tcp: properly account Fast Open SYN-ACK retrans

Since the TFO socket is accepted right off SYN-data, the socket
owner can call getsockopt(TCP_INFO) to collect ongoing SYN-ACK
retransmission or timeout stats (i.e., tcpi_total_retrans,
tcpi_retransmits). Currently those stats are only updated
upon handshake completes. This patch fixes it.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 4 insertions, 1 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 3ebf45b38bc3..08323bd95f2a 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5885,7 +5885,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
                  * so release it.
                  */
                 if (req) {
-                        tp->total_retrans = req->num_retrans;
+                        inet_csk(sk)->icsk_retransmits = 0;
                         reqsk_fastopen_remove(sk, req, false);
                 } else {
                         /* Make sure socket is routed, for correct metrics. */
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index e15ec82a6319..5288cec4a2b2 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3568,6 +3568,8 @@ int tcp_rtx_synack(const struct sock *sk, struct request_sock *req)
         if (!res) {
                 __TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS);
                 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS);
+                if (unlikely(tcp_passive_fastopen(sk)))
+                        tcp_sk(sk)->total_retrans++;
         }
         return res;
 }
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index d84930b2dd95..f712b411f6ed 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -384,6 +384,7 @@ static void tcp_fastopen_synack_timer(struct sock *sk)
          */
         inet_rtx_syn_ack(sk, req);
         req->num_timeout++;
+        icsk->icsk_retransmits++;
         inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
                           TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
 }