Re: [PATCH v2 3/4] selftests: net: udpgso_bench: Fix racing bug between the rx/tx programs

Willem de Bruijn
2023-01-31T13:34:19Z

On Tue, Jan 31, 2023 at 8:06 AM Andrei Gherzan
<andrei.gherzan@canonical.com> wrote:
>
> "udpgro_bench.sh" invokes udpgso_bench_rx/udpgso_bench_tx programs
> subsequently and while doing so, there is a chance that the rx one is not
> ready to accept socket connections. This racing bug could fail the test
> with at least one of the following:
>
> ./udpgso_bench_tx: connect: Connection refused
> ./udpgso_bench_tx: sendmsg: Connection refused
> ./udpgso_bench_tx: write: Connection refused
>
> This change addresses this by making udpgro_bench.sh wait for the rx
> program to be ready before firing off the tx one - with an exponential back
> off algorithm from 1s to 10s.
>
> Signed-off-by: Andrei Gherzan <andrei.gherzan@canonical.com>

please CC: reviewers of previous revisions on new revisions

also for upcoming patches: please clearly mark net or net-next.
> ---
> tools/testing/selftests/net/udpgso_bench.sh | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/tools/testing/selftests/net/udpgso_bench.sh b/tools/testing/selftests/net/udpgso_bench.sh
> index dc932fd65363..20b5db8fcbde 100755
> --- a/tools/testing/selftests/net/udpgso_bench.sh
> +++ b/tools/testing/selftests/net/udpgso_bench.sh
> @@ -7,6 +7,7 @@ readonly GREEN='\033[0;92m'
> readonly YELLOW='\033[0;33m'
> readonly RED='\033[0;31m'
> readonly NC='\033[0m' # No Color
> +readonly TESTPORT=8000 # Keep this in sync with udpgso_bench_rx/tx

then also pass explicit -p argument to the processes to keep all three
consistent

>
> readonly KSFT_PASS=0
> readonly KSFT_FAIL=1
> @@ -56,10 +57,27 @@ trap wake_children EXIT
>
> run_one() {
> local -r args=$@
> + local -r init_delay_s=1
> + local -r max_delay_s=10
> + local delay_s=0
> + local nr_socks=0
>
> ./udpgso_bench_rx &
> ./udpgso_bench_rx -t &
>
> + # Wait for the above test program to get ready to receive connections.
> + delay_s="${init_delay_s}"
> + while [ "$delay_s" -lt "$max_delay_s" ]; do
> + nr_socks="$(ss -lnHi | grep -c "\*:${TESTPORT}")"
> + [ "$nr_socks" -eq 2 ] && break
> + sleep "$delay_s"
> + delay="$((delay*2))"

I don't think we need exponential back-off for something this simple

> + done
> + if [ "$nr_socks" -ne 2 ]; then
> + echo "timed out while waiting for udpgso_bench_rx"
> + exit 1
> + fi
> +
> ./udpgso_bench_tx ${args}
> }
>
> --
> 2.34.1
>