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Date:      Tue, 10 Jul 2012 12:03:36 +0700
From:      Eugene Grosbein <egrosbein@rdtc.ru>
To:        Ryan Stone <rysto32@gmail.com>
Cc:        bzeeb-lists@lists.zabbadoz.net, Przemyslaw Frasunek <venglin@freebsd.lublin.pl>, Mike Tancsa <mike@sentex.net>, freebsd-net@freebsd.org
Subject:   Re: mpd5/Netgraph issues after upgrading to 7.4
Message-ID:  <4FFBB7A8.90201@rdtc.ru>
In-Reply-To: <CAFMmRNydo=Bci=WM5mODS0vhiv8%2B2Oj39XKTXkEymYOJunhPxg@mail.gmail.com>
References:  <20110513162311.GK95084@glebius.int.ru>	<4DD298AD.2060905@frasunek.com>	<20110517184613.GN74366@glebius.int.ru>	<4FDB1D71.6050908@freebsd.lublin.pl>	<20120615203142.GW28613@glebius.int.ru>	<4FDBAFD7.9020606@freebsd.lublin.pl>	<4FDF2F81.6030307@sentex.net>	<4FDF3097.6080701@freebsd.lublin.pl>	<4FE0EE62.5070905@freebsd.lublin.pl>	<4FF7F2C6.5070401@freebsd.lublin.pl>	<20120709081225.GJ21957@glebius.int.ru> <CAFMmRNydo=Bci=WM5mODS0vhiv8%2B2Oj39XKTXkEymYOJunhPxg@mail.gmail.com>

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10.07.2012 03:25, Ryan Stone пишет:
> On Mon, Jul 9, 2012 at 4:12 AM, Gleb Smirnoff <glebius@freebsd.org> wrote:
>> This looks very much related to a known race in ARP code.
>>
>> See this email and related thread:
>>
>> http://lists.freebsd.org/pipermail/freebsd-net/2012-March/031865.html
>>
>> Ryan didn't check in any patches since, and I failed to follow on this
>> problem due to ENOTIME.
>>
>> I've added Ryan to Cc. Ryan, what's the status of the problem at your
>> side? Did you come to any solution?
> 
> Unfortunately I was never able to come to a satisfactory solution.  As
> I recall, in the end I ran headlong into problems with making the
> locking sane.  The big problem was with arpresolve.  At one point it
> calls callout_reset to schedule the LLE's la_timer.  In my patch this
> would have to be done with a write lock help on the afdata lock.
> However, this acquisition would have to be done before taking the
> LLE_LOCK to prevent a LOR, and in the end you conclude that you have
> to take a write lock on the ifnet's afdata lock for every packet that
> goes through arpresolve, which was a non-starter.  That's the point
> that I reached before I got distracted by other things at $WORK.
> 
> As I recall, the in6 case was even worse, as the in6 equivalent of
> arptimer is significantly more complicated and likes to do crazy
> things like dropping locks.

It seems, Przemyslaw Frasunek uses proxyarp?
I have no such problems but I do not use proxyarp.
Could you get rid of it, Przemyslaw?

Eugene Grosbein




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