Re: [ovs-dev] [PATCH v1] selftests: openvswitch: retry instead of sleep

[Ilya Maximets]

On 7/8/24 15:44, 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  | 49 ++++++++++++++++---
>  .../selftests/net/openvswitch/ovs-dpctl.py    |  1 +
>  2 files changed, 42 insertions(+), 8 deletions(-)
> 

Hi, Adrian.  See a small pile of nitpicks below.

None of them are blocking from my perspective, except for a typo.
Just listed them since there is a typo anyway.

> diff --git a/tools/testing/selftests/net/openvswitch/openvswitch.sh b/tools/testing/selftests/net/openvswitch/openvswitch.sh
> index bc71dbc18b21..83407b42073a 100755
> --- a/tools/testing/selftests/net/openvswitch/openvswitch.sh
> +++ b/tools/testing/selftests/net/openvswitch/openvswitch.sh
> @@ -11,6 +11,7 @@ ksft_skip=4
>  PAUSE_ON_FAIL=no
>  VERBOSE=0
>  TRACING=0
> +WAIT_TIMEOUT=5
>  
>  tests="
>  	arp_ping				eth-arp: Basic arp ping between two NS
> @@ -29,6 +30,32 @@ info() {
>  	[ $VERBOSE = 0 ] || echo $*
>  }
>  
> +ovs_wait() {
> +	info "waiting $WAIT_TIMEOUT s for: $@"
> +
> +	"$@"
> +	if [[ $? -eq 0 ]]; then

Maybe just 'if "$@"; then' ?

> +		info "wait succeeded inmediately"

* 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

for i in $(seq ${start} ${WAIT_TIMEOUT}); do

Will need to initialize start to 1 and 2.

It works, but seems like an unnecessary use of non-POSIX constructs.

> +		"$@"
> +		if [[ $? -eq 0 ]]; then

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 +305,21 @@ 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
> +	[[ $? -eq 0 ]] || return 1

Why checking separately and not one the same line with || return 1 ?
Also double brackets seem unnecessary.

>  
>  	# 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
> +	[[ $? -eq 0 ]] || return 1
> +
> +	ovs_wait grep -q "rate:4294967295,group:2,cookie:eeff0c" $ovs_dir/stdout
> +	[[ $? -eq 0 ]] || return 1

Same for above two.

>  
>  	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
> @@ -811,6 +840,10 @@ shift $(($OPTIND-1))
>  IFS="	
>  "
>  
> +if test "X$KSFT_MACHINE_SLOW" == "Xyes"; then
> +	WAIT_TIMEOUT=10
> +fi

Should this be done closer to the first initialization of WAIT_TIMEOUT ?

> +
>  for arg do
>  	# Check first that all requested tests are available before running any
>  	command -v > /dev/null "test_${arg}" || { echo "=== Test ${arg} not found"; usage; }
> 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():