atl1e: limit gso segment size to prevent generation of wrong ip length fields

The limit of 0x3c00 is taken from the windows driver.

Suggested-by: Huang, Xiong <xiong@qca.qualcomm.com>
Cc: Huang, Xiong <xiong@qca.qualcomm.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/atheros/atl1e/atl1e.h

@@ -186,7 +186,7 @@ struct atl1e_tpd_desc {
 /* how about 0x2000 */
 #define MAX_TX_BUF_LEN      0x2000
 #define MAX_TX_BUF_SHIFT    13
-/*#define MAX_TX_BUF_LEN  0x3000 */
+#define MAX_TSO_SEG_SIZE    0x3c00
 
 /* rrs word 1 bit 0:31 */
 #define RRS_RX_CSUM_MASK	0xFFFF

drivers/net/ethernet/atheros/atl1e/atl1e_main.c

@@ -2329,6 +2329,7 @@ static int atl1e_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	INIT_WORK(&adapter->reset_task, atl1e_reset_task);
 	INIT_WORK(&adapter->link_chg_task, atl1e_link_chg_task);
+	netif_set_gso_max_size(netdev, MAX_TSO_SEG_SIZE);
 	err = register_netdev(netdev);
 	if (err) {
 		netdev_err(netdev, "register netdevice failed\n");