lapb_timer.c

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/*
 *  LAPB release 002
 *
 *  This code REQUIRES 2.1.15 or higher/ NET3.038
 *
 *  This module:
 *      This module is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 *  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 <asm/uaccess.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <net/lapb.h>

static void lapb_t1timer_expiry(unsigned long);
static void lapb_t2timer_expiry(unsigned long);

void lapb_start_t1timer(struct lapb_cb *lapb)
{
    del_timer(&lapb->t1timer);

    lapb->t1timer.data     = (unsigned long)lapb;
    lapb->t1timer.function = &lapb_t1timer_expiry;
    lapb->t1timer.expires  = jiffies + lapb->t1;

    add_timer(&lapb->t1timer);
}

void lapb_start_t2timer(struct lapb_cb *lapb)
{
    del_timer(&lapb->t2timer);

    lapb->t2timer.data     = (unsigned long)lapb;
    lapb->t2timer.function = &lapb_t2timer_expiry;
    lapb->t2timer.expires  = jiffies + lapb->t2;

    add_timer(&lapb->t2timer);
}

void lapb_stop_t1timer(struct lapb_cb *lapb)
{
    del_timer(&lapb->t1timer);
}

void lapb_stop_t2timer(struct lapb_cb *lapb)
{
    del_timer(&lapb->t2timer);
}

int lapb_t1timer_running(struct lapb_cb *lapb)
{
    return timer_pending(&lapb->t1timer);
}

static void lapb_t2timer_expiry(unsigned long param)
{
    struct lapb_cb *lapb = (struct lapb_cb *)param;

    if (lapb->condition & LAPB_ACK_PENDING_CONDITION) {
        lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
        lapb_timeout_response(lapb);
    }
}

static void lapb_t1timer_expiry(unsigned long param)
{
    struct lapb_cb *lapb = (struct lapb_cb *)param;

    switch (lapb->state) {

        /*
         *  If we are a DCE, keep going DM .. DM .. DM
         */
        case LAPB_STATE_0:
            if (lapb->mode & LAPB_DCE)
                lapb_send_control(lapb, LAPB_DM, LAPB_POLLOFF, LAPB_RESPONSE);
            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);
                return;
            } 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);
                return;
            } 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);
                return;
            } else {
                lapb->n2count++;
                lapb_requeue_frames(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);
                return;
            } else {
                lapb->n2count++;
                lapb_transmit_frmr(lapb);
            }
            break;
    }

    lapb_start_t1timer(lapb);
}