From: Damian Lukowski <redacted>
Date: Fri, 29 Jan 2010 23:15:51 +0100

This patches fix the current RTO calculation routine, when
srtt and rttvar are zero, yielding an RTO of zero 
Under some circumstances, TCPs srtt and rttvar are zero,
yielding a calculated RTO of zero.
This is particularly unfortunate for ICMP based RTO recalculation
as introduced in f1ecd5d9e736660 (Revert Backoff [v3]: Revert RTO
on ICMP destination unreachable), as it results in RTO retransmission
flooding.

Thanks to Ilpo Jarvinen for providing debug patches and to
Denys Fedoryshchenko for reporting and testing.

Signed-off-by: Damian Lukowski <redacted>

I still haven't seen a detailed enough analysis of why these
tiny RTOs can come to exist in the first place.

Please show me a list of events, function by function, the value of
relevant variables and per-socket TCP state, in the TCP stack, that
show how this ends up happening.

Thanks for all of your work on this so far.