drm: prime: fix refcounting on the dmabuf import error path

In commit be8a42ae60 we inroduced a refcount problem, where on the
drm_gem_prime_fd_to_handle() error path we'll call dma_buf_put() for
self imported dma buffers.

Fix this by taking a reference on the dma buffer in the .gem_import
hook instead of assuming the caller had taken one. Besides fixing the
bug this is also more logical.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Cc: stable@vger.kernel.org
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
index ba0a3aa78547..ff7f2a886a34 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
@@ -235,7 +235,6 @@ struct drm_gem_object *exynos_dmabuf_prime_import(struct drm_device *drm_dev,
                          * refcount on gem itself instead of f_count of dmabuf.
                          */
                         drm_gem_object_reference(obj);
-                        dma_buf_put(dma_buf);
                         return obj;
                 }
         }
@@ -244,6 +243,7 @@ struct drm_gem_object *exynos_dmabuf_prime_import(struct drm_device *drm_dev,
         if (IS_ERR(attach))
                 return ERR_PTR(-EINVAL);
 
+        get_dma_buf(dma_buf);
 
         sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
         if (IS_ERR_OR_NULL(sgt)) {
@@ -298,6 +298,8 @@ err_unmap_attach:
         dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
 err_buf_detach:
         dma_buf_detach(dma_buf, attach);
+        dma_buf_put(dma_buf);
+
         return ERR_PTR(ret);
 }