selftests/net: synchronize udpgro tests' tx and rx connection

The sockets used by udpgso_bench_tx aren't always ready when
udpgso_bench_tx transmits packets. This issue is more prevalent in -rt
kernels, but can occur in both. Replace the hacky sleep calls with a
function that checks whether the ports in the namespace are ready for
use.
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Lucas Karpinski <lkarpins@redhat.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/net_helper.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Helper functions
+
+wait_local_port_listen()
+{
+	local listener_ns="${1}"
+	local port="${2}"
+	local protocol="${3}"
+	local port_hex
+	local i
+
+	port_hex="$(printf "%04X" "${port}")"
+	for i in $(seq 10); do
+		if ip netns exec "${listener_ns}" cat /proc/net/"${protocol}"* | \
+		   grep -q "${port_hex}"; then
+			break
+		fi
+		sleep 0.1
+	done
+}

tools/testing/selftests/net/udpgro.sh

@@ -3,6 +3,8 @@
 #
 # Run a series of udpgro functional tests.
 
+source net_helper.sh
+
 readonly PEER_NS="ns-peer-$(mktemp -u XXXXXX)"
 
 BPF_FILE="../bpf/xdp_dummy.bpf.o"
@@ -51,8 +53,7 @@ run_one() {
 		echo "ok" || \
 		echo "failed" &
 
-	# Hack: let bg programs complete the startup
-	sleep 0.2
+	wait_local_port_listen ${PEER_NS} 8000 udp
 	./udpgso_bench_tx ${tx_args}
 	ret=$?
 	wait $(jobs -p)
@@ -97,7 +98,7 @@ run_one_nat() {
 		echo "ok" || \
 		echo "failed"&
 
-	sleep 0.1
+	wait_local_port_listen "${PEER_NS}" 8000 udp
 	./udpgso_bench_tx ${tx_args}
 	ret=$?
 	kill -INT $pid
@@ -118,11 +119,9 @@ run_one_2sock() {
 		echo "ok" || \
 		echo "failed" &
 
-	# Hack: let bg programs complete the startup
-	sleep 0.2
+	wait_local_port_listen "${PEER_NS}" 12345 udp
 	./udpgso_bench_tx ${tx_args} -p 12345
-	sleep 0.1
-	# first UDP GSO socket should be closed at this point
+	wait_local_port_listen "${PEER_NS}" 8000 udp
 	./udpgso_bench_tx ${tx_args}
 	ret=$?
 	wait $(jobs -p)

tools/testing/selftests/net/udpgro_bench.sh

@@ -3,6 +3,8 @@
 #
 # Run a series of udpgro benchmarks
 
+source net_helper.sh
+
 readonly PEER_NS="ns-peer-$(mktemp -u XXXXXX)"
 
 BPF_FILE="../bpf/xdp_dummy.bpf.o"
@@ -40,8 +42,7 @@ run_one() {
 	ip netns exec "${PEER_NS}" ./udpgso_bench_rx ${rx_args} -r &
 	ip netns exec "${PEER_NS}" ./udpgso_bench_rx -t ${rx_args} -r &
 
-	# Hack: let bg programs complete the startup
-	sleep 0.2
+	wait_local_port_listen "${PEER_NS}" 8000 udp
 	./udpgso_bench_tx ${tx_args}
 }
 

tools/testing/selftests/net/udpgro_frglist.sh

@@ -3,6 +3,8 @@
 #
 # Run a series of udpgro benchmarks
 
+source net_helper.sh
+
 readonly PEER_NS="ns-peer-$(mktemp -u XXXXXX)"
 
 BPF_FILE="../bpf/xdp_dummy.bpf.o"
@@ -45,8 +47,7 @@ run_one() {
         echo ${rx_args}
 	ip netns exec "${PEER_NS}" ./udpgso_bench_rx ${rx_args} -r &
 
-	# Hack: let bg programs complete the startup
-	sleep 0.2
+	wait_local_port_listen "${PEER_NS}" 8000 udp
 	./udpgso_bench_tx ${tx_args}
 }