[NET]: Supporting UDP-Lite (RFC 3828) in Linux

This is a revision of the previously submitted patch, which alters
the way files are organized and compiled in the following manner:

	* UDP and UDP-Lite now use separate object files
	* source file dependencies resolved via header files
	  net/ipv{4,6}/udp_impl.h
	* order of inclusion files in udp.c/udplite.c adapted
	  accordingly

[NET/IPv4]: Support for the UDP-Lite protocol (RFC 3828)

This patch adds support for UDP-Lite to the IPv4 stack, provided as an
extension to the existing UDPv4 code:
        * generic routines are all located in net/ipv4/udp.c
        * UDP-Lite specific routines are in net/ipv4/udplite.c
        * MIB/statistics support in /proc/net/snmp and /proc/net/udplite
        * shared API with extensions for partial checksum coverage

[NET/IPv6]: Extension for UDP-Lite over IPv6

It extends the existing UDPv6 code base with support for UDP-Lite
in the same manner as per UDPv4. In particular,
        * UDPv6 generic and shared code is in net/ipv6/udp.c
        * UDP-Litev6 specific extensions are in net/ipv6/udplite.c
        * MIB/statistics support in /proc/net/snmp6 and /proc/net/udplite6
        * support for IPV6_ADDRFORM
        * aligned the coding style of protocol initialisation with af_inet6.c
        * made the error handling in udpv6_queue_rcv_skb consistent;
          to return `-1' on error on all error cases
        * consolidation of shared code

[NET]: UDP-Lite Documentation and basic XFRM/Netfilter support

The UDP-Lite patch further provides
        * API documentation for UDP-Lite
        * basic xfrm support
        * basic netfilter support for IPv4 and IPv6 (LOG target)

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 3c266ad..9390649 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -158,9 +158,13 @@
 	SNMP_INC_STATS_OFFSET_BH(icmpv6_statistics, field, _offset);    	\
 })
 DECLARE_SNMP_STAT(struct udp_mib, udp_stats_in6);
-#define UDP6_INC_STATS(field)		SNMP_INC_STATS(udp_stats_in6, field)
-#define UDP6_INC_STATS_BH(field)	SNMP_INC_STATS_BH(udp_stats_in6, field)
-#define UDP6_INC_STATS_USER(field) 	SNMP_INC_STATS_USER(udp_stats_in6, field)
+DECLARE_SNMP_STAT(struct udp_mib, udplite_stats_in6);
+#define UDP6_INC_STATS_BH(field, is_udplite) 			      do  {  \
+	if (is_udplite) SNMP_INC_STATS_BH(udplite_stats_in6, field);         \
+	else		SNMP_INC_STATS_BH(udp_stats_in6, field);    } while(0)
+#define UDP6_INC_STATS_USER(field, is_udplite)			       do {    \
+	if (is_udplite) SNMP_INC_STATS_USER(udplite_stats_in6, field);         \
+	else		SNMP_INC_STATS_USER(udp_stats_in6, field);    } while(0)
 
 int snmp6_register_dev(struct inet6_dev *idev);
 int snmp6_unregister_dev(struct inet6_dev *idev);
@@ -604,6 +608,8 @@
 extern void tcp6_proc_exit(void);
 extern int  udp6_proc_init(void);
 extern void udp6_proc_exit(void);
+extern int  udplite6_proc_init(void);
+extern void udplite6_proc_exit(void);
 extern int  ipv6_misc_proc_init(void);
 extern void ipv6_misc_proc_exit(void);