+
+ /*
+ * btv is protected by btv->lock mutex, while btv->init and other
+ * streaming vars are protected by fh->cap.vb_lock. We need to take
+ * care of both locks to avoid troubles. However, vb_lock is used also
+ * inside videobuf, without calling buf->lock. So, it is a very bad
+ * idea to hold both locks at the same time.
+ * Let's first copy btv->init at fh, holding cap.vb_lock, and then work
+ * with the rest of init, holding btv->lock.
+ */
+ mutex_lock(&fh->cap.vb_lock);