From owner-freebsd-current@FreeBSD.ORG Tue Aug 28 16:40:49 2012 Return-Path: Delivered-To: current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 0602A106568C; Tue, 28 Aug 2012 16:40:49 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from bigwig.baldwin.cx (bigknife-pt.tunnel.tserv9.chi1.ipv6.he.net [IPv6:2001:470:1f10:75::2]) by mx1.freebsd.org (Postfix) with ESMTP id CB68A8FC1F; Tue, 28 Aug 2012 16:40:48 +0000 (UTC) Received: from jhbbsd.localnet (unknown [209.249.190.124]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id 26A4BB9A4; Tue, 28 Aug 2012 12:40:48 -0400 (EDT) From: John Baldwin To: Luigi Rizzo Date: Tue, 28 Aug 2012 12:40:29 -0400 User-Agent: KMail/1.13.5 (FreeBSD/8.2-CBSD-20110714-p17; KDE/4.5.5; amd64; ; ) References: <20120827073403.GA49223@onelab2.iet.unipi.it> <201208271227.54785.jhb@freebsd.org> <20120828155025.GA66068@onelab2.iet.unipi.it> In-Reply-To: <20120828155025.GA66068@onelab2.iet.unipi.it> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201208281240.29612.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7 (bigwig.baldwin.cx); Tue, 28 Aug 2012 12:40:48 -0400 (EDT) Cc: freebsd-current@freebsd.org, current@freebsd.org, Andriy Gapon Subject: Re: per file descriptor device callbacks ? 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: Tue, 28 Aug 2012 16:40:49 -0000 On Tuesday, August 28, 2012 11:50:25 am Luigi Rizzo wrote: > On Mon, Aug 27, 2012 at 12:27:54PM -0400, John Baldwin wrote: > > On Monday, August 27, 2012 3:55:47 am Andriy Gapon wrote: > > > on 27/08/2012 10:34 Luigi Rizzo said the following: > > > > This requires to track calls to open/ioctl/poll/mmap/close. > > > > The difficulty i have is with mmap() and close(), because FreeBSD > > > > seems to handle these calls per-cdev rather than per-file-descriptor > > > > (for instance, no 'struct file' argument is available in mmap(), and > > > > the d_close method is only called on the last close() on the device). > > > > > > devfs_set_cdevpriv(9), etc > > > > mmap() is still problematic, but if you have the freedom to create your > > own VM objects, then d_mmap_single() can let you handle that fairly > > easily. > > Would dev_clone(9) be a better way to do what i need ? > > This way the struct cdev would be unique per file descriptor, > could be used as a key on the page fault callbacks > (i still do not have callbacks on dev_pager_ctor/dtor though). dev_clone() is rather gross and a lot harder to use than devfs_set_cdevpriv(). If you are fine with the inherent problems of the device pager (you can't ever make mappings go away), you can just assign each client a unique offset into your shared object's memory space. However, if you are exporting shared memory buffers, then a better model might be to let your clients use shm_open(SHM_ANON) to create buffers, then pass them into your driver via an ioctl() and use shm_map() to map them into the kernel. -- John Baldwin