gre: Allow multiple protocol listener for gre protocol.

Currently there is only one user is allowed to register for gre
protocol.  Following patch adds de-multiplexer.  So that multiple
modules can listen on gre protocol e.g. kernel gre devices and ovs.

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

1 files changed, 24 insertions, 0 deletions

diff --git a/include/net/gre.h b/include/net/gre.h
index 9f03a390c826..c6ea0c72c605 100644
--- a/include/net/gre.h
+++ b/include/net/gre.h
@@ -7,6 +7,7 @@
 #define GREPROTO_CISCO          0
 #define GREPROTO_PPTP           1
 #define GREPROTO_MAX            2
+#define GRE_IP_PROTO_MAX        2
 
 struct gre_protocol {
         int  (*handler)(struct sk_buff *skb);
@@ -22,6 +23,29 @@ struct gre_base_hdr {
 int gre_add_protocol(const struct gre_protocol *proto, u8 version);
 int gre_del_protocol(const struct gre_protocol *proto, u8 version);
 
+struct gre_cisco_protocol {
+        int (*handler)(struct sk_buff *skb, const struct tnl_ptk_info *tpi);
+        int (*err_handler)(struct sk_buff *skb, u32 info,
+                           const struct tnl_ptk_info *tpi);
+        u8 priority;
+};
+
+int gre_cisco_register(struct gre_cisco_protocol *proto);
+int gre_cisco_unregister(struct gre_cisco_protocol *proto);
+
+static inline int ip_gre_calc_hlen(__be16 o_flags)
+{
+        int addend = 4;
+
+        if (o_flags&TUNNEL_CSUM)
+                addend += 4;
+        if (o_flags&TUNNEL_KEY)
+                addend += 4;
+        if (o_flags&TUNNEL_SEQ)
+                addend += 4;
+        return addend;
+}
+
 static inline __be16 gre_flags_to_tnl_flags(__be16 flags)
 {
         __be16 tflags = 0;