Hi
Am 15.04.25 um 11:39 schrieb Christian König:
Am 15.04.25 um 11:20 schrieb Thomas Zimmermann:
Test struct drm_gem_object.import_attach to detect imported objects during cleanup. At that point, the imported DMA buffer might have already been released and the dma_buf field is NULL. The object's free callback then does a cleanup as for native objects.
I don't think that this is a good idea.
The DMA-buf is separately reference counted through the import attachment.
I understand that it's not ideal, but testing for import_attach to be set is what we currently do throughout drivers. Putting this behind an interface is already a step forward.
Happens for calls to drm_mode_destroy_dumb_ioctl() that eventually clear the dma_buf field in drm_gem_object_exported_dma_buf_free().
That is for exported DMA-buf and should *NEVER* be used for imported ones.
Did you look at the discussion at the Closes tag? Where else could dma-buf be cleared?
Best regards Thomas
Regards, Christian.
Signed-off-by: Thomas Zimmermann tzimmermann@suse.de Fixes: b57aa47d39e9 ("drm/gem: Test for imported GEM buffers with helper") Reported-by: Andy Yan andyshrk@163.com Closes: https://lore.kernel.org/dri-devel/38d09d34.4354.196379aa560.Coremail.andyshr... Tested-by: Andy Yan andyshrk@163.com Cc: Thomas Zimmermann tzimmermann@suse.de Cc: Anusha Srivatsa asrivats@redhat.com Cc: Christian König christian.koenig@amd.com Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Maxime Ripard mripard@kernel.org Cc: David Airlie airlied@gmail.com Cc: Simona Vetter simona@ffwll.ch Cc: Sumit Semwal sumit.semwal@linaro.org Cc: "Christian König" christian.koenig@amd.com Cc: dri-devel@lists.freedesktop.org Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org
include/drm/drm_gem.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index 9b71f7a9f3f8..f09b8afcf86d 100644 --- a/include/drm/drm_gem.h +++ b/include/drm/drm_gem.h @@ -589,7 +589,13 @@ static inline bool drm_gem_object_is_shared_for_memory_stats(struct drm_gem_obje static inline bool drm_gem_is_imported(const struct drm_gem_object *obj) { /* The dma-buf's priv field points to the original GEM object. */
- return obj->dma_buf && (obj->dma_buf->priv != obj);
- return (obj->dma_buf && (obj->dma_buf->priv != obj)) ||
/** TODO: During object release, the dma-buf might already* be gone. For now keep testing import_attach, but* this should be removed at some point.*/obj->import_attach;#ifdef CONFIG_LOCKDEP