Hi Ricardo,
Thank you for the patch.
On Tue, Nov 21, 2023 at 07:53:49PM +0000, Ricardo Ribalda wrote:
> usb drivers should not call to any usb_() function after the
> .disconnect() callback has been triggered.
>
> If the camera is streaming, the uvc driver will call usb_set_interface or
> usb_clear_halt once the device is being released. Let's fix this issue.
>
> This is probably not the only driver affected with this kind of bug, but
> until there is a better way to do it in the core this is the way to
> solve this issue.
>
> When/if a different mechanism is implemented in the core to solve the
> lifetime of devices we will adopt it in uvc.
>
> Trace:
> [ 1065.389723] drivers/media/usb/uvc/uvc_driver.c:2248 uvc_disconnect enter
> [ 1065.390160] drivers/media/usb/uvc/uvc_driver.c:2264 uvc_disconnect exit
> [ 1065.433956] drivers/media/usb/uvc/uvc_v4l2.c:659 uvc_v4l2_release enter
> [ 1065.433973] drivers/media/usb/uvc/uvc_video.c:2274 uvc_video_stop_streaming enter
> [ 1065.434560] drivers/media/usb/uvc/uvc_video.c:2285 uvc_video_stop_streaming exit
> [ 1065.435154] drivers/media/usb/uvc/uvc_v4l2.c:680 uvc_v4l2_release exit
> [ 1065.435188] drivers/media/usb/uvc/uvc_driver.c:2248 uvc_disconnect enter
>
> Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
> ---
> drivers/media/usb/uvc/uvc_driver.c | 2 ++
> drivers/media/usb/uvc/uvc_video.c | 45 ++++++++++++++++++++++++--------------
> drivers/media/usb/uvc/uvcvideo.h | 2 ++
> 3 files changed, 32 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index 08fcd2ffa727..413c32867617 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -2257,6 +2257,8 @@ static void uvc_disconnect(struct usb_interface *intf)
> return;
>
> uvc_unregister_video(dev);
> + /* Barrier needed to synchronize with uvc_video_stop_streaming(). */
> + smp_store_release(&dev->disconnected, true);
> kref_put(&dev->ref, uvc_delete);
> }
>
> diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
> index 28dde08ec6c5..032b44e45b22 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -2243,28 +2243,39 @@ int uvc_video_start_streaming(struct uvc_streaming *stream)
> return ret;
> }
>
> -void uvc_video_stop_streaming(struct uvc_streaming *stream)
> +static void uvc_video_halt(struct uvc_streaming *stream)
> {
> - uvc_video_stop_transfer(stream, 1);
> + unsigned int epnum;
> + unsigned int pipe;
> + unsigned int dir;
>
> if (stream->intf->num_altsetting > 1) {
Doesn't this imply the device is using isochronous mode?
> usb_set_interface(stream->dev->udev, stream->intfnum, 0);
> - } else {
> - /*
> - * UVC doesn't specify how to inform a bulk-based device
> - * when the video stream is stopped. Windows sends a
> - * CLEAR_FEATURE(HALT) request to the video streaming
> - * bulk endpoint, mimic the same behaviour.
> - */
> - unsigned int epnum = stream->header.bEndpointAddress
> - & USB_ENDPOINT_NUMBER_MASK;
> - unsigned int dir = stream->header.bEndpointAddress
> - & USB_ENDPOINT_DIR_MASK;
> - unsigned int pipe;
> -
> - pipe = usb_sndbulkpipe(stream->dev->udev, epnum) | dir;
> - usb_clear_halt(stream->dev->udev, pipe);
> + return;
> }
>
> + /*
> + * UVC doesn't specify how to inform a bulk-based device
Then this comment doesn't look right. What about the code? This isn't
mentioned in the commit message either.
> + * when the video stream is stopped. Windows sends a
> + * CLEAR_FEATURE(HALT) request to the video streaming
> + * bulk endpoint, mimic the same behaviour.
> + */
> + epnum = stream->header.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK;
> + dir = stream->header.bEndpointAddress & USB_ENDPOINT_DIR_MASK;
> + pipe = usb_sndbulkpipe(stream->dev->udev, epnum) | dir;
> + usb_clear_halt(stream->dev->udev, pipe);
> +}
> +
> +void uvc_video_stop_streaming(struct uvc_streaming *stream)
> +{
> + uvc_video_stop_transfer(stream, 1);
> +
> + /*
> + * Barrier needed to synchronize with uvc_disconnect().
> + * We cannot call usb_* functions on a disconnected USB device.
> + */
> + if (!smp_load_acquire(&stream->dev->disconnected))
> + uvc_video_halt(stream);
> +
> uvc_video_clock_cleanup(stream);
> }
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index 6fb0a78b1b00..4318ce8e31db 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -559,6 +559,8 @@ struct uvc_device {
> unsigned int users;
> atomic_t nmappings;
>
> + bool disconnected;
> +
> /* Video control interface */
> #ifdef CONFIG_MEDIA_CONTROLLER
> struct media_device mdev;
>
--
Kind regards,
Sakari Ailus
