selftests: devlink_lib: Split out helper

Merely checking whether a trap counter incremented or not without
logging a test result is useful on its own. Split this functionality to
a helper which will be used by subsequent patches.
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/forwarding/devlink_lib.sh

@@ -503,25 +503,30 @@ devlink_trap_drop_cleanup()
 	tc filter del dev $dev egress protocol $proto pref $pref handle $handle flower
 }
 
-devlink_trap_stats_test()
+devlink_trap_stats_check()
 {
-	local test_name=$1; shift
 	local trap_name=$1; shift
 	local send_one="$@"
 	local t0_packets
 	local t1_packets
 
-	RET=0
-
 	t0_packets=$(devlink_trap_rx_packets_get $trap_name)
 
 	$send_one && sleep 1
 
 	t1_packets=$(devlink_trap_rx_packets_get $trap_name)
 
-	if [[ $t1_packets -eq $t0_packets ]]; then
-		check_err 1 "Trap stats did not increase"
-	fi
+	[[ $t1_packets -ne $t0_packets ]]
+}
+
+devlink_trap_stats_test()
+{
+	local test_name=$1; shift
+
+	RET=0
+
+	devlink_trap_stats_check "$@"
+	check_err $? "Trap stats did not increase"
 
 	log_test "$test_name"
 }