core.c

	case NETDEV_UNREGISTER:
		/*
		 * It is possible to get NETDEV_UNREGISTER
		 * multiple times. To detect that, check
		 * that the interface is still on the list
		 * of registered interfaces, and only then
		 * remove and clean it up.
		 */
		if (!list_empty(&wdev->list)) {
			sysfs_remove_link(&dev->dev.kobj, "phy80211");
			list_del_rcu(&wdev->list);
			rdev->devlist_generation++;
			cfg80211_mlme_purge_registrations(wdev);
#ifdef CONFIG_CFG80211_WEXT
			kfree(wdev->wext.keys);
#endif
		}
		/*
		 * synchronise (so that we won't find this netdev
		 * from other code any more) and then clear the list
		 * head so that the above code can safely check for
		 * !list_empty() to avoid double-cleanup.
		 */
		synchronize_rcu();
		INIT_LIST_HEAD(&wdev->list);
		/*
		 * Ensure that all events have been processed and
		 * freed.
		 */
		cfg80211_process_wdev_events(wdev);

		if (WARN_ON(wdev->current_bss)) {
			cfg80211_unhold_bss(wdev->current_bss);
			cfg80211_put_bss(wdev->wiphy, &wdev->current_bss->pub);
			wdev->current_bss = NULL;
		}
		break;
	case NETDEV_PRE_UP:
		if (!(wdev->wiphy->interface_modes & BIT(wdev->iftype)))
			return notifier_from_errno(-EOPNOTSUPP);
		if (rfkill_blocked(rdev->rfkill))
			return notifier_from_errno(-ERFKILL);
		break;
	default:
		return NOTIFY_DONE;
	}

	return NOTIFY_OK;
}

static struct notifier_block cfg80211_netdev_notifier = {
	.notifier_call = cfg80211_netdev_notifier_call,
};

static void __net_exit cfg80211_pernet_exit(struct net *net)
{
	struct cfg80211_registered_device *rdev;

	rtnl_lock();
	list_for_each_entry(rdev, &cfg80211_rdev_list, list) {
		if (net_eq(wiphy_net(&rdev->wiphy), net))
			WARN_ON(cfg80211_switch_netns(rdev, &init_net));
	}
	rtnl_unlock();
}

static struct pernet_operations cfg80211_pernet_ops = {
	.exit = cfg80211_pernet_exit,
};

static int __init cfg80211_init(void)
{
	int err;

	err = register_pernet_device(&cfg80211_pernet_ops);
	if (err)
		goto out_fail_pernet;

	err = wiphy_sysfs_init();
	if (err)
		goto out_fail_sysfs;

	err = register_netdevice_notifier(&cfg80211_netdev_notifier);
	if (err)
		goto out_fail_notifier;

	err = nl80211_init();
	if (err)
		goto out_fail_nl80211;

	ieee80211_debugfs_dir = debugfs_create_dir("ieee80211", NULL);

	err = regulatory_init();
	if (err)
		goto out_fail_reg;

	cfg80211_wq = create_singlethread_workqueue("cfg80211");
	if (!cfg80211_wq) {
		err = -ENOMEM;
		goto out_fail_wq;
	}

	return 0;

out_fail_wq:
	regulatory_exit();
out_fail_reg:
	debugfs_remove(ieee80211_debugfs_dir);
out_fail_nl80211:
	unregister_netdevice_notifier(&cfg80211_netdev_notifier);
out_fail_notifier:
	wiphy_sysfs_exit();
out_fail_sysfs:
	unregister_pernet_device(&cfg80211_pernet_ops);
out_fail_pernet:
	return err;
}
subsys_initcall(cfg80211_init);

static void __exit cfg80211_exit(void)
{
	debugfs_remove(ieee80211_debugfs_dir);
	nl80211_exit();
	unregister_netdevice_notifier(&cfg80211_netdev_notifier);
	wiphy_sysfs_exit();
	regulatory_exit();
	unregister_pernet_device(&cfg80211_pernet_ops);
	destroy_workqueue(cfg80211_wq);
}
module_exit(cfg80211_exit);