[PATCH v2 1/2] drm/vmwgfx: Use get_file_active() for dmabuf->file

[Matt Evans]

4ab59c3c638c6 ("dma-buf: Move dma_buf_release() from fops to
dentry_ops") moved the dmabuf .release, and broke the vmwgfx driver's
assumption that dmabuf->file would remain valid until release.
Currently, dmabuf->file can be stale after the file closes even if
.release has not yet been called, and a future commit makes
dmabuf->file become NULL instead of stale.

In preparation for that future commit, convert
get_dma_buf_unless_doomed() to use get_file_active(&dmabuf->file)
which is the safe method to access and get a reference, even when
dmabuf->file could be NULL.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 4ab59c3c638c6 ("dma-buf: Move dma_buf_release() from fops to dentry_ops")
Signed-off-by: Matt Evans <matt@xxxxxxxxxx>
---
 drivers/gpu/drm/vmwgfx/ttm_object.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vmwgfx/ttm_object.c b/drivers/gpu/drm/vmwgfx/ttm_object.c
index f9042bafdc93..9137a31eaa1a 100644
--- a/drivers/gpu/drm/vmwgfx/ttm_object.c
+++ b/drivers/gpu/drm/vmwgfx/ttm_object.c
@@ -471,7 +471,7 @@ void ttm_object_device_release(struct ttm_object_device **p_tdev)
  */
 static bool __must_check get_dma_buf_unless_doomed(struct dma_buf *dmabuf)
 {
-	return file_ref_get(&dmabuf->file->f_ref);
+	return get_file_active(&dmabuf->file) != NULL;
 }
 
 /**
-- 
2.47.3