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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: Piotr Jurkiewicz <piotr.jerzy.jurkiewicz@gmail.com>
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: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yuchung Cheng 2016-08-22 17:17:54 -07:00 committed by David S. Miller
parent 1345b1ac57
commit cebc5cbab4
3 changed files with 32 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

45
Documentation/networking/ip-sysctl.txt
View File

@ -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 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.
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.
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.
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: 1
Default: 0x1
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.
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

3
include/net/tcp.h
View File

@ -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;

21
net/ipv4/af_inet.c
View File

@ -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);
fastopen_queue_tune(sk, backlog);
tcp_fastopen_init_key_once(true);
}
err = inet_csk_listen_start(sk, backlog);
if (err)
goto out;