[PATCH AUTOSEL 6.9 02/35] selftests/bpf: Prevent client connect before server bind in test_tc_tunnel.sh

Sasha Levin
2024-05-27T14:12:18Z

From: "Alessandro Carminati (Red Hat)" <alessandro.carminati@gmail.com>

[ Upstream commit f803bcf9208a2540acb4c32bdc3616673169f490 ]

In some systems, the netcat server can incur in delay to start listening.
When this happens, the test can randomly fail in various points.
This is an example error message:

# ip gre none gso
# encap 192.168.1.1 to 192.168.1.2, type gre, mac none len 2000
# test basic connectivity
# Ncat: Connection refused.

The issue stems from a race condition between the netcat client and server.
The test author had addressed this problem by implementing a sleep, which
I have removed in this patch.
This patch introduces a function capable of sleeping for up to two seconds.
However, it can terminate the waiting period early if the port is reported
to be listening.

Signed-off-by: Alessandro Carminati (Red Hat) <alessandro.carminati@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240314105911.213411-1-alessandro.carminati@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/testing/selftests/bpf/test_tc_tunnel.sh | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/test_tc_tunnel.sh b/tools/testing/selftests/bpf/test_tc_tunnel.sh
index 910044f08908a..7989ec6084545 100755
--- a/tools/testing/selftests/bpf/test_tc_tunnel.sh
+++ b/tools/testing/selftests/bpf/test_tc_tunnel.sh
@@ -72,7 +72,6 @@ cleanup() {
server_listen() {
ip netns exec "${ns2}" nc "${netcat_opt}" -l "${port}" > "${outfile}" &
server_pid=$!
- sleep 0.2
}

client_connect() {
@@ -93,6 +92,16 @@ verify_data() {
fi
}

+wait_for_port() {
+ for i in $(seq 20); do
+ if ip netns exec "${ns2}" ss ${2:--4}OHntl | grep -q "$1"; then
+ return 0
+ fi
+ sleep 0.1
+ done
+ return 1
+}
+
set -e

# no arguments: automated test, run all
@@ -193,6 +202,7 @@ setup
# basic communication works
echo "test basic connectivity"
server_listen
+wait_for_port ${port} ${netcat_opt}
client_connect
verify_data

@@ -204,6 +214,7 @@ ip netns exec "${ns1}" tc filter add dev veth1 egress \
section "encap_${tuntype}_${mac}"
echo "test bpf encap without decap (expect failure)"
server_listen
+wait_for_port ${port} ${netcat_opt}
! client_connect

if [[ "$tuntype" =~ "udp" ]]; then
--
2.43.0