tcp: use tcp_v4_send_synack on first SYN-ACK

To avoid large code duplication in IPv6, we need to first simplify
the complicate SYN-ACK sending code in tcp_v4_conn_request().

To use tcp_v4(6)_send_synack() to send all SYN-ACKs, we need to
initialize the mini socket's receive window before trying to
create the child socket and/or building the SYN-ACK packet. So we move
that initialization from tcp_make_synack() to tcp_v4_conn_request()
as a new function tcp_openreq_init_req_rwin().

After this refactoring the SYN-ACK sending code is simpler and easier
to implement Fast Open for IPv6.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Daniel Lee <longinus00@gmail.com>
Signed-off-by: Jerry Chu <hkchu@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 7 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 17d7c6a3d037..f5d6ca4a9d28 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1114,6 +1114,9 @@ static inline void tcp_openreq_init(struct request_sock *req,
         ireq->ir_num = ntohs(tcp_hdr(skb)->dest);
 }
 
+extern void tcp_openreq_init_rwin(struct request_sock *req,
+                                  struct sock *sk, struct dst_entry *dst);
+
 void tcp_enter_memory_pressure(struct sock *sk);
 
 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
@@ -1323,13 +1326,10 @@ void tcp_free_fastopen_req(struct tcp_sock *tp);
 
 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
 int tcp_fastopen_reset_cipher(void *key, unsigned int len);
-int tcp_fastopen_create_child(struct sock *sk,
-                              struct sk_buff *skb,
-                              struct sk_buff *skb_synack,
-                              struct request_sock *req);
-bool tcp_fastopen_check(struct sock *sk, struct sk_buff *skb,
-                        struct request_sock *req,
-                        struct tcp_fastopen_cookie *foc);
+bool tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
+                      struct request_sock *req,
+                      struct tcp_fastopen_cookie *foc,
+                      struct dst_entry *dst);
 void tcp_fastopen_init_key_once(bool publish);
 #define TCP_FASTOPEN_KEY_LENGTH 16