2 files changed, 54 insertions, 11 deletions

diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
index bebf2415d9de..cd8c03341de0 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/drivers/media/usb/uvc/uvc_queue.c
@@ -142,6 +142,7 @@ static void uvc_buffer_queue(struct vb2_buffer *vb)
 
 	spin_lock_irqsave(&queue->irqlock, flags);
 	if (likely(!(queue->flags & UVC_QUEUE_DISCONNECTED))) {
+		kref_init(&buf->ref);
 		list_add_tail(&buf->queue, &queue->irqqueue);
 	} else {
 		/* If the device is disconnected return the buffer to userspace
@@ -459,28 +460,66 @@ struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue)
 	return nextbuf;
 }
 
-struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
+/*
+ * uvc_queue_buffer_requeue: Requeue a buffer on our internal irqqueue
+ *
+ * Reuse a buffer through our internal queue without the need to 'prepare'.
+ * The buffer will be returned to userspace through the uvc_buffer_queue call if
+ * the device has been disconnected.
+ */
+static void uvc_queue_buffer_requeue(struct uvc_video_queue *queue,
 		struct uvc_buffer *buf)
 {
-	struct uvc_buffer *nextbuf;
-	unsigned long flags;
+	buf->error = 0;
+	buf->state = UVC_BUF_STATE_QUEUED;
+	buf->bytesused = 0;
+	vb2_set_plane_payload(&buf->buf.vb2_buf, 0, 0);
+
+	uvc_buffer_queue(&buf->buf.vb2_buf);
+}
+
+static void uvc_queue_buffer_complete(struct kref *ref)
+{
+	struct uvc_buffer *buf = container_of(ref, struct uvc_buffer, ref);
+	struct vb2_buffer *vb = &buf->buf.vb2_buf;
+	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
 
 	if ((queue->flags & UVC_QUEUE_DROP_CORRUPTED) && buf->error) {
-		buf->error = 0;
-		buf->state = UVC_BUF_STATE_QUEUED;
-		buf->bytesused = 0;
-		vb2_set_plane_payload(&buf->buf.vb2_buf, 0, 0);
-		return buf;
+		uvc_queue_buffer_requeue(queue, buf);
+		return;
 	}
 
+	buf->state = buf->error ? UVC_BUF_STATE_ERROR : UVC_BUF_STATE_DONE;
+	vb2_set_plane_payload(&buf->buf.vb2_buf, 0, buf->bytesused);
+	vb2_buffer_done(&buf->buf.vb2_buf, VB2_BUF_STATE_DONE);
+}
+
+/*
+ * Release a reference on the buffer. Complete the buffer when the last
+ * reference is released.
+ */
+void uvc_queue_buffer_release(struct uvc_buffer *buf)
+{
+	kref_put(&buf->ref, uvc_queue_buffer_complete);
+}
+
+/*
+ * Remove this buffer from the queue. Lifetime will persist while async actions
+ * are still running (if any), and uvc_queue_buffer_release will give the buffer
+ * back to VB2 when all users have completed.
+ */
+struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
+		struct uvc_buffer *buf)
+{
+	struct uvc_buffer *nextbuf;
+	unsigned long flags;
+
 	spin_lock_irqsave(&queue->irqlock, flags);
 	list_del(&buf->queue);
 	nextbuf = __uvc_queue_get_current_buffer(queue);
 	spin_unlock_irqrestore(&queue->irqlock, flags);
 
-	buf->state = buf->error ? UVC_BUF_STATE_ERROR : UVC_BUF_STATE_DONE;
-	vb2_set_plane_payload(&buf->buf.vb2_buf, 0, buf->bytesused);
-	vb2_buffer_done(&buf->buf.vb2_buf, VB2_BUF_STATE_DONE);
+	uvc_queue_buffer_release(buf);
 
 	return nextbuf;
 }
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index f6109a4dde5b..92a17f011bf2 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -413,6 +413,9 @@ struct uvc_buffer {
 	unsigned int bytesused;
 
 	u32 pts;
+
+	/* Asynchronous buffer handling. */
+	struct kref ref;
 };
 
 #define UVC_QUEUE_DISCONNECTED		(1 << 0)
@@ -729,6 +732,7 @@ void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
 struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
 					 struct uvc_buffer *buf);
 struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue);
+void uvc_queue_buffer_release(struct uvc_buffer *buf);
 int uvc_queue_mmap(struct uvc_video_queue *queue,
 		   struct vm_area_struct *vma);
 __poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,