dma-buf: add release callback support

Change-Id: Ibfb4ffe3d97fae0a27f20032fdfbc3cc561aa375
Signed-off-by: Mark Yao <mark.yao@rock-chips.com>

drivers/dma-buf/dma-buf.c

@@ -36,6 +36,12 @@
 
 static inline int is_dma_buf_file(struct file *);
 
+struct dma_buf_callback {
+	struct list_head list;
+	void (*callback)(void *);
+	void *data;
+};
+
 struct dma_buf_list {
 	struct list_head head;
 	struct mutex lock;
@@ -46,6 +52,7 @@ static struct dma_buf_list db_list;
 static int dma_buf_release(struct inode *inode, struct file *file)
 {
 	struct dma_buf *dmabuf;
+	struct dma_buf_callback *cb, *tmp;
 
 	if (!is_dma_buf_file(file))
 		return -EINVAL;
@@ -64,6 +71,13 @@ static int dma_buf_release(struct inode *inode, struct file *file)
 	 */
 	BUG_ON(dmabuf->cb_shared.active || dmabuf->cb_excl.active);
 
+	list_for_each_entry_safe(cb, tmp, &dmabuf->release_callbacks, list) {
+		if (cb->callback)
+			cb->callback(cb->data);
+		list_del(&cb->list);
+		kfree(cb);
+	}
+
 	dmabuf->ops->release(dmabuf);
 
 	mutex_lock(&db_list.lock);
@@ -266,6 +280,37 @@ static inline int is_dma_buf_file(struct file *file)
 	return file->f_op == &dma_buf_fops;
 }
 
+int dma_buf_set_release_callback(struct dma_buf *dmabuf,
+				 void (*callback)(void *), void *data)
+{
+	struct dma_buf_callback *cb;
+
+	if (WARN_ON(dma_buf_get_release_callback_data(dmabuf, callback)))
+		return -EINVAL;
+
+	cb = kzalloc(sizeof(*cb), GFP_KERNEL);
+	if (!cb)
+		return -ENOMEM;
+	cb->callback = callback;
+	cb->data = data;
+	list_add_tail(&cb->list, &dmabuf->release_callbacks);
+
+	return 0;
+}
+
+void *dma_buf_get_release_callback_data(struct dma_buf *dmabuf,
+					void (*callback)(void *))
+{
+	struct dma_buf_callback *cb, *tmp;
+
+	list_for_each_entry_safe(cb, tmp, &dmabuf->release_callbacks, list) {
+		if (cb->callback == callback)
+			return cb->data;
+	}
+
+	return NULL;
+}
+
 /**
  * dma_buf_export - Creates a new dma_buf, and associates an anon file
  * with this buffer, so it can be exported.
@@ -341,6 +386,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
 
 	mutex_init(&dmabuf->lock);
 	INIT_LIST_HEAD(&dmabuf->attachments);
+	INIT_LIST_HEAD(&dmabuf->release_callbacks);
 
 	mutex_lock(&db_list.lock);
 	list_add(&dmabuf->list_node, &db_list.head);

include/linux/dma-buf.h

@@ -90,6 +90,9 @@ struct dma_buf_ops {
 	 * if the call would block.
 	 */
 
+	int (*set_release_callback)(void (*release_callback)(void *data),
+				    void *data);
+	void *(*get_release_callback_data)(void *callback);
 	/* after final dma_buf_put() */
 	void (*release)(struct dma_buf *);
 
@@ -125,6 +128,7 @@ struct dma_buf {
 	size_t size;
 	struct file *file;
 	struct list_head attachments;
+	struct list_head release_callbacks;
 	const struct dma_buf_ops *ops;
 	/* mutex to serialize list manipulation, attach/detach and vmap/unmap */
 	struct mutex lock;
@@ -209,6 +213,12 @@ static inline void get_dma_buf(struct dma_buf *dmabuf)
 	get_file(dmabuf->file);
 }
 
+int dma_buf_set_release_callback(struct dma_buf *dmabuf,
+				 void (*callback)(void *), void *data);
+
+void *dma_buf_get_release_callback_data(struct dma_buf *dmabuf,
+					void (*callback)(void *));
+
 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 							struct device *dev);
 void dma_buf_detach(struct dma_buf *dmabuf,