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>
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 6681ccf..4f70ef0 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -149,6 +149,11 @@
pr_err("Attempt to release alive inet socket %p\n", sk);
return;
}
+ if (sk->sk_type == SOCK_STREAM) {
+ struct fastopen_queue *fastopenq =
+ inet_csk(sk)->icsk_accept_queue.fastopenq;
+ kfree(fastopenq);
+ }
WARN_ON(atomic_read(&sk->sk_rmem_alloc));
WARN_ON(atomic_read(&sk->sk_wmem_alloc));
@@ -212,6 +217,26 @@
* we can only allow the backlog to be adjusted.
*/
if (old_state != TCP_LISTEN) {
+ /* Check special setups for testing purpose to enable TFO w/o
+ * requiring TCP_FASTOPEN sockopt.
+ * Note that only TCP sockets (SOCK_STREAM) will reach here.
+ * Also fastopenq may already been allocated because this
+ * socket was in TCP_LISTEN state previously but was
+ * shutdown() (rather than close()).
+ */
+ if ((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) != 0 &&
+ inet_csk(sk)->icsk_accept_queue.fastopenq == NULL) {
+ if ((sysctl_tcp_fastopen & TFO_SERVER_WO_SOCKOPT1) != 0)
+ err = fastopen_init_queue(sk, backlog);
+ else if ((sysctl_tcp_fastopen &
+ TFO_SERVER_WO_SOCKOPT2) != 0)
+ err = fastopen_init_queue(sk,
+ ((uint)sysctl_tcp_fastopen) >> 16);
+ else
+ err = 0;
+ if (err)
+ goto out;
+ }
err = inet_csk_listen_start(sk, backlog);
if (err)
goto out;
@@ -701,7 +726,8 @@
sock_rps_record_flow(sk2);
WARN_ON(!((1 << sk2->sk_state) &
- (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_CLOSE)));
+ (TCPF_ESTABLISHED | TCPF_SYN_RECV |
+ TCPF_CLOSE_WAIT | TCPF_CLOSE)));
sock_graft(sk2, newsock);
