static void hv_compose_msi_msg()

in controller/pci-hyperv.c [1673:1843]

• 122 lines of code
• 14 McCabe index (conditional complexity)

static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
{
	struct hv_pcibus_device *hbus;
	struct vmbus_channel *channel;
	struct hv_pci_dev *hpdev;
	struct pci_bus *pbus;
	struct pci_dev *pdev;
	struct cpumask *dest;
	struct compose_comp_ctxt comp;
	struct tran_int_desc *int_desc;
	struct {
		struct pci_packet pci_pkt;
		union {
			struct pci_create_interrupt v1;
			struct pci_create_interrupt2 v2;
			struct pci_create_interrupt3 v3;
		} int_pkts;
	} __packed ctxt;

	u32 size;
	int ret;

	pdev = msi_desc_to_pci_dev(irq_data_get_msi_desc(data));
	dest = irq_data_get_effective_affinity_mask(data);
	pbus = pdev->bus;
	hbus = container_of(pbus->sysdata, struct hv_pcibus_device, sysdata);
	channel = hbus->hdev->channel;
	hpdev = get_pcichild_wslot(hbus, devfn_to_wslot(pdev->devfn));
	if (!hpdev)
		goto return_null_message;

	/* Free any previous message that might have already been composed. */
	if (data->chip_data) {
		int_desc = data->chip_data;
		data->chip_data = NULL;
		hv_int_desc_free(hpdev, int_desc);
	}

	int_desc = kzalloc(sizeof(*int_desc), GFP_ATOMIC);
	if (!int_desc)
		goto drop_reference;

	memset(&ctxt, 0, sizeof(ctxt));
	init_completion(&comp.comp_pkt.host_event);
	ctxt.pci_pkt.completion_func = hv_pci_compose_compl;
	ctxt.pci_pkt.compl_ctxt = ∁

	switch (hbus->protocol_version) {
	case PCI_PROTOCOL_VERSION_1_1:
		size = hv_compose_msi_req_v1(&ctxt.int_pkts.v1,
					dest,
					hpdev->desc.win_slot.slot,
					hv_msi_get_int_vector(data));
		break;

	case PCI_PROTOCOL_VERSION_1_2:
	case PCI_PROTOCOL_VERSION_1_3:
		size = hv_compose_msi_req_v2(&ctxt.int_pkts.v2,
					dest,
					hpdev->desc.win_slot.slot,
					hv_msi_get_int_vector(data));
		break;

	case PCI_PROTOCOL_VERSION_1_4:
		size = hv_compose_msi_req_v3(&ctxt.int_pkts.v3,
					dest,
					hpdev->desc.win_slot.slot,
					hv_msi_get_int_vector(data));
		break;

	default:
		/* As we only negotiate protocol versions known to this driver,
		 * this path should never hit. However, this is it not a hot
		 * path so we print a message to aid future updates.
		 */
		dev_err(&hbus->hdev->device,
			"Unexpected vPCI protocol, update driver.");
		goto free_int_desc;
	}

	ret = vmbus_sendpacket(hpdev->hbus->hdev->channel, &ctxt.int_pkts,
			       size, (unsigned long)&ctxt.pci_pkt,
			       VM_PKT_DATA_INBAND,
			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
	if (ret) {
		dev_err(&hbus->hdev->device,
			"Sending request for interrupt failed: 0x%x",
			comp.comp_pkt.completion_status);
		goto free_int_desc;
	}

	/*
	 * Prevents hv_pci_onchannelcallback() from running concurrently
	 * in the tasklet.
	 */
	tasklet_disable_in_atomic(&channel->callback_event);

	/*
	 * Since this function is called with IRQ locks held, can't
	 * do normal wait for completion; instead poll.
	 */
	while (!try_wait_for_completion(&comp.comp_pkt.host_event)) {
		unsigned long flags;

		/* 0xFFFF means an invalid PCI VENDOR ID. */
		if (hv_pcifront_get_vendor_id(hpdev) == 0xFFFF) {
			dev_err_once(&hbus->hdev->device,
				     "the device has gone\n");
			goto enable_tasklet;
		}

		/*
		 * Make sure that the ring buffer data structure doesn't get
		 * freed while we dereference the ring buffer pointer.  Test
		 * for the channel's onchannel_callback being NULL within a
		 * sched_lock critical section.  See also the inline comments
		 * in vmbus_reset_channel_cb().
		 */
		spin_lock_irqsave(&channel->sched_lock, flags);
		if (unlikely(channel->onchannel_callback == NULL)) {
			spin_unlock_irqrestore(&channel->sched_lock, flags);
			goto enable_tasklet;
		}
		hv_pci_onchannelcallback(hbus);
		spin_unlock_irqrestore(&channel->sched_lock, flags);

		if (hpdev->state == hv_pcichild_ejecting) {
			dev_err_once(&hbus->hdev->device,
				     "the device is being ejected\n");
			goto enable_tasklet;
		}

		udelay(100);
	}

	tasklet_enable(&channel->callback_event);

	if (comp.comp_pkt.completion_status < 0) {
		dev_err(&hbus->hdev->device,
			"Request for interrupt failed: 0x%x",
			comp.comp_pkt.completion_status);
		goto free_int_desc;
	}

	/*
	 * Record the assignment so that this can be unwound later. Using
	 * irq_set_chip_data() here would be appropriate, but the lock it takes
	 * is already held.
	 */
	*int_desc = comp.int_desc;
	data->chip_data = int_desc;

	/* Pass up the result. */
	msg->address_hi = comp.int_desc.address >> 32;
	msg->address_lo = comp.int_desc.address & 0xffffffff;
	msg->data = comp.int_desc.data;

	put_pcichild(hpdev);
	return;

enable_tasklet:
	tasklet_enable(&channel->callback_event);
free_int_desc:
	kfree(int_desc);
drop_reference:
	put_pcichild(hpdev);
return_null_message:
	msg->address_hi = 0;
	msg->address_lo = 0;
	msg->data = 0;
}