udp: Add GRO functions to UDP socket

This patch adds GRO functions (gro_receive and gro_complete) to UDP
sockets. udp_gro_receive is changed to perform socket lookup on a
packet. If a socket is found the related GRO functions are called.

This features obsoletes using UDP offload infrastructure for GRO
(udp_offload). This has the advantage of not being limited to provide
offload on a per port basis, GRO is now applied to whatever individual
UDP sockets are bound to.  This also allows the possbility of
"application defined GRO"-- that is we can attach something like
a BPF program to a UDP socket to perfrom GRO on an application
layer protocol.

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/af_inet6.c

@@ -64,6 +64,8 @@
 #include <asm/uaccess.h>
 #include <linux/mroute6.h>
 
+#include "ip6_offload.h"
+
 MODULE_AUTHOR("Cast of dozens");
 MODULE_DESCRIPTION("IPv6 protocol stack for Linux");
 MODULE_LICENSE("GPL");
@@ -959,6 +961,10 @@ static int __init inet6_init(void)
 	if (err)
 		goto udplitev6_fail;
 
+	err = udpv6_offload_init();
+	if (err)
+		goto udpv6_offload_fail;
+
 	err = tcpv6_init();
 	if (err)
 		goto tcpv6_fail;
@@ -988,6 +994,8 @@ pingv6_fail:
 ipv6_packet_fail:
 	tcpv6_exit();
 tcpv6_fail:
+	udpv6_offload_exit();
+udpv6_offload_fail:
 	udplitev6_exit();
 udplitev6_fail:
 	udpv6_exit();