1 files changed, 38 insertions, 1 deletions

diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index b774a03bd1dc..fc04711e80c8 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -305,6 +305,35 @@ static void tcp_probe_timer(struct sock *sk)
 }
 
 /*
+ *      Timer for Fast Open socket to retransmit SYNACK. Note that the
+ *      sk here is the child socket, not the parent (listener) socket.
+ */
+static void tcp_fastopen_synack_timer(struct sock *sk)
+{
+        struct inet_connection_sock *icsk = inet_csk(sk);
+        int max_retries = icsk->icsk_syn_retries ? :
+            sysctl_tcp_synack_retries + 1; /* add one more retry for fastopen */
+        struct request_sock *req;
+
+        req = tcp_sk(sk)->fastopen_rsk;
+        req->rsk_ops->syn_ack_timeout(sk, req);
+
+        if (req->retrans >= max_retries) {
+                tcp_write_err(sk);
+                return;
+        }
+        /* XXX (TFO) - Unlike regular SYN-ACK retransmit, we ignore error
+         * returned from rtx_syn_ack() to make it more persistent like
+         * regular retransmit because if the child socket has been accepted
+         * it's not good to give up too easily.
+         */
+        req->rsk_ops->rtx_syn_ack(sk, req, NULL);
+        req->retrans++;
+        inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
+                          TCP_TIMEOUT_INIT << req->retrans, TCP_RTO_MAX);
+}
+
+/*
  *      The TCP retransmit timer.
  */
 
@@ -317,7 +346,15 @@ void tcp_retransmit_timer(struct sock *sk)
                 tcp_resume_early_retransmit(sk);
                 return;
         }
-
+        if (tp->fastopen_rsk) {
+                BUG_ON(sk->sk_state != TCP_SYN_RECV &&
+                    sk->sk_state != TCP_FIN_WAIT1);
+                tcp_fastopen_synack_timer(sk);
+                /* Before we receive ACK to our SYN-ACK don't retransmit
+                 * anything else (e.g., data or FIN segments).
+                 */
+                return;
+        }
         if (!tp->packets_out)
                 goto out;