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Date: Tue, 20 Jul 2004 13:08:54 -0600
From: Scott Long <scottl@samsco.org>
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To: Brian Fundakowski Feldman <green@freebsd.org>
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cc: arch@freebsd.org
cc: Poul-Henning Kamp <phk@phk.freebsd.dk>
Subject: Re: kldunload DIAGNOSTIC idea...
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Brian Fundakowski Feldman wrote:
> On Tue, Jul 20, 2004 at 08:20:23PM +0200, Poul-Henning Kamp wrote:
> 
>>I'm pulling hair out trying to make it guaranteed safe to unload device
>>driver modules, and the major pain here is to make sure there is no
>>thread stuck somewhere inside the code.
>>
>>That gave me the idea for a simple little DIAGNOSTIC check for kldunload:
>>run through the proc/thread table and look for any thread with an
>>instruction counter inside the range of pages we are going to unload.
>>
>>Any takers ?
> 
> 
> You mean any thread with a stack trace that includes an instruction
> counter inside those pages, don't you?
> 

This is better than phk's suggestion since you can have module code
that calls out to another part of the system and blocks.  Still, it's
not 100% perfect.  There are all sorts of APIs out there that do async
callbacks, and it really should be up to the driver to track these
things.

Scott