From owner-freebsd-threads@FreeBSD.ORG Sun Apr 17 15:42:07 2011 Return-Path: Delivered-To: freebsd-threads@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D4F6E1065672; Sun, 17 Apr 2011 15:42:07 +0000 (UTC) (envelope-from eischen@vigrid.com) Received: from mail.netplex.net (mail.netplex.net [204.213.176.10]) by mx1.freebsd.org (Postfix) with ESMTP id 8E4A28FC0C; Sun, 17 Apr 2011 15:42:07 +0000 (UTC) Received: from sea.ntplx.net (sea.ntplx.net [204.213.176.11]) by mail.netplex.net (8.14.4/8.14.4/NETPLEX) with ESMTP id p3HFL7Um024525; Sun, 17 Apr 2011 11:21:07 -0400 X-Virus-Scanned: by AMaViS and Clam AntiVirus (mail.netplex.net) X-Greylist: Message whitelisted by DRAC access database, not delayed by milter-greylist-4.2.6 (mail.netplex.net [204.213.176.10]); Sun, 17 Apr 2011 11:21:07 -0400 (EDT) Date: Sun, 17 Apr 2011 11:21:07 -0400 (EDT) From: Daniel Eischen X-X-Sender: eischen@sea.ntplx.net To: Andriy Gapon In-Reply-To: <4DAAFBAF.90700@FreeBSD.org> Message-ID: References: <4DA98197.8060104@FreeBSD.org> <4DAAFBAF.90700@FreeBSD.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: hackers@freebsd.org, freebsd-threads@freebsd.org Subject: Re: puzzled: fork +libthr X-BeenThere: freebsd-threads@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Threading on FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 17 Apr 2011 15:42:07 -0000 On Sun, 17 Apr 2011, Andriy Gapon wrote: > on 16/04/2011 14:46 Andriy Gapon said the following: >> The second puzzle is the EPERM return value itself, on stable/8. >> From what I seem chromium does a bunch of forks before it gets to the place of >> interest. My debugging shows that those forks are "single-threaded" (i.e. code >> in thr_fork.c is not called). And then in a process/thread that makes that >> pthread_cond_wait call I see that libthr and kernel have different opinions >> about what current TID is. Userland part uses what is actually a kernel TID of >> its parent thread (the one that called fork). And given how the work is divided >> between userland and kernel in libthr, that mismatch leads to serious consequences. >> >> So my question is why libthr doesn't see its actual TID. Maybe some >> initialization code is not invoked. BTW, chromium is linked to both libc and >> libthr (per ldd). But it seems that there are no pthread calls up the fork >> chain until that pthread_cond_wait call. > > The second problem seems to be caused by chrome binary being linked to libc and > libthr in "incorrect order", libc comes before libthr in ldd output. My > debugging shows that fork is resolved from libc, not from libthr. > Not sure what to blame here: > - build toolchain for putting libc before libthr > - rtld for not preferring libthr over libc > - libc/libthr for being split into two pieces in the current way - The build procedure for chromium. libc/[libc_r, libpthread, libthr] have always behaved that way since the libc/libc_r split. -- DE