Subject: [PATCH v2] tools/testing/selftests/bpf/test_tc_tunnel.sh: Prevent client connect before server bind

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) <[email protected]>
---
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 910044f08908..7989ec608454 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
--
2.34.1



2024-03-19 23:20:39

by patchwork-bot+netdevbpf

[permalink] [raw]
Subject: Re: [PATCH v2] tools/testing/selftests/bpf/test_tc_tunnel.sh: Prevent client connect before server bind

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <[email protected]>:

On Thu, 14 Mar 2024 10:59:11 +0000 you wrote:
> 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.
>
> [...]

Here is the summary with links:
- [v2] tools/testing/selftests/bpf/test_tc_tunnel.sh: Prevent client connect before server bind
https://git.kernel.org/bpf/bpf-next/c/f803bcf9208a

You are awesome, thank you!
--
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