selftests: mlxsw: qos_defprio: Use until_counter_is

Instead of hand-coding the busywait() predicate, use the until_counter_is()
introduced recently.
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Reviewed-by: NAmit Cohen <amitc@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tools/testing/selftests/drivers/net/mlxsw/qos_defprio.sh

@@ -114,23 +114,12 @@ ping_ipv4()
 	ping_test $h1 192.0.2.2
 }
 
-wait_for_packets()
-{
-	local t0=$1; shift
-	local prio_observe=$1; shift
-
-	local t1=$(ethtool_stats_get $swp1 rx_frames_prio_$prio_observe)
-	local delta=$((t1 - t0))
-	echo $delta
-	((delta >= 10))
-}
-
 __test_defprio()
 {
 	local prio_install=$1; shift
 	local prio_observe=$1; shift
-	local delta
 	local key
+	local t1
 	local i
 
 	RET=0
@@ -139,9 +128,10 @@ __test_defprio()
 
 	local t0=$(ethtool_stats_get $swp1 rx_frames_prio_$prio_observe)
 	mausezahn -q $h1 -d 100m -c 10 -t arp reply
-	delta=$(busywait "$HIT_TIMEOUT" wait_for_packets $t0 $prio_observe)
+	t1=$(busywait "$HIT_TIMEOUT" until_counter_is ">= $((t0 + 10))" \
+		ethtool_stats_get $swp1 rx_frames_prio_$prio_observe)
 
-	check_err $? "Default priority $prio_install/$prio_observe: Expected to capture 10 packets, got $delta."
+	check_err $? "Default priority $prio_install/$prio_observe: Expected to capture 10 packets, got $((t1 - t0))."
 	log_test "Default priority $prio_install/$prio_observe"
 
 	defprio_uninstall $swp1 $prio_install