Impressum lapb_timer.c   Sprache: C

// 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)
{
 timer_delete(&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)
{
 timer_delete(&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;
 timer_delete(&lapb->t1timer);
}

void lapb_stop_t2timer(struct lapb_cb *lapb)
{
 lapb->t2timer_running = false;
 timer_delete(&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 = timer_container_of(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 = timer_container_of(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);
}