Revert 7233d971918e "[netdrv] intel: use core min/max MTU checking" (upstream
91c527a55664), as network stack in 7.4 uses the old ndo_change_mtu method.
Index: src/drivers/net/ethernet/intel/i40evf/i40evf_main.c
===================================================================
--- src.orig/drivers/net/ethernet/intel/i40evf/i40evf_main.c	2018-02-27 18:31:41.909916904 +0100
+++ src/drivers/net/ethernet/intel/i40evf/i40evf_main.c	2018-02-27 18:34:29.982151356 +0100
@@ -2333,6 +2333,10 @@
 static int i40evf_change_mtu(struct net_device *netdev, int new_mtu)
 {
 	struct i40evf_adapter *adapter = netdev_priv(netdev);
+	int max_frame = new_mtu + ETH_HLEN + ETH_FCS_LEN;
+
+	if ((new_mtu < 68) || (max_frame > I40E_MAX_RXBUFFER))
+		return -EINVAL;
 
 	netdev->mtu = new_mtu;
 	if (CLIENT_ENABLED(adapter)) {
@@ -2453,7 +2457,7 @@
 	.ndo_set_rx_mode	= i40evf_set_rx_mode,
 	.ndo_validate_addr	= eth_validate_addr,
 	.ndo_set_mac_address	= i40evf_set_mac,
-	.extended.ndo_change_mtu	= i40evf_change_mtu,
+	.ndo_change_mtu_rh74	= i40evf_change_mtu,
 	.ndo_tx_timeout		= i40evf_tx_timeout,
 	.ndo_vlan_rx_add_vid	= i40evf_vlan_rx_add_vid,
 	.ndo_vlan_rx_kill_vid	= i40evf_vlan_rx_kill_vid,
@@ -2734,10 +2738,6 @@
 	i40evf_set_ethtool_ops(netdev);
 	netdev->watchdog_timeo = 5 * HZ;
 
-	/* MTU range: 68 - 9710 */
-	netdev->extended->min_mtu = ETH_MIN_MTU;
-	netdev->extended->max_mtu = I40E_MAX_RXBUFFER - (ETH_HLEN + ETH_FCS_LEN);
-
 	if (!is_valid_ether_addr(adapter->hw.mac.addr)) {
 		dev_info(&pdev->dev, "Invalid MAC address %pM, using random\n",
 			 adapter->hw.mac.addr);