static int pvcalls_front_probe()

in pvcalls-front.c [1127:1242]

• 103 lines of code
• 20 McCabe index (conditional complexity)

static int pvcalls_front_probe(struct xenbus_device *dev,
			  const struct xenbus_device_id *id)
{
	int ret = -ENOMEM, i;
	evtchn_port_t evtchn;
	unsigned int max_page_order, function_calls, len;
	char *versions;
	grant_ref_t gref_head = 0;
	struct xenbus_transaction xbt;
	struct pvcalls_bedata *bedata = NULL;
	struct xen_pvcalls_sring *sring;

	if (pvcalls_front_dev != NULL) {
		dev_err(&dev->dev, "only one PV Calls connection supported\n");
		return -EINVAL;
	}

	versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
	if (IS_ERR(versions))
		return PTR_ERR(versions);
	if (!len)
		return -EINVAL;
	if (strcmp(versions, "1")) {
		kfree(versions);
		return -EINVAL;
	}
	kfree(versions);
	max_page_order = xenbus_read_unsigned(dev->otherend,
					      "max-page-order", 0);
	if (max_page_order < PVCALLS_RING_ORDER)
		return -ENODEV;
	function_calls = xenbus_read_unsigned(dev->otherend,
					      "function-calls", 0);
	/* See XENBUS_FUNCTIONS_CALLS in pvcalls.h */
	if (function_calls != 1)
		return -ENODEV;
	pr_info("%s max-page-order is %u\n", __func__, max_page_order);

	bedata = kzalloc(sizeof(struct pvcalls_bedata), GFP_KERNEL);
	if (!bedata)
		return -ENOMEM;

	dev_set_drvdata(&dev->dev, bedata);
	pvcalls_front_dev = dev;
	init_waitqueue_head(&bedata->inflight_req);
	INIT_LIST_HEAD(&bedata->socket_mappings);
	spin_lock_init(&bedata->socket_lock);
	bedata->irq = -1;
	bedata->ref = -1;

	for (i = 0; i < PVCALLS_NR_RSP_PER_RING; i++)
		bedata->rsp[i].req_id = PVCALLS_INVALID_ID;

	sring = (struct xen_pvcalls_sring *) __get_free_page(GFP_KERNEL |
							     __GFP_ZERO);
	if (!sring)
		goto error;
	SHARED_RING_INIT(sring);
	FRONT_RING_INIT(&bedata->ring, sring, XEN_PAGE_SIZE);

	ret = xenbus_alloc_evtchn(dev, &evtchn);
	if (ret)
		goto error;

	bedata->irq = bind_evtchn_to_irqhandler(evtchn,
						pvcalls_front_event_handler,
						0, "pvcalls-frontend", dev);
	if (bedata->irq < 0) {
		ret = bedata->irq;
		goto error;
	}

	ret = gnttab_alloc_grant_references(1, &gref_head);
	if (ret < 0)
		goto error;
	ret = gnttab_claim_grant_reference(&gref_head);
	if (ret < 0)
		goto error;
	bedata->ref = ret;
	gnttab_grant_foreign_access_ref(bedata->ref, dev->otherend_id,
					virt_to_gfn((void *)sring), 0);

 again:
	ret = xenbus_transaction_start(&xbt);
	if (ret) {
		xenbus_dev_fatal(dev, ret, "starting transaction");
		goto error;
	}
	ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1);
	if (ret)
		goto error_xenbus;
	ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", bedata->ref);
	if (ret)
		goto error_xenbus;
	ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
			    evtchn);
	if (ret)
		goto error_xenbus;
	ret = xenbus_transaction_end(xbt, 0);
	if (ret) {
		if (ret == -EAGAIN)
			goto again;
		xenbus_dev_fatal(dev, ret, "completing transaction");
		goto error;
	}
	xenbus_switch_state(dev, XenbusStateInitialised);

	return 0;

 error_xenbus:
	xenbus_transaction_end(xbt, 1);
	xenbus_dev_fatal(dev, ret, "writing xenstore");
 error:
	pvcalls_front_remove(dev);
	return ret;
}