Hi Laurent, Just a reminder: I have extensively reviewed this patch here: https://lore.kernel.org/linux-media/f4c49ccf-9dc9-475a-8fc9-4ef4c85a729a@xxxxxxxxx/ and here (specifically checking for mmap() races): https://lore.kernel.org/linux-media/1a10530f-b4bb-4244-84ff-1f2365ae9b23@xxxxxxxxx/ To the best of my ability I believe this patch is correct. Unless you have any additional concerns I plan to take this patch as a fix for v6.12 on Monday next week. Alternatively, you can make a PR for 6.12 with this patch that I can pull from. Regards, Hans On 26/09/2024 07:59, Ricardo Ribalda wrote: > 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 occur. > > 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 makes uvc more consistent with the rest of the v4l2 drivers > using the vb2_fop_* and vb2_ioctl_* helpers. > > Reviewed-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx> > Suggested-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx> > Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx> > --- > This patch was part of the series: > https://patchwork.linuxtv.org/project/linux-media/list/?series=13064 > > Moved out from it to ease the review. > --- > drivers/media/usb/uvc/uvc_driver.c | 32 +++++++++++++++++++++++++++++++- > 1 file changed, 31 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c > index f0febdc08c2d..bee150b852e4 100644 > --- a/drivers/media/usb/uvc/uvc_driver.c > +++ b/drivers/media/usb/uvc/uvc_driver.c > @@ -1919,11 +1919,41 @@ static void uvc_unregister_video(struct uvc_device *dev) > struct uvc_streaming *stream; > > list_for_each_entry(stream, &dev->streams, list) { > + /* Nothing to do here, continue. */ > 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); > - video_unregister_device(&stream->meta.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->meta.vdev); > + > + /* > + * Now both vdevs are not streaming and all the ioctls will > + * return -ENODEV. > + */ > > uvc_debugfs_cleanup_stream(stream); > } > > --- > base-commit: 81ee62e8d09ee3c7107d11c8bbfd64073ab601ad > change-id: 20240926-uvc_stop_streaming-6e9fd20e97bc > > Best regards,
