Re: [PATCH net-next v2] selftests: openvswitch: retry instead of sleep

[Adrián Moreno]

On Wed, Jul 10, 2024 at 11:04:59AM GMT, Adrian Moreno wrote:
> There are a couple of places where the test script "sleep"s to wait for
> some external condition to be met.
>
> This is error prone, specially in slow systems (identified in CI by
> "KSFT_MACHINE_SLOW=yes").
>
> To fix this, add a "ovs_wait" function that tries to execute a command
> a few times until it succeeds. The timeout used is set to 5s for
> "normal" systems and doubled if a slow CI machine is detected.
>
> This should make the following work:
>
> $ vng --build  \
>     --config tools/testing/selftests/net/config \
>     --config kernel/configs/debug.config
>
> $ vng --run . --user root -- "make -C tools/testing/selftests/ \
>     KSFT_MACHINE_SLOW=yes TARGETS=net/openvswitch run_tests"
>
> Signed-off-by: Adrian Moreno <amorenoz@xxxxxxxxxx>
> ---
>  .../selftests/net/openvswitch/openvswitch.sh  | 45 +++++++++++++++----
>  .../selftests/net/openvswitch/ovs-dpctl.py    |  1 +
>  2 files changed, 38 insertions(+), 8 deletions(-)
>
> diff --git a/tools/testing/selftests/net/openvswitch/openvswitch.sh b/tools/testing/selftests/net/openvswitch/openvswitch.sh
> index bc71dbc18b21..cc0bfae2bafa 100755
> --- a/tools/testing/selftests/net/openvswitch/openvswitch.sh
> +++ b/tools/testing/selftests/net/openvswitch/openvswitch.sh
> @@ -11,6 +11,11 @@ ksft_skip=4
>  PAUSE_ON_FAIL=no
>  VERBOSE=0
>  TRACING=0
> +WAIT_TIMEOUT=5
> +
> +if test "X$KSFT_MACHINE_SLOW" == "Xyes"; then
> +	WAIT_TIMEOUT=10
> +fi
>
>  tests="
>  	arp_ping				eth-arp: Basic arp ping between two NS
> @@ -29,6 +34,30 @@ info() {
>  	[ $VERBOSE = 0 ] || echo $*
>  }
>
> +ovs_wait() {
> +	info "waiting $WAIT_TIMEOUT s for: $@"
> +
> +	if "$@" ; then
> +		info "wait succeeded immediately"
> +		return 0
> +	fi
> +
> +	# A quick re-check helps speed up small races in fast systems.
> +	# However, fractional sleeps might not necessarily work.
> +	local start=0
> +	sleep 0.1 || { sleep 1; start=1; }
> +
> +	for (( i=start; i<WAIT_TIMEOUT; i++ )); do
> +		if "$@" ; then
> +			info "wait succeeded after $i seconds"
> +			return 0
> +		fi
> +		sleep 1
> +	done
> +	info "wait failed after $i seconds"
> +	return 1
> +}
> +
>  ovs_base=`pwd`
>  sbxs=
>  sbx_add () {
> @@ -278,20 +307,19 @@ test_psample() {
>
>  	# Record psample data.
>  	ovs_spawn_daemon "test_psample" python3 $ovs_base/ovs-dpctl.py psample-events
> +	ovs_wait grep -q "listening for psample events" ${ovs_dir}/stdout
>
>  	# Send a single ping.
> -	sleep 1
>  	ovs_sbx "test_psample" ip netns exec client ping -I c1 172.31.110.20 -c 1 || return 1
> -	sleep 1
>
>  	# We should have received one userspace action upcall and 2 psample packets.
> -	grep -E "userspace action command" $ovs_dir/s0.out >/dev/null 2>&1 || return 1
> +	ovs_wait grep -q "userspace action command" $ovs_dir/s0.out || return 1
>
>  	# client -> server samples should only contain the first 14 bytes of the packet.
> -	grep -E "rate:4294967295,group:1,cookie:c0ffee data:[0-9a-f]{28}$" \
> -			 $ovs_dir/stdout >/dev/null 2>&1 || return 1
> -	grep -E "rate:4294967295,group:2,cookie:eeff0c" \
> -			 $ovs_dir/stdout >/dev/null 2>&1 || return 1
> +	ovs_wait grep -qE "rate:4294967295,group:1,cookie:c0ffee data:[0-9a-f]{28}$" \
> +		$ovs_dir/stdout || return 1
> +
> +	ovs_wait grep -q "rate:4294967295,group:2,cookie:eeff0c" $ovs_dir/stdout || return 1
>
>  	return 0
>  }
> @@ -711,7 +739,8 @@ test_upcall_interfaces() {
>  	ovs_add_netns_and_veths "test_upcall_interfaces" ui0 upc left0 l0 \
>  	    172.31.110.1/24 -u || return 1
>
> -	sleep 1
> +	ovs_wait grep -q "listening on upcall packet handler" ${ovs_dir}/left0.out
> +
>  	info "sending arping"
>  	ip netns exec upc arping -I l0 172.31.110.20 -c 1 \
>  	    >$ovs_dir/arping.stdout 2>$ovs_dir/arping.stderr
> diff --git a/tools/testing/selftests/net/openvswitch/ovs-dpctl.py b/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
> index 1e15b0818074..8a0396bfaf99 100644
> --- a/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
> +++ b/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
> @@ -2520,6 +2520,7 @@ class PsampleEvent(EventSocket):
>      marshal_class = psample_msg
>
>      def read_samples(self):
> +        print("listening for psample events", flush=True)
>          while True:
>              try:
>                  for msg in self.get():
> --
> 2.45.2
>


This patch is supposed to fix openvswitch selftests on "-dbg" machines.
However, as Simon points out, all recent rounds are failing [1]. I don't
see this patch being included in the batches and I was wondering why.

Also I see a (presumably unrelated) build error netdev/build_32bit.
Is there anything I can do?

[1]
https://netdev.bots.linux.dev/contest.html?executor=vmksft-net-dbg&test=openvswitch-sh

Thanks.
Adrián