From owner-freebsd-threads@FreeBSD.ORG  Fri Sep 24 15:38:03 2010
Return-Path: <owner-freebsd-threads@FreeBSD.ORG>
Delivered-To: freebsd-threads@freebsd.org
Received: from [127.0.0.1] (freefall.freebsd.org [IPv6:2001:4f8:fff6::28])
	by hub.freebsd.org (Postfix) with ESMTP id 8BEC5106564A;
	Fri, 24 Sep 2010 15:38:03 +0000 (UTC)
	(envelope-from jkim@FreeBSD.org)
From: Jung-uk Kim <jkim@FreeBSD.org>
To: John Baldwin <jhb@freebsd.org>
Date: Fri, 24 Sep 2010 11:37:53 -0400
User-Agent: KMail/1.6.2
References: <201009232220.o8NMK3fX011639@freefall.freebsd.org>
	<201009232348.45201.jkim@FreeBSD.org>
	<201009240926.12958.jhb@freebsd.org>
In-Reply-To: <201009240926.12958.jhb@freebsd.org>
MIME-Version: 1.0
Content-Disposition: inline
Content-Type: text/plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Message-Id: <201009241137.56764.jkim@FreeBSD.org>
Cc: Daniel Eischen <deischen@freebsd.org>, freebsd-threads@freebsd.org
Subject: Re: threads/150889: PTHREAD_MUTEX_INITIALIZER
	+	pthread_mutex_destroy () == EINVAL
X-BeenThere: freebsd-threads@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
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: Fri, 24 Sep 2010 15:38:03 -0000

On Friday 24 September 2010 09:26 am, John Baldwin wrote:
> On Thursday, September 23, 2010 11:48:40 pm Jung-uk Kim wrote:
> > On Thursday 23 September 2010 06:44 pm, Daniel Eischen wrote:
> > > You shouldn't have to call pthread_mutex_init() on a mutex
> > > initialized with PTHREAD_MUTEX_INITIALIZER.  Our implementation
> > > should auto initialize the mutex when it is first used; if it
> > > doesn't, I think that is a bug.
> >
> > Ah, I see.  I verified that libthr does it correctly.  However,
> > that's a hack and it is far from real static allocation although
> > it should work pretty well in reality, IMHO.  More over, it will
> > have a side-effect, i.e., any destroyed mutex may be resurrected
> > if it is used again.  POSIX seems to say it should return EINVAL
> > when it happens. :-(
>
> I think the fix there is that we should put a different value
> ((void *)1 for example) into "destroyed" mutex objects than 0 so
> that destroyed mutexes can be differentiated from statically
> initialized mutexes.  This would also allow us to properly return
> EBUSY, etc.

It would be nice if we had "uninitialized" as (void *)0 and "static 
initializer" as (void *)1.  IMHO, it looks more natural, i.e., 
"uninitialized" or "destroyed" one gets zero, and "dynamically 
initialized" or "statically initialized" one gets non-zero.  Can we 
break the ABI for 9, maybe? ;-)

Jung-uk Kim