From owner-freebsd-arch@FreeBSD.ORG Mon May 12 10:16:18 2008 Return-Path: Delivered-To: arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 095E41065673 for ; Mon, 12 May 2008 10:16:18 +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 8DDF78FC19 for ; Mon, 12 May 2008 10:16:17 +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 1JvV4p-000C8P-8G for arch@freebsd.org; Mon, 12 May 2008 13:16:15 +0300 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 m4CAGAUr011587 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 12 May 2008 13:16:11 +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 (8.14.2/8.14.2) with ESMTP id m4CAG8Pp098348; Mon, 12 May 2008 13:16:08 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.2/8.14.2/Submit) id m4CAG7Ym098347; Mon, 12 May 2008 13:16:07 +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: Mon, 12 May 2008 13:16:07 +0300 From: Kostik Belousov To: Jeff Roberson Message-ID: <20080512101607.GC18958@deviant.kiev.zoral.com.ua> References: <20080504171002.GN18958@deviant.kiev.zoral.com.ua> <20080510214812.Y954@desktop> <20080511115030.GV18958@deviant.kiev.zoral.com.ua> <20080511115815.GW18958@deviant.kiev.zoral.com.ua> <20080511153926.T954@desktop> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="bneO9ZV9xXj8K50n" Content-Disposition: inline In-Reply-To: <20080511153926.T954@desktop> 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: cdcac4e9833a162831dcdc7415f73b92 X-DrWeb-checked: yes X-SpamTest-Envelope-From: kostikbel@gmail.com X-SpamTest-Group-ID: 00000000 X-SpamTest-Info: Profiles 2801 [May 12 2008] X-SpamTest-Info: helo_type=3 X-SpamTest-Info: {received from trusted relay: not dialup} X-SpamTest-Method: none X-SpamTest-Method: Local Lists X-SpamTest-Rate: 0 X-SpamTest-Status: Not detected X-SpamTest-Status-Extended: not_detected X-SpamTest-Version: SMTP-Filter Version 3.0.0 [0255], KAS30/Release Cc: arch@freebsd.org Subject: Re: Per-open file private data for the cdevs X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 12 May 2008 10:16:18 -0000 --bneO9ZV9xXj8K50n Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, May 11, 2008 at 03:40:14PM -1000, Jeff Roberson wrote: >=20 > On Sun, 11 May 2008, Kostik Belousov wrote: >=20 > >On Sun, May 11, 2008 at 02:50:30PM +0300, Kostik Belousov wrote: > >>On Sat, May 10, 2008 at 09:53:12PM -1000, Jeff Roberson wrote: > >>>On Sun, 4 May 2008, Kostik Belousov wrote: > >>> > >>>>Since the review for the clone-at-open patch (fdclone) posted some ti= me=20 > >>>>ago > >>>>mostly says that it would be better to implement per-file private data > >>>>instead, I produced the patch along this line, > >>>> > >>>>The patch does not change the cdevsw ABI, instead, three new functions > >>>>nt devfs_get_cdevpriv(void **datap); > >>>>int devfs_set_cdevpriv(void *priv, cdevpriv_dtr_t dtr); > >>>>void devfs_clear_cdevpriv(void); > >>>>are provided for manipulation of the per-file private data. > >>>> > >>>>devfs_set_cdevpriv assigns the priv as private data for the file=20 > >>>>descriptor > >>>>which is used to initiate currently performed driver operation. dtr > >>>>is the function that will be called when either the last refernce to > >>>>the file goes away or devfs_clear_cdevpriv is called. > >>>> > >>>>devfs_get_cdevpriv is the obvious accessor. > >>>> > >>>>devfs_clear_cdevpriv allows to clear the private data for the still > >>>>open file. > >>>> > >>>>The synchronization of the cdev data and file private data is left > >>>>to the driver code, I did not found any generic helper mechanism that > >>>>could be useful there. > >>>> > >>>>Patch: > >>>>http://people.freebsd.org/~kib/misc/fdpriv.1.patch > >>>> > >>>>Dumb driver that shows the basic usage of the proposed KPI: > >>>>http://people.freebsd.org/~kib/misc/fpclone.c > >>>> > >>>>Previous version of the patch was tested by Peter Holm. > >>>> > >>> > >>>Hi Kostik, > >>> > >>>Are these per-instances structures intended to be used by anything oth= er > >>>than devices? If not can we make them a union with the DTYPE_VNODE > >>>fields to save space? > >>> > >>>Thanks, > >>>Jeff > >> > >>The current version of the patch is at > >>http://people.freebsd.org/~kib/misc/fdpriv.3.patch > >> > >>Per insistence of John Baldwin and request of Eric Anholt, the destruct= ors > >>are called now when either file is last closed, or the device is=20 > >>destroyed. > >>This versions adds only one pointer to the struct file. > >> > >>Jeff, would you, please, explicitely specify what field you propose to > >>union with the f_cdevpriv ? >=20 > f_nextoff and f_seqcount are only used if vn_read() and vn_write() are=20 > used. They do not apply to any other descriptors. I use the f_cdevpriv !=3D NULL as an indicator for the necessity to enter the cdevpriv code, in particular, locking the cdevpriv_mtx, that would otherwise needed to be entered at each last close. I think that one pointer for the struct file is not too big cost, do you agree ? >=20 > > > >Of course, I forgot to answer the question. Yes, the KPI is supposed to > >be used by the drivers only. Please, note that device open files have > >DTYPE_VNODE. > > --bneO9ZV9xXj8K50n Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (FreeBSD) iEYEARECAAYFAkgoGOcACgkQC3+MBN1Mb4iVlgCgv214NkFsa0JOpgyYvoY0mMEW vlMAoNpMa/7hrTIR8QQaTWaGfvKhhhht =Ypph -----END PGP SIGNATURE----- --bneO9ZV9xXj8K50n--