From owner-freebsd-stable@FreeBSD.ORG Mon Mar 10 20:02:04 2008 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 3338B106566B; Mon, 10 Mar 2008 20:02:04 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from relay03.kiev.sovam.com (relay03.kiev.sovam.com [62.64.120.201]) by mx1.freebsd.org (Postfix) with ESMTP id BA3548FC16; Mon, 10 Mar 2008 20:02:03 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from [212.82.216.226] (helo=skuns.kiev.zoral.com.ua) by relay03.kiev.sovam.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.67) (envelope-from ) id 1JYoC2-000GqS-1o; Mon, 10 Mar 2008 22:02:02 +0200 Received: from deviant.kiev.zoral.com.ua (root@deviant.kiev.zoral.com.ua [10.1.1.148]) by skuns.kiev.zoral.com.ua (8.14.2/8.14.2) with ESMTP id m2AK24dc074189 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 10 Mar 2008 22:02:05 +0200 (EET) (envelope-from kostikbel@gmail.com) Received: from deviant.kiev.zoral.com.ua (kostik@localhost [127.0.0.1]) by deviant.kiev.zoral.com.ua (8.14.2/8.14.2) with ESMTP id m2AK1oGO009208; Mon, 10 Mar 2008 22:01:50 +0200 (EET) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.2/8.14.2/Submit) id m2AK1oWx009207; Mon, 10 Mar 2008 22:01:50 +0200 (EET) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: deviant.kiev.zoral.com.ua: kostik set sender to kostikbel@gmail.com using -f Date: Mon, 10 Mar 2008 22:01:50 +0200 From: Kostik Belousov To: John Baldwin Message-ID: <20080310200150.GE10374@deviant.kiev.zoral.com.ua> References: <200803080201.51851.window@ttk.ru> <20080308112129.GW57756@deviant.kiev.zoral.com.ua> <200803101512.44835.jhb@freebsd.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="7CZp05NP8/gJM8Cl" Content-Disposition: inline In-Reply-To: <200803101512.44835.jhb@freebsd.org> User-Agent: Mutt/1.4.2.3i X-Virus-Scanned: ClamAV version 0.91.2, clamav-milter version 0.91.2 on skuns.kiev.zoral.com.ua X-Virus-Status: Clean X-Spam-Status: No, score=-4.4 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 autolearn=ham version=3.2.4 X-Spam-Checker-Version: SpamAssassin 3.2.4 (2008-01-01) on skuns.kiev.zoral.com.ua X-Scanner-Signature: f2683d8df775da069012ccac6e6e6321 X-DrWeb-checked: yes X-SpamTest-Envelope-From: kostikbel@gmail.com X-SpamTest-Group-ID: 00000000 X-SpamTest-Header: Not Detected X-SpamTest-Info: Profiles 2374 [Mar 9 2008] X-SpamTest-Info: helo_type=3 X-SpamTest-Method: none X-SpamTest-Rate: 0 X-SpamTest-Status: Not detected X-SpamTest-Status-Extended: not_detected X-SpamTest-Version: SMTP-Filter Version 3.0.0 [0278], KAS30/Release Cc: Oleg Sidorkin , freebsd-stable@freebsd.org Subject: Re: [Panic] Removing of the Palm during select syscall causes panic X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 10 Mar 2008 20:02:04 -0000 --7CZp05NP8/gJM8Cl Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Mar 10, 2008 at 03:12:44PM -0400, John Baldwin wrote: > On Saturday 08 March 2008 06:21:29 am Kostik Belousov wrote: > > On Sat, Mar 08, 2008 at 02:01:51AM +0300, Oleg Sidorkin wrote: > > > Hello, > > >=20 > > > I'm running 7.0-Stable on the ASUS P5K-VM + Intel Q6600 box. > > > If Palm device is disconnected after synchronization, system crashes = with=20 > > > following stacktrace: > > >=20 > > > Does anyone have any ideas? > >=20 > > I posted the patch several days ago, see > > http://lists.freebsd.org/pipermail/freebsd-current/2008-March/084076.ht= ml >=20 > So this axes the Giant trick stuff, is this because there are race with t= he=20 > cdevsw pointer itself? There is a separate race with cdevsw being uninitialized while device is created that is fixed in the patch. The panic reported is caused by the dereference of the cdev->si_devsw in the giant_trick wrappers without holding the dev_mtx. In fact, dropping dev_mtx in dev(vn)_refthreads and then dereferencing the si_devsw. The destroy_devl() routine zeroes out si_devsw before waiting for si_threadcount to settle to zero. This works as a barrier for dev_refthread. Dereferencing si_devsw afterward requires either the same check or returning giant_trick from dev_refthread or axing gianttrick (dev_refthread returns cdevsw). I choose the later. --7CZp05NP8/gJM8Cl Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.8 (FreeBSD) iEYEARECAAYFAkfVk60ACgkQC3+MBN1Mb4jvDgCgpLmsYj0p/lz2KKYrZMATBb+z WdsAoKei8xy0OUaQI8vcYOsWDa7Nvid0 =gtN8 -----END PGP SIGNATURE----- --7CZp05NP8/gJM8Cl--