Re: [PATCH v2 1/2] drm/prime: reject DMA-BUF attach when get_sg_table is missing

[Thomas Zimmermann]

Hi

Am 02.03.23 um 16:03 schrieb Thomas Zimmermann:

Hi

Am 02.03.23 um 15:35 schrieb Simon Ser:

drm_gem_map_dma_buf() requires drm_gem_object_funcs.get_sg_table
to be implemented, or else WARNs.

Allow drivers to leave this hook unimplemented to implement purely
local DMA-BUFs (ie, DMA-BUFs which cannot be imported anywhere
else but the device which allocated them). In that case, reject
imports to other devices in drm_gem_map_attach().

v2: new patch

Signed-off-by: Simon Ser <cont...@emersion.fr>
Cc: Daniel Vetter <daniel.vet...@ffwll.ch>
Cc: Thomas Zimmermann <tzimmerm...@suse.de>
Cc: Tian Tao <tiant...@hisilicon.com>
Cc: Maxime Ripard <max...@cerno.tech>
Cc: Christian König <christian.koe...@amd.com>
Cc: Hans de Goede <hdego...@redhat.com>
---
  drivers/gpu/drm/drm_prime.c | 6 +++++-
  1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index f924b8b4ab6b..ab1d21d63a03 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c

- * &drm_gem_object_funcs.get_sg_table.

+ * unimplemented, exports into another device are rejected.
   *
   * For kernel-internal access there's drm_gem_dmabuf_vmap() and
   * drm_gem_dmabuf_vunmap(). Userspace mmap support is provided by
@@ -583,6 +584,9 @@ int drm_gem_map_attach(struct dma_buf *dma_buf,
  {
      struct drm_gem_object *obj = dma_buf->priv;
+    if (!obj->funcs->get_sg_table)
+        return -EOPNOTSUPP;

@@ -544,7 +544,8 @@ int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,    * Optional pinning of buffers is handled at dma-buf attach and detach time in    * drm_gem_map_attach() and drm_gem_map_detach(). Backing storage itself is    * handled by drm_gem_map_dma_buf() and drm_gem_unmap_dma_buf(), which relies on + * &drm_gem_object_funcs.get_sg_table. If &drm_gem_object_funcs.get_sg_table is

-ENOSYS please.

With this changed:

Acked-by: Thomas Zimmermann <tzimmerm...@suse.de>

Best regards
Thomas

+
      return drm_gem_pin(obj);
  }
  EXPORT_SYMBOL(drm_gem_map_attach);

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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