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authorJerry Chu <hkchu@google.com>2012-08-31 12:29:12 +0000
committerDavid S. Miller <davem@davemloft.net>2012-08-31 20:02:19 -0400
commit8336886f786fdacbc19b719c1f7ea91eb70706d4 (patch)
treec1fa912f7583ce0ffcb5ae673802da4a7dfb3b19 /net/ipv4/tcp_timer.c
parent1046716368979dee857a2b8a91c4a8833f21b9cb (diff)
downloadlinux-8336886f786fdacbc19b719c1f7ea91eb70706d4.tar.bz2
tcp: TCP Fast Open Server - support TFO listeners
This patch builds on top of the previous patch to add the support for TFO listeners. This includes - 1. allocating, properly initializing, and managing the per listener fastopen_queue structure when TFO is enabled 2. changes to the inet_csk_accept code to support TFO. E.g., the request_sock can no longer be freed upon accept(), not until 3WHS finishes 3. allowing a TCP_SYN_RECV socket to properly poll() and sendmsg() if it's a TFO socket 4. properly closing a TFO listener, and a TFO socket before 3WHS finishes 5. supporting TCP_FASTOPEN socket option 6. modifying tcp_check_req() to use to check a TFO socket as well as request_sock 7. supporting TCP's TFO cookie option 8. adding a new SYN-ACK retransmit handler to use the timer directly off the TFO socket rather than the listener socket. Note that TFO server side will not retransmit anything other than SYN-ACK until the 3WHS is completed. The patch also contains an important function "reqsk_fastopen_remove()" to manage the somewhat complex relation between a listener, its request_sock, and the corresponding child socket. See the comment above the function for the detail. Signed-off-by: H.K. Jerry Chu <hkchu@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Tom Herbert <therbert@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_timer.c')
-rw-r--r--net/ipv4/tcp_timer.c39
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;