net/lapb/lapb_timer.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      LAPB release 002
   4  *
   5  *      This code REQUIRES 2.1.15 or higher/ NET3.038
   6  *
   7  *      History
   8  *      LAPB 001        Jonathan Naylor Started Coding
   9  *      LAPB 002        Jonathan Naylor New timer architecture.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/errno.h>
  15 #include <linux/types.h>
  16 #include <linux/socket.h>
  17 #include <linux/in.h>
  18 #include <linux/kernel.h>
  19 #include <linux/jiffies.h>
  20 #include <linux/timer.h>
  21 #include <linux/string.h>
  22 #include <linux/sockios.h>
  23 #include <linux/net.h>
  24 #include <linux/inet.h>
  25 #include <linux/skbuff.h>
  26 #include <net/sock.h>
  27 #include <linux/uaccess.h>
  28 #include <linux/fcntl.h>
  29 #include <linux/mm.h>
  30 #include <linux/interrupt.h>
  31 #include <net/lapb.h>
  32
  33 static void lapb_t1timer_expiry(struct timer_list *);
  34 static void lapb_t2timer_expiry(struct timer_list *);
  35
  36 void lapb_start_t1timer(struct lapb_cb *lapb)
  37 {
  38         del_timer(&lapb->t1timer);
  39
  40         lapb->t1timer.function = lapb_t1timer_expiry;
  41         lapb->t1timer.expires  = jiffies + lapb->t1;
  42
  43         lapb->t1timer_running = true;
  44         add_timer(&lapb->t1timer);
  45 }
  46
  47 void lapb_start_t2timer(struct lapb_cb *lapb)
  48 {
  49         del_timer(&lapb->t2timer);
  50
  51         lapb->t2timer.function = lapb_t2timer_expiry;
  52         lapb->t2timer.expires  = jiffies + lapb->t2;
  53
  54         lapb->t2timer_running = true;
  55         add_timer(&lapb->t2timer);
  56 }
  57
  58 void lapb_stop_t1timer(struct lapb_cb *lapb)
  59 {
  60         lapb->t1timer_running = false;
  61         del_timer(&lapb->t1timer);
  62 }
  63
  64 void lapb_stop_t2timer(struct lapb_cb *lapb)
  65 {
  66         lapb->t2timer_running = false;
  67         del_timer(&lapb->t2timer);
  68 }
  69
  70 int lapb_t1timer_running(struct lapb_cb *lapb)
  71 {
  72         return lapb->t1timer_running;
  73 }
  74
  75 static void lapb_t2timer_expiry(struct timer_list *t)
  76 {
  77         struct lapb_cb *lapb = from_timer(lapb, t, t2timer);
  78
  79         spin_lock_bh(&lapb->lock);
  80         if (timer_pending(&lapb->t2timer)) /* A new timer has been set up */
  81                 goto out;
  82         if (!lapb->t2timer_running) /* The timer has been stopped */
  83                 goto out;
  84
  85         if (lapb->condition & LAPB_ACK_PENDING_CONDITION) {
  86                 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
  87                 lapb_timeout_response(lapb);
  88         }
  89         lapb->t2timer_running = false;
  90
  91 out:
  92         spin_unlock_bh(&lapb->lock);
  93 }
  94
  95 static void lapb_t1timer_expiry(struct timer_list *t)
  96 {
  97         struct lapb_cb *lapb = from_timer(lapb, t, t1timer);
  98
  99         spin_lock_bh(&lapb->lock);
 100         if (timer_pending(&lapb->t1timer)) /* A new timer has been set up */
 101                 goto out;
 102         if (!lapb->t1timer_running) /* The timer has been stopped */
 103                 goto out;
 104
 105         switch (lapb->state) {
 106
 107                 /*
 108                  *      If we are a DCE, send DM up to N2 times, then switch to
 109                  *      STATE_1 and send SABM(E).
 110                  */
 111                 case LAPB_STATE_0:
 112                         if (lapb->mode & LAPB_DCE &&
 113                             lapb->n2count != lapb->n2) {
 114                                 lapb->n2count++;
 115                                 lapb_send_control(lapb, LAPB_DM, LAPB_POLLOFF, LAPB_RESPONSE);
 116                         } else {
 117                                 lapb->state = LAPB_STATE_1;
 118                                 lapb_establish_data_link(lapb);
 119                         }
 120                         break;
 121
 122                 /*
 123                  *      Awaiting connection state, send SABM(E), up to N2 times.
 124                  */
 125                 case LAPB_STATE_1:
 126                         if (lapb->n2count == lapb->n2) {
 127                                 lapb_clear_queues(lapb);
 128                                 lapb->state = LAPB_STATE_0;
 129                                 lapb_disconnect_indication(lapb, LAPB_TIMEDOUT);
 130                                 lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev);
 131                                 lapb->t1timer_running = false;
 132                                 goto out;
 133                         } else {
 134                                 lapb->n2count++;
 135                                 if (lapb->mode & LAPB_EXTENDED) {
 136                                         lapb_dbg(1, "(%p) S1 TX SABME(1)\n",
 137                                                  lapb->dev);
 138                                         lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
 139                                 } else {
 140                                         lapb_dbg(1, "(%p) S1 TX SABM(1)\n",
 141                                                  lapb->dev);
 142                                         lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
 143                                 }
 144                         }
 145                         break;
 146
 147                 /*
 148                  *      Awaiting disconnection state, send DISC, up to N2 times.
 149                  */
 150                 case LAPB_STATE_2:
 151                         if (lapb->n2count == lapb->n2) {
 152                                 lapb_clear_queues(lapb);
 153                                 lapb->state = LAPB_STATE_0;
 154                                 lapb_disconnect_confirmation(lapb, LAPB_TIMEDOUT);
 155                                 lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev);
 156                                 lapb->t1timer_running = false;
 157                                 goto out;
 158                         } else {
 159                                 lapb->n2count++;
 160                                 lapb_dbg(1, "(%p) S2 TX DISC(1)\n", lapb->dev);
 161                                 lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
 162                         }
 163                         break;
 164
 165                 /*
 166                  *      Data transfer state, restransmit I frames, up to N2 times.
 167                  */
 168                 case LAPB_STATE_3:
 169                         if (lapb->n2count == lapb->n2) {
 170                                 lapb_clear_queues(lapb);
 171                                 lapb->state = LAPB_STATE_0;
 172                                 lapb_stop_t2timer(lapb);
 173                                 lapb_disconnect_indication(lapb, LAPB_TIMEDOUT);
 174                                 lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev);
 175                                 lapb->t1timer_running = false;
 176                                 goto out;
 177                         } else {
 178                                 lapb->n2count++;
 179                                 lapb_requeue_frames(lapb);
 180                                 lapb_kick(lapb);
 181                         }
 182                         break;
 183
 184                 /*
 185                  *      Frame reject state, restransmit FRMR frames, up to N2 times.
 186                  */
 187                 case LAPB_STATE_4:
 188                         if (lapb->n2count == lapb->n2) {
 189                                 lapb_clear_queues(lapb);
 190                                 lapb->state = LAPB_STATE_0;
 191                                 lapb_disconnect_indication(lapb, LAPB_TIMEDOUT);
 192                                 lapb_dbg(0, "(%p) S4 -> S0\n", lapb->dev);
 193                                 lapb->t1timer_running = false;
 194                                 goto out;
 195                         } else {
 196                                 lapb->n2count++;
 197                                 lapb_transmit_frmr(lapb);
 198                         }
 199                         break;
 200         }
 201
 202         lapb_start_t1timer(lapb);
 203
 204 out:
 205         spin_unlock_bh(&lapb->lock);
 206 }