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, 4 insertions, 0 deletions

diff --git a/drivers/gpu/drm/udl/udl_gem.c b/drivers/gpu/drm/udl/udl_gem.c
index 3816270ba49b..ef034fa3e6f5 100644
--- a/drivers/gpu/drm/udl/udl_gem.c
+++ b/drivers/gpu/drm/udl/udl_gem.c
@@ -303,6 +303,8 @@ struct drm_gem_object *udl_gem_prime_import(struct drm_device *dev,
         if (IS_ERR(attach))
                 return ERR_CAST(attach);
 
+        get_dma_buf(dma_buf);
+
         sg = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
         if (IS_ERR(sg)) {
                 ret = PTR_ERR(sg);
@@ -322,5 +324,7 @@ fail_unmap:
         dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
 fail_detach:
         dma_buf_detach(dma_buf, attach);
+        dma_buf_put(dma_buf);
+
         return ERR_PTR(ret);
 }