Commit f803bcf9 authored Mar 14, 2024 by Alessandro Carminati (Red Hat) Committed by Andrii Nakryiko Mar 19, 2024

selftests/bpf: Prevent client connect before server bind in test_tc_tunnel.sh



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

parent 437ffcb0

tools/testing/selftests/bpf/test_tc_tunnel.sh

+12 −1

Original line number	Diff line number	Diff line
		@@ -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