From owner-freebsd-hackers@FreeBSD.ORG Wed Jan 21 14:16:17 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 9A2731065B18 for ; Wed, 21 Jan 2009 14:16:17 +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 8392B8FC18 for ; Wed, 21 Jan 2009 14:16:16 +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 QAA07340; Wed, 21 Jan 2009 16:16:13 +0200 (EET) (envelope-from avg@icyb.net.ua) Message-ID: <49772E2C.7050008@icyb.net.ua> Date: Wed, 21 Jan 2009 16:16:12 +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> <49772D47.2090602@icyb.net.ua> <20090121141509.GN58517@deviant.kiev.zoral.com.ua> In-Reply-To: <20090121141509.GN58517@deviant.kiev.zoral.com.ua> Content-Type: text/plain; charset=KOI8-U Content-Transfer-Encoding: 7bit Cc: freebsd-hackers@FreeBSD.org, Robert Watson 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 14:16:18 -0000 on 21/01/2009 16:15 Kostik Belousov said the following: > On Wed, Jan 21, 2009 at 04:12:23PM +0200, Andriy Gapon wrote: >> on 21/01/2009 16:05 Robert Watson said the following: >>> On Wed, 21 Jan 2009, 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? 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? >>> Kostik has already pointed at the cdevpriv API, but just to reiterate >>> his point: most people will find the semantics of D_TRACKCLOSE confusing >>> and consider them incorrect, so I would advise against using them. >> Robert, Kostik, >> >> in simplistic layman's terms I need the following - when a particular >> program "closes my cdev" (explicitly or via exit) I need to catch that >> and de-allocate certain resources. There can be multiple concurrent >> programs opening, using and closing my cdev. >> >> I guess what you both say is that I shouldn't use D_TRACKCLOSE, instead >> I should perform the resource management in cdevpriv destructor. >> Am I guessing correctly this time? > > Yes. This is the purpose of the cdevpriv KPI. Thank you! Sorry for being so thick :-) -- Andriy Gapon