[PATCH v2] selftests/net: synchronize udpgso_bench rx and tx

[Lucas Karpinski]

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@xxxxxxxxxx>
Signed-off-by: Lucas Karpinski <lkarpins@xxxxxxxxxx>
---
https://lore.kernel.org/all/t7v6mmuobrbucyfpwqbcujtvpa3wxnsrc36cz5rr6kzzrzkwtj@toz6mr4ggnyp/

Changelog v2: 
- applied synchronization method suggested by Pablo
- changed commit message to code 

 tools/testing/selftests/net/udpgro.sh         | 27 ++++++++++++++-----
 tools/testing/selftests/net/udpgro_bench.sh   | 19 +++++++++++--
 tools/testing/selftests/net/udpgro_frglist.sh | 19 +++++++++++--
 3 files changed, 54 insertions(+), 11 deletions(-)

diff --git a/tools/testing/selftests/net/udpgro.sh b/tools/testing/selftests/net/udpgro.sh
index 0c743752669a..04792a315729 100755
--- a/tools/testing/selftests/net/udpgro.sh
+++ b/tools/testing/selftests/net/udpgro.sh
@@ -24,6 +24,22 @@ cleanup() {
 }
 trap cleanup EXIT
 
+wait_local_port_listen()
+{
+	local port="${1}"
+
+	local port_hex
+	port_hex="$(printf "%04X" "${port}")"
+
+	local i
+	for i in $(seq 10); do
+		ip netns exec "${PEER_NS}" cat /proc/net/udp* | \
+			awk "BEGIN {rc=1} {if (\$2 ~ /:${port_hex}\$/) {rc=0; exit}} END {exit rc}" &&
+			break
+		sleep 0.1
+	done
+}
+
 cfg_veth() {
 	ip netns add "${PEER_NS}"
 	ip -netns "${PEER_NS}" link set lo up
@@ -51,8 +67,7 @@ run_one() {
 		echo "ok" || \
 		echo "failed" &
 
-	# Hack: let bg programs complete the startup
-	sleep 0.2
+	wait_local_port_listen 8000
 	./udpgso_bench_tx ${tx_args}
 	ret=$?
 	wait $(jobs -p)
@@ -97,7 +112,7 @@ run_one_nat() {
 		echo "ok" || \
 		echo "failed"&
 
-	sleep 0.1
+	wait_local_port_listen 8000
 	./udpgso_bench_tx ${tx_args}
 	ret=$?
 	kill -INT $pid
@@ -118,11 +133,9 @@ run_one_2sock() {
 		echo "ok" || \
 		echo "failed" &
 
-	# Hack: let bg programs complete the startup
-	sleep 0.2
+	wait_local_port_listen 12345
 	./udpgso_bench_tx ${tx_args} -p 12345
-	sleep 0.1
-	# first UDP GSO socket should be closed at this point
+	wait_local_port_listen 8000
 	./udpgso_bench_tx ${tx_args}
 	ret=$?
 	wait $(jobs -p)
diff --git a/tools/testing/selftests/net/udpgro_bench.sh b/tools/testing/selftests/net/udpgro_bench.sh
index 894972877e8b..91833518e80b 100755
--- a/tools/testing/selftests/net/udpgro_bench.sh
+++ b/tools/testing/selftests/net/udpgro_bench.sh
@@ -16,6 +16,22 @@ cleanup() {
 }
 trap cleanup EXIT
 
+wait_local_port_listen()
+{
+	local port="${1}"
+
+	local port_hex
+	port_hex="$(printf "%04X" "${port}")"
+
+	local i
+	for i in $(seq 10); do
+		ip netns exec "${PEER_NS}" cat /proc/net/udp* | \
+			awk "BEGIN {rc=1} {if (\$2 ~ /:${port_hex}\$/) {rc=0; exit}} END {exit rc}" &&
+			break
+		sleep 0.1
+	done
+}
+
 run_one() {
 	# use 'rx' as separator between sender args and receiver args
 	local -r all="$@"
@@ -40,8 +56,7 @@ 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 8000
 	./udpgso_bench_tx ${tx_args}
 }
 
diff --git a/tools/testing/selftests/net/udpgro_frglist.sh b/tools/testing/selftests/net/udpgro_frglist.sh
index 0a6359bed0b9..0aa2068f122c 100755
--- a/tools/testing/selftests/net/udpgro_frglist.sh
+++ b/tools/testing/selftests/net/udpgro_frglist.sh
@@ -16,6 +16,22 @@ cleanup() {
 }
 trap cleanup EXIT
 
+wait_local_port_listen()
+{
+	local port="${1}"
+
+	local port_hex
+	port_hex="$(printf "%04X" "${port}")"
+
+	local i
+	for i in $(seq 10); do
+		ip netns exec "${PEER_NS}" cat /proc/net/udp* | \
+			awk "BEGIN {rc=1} {if (\$2 ~ /:${port_hex}\$/) {rc=0; exit}} END {exit rc}" &&
+			break
+		sleep 0.1
+	done
+}
+
 run_one() {
 	# use 'rx' as separator between sender args and receiver args
 	local -r all="$@"
@@ -45,8 +61,7 @@ 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 8000
 	./udpgso_bench_tx ${tx_args}
 }
 
-- 
2.41.0