From owner-svn-src-head@FreeBSD.ORG Sun Sep 12 20:53:15 2010 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id C9B021065670; Sun, 12 Sep 2010 20:53:15 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from mail.zoral.com.ua (mx0.zoral.com.ua [91.193.166.200]) by mx1.freebsd.org (Postfix) with ESMTP id 3C1D08FC13; Sun, 12 Sep 2010 20:53:14 +0000 (UTC) Received: from deviant.kiev.zoral.com.ua (root@deviant.kiev.zoral.com.ua [10.1.1.148]) by mail.zoral.com.ua (8.14.2/8.14.2) with ESMTP id o8CKrB0R013329 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sun, 12 Sep 2010 23:53:11 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: from deviant.kiev.zoral.com.ua (kostik@localhost [127.0.0.1]) by deviant.kiev.zoral.com.ua (8.14.4/8.14.4) with ESMTP id o8CKrBmQ010695; Sun, 12 Sep 2010 23:53:11 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.4/8.14.4/Submit) id o8CKrBcE010694; Sun, 12 Sep 2010 23:53:11 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: deviant.kiev.zoral.com.ua: kostik set sender to kostikbel@gmail.com using -f Date: Sun, 12 Sep 2010 23:53:11 +0300 From: Kostik Belousov To: Robert Watson Message-ID: <20100912205311.GG2465@deviant.kiev.zoral.com.ua> References: <201009121906.o8CJ68vQ002600@svn.freebsd.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="lqtP4FxvQo6hb6bg" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.3i X-Virus-Scanned: clamav-milter 0.95.2 at skuns.kiev.zoral.com.ua X-Virus-Status: Clean X-Spam-Status: No, score=-2.1 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_50, DNS_FROM_OPENWHOIS autolearn=no version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on skuns.kiev.zoral.com.ua Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r212506 - head/sys/nfsclient X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 12 Sep 2010 20:53:15 -0000 --lqtP4FxvQo6hb6bg Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Sep 12, 2010 at 09:41:46PM +0100, Robert Watson wrote: >=20 > On Sun, 12 Sep 2010, Konstantin Belousov wrote: >=20 > > Do not fork nfsiod directly from the vop methods. This causes LORs betw= een > > vnode lock and several locks needed during fork, like fd lock. > > > > Instead, schedule the task to be executed in the taskqueue context. We > > still waiting for the fork to finish, but the context of the thread > > executing the task does not make real LORs with our vnode lock. >=20 > Does this actually functionally improve things, or is all this complexity= =20 > about suppressing the lock order reversal? If we're waiting synchronousl= y=20 > for the other thread to launch from the task queue, then the lock order= =20 > reversal still exists, it's just not visible to WITNESS... If we had a= =20 > static analysis tool that could run on lock and sleep/wakeup traces, it= =20 > would still show a deadlock opportunity. As I said in commit message, the deadlock should be fixed, because the taskq thread is executed in the kernel process that should even not have file descriptors at all. --lqtP4FxvQo6hb6bg Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (FreeBSD) iEYEARECAAYFAkyNPbYACgkQC3+MBN1Mb4horACdEfBPBECx7PKyITCdgySMJXtg i+8AoMowsZKPz3IJIAjmZin4Ba6dD3YN =Qiid -----END PGP SIGNATURE----- --lqtP4FxvQo6hb6bg--