media: uvcvideo: Use vb2 ioctl and fop helpers

When uvc was written the vb2 ioctl and file operation helpers didn't exist.

This patch switches uvc over to those helpers, which removes a lot of
boilerplate code and allows us to drop the 'privileges' scheme, since
that's now handled inside the vb2 helpers.

This makes it possible for uvc to fix the v4l2-compliance streaming tests:
 warn: v4l2-test-formats.cpp(1075): Could not set fmt2

This patch introduces a change on behavior on the uvcdriver to be
aligned with the rest of the subsystem. Now S_INPUT, S_PARM and
S_FORMAT do no grant exclusive ownership of the device.

There are other side effects, some better than others:
- Locking is now more coarse than before, the queue is locked for almost
  every ioctl.
- vidioc_querybuf() can now work when the queue is busy.

Future patches should look into the locking architecture of UVC to
remove one of stream->mutex or queue->mutex.

Reviewed-by: Hans de Goede <hansg@kernel.org>
Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
Co-developed-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Link: https://lore.kernel.org/r/20250616-uvc-fop-v4-1-250286570ee7@chromium.org
Signed-off-by: Hans de Goede <hansg@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>

Author: hverkuil

drivers/media/usb/uvc/uvc_driver.c

@@ -1961,31 +1961,7 @@ static void uvc_unregister_video(struct uvc_device *dev)
 		if (!video_is_registered(&stream->vdev))
 			continue;
 
-		/*
-		 * For stream->vdev we follow the same logic as:
-		 * vb2_video_unregister_device().
-		 */
-
-		/* 1. Take a reference to vdev */
-		get_device(&stream->vdev.dev);
-
-		/* 2. Ensure that no new ioctls can be called. */
-		video_unregister_device(&stream->vdev);
-
-		/* 3. Wait for old ioctls to finish. */
-		mutex_lock(&stream->mutex);
-
-		/* 4. Stop streaming. */
-		uvc_queue_release(&stream->queue);
-
-		mutex_unlock(&stream->mutex);
-
-		put_device(&stream->vdev.dev);
-
-		/*
-		 * For stream->meta.vdev we can directly call:
-		 * vb2_video_unregister_device().
-		 */
+		vb2_video_unregister_device(&stream->vdev);
 		vb2_video_unregister_device(&stream->meta.vdev);
 
 		/*
@@ -2033,6 +2009,8 @@ int uvc_register_video_device(struct uvc_device *dev,
 	vdev->ioctl_ops = ioctl_ops;
 	vdev->release = uvc_release;
 	vdev->prio = &stream->chain->prio;
+	vdev->queue = &queue->queue;
+	vdev->lock = &queue->mutex;
 	if (type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
 		vdev->vfl_dir = VFL_DIR_TX;
 	else
@@ -2397,9 +2375,12 @@ static int __uvc_resume(struct usb_interface *intf, int reset)
 	list_for_each_entry(stream, &dev->streams, list) {
 		if (stream->intf == intf) {
 			ret = uvc_video_resume(stream, reset);
-			if (ret < 0)
-				uvc_queue_streamoff(&stream->queue,
-						    stream->queue.queue.type);
+			if (ret < 0) {
+				mutex_lock(&stream->queue.mutex);
+				vb2_streamoff(&stream->queue.queue,
+					      stream->queue.queue.type);
+				mutex_unlock(&stream->queue.mutex);
+			}
 			return ret;
 		}
 	}

drivers/media/usb/uvc/uvc_metadata.c

@@ -96,7 +96,7 @@ static int uvc_meta_v4l2_set_format(struct file *file, void *fh,
 	 */
 	mutex_lock(&stream->mutex);
 
-	if (uvc_queue_allocated(&stream->queue))
+	if (vb2_is_busy(&stream->meta.queue.queue))
 		ret = -EBUSY;
 	else
 		stream->meta.format = fmt->dataformat;
@@ -164,12 +164,6 @@ int uvc_meta_register(struct uvc_streaming *stream)
 
 	stream->meta.format = V4L2_META_FMT_UVC;
 
-	/*
-	 * The video interface queue uses manual locking and thus does not set
-	 * the queue pointer. Set it manually here.
-	 */
-	vdev->queue = &queue->queue;
-
 	return uvc_register_video_device(dev, stream, vdev, queue,
 					 V4L2_BUF_TYPE_META_CAPTURE,
 					 &uvc_meta_fops, &uvc_meta_ioctl_ops);

drivers/media/usb/uvc/uvc_queue.c

@@ -242,153 +242,10 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
 	return 0;
 }
 
-void uvc_queue_release(struct uvc_video_queue *queue)
-{
-	mutex_lock(&queue->mutex);
-	vb2_queue_release(&queue->queue);
-	mutex_unlock(&queue->mutex);
-}
-
-/* -----------------------------------------------------------------------------
- * V4L2 queue operations
- */
-
-int uvc_request_buffers(struct uvc_video_queue *queue,
-			struct v4l2_requestbuffers *rb)
-{
-	int ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_reqbufs(&queue->queue, rb);
-	mutex_unlock(&queue->mutex);
-
-	return ret ? ret : rb->count;
-}
-
-int uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
-{
-	int ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_querybuf(&queue->queue, buf);
-	mutex_unlock(&queue->mutex);
-
-	return ret;
-}
-
-int uvc_create_buffers(struct uvc_video_queue *queue,
-		       struct v4l2_create_buffers *cb)
-{
-	int ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_create_bufs(&queue->queue, cb);
-	mutex_unlock(&queue->mutex);
-
-	return ret;
-}
-
-int uvc_queue_buffer(struct uvc_video_queue *queue,
-		     struct media_device *mdev, struct v4l2_buffer *buf)
-{
-	int ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_qbuf(&queue->queue, mdev, buf);
-	mutex_unlock(&queue->mutex);
-
-	return ret;
-}
-
-int uvc_export_buffer(struct uvc_video_queue *queue,
-		      struct v4l2_exportbuffer *exp)
-{
-	int ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_expbuf(&queue->queue, exp);
-	mutex_unlock(&queue->mutex);
-
-	return ret;
-}
-
-int uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
-		       int nonblocking)
-{
-	int ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
-	mutex_unlock(&queue->mutex);
-
-	return ret;
-}
-
-int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type)
-{
-	int ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_streamon(&queue->queue, type);
-	mutex_unlock(&queue->mutex);
-
-	return ret;
-}
-
-int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type)
-{
-	int ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_streamoff(&queue->queue, type);
-	mutex_unlock(&queue->mutex);
-
-	return ret;
-}
-
-int uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
-{
-	return vb2_mmap(&queue->queue, vma);
-}
-
-#ifndef CONFIG_MMU
-unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
-		unsigned long pgoff)
-{
-	return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
-}
-#endif
-
-__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
-			    poll_table *wait)
-{
-	__poll_t ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_poll(&queue->queue, file, wait);
-	mutex_unlock(&queue->mutex);
-
-	return ret;
-}
-
 /* -----------------------------------------------------------------------------
  *
  */
 
-/*
- * Check if buffers have been allocated.
- */
-int uvc_queue_allocated(struct uvc_video_queue *queue)
-{
-	int allocated;
-
-	mutex_lock(&queue->mutex);
-	allocated = vb2_is_busy(&queue->queue);
-	mutex_unlock(&queue->mutex);
-
-	return allocated;
-}
-
 /*
  * Cancel the video buffers queue.
  *