From owner-freebsd-current@FreeBSD.ORG Fri Mar 26 15:53:42 2004 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id C63A916A4CE; Fri, 26 Mar 2004 15:53:42 -0800 (PST) Received: from mail.pcnet.com (mail.pcnet.com [204.213.232.4]) by mx1.FreeBSD.org (Postfix) with ESMTP id 826E443D1D; Fri, 26 Mar 2004 15:53:42 -0800 (PST) (envelope-from eischen@vigrid.com) Received: from mail.pcnet.com (mail.pcnet.com [204.213.232.4]) by mail.pcnet.com (8.12.10/8.12.1) with ESMTP id i2QNrftf027526; Fri, 26 Mar 2004 18:53:41 -0500 (EST) Date: Fri, 26 Mar 2004 18:53:41 -0500 (EST) From: Daniel Eischen X-Sender: eischen@pcnet5.pcnet.com To: Sean McNeil In-Reply-To: <1080344625.82158.35.camel@server.mcneil.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: "Jacques A. Vidrine" cc: freebsd-current@freebsd.org Subject: Re: nss_ldap broken X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 26 Mar 2004 23:53:42 -0000 On Fri, 26 Mar 2004, Sean McNeil wrote: > > On Fri, 2004-03-26 at 14:51, Daniel Eischen wrote: > > > > I think I made a comment about how you should always > > prefix _pthread_foo() calls with 'if (__isthreaded)'. > > > > When the thread libraries are initialized, then overrwrite > > the function pointers in libc's thread jumptable. If you > > unload the library, libc still retains those pointers. > > Yes, checking __isthreaded solves my problem. nsdispatch.c has several > calls to _thread* routines that should be protected by the __isthreaded > test. > > It would appear that even though RTLD_LOCAL is used on the dlopen, since > nss_ldap.so.1 is linked with libc as well it causes those thread > jumptable entries to be modified. When dlclose is called the reference > count to the thread library goes to zero, the library is unloaded, and > the pointers are now no good. > > This poses an interesting problem, though. Since there is a dlopen in > this it is possible for part of a function to have __isthreaded not set > and part of it set. For these routines the value of __isthreaded would > need to be stashed. Yet for the nss_atexit, since it is the opposite > direction (dlclose), the variable would have to be tested directly. Once something is threaded, I think it always has to be threaded. We don't support going back to unthreaded mode. I'm not sure how all this works with nss_ldap (and perhaps other modules) and why they are bringing in the threads library. What dependency is bringing in the threads library in the first place? -- Dan Eischen