Author: andre
Date: Sun Aug 22 09:02:38 2010
New Revision: 211603
URL: http://svn.freebsd.org/changeset/base/211603
Log:
MFC r211333:
Fix the interaction between 'ICMP fragmentation needed' MTU updates,
path MTU discovery and the tcp_minmss limiter for very small MTU's.
Modified:
stable/7/sys/netinet/tcp_output.c
stable/7/sys/netinet/tcp_subr.c
Directory Properties:
stable/7/sys/ (props changed)
stable/7/sys/cddl/contrib/opensolaris/ (props changed)
stable/7/sys/contrib/dev/acpica/ (props changed)
stable/7/sys/contrib/pf/ (props changed)
Modified: stable/7/sys/netinet/tcp_output.c
==============================================================================
--- stable/7/sys/netinet/tcp_output.c Sun Aug 22 09:01:58 2010
(r211602)
+++ stable/7/sys/netinet/tcp_output.c Sun Aug 22 09:02:38 2010
(r211603)
@@ -1130,8 +1130,10 @@ timer:
* This might not be the best thing to do according to RFC3390
* Section 2. However the tcp hostcache migitates the problem
* so it affects only the first tcp connection with a host.
+ *
+ * NB: Don't set DF on small MTU/MSS to have a safe fallback.
*/
- if (path_mtu_discovery)
+ if (path_mtu_discovery && tp->t_maxopd > tcp_minmss)
ip->ip_off |= IP_DF;
error = ip_output(m, tp->t_inpcb->inp_options, NULL,
Modified: stable/7/sys/netinet/tcp_subr.c
==============================================================================
--- stable/7/sys/netinet/tcp_subr.c Sun Aug 22 09:01:58 2010
(r211602)
+++ stable/7/sys/netinet/tcp_subr.c Sun Aug 22 09:02:38 2010
(r211603)
@@ -1241,11 +1241,9 @@ tcp_ctlinput(int cmd, struct sockaddr *s
if (!mtu)
mtu = ip_next_mtu(ip->ip_len,
1);
- if (mtu < max(296, (tcp_minmss)
- + sizeof(struct tcpiphdr)))
- mtu = 0;
- if (!mtu)
- mtu = tcp_mssdflt
+ if (mtu < tcp_minmss
+ + sizeof(struct tcpiphdr))
+ mtu = tcp_minmss
+ sizeof(struct tcpiphdr);
/*
* Only cache the the MTU if it
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