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From: Daniel Vetter <daniel@ffwll.ch>
To: "Christian König" <ckoenig.leichtzumerken@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	"moderated list:DMA BUFFER SHARING FRAMEWORK" 
	<linaro-mm-sig@lists.linaro.org>, Linux MM <linux-mm@kvack.org>,
	"open list:DMA BUFFER SHARING FRAMEWORK" 
	<linux-media@vger.kernel.org>
Subject: Re: [PATCH 1/2] drm/shmem-helpers: revert "Redirect mmap for imported dma-buf"
Date: Tue, 15 Sep 2020 12:39:39 +0200	[thread overview]
Message-ID: <CAKMK7uHnZgCBUBQ-5D7gCj1v3Z4wKkeO91tefAoJE1B49JFtww@mail.gmail.com> (raw)
In-Reply-To: <20200914132920.59183-2-christian.koenig@amd.com>

On Mon, Sep 14, 2020 at 3:29 PM Christian König
<ckoenig.leichtzumerken@gmail.com> wrote:
>
> This reverts commit 26d3ac3cb04d171a861952e89324e347598a347f.
>
> We need to figure out if dma_buf_mmap() is valid or not first.
>
> Signed-off-by: Christian König <christian.koenig@amd.com>

The trouble is that doing dma-buf mmap by looking at the struct pages
behind the sg list and just inserting those into userspace doesn't
really work any better. You still won't get the unmap_mapping_range
and hence pte shoot-down. So maybe dma_buf_mmap forwarding doesn't
work, but this doesn't make it any better.

Also commit message should probably explain a bit the context here,
not a lot of people have been in our private discussion on this.
-Daniel

> ---
>  drivers/gpu/drm/drm_gem_shmem_helper.c | 3 ---
>  1 file changed, 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
> index 0a952f27c184..cd727343f72b 100644
> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> @@ -594,9 +594,6 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
>         /* Remove the fake offset */
>         vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node);
>
> -       if (obj->import_attach)
> -               return dma_buf_mmap(obj->dma_buf, vma, 0);
> -
>         shmem = to_drm_gem_shmem_obj(obj);
>
>         ret = drm_gem_shmem_get_pages(shmem);
> --
> 2.17.1
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel



-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

  reply	other threads:[~2020-09-15 10:40 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-14 13:29 Changing vma->vm_file in dma_buf_mmap() Christian König
2020-09-14 13:29 ` [PATCH 1/2] drm/shmem-helpers: revert "Redirect mmap for imported dma-buf" Christian König
2020-09-15 10:39   ` Daniel Vetter [this message]
2020-09-15 11:03     ` Christian König
2020-09-15 11:07       ` Daniel Vetter
2020-09-14 13:29 ` [PATCH 2/2] mm: introduce vma_set_file function Christian König
2020-09-15  9:19   ` kernel test robot
2020-09-15 11:57   ` kernel test robot
2020-09-14 13:30 ` Changing vma->vm_file in dma_buf_mmap() Christian König
2020-09-14 14:06   ` Jason Gunthorpe
2020-09-14 18:26     ` Christian König
2020-09-16  9:53       ` Daniel Vetter
     [not found]         ` <fc8f2af7-9fc2-cb55-3065-75a4060b7c82@amd.com>
     [not found]           ` <b621db68-30b9-cc3f-c2c0-237a7fe4db09@amd.com>
2020-09-16 12:41             ` Daniel Vetter
2020-09-16 14:07         ` Jason Gunthorpe
2020-09-16 14:14           ` Christian König
2020-09-16 15:24             ` Daniel Vetter
2020-09-16 15:31               ` [Linaro-mm-sig] " Christian König
2020-09-17  6:23                 ` Daniel Vetter
2020-09-17  7:11                   ` Christian König
2020-09-17  8:09                     ` Daniel Vetter
2020-09-17 11:31                       ` Jason Gunthorpe
2020-09-17 12:03                         ` Christian König
2020-09-17 12:18                           ` Jason Gunthorpe
2020-09-17 12:24                             ` Christian König
2020-09-17 12:26                               ` Daniel Vetter
2020-09-17 14:35                               ` Jason Gunthorpe
2020-09-17 14:54                                 ` Christian König
2020-09-17 15:24                                   ` Jason Gunthorpe
2020-09-17 15:37                                     ` Daniel Vetter
2020-09-17 16:06                                       ` Christian König
2020-09-17 16:39                                         ` Jason Gunthorpe
2020-09-17 17:23                                           ` Daniel Vetter

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