Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

7 files changed, 1849 insertions, 0 deletions

diff --git a/net/lapb/Kconfig b/net/lapb/Kconfig
new file mode 100644
index 000000000..da87b47f0
--- /dev/null
+++ b/net/lapb/Kconfig
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# LAPB Data Link Drive
+#
+
+config LAPB
+	tristate "LAPB Data Link Driver"
+	help
+	  Link Access Procedure, Balanced (LAPB) is the data link layer (i.e.
+	  the lower) part of the X.25 protocol. It offers a reliable
+	  connection service to exchange data frames with one other host, and
+	  it is used to transport higher level protocols (mostly X.25 Packet
+	  Layer, the higher part of X.25, but others are possible as well).
+	  Usually, LAPB is used with specialized X.21 network cards, but Linux
+	  currently supports LAPB only over Ethernet connections. If you want
+	  to use LAPB connections over Ethernet, say Y here and to "LAPB over
+	  Ethernet driver" below. Read
+	  <file:Documentation/networking/lapb-module.rst> for technical
+	  details.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called lapb.  If unsure, say N.
diff --git a/net/lapb/Makefile b/net/lapb/Makefile
new file mode 100644
index 000000000..7be91b4c0
--- /dev/null
+++ b/net/lapb/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for the Linux LAPB layer.
+#
+
+obj-$(CONFIG_LAPB) += lapb.o
+
+lapb-y := lapb_in.o lapb_out.o lapb_subr.o lapb_timer.o lapb_iface.o
diff --git a/net/lapb/lapb_iface.c b/net/lapb/lapb_iface.c
new file mode 100644
index 000000000..0971ca48b
--- /dev/null
+++ b/net/lapb/lapb_iface.c
@@ -0,0 +1,553 @@
+// 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 lapb_cb *lapb, *use = NULL;
+
+	list_for_each_entry(lapb, &lapb_list, 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->t1timer_running = false;
+	lapb->t2timer_running = false;
+
+	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;
+
+	spin_lock_init(&lapb->lock);
+	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);
+
+	/* Wait for other refs to "lapb" to drop */
+	while (refcount_read(&lapb->refcnt) > 2)
+		usleep_range(1, 10);
+
+	spin_lock_bh(&lapb->lock);
+
+	lapb_stop_t1timer(lapb);
+	lapb_stop_t2timer(lapb);
+
+	lapb_clear_queues(lapb);
+
+	spin_unlock_bh(&lapb->lock);
+
+	/* Wait for running timers to stop */
+	del_timer_sync(&lapb->t1timer);
+	del_timer_sync(&lapb->t2timer);
+
+	__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;
+
+	spin_lock_bh(&lapb->lock);
+
+	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;
+
+	spin_unlock_bh(&lapb->lock);
+	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;
+
+	spin_lock_bh(&lapb->lock);
+
+	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:
+	spin_unlock_bh(&lapb->lock);
+	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;
+
+	spin_lock_bh(&lapb->lock);
+
+	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:
+	spin_unlock_bh(&lapb->lock);
+	lapb_put(lapb);
+out:
+	return rc;
+}
+EXPORT_SYMBOL(lapb_connect_request);
+
+static int __lapb_disconnect_request(struct lapb_cb *lapb)
+{
+	switch (lapb->state) {
+	case LAPB_STATE_0:
+		return LAPB_NOTCONNECTED;
+
+	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);
+		return LAPB_NOTCONNECTED;
+
+	case LAPB_STATE_2:
+		return LAPB_OK;
+	}
+
+	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);
+
+	return LAPB_OK;
+}
+
+int lapb_disconnect_request(struct net_device *dev)
+{
+	struct lapb_cb *lapb = lapb_devtostruct(dev);
+	int rc = LAPB_BADTOKEN;
+
+	if (!lapb)
+		goto out;
+
+	spin_lock_bh(&lapb->lock);
+
+	rc = __lapb_disconnect_request(lapb);
+
+	spin_unlock_bh(&lapb->lock);
+	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;
+
+	spin_lock_bh(&lapb->lock);
+
+	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:
+	spin_unlock_bh(&lapb->lock);
+	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) {
+		spin_lock_bh(&lapb->lock);
+		lapb_data_input(lapb, skb);
+		spin_unlock_bh(&lapb->lock);
+		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;
+
+	spin_lock_bh(&lapb->lock);
+
+	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(lapb);
+		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;
+	}
+
+	spin_unlock_bh(&lapb->lock);
+	lapb_put(lapb);
+	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);
diff --git a/net/lapb/lapb_in.c b/net/lapb/lapb_in.c
new file mode 100644
index 000000000..38ae23c09
--- /dev/null
+++ b/net/lapb/lapb_in.c
@@ -0,0 +1,556 @@
+// 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 Naulor	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/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/inet.h>
+#include <linux/netdevice.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 <net/lapb.h>
+
+/*
+ *	State machine for state 0, Disconnected State.
+ *	The handling of the timer(s) is in file lapb_timer.c.
+ */
+static void lapb_state0_machine(struct lapb_cb *lapb, struct sk_buff *skb,
+				struct lapb_frame *frame)
+{
+	switch (frame->type) {
+	case LAPB_SABM:
+		lapb_dbg(1, "(%p) S0 RX SABM(%d)\n", lapb->dev, frame->pf);
+		if (lapb->mode & LAPB_EXTENDED) {
+			lapb_dbg(1, "(%p) S0 TX DM(%d)\n",
+				 lapb->dev, frame->pf);
+			lapb_send_control(lapb, LAPB_DM, frame->pf,
+					  LAPB_RESPONSE);
+		} else {
+			lapb_dbg(1, "(%p) S0 TX UA(%d)\n",
+				 lapb->dev, frame->pf);
+			lapb_dbg(0, "(%p) S0 -> S3\n", lapb->dev);
+			lapb_send_control(lapb, LAPB_UA, frame->pf,
+					  LAPB_RESPONSE);
+			lapb_stop_t1timer(lapb);
+			lapb_stop_t2timer(lapb);
+			lapb->state     = LAPB_STATE_3;
+			lapb->condition = 0x00;
+			lapb->n2count   = 0;
+			lapb->vs        = 0;
+			lapb->vr        = 0;
+			lapb->va        = 0;
+			lapb_connect_indication(lapb, LAPB_OK);
+		}
+		break;
+
+	case LAPB_SABME:
+		lapb_dbg(1, "(%p) S0 RX SABME(%d)\n", lapb->dev, frame->pf);
+		if (lapb->mode & LAPB_EXTENDED) {
+			lapb_dbg(1, "(%p) S0 TX UA(%d)\n",
+				 lapb->dev, frame->pf);
+			lapb_dbg(0, "(%p) S0 -> S3\n", lapb->dev);
+			lapb_send_control(lapb, LAPB_UA, frame->pf,
+					  LAPB_RESPONSE);
+			lapb_stop_t1timer(lapb);
+			lapb_stop_t2timer(lapb);
+			lapb->state     = LAPB_STATE_3;
+			lapb->condition = 0x00;
+			lapb->n2count   = 0;
+			lapb->vs        = 0;
+			lapb->vr        = 0;
+			lapb->va        = 0;
+			lapb_connect_indication(lapb, LAPB_OK);
+		} else {
+			lapb_dbg(1, "(%p) S0 TX DM(%d)\n",
+				 lapb->dev, frame->pf);
+			lapb_send_control(lapb, LAPB_DM, frame->pf,
+					  LAPB_RESPONSE);
+		}
+		break;
+
+	case LAPB_DISC:
+		lapb_dbg(1, "(%p) S0 RX DISC(%d)\n", lapb->dev, frame->pf);
+		lapb_dbg(1, "(%p) S0 TX UA(%d)\n", lapb->dev, frame->pf);
+		lapb_send_control(lapb, LAPB_UA, frame->pf, LAPB_RESPONSE);
+		break;
+
+	default:
+		break;
+	}
+
+	kfree_skb(skb);
+}
+
+/*
+ *	State machine for state 1, Awaiting Connection State.
+ *	The handling of the timer(s) is in file lapb_timer.c.
+ */
+static void lapb_state1_machine(struct lapb_cb *lapb, struct sk_buff *skb,
+				struct lapb_frame *frame)
+{
+	switch (frame->type) {
+	case LAPB_SABM:
+		lapb_dbg(1, "(%p) S1 RX SABM(%d)\n", lapb->dev, frame->pf);
+		if (lapb->mode & LAPB_EXTENDED) {
+			lapb_dbg(1, "(%p) S1 TX DM(%d)\n",
+				 lapb->dev, frame->pf);
+			lapb_send_control(lapb, LAPB_DM, frame->pf,
+					  LAPB_RESPONSE);
+		} else {
+			lapb_dbg(1, "(%p) S1 TX UA(%d)\n",
+				 lapb->dev, frame->pf);
+			lapb_send_control(lapb, LAPB_UA, frame->pf,
+					  LAPB_RESPONSE);
+		}
+		break;
+
+	case LAPB_SABME:
+		lapb_dbg(1, "(%p) S1 RX SABME(%d)\n", lapb->dev, frame->pf);
+		if (lapb->mode & LAPB_EXTENDED) {
+			lapb_dbg(1, "(%p) S1 TX UA(%d)\n",
+				 lapb->dev, frame->pf);
+			lapb_send_control(lapb, LAPB_UA, frame->pf,
+					  LAPB_RESPONSE);
+		} else {
+			lapb_dbg(1, "(%p) S1 TX DM(%d)\n",
+				 lapb->dev, frame->pf);
+			lapb_send_control(lapb, LAPB_DM, frame->pf,
+					  LAPB_RESPONSE);
+		}
+		break;
+
+	case LAPB_DISC:
+		lapb_dbg(1, "(%p) S1 RX DISC(%d)\n", lapb->dev, frame->pf);
+		lapb_dbg(1, "(%p) S1 TX DM(%d)\n", lapb->dev, frame->pf);
+		lapb_send_control(lapb, LAPB_DM, frame->pf, LAPB_RESPONSE);
+		break;
+
+	case LAPB_UA:
+		lapb_dbg(1, "(%p) S1 RX UA(%d)\n", lapb->dev, frame->pf);
+		if (frame->pf) {
+			lapb_dbg(0, "(%p) S1 -> S3\n", lapb->dev);
+			lapb_stop_t1timer(lapb);
+			lapb_stop_t2timer(lapb);
+			lapb->state     = LAPB_STATE_3;
+			lapb->condition = 0x00;
+			lapb->n2count   = 0;
+			lapb->vs        = 0;
+			lapb->vr        = 0;
+			lapb->va        = 0;
+			lapb_connect_confirmation(lapb, LAPB_OK);
+		}
+		break;
+
+	case LAPB_DM:
+		lapb_dbg(1, "(%p) S1 RX DM(%d)\n", lapb->dev, frame->pf);
+		if (frame->pf) {
+			lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev);
+			lapb_clear_queues(lapb);
+			lapb->state = LAPB_STATE_0;
+			lapb_start_t1timer(lapb);
+			lapb_stop_t2timer(lapb);
+			lapb_disconnect_indication(lapb, LAPB_REFUSED);
+		}
+		break;
+	}
+
+	kfree_skb(skb);
+}
+
+/*
+ *	State machine for state 2, Awaiting Release State.
+ *	The handling of the timer(s) is in file lapb_timer.c
+ */
+static void lapb_state2_machine(struct lapb_cb *lapb, struct sk_buff *skb,
+				struct lapb_frame *frame)
+{
+	switch (frame->type) {
+	case LAPB_SABM:
+	case LAPB_SABME:
+		lapb_dbg(1, "(%p) S2 RX {SABM,SABME}(%d)\n",
+			 lapb->dev, frame->pf);
+		lapb_dbg(1, "(%p) S2 TX DM(%d)\n", lapb->dev, frame->pf);
+		lapb_send_control(lapb, LAPB_DM, frame->pf, LAPB_RESPONSE);
+		break;
+
+	case LAPB_DISC:
+		lapb_dbg(1, "(%p) S2 RX DISC(%d)\n", lapb->dev, frame->pf);
+		lapb_dbg(1, "(%p) S2 TX UA(%d)\n", lapb->dev, frame->pf);
+		lapb_send_control(lapb, LAPB_UA, frame->pf, LAPB_RESPONSE);
+		break;
+
+	case LAPB_UA:
+		lapb_dbg(1, "(%p) S2 RX UA(%d)\n", lapb->dev, frame->pf);
+		if (frame->pf) {
+			lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev);
+			lapb->state = LAPB_STATE_0;
+			lapb_start_t1timer(lapb);
+			lapb_stop_t2timer(lapb);
+			lapb_disconnect_confirmation(lapb, LAPB_OK);
+		}
+		break;
+
+	case LAPB_DM:
+		lapb_dbg(1, "(%p) S2 RX DM(%d)\n", lapb->dev, frame->pf);
+		if (frame->pf) {
+			lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev);
+			lapb->state = LAPB_STATE_0;
+			lapb_start_t1timer(lapb);
+			lapb_stop_t2timer(lapb);
+			lapb_disconnect_confirmation(lapb, LAPB_NOTCONNECTED);
+		}
+		break;
+
+	case LAPB_I:
+	case LAPB_REJ:
+	case LAPB_RNR:
+	case LAPB_RR:
+		lapb_dbg(1, "(%p) S2 RX {I,REJ,RNR,RR}(%d)\n",
+		       lapb->dev, frame->pf);
+		lapb_dbg(1, "(%p) S2 RX DM(%d)\n", lapb->dev, frame->pf);
+		if (frame->pf)
+			lapb_send_control(lapb, LAPB_DM, frame->pf,
+					  LAPB_RESPONSE);
+		break;
+	}
+
+	kfree_skb(skb);
+}
+
+/*
+ *	State machine for state 3, Connected State.
+ *	The handling of the timer(s) is in file lapb_timer.c
+ */
+static void lapb_state3_machine(struct lapb_cb *lapb, struct sk_buff *skb,
+				struct lapb_frame *frame)
+{
+	int queued = 0;
+	int modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS :
+						     LAPB_SMODULUS;
+
+	switch (frame->type) {
+	case LAPB_SABM:
+		lapb_dbg(1, "(%p) S3 RX SABM(%d)\n", lapb->dev, frame->pf);
+		if (lapb->mode & LAPB_EXTENDED) {
+			lapb_dbg(1, "(%p) S3 TX DM(%d)\n",
+				 lapb->dev, frame->pf);
+			lapb_send_control(lapb, LAPB_DM, frame->pf,
+					  LAPB_RESPONSE);
+		} else {
+			lapb_dbg(1, "(%p) S3 TX UA(%d)\n",
+				 lapb->dev, frame->pf);
+			lapb_send_control(lapb, LAPB_UA, frame->pf,
+					  LAPB_RESPONSE);
+			lapb_stop_t1timer(lapb);
+			lapb_stop_t2timer(lapb);
+			lapb->condition = 0x00;
+			lapb->n2count   = 0;
+			lapb->vs        = 0;
+			lapb->vr        = 0;
+			lapb->va        = 0;
+			lapb_requeue_frames(lapb);
+		}
+		break;
+
+	case LAPB_SABME:
+		lapb_dbg(1, "(%p) S3 RX SABME(%d)\n", lapb->dev, frame->pf);
+		if (lapb->mode & LAPB_EXTENDED) {
+			lapb_dbg(1, "(%p) S3 TX UA(%d)\n",
+				 lapb->dev, frame->pf);
+			lapb_send_control(lapb, LAPB_UA, frame->pf,
+					  LAPB_RESPONSE);
+			lapb_stop_t1timer(lapb);
+			lapb_stop_t2timer(lapb);
+			lapb->condition = 0x00;
+			lapb->n2count   = 0;
+			lapb->vs        = 0;
+			lapb->vr        = 0;
+			lapb->va        = 0;
+			lapb_requeue_frames(lapb);
+		} else {
+			lapb_dbg(1, "(%p) S3 TX DM(%d)\n",
+				 lapb->dev, frame->pf);
+			lapb_send_control(lapb, LAPB_DM, frame->pf,
+					  LAPB_RESPONSE);
+		}
+		break;
+
+	case LAPB_DISC:
+		lapb_dbg(1, "(%p) S3 RX DISC(%d)\n", lapb->dev, frame->pf);
+		lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev);
+		lapb_clear_queues(lapb);
+		lapb_send_control(lapb, LAPB_UA, frame->pf, LAPB_RESPONSE);
+		lapb_start_t1timer(lapb);
+		lapb_stop_t2timer(lapb);
+		lapb->state = LAPB_STATE_0;
+		lapb_disconnect_indication(lapb, LAPB_OK);
+		break;
+
+	case LAPB_DM:
+		lapb_dbg(1, "(%p) S3 RX DM(%d)\n", lapb->dev, frame->pf);
+		lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev);
+		lapb_clear_queues(lapb);
+		lapb->state = LAPB_STATE_0;
+		lapb_start_t1timer(lapb);
+		lapb_stop_t2timer(lapb);
+		lapb_disconnect_indication(lapb, LAPB_NOTCONNECTED);
+		break;
+
+	case LAPB_RNR:
+		lapb_dbg(1, "(%p) S3 RX RNR(%d) R%d\n",
+			 lapb->dev, frame->pf, frame->nr);
+		lapb->condition |= LAPB_PEER_RX_BUSY_CONDITION;
+		lapb_check_need_response(lapb, frame->cr, frame->pf);
+		if (lapb_validate_nr(lapb, frame->nr)) {
+			lapb_check_iframes_acked(lapb, frame->nr);
+		} else {
+			lapb->frmr_data = *frame;
+			lapb->frmr_type = LAPB_FRMR_Z;
+			lapb_transmit_frmr(lapb);
+			lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
+			lapb_start_t1timer(lapb);
+			lapb_stop_t2timer(lapb);
+			lapb->state   = LAPB_STATE_4;
+			lapb->n2count = 0;
+		}
+		break;
+
+	case LAPB_RR:
+		lapb_dbg(1, "(%p) S3 RX RR(%d) R%d\n",
+			 lapb->dev, frame->pf, frame->nr);
+		lapb->condition &= ~LAPB_PEER_RX_BUSY_CONDITION;
+		lapb_check_need_response(lapb, frame->cr, frame->pf);
+		if (lapb_validate_nr(lapb, frame->nr)) {
+			lapb_check_iframes_acked(lapb, frame->nr);
+		} else {
+			lapb->frmr_data = *frame;
+			lapb->frmr_type = LAPB_FRMR_Z;
+			lapb_transmit_frmr(lapb);
+			lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
+			lapb_start_t1timer(lapb);
+			lapb_stop_t2timer(lapb);
+			lapb->state   = LAPB_STATE_4;
+			lapb->n2count = 0;
+		}
+		break;
+
+	case LAPB_REJ:
+		lapb_dbg(1, "(%p) S3 RX REJ(%d) R%d\n",
+			 lapb->dev, frame->pf, frame->nr);
+		lapb->condition &= ~LAPB_PEER_RX_BUSY_CONDITION;
+		lapb_check_need_response(lapb, frame->cr, frame->pf);
+		if (lapb_validate_nr(lapb, frame->nr)) {
+			lapb_frames_acked(lapb, frame->nr);
+			lapb_stop_t1timer(lapb);
+			lapb->n2count = 0;
+			lapb_requeue_frames(lapb);
+		} else {
+			lapb->frmr_data = *frame;
+			lapb->frmr_type = LAPB_FRMR_Z;
+			lapb_transmit_frmr(lapb);
+			lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
+			lapb_start_t1timer(lapb);
+			lapb_stop_t2timer(lapb);
+			lapb->state   = LAPB_STATE_4;
+			lapb->n2count = 0;
+		}
+		break;
+
+	case LAPB_I:
+		lapb_dbg(1, "(%p) S3 RX I(%d) S%d R%d\n",
+			 lapb->dev, frame->pf, frame->ns, frame->nr);
+		if (!lapb_validate_nr(lapb, frame->nr)) {
+			lapb->frmr_data = *frame;
+			lapb->frmr_type = LAPB_FRMR_Z;
+			lapb_transmit_frmr(lapb);
+			lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
+			lapb_start_t1timer(lapb);
+			lapb_stop_t2timer(lapb);
+			lapb->state   = LAPB_STATE_4;
+			lapb->n2count = 0;
+			break;
+		}
+		if (lapb->condition & LAPB_PEER_RX_BUSY_CONDITION)
+			lapb_frames_acked(lapb, frame->nr);
+		else
+			lapb_check_iframes_acked(lapb, frame->nr);
+
+		if (frame->ns == lapb->vr) {
+			int cn;
+			cn = lapb_data_indication(lapb, skb);
+			queued = 1;
+			/*
+			 * If upper layer has dropped the frame, we
+			 * basically ignore any further protocol
+			 * processing. This will cause the peer
+			 * to re-transmit the frame later like
+			 * a frame lost on the wire.
+			 */
+			if (cn == NET_RX_DROP) {
+				pr_debug("rx congestion\n");
+				break;
+			}
+			lapb->vr = (lapb->vr + 1) % modulus;
+			lapb->condition &= ~LAPB_REJECT_CONDITION;
+			if (frame->pf)
+				lapb_enquiry_response(lapb);
+			else {
+				if (!(lapb->condition &
+				      LAPB_ACK_PENDING_CONDITION)) {
+					lapb->condition |= LAPB_ACK_PENDING_CONDITION;
+					lapb_start_t2timer(lapb);
+				}
+			}
+		} else {
+			if (lapb->condition & LAPB_REJECT_CONDITION) {
+				if (frame->pf)
+					lapb_enquiry_response(lapb);
+			} else {
+				lapb_dbg(1, "(%p) S3 TX REJ(%d) R%d\n",
+					 lapb->dev, frame->pf, lapb->vr);
+				lapb->condition |= LAPB_REJECT_CONDITION;
+				lapb_send_control(lapb, LAPB_REJ, frame->pf,
+						  LAPB_RESPONSE);
+				lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
+			}
+		}
+		break;
+
+	case LAPB_FRMR:
+		lapb_dbg(1, "(%p) S3 RX FRMR(%d) %5ph\n",
+			 lapb->dev, frame->pf,
+			 skb->data);
+		lapb_establish_data_link(lapb);
+		lapb_dbg(0, "(%p) S3 -> S1\n", lapb->dev);
+		lapb_requeue_frames(lapb);
+		lapb->state = LAPB_STATE_1;
+		break;
+
+	case LAPB_ILLEGAL:
+		lapb_dbg(1, "(%p) S3 RX ILLEGAL(%d)\n", lapb->dev, frame->pf);
+		lapb->frmr_data = *frame;
+		lapb->frmr_type = LAPB_FRMR_W;
+		lapb_transmit_frmr(lapb);
+		lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
+		lapb_start_t1timer(lapb);
+		lapb_stop_t2timer(lapb);
+		lapb->state   = LAPB_STATE_4;
+		lapb->n2count = 0;
+		break;
+	}
+
+	if (!queued)
+		kfree_skb(skb);
+}
+
+/*
+ *	State machine for state 4, Frame Reject State.
+ *	The handling of the timer(s) is in file lapb_timer.c.
+ */
+static void lapb_state4_machine(struct lapb_cb *lapb, struct sk_buff *skb,
+				struct lapb_frame *frame)
+{
+	switch (frame->type) {
+	case LAPB_SABM:
+		lapb_dbg(1, "(%p) S4 RX SABM(%d)\n", lapb->dev, frame->pf);
+		if (lapb->mode & LAPB_EXTENDED) {
+			lapb_dbg(1, "(%p) S4 TX DM(%d)\n",
+				 lapb->dev, frame->pf);
+			lapb_send_control(lapb, LAPB_DM, frame->pf,
+					  LAPB_RESPONSE);
+		} else {
+			lapb_dbg(1, "(%p) S4 TX UA(%d)\n",
+				 lapb->dev, frame->pf);
+			lapb_dbg(0, "(%p) S4 -> S3\n", lapb->dev);
+			lapb_send_control(lapb, LAPB_UA, frame->pf,
+					  LAPB_RESPONSE);
+			lapb_stop_t1timer(lapb);
+			lapb_stop_t2timer(lapb);
+			lapb->state     = LAPB_STATE_3;
+			lapb->condition = 0x00;
+			lapb->n2count   = 0;
+			lapb->vs        = 0;
+			lapb->vr        = 0;
+			lapb->va        = 0;
+			lapb_connect_indication(lapb, LAPB_OK);
+		}
+		break;
+
+	case LAPB_SABME:
+		lapb_dbg(1, "(%p) S4 RX SABME(%d)\n", lapb->dev, frame->pf);
+		if (lapb->mode & LAPB_EXTENDED) {
+			lapb_dbg(1, "(%p) S4 TX UA(%d)\n",
+				 lapb->dev, frame->pf);
+			lapb_dbg(0, "(%p) S4 -> S3\n", lapb->dev);
+			lapb_send_control(lapb, LAPB_UA, frame->pf,
+					  LAPB_RESPONSE);
+			lapb_stop_t1timer(lapb);
+			lapb_stop_t2timer(lapb);
+			lapb->state     = LAPB_STATE_3;
+			lapb->condition = 0x00;
+			lapb->n2count   = 0;
+			lapb->vs        = 0;
+			lapb->vr        = 0;
+			lapb->va        = 0;
+			lapb_connect_indication(lapb, LAPB_OK);
+		} else {
+			lapb_dbg(1, "(%p) S4 TX DM(%d)\n",
+				 lapb->dev, frame->pf);
+			lapb_send_control(lapb, LAPB_DM, frame->pf,
+					  LAPB_RESPONSE);
+		}
+		break;
+	}
+
+	kfree_skb(skb);
+}
+
+/*
+ *	Process an incoming LAPB frame
+ */
+void lapb_data_input(struct lapb_cb *lapb, struct sk_buff *skb)
+{
+	struct lapb_frame frame;
+
+	if (lapb_decode(lapb, skb, &frame) < 0) {
+		kfree_skb(skb);
+		return;
+	}
+
+	switch (lapb->state) {
+	case LAPB_STATE_0:
+		lapb_state0_machine(lapb, skb, &frame); break;
+	case LAPB_STATE_1:
+		lapb_state1_machine(lapb, skb, &frame); break;
+	case LAPB_STATE_2:
+		lapb_state2_machine(lapb, skb, &frame); break;
+	case LAPB_STATE_3:
+		lapb_state3_machine(lapb, skb, &frame); break;
+	case LAPB_STATE_4:
+		lapb_state4_machine(lapb, skb, &frame); break;
+	}
+
+	lapb_kick(lapb);
+}
diff --git a/net/lapb/lapb_out.c b/net/lapb/lapb_out.c
new file mode 100644
index 000000000..a966d29c7
--- /dev/null
+++ b/net/lapb/lapb_out.c
@@ -0,0 +1,205 @@
+// 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.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/inet.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 <net/lapb.h>
+
+/*
+ *  This procedure is passed a buffer descriptor for an iframe. It builds
+ *  the rest of the control part of the frame and then writes it out.
+ */
+static void lapb_send_iframe(struct lapb_cb *lapb, struct sk_buff *skb, int poll_bit)
+{
+	unsigned char *frame;
+
+	if (!skb)
+		return;
+
+	if (lapb->mode & LAPB_EXTENDED) {
+		frame = skb_push(skb, 2);
+
+		frame[0] = LAPB_I;
+		frame[0] |= lapb->vs << 1;
+		frame[1] = poll_bit ? LAPB_EPF : 0;
+		frame[1] |= lapb->vr << 1;
+	} else {
+		frame = skb_push(skb, 1);
+
+		*frame = LAPB_I;
+		*frame |= poll_bit ? LAPB_SPF : 0;
+		*frame |= lapb->vr << 5;
+		*frame |= lapb->vs << 1;
+	}
+
+	lapb_dbg(1, "(%p) S%d TX I(%d) S%d R%d\n",
+		 lapb->dev, lapb->state, poll_bit, lapb->vs, lapb->vr);
+
+	lapb_transmit_buffer(lapb, skb, LAPB_COMMAND);
+}
+
+void lapb_kick(struct lapb_cb *lapb)
+{
+	struct sk_buff *skb, *skbn;
+	unsigned short modulus, start, end;
+
+	modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
+	start = !skb_peek(&lapb->ack_queue) ? lapb->va : lapb->vs;
+	end   = (lapb->va + lapb->window) % modulus;
+
+	if (!(lapb->condition & LAPB_PEER_RX_BUSY_CONDITION) &&
+	    start != end && skb_peek(&lapb->write_queue)) {
+		lapb->vs = start;
+
+		/*
+		 * Dequeue the frame and copy it.
+		 */
+		skb = skb_dequeue(&lapb->write_queue);
+
+		do {
+			skbn = skb_copy(skb, GFP_ATOMIC);
+			if (!skbn) {
+				skb_queue_head(&lapb->write_queue, skb);
+				break;
+			}
+
+			if (skb->sk)
+				skb_set_owner_w(skbn, skb->sk);
+
+			/*
+			 * Transmit the frame copy.
+			 */
+			lapb_send_iframe(lapb, skbn, LAPB_POLLOFF);
+
+			lapb->vs = (lapb->vs + 1) % modulus;
+
+			/*
+			 * Requeue the original data frame.
+			 */
+			skb_queue_tail(&lapb->ack_queue, skb);
+
+		} while (lapb->vs != end && (skb = skb_dequeue(&lapb->write_queue)) != NULL);
+
+		lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
+
+		if (!lapb_t1timer_running(lapb))
+			lapb_start_t1timer(lapb);
+	}
+}
+
+void lapb_transmit_buffer(struct lapb_cb *lapb, struct sk_buff *skb, int type)
+{
+	unsigned char *ptr;
+
+	ptr = skb_push(skb, 1);
+
+	if (lapb->mode & LAPB_MLP) {
+		if (lapb->mode & LAPB_DCE) {
+			if (type == LAPB_COMMAND)
+				*ptr = LAPB_ADDR_C;
+			if (type == LAPB_RESPONSE)
+				*ptr = LAPB_ADDR_D;
+		} else {
+			if (type == LAPB_COMMAND)
+				*ptr = LAPB_ADDR_D;
+			if (type == LAPB_RESPONSE)
+				*ptr = LAPB_ADDR_C;
+		}
+	} else {
+		if (lapb->mode & LAPB_DCE) {
+			if (type == LAPB_COMMAND)
+				*ptr = LAPB_ADDR_A;
+			if (type == LAPB_RESPONSE)
+				*ptr = LAPB_ADDR_B;
+		} else {
+			if (type == LAPB_COMMAND)
+				*ptr = LAPB_ADDR_B;
+			if (type == LAPB_RESPONSE)
+				*ptr = LAPB_ADDR_A;
+		}
+	}
+
+	lapb_dbg(2, "(%p) S%d TX %3ph\n", lapb->dev, lapb->state, skb->data);
+
+	if (!lapb_data_transmit(lapb, skb))
+		kfree_skb(skb);
+}
+
+void lapb_establish_data_link(struct lapb_cb *lapb)
+{
+	lapb->condition = 0x00;
+	lapb->n2count   = 0;
+
+	if (lapb->mode & LAPB_EXTENDED) {
+		lapb_dbg(1, "(%p) S%d TX SABME(1)\n", lapb->dev, lapb->state);
+		lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
+	} else {
+		lapb_dbg(1, "(%p) S%d TX SABM(1)\n", lapb->dev, lapb->state);
+		lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
+	}
+
+	lapb_start_t1timer(lapb);
+	lapb_stop_t2timer(lapb);
+}
+
+void lapb_enquiry_response(struct lapb_cb *lapb)
+{
+	lapb_dbg(1, "(%p) S%d TX RR(1) R%d\n",
+		 lapb->dev, lapb->state, lapb->vr);
+
+	lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE);
+
+	lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
+}
+
+void lapb_timeout_response(struct lapb_cb *lapb)
+{
+	lapb_dbg(1, "(%p) S%d TX RR(0) R%d\n",
+		 lapb->dev, lapb->state, lapb->vr);
+	lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE);
+
+	lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
+}
+
+void lapb_check_iframes_acked(struct lapb_cb *lapb, unsigned short nr)
+{
+	if (lapb->vs == nr) {
+		lapb_frames_acked(lapb, nr);
+		lapb_stop_t1timer(lapb);
+		lapb->n2count = 0;
+	} else if (lapb->va != nr) {
+		lapb_frames_acked(lapb, nr);
+		lapb_start_t1timer(lapb);
+	}
+}
+
+void lapb_check_need_response(struct lapb_cb *lapb, int type, int pf)
+{
+	if (type == LAPB_COMMAND && pf)
+		lapb_enquiry_response(lapb);
+}
diff --git a/net/lapb/lapb_subr.c b/net/lapb/lapb_subr.c
new file mode 100644
index 000000000..592a22d86
--- /dev/null
+++ b/net/lapb/lapb_subr.c
@@ -0,0 +1,299 @@
+// 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
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/inet.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 <net/lapb.h>
+
+/*
+ *	This routine purges all the queues of frames.
+ */
+void lapb_clear_queues(struct lapb_cb *lapb)
+{
+	skb_queue_purge(&lapb->write_queue);
+	skb_queue_purge(&lapb->ack_queue);
+}
+
+/*
+ * This routine purges the input queue of those frames that have been
+ * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
+ * SDL diagram.
+ */
+void lapb_frames_acked(struct lapb_cb *lapb, unsigned short nr)
+{
+	struct sk_buff *skb;
+	int modulus;
+
+	modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
+
+	/*
+	 * Remove all the ack-ed frames from the ack queue.
+	 */
+	if (lapb->va != nr)
+		while (skb_peek(&lapb->ack_queue) && lapb->va != nr) {
+			skb = skb_dequeue(&lapb->ack_queue);
+			kfree_skb(skb);
+			lapb->va = (lapb->va + 1) % modulus;
+		}
+}
+
+void lapb_requeue_frames(struct lapb_cb *lapb)
+{
+	struct sk_buff *skb, *skb_prev = NULL;
+
+	/*
+	 * Requeue all the un-ack-ed frames on the output queue to be picked
+	 * up by lapb_kick called from the timer. This arrangement handles the
+	 * possibility of an empty output queue.
+	 */
+	while ((skb = skb_dequeue(&lapb->ack_queue)) != NULL) {
+		if (!skb_prev)
+			skb_queue_head(&lapb->write_queue, skb);
+		else
+			skb_append(skb_prev, skb, &lapb->write_queue);
+		skb_prev = skb;
+	}
+}
+
+/*
+ *	Validate that the value of nr is between va and vs. Return true or
+ *	false for testing.
+ */
+int lapb_validate_nr(struct lapb_cb *lapb, unsigned short nr)
+{
+	unsigned short vc = lapb->va;
+	int modulus;
+
+	modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
+
+	while (vc != lapb->vs) {
+		if (nr == vc)
+			return 1;
+		vc = (vc + 1) % modulus;
+	}
+
+	return nr == lapb->vs;
+}
+
+/*
+ *	This routine is the centralised routine for parsing the control
+ *	information for the different frame formats.
+ */
+int lapb_decode(struct lapb_cb *lapb, struct sk_buff *skb,
+		struct lapb_frame *frame)
+{
+	frame->type = LAPB_ILLEGAL;
+
+	lapb_dbg(2, "(%p) S%d RX %3ph\n", lapb->dev, lapb->state, skb->data);
+
+	/* We always need to look at 2 bytes, sometimes we need
+	 * to look at 3 and those cases are handled below.
+	 */
+	if (!pskb_may_pull(skb, 2))
+		return -1;
+
+	if (lapb->mode & LAPB_MLP) {
+		if (lapb->mode & LAPB_DCE) {
+			if (skb->data[0] == LAPB_ADDR_D)
+				frame->cr = LAPB_COMMAND;
+			if (skb->data[0] == LAPB_ADDR_C)
+				frame->cr = LAPB_RESPONSE;
+		} else {
+			if (skb->data[0] == LAPB_ADDR_C)
+				frame->cr = LAPB_COMMAND;
+			if (skb->data[0] == LAPB_ADDR_D)
+				frame->cr = LAPB_RESPONSE;
+		}
+	} else {
+		if (lapb->mode & LAPB_DCE) {
+			if (skb->data[0] == LAPB_ADDR_B)
+				frame->cr = LAPB_COMMAND;
+			if (skb->data[0] == LAPB_ADDR_A)
+				frame->cr = LAPB_RESPONSE;
+		} else {
+			if (skb->data[0] == LAPB_ADDR_A)
+				frame->cr = LAPB_COMMAND;
+			if (skb->data[0] == LAPB_ADDR_B)
+				frame->cr = LAPB_RESPONSE;
+		}
+	}
+
+	skb_pull(skb, 1);
+
+	if (lapb->mode & LAPB_EXTENDED) {
+		if (!(skb->data[0] & LAPB_S)) {
+			if (!pskb_may_pull(skb, 2))
+				return -1;
+			/*
+			 * I frame - carries NR/NS/PF
+			 */
+			frame->type       = LAPB_I;
+			frame->ns         = (skb->data[0] >> 1) & 0x7F;
+			frame->nr         = (skb->data[1] >> 1) & 0x7F;
+			frame->pf         = skb->data[1] & LAPB_EPF;
+			frame->control[0] = skb->data[0];
+			frame->control[1] = skb->data[1];
+			skb_pull(skb, 2);
+		} else if ((skb->data[0] & LAPB_U) == 1) {
+			if (!pskb_may_pull(skb, 2))
+				return -1;
+			/*
+			 * S frame - take out PF/NR
+			 */
+			frame->type       = skb->data[0] & 0x0F;
+			frame->nr         = (skb->data[1] >> 1) & 0x7F;
+			frame->pf         = skb->data[1] & LAPB_EPF;
+			frame->control[0] = skb->data[0];
+			frame->control[1] = skb->data[1];
+			skb_pull(skb, 2);
+		} else if ((skb->data[0] & LAPB_U) == 3) {
+			/*
+			 * U frame - take out PF
+			 */
+			frame->type       = skb->data[0] & ~LAPB_SPF;
+			frame->pf         = skb->data[0] & LAPB_SPF;
+			frame->control[0] = skb->data[0];
+			frame->control[1] = 0x00;
+			skb_pull(skb, 1);
+		}
+	} else {
+		if (!(skb->data[0] & LAPB_S)) {
+			/*
+			 * I frame - carries NR/NS/PF
+			 */
+			frame->type = LAPB_I;
+			frame->ns   = (skb->data[0] >> 1) & 0x07;
+			frame->nr   = (skb->data[0] >> 5) & 0x07;
+			frame->pf   = skb->data[0] & LAPB_SPF;
+		} else if ((skb->data[0] & LAPB_U) == 1) {
+			/*
+			 * S frame - take out PF/NR
+			 */
+			frame->type = skb->data[0] & 0x0F;
+			frame->nr   = (skb->data[0] >> 5) & 0x07;
+			frame->pf   = skb->data[0] & LAPB_SPF;
+		} else if ((skb->data[0] & LAPB_U) == 3) {
+			/*
+			 * U frame - take out PF
+			 */
+			frame->type = skb->data[0] & ~LAPB_SPF;
+			frame->pf   = skb->data[0] & LAPB_SPF;
+		}
+
+		frame->control[0] = skb->data[0];
+
+		skb_pull(skb, 1);
+	}
+
+	return 0;
+}
+
+/*
+ *	This routine is called when the HDLC layer internally  generates a
+ *	command or  response  for  the remote machine ( eg. RR, UA etc. ).
+ *	Only supervisory or unnumbered frames are processed, FRMRs are handled
+ *	by lapb_transmit_frmr below.
+ */
+void lapb_send_control(struct lapb_cb *lapb, int frametype,
+		       int poll_bit, int type)
+{
+	struct sk_buff *skb;
+	unsigned char  *dptr;
+
+	if ((skb = alloc_skb(LAPB_HEADER_LEN + 3, GFP_ATOMIC)) == NULL)
+		return;
+
+	skb_reserve(skb, LAPB_HEADER_LEN + 1);
+
+	if (lapb->mode & LAPB_EXTENDED) {
+		if ((frametype & LAPB_U) == LAPB_U) {
+			dptr   = skb_put(skb, 1);
+			*dptr  = frametype;
+			*dptr |= poll_bit ? LAPB_SPF : 0;
+		} else {
+			dptr     = skb_put(skb, 2);
+			dptr[0]  = frametype;
+			dptr[1]  = (lapb->vr << 1);
+			dptr[1] |= poll_bit ? LAPB_EPF : 0;
+		}
+	} else {
+		dptr   = skb_put(skb, 1);
+		*dptr  = frametype;
+		*dptr |= poll_bit ? LAPB_SPF : 0;
+		if ((frametype & LAPB_U) == LAPB_S)	/* S frames carry NR */
+			*dptr |= (lapb->vr << 5);
+	}
+
+	lapb_transmit_buffer(lapb, skb, type);
+}
+
+/*
+ *	This routine generates FRMRs based on information previously stored in
+ *	the LAPB control block.
+ */
+void lapb_transmit_frmr(struct lapb_cb *lapb)
+{
+	struct sk_buff *skb;
+	unsigned char  *dptr;
+
+	if ((skb = alloc_skb(LAPB_HEADER_LEN + 7, GFP_ATOMIC)) == NULL)
+		return;
+
+	skb_reserve(skb, LAPB_HEADER_LEN + 1);
+
+	if (lapb->mode & LAPB_EXTENDED) {
+		dptr    = skb_put(skb, 6);
+		*dptr++ = LAPB_FRMR;
+		*dptr++ = lapb->frmr_data.control[0];
+		*dptr++ = lapb->frmr_data.control[1];
+		*dptr++ = (lapb->vs << 1) & 0xFE;
+		*dptr   = (lapb->vr << 1) & 0xFE;
+		if (lapb->frmr_data.cr == LAPB_RESPONSE)
+			*dptr |= 0x01;
+		dptr++;
+		*dptr++ = lapb->frmr_type;
+
+		lapb_dbg(1, "(%p) S%d TX FRMR %5ph\n",
+			 lapb->dev, lapb->state,
+			 &skb->data[1]);
+	} else {
+		dptr    = skb_put(skb, 4);
+		*dptr++ = LAPB_FRMR;
+		*dptr++ = lapb->frmr_data.control[0];
+		*dptr   = (lapb->vs << 1) & 0x0E;
+		*dptr  |= (lapb->vr << 5) & 0xE0;
+		if (lapb->frmr_data.cr == LAPB_RESPONSE)
+			*dptr |= 0x10;
+		dptr++;
+		*dptr++ = lapb->frmr_type;
+
+		lapb_dbg(1, "(%p) S%d TX FRMR %3ph\n",
+			 lapb->dev, lapb->state, &skb->data[1]);
+	}
+
+	lapb_transmit_buffer(lapb, skb, LAPB_RESPONSE);
+}
diff --git a/net/lapb/lapb_timer.c b/net/lapb/lapb_timer.c
new file mode 100644
index 000000000..5be688690
--- /dev/null
+++ b/net/lapb/lapb_timer.c
@@ -0,0 +1,206 @@
+// 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.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#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/skbuff.h>
+#include <net/sock.h>
+#include <linux/uaccess.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <net/lapb.h>
+
+static void lapb_t1timer_expiry(struct timer_list *);
+static void lapb_t2timer_expiry(struct timer_list *);
+
+void lapb_start_t1timer(struct lapb_cb *lapb)
+{
+	del_timer(&lapb->t1timer);
+
+	lapb->t1timer.function = lapb_t1timer_expiry;
+	lapb->t1timer.expires  = jiffies + lapb->t1;
+
+	lapb->t1timer_running = true;
+	add_timer(&lapb->t1timer);
+}
+
+void lapb_start_t2timer(struct lapb_cb *lapb)
+{
+	del_timer(&lapb->t2timer);
+
+	lapb->t2timer.function = lapb_t2timer_expiry;
+	lapb->t2timer.expires  = jiffies + lapb->t2;
+
+	lapb->t2timer_running = true;
+	add_timer(&lapb->t2timer);
+}
+
+void lapb_stop_t1timer(struct lapb_cb *lapb)
+{
+	lapb->t1timer_running = false;
+	del_timer(&lapb->t1timer);
+}
+
+void lapb_stop_t2timer(struct lapb_cb *lapb)
+{
+	lapb->t2timer_running = false;
+	del_timer(&lapb->t2timer);
+}
+
+int lapb_t1timer_running(struct lapb_cb *lapb)
+{
+	return lapb->t1timer_running;
+}
+
+static void lapb_t2timer_expiry(struct timer_list *t)
+{
+	struct lapb_cb *lapb = from_timer(lapb, t, t2timer);
+
+	spin_lock_bh(&lapb->lock);
+	if (timer_pending(&lapb->t2timer)) /* A new timer has been set up */
+		goto out;
+	if (!lapb->t2timer_running) /* The timer has been stopped */
+		goto out;
+
+	if (lapb->condition & LAPB_ACK_PENDING_CONDITION) {
+		lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
+		lapb_timeout_response(lapb);
+	}
+	lapb->t2timer_running = false;
+
+out:
+	spin_unlock_bh(&lapb->lock);
+}
+
+static void lapb_t1timer_expiry(struct timer_list *t)
+{
+	struct lapb_cb *lapb = from_timer(lapb, t, t1timer);
+
+	spin_lock_bh(&lapb->lock);
+	if (timer_pending(&lapb->t1timer)) /* A new timer has been set up */
+		goto out;
+	if (!lapb->t1timer_running) /* The timer has been stopped */
+		goto out;
+
+	switch (lapb->state) {
+
+		/*
+		 *	If we are a DCE, send DM up to N2 times, then switch to
+		 *	STATE_1 and send SABM(E).
+		 */
+		case LAPB_STATE_0:
+			if (lapb->mode & LAPB_DCE &&
+			    lapb->n2count != lapb->n2) {
+				lapb->n2count++;
+				lapb_send_control(lapb, LAPB_DM, LAPB_POLLOFF, LAPB_RESPONSE);
+			} else {
+				lapb->state = LAPB_STATE_1;
+				lapb_establish_data_link(lapb);
+			}
+			break;
+
+		/*
+		 *	Awaiting connection state, send SABM(E), up to N2 times.
+		 */
+		case LAPB_STATE_1:
+			if (lapb->n2count == lapb->n2) {
+				lapb_clear_queues(lapb);
+				lapb->state = LAPB_STATE_0;
+				lapb_disconnect_indication(lapb, LAPB_TIMEDOUT);
+				lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev);
+				lapb->t1timer_running = false;
+				goto out;
+			} else {
+				lapb->n2count++;
+				if (lapb->mode & LAPB_EXTENDED) {
+					lapb_dbg(1, "(%p) S1 TX SABME(1)\n",
+						 lapb->dev);
+					lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
+				} else {
+					lapb_dbg(1, "(%p) S1 TX SABM(1)\n",
+						 lapb->dev);
+					lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
+				}
+			}
+			break;
+
+		/*
+		 *	Awaiting disconnection state, send DISC, up to N2 times.
+		 */
+		case LAPB_STATE_2:
+			if (lapb->n2count == lapb->n2) {
+				lapb_clear_queues(lapb);
+				lapb->state = LAPB_STATE_0;
+				lapb_disconnect_confirmation(lapb, LAPB_TIMEDOUT);
+				lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev);
+				lapb->t1timer_running = false;
+				goto out;
+			} else {
+				lapb->n2count++;
+				lapb_dbg(1, "(%p) S2 TX DISC(1)\n", lapb->dev);
+				lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
+			}
+			break;
+
+		/*
+		 *	Data transfer state, restransmit I frames, up to N2 times.
+		 */
+		case LAPB_STATE_3:
+			if (lapb->n2count == lapb->n2) {
+				lapb_clear_queues(lapb);
+				lapb->state = LAPB_STATE_0;
+				lapb_stop_t2timer(lapb);
+				lapb_disconnect_indication(lapb, LAPB_TIMEDOUT);
+				lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev);
+				lapb->t1timer_running = false;
+				goto out;
+			} else {
+				lapb->n2count++;
+				lapb_requeue_frames(lapb);
+				lapb_kick(lapb);
+			}
+			break;
+
+		/*
+		 *	Frame reject state, restransmit FRMR frames, up to N2 times.
+		 */
+		case LAPB_STATE_4:
+			if (lapb->n2count == lapb->n2) {
+				lapb_clear_queues(lapb);
+				lapb->state = LAPB_STATE_0;
+				lapb_disconnect_indication(lapb, LAPB_TIMEDOUT);
+				lapb_dbg(0, "(%p) S4 -> S0\n", lapb->dev);
+				lapb->t1timer_running = false;
+				goto out;
+			} else {
+				lapb->n2count++;
+				lapb_transmit_frmr(lapb);
+			}
+			break;
+	}
+
+	lapb_start_t1timer(lapb);
+
+out:
+	spin_unlock_bh(&lapb->lock);
+}