GRE: Refactor GRE tunneling code.

Following patch refactors GRE code into ip tunneling code and GRE
specific code. Common tunneling code is moved to ip_tunnel module.
ip_tunnel module is written as generic library which can be used
by different tunneling implementations.

ip_tunnel module contains following components:
 - packet xmit and rcv generic code. xmit flow looks like
   (gre_xmit/ipip_xmit)->ip_tunnel_xmit->ip_local_out.
 - hash table of all devices.
 - lookup for tunnel devices.
 - control plane operations like device create, destroy, ioctl, netlink
   operations code.
 - registration for tunneling modules, like gre, ipip etc.
 - define single pcpu_tstats dev->tstats.
 - struct tnl_ptk_info added to pass parsed tunnel packet parameters.

ipip.h header is renamed to ip_tunnel.h

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 0 deletions

diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index 7944df768454..2073226a8a63 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -186,9 +186,14 @@ config NET_IPGRE_DEMUX
          This is helper module to demultiplex GRE packets on GRE version field criteria.
          Required by ip_gre and pptp modules.
 
+config NET_IP_TUNNEL
+        tristate
+        default n
+
 config NET_IPGRE
         tristate "IP: GRE tunnels over IP"
         depends on (IPV6 || IPV6=n) && NET_IPGRE_DEMUX
+        select NET_IP_TUNNEL
         help
           Tunneling means encapsulating data of one protocol type within
           another protocol and sending it over a channel that understands the