static int virtballoon_probe()

in virtio_balloon.c [881:1045]

• 116 lines of code
• 22 McCabe index (conditional complexity)

static int virtballoon_probe(struct virtio_device *vdev)
{
	struct virtio_balloon *vb;
	int err;

	if (!vdev->config->get) {
		dev_err(&vdev->dev, "%s failure: config access disabled\n",
			__func__);
		return -EINVAL;
	}

	vdev->priv = vb = kzalloc(sizeof(*vb), GFP_KERNEL);
	if (!vb) {
		err = -ENOMEM;
		goto out;
	}

	INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func);
	INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func);
	spin_lock_init(&vb->stop_update_lock);
	mutex_init(&vb->balloon_lock);
	init_waitqueue_head(&vb->acked);
	vb->vdev = vdev;

	balloon_devinfo_init(&vb->vb_dev_info);

	err = init_vqs(vb);
	if (err)
		goto out_free_vb;

#ifdef CONFIG_BALLOON_COMPACTION
	balloon_mnt = kern_mount(&balloon_fs);
	if (IS_ERR(balloon_mnt)) {
		err = PTR_ERR(balloon_mnt);
		goto out_del_vqs;
	}

	vb->vb_dev_info.migratepage = virtballoon_migratepage;
	vb->vb_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb);
	if (IS_ERR(vb->vb_dev_info.inode)) {
		err = PTR_ERR(vb->vb_dev_info.inode);
		goto out_kern_unmount;
	}
	vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops;
#endif
	if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
		/*
		 * There is always one entry reserved for cmd id, so the ring
		 * size needs to be at least two to report free page hints.
		 */
		if (virtqueue_get_vring_size(vb->free_page_vq) < 2) {
			err = -ENOSPC;
			goto out_iput;
		}
		vb->balloon_wq = alloc_workqueue("balloon-wq",
					WQ_FREEZABLE | WQ_CPU_INTENSIVE, 0);
		if (!vb->balloon_wq) {
			err = -ENOMEM;
			goto out_iput;
		}
		INIT_WORK(&vb->report_free_page_work, report_free_page_func);
		vb->cmd_id_received_cache = VIRTIO_BALLOON_CMD_ID_STOP;
		vb->cmd_id_active = cpu_to_virtio32(vb->vdev,
						  VIRTIO_BALLOON_CMD_ID_STOP);
		vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
						  VIRTIO_BALLOON_CMD_ID_STOP);
		spin_lock_init(&vb->free_page_list_lock);
		INIT_LIST_HEAD(&vb->free_page_list);
		/*
		 * We're allowed to reuse any free pages, even if they are
		 * still to be processed by the host.
		 */
		err = virtio_balloon_register_shrinker(vb);
		if (err)
			goto out_del_balloon_wq;
	}

	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) {
		vb->oom_nb.notifier_call = virtio_balloon_oom_notify;
		vb->oom_nb.priority = VIRTIO_BALLOON_OOM_NOTIFY_PRIORITY;
		err = register_oom_notifier(&vb->oom_nb);
		if (err < 0)
			goto out_unregister_shrinker;
	}

	if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
		/* Start with poison val of 0 representing general init */
		__u32 poison_val = 0;

		/*
		 * Let the hypervisor know that we are expecting a
		 * specific value to be written back in balloon pages.
		 *
		 * If the PAGE_POISON value was larger than a byte we would
		 * need to byte swap poison_val here to guarantee it is
		 * little-endian. However for now it is a single byte so we
		 * can pass it as-is.
		 */
		if (!want_init_on_free())
			memset(&poison_val, PAGE_POISON, sizeof(poison_val));

		virtio_cwrite_le(vb->vdev, struct virtio_balloon_config,
				 poison_val, &poison_val);
	}

	vb->pr_dev_info.report = virtballoon_free_page_report;
	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) {
		unsigned int capacity;

		capacity = virtqueue_get_vring_size(vb->reporting_vq);
		if (capacity < PAGE_REPORTING_CAPACITY) {
			err = -ENOSPC;
			goto out_unregister_oom;
		}

		/*
		 * The default page reporting order is @pageblock_order, which
		 * corresponds to 512MB in size on ARM64 when 64KB base page
		 * size is used. The page reporting won't be triggered if the
		 * freeing page can't come up with a free area like that huge.
		 * So we specify the page reporting order to 5, corresponding
		 * to 2MB. It helps to avoid THP splitting if 4KB base page
		 * size is used by host.
		 *
		 * Ideally, the page reporting order is selected based on the
		 * host's base page size. However, it needs more work to report
		 * that value. The hard-coded order would be fine currently.
		 */
#if defined(CONFIG_ARM64) && defined(CONFIG_ARM64_64K_PAGES)
		vb->pr_dev_info.order = 5;
#endif

		err = page_reporting_register(&vb->pr_dev_info);
		if (err)
			goto out_unregister_oom;
	}

	virtio_device_ready(vdev);

	if (towards_target(vb))
		virtballoon_changed(vdev);
	return 0;

out_unregister_oom:
	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
		unregister_oom_notifier(&vb->oom_nb);
out_unregister_shrinker:
	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
		virtio_balloon_unregister_shrinker(vb);
out_del_balloon_wq:
	if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
		destroy_workqueue(vb->balloon_wq);
out_iput:
#ifdef CONFIG_BALLOON_COMPACTION
	iput(vb->vb_dev_info.inode);
out_kern_unmount:
	kern_unmount(balloon_mnt);
out_del_vqs:
#endif
	vdev->config->del_vqs(vdev);
out_free_vb:
	kfree(vb);
out:
	return err;
}