static int init_vqs()

in virtio_balloon.c [497:570]

• 54 lines of code
• 9 McCabe index (conditional complexity)

static int init_vqs(struct virtio_balloon *vb)
{
	struct virtqueue *vqs[VIRTIO_BALLOON_VQ_MAX];
	vq_callback_t *callbacks[VIRTIO_BALLOON_VQ_MAX];
	const char *names[VIRTIO_BALLOON_VQ_MAX];
	int err;

	/*
	 * Inflateq and deflateq are used unconditionally. The names[]
	 * will be NULL if the related feature is not enabled, which will
	 * cause no allocation for the corresponding virtqueue in find_vqs.
	 */
	callbacks[VIRTIO_BALLOON_VQ_INFLATE] = balloon_ack;
	names[VIRTIO_BALLOON_VQ_INFLATE] = "inflate";
	callbacks[VIRTIO_BALLOON_VQ_DEFLATE] = balloon_ack;
	names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate";
	callbacks[VIRTIO_BALLOON_VQ_STATS] = NULL;
	names[VIRTIO_BALLOON_VQ_STATS] = NULL;
	callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
	names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
	names[VIRTIO_BALLOON_VQ_REPORTING] = NULL;

	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
		names[VIRTIO_BALLOON_VQ_STATS] = "stats";
		callbacks[VIRTIO_BALLOON_VQ_STATS] = stats_request;
	}

	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
		names[VIRTIO_BALLOON_VQ_FREE_PAGE] = "free_page_vq";
		callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
	}

	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) {
		names[VIRTIO_BALLOON_VQ_REPORTING] = "reporting_vq";
		callbacks[VIRTIO_BALLOON_VQ_REPORTING] = balloon_ack;
	}

	err = virtio_find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX, vqs,
			      callbacks, names, NULL);
	if (err)
		return err;

	vb->inflate_vq = vqs[VIRTIO_BALLOON_VQ_INFLATE];
	vb->deflate_vq = vqs[VIRTIO_BALLOON_VQ_DEFLATE];
	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
		struct scatterlist sg;
		unsigned int num_stats;
		vb->stats_vq = vqs[VIRTIO_BALLOON_VQ_STATS];

		/*
		 * Prime this virtqueue with one buffer so the hypervisor can
		 * use it to signal us later (it can't be broken yet!).
		 */
		num_stats = update_balloon_stats(vb);

		sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats);
		err = virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb,
					   GFP_KERNEL);
		if (err) {
			dev_warn(&vb->vdev->dev, "%s: add stat_vq failed\n",
				 __func__);
			return err;
		}
		virtqueue_kick(vb->stats_vq);
	}

	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
		vb->free_page_vq = vqs[VIRTIO_BALLOON_VQ_FREE_PAGE];

	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING))
		vb->reporting_vq = vqs[VIRTIO_BALLOON_VQ_REPORTING];

	return 0;
}