From owner-svn-src-head@FreeBSD.ORG Mon Jun 13 21:31:55 2011 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 CBDD7106564A; Mon, 13 Jun 2011 21:31:55 +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 42B0D8FC0C; Mon, 13 Jun 2011 21:31:54 +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 p5DLVopn005593 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 14 Jun 2011 00:31:50 +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 p5DLVoot057620; Tue, 14 Jun 2011 00:31:50 +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 p5DLVo1x057619; Tue, 14 Jun 2011 00:31:50 +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: Tue, 14 Jun 2011 00:31:50 +0300 From: Kostik Belousov To: "Justin T. Gibbs" Message-ID: <20110613213150.GC48734@deviant.kiev.zoral.com.ua> References: <201106132121.p5DLL2Fp099153@svn.freebsd.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="KCLJDKHmrU6/EDiO" Content-Disposition: inline In-Reply-To: <201106132121.p5DLL2Fp099153@svn.freebsd.org> 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=-3.3 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00, 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: r223061 - head/sys/kern 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: Mon, 13 Jun 2011 21:31:55 -0000 --KCLJDKHmrU6/EDiO Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jun 13, 2011 at 09:21:02PM +0000, Justin T. Gibbs wrote: > Author: gibbs > Date: Mon Jun 13 21:21:02 2011 > New Revision: 223061 > URL: http://svn.freebsd.org/changeset/base/223061 >=20 > Log: > Fix a couple of race conditions in devstat(9) initialization. > =20 > In devstat_new_entry(), there is no need to initialize the queue > and the mutex in this function. There are ways to do static > initialization on both, so use STAILQ_HEAD_INITIALIZER and > MTX_SYSINIT to initialize the queue and the mutex. > =20 > In devstat_alloc(), use an atomic test and set routine to guard > making our entry in /dev. Using just a plain static variable > creates a race condition on multiprocessor machines. If you > attempt to create a second entry in devfs, the kernel will panic. Devfs returns an error if MAKEDEV_CHECKNAME flag is supplied and attempt is made to create the existing node. The static guard is still useful, since make_dev() call is costly, but you can remove the atomic, since the race should be of limited scope. --KCLJDKHmrU6/EDiO Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (FreeBSD) iEYEARECAAYFAk32gcYACgkQC3+MBN1Mb4j2AwCdG+xcxM5g23Quq4ZSM+zqvkYF BZcAoOWLa7gs2VQMuVGQXU5x3BJwumQF =0ZGG -----END PGP SIGNATURE----- --KCLJDKHmrU6/EDiO--