On Wed, Nov 22, 2023 at 11:45:49AM +0000, Ricardo Ribalda wrote: > usb drivers should not call to any I/O function after the > .disconnect() callback has been triggered. > https://www.kernel.org/doc/html/latest/driver-api/usb/callbacks.html#the-disconnect-callback > > If an application is receiving frames form a camera and the device is > disconnected: the device will call close() after the usb .disconnect() > callback has been called. The streamoff path will call usb_set_interface > or usb_clear_halt, which is not allowed. > > This patch only solves the calls to close() *after* .disconnect() is > being called. > > 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 d5dbf2644272..d78640d422f4 100644 > --- a/drivers/media/usb/uvc/uvc_driver.c > +++ b/drivers/media/usb/uvc/uvc_driver.c > @@ -2266,6 +2266,8 @@ static void uvc_disconnect(struct usb_interface *intf) > return; > > uvc_unregister_video(dev); > + /* Barrier needed to pair with uvc_video_stop_streaming(). */ > + smp_store_release(&dev->disconnected, true); I can't think this would be such a hot path that we really need barriers in the driver. > 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..f5ef375088de 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) { > 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 > + * 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 pair 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 ba8f8c1f2c83..5b1a3643de05 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; > -- Regards, Laurent Pinchart
