From owner-freebsd-current@FreeBSD.ORG Thu Sep 11 06:02:05 2008 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 749581065677 for ; Thu, 11 Sep 2008 06:02:05 +0000 (UTC) (envelope-from vehemens@verizon.net) Received: from vms173001pub.verizon.net (vms173001pub.verizon.net [206.46.173.1]) by mx1.freebsd.org (Postfix) with ESMTP id 500BD8FC20 for ; Thu, 11 Sep 2008 06:02:05 +0000 (UTC) (envelope-from vehemens@verizon.net) Received: from sam ([71.106.248.65]) by vms173001.mailsrvcs.net (Sun Java System Messaging Server 6.2-6.01 (built Apr 3 2006)) with ESMTPA id <0K70008NGORG8B27@vms173001.mailsrvcs.net>; Thu, 11 Sep 2008 01:02:04 -0500 (CDT) Date: Wed, 10 Sep 2008 23:07:31 -0700 From: vehemens In-reply-to: <200809080950.55528.vehemens@verizon.net> To: Robert Watson Message-id: <200809102307.31209.vehemens@verizon.net> MIME-version: 1.0 Content-type: text/plain; charset=iso-8859-1 Content-transfer-encoding: 7bit Content-disposition: inline References: <200809080202.00664.vehemens@verizon.net> <200809080950.55528.vehemens@verizon.net> User-Agent: KMail/1.9.10 Cc: Kostik Belousov , freebsd-current@freebsd.org Subject: cdefpriv usage (was: bsd versus linux device drivers) X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Sep 2008 06:02:05 -0000 On Monday 08 September 2008 09:50:55 am vehemens wrote: > On Monday 08 September 2008 06:41:53 am Robert Watson wrote: > > On Mon, 8 Sep 2008, vehemens wrote: > > > On Monday 08 September 2008 03:04:15 am Kostik Belousov wrote: > > >> On Mon, Sep 08, 2008 at 02:02:00AM -0700, vehemens wrote: > > >>> In linux drivers, there is a one to one relationship to an open and a > > >>> calling argument structure called struct file. It provides a private > > >>> data pointer that allows the driver to preserve unique state > > >>> information across other calls such as read/write/ioctl/mmap/close > > >>> etc. > > >>> > > >>> For bsd drivers, my understanding there is not an equivalent. As a > > >>> result it is not possible to preserve different state information for > > >>> multiple opens by the same thread of the same device major/minor #'s. > > >>> > > >>> Is this correct, or did i miss something? > > >> > > >> There is devfs_{get,set}_cdevpriv() KPI. Still no manpage, I shall fix > > >> this ASAP. > > > > > > Just started looking at the firewire driver which has clone. It looks > > > like it hooks into the event handler. > > > > > > Don't quite understand it all yet, so I'm going to look forward to that > > > man page. > > > > Many device drivers continue to use the old clone interface, but are > > gradually being converted over. You can look at the definitions and list > > of converted drivers here: > > > > http://fxr.watson.org/fxr/ident?im=bigexcerpts;i=devfs_set_cdevpriv > > > > Looking at some of the converted drivers, I find myself a bit worried by > > the extra error handling: in what situations do we expect that bpfioctl() > > might be called without its cdev-private data? > > Got it now. Looks like the converted drivers are only in current, but the > KPI is in at least 7.x as well. My first impression based on the modified drivers, was that I only needed to add a get to open, and set's to ioctl, mmap, read, write, close etc. Also that the data release would occur after the close call via the function provided to get. Don't have a problem with set, but some or all of the get's fail. I see lot's of error=2 in ioctl, and error=9 in mmap, Going to instrument the code next. Any suggestions would be helpful. On a side note, I had to first upgrade my 7.x system and was wondering if there was a FreeBSD_version number for this feature?