From owner-freebsd-arch@FreeBSD.ORG  Thu Aug 18 18:56:12 2005
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Date: Thu, 18 Aug 2005 11:56:11 -0700
From: Luigi Rizzo <rizzo@icir.org>
To: John Baldwin <jhb@FreeBSD.org>
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	from jhb@FreeBSD.org on Thu, Aug 18, 2005 at 01:12:20PM -0400
Cc: gnn@FreeBSD.org, freebsd-arch@FreeBSD.org
Subject: Re: Special schedulers, one CPU only kernel, one only userland
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On Thu, Aug 18, 2005 at 01:12:20PM -0400, John Baldwin wrote:

[discussion about potential race between foo_detach() and foo_start()]

> > hmmm... it's really tricky to follow. Maybe this does not happen,
> > but i wouldn't know why as fxp_detach() is under giant but the
> > path leading to fxp_start is not...
> 
> ether_ifdetach() should be handling this for us I think by blocking until any 
> known top-half threads are out of the driver.  It may not be doing that yet, 

ok but note that fxp_start could well be called by a bottom-half
thread receiving from a different interface and forwarding to this one.

In any case the detach is probably a very difficult part to fix
because there are references to interfaces all over the place,
and they are not refcounted so we can never know when it is safe to
release memory. At least, so i believe...

	cheers
	luigi