v4l2_release
while (completion_done(&cxdev->v4l2_release))
complete(&cxdev->v4l2_release);
init_completion(&cxdev->v4l2_release);
wait_for_completion(&cxdev->v4l2_release);
wait_for_completion(&cxdev->v4l2_release);
struct completion v4l2_release;
.release = v4l2_release,