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

Andrei Gherzan
2023-01-31T14:56:24Z

On 23/01/31 08:33AM, Willem de Bruijn wrote:
> 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.

Ack. I'll do all that in next v.

> > ---
> > 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

I have no idea how I've missed it. It will be in v4.

>
> >
> > 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

I'm happy to drop/simplify. I'll go for a simple sleep 1 in a timeout
loop.

>
> > + 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
> >

--
Andrei Gherzan