[PATCH] drm/cma-helper: Fix drm_gem_cma_free_object()

[Daniel Vetter]

On Fri, Apr 26, 2019 at 2:48 PM Noralf Trønnes <noralf at tronnes.org> wrote:
>
> The logic for freeing an imported buffer with a virtual address is
> broken. It will free the buffer instead of unmapping the dma buf.
> Fix by reversing the if ladder and first check if the buffer is imported.
>
> Fixes: b9068cde51ee ("drm/cma-helper: Add DRM_GEM_CMA_VMAP_DRIVER_OPS")
> Cc: stable at vger.kernel.org
> Reported-by: "Li, Tingqian" <tingqian.li at intel.com>
> Signed-off-by: Noralf Trønnes <noralf at tronnes.org>
> ---
>
> This bug is present in 5.0 and it only affects tinydrm drivers that import
> buffers, which is rare if anyone at all is doing it. I'll apply this to
> drm-misc-next and let it trickle down through stable unless someone thinks
> otherwise.

I'd stuff it into drm-misc-next-fixes, since drm-misc-next is for 5.3
which is a bit much of a delay for something tagged cc: stable.
-Daniel

>
> Noralf.
>
>  drivers/gpu/drm/drm_gem_cma_helper.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
> index cc26625b4b33..e01ceed09e67 100644
> --- a/drivers/gpu/drm/drm_gem_cma_helper.c
> +++ b/drivers/gpu/drm/drm_gem_cma_helper.c
> @@ -186,13 +186,13 @@ void drm_gem_cma_free_object(struct drm_gem_object *gem_obj)
>
>         cma_obj = to_drm_gem_cma_obj(gem_obj);
>
> -       if (cma_obj->vaddr) {
> -               dma_free_wc(gem_obj->dev->dev, cma_obj->base.size,
> -                           cma_obj->vaddr, cma_obj->paddr);
> -       } else if (gem_obj->import_attach) {
> +       if (gem_obj->import_attach) {
>                 if (cma_obj->vaddr)
>                         dma_buf_vunmap(gem_obj->import_attach->dmabuf, cma_obj->vaddr);
>                 drm_prime_gem_destroy(gem_obj, cma_obj->sgt);
> +       } else if (cma_obj->vaddr) {
> +               dma_free_wc(gem_obj->dev->dev, cma_obj->base.size,
> +                           cma_obj->vaddr, cma_obj->paddr);
>         }
>
>         drm_gem_object_release(gem_obj);
> --
> 2.20.1
>
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch