -eq 0 ];then
-		timeout ${timeout_test} \
-			ip netns exec ${connector_ns} \
-				./mptcp_connect -t ${timeout_poll} -p $port -s ${cl_proto} \
-					$extra_cl_args $connect_addr < "$cin" > "$cout" &
+		ip netns exec ${connector_ns} \
+			./mptcp_connect -t ${timeout_poll} -p $port -s ${cl_proto} \
+				$extra_cl_args $connect_addr < "$cin" > "$cout" &
 	elif [ "$test_linkfail" -eq 1 ] || [ "$test_linkfail" -eq 2 ];then
 		connector_in="${cinsent}"
 		( cat "$cinfail" ; sleep 2; link_failure $listener_ns ; cat "$cinfail" ) | \
 			tee "$cinsent" | \
-			timeout ${timeout_test} \
 				ip netns exec ${connector_ns} \
 					./mptcp_connect -t ${timeout_poll} -p $port -s ${cl_proto} \
 						$extra_cl_args $connect_addr > "$cout" &
 	else
 		connector_in="${cinsent}"
 		tee "$cinsent" < "$cinfail" | \
-			timeout ${timeout_test} \
-				ip netns exec ${connector_ns} \
-					./mptcp_connect -t ${timeout_poll} -p $port -s ${cl_proto} \
-						$extra_cl_args $connect_addr > "$cout" &
+			ip netns exec ${connector_ns} \
+				./mptcp_connect -t ${timeout_poll} -p $port -s ${cl_proto} \
+					$extra_cl_args $connect_addr > "$cout" &
 	fi
 	local cpid=$!
+
+	mptcp_lib_wait_timeout "${timeout_test}" "${listener_ns}" \
+		"${connector_ns}" "${port}" "${cpid}" "${spid}" &
+	local timeout_pid=$!
 
 	pm_nl_set_endpoint $listener_ns $connector_ns $connect_addr
 	check_cestab $listener_ns $connector_ns
···
 	wait $spid
 	local rets=$?
 
+	if kill -0 $timeout_pid; then
+		# Finished before the timeout: kill the background job
+		mptcp_lib_kill_group_wait $timeout_pid
+		timeout_pid=0
+	fi
+
 	cond_stop_capture
 
 	mptcp_lib_nstat_get "${listener_ns}"
 	mptcp_lib_nstat_get "${connector_ns}"
 
-	if [ ${rets} -ne 0 ] || [ ${retc} -ne 0 ]; then
+	if [ ${rets} -ne 0 ] || [ ${retc} -ne 0 ] || [ ${timeout_pid} -ne 0 ]; then
 		fail_test "client exit code $retc, server $rets"
 		mptcp_lib_pr_err_stats "${listener_ns}" "${connector_ns}" "${port}"
 		return 1

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

···
 		mptcp_lib_get_info_value "${1}" "^type:${3:-1},"
 }
 
+mptcp_lib_wait_timeout() {
+	local timeout_test="${1}"
+	local listener_ns="${2}"
+	local connector_ns="${3}"
+	local port="${4}"
+	shift 4 # rest are PIDs
+
+	sleep "${timeout_test}"
+	mptcp_lib_print_err "timeout"
+	mptcp_lib_pr_err_stats "${listener_ns}" "${connector_ns}" "${port}"
+	kill "${@}" 2>/dev/null
+}
+
 # $1: PID
 mptcp_lib_kill_wait() {
 	[ "${1}" -eq 0 ] && return 0

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

···
 	mptcp_lib_nstat_init "${listener_ns}"
 	mptcp_lib_nstat_init "${connector_ns}"
 
-	timeout ${timeout_test} \
-		ip netns exec ${listener_ns} \
-			$mptcp_connect -t ${timeout_poll} -l -M 1 -p $port -s ${srv_proto} -c "${cmsg}" \
-				${local_addr} < "$sin" > "$sout" &
+	ip netns exec ${listener_ns} \
+		$mptcp_connect -t ${timeout_poll} -l -M 1 -p $port -s ${srv_proto} -c "${cmsg}" \
+			${local_addr} < "$sin" > "$sout" &
 	local spid=$!
 
 	mptcp_lib_wait_local_port_listen "${listener_ns}" "${port}"
 
-	timeout ${timeout_test} \
-		ip netns exec ${connector_ns} \
-			$mptcp_connect -t ${timeout_poll} -M 2 -p $port -s ${cl_proto} -c "${cmsg}" \
-				$connect_addr < "$cin" > "$cout" &
+	ip netns exec ${connector_ns} \
+		$mptcp_connect -t ${timeout_poll} -M 2 -p $port -s ${cl_proto} -c "${cmsg}" \
+			$connect_addr < "$cin" > "$cout" &
 
 	local cpid=$!
+
+	mptcp_lib_wait_timeout "${timeout_test}" "${listener_ns}" \
+		"${connector_ns}" "${port}" "${cpid}" "${spid}" &
+	local timeout_pid=$!
 
 	wait $cpid
 	local retc=$?
 	wait $spid
 	local rets=$?
 
+	if kill -0 $timeout_pid; then
+		# Finished before the timeout: kill the background job
+		mptcp_lib_kill_group_wait $timeout_pid
+		timeout_pid=0
+	fi
+
 	mptcp_lib_nstat_get "${listener_ns}"
 	mptcp_lib_nstat_get "${connector_ns}"
 
 	print_title "Transfer ${ip:2}"
-	if [ ${rets} -ne 0 ] || [ ${retc} -ne 0 ]; then
+	if [ ${rets} -ne 0 ] || [ ${retc} -ne 0 ] || [ ${timeout_pid} -ne 0 ]; then
 		mptcp_lib_pr_fail "client exit code $retc, server $rets"
 		mptcp_lib_pr_err_stats "${listener_ns}" "${connector_ns}" "${port}"
 

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

···
 	mptcp_lib_nstat_init "${ns3}"
 	mptcp_lib_nstat_init "${ns1}"
 
-	timeout ${timeout_test} \
-		ip netns exec ${ns3} \
-			./mptcp_connect -jt ${timeout_poll} -l -p $port -T $max_time \
-				0.0.0.0 < "$sin" > "$sout" &
+	ip netns exec ${ns3} \
+		./mptcp_connect -jt ${timeout_poll} -l -p $port -T $max_time \
+			0.0.0.0 < "$sin" > "$sout" &
 	local spid=$!
 
 	mptcp_lib_wait_local_port_listen "${ns3}" "${port}"
 
-	timeout ${timeout_test} \
-		ip netns exec ${ns1} \
-			./mptcp_connect -jt ${timeout_poll} -p $port -T $max_time \
-				10.0.3.3 < "$cin" > "$cout" &
+	ip netns exec ${ns1} \
+		./mptcp_connect -jt ${timeout_poll} -p $port -T $max_time \
+			10.0.3.3 < "$cin" > "$cout" &
 	local cpid=$!
+
+	mptcp_lib_wait_timeout "${timeout_test}" "${ns3}" "${ns1}" "${port}" \
+		"${cpid}" "${spid}" &
+	local timeout_pid=$!
 
 	wait $cpid
 	local retc=$?
 	wait $spid
 	local rets=$?
+
+	if kill -0 $timeout_pid; then
+		# Finished before the timeout: kill the background job
+		mptcp_lib_kill_group_wait $timeout_pid
+		timeout_pid=0
+	fi
 
 	if $capture; then
 		sleep 1
···
 	cmp $cin $sout > /dev/null 2>&1
 	local cmpc=$?
 
-	if [ $retc -eq 0 ] && [ $rets -eq 0 ] && \
-	   [ $cmpc -eq 0 ] && [ $cmps -eq 0 ]; then
+	if [ $retc -eq 0 ] && [ $rets -eq 0 ] &&
+	   [ $cmpc -eq 0 ] && [ $cmps -eq 0 ] &&
+	   [ $timeout_pid -eq 0 ]; then
 		printf "%-16s" " max $max_time "
 		mptcp_lib_pr_ok
 		cat "$capout"