static int virtio_dev_probe()

in virtio.c [213:297]

• 59 lines of code
• 16 McCabe index (conditional complexity)

static int virtio_dev_probe(struct device *_d)
{
	int err, i;
	struct virtio_device *dev = dev_to_virtio(_d);
	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
	u64 device_features;
	u64 driver_features;
	u64 driver_features_legacy;

	/* We have a driver! */
	virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);

	/* Figure out what features the device supports. */
	device_features = dev->config->get_features(dev);

	/* Figure out what features the driver supports. */
	driver_features = 0;
	for (i = 0; i < drv->feature_table_size; i++) {
		unsigned int f = drv->feature_table[i];
		BUG_ON(f >= 64);
		driver_features |= (1ULL << f);
	}

	/* Some drivers have a separate feature table for virtio v1.0 */
	if (drv->feature_table_legacy) {
		driver_features_legacy = 0;
		for (i = 0; i < drv->feature_table_size_legacy; i++) {
			unsigned int f = drv->feature_table_legacy[i];
			BUG_ON(f >= 64);
			driver_features_legacy |= (1ULL << f);
		}
	} else {
		driver_features_legacy = driver_features;
	}

	/*
	 * Some devices detect legacy solely via F_VERSION_1. Write
	 * F_VERSION_1 to force LE config space accesses before FEATURES_OK for
	 * these when needed.
	 */
	if (drv->validate && !virtio_legacy_is_little_endian()
			  && device_features & BIT_ULL(VIRTIO_F_VERSION_1)) {
		dev->features = BIT_ULL(VIRTIO_F_VERSION_1);
		dev->config->finalize_features(dev);
	}

	if (device_features & (1ULL << VIRTIO_F_VERSION_1))
		dev->features = driver_features & device_features;
	else
		dev->features = driver_features_legacy & device_features;

	/* Transport features always preserved to pass to finalize_features. */
	for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
		if (device_features & (1ULL << i))
			__virtio_set_bit(dev, i);

	if (drv->validate) {
		err = drv->validate(dev);
		if (err)
			goto err;
	}

	err = virtio_finalize_features(dev);
	if (err)
		goto err;

	err = drv->probe(dev);
	if (err)
		goto err;

	/* If probe didn't do it, mark device DRIVER_OK ourselves. */
	if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
		virtio_device_ready(dev);

	if (drv->scan)
		drv->scan(dev);

	virtio_config_enable(dev);

	return 0;
err:
	virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
	return err;

}