From owner-svn-src-head@FreeBSD.ORG Thu May 21 15:47:02 2009 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 DB603106566C; Thu, 21 May 2009 15:47:02 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from mail.terabit.net.ua (mail.terabit.net.ua [195.137.202.147]) by mx1.freebsd.org (Postfix) with ESMTP id 75A4E8FC17; Thu, 21 May 2009 15:47:02 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from skuns.zoral.com.ua ([91.193.166.194] helo=mail.zoral.com.ua) by mail.terabit.net.ua with esmtps (TLSv1:AES256-SHA:256) (Exim 4.63 (FreeBSD)) (envelope-from ) id 1M7ATz-000F2g-Md; Thu, 21 May 2009 18:46:59 +0300 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 n4LFkSbZ028076 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 21 May 2009 18:46:28 +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 (8.14.3/8.14.3) with ESMTP id n4LFkSAD071946; Thu, 21 May 2009 18:46:28 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.3/8.14.3/Submit) id n4LFkSEl071945; Thu, 21 May 2009 18:46:28 +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: Thu, 21 May 2009 18:46:28 +0300 From: Kostik Belousov To: "M. Warner Losh" Message-ID: <20090521154628.GP1927@deviant.kiev.zoral.com.ua> References: <3bbf2fe10905210629p46c7a204v6863aaba77354462@mail.gmail.com> <200905210942.35555.jhb@freebsd.org> <20090521.094100.70797067.imp@bsdimp.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="ByWDhVrfOLxO82cA" Content-Disposition: inline In-Reply-To: <20090521.094100.70797067.imp@bsdimp.com> User-Agent: Mutt/1.4.2.3i X-Virus-Scanned: clamav-milter 0.95.1 at 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=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on skuns.kiev.zoral.com.ua X-Virus-Scanned: mail.terabit.net.ua 1M7ATz-000F2g-Md ee527a919ce8ab76b3072688dd97ff10 X-Terabit: YES Cc: src-committers@FreeBSD.org, jhb@FreeBSD.org, svn-src-all@FreeBSD.org, attilio@FreeBSD.org, rwatson@FreeBSD.org, svn-src-head@FreeBSD.org Subject: Re: svn commit: r192535 - 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: Thu, 21 May 2009 15:47:03 -0000 --ByWDhVrfOLxO82cA Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, May 21, 2009 at 09:41:00AM -0600, M. Warner Losh wrote: > In message: > Robert Watson writes: > : On Thu, 21 May 2009, John Baldwin wrote: > :=20 > : >>>> Move the M_WAITOK flag in notify() into an M_NOWAIT one in order= to > : > match > : >>>> the behaviour alredy present with the further malloc() call in > : >>>> devctl_notify(). > : >>>> This fixes a bug in the CAM layer where the camisr handler finis= hed to > : >>>> call camperiphfree() (and subsequently destroy_dev() resulting i= n a new > : >>>> dev notify) while the xpt lock is held. > : >>> This is wrong. You cannot call destroy_dev() while holding any mute= x.=20 > : >>> Taking this into account, it makes no sense to use M_NOWAIT in noti= fy(). > : >> > : >> As long as devctl_notify() also calls M_NOWAIT and if not available = skips=20 > : >> "silently" it just does the same thing, I think this approach is mor= e=20 > : >> consistent. > : >> > : >> It remains, though, the fact to fix CAM when calling destroy_dev(). = Maybe=20 > : >> we should add a witness_warn() there? > : > > : > I agree with kib, this should be reverted and CAM fixed instead. I a= lso=20 > : > agree that M_NOWAIT use should be limited where possible. > :=20 > : devctl_notify() probably needs to grow a sleepable flag, or perhaps we = need=20 > : two variations, one that can sleep. >=20 > devctl_notify() has expanded well beyond its original needs. Having > an extra case for sleeping is the wrong way to solve this problem. > Really. We're adding hacks on hacks on hacks here and we need to step > back and think. >=20 > I specifically didn't put in CDEV notifications into devd when I > originally did it because one can get the same notification via > kevents on /dev. Maybe the right answer is to remove this stuff > entirely and update devd to do that instead? It isn't a lot of code, > and should provide equivalent functionality without needing to change > the rules of the game when it comes to destroy_dev(). Especially this > close to the code slush... >=20 There is no need to change anything except backing out Attilio' change. --ByWDhVrfOLxO82cA Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (FreeBSD) iEYEARECAAYFAkoVd1MACgkQC3+MBN1Mb4gACgCg2oB2+00GRFYpZc7dYmzRmWl9 GLgAoNz2IJMEe7dn4aoGmh8SkW5JJ+6B =CkCM -----END PGP SIGNATURE----- --ByWDhVrfOLxO82cA--