From owner-freebsd-arch@FreeBSD.ORG Sun May 11 07:51:20 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 8D9591065677 for ; Sun, 11 May 2008 07:51:20 +0000 (UTC) (envelope-from jroberson@jroberson.net) Received: from wf-out-1314.google.com (wf-out-1314.google.com [209.85.200.170]) by mx1.freebsd.org (Postfix) with ESMTP id 6D3CA8FC18 for ; Sun, 11 May 2008 07:51:20 +0000 (UTC) (envelope-from jroberson@jroberson.net) Received: by wf-out-1314.google.com with SMTP id 28so1762779wfa.7 for ; Sun, 11 May 2008 00:51:20 -0700 (PDT) Received: by 10.142.154.20 with SMTP id b20mr2735136wfe.166.1210492279959; Sun, 11 May 2008 00:51:19 -0700 (PDT) Received: from ?10.0.1.199? ( [24.94.72.120]) by mx.google.com with ESMTPS id 30sm14736630wfa.17.2008.05.11.00.51.17 (version=SSLv3 cipher=RC4-MD5); Sun, 11 May 2008 00:51:18 -0700 (PDT) Date: Sat, 10 May 2008 21:53:12 -1000 (HST) From: Jeff Roberson X-X-Sender: jroberson@desktop To: Kostik Belousov In-Reply-To: <20080504171002.GN18958@deviant.kiev.zoral.com.ua> Message-ID: <20080510214812.Y954@desktop> References: <20080504171002.GN18958@deviant.kiev.zoral.com.ua> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed 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: Sun, 11 May 2008 07:51:20 -0000 On Sun, 4 May 2008, Kostik Belousov wrote: > Since the review for the clone-at-open patch (fdclone) posted some time 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 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 other than devices? If not can we make them a union with the DTYPE_VNODE fields to save space? Thanks, Jeff