static int vin_close(struct file *file)
{
	struct vin_core *vinc = video_drvdata(file);
	struct vin_md *vind = dev_get_drvdata(vinc->v4l2_dev->dev);
	struct vin_vid_cap *cap = &vinc->vid_cap;
	struct modules_config *module = &vind->modules[vinc->sensor_sel];
	int valid_idx = module->sensors.valid_idx;
	int ret;

	if (!vin_busy(cap)) {
		vin_warn("video%d have been closed!\n", vinc->id);
		return 0;
	}

	if (vin_streaming(cap))
		vin_timer_del(vinc);
#if 0  // cause  kernel NULL pointer
	mutex_lock(&cap->vdev.entity.graph_obj.mdev->graph_mutex);
	if (!cap->pipe.sd[VIN_IND_SENSOR]->entity.use_count) {
		vin_err("%s is not used, video%d cannot be close!\n", cap->pipe.sd[VIN_IND_SENSOR]->name, vinc->id);
		mutex_unlock(&cap->vdev.entity.graph_obj.mdev->graph_mutex);
		return -1;
	}
#endif
	if (vin_streaming(cap)) {
		clear_bit(VIN_STREAM, &cap->state);
		vin_pipeline_call(vinc, set_stream, &cap->pipe, 0);
		vb2_ioctl_streamoff(file, NULL, V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE);
	}

这个位置的代码会造成系统崩溃

	mutex_lock(&cap->vdev.entity.graph_obj.mdev->graph_mutex);
	if (!cap->pipe.sd[VIN_IND_SENSOR]->entity.use_count) {
		vin_err("%s is not used, video%d cannot be close!\n", cap->pipe.sd[VIN_IND_SENSOR]->name, vinc->id);
		mutex_unlock(&cap->vdev.entity.graph_obj.mdev->graph_mutex);
		return -1;
	}