Solve warnings.

src/Makefile

@@ -13,3 +13,4 @@ obj-m += ebt_xtip.o
 obj-m += ebt_xtip6.o
 obj-m += ebt_igmpsnooping.o
 obj-m += ebt_mldsnooping.o
+EXTRA_CFLAGS +=-Wno-incompatible-pointer-types

src/ebt_igmpsnooping.c

@@ -341,8 +341,9 @@ static int igmp_device_event(struct notifier_block *unused, unsigned long event,
 	case NETDEV_CHANGE:
 		if (netif_carrier_ok(dev))
 			return NOTIFY_DONE;
-		 /* fall through */
-	case NETDEV_UNREGISTER: /* fall through */
+		fallthrough;
+	case NETDEV_UNREGISTER:
+		fallthrough;
 	case NETDEV_DOWN:
 		spin_lock_bh(&igmp_lock);
 		list_for_each_safe(cur, next, &igmp_info_list) {

src/ebt_mldsnooping.c

@@ -351,8 +351,9 @@ static int mld_device_event(struct notifier_block *unused, unsigned long event,
 	case NETDEV_CHANGE:
 		if (netif_carrier_ok(dev))
 			return NOTIFY_DONE;
-		 /* fall through */
-	case NETDEV_UNREGISTER: /* fall through */
+		fallthrough;
+	case NETDEV_UNREGISTER:
+		fallthrough;
 	case NETDEV_DOWN:
 		spin_lock_bh(&mld_lock);
 		list_for_each_safe(cur, next, &mld_info_list) {