[PATCH net 3/5] fm10k: Implement ndo_gso_check()

[Joe Stringer <joestringer@nicira.com>]

ndo_gso_check() was recently introduced to allow NICs to report the
offloading support that they have on a per-skb basis. Add an
implementation for this driver which checks for something that looks
like VXLAN.

Implementation shamelessly stolen from Tom Herbert:
http://thread.gmane.org/gmane.linux.network/332428/focus=333111

Signed-off-by: Joe Stringer <joestringer@nicira.com>
---
Should this driver report support for GSO on packets with tunnel headers
up to 64B like the i40e driver does?
---
 drivers/net/ethernet/intel/fm10k/fm10k_netdev.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_netdev.c b/drivers/net/ethernet/intel/fm10k/fm10k_netdev.c
index 8811364..b9ef622 100644
--- a/drivers/net/ethernet/intel/fm10k/fm10k_netdev.c
+++ b/drivers/net/ethernet/intel/fm10k/fm10k_netdev.c
@@ -1350,6 +1350,17 @@ static void fm10k_dfwd_del_station(struct net_device *dev, void *priv)
 	}
 }
 
+static bool fm10k_gso_check(struct sk_buff *skb, struct net_device *dev)
+{
+	if ((skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL) &&
+	    (skb->inner_protocol_type != ENCAP_TYPE_ETHER ||
+	     skb->inner_protocol != htons(ETH_P_TEB) ||
+	     skb_inner_mac_header(skb) - skb_transport_header(skb) != 16))
+		return false;
+
+	return true;
+}
+
 static const struct net_device_ops fm10k_netdev_ops = {
 	.ndo_open		= fm10k_open,
 	.ndo_stop		= fm10k_close,
@@ -1372,6 +1383,7 @@ static const struct net_device_ops fm10k_netdev_ops = {
 	.ndo_do_ioctl		= fm10k_ioctl,
 	.ndo_dfwd_add_station	= fm10k_dfwd_add_station,
 	.ndo_dfwd_del_station	= fm10k_dfwd_del_station,
+	.ndo_gso_check		= fm10k_gso_check,
 };
 
 #define DEFAULT_DEBUG_LEVEL_SHIFT 3
-- 
1.7.10.4