ethernet/intel: use core min/max MTU checking

e100: min_mtu 68, max_mtu 1500
- remove e100_change_mtu entirely, is identical to old eth_change_mtu,
  and no longer serves a purpose. No need to set min_mtu or max_mtu
  explicitly, as ether_setup() will already set them to 68 and 1500.

e1000: min_mtu 46, max_mtu 16110

e1000e: min_mtu 68, max_mtu varies based on adapter

fm10k: min_mtu 68, max_mtu 15342
- remove fm10k_change_mtu entirely, does nothing now

i40e: min_mtu 68, max_mtu 9706

i40evf: min_mtu 68, max_mtu 9706

igb: min_mtu 68, max_mtu 9216
- There are two different "max" frame sizes claimed and both checked in
  the driver, the larger value wasn't relevant though, so I've set max_mtu
  to the smaller of the two values here to retain identical behavior.

igbvf: min_mtu 68, max_mtu 9216
- Same issue as igb duplicated

ixgb: min_mtu 68, max_mtu 16114
- Also remove pointless old == new check, as that's done in dev_set_mtu

ixgbe: min_mtu 68, max_mtu 9710

ixgbevf: min_mtu 68, max_mtu dependent on hardware/firmware
- Some hw can only handle up to max_mtu 1504 on a vf, others 9710

CC: netdev@vger.kernel.org
CC: intel-wired-lan@lists.osuosl.org
CC: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/intel/ixgb/ixgb_main.c b/drivers/net/ethernet/intel/ixgb/ixgb_main.c
index 31f9145..5826b1d 100644
--- a/drivers/net/ethernet/intel/ixgb/ixgb_main.c
+++ b/drivers/net/ethernet/intel/ixgb/ixgb_main.c
@@ -487,6 +487,10 @@ ixgb_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 		netdev->vlan_features |= NETIF_F_HIGHDMA;
 	}
 
+	/* MTU range: 68 - 16114 */
+	netdev->min_mtu = ETH_MIN_MTU;
+	netdev->max_mtu = IXGB_MAX_JUMBO_FRAME_SIZE - ETH_HLEN;
+
 	/* make sure the EEPROM is good */
 
 	if (!ixgb_validate_eeprom_checksum(&adapter->hw)) {
@@ -1619,18 +1623,6 @@ ixgb_change_mtu(struct net_device *netdev, int new_mtu)
 {
 	struct ixgb_adapter *adapter = netdev_priv(netdev);
 	int max_frame = new_mtu + ENET_HEADER_SIZE + ENET_FCS_LENGTH;
-	int old_max_frame = netdev->mtu + ENET_HEADER_SIZE + ENET_FCS_LENGTH;
-
-	/* MTU < 68 is an error for IPv4 traffic, just don't allow it */
-	if ((new_mtu < 68) ||
-	    (max_frame > IXGB_MAX_JUMBO_FRAME_SIZE + ENET_FCS_LENGTH)) {
-		netif_err(adapter, probe, adapter->netdev,
-			  "Invalid MTU setting %d\n", new_mtu);
-		return -EINVAL;
-	}
-
-	if (old_max_frame == max_frame)
-		return 0;
 
 	if (netif_running(netdev))
 		ixgb_down(adapter, true);