From owner-freebsd-hackers@FreeBSD.ORG Wed Jan 21 13:40:31 2009 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 53DF11065B9A for ; Wed, 21 Jan 2009 13:40:31 +0000 (UTC) (envelope-from avg@icyb.net.ua) Received: from citadel.icyb.net.ua (citadel.icyb.net.ua [212.40.38.140]) by mx1.freebsd.org (Postfix) with ESMTP id CF5128FC25 for ; Wed, 21 Jan 2009 13:40:28 +0000 (UTC) (envelope-from avg@icyb.net.ua) Received: from odyssey.starpoint.kiev.ua (alpha-e.starpoint.kiev.ua [212.40.38.101]) by citadel.icyb.net.ua (8.8.8p3/ICyb-2.3exp) with ESMTP id PAA06186; Wed, 21 Jan 2009 15:40:25 +0200 (EET) (envelope-from avg@icyb.net.ua) Message-ID: <497725C8.4010101@icyb.net.ua> Date: Wed, 21 Jan 2009 15:40:24 +0200 From: Andriy Gapon User-Agent: Thunderbird 2.0.0.18 (X11/20081124) MIME-Version: 1.0 To: Kostik Belousov References: <49770513.8090203@icyb.net.ua> <20090121133520.GK58517@deviant.kiev.zoral.com.ua> In-Reply-To: <20090121133520.GK58517@deviant.kiev.zoral.com.ua> Content-Type: text/plain; charset=KOI8-U Content-Transfer-Encoding: 7bit Cc: freebsd-hackers@freebsd.org Subject: Re: device driver: cdesw questions? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 Jan 2009 13:40:34 -0000 on 21/01/2009 15:35 Kostik Belousov said the following: > On Wed, Jan 21, 2009 at 01:20:51PM +0200, Andriy Gapon wrote: >> Question 1: >> I am writing a driver that would use per-open private data (among other >> features). >> Do I have to use D_TRACKCLOSE flag in this case? > No, the dtr registered with devfs_set_cdevpriv(), is called exactly once > when the last close is performed, or the device is destroyed. Kostik, thanks a lot for the explanation! I am still a little bit confused about the term "last close" - what is it? I.e. I'd like to get an answer to the below question. >> In general I am a little bit confused about when d_close is invoked. >> Supposing D_TRACKCLOSE is not set and multiple programs concurrently >> open, use and close a device - when d_close is called - when one program >> closes its last descriptor tied to the device or when the system-wide >> last such descriptor is closed? -- Andriy Gapon