[PATCH] drm/virtio: Revert "drm/virtio: Call the right shmem helpers"

[Gerd Hoffmann]

On Mon, Jun 15, 2020 at 04:05:00PM -0700, Gurchetan Singh wrote:
> This reverts commit d323bb44e4d23802eb25d13de1f93f2335bd60d0.
> 
> Fixes a double-free regression:
> 
> [    4.357928]  drm_gem_shmem_free_object+0xb4/0x100
> [    4.358983]  virtio_gpu_dequeue_ctrl_func+0xd9/0x290
> [    4.360343]  process_one_work+0x1d2/0x3a0
> [    4.361581]  worker_thread+0x45/0x3c0
> [    4.362645]  kthread+0xf6/0x130
> [    4.363543]  ? process_one_work+0x3a0/0x3a0
> [    4.364770]  ? kthread_park+0x80/0x80
> [    4.365799]  ret_from_fork+0x35/0x40
> [    4.367103] Modules linked in:
> [    4.367958] CR2: 0000000000000018
> [    4.368857] ---[ end trace db84f7a2974d5c79 ]---
> [    4.370118] RIP: 0010:dma_direct_unmap_sg+0x1f/0x60
> 
> In addition, virtio has it's own set of dma-ops so there's not an
> obviously clean way to transition to shmem helpers.
> 
> Fixes: d323bb44e4d2 ("drm/virtio: Call the right shmem helpers")
> Signed-off-by: Gurchetan Singh <gurchetansingh at chromium.org>

Pushed to drm-misc-next (will cherry-pick into -fixes once that is
rebased to 5.9-rc1 or newer).

thanks,
  Gerd