From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754855Ab1LIWvM (ORCPT ); Fri, 9 Dec 2011 17:51:12 -0500 Received: from hqemgate03.nvidia.com ([216.228.121.140]:4827 "EHLO hqemgate03.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751752Ab1LIWvK (ORCPT ); Fri, 9 Dec 2011 17:51:10 -0500 X-PGP-Universal: processed; by hqnvupgp05.nvidia.com on Fri, 09 Dec 2011 14:50:56 -0800 Date: Fri, 9 Dec 2011 14:50:56 -0800 From: Robert Morell To: Arnd Bergmann Cc: Sumit Semwal , "linux@arm.linux.org.uk" , "jesse.barker@linaro.org" , "linux-kernel@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , "linaro-mm-sig@lists.linaro.org" , "linux-mm@kvack.org" , "daniel@ffwll.ch" , "linux-arm-kernel@lists.infradead.org" , "linux-media@vger.kernel.org" Subject: Re: [Linaro-mm-sig] [RFC v2 1/2] dma-buf: Introduce dma buffer sharing mechanism Message-ID: <20111209225056.GL7969@morell.nvidia.com> References: <1322816252-19955-1-git-send-email-sumit.semwal@ti.com> <1322816252-19955-2-git-send-email-sumit.semwal@ti.com> <201112051718.48324.arnd@arndb.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201112051718.48324.arnd@arndb.de> X-NVConfidentiality: public User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 05, 2011 at 09:18:48AM -0800, Arnd Bergmann wrote: > On Friday 02 December 2011, Sumit Semwal wrote: > > This is the first step in defining a dma buffer sharing mechanism. > [...] > > > + return dmabuf; > > +} > > +EXPORT_SYMBOL(dma_buf_export); > > I agree with Konrad, this should definitely be EXPORT_SYMBOL_GPL, > because it's really a low-level function that I would expect > to get used by in-kernel subsystems providing the feature to > users and having back-end drivers, but it's not the kind of thing > we want out-of-tree drivers to mess with. Is this really necessary? If this is intended to be a lowest-common-denominator between many drivers to allow buffer sharing, it seems like it needs to be able to be usable by all drivers. If the interface is not accessible then I fear many drivers will be forced to continue to roll their own buffer sharing mechanisms (which is exactly what we're trying to avoid here, needless to say). - Robert