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Date:      Fri, 26 Jan 2007 00:23:10 +0300
From:      Gleb Smirnoff <glebius@FreeBSD.org>
To:        Robert Watson <rwatson@FreeBSD.org>
Cc:        "Bruce M. Simpson" <bms@FreeBSD.org>, net@FreeBSD.org
Subject:   Re: rev. 1.94 of netinet/in.c broke CARP
Message-ID:  <20070125212310.GG7922@cell.sick.ru>
In-Reply-To: <20070125203807.S13293@fledge.watson.org>
References:  <20070125162422.GA7922@bestcom.ru> <45B8EB23.705@FreeBSD.org> <20070125183720.GB7922@cell.sick.ru> <20070125203807.S13293@fledge.watson.org>

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On Thu, Jan 25, 2007 at 08:40:52PM +0000, Robert Watson wrote:
R> Architecturally, the right fix is that CARP needs to have a handler for 
R> ifnet destruction that always runs before the multicast address garbage 
R> collection. I'm pretty preoccupied for the next few days due to an 
R> impending paper deadline, so can't investigate further currently, but one 
R> way or the other that ordering dependency needs to be expressed.  If done 
R> properly, CARP will always have released its multicast address before they 
R> are forceably removed. Having the reference count is good too, but what I 
R> describe should be sufficient regardless of the refcount.

This means removing usage of EVENTHANDLER(9) and going back to
exporting carp_ifdetach() and calling it directly from if_detach().
This is back out revision 1.255 of net/if.c. Not sure what is a right
way...

I am worried about that CARP is not the only subsystem in kernel
that can join a multicast group on an ifnet, and keep a pointer
to the multicast instance.

-- 
Totus tuus, Glebius.
GLEBIUS-RIPN GLEB-RIPE



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