testing: selftests: drivers: net: netdevsim: devlink: add test case for hard drop statistics

Add hard drop counter check testcase, to make sure netdevsim driver
properly handles the devlink hard drop counters get/set callbacks.
Signed-off-by: Oleksandr Mazur <oleksandr.mazur@plvision.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/drivers/net/netdevsim/devlink_trap.sh

@@ -165,6 +165,16 @@ trap_stats_test()
 			devlink_trap_action_set $trap_name "drop"
 			devlink_trap_stats_idle_test $trap_name
 			check_err $? "Stats of trap $trap_name not idle when action is drop"
+
+			echo "y"> $DEBUGFS_DIR/fail_trap_drop_counter_get
+			devlink -s trap show $DEVLINK_DEV trap $trap_name &> /dev/null
+			check_fail $? "Managed to read trap (hard dropped) statistics when should not"
+			echo "n"> $DEBUGFS_DIR/fail_trap_drop_counter_get
+			devlink -s trap show $DEVLINK_DEV trap $trap_name &> /dev/null
+			check_err $? "Did not manage to read trap (hard dropped) statistics when should"
+
+			devlink_trap_drop_stats_idle_test $trap_name
+			check_fail $? "Drop stats of trap $trap_name idle when should not"
 		else
 			devlink_trap_stats_idle_test $trap_name
 			check_fail $? "Stats of non-drop trap $trap_name idle when should not"