net: Add vxlan_gso_check() helper
Most NICs that report NETIF_F_GSO_UDP_TUNNEL support VXLAN, and not
other UDP-based encapsulation protocols where the format and size of the
header differs. This patch implements a generic ndo_gso_check() for
VXLAN which will only advertise GSO support when the skb looks like it
contains VXLAN (or no UDP tunnelling at all).
Implementation shamelessly stolen from Tom Herbert:
http://thread.gmane.org/gmane.linux.network/332428/focus=333111
Signed-off-by: Joe Stringer <joestringer@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/vxlan.h b/include/net/vxlan.h
index d5f59f3..afadf8e 100644
--- a/include/net/vxlan.h
+++ b/include/net/vxlan.h
@@ -45,6 +45,8 @@
__be32 src, __be32 dst, __u8 tos, __u8 ttl, __be16 df,
__be16 src_port, __be16 dst_port, __be32 vni, bool xnet);
+bool vxlan_gso_check(struct sk_buff *skb);
+
/* IP header + UDP + VXLAN + Ethernet header */
#define VXLAN_HEADROOM (20 + 8 + 8 + 14)
/* IPv6 header + UDP + VXLAN + Ethernet header */