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

On Tue, 2023-01-31 at 08:33 -0500, 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.

...

---

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

Agreed. Additionally you could use constant, sub-second delay (say 0.1) to keep the runtime delta relatively low.

Cheers,

Paolo