tcp: add init_cookie_seq method to tcp_request_sock_ops

Move the specific IPv4/IPv6 cookie sequence initialization to a new
method in tcp_request_sock_ops in preparation for unifying
tcp_v4_conn_request and tcp_v6_conn_request.

Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 7ad8ce2..086d00e 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -495,13 +495,6 @@
 			      u16 *mssp);
 __u32 cookie_v4_init_sequence(struct sock *sk, const struct sk_buff *skb,
 			      __u16 *mss);
-#else
-static inline __u32 cookie_v4_init_sequence(struct sock *sk,
-					    const struct sk_buff *skb,
-					    __u16 *mss)
-{
-	return 0;
-}
 #endif
 
 __u32 cookie_init_timestamp(struct request_sock *req);
@@ -517,13 +510,6 @@
 			      const struct tcphdr *th, u16 *mssp);
 __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
 			      __u16 *mss);
-#else
-static inline __u32 cookie_v6_init_sequence(struct sock *sk,
-					    struct sk_buff *skb,
-					    __u16 *mss)
-{
-	return 0;
-}
 #endif
 /* tcp_output.c */
 
@@ -1615,8 +1601,28 @@
 #endif
 	void (*init_req)(struct request_sock *req, struct sock *sk,
 			 struct sk_buff *skb);
+#ifdef CONFIG_SYN_COOKIES
+	__u32 (*cookie_init_seq)(struct sock *sk, const struct sk_buff *skb,
+				 __u16 *mss);
+#endif
 };
 
+#ifdef CONFIG_SYN_COOKIES
+static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
+					 struct sock *sk, struct sk_buff *skb,
+					 __u16 *mss)
+{
+	return ops->cookie_init_seq(sk, skb, mss);
+}
+#else
+static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
+					 struct sock *sk, struct sk_buff *skb,
+					 __u16 *mss)
+{
+	return 0;
+}
+#endif
+
 int tcpv4_offload_init(void);
 
 void tcp_v4_init(void);