Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752582AbaKLJmE (ORCPT ); Wed, 12 Nov 2014 04:42:04 -0500 Received: from mail-la0-f53.google.com ([209.85.215.53]:38869 "EHLO mail-la0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752352AbaKLJlS convert rfc822-to-8bit (ORCPT ); Wed, 12 Nov 2014 04:41:18 -0500 MIME-Version: 1.0 In-Reply-To: References: <1415639805-17477-1-git-send-email-daniel.thompson@linaro.org> <54621D21.2000100@linaro.org> Date: Wed, 12 Nov 2014 10:41:16 +0100 Message-ID: Subject: Re: [PATCH v3.18-rc3] drm: msm: Allow exported dma-bufs to be mapped From: Benjamin Gaignard To: Rob Clark Cc: Daniel Thompson , David Airlie , "dri-devel@lists.freedesktop.org" , Linux Kernel Mailing List , "patches@linaro.org" , linaro-kernel@lists.linaro.org, John Stultz , Sumit Semwal , Daniel Vetter , Maarten Lankhorst Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The same kind of issue has been fixed in v4l2: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/patch/drivers/media/v4l2-core/videobuf2-core.c?id=c1b96a236e94d49d9396d0bbceb5524519c5c66e I'm ok to add a DRM_RDWR flag, just do not remove the code from sti driver until I have been able to test it. Benjamin 2014-11-11 17:26 GMT+01:00 Rob Clark : > On Tue, Nov 11, 2014 at 9:28 AM, Daniel Thompson > wrote: >> On 10/11/14 17:36, Rob Clark wrote: >>> On Mon, Nov 10, 2014 at 12:16 PM, Daniel Thompson >>> wrote: >>>> diff --git a/drivers/gpu/drm/msm/msm_gem_prime.c b/drivers/gpu/drm/msm/msm_gem_prime.c >>>> index ad772fe36115..4e4fa5828d5d 100644 >>>> --- a/drivers/gpu/drm/msm/msm_gem_prime.c >>>> +++ b/drivers/gpu/drm/msm/msm_gem_prime.c >>>> @@ -20,6 +20,14 @@ >>>> >>>> #include >>>> >>>> +struct dma_buf *msm_gem_prime_export(struct drm_device *dev, >>>> + struct drm_gem_object *obj, int flags) >>>> +{ >>>> + /* we want to be able to write in mmapped buffer */ >>>> + flags |= O_RDWR; >>>> + return drm_gem_prime_export(dev, obj, flags); >>>> +} >>>> + >>> >>> seems like this probably should be done more centrally.. and in fact, >>> might be better to have something like this in >>> drm_prime_handle_to_fd_ioctl: >>> >>> /* check flags are valid */ >>> - if (args->flags & ~DRM_CLOEXEC) >>> + if (args->flags & ~(DRM_CLOEXEC | O_RDWR)) >>> return -EINVAL; >>> >>> so exporter can specify whether to allow mmap or not. >> >> That makes sense I'll try this. >> >> Do we need to wrap O_RDWR in the same way we wrap O_CLOEXEC? (I don't >> really understand why DRM_CLOEXEC exists; even the patch description >> from when the symbol was introduced names it O_CLOEXEC). > > I *think* wrapping it w/ DRM_CLOEXEC was mostly just for purposes of > making it clear which flags are appropriate.. probably best to do the > same w/ a DRM_RDWR I guess > > BR, > -R > >> Also the "flags |= O_RDWR" approach is copied from the sti driver. I'll >> share a patch to remove it but that will definitely needs Benjamin's ack >> because it will stop some userspaces working correctly (however I >> suspect that Benjamin may be the only person currently with such a >> userspace and that he can be persuaded not to call it a regression). >> >> >> Daniel. -- Benjamin Gaignard Graphic Working Group Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/