6.1-stable review patch. If anyone has any objections, please let me know.
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From: Ricardo Ribalda ribalda@chromium.org
commit c9ec6f1736363b2b2bb4e266997389740f628441 upstream.
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.
This driver (and many other usb drivers) always had this problem, but it wasn't possible to easily fix this until the vb2_video_unregister_device() helper was added. So the Fixes tag points to the creation of that helper.
Reviewed-by: Hans Verkuil hverkuil@xs4all.nl Suggested-by: Hans Verkuil hverkuil@xs4all.nl Signed-off-by: Ricardo Ribalda ribalda@chromium.org Reviewed-by: Mauro Carvalho Chehab mchehab+huawei@kernel.org Fixes: f729ef5796d8 ("media: videobuf2-v4l2.c: add vb2_video_unregister_device helper function") Cc: stable@vger.kernel.org # 5.10.x [hverkuil: add note regarding Fixes version] Signed-off-by: Hans Verkuil hverkuil@xs4all.nl Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/media/usb/uvc/uvc_driver.c | 32 +++++++++++++++++++++++++++++++- 1 file changed, 31 insertions(+), 1 deletion(-)
--- a/drivers/media/usb/uvc/uvc_driver.c +++ b/drivers/media/usb/uvc/uvc_driver.c @@ -1886,11 +1886,41 @@ static void uvc_unregister_video(struct 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); }