[PATCH net] net: usb: lan78xx : implement .ndo_features_check

[James Hughes <james.hughes@raspberrypi.org>]

As reported by Eric Dumazet, there are still some outstanding
cases where the driver does not handle TSO correctly when skb's
are over a certain size. Most cases have been fixed, this patch
should ensure that forwarded SKB's that are greater than
MAX_SINGLE_PACKET_SIZE - TX_OVERHEAD are software segmented
and handled correctly.

Signed-off-by: James Hughes <james.hughes@raspberrypi.org>
Reported-by: Eric Dumazet <edumazet@google.com>
Cc: Woojung Huh <woojung.huh@microchip.com>
Cc: Microchip Linux Driver Support <UNGLinuxDriver@microchip.com>
---
 drivers/net/usb/lan78xx.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index bc572b921fe1..a01c78d8b9a3 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -31,6 +31,7 @@
 #include <linux/mdio.h>
 #include <linux/phy.h>
 #include <net/ip6_checksum.h>
+#include <net/vxlan.h>
 #include <linux/interrupt.h>
 #include <linux/irqdomain.h>
 #include <linux/irq.h>
@@ -3733,6 +3734,19 @@ static void lan78xx_tx_timeout(struct net_device *net)
  tasklet_schedule(&dev->bh);
 }

+static netdev_features_t lan78xx_features_check(struct sk_buff *skb,
+ struct net_device *netdev,
+ netdev_features_t features)
+{
+ if (skb->len + TX_OVERHEAD > MAX_SINGLE_PACKET_SIZE)
+ features &= ~NETIF_F_GSO_MASK;
+
+ features = vlan_features_check(skb, features);
+ features = vxlan_features_check(skb, features);
+
+ return features;
+}
+
 static const struct net_device_ops lan78xx_netdev_ops = {
  .ndo_open = lan78xx_open,
  .ndo_stop = lan78xx_stop,
@@ -3746,6 +3760,7 @@ static const struct net_device_ops lan78xx_netdev_ops = {
  .ndo_set_features = lan78xx_set_features,
  .ndo_vlan_rx_add_vid = lan78xx_vlan_rx_add_vid,
  .ndo_vlan_rx_kill_vid = lan78xx_vlan_rx_kill_vid,
+ .ndo_features_check = lan78xx_features_check,
 };

 static void lan78xx_stat_monitor(struct timer_list *t)
-- 
2.17.1