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To: Bruce Evans <brde@optusnet.com.au>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Wed, 13 Aug 2008 03:23:47 +1000."
	<20080813014505.H1310@besplex.bde.org> 
Date: Tue, 12 Aug 2008 17:28:53 +0000
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Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org,
	Ed Schouten <ed@FreeBSD.org>, cvs-all@FreeBSD.org,
	John Baldwin <jhb@FreeBSD.org>
Subject: Re: cvs commit: src/sys/dev/io iodev.c 
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In message <20080813014505.H1310@besplex.bde.org>, Bruce Evans writes:

>I once thought that using D_TRACKCLOSE was the right fix for this in
>serial drivers.

D_TRACKCLOSE Was created for drivers that need per open state
reclaimation, forced closes is an entirely different kettle of fish.

Writing a driver to support forced closes is significantly more work
than writing a "normal" driver, but it can be eased a lot if we 
add infrastructure to keep track of and wake up all sleeping threads
in a particular driver.

Either way, it is significant architectural work.

Poul-Henning

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.