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