net/lapb/lapb_iface.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *	LAPB release 002
  *
  *	This code REQUIRES 2.1.15 or higher/ NET3.038
  *
  *	History
  *	LAPB 001	Jonathan Naylor	Started Coding
  *	LAPB 002	Jonathan Naylor	New timer architecture.
  *	2000-10-29	Henner Eisen	lapb_data_indication() return status.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/types.h>
 #include <linux/socket.h>
 #include <linux/in.h>
 #include <linux/kernel.h>
 #include <linux/jiffies.h>
 #include <linux/timer.h>
 #include <linux/string.h>
 #include <linux/sockios.h>
 #include <linux/net.h>
 #include <linux/inet.h>
 #include <linux/if_arp.h>
 #include <linux/skbuff.h>
 #include <linux/slab.h>
 #include <net/sock.h>
 #include <linux/uaccess.h>
 #include <linux/fcntl.h>
 #include <linux/mm.h>
 #include <linux/interrupt.h>
 #include <linux/stat.h>
 #include <linux/init.h>
 #include <net/lapb.h>

 static LIST_HEAD(lapb_list);
 static DEFINE_RWLOCK(lapb_list_lock);

 /*
  *	Free an allocated lapb control block.
  */
 static void lapb_free_cb(struct lapb_cb *lapb)
 {
 	kfree(lapb);
 }

 static __inline__ void lapb_hold(struct lapb_cb *lapb)
 {
 	refcount_inc(&lapb->refcnt);
 }

 static __inline__ void lapb_put(struct lapb_cb *lapb)
 {
 	if (refcount_dec_and_test(&lapb->refcnt))
 		lapb_free_cb(lapb);
 }

 /*
  *	Socket removal during an interrupt is now safe.
  */
 static void __lapb_remove_cb(struct lapb_cb *lapb)
 {
 	if (lapb->node.next) {
 		list_del(&lapb->node);
 		lapb_put(lapb);
 	}
 }

 /*
  *	Add a socket to the bound sockets list.
  */
 static void __lapb_insert_cb(struct lapb_cb *lapb)
 {
 	list_add(&lapb->node, &lapb_list);
 	lapb_hold(lapb);
 }

 static struct lapb_cb *__lapb_devtostruct(struct net_device *dev)
 {
 	struct list_head *entry;
 	struct lapb_cb *lapb, *use = NULL;

 	list_for_each(entry, &lapb_list) {
 		lapb = list_entry(entry, struct lapb_cb, node);
 		if (lapb->dev == dev) {
 			use = lapb;
 			break;
 		}
 	}

 	if (use)
 		lapb_hold(use);

 	return use;
 }

 static struct lapb_cb *lapb_devtostruct(struct net_device *dev)
 {
 	struct lapb_cb *rc;

 	read_lock_bh(&lapb_list_lock);
 	rc = __lapb_devtostruct(dev);
 	read_unlock_bh(&lapb_list_lock);

 	return rc;
 }
 /*
  *	Create an empty LAPB control block.
  */
 static struct lapb_cb *lapb_create_cb(void)
 {
 	struct lapb_cb *lapb = kzalloc(sizeof(*lapb), GFP_ATOMIC);

 	if (!lapb)
 		goto out;

 	skb_queue_head_init(&lapb->write_queue);
 	skb_queue_head_init(&lapb->ack_queue);

 	timer_setup(&lapb->t1timer, NULL, 0);
 	timer_setup(&lapb->t2timer, NULL, 0);

 	lapb->t1      = LAPB_DEFAULT_T1;
 	lapb->t2      = LAPB_DEFAULT_T2;
 	lapb->n2      = LAPB_DEFAULT_N2;
 	lapb->mode    = LAPB_DEFAULT_MODE;
 	lapb->window  = LAPB_DEFAULT_WINDOW;
 	lapb->state   = LAPB_STATE_0;
 	refcount_set(&lapb->refcnt, 1);
 out:
 	return lapb;
 }

 int lapb_register(struct net_device *dev,
 		  const struct lapb_register_struct *callbacks)
 {
 	struct lapb_cb *lapb;
 	int rc = LAPB_BADTOKEN;

 	write_lock_bh(&lapb_list_lock);

 	lapb = __lapb_devtostruct(dev);
 	if (lapb) {
 		lapb_put(lapb);
 		goto out;
 	}

 	lapb = lapb_create_cb();
 	rc = LAPB_NOMEM;
 	if (!lapb)
 		goto out;

 	lapb->dev       = dev;
 	lapb->callbacks = callbacks;

 	__lapb_insert_cb(lapb);

 	lapb_start_t1timer(lapb);

 	rc = LAPB_OK;
 out:
 	write_unlock_bh(&lapb_list_lock);
 	return rc;
 }
 EXPORT_SYMBOL(lapb_register);

 int lapb_unregister(struct net_device *dev)
 {
 	struct lapb_cb *lapb;
 	int rc = LAPB_BADTOKEN;

 	write_lock_bh(&lapb_list_lock);
 	lapb = __lapb_devtostruct(dev);
 	if (!lapb)
 		goto out;
 	lapb_put(lapb);

 	lapb_stop_t1timer(lapb);
 	lapb_stop_t2timer(lapb);

 	lapb_clear_queues(lapb);

 	__lapb_remove_cb(lapb);

 	lapb_put(lapb);
 	rc = LAPB_OK;
 out:
 	write_unlock_bh(&lapb_list_lock);
 	return rc;
 }
 EXPORT_SYMBOL(lapb_unregister);

 int lapb_getparms(struct net_device *dev, struct lapb_parms_struct *parms)
 {
 	int rc = LAPB_BADTOKEN;
 	struct lapb_cb *lapb = lapb_devtostruct(dev);

 	if (!lapb)
 		goto out;

 	parms->t1      = lapb->t1 / HZ;
 	parms->t2      = lapb->t2 / HZ;
 	parms->n2      = lapb->n2;
 	parms->n2count = lapb->n2count;
 	parms->state   = lapb->state;
 	parms->window  = lapb->window;
 	parms->mode    = lapb->mode;

 	if (!timer_pending(&lapb->t1timer))
 		parms->t1timer = 0;
 	else
 		parms->t1timer = (lapb->t1timer.expires - jiffies) / HZ;

 	if (!timer_pending(&lapb->t2timer))
 		parms->t2timer = 0;
 	else
 		parms->t2timer = (lapb->t2timer.expires - jiffies) / HZ;

 	lapb_put(lapb);
 	rc = LAPB_OK;
 out:
 	return rc;
 }
 EXPORT_SYMBOL(lapb_getparms);

 int lapb_setparms(struct net_device *dev, struct lapb_parms_struct *parms)
 {
 	int rc = LAPB_BADTOKEN;
 	struct lapb_cb *lapb = lapb_devtostruct(dev);

 	if (!lapb)
 		goto out;

 	rc = LAPB_INVALUE;
 	if (parms->t1 < 1 || parms->t2 < 1 || parms->n2 < 1)
 		goto out_put;

 	if (lapb->state == LAPB_STATE_0) {
 		if (parms->mode & LAPB_EXTENDED) {
 			if (parms->window < 1 || parms->window > 127)
 				goto out_put;
 		} else {
 			if (parms->window < 1 || parms->window > 7)
 				goto out_put;
 		}
 		lapb->mode    = parms->mode;
 		lapb->window  = parms->window;
 	}

 	lapb->t1    = parms->t1 * HZ;
 	lapb->t2    = parms->t2 * HZ;
 	lapb->n2    = parms->n2;

 	rc = LAPB_OK;
 out_put:
 	lapb_put(lapb);
 out:
 	return rc;
 }
 EXPORT_SYMBOL(lapb_setparms);

 int lapb_connect_request(struct net_device *dev)
 {
 	struct lapb_cb *lapb = lapb_devtostruct(dev);
 	int rc = LAPB_BADTOKEN;

 	if (!lapb)
 		goto out;

 	rc = LAPB_OK;
 	if (lapb->state == LAPB_STATE_1)
 		goto out_put;

 	rc = LAPB_CONNECTED;
 	if (lapb->state == LAPB_STATE_3 || lapb->state == LAPB_STATE_4)
 		goto out_put;

 	lapb_establish_data_link(lapb);

 	lapb_dbg(0, "(%p) S0 -> S1\n", lapb->dev);
 	lapb->state = LAPB_STATE_1;

 	rc = LAPB_OK;
 out_put:
 	lapb_put(lapb);
 out:
 	return rc;
 }
 EXPORT_SYMBOL(lapb_connect_request);

 int lapb_disconnect_request(struct net_device *dev)
 {
 	struct lapb_cb *lapb = lapb_devtostruct(dev);
 	int rc = LAPB_BADTOKEN;

 	if (!lapb)
 		goto out;

 	switch (lapb->state) {
 	case LAPB_STATE_0:
 		rc = LAPB_NOTCONNECTED;
 		goto out_put;

 	case LAPB_STATE_1:
 		lapb_dbg(1, "(%p) S1 TX DISC(1)\n", lapb->dev);
 		lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev);
 		lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
 		lapb->state = LAPB_STATE_0;
 		lapb_start_t1timer(lapb);
 		rc = LAPB_NOTCONNECTED;
 		goto out_put;

 	case LAPB_STATE_2:
 		rc = LAPB_OK;
 		goto out_put;
 	}

 	lapb_clear_queues(lapb);
 	lapb->n2count = 0;
 	lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
 	lapb_start_t1timer(lapb);
 	lapb_stop_t2timer(lapb);
 	lapb->state = LAPB_STATE_2;

 	lapb_dbg(1, "(%p) S3 DISC(1)\n", lapb->dev);
 	lapb_dbg(0, "(%p) S3 -> S2\n", lapb->dev);

 	rc = LAPB_OK;
 out_put:
 	lapb_put(lapb);
 out:
 	return rc;
 }
 EXPORT_SYMBOL(lapb_disconnect_request);

 int lapb_data_request(struct net_device *dev, struct sk_buff *skb)
 {
 	struct lapb_cb *lapb = lapb_devtostruct(dev);
 	int rc = LAPB_BADTOKEN;

 	if (!lapb)
 		goto out;

 	rc = LAPB_NOTCONNECTED;
 	if (lapb->state != LAPB_STATE_3 && lapb->state != LAPB_STATE_4)
 		goto out_put;

 	skb_queue_tail(&lapb->write_queue, skb);
 	lapb_kick(lapb);
 	rc = LAPB_OK;
 out_put:
 	lapb_put(lapb);
 out:
 	return rc;
 }
 EXPORT_SYMBOL(lapb_data_request);

 int lapb_data_received(struct net_device *dev, struct sk_buff *skb)
 {
 	struct lapb_cb *lapb = lapb_devtostruct(dev);
 	int rc = LAPB_BADTOKEN;

 	if (lapb) {
 		lapb_data_input(lapb, skb);
 		lapb_put(lapb);
 		rc = LAPB_OK;
 	}

 	return rc;
 }
 EXPORT_SYMBOL(lapb_data_received);

 void lapb_connect_confirmation(struct lapb_cb *lapb, int reason)
 {
 	if (lapb->callbacks->connect_confirmation)
 		lapb->callbacks->connect_confirmation(lapb->dev, reason);
 }

 void lapb_connect_indication(struct lapb_cb *lapb, int reason)
 {
 	if (lapb->callbacks->connect_indication)
 		lapb->callbacks->connect_indication(lapb->dev, reason);
 }

 void lapb_disconnect_confirmation(struct lapb_cb *lapb, int reason)
 {
 	if (lapb->callbacks->disconnect_confirmation)
 		lapb->callbacks->disconnect_confirmation(lapb->dev, reason);
 }

 void lapb_disconnect_indication(struct lapb_cb *lapb, int reason)
 {
 	if (lapb->callbacks->disconnect_indication)
 		lapb->callbacks->disconnect_indication(lapb->dev, reason);
 }

 int lapb_data_indication(struct lapb_cb *lapb, struct sk_buff *skb)
 {
 	if (lapb->callbacks->data_indication)
 		return lapb->callbacks->data_indication(lapb->dev, skb);

 	kfree_skb(skb);
 	return NET_RX_SUCCESS; /* For now; must be != NET_RX_DROP */
 }

 int lapb_data_transmit(struct lapb_cb *lapb, struct sk_buff *skb)
 {
 	int used = 0;

 	if (lapb->callbacks->data_transmit) {
 		lapb->callbacks->data_transmit(lapb->dev, skb);
 		used = 1;
 	}

 	return used;
 }

 /* Handle device status changes. */
 static int lapb_device_event(struct notifier_block *this, unsigned long event,
 			     void *ptr)
 {
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 	struct lapb_cb *lapb;

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

 	if (dev->type != ARPHRD_X25)
 		return NOTIFY_DONE;

 	lapb = lapb_devtostruct(dev);
 	if (!lapb)
 		return NOTIFY_DONE;

 	switch (event) {
 	case NETDEV_UP:
 		lapb_dbg(0, "(%p) Interface up: %s\n", dev, dev->name);

 		if (netif_carrier_ok(dev)) {
 			lapb_dbg(0, "(%p): Carrier is already up: %s\n", dev,
 				 dev->name);
 			if (lapb->mode & LAPB_DCE) {
 				lapb_start_t1timer(lapb);
 			} else {
 				if (lapb->state == LAPB_STATE_0) {
 					lapb->state = LAPB_STATE_1;
 					lapb_establish_data_link(lapb);
 				}
 			}
 		}
 		break;
 	case NETDEV_GOING_DOWN:
 		if (netif_carrier_ok(dev))
 			lapb_disconnect_request(dev);
 		break;
 	case NETDEV_DOWN:
 		lapb_dbg(0, "(%p) Interface down: %s\n", dev, dev->name);
 		lapb_dbg(0, "(%p) S%d -> S0\n", dev, lapb->state);
 		lapb_clear_queues(lapb);
 		lapb->state = LAPB_STATE_0;
 		lapb->n2count   = 0;
 		lapb_stop_t1timer(lapb);
 		lapb_stop_t2timer(lapb);
 		break;
 	case NETDEV_CHANGE:
 		if (netif_carrier_ok(dev)) {
 			lapb_dbg(0, "(%p): Carrier detected: %s\n", dev,
 				 dev->name);
 			if (lapb->mode & LAPB_DCE) {
 				lapb_start_t1timer(lapb);
 			} else {
 				if (lapb->state == LAPB_STATE_0) {
 					lapb->state = LAPB_STATE_1;
 					lapb_establish_data_link(lapb);
 				}
 			}
 		} else {
 			lapb_dbg(0, "(%p) Carrier lost: %s\n", dev, dev->name);
 			lapb_dbg(0, "(%p) S%d -> S0\n", dev, lapb->state);
 			lapb_clear_queues(lapb);
 			lapb->state = LAPB_STATE_0;
 			lapb->n2count   = 0;
 			lapb_stop_t1timer(lapb);
 			lapb_stop_t2timer(lapb);
 		}
 		break;
 	}

 	return NOTIFY_DONE;
 }

 static struct notifier_block lapb_dev_notifier = {
 	.notifier_call = lapb_device_event,
 };

 static int __init lapb_init(void)
 {
 	return register_netdevice_notifier(&lapb_dev_notifier);
 }

 static void __exit lapb_exit(void)
 {
 	WARN_ON(!list_empty(&lapb_list));

 	unregister_netdevice_notifier(&lapb_dev_notifier);
 }

 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
 MODULE_DESCRIPTION("The X.25 Link Access Procedure B link layer protocol");
 MODULE_LICENSE("GPL");

 module_init(lapb_init);
 module_exit(lapb_exit);
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* LAPB release 002
	*
	* This code REQUIRES 2.1.15 or higher/ NET3.038
	*
	* History
	* LAPB 001 Jonathan Naylor Started Coding
	* LAPB 002 Jonathan Naylor New timer architecture.
	* 2000-10-29 Henner Eisen lapb_data_indication() return status.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/module.h>
	#include <linux/errno.h>
	#include <linux/types.h>
	#include <linux/socket.h>
	#include <linux/in.h>
	#include <linux/kernel.h>
	#include <linux/jiffies.h>
	#include <linux/timer.h>
	#include <linux/string.h>
	#include <linux/sockios.h>
	#include <linux/net.h>
	#include <linux/inet.h>
	#include <linux/if_arp.h>
	#include <linux/skbuff.h>
	#include <linux/slab.h>
	#include <net/sock.h>
	#include <linux/uaccess.h>
	#include <linux/fcntl.h>
	#include <linux/mm.h>
	#include <linux/interrupt.h>
	#include <linux/stat.h>
	#include <linux/init.h>
	#include <net/lapb.h>

	static LIST_HEAD(lapb_list);
	static DEFINE_RWLOCK(lapb_list_lock);

	/*
	* Free an allocated lapb control block.
	*/
	static void lapb_free_cb(struct lapb_cb *lapb)
	{
	kfree(lapb);
	}

	static __inline__ void lapb_hold(struct lapb_cb *lapb)
	{
	refcount_inc(&lapb->refcnt);
	}

	static __inline__ void lapb_put(struct lapb_cb *lapb)
	{
	if (refcount_dec_and_test(&lapb->refcnt))
	lapb_free_cb(lapb);
	}

	/*
	* Socket removal during an interrupt is now safe.
	*/
	static void __lapb_remove_cb(struct lapb_cb *lapb)
	{
	if (lapb->node.next) {
	list_del(&lapb->node);
	lapb_put(lapb);
	}
	}

	/*
	* Add a socket to the bound sockets list.
	*/
	static void __lapb_insert_cb(struct lapb_cb *lapb)
	{
	list_add(&lapb->node, &lapb_list);
	lapb_hold(lapb);
	}

	static struct lapb_cb __lapb_devtostruct(struct net_device dev)
	{
	struct list_head *entry;
	struct lapb_cb lapb, use = NULL;

	list_for_each(entry, &lapb_list) {
	lapb = list_entry(entry, struct lapb_cb, node);
	if (lapb->dev == dev) {
	use = lapb;
	break;
	}
	}

	if (use)
	lapb_hold(use);

	return use;
	}

	static struct lapb_cb lapb_devtostruct(struct net_device dev)
	{
	struct lapb_cb *rc;

	read_lock_bh(&lapb_list_lock);
	rc = __lapb_devtostruct(dev);
	read_unlock_bh(&lapb_list_lock);

	return rc;
	}
	/*
	* Create an empty LAPB control block.
	*/
	static struct lapb_cb *lapb_create_cb(void)
	{
	struct lapb_cb lapb = kzalloc(sizeof(lapb), GFP_ATOMIC);

	if (!lapb)
	goto out;

	skb_queue_head_init(&lapb->write_queue);
	skb_queue_head_init(&lapb->ack_queue);

	timer_setup(&lapb->t1timer, NULL, 0);
	timer_setup(&lapb->t2timer, NULL, 0);

	lapb->t1 = LAPB_DEFAULT_T1;
	lapb->t2 = LAPB_DEFAULT_T2;
	lapb->n2 = LAPB_DEFAULT_N2;
	lapb->mode = LAPB_DEFAULT_MODE;
	lapb->window = LAPB_DEFAULT_WINDOW;
	lapb->state = LAPB_STATE_0;
	refcount_set(&lapb->refcnt, 1);
	out:
	return lapb;
	}

	int lapb_register(struct net_device *dev,
	const struct lapb_register_struct *callbacks)
	{
	struct lapb_cb *lapb;
	int rc = LAPB_BADTOKEN;

	write_lock_bh(&lapb_list_lock);

	lapb = __lapb_devtostruct(dev);
	if (lapb) {
	lapb_put(lapb);
	goto out;
	}

	lapb = lapb_create_cb();
	rc = LAPB_NOMEM;
	if (!lapb)
	goto out;

	lapb->dev = dev;
	lapb->callbacks = callbacks;

	__lapb_insert_cb(lapb);

	lapb_start_t1timer(lapb);

	rc = LAPB_OK;
	out:
	write_unlock_bh(&lapb_list_lock);
	return rc;
	}
	EXPORT_SYMBOL(lapb_register);

	int lapb_unregister(struct net_device *dev)
	{
	struct lapb_cb *lapb;
	int rc = LAPB_BADTOKEN;

	write_lock_bh(&lapb_list_lock);
	lapb = __lapb_devtostruct(dev);
	if (!lapb)
	goto out;
	lapb_put(lapb);

	lapb_stop_t1timer(lapb);
	lapb_stop_t2timer(lapb);

	lapb_clear_queues(lapb);

	__lapb_remove_cb(lapb);

	lapb_put(lapb);
	rc = LAPB_OK;
	out:
	write_unlock_bh(&lapb_list_lock);
	return rc;
	}
	EXPORT_SYMBOL(lapb_unregister);

	int lapb_getparms(struct net_device dev, struct lapb_parms_struct parms)
	{
	int rc = LAPB_BADTOKEN;
	struct lapb_cb *lapb = lapb_devtostruct(dev);

	if (!lapb)
	goto out;

	parms->t1 = lapb->t1 / HZ;
	parms->t2 = lapb->t2 / HZ;
	parms->n2 = lapb->n2;
	parms->n2count = lapb->n2count;
	parms->state = lapb->state;
	parms->window = lapb->window;
	parms->mode = lapb->mode;

	if (!timer_pending(&lapb->t1timer))
	parms->t1timer = 0;
	else
	parms->t1timer = (lapb->t1timer.expires - jiffies) / HZ;

	if (!timer_pending(&lapb->t2timer))
	parms->t2timer = 0;
	else
	parms->t2timer = (lapb->t2timer.expires - jiffies) / HZ;

	lapb_put(lapb);
	rc = LAPB_OK;
	out:
	return rc;
	}
	EXPORT_SYMBOL(lapb_getparms);

	int lapb_setparms(struct net_device dev, struct lapb_parms_struct parms)
	{
	int rc = LAPB_BADTOKEN;
	struct lapb_cb *lapb = lapb_devtostruct(dev);

	if (!lapb)
	goto out;

	rc = LAPB_INVALUE;
	if (parms->t1 < 1 \|\| parms->t2 < 1 \|\| parms->n2 < 1)
	goto out_put;

	if (lapb->state == LAPB_STATE_0) {
	if (parms->mode & LAPB_EXTENDED) {
	if (parms->window < 1 \|\| parms->window > 127)
	goto out_put;
	} else {
	if (parms->window < 1 \|\| parms->window > 7)
	goto out_put;
	}
	lapb->mode = parms->mode;
	lapb->window = parms->window;
	}

	lapb->t1 = parms->t1 * HZ;
	lapb->t2 = parms->t2 * HZ;
	lapb->n2 = parms->n2;

	rc = LAPB_OK;
	out_put:
	lapb_put(lapb);
	out:
	return rc;
	}
	EXPORT_SYMBOL(lapb_setparms);

	int lapb_connect_request(struct net_device *dev)
	{
	struct lapb_cb *lapb = lapb_devtostruct(dev);
	int rc = LAPB_BADTOKEN;

	if (!lapb)
	goto out;

	rc = LAPB_OK;
	if (lapb->state == LAPB_STATE_1)
	goto out_put;

	rc = LAPB_CONNECTED;
	if (lapb->state == LAPB_STATE_3 \|\| lapb->state == LAPB_STATE_4)
	goto out_put;

	lapb_establish_data_link(lapb);

	lapb_dbg(0, "(%p) S0 -> S1\n", lapb->dev);
	lapb->state = LAPB_STATE_1;

	rc = LAPB_OK;
	out_put:
	lapb_put(lapb);
	out:
	return rc;
	}
	EXPORT_SYMBOL(lapb_connect_request);

	int lapb_disconnect_request(struct net_device *dev)
	{
	struct lapb_cb *lapb = lapb_devtostruct(dev);
	int rc = LAPB_BADTOKEN;

	if (!lapb)
	goto out;

	switch (lapb->state) {
	case LAPB_STATE_0:
	rc = LAPB_NOTCONNECTED;
	goto out_put;

	case LAPB_STATE_1:
	lapb_dbg(1, "(%p) S1 TX DISC(1)\n", lapb->dev);
	lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev);
	lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
	lapb->state = LAPB_STATE_0;
	lapb_start_t1timer(lapb);
	rc = LAPB_NOTCONNECTED;
	goto out_put;

	case LAPB_STATE_2:
	rc = LAPB_OK;
	goto out_put;
	}

	lapb_clear_queues(lapb);
	lapb->n2count = 0;
	lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
	lapb_start_t1timer(lapb);
	lapb_stop_t2timer(lapb);
	lapb->state = LAPB_STATE_2;

	lapb_dbg(1, "(%p) S3 DISC(1)\n", lapb->dev);
	lapb_dbg(0, "(%p) S3 -> S2\n", lapb->dev);

	rc = LAPB_OK;
	out_put:
	lapb_put(lapb);
	out:
	return rc;
	}
	EXPORT_SYMBOL(lapb_disconnect_request);

	int lapb_data_request(struct net_device dev, struct sk_buff skb)
	{
	struct lapb_cb *lapb = lapb_devtostruct(dev);
	int rc = LAPB_BADTOKEN;

	if (!lapb)
	goto out;

	rc = LAPB_NOTCONNECTED;
	if (lapb->state != LAPB_STATE_3 && lapb->state != LAPB_STATE_4)
	goto out_put;

	skb_queue_tail(&lapb->write_queue, skb);
	lapb_kick(lapb);
	rc = LAPB_OK;
	out_put:
	lapb_put(lapb);
	out:
	return rc;
	}
	EXPORT_SYMBOL(lapb_data_request);

	int lapb_data_received(struct net_device dev, struct sk_buff skb)
	{
	struct lapb_cb *lapb = lapb_devtostruct(dev);
	int rc = LAPB_BADTOKEN;

	if (lapb) {
	lapb_data_input(lapb, skb);
	lapb_put(lapb);
	rc = LAPB_OK;
	}

	return rc;
	}
	EXPORT_SYMBOL(lapb_data_received);

	void lapb_connect_confirmation(struct lapb_cb *lapb, int reason)
	{
	if (lapb->callbacks->connect_confirmation)
	lapb->callbacks->connect_confirmation(lapb->dev, reason);
	}

	void lapb_connect_indication(struct lapb_cb *lapb, int reason)
	{
	if (lapb->callbacks->connect_indication)
	lapb->callbacks->connect_indication(lapb->dev, reason);
	}

	void lapb_disconnect_confirmation(struct lapb_cb *lapb, int reason)
	{
	if (lapb->callbacks->disconnect_confirmation)
	lapb->callbacks->disconnect_confirmation(lapb->dev, reason);
	}

	void lapb_disconnect_indication(struct lapb_cb *lapb, int reason)
	{
	if (lapb->callbacks->disconnect_indication)
	lapb->callbacks->disconnect_indication(lapb->dev, reason);
	}

	int lapb_data_indication(struct lapb_cb lapb, struct sk_buff skb)
	{
	if (lapb->callbacks->data_indication)
	return lapb->callbacks->data_indication(lapb->dev, skb);

	kfree_skb(skb);
	return NET_RX_SUCCESS; /* For now; must be != NET_RX_DROP */
	}

	int lapb_data_transmit(struct lapb_cb lapb, struct sk_buff skb)
	{
	int used = 0;

	if (lapb->callbacks->data_transmit) {
	lapb->callbacks->data_transmit(lapb->dev, skb);
	used = 1;
	}

	return used;
	}

	/* Handle device status changes. */
	static int lapb_device_event(struct notifier_block *this, unsigned long event,
	void *ptr)
	{
	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
	struct lapb_cb *lapb;

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

	if (dev->type != ARPHRD_X25)
	return NOTIFY_DONE;

	lapb = lapb_devtostruct(dev);
	if (!lapb)
	return NOTIFY_DONE;

	switch (event) {
	case NETDEV_UP:
	lapb_dbg(0, "(%p) Interface up: %s\n", dev, dev->name);

	if (netif_carrier_ok(dev)) {
	lapb_dbg(0, "(%p): Carrier is already up: %s\n", dev,
	dev->name);
	if (lapb->mode & LAPB_DCE) {
	lapb_start_t1timer(lapb);
	} else {
	if (lapb->state == LAPB_STATE_0) {
	lapb->state = LAPB_STATE_1;
	lapb_establish_data_link(lapb);
	}
	}
	}
	break;
	case NETDEV_GOING_DOWN:
	if (netif_carrier_ok(dev))
	lapb_disconnect_request(dev);
	break;
	case NETDEV_DOWN:
	lapb_dbg(0, "(%p) Interface down: %s\n", dev, dev->name);
	lapb_dbg(0, "(%p) S%d -> S0\n", dev, lapb->state);
	lapb_clear_queues(lapb);
	lapb->state = LAPB_STATE_0;
	lapb->n2count = 0;
	lapb_stop_t1timer(lapb);
	lapb_stop_t2timer(lapb);
	break;
	case NETDEV_CHANGE:
	if (netif_carrier_ok(dev)) {
	lapb_dbg(0, "(%p): Carrier detected: %s\n", dev,
	dev->name);
	if (lapb->mode & LAPB_DCE) {
	lapb_start_t1timer(lapb);
	} else {
	if (lapb->state == LAPB_STATE_0) {
	lapb->state = LAPB_STATE_1;
	lapb_establish_data_link(lapb);
	}
	}
	} else {
	lapb_dbg(0, "(%p) Carrier lost: %s\n", dev, dev->name);
	lapb_dbg(0, "(%p) S%d -> S0\n", dev, lapb->state);
	lapb_clear_queues(lapb);
	lapb->state = LAPB_STATE_0;
	lapb->n2count = 0;
	lapb_stop_t1timer(lapb);
	lapb_stop_t2timer(lapb);
	}
	break;
	}

	return NOTIFY_DONE;
	}

	static struct notifier_block lapb_dev_notifier = {
	.notifier_call = lapb_device_event,
	};

	static int __init lapb_init(void)
	{
	return register_netdevice_notifier(&lapb_dev_notifier);
	}

	static void __exit lapb_exit(void)
	{
	WARN_ON(!list_empty(&lapb_list));

	unregister_netdevice_notifier(&lapb_dev_notifier);
	}

	MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
	MODULE_DESCRIPTION("The X.25 Link Access Procedure B link layer protocol");
	MODULE_LICENSE("GPL");

	module_init(lapb_init);
	module_exit(lapb_exit);