From owner-freebsd-hackers@FreeBSD.ORG  Fri Mar 24 10:46:14 2006
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
X-Original-To: freebsd-hackers@freebsd.org
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 2FB4F16A41F;
	Fri, 24 Mar 2006 10:46:14 +0000 (UTC)
	(envelope-from davidxu@freebsd.org)
Received: from freefall.freebsd.org (freefall.freebsd.org [216.136.204.21])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 3C52243D55;
	Fri, 24 Mar 2006 10:46:13 +0000 (GMT)
	(envelope-from davidxu@freebsd.org)
Received: from localhost.my.domain (root@localhost [127.0.0.1])
	by freefall.freebsd.org (8.13.4/8.13.4) with ESMTP id k2OAk9E2079676;
	Fri, 24 Mar 2006 10:46:10 GMT (envelope-from davidxu@freebsd.org)
From: David Xu <davidxu@freebsd.org>
To: freebsd-threads@freebsd.org
Date: Fri, 24 Mar 2006 18:46:00 +0800
User-Agent: KMail/1.8.2
References: <44215FE9.2070602@highway.ne.jp>
	<20060323105440.GD27116@deviant.kiev.zoral.com.ua>
	<20060324084834.GE27116@deviant.kiev.zoral.com.ua>
In-Reply-To: <20060324084834.GE27116@deviant.kiev.zoral.com.ua>
MIME-Version: 1.0
Content-Type: text/plain;
  charset="gb2312"
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline
Message-Id: <200603241846.00579.davidxu@freebsd.org>
Cc: Kostik Belousov <kostikbel@gmail.com>, freebsd-hackers@freebsd.org
Subject: Re: [patch] Re: dlopen() and dlclose() are not MT-safe? YES,
	esp. for libthr
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>, 
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 24 Mar 2006 10:46:14 -0000

=D4=DA Friday 24 March 2006 16:48=A3=ACKostik Belousov =D0=B4=B5=C0=A3=BA
> I did understand the purpose of the thread mask code in
> libexec/rtld/rtld_lock.c, or, more precisely, the condition where this co=
de
> works (for the context, see the mails with same subject on freebsd-hacker=
s).
>=20
> Look, that code assumes that blocking async signals would stop thread
> scheduler from doing preemption of the current thread. This works
> for libc_r, but fails in libpthread and libthr cases. libpthread provides
> implementation of the locks for rtld. But libthr does not !
>=20
> As result, rtld exhibit races when used with libthr. In other words,
> libthr needs code to do proper locking.
>=20
> Do you agree ? Does somebody already planned to do this work ?
>=20
> Best regards,
> Kostik Belousov
>=20
I will check libthr source code to see if I can fix it at the weekend.

David Xu