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tcp: TCP Fast Open Server - support TFO listeners

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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>
This commit is contained in:
Jerry Chu
2012-08-31 12:29:12 +00:00
committed by David S. Miller
parent 1046716368
commit 8336886f78
13 changed files with 329 additions and 49 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
net/ipv4/af_inet.c
View File

@@ -149,6 +149,11 @@ void inet_sock_destruct(struct sock *sk)
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 @@ int inet_listen(struct socket *sock, int backlog)
* 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 @@ int inet_accept(struct socket *sock, struct socket *newsock, int flags)
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);