drivers/infiniband/core/addr.c - kernel/common - Git at Google

 /*
  * Copyright (c) 2005 Voltaire Inc.  All rights reserved.
  * Copyright (c) 2002-2005, Network Appliance, Inc. All rights reserved.
  * Copyright (c) 1999-2005, Mellanox Technologies, Inc. All rights reserved.
  * Copyright (c) 2005 Intel Corporation.  All rights reserved.
  *
  * This Software is licensed under one of the following licenses:
  *
  * 1) under the terms of the "Common Public License 1.0" a copy of which is
  *    available from the Open Source Initiative, see
  *    http://www.opensource.org/licenses/cpl.php.
  *
  * 2) under the terms of the "The BSD License" a copy of which is
  *    available from the Open Source Initiative, see
  *    http://www.opensource.org/licenses/bsd-license.php.
  *
  * 3) under the terms of the "GNU General Public License (GPL) Version 2" a
  *    copy of which is available from the Open Source Initiative, see
  *    http://www.opensource.org/licenses/gpl-license.php.
  *
  * Licensee has the right to choose one of the above licenses.
  *
  * Redistributions of source code must retain the above copyright
  * notice and one of the license notices.
  *
  * Redistributions in binary form must reproduce both the above copyright
  * notice, one of the license notices in the documentation
  * and/or other materials provided with the distribution.
  */

 #include <linux/mutex.h>
 #include <linux/inetdevice.h>
 #include <linux/workqueue.h>
 #include <linux/if_arp.h>
 #include <net/arp.h>
 #include <net/neighbour.h>
 #include <net/route.h>
 #include <net/netevent.h>
 #include <rdma/ib_addr.h>

 MODULE_AUTHOR("Sean Hefty");
 MODULE_DESCRIPTION("IB Address Translation");
 MODULE_LICENSE("Dual BSD/GPL");

 struct addr_req {
 	struct list_head list;
 	struct sockaddr src_addr;
 	struct sockaddr dst_addr;
 	struct rdma_dev_addr *addr;
 	struct rdma_addr_client *client;
 	void *context;
 	void (*callback)(int status, struct sockaddr *src_addr,
 			 struct rdma_dev_addr *addr, void *context);
 	unsigned long timeout;
 	int status;
 };

 static void process_req(struct work_struct *work);

 static DEFINE_MUTEX(lock);
 static LIST_HEAD(req_list);
 static DECLARE_DELAYED_WORK(work, process_req);
 static struct workqueue_struct *addr_wq;

 void rdma_addr_register_client(struct rdma_addr_client *client)
 {
 	atomic_set(&client->refcount, 1);
 	init_completion(&client->comp);
 }
 EXPORT_SYMBOL(rdma_addr_register_client);

 static inline void put_client(struct rdma_addr_client *client)
 {
 	if (atomic_dec_and_test(&client->refcount))
 		complete(&client->comp);
 }

 void rdma_addr_unregister_client(struct rdma_addr_client *client)
 {
 	put_client(client);
 	wait_for_completion(&client->comp);
 }
 EXPORT_SYMBOL(rdma_addr_unregister_client);

 int rdma_copy_addr(struct rdma_dev_addr *dev_addr, struct net_device *dev,
 		     const unsigned char *dst_dev_addr)
 {
 	switch (dev->type) {
 	case ARPHRD_INFINIBAND:
 		dev_addr->dev_type = RDMA_NODE_IB_CA;
 		break;
 	case ARPHRD_ETHER:
 		dev_addr->dev_type = RDMA_NODE_RNIC;
 		break;
 	default:
 		return -EADDRNOTAVAIL;
 	}

 	memcpy(dev_addr->src_dev_addr, dev->dev_addr, MAX_ADDR_LEN);
 	memcpy(dev_addr->broadcast, dev->broadcast, MAX_ADDR_LEN);
 	if (dst_dev_addr)
 		memcpy(dev_addr->dst_dev_addr, dst_dev_addr, MAX_ADDR_LEN);
 	return 0;
 }
 EXPORT_SYMBOL(rdma_copy_addr);

 int rdma_translate_ip(struct sockaddr *addr, struct rdma_dev_addr *dev_addr)
 {
 	struct net_device *dev;
 	__be32 ip = ((struct sockaddr_in *) addr)->sin_addr.s_addr;
 	int ret;

 	dev = ip_dev_find(ip);
 	if (!dev)
 		return -EADDRNOTAVAIL;

 	ret = rdma_copy_addr(dev_addr, dev, NULL);
 	dev_put(dev);
 	return ret;
 }
 EXPORT_SYMBOL(rdma_translate_ip);

 static void set_timeout(unsigned long time)
 {
 	unsigned long delay;

 	cancel_delayed_work(&work);

 	delay = time - jiffies;
 	if ((long)delay <= 0)
 		delay = 1;

 	queue_delayed_work(addr_wq, &work, delay);
 }

 static void queue_req(struct addr_req *req)
 {
 	struct addr_req *temp_req;

 	mutex_lock(&lock);
 	list_for_each_entry_reverse(temp_req, &req_list, list) {
 		if (time_after_eq(req->timeout, temp_req->timeout))
 			break;
 	}

 	list_add(&req->list, &temp_req->list);

 	if (req_list.next == &req->list)
 		set_timeout(req->timeout);
 	mutex_unlock(&lock);
 }

 static void addr_send_arp(struct sockaddr_in *dst_in)
 {
 	struct rtable *rt;
 	struct flowi fl;
 	u32 dst_ip = dst_in->sin_addr.s_addr;

 	memset(&fl, 0, sizeof fl);
 	fl.nl_u.ip4_u.daddr = dst_ip;
 	if (ip_route_output_key(&rt, &fl))
 		return;

 	arp_send(ARPOP_REQUEST, ETH_P_ARP, rt->rt_gateway, rt->idev->dev,
 		 rt->rt_src, NULL, rt->idev->dev->dev_addr, NULL);
 	ip_rt_put(rt);
 }

 static int addr_resolve_remote(struct sockaddr_in *src_in,
 			       struct sockaddr_in *dst_in,
 			       struct rdma_dev_addr *addr)
 {
 	u32 src_ip = src_in->sin_addr.s_addr;
 	u32 dst_ip = dst_in->sin_addr.s_addr;
 	struct flowi fl;
 	struct rtable *rt;
 	struct neighbour *neigh;
 	int ret;

 	memset(&fl, 0, sizeof fl);
 	fl.nl_u.ip4_u.daddr = dst_ip;
 	fl.nl_u.ip4_u.saddr = src_ip;
 	ret = ip_route_output_key(&rt, &fl);
 	if (ret)
 		goto out;

 	/* If the device does ARP internally, return 'done' */
 	if (rt->idev->dev->flags & IFF_NOARP) {
 		rdma_copy_addr(addr, rt->idev->dev, NULL);
 		goto put;
 	}

 	neigh = neigh_lookup(&arp_tbl, &rt->rt_gateway, rt->idev->dev);
 	if (!neigh) {
 		ret = -ENODATA;
 		goto put;
 	}

 	if (!(neigh->nud_state & NUD_VALID)) {
 		ret = -ENODATA;
 		goto release;
 	}

 	if (!src_ip) {
 		src_in->sin_family = dst_in->sin_family;
 		src_in->sin_addr.s_addr = rt->rt_src;
 	}

 	ret = rdma_copy_addr(addr, neigh->dev, neigh->ha);
 release:
 	neigh_release(neigh);
 put:
 	ip_rt_put(rt);
 out:
 	return ret;
 }

 static void process_req(struct work_struct *work)
 {
 	struct addr_req *req, *temp_req;
 	struct sockaddr_in *src_in, *dst_in;
 	struct list_head done_list;

 	INIT_LIST_HEAD(&done_list);

 	mutex_lock(&lock);
 	list_for_each_entry_safe(req, temp_req, &req_list, list) {
 		if (req->status == -ENODATA) {
 			src_in = (struct sockaddr_in *) &req->src_addr;
 			dst_in = (struct sockaddr_in *) &req->dst_addr;
 			req->status = addr_resolve_remote(src_in, dst_in,
 							  req->addr);
 			if (req->status && time_after_eq(jiffies, req->timeout))
 				req->status = -ETIMEDOUT;
 			else if (req->status == -ENODATA)
 				continue;
 		}
 		list_move_tail(&req->list, &done_list);
 	}

 	if (!list_empty(&req_list)) {
 		req = list_entry(req_list.next, struct addr_req, list);
 		set_timeout(req->timeout);
 	}
 	mutex_unlock(&lock);

 	list_for_each_entry_safe(req, temp_req, &done_list, list) {
 		list_del(&req->list);
 		req->callback(req->status, &req->src_addr, req->addr,
 			      req->context);
 		put_client(req->client);
 		kfree(req);
 	}
 }

 static int addr_resolve_local(struct sockaddr_in *src_in,
 			      struct sockaddr_in *dst_in,
 			      struct rdma_dev_addr *addr)
 {
 	struct net_device *dev;
 	u32 src_ip = src_in->sin_addr.s_addr;
 	__be32 dst_ip = dst_in->sin_addr.s_addr;
 	int ret;

 	dev = ip_dev_find(dst_ip);
 	if (!dev)
 		return -EADDRNOTAVAIL;

 	if (ZERONET(src_ip)) {
 		src_in->sin_family = dst_in->sin_family;
 		src_in->sin_addr.s_addr = dst_ip;
 		ret = rdma_copy_addr(addr, dev, dev->dev_addr);
 	} else if (LOOPBACK(src_ip)) {
 		ret = rdma_translate_ip((struct sockaddr *)dst_in, addr);
 		if (!ret)
 			memcpy(addr->dst_dev_addr, dev->dev_addr, MAX_ADDR_LEN);
 	} else {
 		ret = rdma_translate_ip((struct sockaddr *)src_in, addr);
 		if (!ret)
 			memcpy(addr->dst_dev_addr, dev->dev_addr, MAX_ADDR_LEN);
 	}

 	dev_put(dev);
 	return ret;
 }

 int rdma_resolve_ip(struct rdma_addr_client *client,
 		    struct sockaddr *src_addr, struct sockaddr *dst_addr,
 		    struct rdma_dev_addr *addr, int timeout_ms,
 		    void (*callback)(int status, struct sockaddr *src_addr,
 				     struct rdma_dev_addr *addr, void *context),
 		    void *context)
 {
 	struct sockaddr_in *src_in, *dst_in;
 	struct addr_req *req;
 	int ret = 0;

 	req = kmalloc(sizeof *req, GFP_KERNEL);
 	if (!req)
 		return -ENOMEM;
 	memset(req, 0, sizeof *req);

 	if (src_addr)
 		memcpy(&req->src_addr, src_addr, ip_addr_size(src_addr));
 	memcpy(&req->dst_addr, dst_addr, ip_addr_size(dst_addr));
 	req->addr = addr;
 	req->callback = callback;
 	req->context = context;
 	req->client = client;
 	atomic_inc(&client->refcount);

 	src_in = (struct sockaddr_in *) &req->src_addr;
 	dst_in = (struct sockaddr_in *) &req->dst_addr;

 	req->status = addr_resolve_local(src_in, dst_in, addr);
 	if (req->status == -EADDRNOTAVAIL)
 		req->status = addr_resolve_remote(src_in, dst_in, addr);

 	switch (req->status) {
 	case 0:
 		req->timeout = jiffies;
 		queue_req(req);
 		break;
 	case -ENODATA:
 		req->timeout = msecs_to_jiffies(timeout_ms) + jiffies;
 		queue_req(req);
 		addr_send_arp(dst_in);
 		break;
 	default:
 		ret = req->status;
 		atomic_dec(&client->refcount);
 		kfree(req);
 		break;
 	}
 	return ret;
 }
 EXPORT_SYMBOL(rdma_resolve_ip);

 void rdma_addr_cancel(struct rdma_dev_addr *addr)
 {
 	struct addr_req *req, *temp_req;

 	mutex_lock(&lock);
 	list_for_each_entry_safe(req, temp_req, &req_list, list) {
 		if (req->addr == addr) {
 			req->status = -ECANCELED;
 			req->timeout = jiffies;
 			list_move(&req->list, &req_list);
 			set_timeout(req->timeout);
 			break;
 		}
 	}
 	mutex_unlock(&lock);
 }
 EXPORT_SYMBOL(rdma_addr_cancel);

 static int netevent_callback(struct notifier_block *self, unsigned long event,
 	void *ctx)
 {
 	if (event == NETEVENT_NEIGH_UPDATE) {
 		struct neighbour *neigh = ctx;

 		if (neigh->nud_state & NUD_VALID) {
 			set_timeout(jiffies);
 		}
 	}
 	return 0;
 }

 static struct notifier_block nb = {
 	.notifier_call = netevent_callback
 };

 static int addr_init(void)
 {
 	addr_wq = create_singlethread_workqueue("ib_addr");
 	if (!addr_wq)
 		return -ENOMEM;

 	register_netevent_notifier(&nb);
 	return 0;
 }

 static void addr_cleanup(void)
 {
 	unregister_netevent_notifier(&nb);
 	destroy_workqueue(addr_wq);
 }

 module_init(addr_init);
 module_exit(addr_cleanup);
	/*
	* Copyright (c) 2005 Voltaire Inc. All rights reserved.
	* Copyright (c) 2002-2005, Network Appliance, Inc. All rights reserved.
	* Copyright (c) 1999-2005, Mellanox Technologies, Inc. All rights reserved.
	* Copyright (c) 2005 Intel Corporation. All rights reserved.
	*
	* This Software is licensed under one of the following licenses:
	*
	* 1) under the terms of the "Common Public License 1.0" a copy of which is
	* available from the Open Source Initiative, see
	* http://www.opensource.org/licenses/cpl.php.
	*
	* 2) under the terms of the "The BSD License" a copy of which is
	* available from the Open Source Initiative, see
	* http://www.opensource.org/licenses/bsd-license.php.
	*
	* 3) under the terms of the "GNU General Public License (GPL) Version 2" a
	* copy of which is available from the Open Source Initiative, see
	* http://www.opensource.org/licenses/gpl-license.php.
	*
	* Licensee has the right to choose one of the above licenses.
	*
	* Redistributions of source code must retain the above copyright
	* notice and one of the license notices.
	*
	* Redistributions in binary form must reproduce both the above copyright
	* notice, one of the license notices in the documentation
	* and/or other materials provided with the distribution.
	*/

	#include <linux/mutex.h>
	#include <linux/inetdevice.h>
	#include <linux/workqueue.h>
	#include <linux/if_arp.h>
	#include <net/arp.h>
	#include <net/neighbour.h>
	#include <net/route.h>
	#include <net/netevent.h>
	#include <rdma/ib_addr.h>

	MODULE_AUTHOR("Sean Hefty");
	MODULE_DESCRIPTION("IB Address Translation");
	MODULE_LICENSE("Dual BSD/GPL");

	struct addr_req {
	struct list_head list;
	struct sockaddr src_addr;
	struct sockaddr dst_addr;
	struct rdma_dev_addr *addr;
	struct rdma_addr_client *client;
	void *context;
	void (callback)(int status, struct sockaddr src_addr,
	struct rdma_dev_addr addr, void context);
	unsigned long timeout;
	int status;
	};

	static void process_req(struct work_struct *work);

	static DEFINE_MUTEX(lock);
	static LIST_HEAD(req_list);
	static DECLARE_DELAYED_WORK(work, process_req);
	static struct workqueue_struct *addr_wq;

	void rdma_addr_register_client(struct rdma_addr_client *client)
	{
	atomic_set(&client->refcount, 1);
	init_completion(&client->comp);
	}
	EXPORT_SYMBOL(rdma_addr_register_client);

	static inline void put_client(struct rdma_addr_client *client)
	{
	if (atomic_dec_and_test(&client->refcount))
	complete(&client->comp);
	}

	void rdma_addr_unregister_client(struct rdma_addr_client *client)
	{
	put_client(client);
	wait_for_completion(&client->comp);
	}
	EXPORT_SYMBOL(rdma_addr_unregister_client);

	int rdma_copy_addr(struct rdma_dev_addr dev_addr, struct net_device dev,
	const unsigned char *dst_dev_addr)
	{
	switch (dev->type) {
	case ARPHRD_INFINIBAND:
	dev_addr->dev_type = RDMA_NODE_IB_CA;
	break;
	case ARPHRD_ETHER:
	dev_addr->dev_type = RDMA_NODE_RNIC;
	break;
	default:
	return -EADDRNOTAVAIL;
	}

	memcpy(dev_addr->src_dev_addr, dev->dev_addr, MAX_ADDR_LEN);
	memcpy(dev_addr->broadcast, dev->broadcast, MAX_ADDR_LEN);
	if (dst_dev_addr)
	memcpy(dev_addr->dst_dev_addr, dst_dev_addr, MAX_ADDR_LEN);
	return 0;
	}
	EXPORT_SYMBOL(rdma_copy_addr);

	int rdma_translate_ip(struct sockaddr addr, struct rdma_dev_addr dev_addr)
	{
	struct net_device *dev;
	__be32 ip = ((struct sockaddr_in *) addr)->sin_addr.s_addr;
	int ret;

	dev = ip_dev_find(ip);
	if (!dev)
	return -EADDRNOTAVAIL;

	ret = rdma_copy_addr(dev_addr, dev, NULL);
	dev_put(dev);
	return ret;
	}
	EXPORT_SYMBOL(rdma_translate_ip);

	static void set_timeout(unsigned long time)
	{
	unsigned long delay;

	cancel_delayed_work(&work);

	delay = time - jiffies;
	if ((long)delay <= 0)
	delay = 1;

	queue_delayed_work(addr_wq, &work, delay);
	}

	static void queue_req(struct addr_req *req)
	{
	struct addr_req *temp_req;

	mutex_lock(&lock);
	list_for_each_entry_reverse(temp_req, &req_list, list) {
	if (time_after_eq(req->timeout, temp_req->timeout))
	break;
	}

	list_add(&req->list, &temp_req->list);

	if (req_list.next == &req->list)
	set_timeout(req->timeout);
	mutex_unlock(&lock);
	}

	static void addr_send_arp(struct sockaddr_in *dst_in)
	{
	struct rtable *rt;
	struct flowi fl;
	u32 dst_ip = dst_in->sin_addr.s_addr;

	memset(&fl, 0, sizeof fl);
	fl.nl_u.ip4_u.daddr = dst_ip;
	if (ip_route_output_key(&rt, &fl))
	return;

	arp_send(ARPOP_REQUEST, ETH_P_ARP, rt->rt_gateway, rt->idev->dev,
	rt->rt_src, NULL, rt->idev->dev->dev_addr, NULL);
	ip_rt_put(rt);
	}

	static int addr_resolve_remote(struct sockaddr_in *src_in,
	struct sockaddr_in *dst_in,
	struct rdma_dev_addr *addr)
	{
	u32 src_ip = src_in->sin_addr.s_addr;
	u32 dst_ip = dst_in->sin_addr.s_addr;
	struct flowi fl;
	struct rtable *rt;
	struct neighbour *neigh;
	int ret;

	memset(&fl, 0, sizeof fl);
	fl.nl_u.ip4_u.daddr = dst_ip;
	fl.nl_u.ip4_u.saddr = src_ip;
	ret = ip_route_output_key(&rt, &fl);
	if (ret)
	goto out;

	/* If the device does ARP internally, return 'done' */
	if (rt->idev->dev->flags & IFF_NOARP) {
	rdma_copy_addr(addr, rt->idev->dev, NULL);
	goto put;
	}

	neigh = neigh_lookup(&arp_tbl, &rt->rt_gateway, rt->idev->dev);
	if (!neigh) {
	ret = -ENODATA;
	goto put;
	}

	if (!(neigh->nud_state & NUD_VALID)) {
	ret = -ENODATA;
	goto release;
	}

	if (!src_ip) {
	src_in->sin_family = dst_in->sin_family;
	src_in->sin_addr.s_addr = rt->rt_src;
	}

	ret = rdma_copy_addr(addr, neigh->dev, neigh->ha);
	release:
	neigh_release(neigh);
	put:
	ip_rt_put(rt);
	out:
	return ret;
	}

	static void process_req(struct work_struct *work)
	{
	struct addr_req req, temp_req;
	struct sockaddr_in src_in, dst_in;
	struct list_head done_list;

	INIT_LIST_HEAD(&done_list);

	mutex_lock(&lock);
	list_for_each_entry_safe(req, temp_req, &req_list, list) {
	if (req->status == -ENODATA) {
	src_in = (struct sockaddr_in *) &req->src_addr;
	dst_in = (struct sockaddr_in *) &req->dst_addr;
	req->status = addr_resolve_remote(src_in, dst_in,
	req->addr);
	if (req->status && time_after_eq(jiffies, req->timeout))
	req->status = -ETIMEDOUT;
	else if (req->status == -ENODATA)
	continue;
	}
	list_move_tail(&req->list, &done_list);
	}

	if (!list_empty(&req_list)) {
	req = list_entry(req_list.next, struct addr_req, list);
	set_timeout(req->timeout);
	}
	mutex_unlock(&lock);

	list_for_each_entry_safe(req, temp_req, &done_list, list) {
	list_del(&req->list);
	req->callback(req->status, &req->src_addr, req->addr,
	req->context);
	put_client(req->client);
	kfree(req);
	}
	}

	static int addr_resolve_local(struct sockaddr_in *src_in,
	struct sockaddr_in *dst_in,
	struct rdma_dev_addr *addr)
	{
	struct net_device *dev;
	u32 src_ip = src_in->sin_addr.s_addr;
	__be32 dst_ip = dst_in->sin_addr.s_addr;
	int ret;

	dev = ip_dev_find(dst_ip);
	if (!dev)
	return -EADDRNOTAVAIL;

	if (ZERONET(src_ip)) {
	src_in->sin_family = dst_in->sin_family;
	src_in->sin_addr.s_addr = dst_ip;
	ret = rdma_copy_addr(addr, dev, dev->dev_addr);
	} else if (LOOPBACK(src_ip)) {
	ret = rdma_translate_ip((struct sockaddr *)dst_in, addr);
	if (!ret)
	memcpy(addr->dst_dev_addr, dev->dev_addr, MAX_ADDR_LEN);
	} else {
	ret = rdma_translate_ip((struct sockaddr *)src_in, addr);
	if (!ret)
	memcpy(addr->dst_dev_addr, dev->dev_addr, MAX_ADDR_LEN);
	}

	dev_put(dev);
	return ret;
	}

	int rdma_resolve_ip(struct rdma_addr_client *client,
	struct sockaddr src_addr, struct sockaddr dst_addr,
	struct rdma_dev_addr *addr, int timeout_ms,
	void (callback)(int status, struct sockaddr src_addr,
	struct rdma_dev_addr addr, void context),
	void *context)
	{
	struct sockaddr_in src_in, dst_in;
	struct addr_req *req;
	int ret = 0;

	req = kmalloc(sizeof *req, GFP_KERNEL);
	if (!req)
	return -ENOMEM;
	memset(req, 0, sizeof *req);

	if (src_addr)
	memcpy(&req->src_addr, src_addr, ip_addr_size(src_addr));
	memcpy(&req->dst_addr, dst_addr, ip_addr_size(dst_addr));
	req->addr = addr;
	req->callback = callback;
	req->context = context;
	req->client = client;
	atomic_inc(&client->refcount);

	src_in = (struct sockaddr_in *) &req->src_addr;
	dst_in = (struct sockaddr_in *) &req->dst_addr;

	req->status = addr_resolve_local(src_in, dst_in, addr);
	if (req->status == -EADDRNOTAVAIL)
	req->status = addr_resolve_remote(src_in, dst_in, addr);

	switch (req->status) {
	case 0:
	req->timeout = jiffies;
	queue_req(req);
	break;
	case -ENODATA:
	req->timeout = msecs_to_jiffies(timeout_ms) + jiffies;
	queue_req(req);
	addr_send_arp(dst_in);
	break;
	default:
	ret = req->status;
	atomic_dec(&client->refcount);
	kfree(req);
	break;
	}
	return ret;
	}
	EXPORT_SYMBOL(rdma_resolve_ip);

	void rdma_addr_cancel(struct rdma_dev_addr *addr)
	{
	struct addr_req req, temp_req;

	mutex_lock(&lock);
	list_for_each_entry_safe(req, temp_req, &req_list, list) {
	if (req->addr == addr) {
	req->status = -ECANCELED;
	req->timeout = jiffies;
	list_move(&req->list, &req_list);
	set_timeout(req->timeout);
	break;
	}
	}
	mutex_unlock(&lock);
	}
	EXPORT_SYMBOL(rdma_addr_cancel);

	static int netevent_callback(struct notifier_block *self, unsigned long event,
	void *ctx)
	{
	if (event == NETEVENT_NEIGH_UPDATE) {
	struct neighbour *neigh = ctx;

	if (neigh->nud_state & NUD_VALID) {
	set_timeout(jiffies);
	}
	}
	return 0;
	}

	static struct notifier_block nb = {
	.notifier_call = netevent_callback
	};

	static int addr_init(void)
	{
	addr_wq = create_singlethread_workqueue("ib_addr");
	if (!addr_wq)
	return -ENOMEM;

	register_netevent_notifier(&nb);
	return 0;
	}

	static void addr_cleanup(void)
	{
	unregister_netevent_notifier(&nb);
	destroy_workqueue(addr_wq);
	}

	module_init(addr_init);
	module_exit(addr_cleanup);