From owner-freebsd-current@FreeBSD.ORG  Wed Nov 29 22:32:59 2006
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
X-Original-To: freebsd-current@freebsd.org
Delivered-To: freebsd-current@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id 2E45016A415;
	Wed, 29 Nov 2006 22:32:59 +0000 (UTC)
	(envelope-from jb@what-creek.com)
Received: from what-creek.com (what-creek.com [66.111.37.70])
	by mx1.FreeBSD.org (Postfix) with ESMTP id D588043D53;
	Wed, 29 Nov 2006 22:31:21 +0000 (GMT)
	(envelope-from jb@what-creek.com)
Received: by what-creek.com (Postfix, from userid 102)
	id 67D7C140EC03; Wed, 29 Nov 2006 22:32:21 +0000 (GMT)
Date: Wed, 29 Nov 2006 22:32:21 +0000
From: John Birrell <jb@what-creek.com>
To: John Baldwin <jhb@freebsd.org>
Message-ID: <20061129223221.GA359@what-creek.com>
References: <45622068.2050705@student.tue.nl>
	<200611291204.03716.jhb@freebsd.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <200611291204.03716.jhb@freebsd.org>
User-Agent: Mutt/1.4.2.1i
Cc: jb@freebsd.org, freebsd-current@freebsd.org,
	Rene Ladan <r.c.ladan@gmail.com>
Subject: Re: calcru-triggered panic?
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.5
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: Wed, 29 Nov 2006 22:32:59 -0000

On Wed, Nov 29, 2006 at 12:04:03PM -0500, John Baldwin wrote:
> On Monday 20 November 2006 16:38, Rene Ladan wrote:
> > Hi,
> > 
> > I got the attached panic on CURRENT 2006-11-17.
> > 
> > It was preceded by a lot of 'calcru' messages.
> 
> The calcru messages you can ignore.
> 
> This is the real problem:
> 
> panic: blockable sleep lock (sleep mutex) tty 
> @ /usr/src-current/sys/kern/kern_event.c:1670
> 
> This panic is due to the recent changes to printf to try to buffer the printf 
> output.  It now runs cnputc() under a critical section and syscons(4) tries 
> to do a ttwakeup() which invokes KNOTE() and tries to lock a regular mutex 
> while inside the critical section.  I'm not sure how best to fix this.

I would like to go back to using a printf buffer on the stack
(like I had in my original implementation). The downside of
doing that is that it places more stress on the stack and for
things like cam, that is an issue, so I am told.

--
John Birrell