diff mbox series

[v4,1/4] media: uvcvideo: stop stream during unregister

Message ID 20240327-guenter-mini-v4-1-49955c198eae@chromium.org (mailing list archive)
State New
Headers show
Series uvcvideo: Attempt N to land UVC race conditions fixes | expand

Commit Message

Ricardo Ribalda March 27, 2024, 8:24 a.m. UTC 
uvc_unregister_video() can be called asynchronously from
uvc_disconnect(). If the device is still streaming when that happens, a
plethora of race conditions can happen.

Make sure that the device has stopped streaming before exiting this
function.

If the user still holds handles to the driver's file descriptors, any
ioctl will return -ENODEV from the v4l2 core.

This change make uvc more consistent with the rest of the v4l2 drivers
using the vb2_fop_* and vb2_ioctl_* helpers.

Suggested-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_driver.c | 11 +++++++++++
 1 file changed, 11 insertions(+)
diff mbox series

Patch

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index bbd90123a4e76..17fc945c8deb6 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -1911,8 +1911,19 @@  static void uvc_unregister_video(struct uvc_device *dev)
 		if (!video_is_registered(&stream->vdev))
 			continue;
 
+		/*
+		 * Serialize other access to the stream.
+		 */
+		mutex_lock(&stream->mutex);
+		uvc_queue_streamoff(&stream->queue, stream->type);
 		video_unregister_device(&stream->vdev);
 		video_unregister_device(&stream->meta.vdev);
+		mutex_unlock(&stream->mutex);
+
+		/*
+		 * Now the vdev is not streaming and all the ioctls will
+		 * return -ENODEV
+		 */
 
 		uvc_debugfs_cleanup_stream(stream);
 	}