-stable review patch. If anyone has any objections, please let us know. ------------------ From: Stephen Hemminger There are black box devices out there, routers and firewalls and whatnot, that simply cannot grok the TCP window scaling option correctly. People should and do bark at the site running the device causing the problems, but in the mean time folks do want a way to deal with the problem. We don't want them to turn off window scaling completely as that hurts performance of connections that would run just fine with window scaling enabled. So give a way to do this on a per-route basis by limiting the window scaling by the per-connection window clamp. Stephen's changelog message explains how to do this using a route metric. [TCP]: Limit window scaling if window is clamped. This small change allows for easy per-route workarounds for broken hosts or middleboxes that are not compliant with TCP standards for window scaling. Rather than having to turn off window scaling globally. This patch allows reducing or disabling window scaling if window clamp is present. Example: Mark Lord reported a problem with 2.6.17 kernel being unable to access http://www.everymac.com # ip route add 216.145.246.23/32 via 10.8.0.1 window 65535 Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_output.c | 1 + 1 file changed, 1 insertion(+) --- linux-2.6.17.11.orig/net/ipv4/tcp_output.c +++ linux-2.6.17.11/net/ipv4/tcp_output.c @@ -197,6 +197,7 @@ void tcp_select_initial_window(int __spa * See RFC1323 for an explanation of the limit to 14 */ space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max); + space = min_t(u32, space, *window_clamp); while (space > 65535 && (*rcv_wscale) < 14) { space >>= 1; (*rcv_wscale)++; -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/