svn commit: r288301 - in head/sys: net netinet netinet6

[Alexander V. Chernikov]

27.09.2015, 15:26, "Bjoern A. Zeeb" <bz at FreeBSD.org>:
> On Sun, 27 Sep 2015, Alexander V. Chernikov wrote:
>
>>  Author: melifaro
>>  Date: Sun Sep 27 05:29:34 2015
>>  New Revision: 288301
>>  URL: https://svnweb.freebsd.org/changeset/base/288301
>>
>>  Log:
>>   Eliminate nd6_nud_hint() and its TCP bindings.
>>
>>   Initially function was introduced in r53541 (KAME initial commit) to
>>     "provide hints from upper layer protocols that indicate a connection
>>     is making "forward progress"" (quote from RFC 2461 7.3.1 Reachability
>>     Confirmation).
>>   However, it was converted to do nothing (e.g. just return) in r122922
>>     (tcp_hostcache implementation) back in 2003. Some defines were moved
>>     to tcp_var.h in r169541. Then, it was broken (for non-corner cases)
>>     by r186119 (L2<>L3 split) in 2008 (NULL ifp in nd6_lookup). So,
>>     right now this code is broken and has no "real" base users.
>>
>>   Differential Revision: https://reviews.freebsd.org/D3699
>
> PR: 165692
>
> It would be nice to have the feature back though it would be very
> expensive locking wise if it'd remain a per-packet operation.
It looks like there are options to implement this without significant overhead (like, on proper TCP session teardown, or on delayed-ack timer, or/and with some sort of sampling + special "no-gw" flag).
I'd prefer not to shift my focus from projects/routing now, but  I can cooperate with someone from TCP side and resurrect/test nd6_nud_hint()

>
> --
> Bjoern A. Zeeb "Come on. Learn, goddamn it.", WarGames, 1983