static int hdm_enqueue()

in most_usb.c [457:533]
67 lines of code
13 McCabe index (conditional complexity)

static int hdm_enqueue(struct most_interface *iface, int channel,
		       struct mbo *mbo)
{
	struct most_dev *mdev = to_mdev(iface);
	struct most_channel_config *conf;
	int retval = 0;
	struct urb *urb;
	unsigned long length;
	void *virt_address;

	if (!mbo)
		return -EINVAL;
	if (iface->num_channels <= channel || channel < 0)
		return -ECHRNG;

	urb = usb_alloc_urb(NO_ISOCHRONOUS_URB, GFP_KERNEL);
	if (!urb)
		return -ENOMEM;

	conf = &mdev->conf[channel];

	mutex_lock(&mdev->io_mutex);
	if (!mdev->usb_device) {
		retval = -ENODEV;
		goto err_free_urb;
	}

	if ((conf->direction & MOST_CH_TX) && mdev->padding_active[channel] &&
	    hdm_add_padding(mdev, channel, mbo)) {
		retval = -EINVAL;
		goto err_free_urb;
	}

	urb->transfer_dma = mbo->bus_address;
	virt_address = mbo->virt_address;
	length = mbo->buffer_length;

	if (conf->direction & MOST_CH_TX) {
		usb_fill_bulk_urb(urb, mdev->usb_device,
				  usb_sndbulkpipe(mdev->usb_device,
						  mdev->ep_address[channel]),
				  virt_address,
				  length,
				  hdm_write_completion,
				  mbo);
		if (conf->data_type != MOST_CH_ISOC &&
		    conf->data_type != MOST_CH_SYNC)
			urb->transfer_flags |= URB_ZERO_PACKET;
	} else {
		usb_fill_bulk_urb(urb, mdev->usb_device,
				  usb_rcvbulkpipe(mdev->usb_device,
						  mdev->ep_address[channel]),
				  virt_address,
				  length + conf->extra_len,
				  hdm_read_completion,
				  mbo);
	}
	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;

	usb_anchor_urb(urb, &mdev->busy_urbs[channel]);

	retval = usb_submit_urb(urb, GFP_KERNEL);
	if (retval) {
		dev_err(&mdev->usb_device->dev,
			"URB submit failed with error %d.\n", retval);
		goto err_unanchor_urb;
	}
	mutex_unlock(&mdev->io_mutex);
	return 0;

err_unanchor_urb:
	usb_unanchor_urb(urb);
err_free_urb:
	usb_free_urb(urb);
	mutex_unlock(&mdev->io_mutex);
	return retval;
}