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Date: Tue, 19 Oct 2004 18:54:53 -0400 (EDT)
From: Robert Watson <rwatson@freebsd.org>
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To: Andre Oppermann <andre@freebsd.org>
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Subject: Re: cvs commit: src/sys/netinet ip_divert.c
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On Wed, 20 Oct 2004, Andre Oppermann wrote:

> Robert Watson wrote:
> > 
> > On Wed, 20 Oct 2004, Andre Oppermann wrote:
> > 
> > > Hmm... I'll take a look at those attempts and see what I can come up
> > > with to get some general solution for the protocol cases.  The approach
> > > of callout_drain() looks promising though.
> > 
> > BTW, it looks like the divert pcb zone uses UMA_ZONE_NOFREE so that the
> > memory is type-stable (presumably in particular for the sysctl), so all
> > memory allocated by the divert module for pcbs is likely leaked on unload.
> > I'm beginning to think we should just block unload for divert and solve
> > the unload problem another day for another protocol...
> 
> It is indeed an oversight by me not to uma_zdestroy() the zone on
> unload.  The sysctl handler uses normal malloc. 

If it's like other instances of type-stable storage, it's so that weak
consistency can be used by the monitoring sysctl in order to avoid
allocating lots of memory and/or suspending operation while monitoring
takes place.  Other instances of type-stable storage in the socket code
and network stack rely on the "chain'o'pcbs" list pointers not being
cleared on allocation and free. 

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org      Principal Research Scientist, McAfee Research