Date: Sun, 22 Aug 2010 09:01:58 +0000 (UTC) From: Andre Oppermann <andre@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org Subject: svn commit: r211602 - stable/8/sys/netinet Message-ID: <201008220901.o7M91wZj096649@svn.freebsd.org>
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Author: andre Date: Sun Aug 22 09:01:58 2010 New Revision: 211602 URL: http://svn.freebsd.org/changeset/base/211602 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/8/sys/netinet/tcp_output.c stable/8/sys/netinet/tcp_subr.c Directory Properties: stable/8/sys/ (props changed) stable/8/sys/amd64/include/xen/ (props changed) stable/8/sys/cam/ (props changed) stable/8/sys/cddl/contrib/opensolaris/ (props changed) stable/8/sys/contrib/dev/acpica/ (props changed) stable/8/sys/contrib/pf/ (props changed) stable/8/sys/dev/xen/xenpci/ (props changed) Modified: stable/8/sys/netinet/tcp_output.c ============================================================================== --- stable/8/sys/netinet/tcp_output.c Sun Aug 22 08:47:51 2010 (r211601) +++ stable/8/sys/netinet/tcp_output.c Sun Aug 22 09:01:58 2010 (r211602) @@ -1186,8 +1186,10 @@ 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 (V_path_mtu_discovery) + if (V_path_mtu_discovery && tp->t_maxopd > V_tcp_minmss) ip->ip_off |= IP_DF; error = ip_output(m, tp->t_inpcb->inp_options, NULL, Modified: stable/8/sys/netinet/tcp_subr.c ============================================================================== --- stable/8/sys/netinet/tcp_subr.c Sun Aug 22 08:47:51 2010 (r211601) +++ stable/8/sys/netinet/tcp_subr.c Sun Aug 22 09:01:58 2010 (r211602) @@ -1330,11 +1330,9 @@ tcp_ctlinput(int cmd, struct sockaddr *s if (!mtu) mtu = ip_next_mtu(ip->ip_len, 1); - if (mtu < max(296, V_tcp_minmss - + sizeof(struct tcpiphdr))) - mtu = 0; - if (!mtu) - mtu = V_tcp_mssdflt + if (mtu < V_tcp_minmss + + sizeof(struct tcpiphdr)) + mtu = V_tcp_minmss + sizeof(struct tcpiphdr); /* * Only cache the the MTU if it
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