static int vp_find_vqs_msix()

in virtio_pci_common.c [313:385]

• 62 lines of code
• 17 McCabe index (conditional complexity)

static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
		struct virtqueue *vqs[], vq_callback_t *callbacks[],
		const char * const names[], bool per_vq_vectors,
		const bool *ctx,
		struct irq_affinity *desc)
{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
	u16 msix_vec;
	int i, err, nvectors, allocated_vectors, queue_idx = 0;

	vp_dev->vqs = kcalloc(nvqs, sizeof(*vp_dev->vqs), GFP_KERNEL);
	if (!vp_dev->vqs)
		return -ENOMEM;

	if (per_vq_vectors) {
		/* Best option: one for change interrupt, one per vq. */
		nvectors = 1;
		for (i = 0; i < nvqs; ++i)
			if (names[i] && callbacks[i])
				++nvectors;
	} else {
		/* Second best: one for change, shared for all vqs. */
		nvectors = 2;
	}

	err = vp_request_msix_vectors(vdev, nvectors, per_vq_vectors,
				      per_vq_vectors ? desc : NULL);
	if (err)
		goto error_find;

	vp_dev->per_vq_vectors = per_vq_vectors;
	allocated_vectors = vp_dev->msix_used_vectors;
	for (i = 0; i < nvqs; ++i) {
		if (!names[i]) {
			vqs[i] = NULL;
			continue;
		}

		if (!callbacks[i])
			msix_vec = VIRTIO_MSI_NO_VECTOR;
		else if (vp_dev->per_vq_vectors)
			msix_vec = allocated_vectors++;
		else
			msix_vec = VP_MSIX_VQ_VECTOR;
		vqs[i] = vp_setup_vq(vdev, queue_idx++, callbacks[i], names[i],
				     ctx ? ctx[i] : false,
				     msix_vec);
		if (IS_ERR(vqs[i])) {
			err = PTR_ERR(vqs[i]);
			goto error_find;
		}

		if (!vp_dev->per_vq_vectors || msix_vec == VIRTIO_MSI_NO_VECTOR)
			continue;

		/* allocate per-vq irq if available and necessary */
		snprintf(vp_dev->msix_names[msix_vec],
			 sizeof *vp_dev->msix_names,
			 "%s-%s",
			 dev_name(&vp_dev->vdev.dev), names[i]);
		err = request_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec),
				  vring_interrupt, IRQF_NO_AUTOEN,
				  vp_dev->msix_names[msix_vec],
				  vqs[i]);
		if (err)
			goto error_find;
	}
	return 0;

error_find:
	vp_del_vqs(vdev);
	return err;
}