c
int spi_sync(struct spi_device *spi, struct spi_message *message)
{
    int ret;
    mutex_lock(&spi->controller->bus_lock_mutex);
    ret = __spi_sync(spi, message);
    if (!spi->controller->is_being_freed) {
        mutex_unlock(&spi->controller->bus_lock_mutex);
    }
    return ret;
}
