Commit cebc5cba authored by Yuchung Cheng's avatar Yuchung Cheng Committed by David S. Miller

net-tcp: retire TFO_SERVER_WO_SOCKOPT2 config

TFO_SERVER_WO_SOCKOPT2 was intended for debugging purposes during
Fast Open development. Remove this config option and also
update/clean-up the documentation of the Fast Open sysctl.
Reported-by: default avatarPiotr Jurkiewicz <piotr.jerzy.jurkiewicz@gmail.com>
Signed-off-by: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1345b1ac
......@@ -575,32 +575,33 @@ tcp_syncookies - BOOLEAN
unconditionally generation of syncookies.
tcp_fastopen - INTEGER
Enable TCP Fast Open feature (draft-ietf-tcpm-fastopen) to send data
in the opening SYN packet. To use this feature, the client application
must use sendmsg() or sendto() with MSG_FASTOPEN flag rather than
connect() to perform a TCP handshake automatically.
Enable TCP Fast Open (RFC7413) to send and accept data in the opening
SYN packet.
The values (bitmap) are
1: Enables sending data in the opening SYN on the client w/ MSG_FASTOPEN.
2: Enables TCP Fast Open on the server side, i.e., allowing data in
a SYN packet to be accepted and passed to the application before
3-way hand shake finishes.
4: Send data in the opening SYN regardless of cookie availability and
without a cookie option.
0x100: Accept SYN data w/o validating the cookie.
0x200: Accept data-in-SYN w/o any cookie option present.
0x400/0x800: Enable Fast Open on all listeners regardless of the
TCP_FASTOPEN socket option. The two different flags designate two
different ways of setting max_qlen without the TCP_FASTOPEN socket
option.
The client support is enabled by flag 0x1 (on by default). The client
then must use sendmsg() or sendto() with the MSG_FASTOPEN flag,
rather than connect() to send data in SYN.
Default: 1
The server support is enabled by flag 0x2 (off by default). Then
either enable for all listeners with another flag (0x400) or
enable individual listeners via TCP_FASTOPEN socket option with
the option value being the length of the syn-data backlog.
Note that the client & server side Fast Open flags (1 and 2
respectively) must be also enabled before the rest of flags can take
effect.
The values (bitmap) are
0x1: (client) enables sending data in the opening SYN on the client.
0x2: (server) enables the server support, i.e., allowing data in
a SYN packet to be accepted and passed to the
application before 3-way handshake finishes.
0x4: (client) send data in the opening SYN regardless of cookie
availability and without a cookie option.
0x200: (server) accept data-in-SYN w/o any cookie option present.
0x400: (server) enable all listeners to support Fast Open by
default without explicit TCP_FASTOPEN socket option.
Default: 0x1
See include/net/tcp.h and the code for more details.
Note that that additional client or server features are only
effective if the basic support (0x1 and 0x2) are enabled respectively.
tcp_syn_retries - INTEGER
Number of times initial SYNs for an active TCP connection attempt
......
......@@ -227,10 +227,9 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
#define TFO_SERVER_COOKIE_NOT_REQD 0x200
/* Force enable TFO on all listeners, i.e., not requiring the
* TCP_FASTOPEN socket option. SOCKOPT1/2 determine how to set max_qlen.
* TCP_FASTOPEN socket option.
*/
#define TFO_SERVER_WO_SOCKOPT1 0x400
#define TFO_SERVER_WO_SOCKOPT2 0x800
extern struct inet_timewait_death_row tcp_death_row;
......
......@@ -211,24 +211,19 @@ 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.
/* Enable TFO w/o requiring TCP_FASTOPEN socket option.
* 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()).
* Also fastopen backlog may already been set via the option
* because the socket was in TCP_LISTEN state previously but
* was shutdown() rather than close().
*/
if ((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) != 0 &&
if ((sysctl_tcp_fastopen & TFO_SERVER_WO_SOCKOPT1) &&
(sysctl_tcp_fastopen & TFO_SERVER_ENABLE) &&
!inet_csk(sk)->icsk_accept_queue.fastopenq.max_qlen) {
if ((sysctl_tcp_fastopen & TFO_SERVER_WO_SOCKOPT1) != 0)
fastopen_queue_tune(sk, backlog);
else if ((sysctl_tcp_fastopen &
TFO_SERVER_WO_SOCKOPT2) != 0)
fastopen_queue_tune(sk,
((uint)sysctl_tcp_fastopen) >> 16);
tcp_fastopen_init_key_once(true);
}
err = inet_csk_listen_start(sk, backlog);
if (err)
goto out;
......
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