From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from db3ehsobe004.messaging.microsoft.com ([213.199.154.142]:1679 "EHLO DB3EHSOBE004.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754746Ab1CVKog (ORCPT ); Tue, 22 Mar 2011 06:44:36 -0400 Date: Tue, 22 Mar 2011 11:44:26 +0100 From: "Roedel, Joerg" To: Florian Mickler CC: Andy Walls , "mchehab@infradead.org" , "linux-media@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "js@linuxtv.org" , "tskd2@yahoo.co.jp" , "liplianin@me.by" , "g.marco@freenet.de" , "aet@rasterburn.org" , "pb@linuxtv.org" , "mkrufky@linuxtv.org" , "nick@nick-andrew.net" , "max@veneto.com" , "janne-dvb@grunau.be" , Oliver Neukum , Greg Kroah-Hartman , "Rafael J. Wysocki" , James Bottomley Subject: Re: [PATCH 0/6] get rid of on-stack dma buffers Message-ID: <20110322104426.GA20444@amd.com> References: <1300732426-18958-1-git-send-email-florian@mickler.org> <20110321220315.7545a61a@schatten.dmk.lab> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20110321220315.7545a61a@schatten.dmk.lab> List-ID: Sender: On Mon, Mar 21, 2011 at 05:03:15PM -0400, Florian Mickler wrote: > I guess (not verified), that the dma api takes sufficient precautions > to abort the dma transfer if a timeout happens. So freeing _should_ > not be an issue. (At least, I would expect big fat warnings everywhere > if that were the case) Freeing is very well an issue. All you can expect from the DMA-API is to give you a valid DMA handle for your device. But it can not prevent that a device uses this handle after you returned it. You need to make sure yourself that any pending DMA is canceled before calling kfree(). Joerg -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632