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Change net.inet.tcp.ecn.enable sysctl mib from a binary off/on

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control to a three way setting.
  0 - Totally disable ECN. (no change)
  1 - Enable ECN if incoming connections request it.  Outgoing
      connections will request ECN.  (no change from present != 0 setting)
  2 - Enable ECN if incoming connections request it.  Outgoing
      conections will not request ECN.

Change the default value of net.inet.tcp.ecn.enable from 0 to 2.

Linux version 2.4.20 and newer, Solaris, and Mac OS X 10.5 and newer have
similar capabilities.  The actual values above match Linux, and the default
matches the current Linux default.

Reviewed by:	eadler
MFC after:	1 month
MFH:		yes
Sponsored by:	https://reviews.freebsd.org/D6386
This commit is contained in:
Don Lewis 2016-05-19 22:20:35 +00:00
parent 0587ad6b48
commit 883054b4c3
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=300240
2 changed files with 2 additions and 2 deletions
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2
sys/netinet/tcp_input.c
View File

@ -185,7 +185,7 @@ SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc_l_var, CTLFLAG_VNET | CTLFLAG_RW,
static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, ecn, CTLFLAG_RW, 0, "TCP ECN");
VNET_DEFINE(int, tcp_do_ecn) = 0;
VNET_DEFINE(int, tcp_do_ecn) = 2;
SYSCTL_INT(_net_inet_tcp_ecn, OID_AUTO, enable, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(tcp_do_ecn), 0,
"TCP ECN support");

2
sys/netinet/tcp_output.c
View File

@ -1117,7 +1117,7 @@ tcp_output(struct tcpcb *tp)
* resend those bits a number of times as per
* RFC 3168.
*/
if (tp->t_state == TCPS_SYN_SENT && V_tcp_do_ecn) {
if (tp->t_state == TCPS_SYN_SENT && V_tcp_do_ecn == 1) {
if (tp->t_rxtshift >= 1) {
if (tp->t_rxtshift <= V_tcp_ecn_maxretries)
flags |= TH_ECE|TH_CWR;