1 files changed, 34 insertions, 1 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index c43eb1a831d7..d9735b76d073 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -533,6 +533,12 @@ unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
 
                 if (tp->urg_data & TCP_URG_VALID)
                         mask |= POLLPRI;
+        } else if (sk->sk_state == TCP_SYN_SENT && inet_sk(sk)->defer_connect) {
+                /* Active TCP fastopen socket with defer_connect
+                 * Return POLLOUT so application can call write()
+                 * in order for kernel to generate SYN+data
+                 */
+                mask |= POLLOUT | POLLWRNORM;
         }
         /* This barrier is coupled with smp_wmb() in tcp_reset() */
         smp_rmb();
@@ -1071,6 +1077,7 @@ static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
                                 int *copied, size_t size)
 {
         struct tcp_sock *tp = tcp_sk(sk);
+        struct inet_sock *inet = inet_sk(sk);
         int err, flags;
 
         if (!(sysctl_tcp_fastopen & TFO_CLIENT_ENABLE))
@@ -1085,9 +1092,19 @@ static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
         tp->fastopen_req->data = msg;
         tp->fastopen_req->size = size;
 
+        if (inet->defer_connect) {
+                err = tcp_connect(sk);
+                /* Same failure procedure as in tcp_v4/6_connect */
+                if (err) {
+                        tcp_set_state(sk, TCP_CLOSE);
+                        inet->inet_dport = 0;
+                        sk->sk_route_caps = 0;
+                }
+        }
         flags = (msg->msg_flags & MSG_DONTWAIT) ? O_NONBLOCK : 0;
         err = __inet_stream_connect(sk->sk_socket, msg->msg_name,
                                     msg->msg_namelen, flags);
+        inet->defer_connect = 0;
         *copied = tp->fastopen_req->copied;
         tcp_free_fastopen_req(tp);
         return err;
@@ -1107,7 +1124,7 @@ int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
         lock_sock(sk);
 
         flags = msg->msg_flags;
-        if (flags & MSG_FASTOPEN) {
+        if (unlikely(flags & MSG_FASTOPEN || inet_sk(sk)->defer_connect)) {
                 err = tcp_sendmsg_fastopen(sk, msg, &copied_syn, size);
                 if (err == -EINPROGRESS && copied_syn > 0)
                         goto out;
@@ -2656,6 +2673,18 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
                         err = -EINVAL;
                 }
                 break;
+        case TCP_FASTOPEN_CONNECT:
+                if (val > 1 || val < 0) {
+                        err = -EINVAL;
+                } else if (sysctl_tcp_fastopen & TFO_CLIENT_ENABLE) {
+                        if (sk->sk_state == TCP_CLOSE)
+                                tp->fastopen_connect = val;
+                        else
+                                err = -EINVAL;
+                } else {
+                        err = -EOPNOTSUPP;
+                }
+                break;
         case TCP_TIMESTAMP:
                 if (!tp->repair)
                         err = -EPERM;
@@ -3016,6 +3045,10 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
                 val = icsk->icsk_accept_queue.fastopenq.max_qlen;
                 break;
 
+        case TCP_FASTOPEN_CONNECT:
+                val = tp->fastopen_connect;
+                break;
+
         case TCP_TIMESTAMP:
                 val = tcp_time_stamp + tp->tsoffset;
                 break;