net/tipc/eth_media.c - kernel/omap - Git at Google

 /*
  * net/tipc/eth_media.c: Ethernet bearer support for TIPC
  *
  * Copyright (c) 2001-2007, Ericsson AB
  * Copyright (c) 2005-2008, 2011, Wind River Systems
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. Neither the names of the copyright holders nor the names of its
  *    contributors may be used to endorse or promote products derived from
  *    this software without specific prior written permission.
  *
  * Alternatively, this software may be distributed under the terms of the
  * GNU General Public License ("GPL") version 2 as published by the Free
  * Software Foundation.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  */

 #include "core.h"
 #include "bearer.h"

 #define MAX_ETH_BEARERS		MAX_BEARERS

 #define ETH_ADDR_OFFSET	4	/* message header offset of MAC address */

 /**
  * struct eth_bearer - Ethernet bearer data structure
  * @bearer: ptr to associated "generic" bearer structure
  * @dev: ptr to associated Ethernet network device
  * @tipc_packet_type: used in binding TIPC to Ethernet driver
  * @setup: work item used when enabling bearer
  * @cleanup: work item used when disabling bearer
  */
 struct eth_bearer {
 	struct tipc_bearer *bearer;
 	struct net_device *dev;
 	struct packet_type tipc_packet_type;
 	struct work_struct setup;
 	struct work_struct cleanup;
 };

 static struct tipc_media eth_media_info;
 static struct eth_bearer eth_bearers[MAX_ETH_BEARERS];
 static int eth_started;

 static int recv_notification(struct notifier_block *nb, unsigned long evt,
 			      void *dv);
 /*
  * Network device notifier info
  */
 static struct notifier_block notifier = {
 	.notifier_call	= recv_notification,
 	.priority	= 0
 };

 /**
  * eth_media_addr_set - initialize Ethernet media address structure
  *
  * Media-dependent "value" field stores MAC address in first 6 bytes
  * and zeroes out the remaining bytes.
  */
 static void eth_media_addr_set(const struct tipc_bearer *tb_ptr,
 			       struct tipc_media_addr *a, char *mac)
 {
 	memcpy(a->value, mac, ETH_ALEN);
 	memset(a->value + ETH_ALEN, 0, sizeof(a->value) - ETH_ALEN);
 	a->media_id = TIPC_MEDIA_TYPE_ETH;
 	a->broadcast = !memcmp(mac, tb_ptr->bcast_addr.value, ETH_ALEN);
 }

 /**
  * send_msg - send a TIPC message out over an Ethernet interface
  */
 static int send_msg(struct sk_buff *buf, struct tipc_bearer *tb_ptr,
 		    struct tipc_media_addr *dest)
 {
 	struct sk_buff *clone;
 	struct net_device *dev;
 	int delta;

 	clone = skb_clone(buf, GFP_ATOMIC);
 	if (!clone)
 		return 0;

 	dev = ((struct eth_bearer *)(tb_ptr->usr_handle))->dev;
 	delta = dev->hard_header_len - skb_headroom(buf);

 	if ((delta > 0) &&
 	    pskb_expand_head(clone, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) {
 		kfree_skb(clone);
 		return 0;
 	}

 	skb_reset_network_header(clone);
 	clone->dev = dev;
 	clone->protocol = htons(ETH_P_TIPC);
 	dev_hard_header(clone, dev, ETH_P_TIPC, dest->value,
 			dev->dev_addr, clone->len);
 	dev_queue_xmit(clone);
 	return 0;
 }

 /**
  * recv_msg - handle incoming TIPC message from an Ethernet interface
  *
  * Accept only packets explicitly sent to this node, or broadcast packets;
  * ignores packets sent using Ethernet multicast, and traffic sent to other
  * nodes (which can happen if interface is running in promiscuous mode).
  */
 static int recv_msg(struct sk_buff *buf, struct net_device *dev,
 		    struct packet_type *pt, struct net_device *orig_dev)
 {
 	struct eth_bearer *eb_ptr = (struct eth_bearer *)pt->af_packet_priv;

 	if (!net_eq(dev_net(dev), &init_net)) {
 		kfree_skb(buf);
 		return 0;
 	}

 	if (likely(eb_ptr->bearer)) {
 		if (likely(buf->pkt_type <= PACKET_BROADCAST)) {
 			buf->next = NULL;
 			tipc_recv_msg(buf, eb_ptr->bearer);
 			return 0;
 		}
 	}
 	kfree_skb(buf);
 	return 0;
 }

 /**
  * setup_bearer - setup association between Ethernet bearer and interface
  */
 static void setup_bearer(struct work_struct *work)
 {
 	struct eth_bearer *eb_ptr =
 		container_of(work, struct eth_bearer, setup);

 	dev_add_pack(&eb_ptr->tipc_packet_type);
 }

 /**
  * enable_bearer - attach TIPC bearer to an Ethernet interface
  */
 static int enable_bearer(struct tipc_bearer *tb_ptr)
 {
 	struct net_device *dev = NULL;
 	struct net_device *pdev = NULL;
 	struct eth_bearer *eb_ptr = &eth_bearers[0];
 	struct eth_bearer *stop = &eth_bearers[MAX_ETH_BEARERS];
 	char *driver_name = strchr((const char *)tb_ptr->name, ':') + 1;
 	int pending_dev = 0;

 	/* Find unused Ethernet bearer structure */
 	while (eb_ptr->dev) {
 		if (!eb_ptr->bearer)
 			pending_dev++;
 		if (++eb_ptr == stop)
 			return pending_dev ? -EAGAIN : -EDQUOT;
 	}

 	/* Find device with specified name */
 	read_lock(&dev_base_lock);
 	for_each_netdev(&init_net, pdev) {
 		if (!strncmp(pdev->name, driver_name, IFNAMSIZ)) {
 			dev = pdev;
 			dev_hold(dev);
 			break;
 		}
 	}
 	read_unlock(&dev_base_lock);
 	if (!dev)
 		return -ENODEV;

 	/* Create Ethernet bearer for device */
 	eb_ptr->dev = dev;
 	eb_ptr->tipc_packet_type.type = htons(ETH_P_TIPC);
 	eb_ptr->tipc_packet_type.dev = dev;
 	eb_ptr->tipc_packet_type.func = recv_msg;
 	eb_ptr->tipc_packet_type.af_packet_priv = eb_ptr;
 	INIT_LIST_HEAD(&(eb_ptr->tipc_packet_type.list));
 	INIT_WORK(&eb_ptr->setup, setup_bearer);
 	schedule_work(&eb_ptr->setup);

 	/* Associate TIPC bearer with Ethernet bearer */
 	eb_ptr->bearer = tb_ptr;
 	tb_ptr->usr_handle = (void *)eb_ptr;
 	memset(tb_ptr->bcast_addr.value, 0, sizeof(tb_ptr->bcast_addr.value));
 	memcpy(tb_ptr->bcast_addr.value, dev->broadcast, ETH_ALEN);
 	tb_ptr->bcast_addr.media_id = TIPC_MEDIA_TYPE_ETH;
 	tb_ptr->bcast_addr.broadcast = 1;
 	tb_ptr->mtu = dev->mtu;
 	tb_ptr->blocked = 0;
 	eth_media_addr_set(tb_ptr, &tb_ptr->addr, (char *)dev->dev_addr);
 	return 0;
 }

 /**
  * cleanup_bearer - break association between Ethernet bearer and interface
  *
  * This routine must be invoked from a work queue because it can sleep.
  */
 static void cleanup_bearer(struct work_struct *work)
 {
 	struct eth_bearer *eb_ptr =
 		container_of(work, struct eth_bearer, cleanup);

 	dev_remove_pack(&eb_ptr->tipc_packet_type);
 	dev_put(eb_ptr->dev);
 	eb_ptr->dev = NULL;
 }

 /**
  * disable_bearer - detach TIPC bearer from an Ethernet interface
  *
  * Mark Ethernet bearer as inactive so that incoming buffers are thrown away,
  * then get worker thread to complete bearer cleanup.  (Can't do cleanup
  * here because cleanup code needs to sleep and caller holds spinlocks.)
  */
 static void disable_bearer(struct tipc_bearer *tb_ptr)
 {
 	struct eth_bearer *eb_ptr = (struct eth_bearer *)tb_ptr->usr_handle;

 	eb_ptr->bearer = NULL;
 	INIT_WORK(&eb_ptr->cleanup, cleanup_bearer);
 	schedule_work(&eb_ptr->cleanup);
 }

 /**
  * recv_notification - handle device updates from OS
  *
  * Change the state of the Ethernet bearer (if any) associated with the
  * specified device.
  */
 static int recv_notification(struct notifier_block *nb, unsigned long evt,
 			     void *dv)
 {
 	struct net_device *dev = (struct net_device *)dv;
 	struct eth_bearer *eb_ptr = &eth_bearers[0];
 	struct eth_bearer *stop = &eth_bearers[MAX_ETH_BEARERS];

 	if (!net_eq(dev_net(dev), &init_net))
 		return NOTIFY_DONE;

 	while ((eb_ptr->dev != dev)) {
 		if (++eb_ptr == stop)
 			return NOTIFY_DONE;	/* couldn't find device */
 	}
 	if (!eb_ptr->bearer)
 		return NOTIFY_DONE;		/* bearer had been disabled */

 	eb_ptr->bearer->mtu = dev->mtu;

 	switch (evt) {
 	case NETDEV_CHANGE:
 		if (netif_carrier_ok(dev))
 			tipc_continue(eb_ptr->bearer);
 		else
 			tipc_block_bearer(eb_ptr->bearer->name);
 		break;
 	case NETDEV_UP:
 		tipc_continue(eb_ptr->bearer);
 		break;
 	case NETDEV_DOWN:
 		tipc_block_bearer(eb_ptr->bearer->name);
 		break;
 	case NETDEV_CHANGEMTU:
 	case NETDEV_CHANGEADDR:
 		tipc_block_bearer(eb_ptr->bearer->name);
 		tipc_continue(eb_ptr->bearer);
 		break;
 	case NETDEV_UNREGISTER:
 	case NETDEV_CHANGENAME:
 		tipc_disable_bearer(eb_ptr->bearer->name);
 		break;
 	}
 	return NOTIFY_OK;
 }

 /**
  * eth_addr2str - convert Ethernet address to string
  */
 static int eth_addr2str(struct tipc_media_addr *a, char *str_buf, int str_size)
 {
 	if (str_size < 18)	/* 18 = strlen("aa:bb:cc:dd:ee:ff\0") */
 		return 1;

 	sprintf(str_buf, "%pM", a->value);
 	return 0;
 }

 /**
  * eth_str2addr - convert Ethernet address format to message header format
  */
 static int eth_addr2msg(struct tipc_media_addr *a, char *msg_area)
 {
 	memset(msg_area, 0, TIPC_MEDIA_ADDR_SIZE);
 	msg_area[TIPC_MEDIA_TYPE_OFFSET] = TIPC_MEDIA_TYPE_ETH;
 	memcpy(msg_area + ETH_ADDR_OFFSET, a->value, ETH_ALEN);
 	return 0;
 }

 /**
  * eth_str2addr - convert message header address format to Ethernet format
  */
 static int eth_msg2addr(const struct tipc_bearer *tb_ptr,
 			struct tipc_media_addr *a, char *msg_area)
 {
 	if (msg_area[TIPC_MEDIA_TYPE_OFFSET] != TIPC_MEDIA_TYPE_ETH)
 		return 1;

 	eth_media_addr_set(tb_ptr, a, msg_area + ETH_ADDR_OFFSET);
 	return 0;
 }

 /*
  * Ethernet media registration info
  */
 static struct tipc_media eth_media_info = {
 	.send_msg	= send_msg,
 	.enable_bearer	= enable_bearer,
 	.disable_bearer	= disable_bearer,
 	.addr2str	= eth_addr2str,
 	.addr2msg	= eth_addr2msg,
 	.msg2addr	= eth_msg2addr,
 	.priority	= TIPC_DEF_LINK_PRI,
 	.tolerance	= TIPC_DEF_LINK_TOL,
 	.window		= TIPC_DEF_LINK_WIN,
 	.type_id	= TIPC_MEDIA_TYPE_ETH,
 	.name		= "eth"
 };

 /**
  * tipc_eth_media_start - activate Ethernet bearer support
  *
  * Register Ethernet media type with TIPC bearer code.  Also register
  * with OS for notifications about device state changes.
  */
 int tipc_eth_media_start(void)
 {
 	int res;

 	if (eth_started)
 		return -EINVAL;

 	res = tipc_register_media(&eth_media_info);
 	if (res)
 		return res;

 	res = register_netdevice_notifier(&notifier);
 	if (!res)
 		eth_started = 1;
 	return res;
 }

 /**
  * tipc_eth_media_stop - deactivate Ethernet bearer support
  */
 void tipc_eth_media_stop(void)
 {
 	if (!eth_started)
 		return;

 	flush_scheduled_work();
 	unregister_netdevice_notifier(&notifier);
 	eth_started = 0;
 }
	/*
	* net/tipc/eth_media.c: Ethernet bearer support for TIPC
	*
	* Copyright (c) 2001-2007, Ericsson AB
	* Copyright (c) 2005-2008, 2011, Wind River Systems
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are met:
	*
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	* 3. Neither the names of the copyright holders nor the names of its
	* contributors may be used to endorse or promote products derived from
	* this software without specific prior written permission.
	*
	* Alternatively, this software may be distributed under the terms of the
	* GNU General Public License ("GPL") version 2 as published by the Free
	* Software Foundation.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
	* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
	* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
	* POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "core.h"
	#include "bearer.h"

	#define MAX_ETH_BEARERS MAX_BEARERS

	#define ETH_ADDR_OFFSET 4 /* message header offset of MAC address */

	/**
	* struct eth_bearer - Ethernet bearer data structure
	* @bearer: ptr to associated "generic" bearer structure
	* @dev: ptr to associated Ethernet network device
	* @tipc_packet_type: used in binding TIPC to Ethernet driver
	* @setup: work item used when enabling bearer
	* @cleanup: work item used when disabling bearer
	*/
	struct eth_bearer {
	struct tipc_bearer *bearer;
	struct net_device *dev;
	struct packet_type tipc_packet_type;
	struct work_struct setup;
	struct work_struct cleanup;
	};

	static struct tipc_media eth_media_info;
	static struct eth_bearer eth_bearers[MAX_ETH_BEARERS];
	static int eth_started;

	static int recv_notification(struct notifier_block *nb, unsigned long evt,
	void *dv);
	/*
	* Network device notifier info
	*/
	static struct notifier_block notifier = {
	.notifier_call = recv_notification,
	.priority = 0
	};

	/**
	* eth_media_addr_set - initialize Ethernet media address structure
	*
	* Media-dependent "value" field stores MAC address in first 6 bytes
	* and zeroes out the remaining bytes.
	*/
	static void eth_media_addr_set(const struct tipc_bearer *tb_ptr,
	struct tipc_media_addr a, char mac)
	{
	memcpy(a->value, mac, ETH_ALEN);
	memset(a->value + ETH_ALEN, 0, sizeof(a->value) - ETH_ALEN);
	a->media_id = TIPC_MEDIA_TYPE_ETH;
	a->broadcast = !memcmp(mac, tb_ptr->bcast_addr.value, ETH_ALEN);
	}

	/**
	* send_msg - send a TIPC message out over an Ethernet interface
	*/
	static int send_msg(struct sk_buff buf, struct tipc_bearer tb_ptr,
	struct tipc_media_addr *dest)
	{
	struct sk_buff *clone;
	struct net_device *dev;
	int delta;

	clone = skb_clone(buf, GFP_ATOMIC);
	if (!clone)
	return 0;

	dev = ((struct eth_bearer *)(tb_ptr->usr_handle))->dev;
	delta = dev->hard_header_len - skb_headroom(buf);

	if ((delta > 0) &&
	pskb_expand_head(clone, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) {
	kfree_skb(clone);
	return 0;
	}

	skb_reset_network_header(clone);
	clone->dev = dev;
	clone->protocol = htons(ETH_P_TIPC);
	dev_hard_header(clone, dev, ETH_P_TIPC, dest->value,
	dev->dev_addr, clone->len);
	dev_queue_xmit(clone);
	return 0;
	}

	/**
	* recv_msg - handle incoming TIPC message from an Ethernet interface
	*
	* Accept only packets explicitly sent to this node, or broadcast packets;
	* ignores packets sent using Ethernet multicast, and traffic sent to other
	* nodes (which can happen if interface is running in promiscuous mode).
	*/
	static int recv_msg(struct sk_buff buf, struct net_device dev,
	struct packet_type pt, struct net_device orig_dev)
	{
	struct eth_bearer eb_ptr = (struct eth_bearer )pt->af_packet_priv;

	if (!net_eq(dev_net(dev), &init_net)) {
	kfree_skb(buf);
	return 0;
	}

	if (likely(eb_ptr->bearer)) {
	if (likely(buf->pkt_type <= PACKET_BROADCAST)) {
	buf->next = NULL;
	tipc_recv_msg(buf, eb_ptr->bearer);
	return 0;
	}
	}
	kfree_skb(buf);
	return 0;
	}

	/**
	* setup_bearer - setup association between Ethernet bearer and interface
	*/
	static void setup_bearer(struct work_struct *work)
	{
	struct eth_bearer *eb_ptr =
	container_of(work, struct eth_bearer, setup);

	dev_add_pack(&eb_ptr->tipc_packet_type);
	}

	/**
	* enable_bearer - attach TIPC bearer to an Ethernet interface
	*/
	static int enable_bearer(struct tipc_bearer *tb_ptr)
	{
	struct net_device *dev = NULL;
	struct net_device *pdev = NULL;
	struct eth_bearer *eb_ptr = &eth_bearers[0];
	struct eth_bearer *stop = &eth_bearers[MAX_ETH_BEARERS];
	char driver_name = strchr((const char )tb_ptr->name, ':') + 1;
	int pending_dev = 0;

	/* Find unused Ethernet bearer structure */
	while (eb_ptr->dev) {
	if (!eb_ptr->bearer)
	pending_dev++;
	if (++eb_ptr == stop)
	return pending_dev ? -EAGAIN : -EDQUOT;
	}

	/* Find device with specified name */
	read_lock(&dev_base_lock);
	for_each_netdev(&init_net, pdev) {
	if (!strncmp(pdev->name, driver_name, IFNAMSIZ)) {
	dev = pdev;
	dev_hold(dev);
	break;
	}
	}
	read_unlock(&dev_base_lock);
	if (!dev)
	return -ENODEV;

	/* Create Ethernet bearer for device */
	eb_ptr->dev = dev;
	eb_ptr->tipc_packet_type.type = htons(ETH_P_TIPC);
	eb_ptr->tipc_packet_type.dev = dev;
	eb_ptr->tipc_packet_type.func = recv_msg;
	eb_ptr->tipc_packet_type.af_packet_priv = eb_ptr;
	INIT_LIST_HEAD(&(eb_ptr->tipc_packet_type.list));
	INIT_WORK(&eb_ptr->setup, setup_bearer);
	schedule_work(&eb_ptr->setup);

	/* Associate TIPC bearer with Ethernet bearer */
	eb_ptr->bearer = tb_ptr;
	tb_ptr->usr_handle = (void *)eb_ptr;
	memset(tb_ptr->bcast_addr.value, 0, sizeof(tb_ptr->bcast_addr.value));
	memcpy(tb_ptr->bcast_addr.value, dev->broadcast, ETH_ALEN);
	tb_ptr->bcast_addr.media_id = TIPC_MEDIA_TYPE_ETH;
	tb_ptr->bcast_addr.broadcast = 1;
	tb_ptr->mtu = dev->mtu;
	tb_ptr->blocked = 0;
	eth_media_addr_set(tb_ptr, &tb_ptr->addr, (char *)dev->dev_addr);
	return 0;
	}

	/**
	* cleanup_bearer - break association between Ethernet bearer and interface
	*
	* This routine must be invoked from a work queue because it can sleep.
	*/
	static void cleanup_bearer(struct work_struct *work)
	{
	struct eth_bearer *eb_ptr =
	container_of(work, struct eth_bearer, cleanup);

	dev_remove_pack(&eb_ptr->tipc_packet_type);
	dev_put(eb_ptr->dev);
	eb_ptr->dev = NULL;
	}

	/**
	* disable_bearer - detach TIPC bearer from an Ethernet interface
	*
	* Mark Ethernet bearer as inactive so that incoming buffers are thrown away,
	* then get worker thread to complete bearer cleanup. (Can't do cleanup
	* here because cleanup code needs to sleep and caller holds spinlocks.)
	*/
	static void disable_bearer(struct tipc_bearer *tb_ptr)
	{
	struct eth_bearer eb_ptr = (struct eth_bearer )tb_ptr->usr_handle;

	eb_ptr->bearer = NULL;
	INIT_WORK(&eb_ptr->cleanup, cleanup_bearer);
	schedule_work(&eb_ptr->cleanup);
	}

	/**
	* recv_notification - handle device updates from OS
	*
	* Change the state of the Ethernet bearer (if any) associated with the
	* specified device.
	*/
	static int recv_notification(struct notifier_block *nb, unsigned long evt,
	void *dv)
	{
	struct net_device dev = (struct net_device )dv;
	struct eth_bearer *eb_ptr = &eth_bearers[0];
	struct eth_bearer *stop = &eth_bearers[MAX_ETH_BEARERS];

	if (!net_eq(dev_net(dev), &init_net))
	return NOTIFY_DONE;

	while ((eb_ptr->dev != dev)) {
	if (++eb_ptr == stop)
	return NOTIFY_DONE; /* couldn't find device */
	}
	if (!eb_ptr->bearer)
	return NOTIFY_DONE; /* bearer had been disabled */

	eb_ptr->bearer->mtu = dev->mtu;

	switch (evt) {
	case NETDEV_CHANGE:
	if (netif_carrier_ok(dev))
	tipc_continue(eb_ptr->bearer);
	else
	tipc_block_bearer(eb_ptr->bearer->name);
	break;
	case NETDEV_UP:
	tipc_continue(eb_ptr->bearer);
	break;
	case NETDEV_DOWN:
	tipc_block_bearer(eb_ptr->bearer->name);
	break;
	case NETDEV_CHANGEMTU:
	case NETDEV_CHANGEADDR:
	tipc_block_bearer(eb_ptr->bearer->name);
	tipc_continue(eb_ptr->bearer);
	break;
	case NETDEV_UNREGISTER:
	case NETDEV_CHANGENAME:
	tipc_disable_bearer(eb_ptr->bearer->name);
	break;
	}
	return NOTIFY_OK;
	}

	/**
	* eth_addr2str - convert Ethernet address to string
	*/
	static int eth_addr2str(struct tipc_media_addr a, char str_buf, int str_size)
	{
	if (str_size < 18) /* 18 = strlen("aa:bb:cc:dd:ee:ff\0") */
	return 1;

	sprintf(str_buf, "%pM", a->value);
	return 0;
	}

	/**
	* eth_str2addr - convert Ethernet address format to message header format
	*/
	static int eth_addr2msg(struct tipc_media_addr a, char msg_area)
	{
	memset(msg_area, 0, TIPC_MEDIA_ADDR_SIZE);
	msg_area[TIPC_MEDIA_TYPE_OFFSET] = TIPC_MEDIA_TYPE_ETH;
	memcpy(msg_area + ETH_ADDR_OFFSET, a->value, ETH_ALEN);
	return 0;
	}

	/**
	* eth_str2addr - convert message header address format to Ethernet format
	*/
	static int eth_msg2addr(const struct tipc_bearer *tb_ptr,
	struct tipc_media_addr a, char msg_area)
	{
	if (msg_area[TIPC_MEDIA_TYPE_OFFSET] != TIPC_MEDIA_TYPE_ETH)
	return 1;

	eth_media_addr_set(tb_ptr, a, msg_area + ETH_ADDR_OFFSET);
	return 0;
	}

	/*
	* Ethernet media registration info
	*/
	static struct tipc_media eth_media_info = {
	.send_msg = send_msg,
	.enable_bearer = enable_bearer,
	.disable_bearer = disable_bearer,
	.addr2str = eth_addr2str,
	.addr2msg = eth_addr2msg,
	.msg2addr = eth_msg2addr,
	.priority = TIPC_DEF_LINK_PRI,
	.tolerance = TIPC_DEF_LINK_TOL,
	.window = TIPC_DEF_LINK_WIN,
	.type_id = TIPC_MEDIA_TYPE_ETH,
	.name = "eth"
	};

	/**
	* tipc_eth_media_start - activate Ethernet bearer support
	*
	* Register Ethernet media type with TIPC bearer code. Also register
	* with OS for notifications about device state changes.
	*/
	int tipc_eth_media_start(void)
	{
	int res;

	if (eth_started)
	return -EINVAL;

	res = tipc_register_media(&eth_media_info);
	if (res)
	return res;

	res = register_netdevice_notifier(&notifier);
	if (!res)
	eth_started = 1;
	return res;
	}

	/**
	* tipc_eth_media_stop - deactivate Ethernet bearer support
	*/
	void tipc_eth_media_stop(void)
	{
	if (!eth_started)
	return;

	flush_scheduled_work();
	unregister_netdevice_notifier(&notifier);
	eth_started = 0;
	}