From owner-cvs-src@FreeBSD.ORG  Sun May 25 16:34:36 2003
Return-Path: <owner-cvs-src@FreeBSD.ORG>
Delivered-To: cvs-src@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP
	id 7D8C337B401; Sun, 25 May 2003 16:34:36 -0700 (PDT)
Received: from mail.chesapeake.net (chesapeake.net [208.142.252.6])
	by mx1.FreeBSD.org (Postfix) with ESMTP
	id 6642443F3F; Sun, 25 May 2003 16:34:35 -0700 (PDT)
	(envelope-from jroberson@chesapeake.net)
Received: from localhost (jroberson@localhost)
	by mail.chesapeake.net (8.11.6/8.11.6) with ESMTP id h4PNYYc53810;
	Sun, 25 May 2003 19:34:34 -0400 (EDT)
	(envelope-from jroberson@chesapeake.net)
From: Jeff Roberson <jroberson@chesapeake.net>
To: "Alan L. Cox" <alc@imimic.com>
In-Reply-To: <3ED13356.652D9C44@imimic.com>
Message-ID: <20030525193333.Q69975-100000@mail.chesapeake.net>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
cc: cvs-src@FreeBSD.org
cc: Jeff Roberson <jeff@FreeBSD.org>
cc: src-committers@FreeBSD.org
cc: cvs-all@FreeBSD.org
Subject: Re: cvs commit: src/sys/kern kern_umtx.c
X-BeenThere: cvs-src@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: CVS commit messages for the src tree <cvs-src.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/cvs-src>,
	<mailto:cvs-src-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/cvs-src>
List-Post: <mailto:cvs-src@freebsd.org>
List-Help: <mailto:cvs-src-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/cvs-src>,
	<mailto:cvs-src-request@freebsd.org?subject=subscribe>
Date: Sun, 25 May 2003 23:34:36 -0000
X-Original-Date: Sun, 25 May 2003 19:34:34 -0400 (EDT)
X-List-Received-Date: Sun, 25 May 2003 23:34:36 -0000

On Sun, 25 May 2003, Alan L. Cox wrote:

> Jeff Roberson wrote:
> >
> > jeff        2003/05/25 11:18:32 PDT
> >
> >   FreeBSD src repository
> >
> >   Modified files:
> >     sys/kern             kern_umtx.c
> >   Log:
> >    - Create a new lock, umtx_lock, for use instead of the proc lock for
> >      protecting the umtx queues.  We can't use the proc lock because we need
> >      to hold the lock across calls to casuptr, which can fault.
> >
> >   Approved by:    re
> >
> >   Revision  Changes    Path
> >   1.3       +13 -6     src/sys/kern/kern_umtx.c
>
> In general, we can sleep on a fault.  Thus, you could be holding this
> mutex at the time of a sleep.
>

That was just pointed out to me.  This patch at least makes things
slightly more correct.

I'm going to have to look at the problem a little closer to see if I can
implement this code without holding a lock across the casuptr.  otherwise
I'll have to use sx.

Cheers,
Jeff