dma-buf: replace dma_buf_export() with dma_buf_export_named()

For debugging purposes, it is useful to have a name-string added
while exporting buffers. Hence, dma_buf_export() is replaced with
dma_buf_export_named(), which additionally takes 'exp_name' as a
parameter.

For backward compatibility, and for lazy exporters who don't wish to
name themselves, a #define dma_buf_export() is also made available,
which adds a __FILE__ instead of 'exp_name'.

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
  [Thanks for the idea!]
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>

include/linux/dma-buf.h

@@ -112,6 +112,7 @@ struct dma_buf_ops {
  * @file: file pointer used for sharing buffers across, and for refcounting.
  * @attachments: list of dma_buf_attachment that denotes all devices attached.
  * @ops: dma_buf_ops associated with this buffer object.
+ * @exp_name: name of the exporter; useful for debugging.
  * @priv: exporter specific private data for this buffer object.
  */
 struct dma_buf {
@@ -123,6 +124,7 @@ struct dma_buf {
 	struct mutex lock;
 	unsigned vmapping_counter;
 	void *vmap_ptr;
+	const char *exp_name;
 	void *priv;
 };
 
@@ -162,8 +164,13 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 							struct device *dev);
 void dma_buf_detach(struct dma_buf *dmabuf,
 				struct dma_buf_attachment *dmabuf_attach);
-struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
-			       size_t size, int flags);
+
+struct dma_buf *dma_buf_export_named(void *priv, const struct dma_buf_ops *ops,
+			       size_t size, int flags, const char *);
+
+#define dma_buf_export(priv, ops, size, flags)	\
+	dma_buf_export_named(priv, ops, size, flags, __FILE__)
+
 int dma_buf_fd(struct dma_buf *dmabuf, int flags);
 struct dma_buf *dma_buf_get(int fd);
 void dma_buf_put(struct dma_buf *dmabuf);