From owner-freebsd-current@FreeBSD.ORG  Tue Dec  2 13:08:15 2003
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: freebsd-current@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP
	id 2C5FC16A4CE; Tue,  2 Dec 2003 13:08:15 -0800 (PST)
Received: from hak.cnd.mcgill.ca (hak.cnd.mcgill.ca [132.216.11.133])
	by mx1.FreeBSD.org (Postfix) with ESMTP
	id C988C43FE3; Tue,  2 Dec 2003 13:08:12 -0800 (PST)
	(envelope-from mat@hak.cnd.mcgill.ca)
Received: from hak.cnd.mcgill.ca (localhost [127.0.0.1])
	by hak.cnd.mcgill.ca (8.12.9/8.12.8) with ESMTP id hB2L5U15062807;
	Tue, 2 Dec 2003 16:05:30 -0500 (EST)
	(envelope-from mat@hak.cnd.mcgill.ca)
Received: (from mat@localhost)
	by hak.cnd.mcgill.ca (8.12.9/8.12.8/Submit) id hB2L5UiG062806;
	Tue, 2 Dec 2003 16:05:30 -0500 (EST)
Date: Tue, 2 Dec 2003 16:05:30 -0500
From: Mathew Kanner <mat@cnd.mcgill.ca>
To: Maxime Henrion <mux@freebsd.org>
Message-ID: <20031202210530.GG54011@cnd.mcgill.ca>
References: <bq68t8$c8n$2@sea.gmane.org> <bqfgsc$qmu$1@sea.gmane.org>
	<20031201142022.GK8404@elvis.mu.org> <20031201193837.GD49341@cnd.mcgill.ca>
	<20031201230259.GL8404@elvis.mu.org> <20031202203330.GF54011@cnd.mcgill.ca>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20031202203330.GF54011@cnd.mcgill.ca>
User-Agent: Mutt/1.4.1i
Organization: I speak for myself, operating in Montreal, CANADA
X-Spam-Status: No, hits=0.0 required=5.0 tests=none autolearn=no version=2.60
X-Spam-Checker-Version: SpamAssassin 2.60 (1.212-2003-09-23-exp) on 
	hak.cnd.mcgill.ca
cc: freebsd-current@freebsd.org
Subject: Re: 5.2-BETA dsp.c duplicate lock
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 02 Dec 2003 21:08:15 -0000

On Dec 02, Mathew Kanner wrote:
> On Dec 01, Maxime Henrion wrote:
> [snip]
> 	I believe that your patch should fix the problem.  In general
> I see one of three strategies,
> 
> 1)	Your patch,
> 2)	create a new snd_mtxcreate_chan for channels that sets the
> flags DUP_OK.
> 3)	Fix locking to never hold duplicates.  First glance suggests
> that would be contained in dsp.c, the ioctl handler is the real
> problem and seems inconsistent with itself in regards to locking.
> Ugh.

	Why do the best ideas happen after you send?

	4) Make read and write channel locks of a different class.  

	--Mat

-- 
	In general, a standard is very useful, whether it's de facto
	or du jour.
	- Microsoft's Greg Sullivan
	as misquoted by News.Com