From owner-freebsd-threads@FreeBSD.ORG  Tue Oct 25 12:52:18 2005
Return-Path: <owner-freebsd-threads@FreeBSD.ORG>
X-Original-To: freebsd-threads@freebsd.org
Delivered-To: freebsd-threads@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 2F89D16A437;
	Tue, 25 Oct 2005 12:52:18 +0000 (GMT)
	(envelope-from deischen@freebsd.org)
Received: from mail.ntplx.net (mail.ntplx.net [204.213.176.10])
	by mx1.FreeBSD.org (Postfix) with ESMTP id C0E2C43D48;
	Tue, 25 Oct 2005 12:52:17 +0000 (GMT)
	(envelope-from deischen@freebsd.org)
Received: from sea.ntplx.net (sea.ntplx.net [204.213.176.11])
	by mail.ntplx.net (8.13.5/8.13.5/NETPLEX) with ESMTP id j9PCqGYL013213; 
	Tue, 25 Oct 2005 08:52:16 -0400 (EDT)
Date: Tue, 25 Oct 2005 08:52:16 -0400 (EDT)
From: Daniel Eischen <deischen@freebsd.org>
X-X-Sender: eischen@sea.ntplx.net
To: Sven Berkvens-Matthijsse <sven@ilse.net>
In-Reply-To: <20051025071619.GS22568@ilse.net>
Message-ID: <Pine.GSO.4.43.0510250847410.22425-100000@sea.ntplx.net>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
X-Virus-Scanned: by AMaViS and Clam AntiVirus (mail.ntplx.net)
Cc: Marc Olzheim <marcolz@stack.nl>, Marc Olzheim <marcolz@ilse.net>,
	David Xu <davidxu@freebsd.org>, freebsd-threads@freebsd.org
Subject: Re: threads/76690: fork hang in child for (-lc_r & -lthr)
X-BeenThere: freebsd-threads@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
Reply-To: Daniel Eischen <deischen@freebsd.org>
List-Id: Threading on FreeBSD <freebsd-threads.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-threads>, 
	<mailto:freebsd-threads-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-threads>
List-Post: <mailto:freebsd-threads@freebsd.org>
List-Help: <mailto:freebsd-threads-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-threads>,
	<mailto:freebsd-threads-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 25 Oct 2005 12:52:18 -0000

On Tue, 25 Oct 2005, Sven Berkvens-Matthijsse wrote:

> > > But then the free() in the child process may be using an unstable
> > > state of the malloc system (because if you don't acquire the lock
> > > before the fork(), malloc() may be busy in the middle of the
> > > fork()).
> >
> > I don't think that can happen because libc_r will not switch out a
> > thread that is in a critical region (and libc locks are critical
> > regions) until it leaves the region.
>
> What code leads you to that conclusion? All the malloc functions

I had thought that spinlocks and internal mutexes (_pthread_mutex_lock()
called from libc) would mark critical regions.  That was the intent,
but it doesn't seem to be implemented that way in libc_r.  It _is_
implemented that way in libpthread.

-- 
DE