1) If an echoed RFC 1323 time stamp appears to be later than the current time,
ignore it and fall back to old-style RTT calculation. This prevents ending
up with a negative RTT and panicking later.
2) Fix NewReno. This involves a few changes:
a) Implement the send_high variable in RFC 2582. Our implementation is
subtly different; it is one *past* the last sequence number transmitted
rather than being equal to it. This simplifies some logic and makes
the code smaller. Additional logic was required to prevent sequence
number wraparound problems; this is not mentioned in RFC 2582.
b) Make sure we reset t_dupacks on new acks, but *not* on a partial ack.
All of the new ack code is pushed out into tcp_newreno(). (Later this
will probably be a pluggable function.) Thus t_dupacks keeps track of
whether we're in fast recovery all the time, with Reno or NewReno, which
keeps some logic simpler.
c) We do not need to update snd_recover when we're not in fast recovery.
See tech-net for an explanation of this.
d) In the gratuitous fast retransmit prevention case, do not send a packet.
RFC 2582 specifically says that we should "do nothing".
e) Do not inflate the congestion window on a partial ack. (This is done by
testing t_dupacks to see whether we're still in fast recovery.)
This brings the performance of NewReno back up to the same as Reno in a few
random test cases (e.g. transferring peer-to-peer over my wireless network).
I have not concocted a good test case for the behavior specific to NewReno.
support this feature. This avoids multiple crashes that I've had in the
past. Also ensure that packets are not empty when DIAGNOSTIC is set.
However, this is just another sanity check of the received packets, but
does not address the real problem. The issue seems to be the following:
if the card receives data while doing a reset (vr_init), it later finds
a bunch of empty packets in the receive ring.
This explains the crashes I've hit: running a program which needs
promiscuous mode (dhclient) while the card was already running in
that mode (tcpdump). In this situation, it's easy that the second
reset receives stuff from the network.
Unfortunately, I don't know why the card is producing these packets...
While here, fix a typo in a comment.
-because noone should request reads past EOF, or writes past EOF which
are not explicitely marked as file-extending (PGO_PASTEOF), turn
a boundary check into a KASSERT
approved by Chuck Silvers
(should fix build problems w/o COMPAT_16 reported by Markus W Kilbinger
per PR port-mips/29041 and by Havard Eidnes)
-further shuffle COMPAT_* conditionals to allow COMPAT_ULTRIX
w/o COMPAT_16
mycroft