net/lapb/lapb_in.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 Naulor Started Coding
   9  *      LAPB 002        Jonathan Naylor New timer architecture.
  10  *      2000-10-29      Henner Eisen    lapb_data_indication() return status.
  11  */
  12
  13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14
  15 #include <linux/errno.h>
  16 #include <linux/types.h>
  17 #include <linux/socket.h>
  18 #include <linux/in.h>
  19 #include <linux/kernel.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/netdevice.h>
  26 #include <linux/skbuff.h>
  27 #include <linux/slab.h>
  28 #include <net/sock.h>
  29 #include <linux/uaccess.h>
  30 #include <linux/fcntl.h>
  31 #include <linux/mm.h>
  32 #include <linux/interrupt.h>
  33 #include <net/lapb.h>
  34
  35 /*
  36  *      State machine for state 0, Disconnected State.
  37  *      The handling of the timer(s) is in file lapb_timer.c.
  38  */
  39 static void lapb_state0_machine(struct lapb_cb *lapb, struct sk_buff *skb,
  40                                 struct lapb_frame *frame)
  41 {
  42         switch (frame->type) {
  43         case LAPB_SABM:
  44                 lapb_dbg(1, "(%p) S0 RX SABM(%d)\n", lapb->dev, frame->pf);
  45                 if (lapb->mode & LAPB_EXTENDED) {
  46                         lapb_dbg(1, "(%p) S0 TX DM(%d)\n",
  47                                  lapb->dev, frame->pf);
  48                         lapb_send_control(lapb, LAPB_DM, frame->pf,
  49                                           LAPB_RESPONSE);
  50                 } else {
  51                         lapb_dbg(1, "(%p) S0 TX UA(%d)\n",
  52                                  lapb->dev, frame->pf);
  53                         lapb_dbg(0, "(%p) S0 -> S3\n", lapb->dev);
  54                         lapb_send_control(lapb, LAPB_UA, frame->pf,
  55                                           LAPB_RESPONSE);
  56                         lapb_stop_t1timer(lapb);
  57                         lapb_stop_t2timer(lapb);
  58                         lapb->state     = LAPB_STATE_3;
  59                         lapb->condition = 0x00;
  60                         lapb->n2count   = 0;
  61                         lapb->vs        = 0;
  62                         lapb->vr        = 0;
  63                         lapb->va        = 0;
  64                         lapb_connect_indication(lapb, LAPB_OK);
  65                 }
  66                 break;
  67
  68         case LAPB_SABME:
  69                 lapb_dbg(1, "(%p) S0 RX SABME(%d)\n", lapb->dev, frame->pf);
  70                 if (lapb->mode & LAPB_EXTENDED) {
  71                         lapb_dbg(1, "(%p) S0 TX UA(%d)\n",
  72                                  lapb->dev, frame->pf);
  73                         lapb_dbg(0, "(%p) S0 -> S3\n", lapb->dev);
  74                         lapb_send_control(lapb, LAPB_UA, frame->pf,
  75                                           LAPB_RESPONSE);
  76                         lapb_stop_t1timer(lapb);
  77                         lapb_stop_t2timer(lapb);
  78                         lapb->state     = LAPB_STATE_3;
  79                         lapb->condition = 0x00;
  80                         lapb->n2count   = 0;
  81                         lapb->vs        = 0;
  82                         lapb->vr        = 0;
  83                         lapb->va        = 0;
  84                         lapb_connect_indication(lapb, LAPB_OK);
  85                 } else {
  86                         lapb_dbg(1, "(%p) S0 TX DM(%d)\n",
  87                                  lapb->dev, frame->pf);
  88                         lapb_send_control(lapb, LAPB_DM, frame->pf,
  89                                           LAPB_RESPONSE);
  90                 }
  91                 break;
  92
  93         case LAPB_DISC:
  94                 lapb_dbg(1, "(%p) S0 RX DISC(%d)\n", lapb->dev, frame->pf);
  95                 lapb_dbg(1, "(%p) S0 TX UA(%d)\n", lapb->dev, frame->pf);
  96                 lapb_send_control(lapb, LAPB_UA, frame->pf, LAPB_RESPONSE);
  97                 break;
  98
  99         default:
 100                 break;
 101         }
 102
 103         kfree_skb(skb);
 104 }
 105
 106 /*
 107  *      State machine for state 1, Awaiting Connection State.
 108  *      The handling of the timer(s) is in file lapb_timer.c.
 109  */
 110 static void lapb_state1_machine(struct lapb_cb *lapb, struct sk_buff *skb,
 111                                 struct lapb_frame *frame)
 112 {
 113         switch (frame->type) {
 114         case LAPB_SABM:
 115                 lapb_dbg(1, "(%p) S1 RX SABM(%d)\n", lapb->dev, frame->pf);
 116                 if (lapb->mode & LAPB_EXTENDED) {
 117                         lapb_dbg(1, "(%p) S1 TX DM(%d)\n",
 118                                  lapb->dev, frame->pf);
 119                         lapb_send_control(lapb, LAPB_DM, frame->pf,
 120                                           LAPB_RESPONSE);
 121                 } else {
 122                         lapb_dbg(1, "(%p) S1 TX UA(%d)\n",
 123                                  lapb->dev, frame->pf);
 124                         lapb_send_control(lapb, LAPB_UA, frame->pf,
 125                                           LAPB_RESPONSE);
 126                 }
 127                 break;
 128
 129         case LAPB_SABME:
 130                 lapb_dbg(1, "(%p) S1 RX SABME(%d)\n", lapb->dev, frame->pf);
 131                 if (lapb->mode & LAPB_EXTENDED) {
 132                         lapb_dbg(1, "(%p) S1 TX UA(%d)\n",
 133                                  lapb->dev, frame->pf);
 134                         lapb_send_control(lapb, LAPB_UA, frame->pf,
 135                                           LAPB_RESPONSE);
 136                 } else {
 137                         lapb_dbg(1, "(%p) S1 TX DM(%d)\n",
 138                                  lapb->dev, frame->pf);
 139                         lapb_send_control(lapb, LAPB_DM, frame->pf,
 140                                           LAPB_RESPONSE);
 141                 }
 142                 break;
 143
 144         case LAPB_DISC:
 145                 lapb_dbg(1, "(%p) S1 RX DISC(%d)\n", lapb->dev, frame->pf);
 146                 lapb_dbg(1, "(%p) S1 TX DM(%d)\n", lapb->dev, frame->pf);
 147                 lapb_send_control(lapb, LAPB_DM, frame->pf, LAPB_RESPONSE);
 148                 break;
 149
 150         case LAPB_UA:
 151                 lapb_dbg(1, "(%p) S1 RX UA(%d)\n", lapb->dev, frame->pf);
 152                 if (frame->pf) {
 153                         lapb_dbg(0, "(%p) S1 -> S3\n", lapb->dev);
 154                         lapb_stop_t1timer(lapb);
 155                         lapb_stop_t2timer(lapb);
 156                         lapb->state     = LAPB_STATE_3;
 157                         lapb->condition = 0x00;
 158                         lapb->n2count   = 0;
 159                         lapb->vs        = 0;
 160                         lapb->vr        = 0;
 161                         lapb->va        = 0;
 162                         lapb_connect_confirmation(lapb, LAPB_OK);
 163                 }
 164                 break;
 165
 166         case LAPB_DM:
 167                 lapb_dbg(1, "(%p) S1 RX DM(%d)\n", lapb->dev, frame->pf);
 168                 if (frame->pf) {
 169                         lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev);
 170                         lapb_clear_queues(lapb);
 171                         lapb->state = LAPB_STATE_0;
 172                         lapb_start_t1timer(lapb);
 173                         lapb_stop_t2timer(lapb);
 174                         lapb_disconnect_indication(lapb, LAPB_REFUSED);
 175                 }
 176                 break;
 177         }
 178
 179         kfree_skb(skb);
 180 }
 181
 182 /*
 183  *      State machine for state 2, Awaiting Release State.
 184  *      The handling of the timer(s) is in file lapb_timer.c
 185  */
 186 static void lapb_state2_machine(struct lapb_cb *lapb, struct sk_buff *skb,
 187                                 struct lapb_frame *frame)
 188 {
 189         switch (frame->type) {
 190         case LAPB_SABM:
 191         case LAPB_SABME:
 192                 lapb_dbg(1, "(%p) S2 RX {SABM,SABME}(%d)\n",
 193                          lapb->dev, frame->pf);
 194                 lapb_dbg(1, "(%p) S2 TX DM(%d)\n", lapb->dev, frame->pf);
 195                 lapb_send_control(lapb, LAPB_DM, frame->pf, LAPB_RESPONSE);
 196                 break;
 197
 198         case LAPB_DISC:
 199                 lapb_dbg(1, "(%p) S2 RX DISC(%d)\n", lapb->dev, frame->pf);
 200                 lapb_dbg(1, "(%p) S2 TX UA(%d)\n", lapb->dev, frame->pf);
 201                 lapb_send_control(lapb, LAPB_UA, frame->pf, LAPB_RESPONSE);
 202                 break;
 203
 204         case LAPB_UA:
 205                 lapb_dbg(1, "(%p) S2 RX UA(%d)\n", lapb->dev, frame->pf);
 206                 if (frame->pf) {
 207                         lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev);
 208                         lapb->state = LAPB_STATE_0;
 209                         lapb_start_t1timer(lapb);
 210                         lapb_stop_t2timer(lapb);
 211                         lapb_disconnect_confirmation(lapb, LAPB_OK);
 212                 }
 213                 break;
 214
 215         case LAPB_DM:
 216                 lapb_dbg(1, "(%p) S2 RX DM(%d)\n", lapb->dev, frame->pf);
 217                 if (frame->pf) {
 218                         lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev);
 219                         lapb->state = LAPB_STATE_0;
 220                         lapb_start_t1timer(lapb);
 221                         lapb_stop_t2timer(lapb);
 222                         lapb_disconnect_confirmation(lapb, LAPB_NOTCONNECTED);
 223                 }
 224                 break;
 225
 226         case LAPB_I:
 227         case LAPB_REJ:
 228         case LAPB_RNR:
 229         case LAPB_RR:
 230                 lapb_dbg(1, "(%p) S2 RX {I,REJ,RNR,RR}(%d)\n",
 231                        lapb->dev, frame->pf);
 232                 lapb_dbg(1, "(%p) S2 RX DM(%d)\n", lapb->dev, frame->pf);
 233                 if (frame->pf)
 234                         lapb_send_control(lapb, LAPB_DM, frame->pf,
 235                                           LAPB_RESPONSE);
 236                 break;
 237         }
 238
 239         kfree_skb(skb);
 240 }
 241
 242 /*
 243  *      State machine for state 3, Connected State.
 244  *      The handling of the timer(s) is in file lapb_timer.c
 245  */
 246 static void lapb_state3_machine(struct lapb_cb *lapb, struct sk_buff *skb,
 247                                 struct lapb_frame *frame)
 248 {
 249         int queued = 0;
 250         int modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS :
 251                                                      LAPB_SMODULUS;
 252
 253         switch (frame->type) {
 254         case LAPB_SABM:
 255                 lapb_dbg(1, "(%p) S3 RX SABM(%d)\n", lapb->dev, frame->pf);
 256                 if (lapb->mode & LAPB_EXTENDED) {
 257                         lapb_dbg(1, "(%p) S3 TX DM(%d)\n",
 258                                  lapb->dev, frame->pf);
 259                         lapb_send_control(lapb, LAPB_DM, frame->pf,
 260                                           LAPB_RESPONSE);
 261                 } else {
 262                         lapb_dbg(1, "(%p) S3 TX UA(%d)\n",
 263                                  lapb->dev, frame->pf);
 264                         lapb_send_control(lapb, LAPB_UA, frame->pf,
 265                                           LAPB_RESPONSE);
 266                         lapb_stop_t1timer(lapb);
 267                         lapb_stop_t2timer(lapb);
 268                         lapb->condition = 0x00;
 269                         lapb->n2count   = 0;
 270                         lapb->vs        = 0;
 271                         lapb->vr        = 0;
 272                         lapb->va        = 0;
 273                         lapb_requeue_frames(lapb);
 274                 }
 275                 break;
 276
 277         case LAPB_SABME:
 278                 lapb_dbg(1, "(%p) S3 RX SABME(%d)\n", lapb->dev, frame->pf);
 279                 if (lapb->mode & LAPB_EXTENDED) {
 280                         lapb_dbg(1, "(%p) S3 TX UA(%d)\n",
 281                                  lapb->dev, frame->pf);
 282                         lapb_send_control(lapb, LAPB_UA, frame->pf,
 283                                           LAPB_RESPONSE);
 284                         lapb_stop_t1timer(lapb);
 285                         lapb_stop_t2timer(lapb);
 286                         lapb->condition = 0x00;
 287                         lapb->n2count   = 0;
 288                         lapb->vs        = 0;
 289                         lapb->vr        = 0;
 290                         lapb->va        = 0;
 291                         lapb_requeue_frames(lapb);
 292                 } else {
 293                         lapb_dbg(1, "(%p) S3 TX DM(%d)\n",
 294                                  lapb->dev, frame->pf);
 295                         lapb_send_control(lapb, LAPB_DM, frame->pf,
 296                                           LAPB_RESPONSE);
 297                 }
 298                 break;
 299
 300         case LAPB_DISC:
 301                 lapb_dbg(1, "(%p) S3 RX DISC(%d)\n", lapb->dev, frame->pf);
 302                 lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev);
 303                 lapb_clear_queues(lapb);
 304                 lapb_send_control(lapb, LAPB_UA, frame->pf, LAPB_RESPONSE);
 305                 lapb_start_t1timer(lapb);
 306                 lapb_stop_t2timer(lapb);
 307                 lapb->state = LAPB_STATE_0;
 308                 lapb_disconnect_indication(lapb, LAPB_OK);
 309                 break;
 310
 311         case LAPB_DM:
 312                 lapb_dbg(1, "(%p) S3 RX DM(%d)\n", lapb->dev, frame->pf);
 313                 lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev);
 314                 lapb_clear_queues(lapb);
 315                 lapb->state = LAPB_STATE_0;
 316                 lapb_start_t1timer(lapb);
 317                 lapb_stop_t2timer(lapb);
 318                 lapb_disconnect_indication(lapb, LAPB_NOTCONNECTED);
 319                 break;
 320
 321         case LAPB_RNR:
 322                 lapb_dbg(1, "(%p) S3 RX RNR(%d) R%d\n",
 323                          lapb->dev, frame->pf, frame->nr);
 324                 lapb->condition |= LAPB_PEER_RX_BUSY_CONDITION;
 325                 lapb_check_need_response(lapb, frame->cr, frame->pf);
 326                 if (lapb_validate_nr(lapb, frame->nr)) {
 327                         lapb_check_iframes_acked(lapb, frame->nr);
 328                 } else {
 329                         lapb->frmr_data = *frame;
 330                         lapb->frmr_type = LAPB_FRMR_Z;
 331                         lapb_transmit_frmr(lapb);
 332                         lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
 333                         lapb_start_t1timer(lapb);
 334                         lapb_stop_t2timer(lapb);
 335                         lapb->state   = LAPB_STATE_4;
 336                         lapb->n2count = 0;
 337                 }
 338                 break;
 339
 340         case LAPB_RR:
 341                 lapb_dbg(1, "(%p) S3 RX RR(%d) R%d\n",
 342                          lapb->dev, frame->pf, frame->nr);
 343                 lapb->condition &= ~LAPB_PEER_RX_BUSY_CONDITION;
 344                 lapb_check_need_response(lapb, frame->cr, frame->pf);
 345                 if (lapb_validate_nr(lapb, frame->nr)) {
 346                         lapb_check_iframes_acked(lapb, frame->nr);
 347                 } else {
 348                         lapb->frmr_data = *frame;
 349                         lapb->frmr_type = LAPB_FRMR_Z;
 350                         lapb_transmit_frmr(lapb);
 351                         lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
 352                         lapb_start_t1timer(lapb);
 353                         lapb_stop_t2timer(lapb);
 354                         lapb->state   = LAPB_STATE_4;
 355                         lapb->n2count = 0;
 356                 }
 357                 break;
 358
 359         case LAPB_REJ:
 360                 lapb_dbg(1, "(%p) S3 RX REJ(%d) R%d\n",
 361                          lapb->dev, frame->pf, frame->nr);
 362                 lapb->condition &= ~LAPB_PEER_RX_BUSY_CONDITION;
 363                 lapb_check_need_response(lapb, frame->cr, frame->pf);
 364                 if (lapb_validate_nr(lapb, frame->nr)) {
 365                         lapb_frames_acked(lapb, frame->nr);
 366                         lapb_stop_t1timer(lapb);
 367                         lapb->n2count = 0;
 368                         lapb_requeue_frames(lapb);
 369                 } else {
 370                         lapb->frmr_data = *frame;
 371                         lapb->frmr_type = LAPB_FRMR_Z;
 372                         lapb_transmit_frmr(lapb);
 373                         lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
 374                         lapb_start_t1timer(lapb);
 375                         lapb_stop_t2timer(lapb);
 376                         lapb->state   = LAPB_STATE_4;
 377                         lapb->n2count = 0;
 378                 }
 379                 break;
 380
 381         case LAPB_I:
 382                 lapb_dbg(1, "(%p) S3 RX I(%d) S%d R%d\n",
 383                          lapb->dev, frame->pf, frame->ns, frame->nr);
 384                 if (!lapb_validate_nr(lapb, frame->nr)) {
 385                         lapb->frmr_data = *frame;
 386                         lapb->frmr_type = LAPB_FRMR_Z;
 387                         lapb_transmit_frmr(lapb);
 388                         lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
 389                         lapb_start_t1timer(lapb);
 390                         lapb_stop_t2timer(lapb);
 391                         lapb->state   = LAPB_STATE_4;
 392                         lapb->n2count = 0;
 393                         break;
 394                 }
 395                 if (lapb->condition & LAPB_PEER_RX_BUSY_CONDITION)
 396                         lapb_frames_acked(lapb, frame->nr);
 397                 else
 398                         lapb_check_iframes_acked(lapb, frame->nr);
 399
 400                 if (frame->ns == lapb->vr) {
 401                         int cn;
 402                         cn = lapb_data_indication(lapb, skb);
 403                         queued = 1;
 404                         /*
 405                          * If upper layer has dropped the frame, we
 406                          * basically ignore any further protocol
 407                          * processing. This will cause the peer
 408                          * to re-transmit the frame later like
 409                          * a frame lost on the wire.
 410                          */
 411                         if (cn == NET_RX_DROP) {
 412                                 pr_debug("rx congestion\n");
 413                                 break;
 414                         }
 415                         lapb->vr = (lapb->vr + 1) % modulus;
 416                         lapb->condition &= ~LAPB_REJECT_CONDITION;
 417                         if (frame->pf)
 418                                 lapb_enquiry_response(lapb);
 419                         else {
 420                                 if (!(lapb->condition &
 421                                       LAPB_ACK_PENDING_CONDITION)) {
 422                                         lapb->condition |= LAPB_ACK_PENDING_CONDITION;
 423                                         lapb_start_t2timer(lapb);
 424                                 }
 425                         }
 426                 } else {
 427                         if (lapb->condition & LAPB_REJECT_CONDITION) {
 428                                 if (frame->pf)
 429                                         lapb_enquiry_response(lapb);
 430                         } else {
 431                                 lapb_dbg(1, "(%p) S3 TX REJ(%d) R%d\n",
 432                                          lapb->dev, frame->pf, lapb->vr);
 433                                 lapb->condition |= LAPB_REJECT_CONDITION;
 434                                 lapb_send_control(lapb, LAPB_REJ, frame->pf,
 435                                                   LAPB_RESPONSE);
 436                                 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
 437                         }
 438                 }
 439                 break;
 440
 441         case LAPB_FRMR:
 442                 lapb_dbg(1, "(%p) S3 RX FRMR(%d) %5ph\n",
 443                          lapb->dev, frame->pf,
 444                          skb->data);
 445                 lapb_establish_data_link(lapb);
 446                 lapb_dbg(0, "(%p) S3 -> S1\n", lapb->dev);
 447                 lapb_requeue_frames(lapb);
 448                 lapb->state = LAPB_STATE_1;
 449                 break;
 450
 451         case LAPB_ILLEGAL:
 452                 lapb_dbg(1, "(%p) S3 RX ILLEGAL(%d)\n", lapb->dev, frame->pf);
 453                 lapb->frmr_data = *frame;
 454                 lapb->frmr_type = LAPB_FRMR_W;
 455                 lapb_transmit_frmr(lapb);
 456                 lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
 457                 lapb_start_t1timer(lapb);
 458                 lapb_stop_t2timer(lapb);
 459                 lapb->state   = LAPB_STATE_4;
 460                 lapb->n2count = 0;
 461                 break;
 462         }
 463
 464         if (!queued)
 465                 kfree_skb(skb);
 466 }
 467
 468 /*
 469  *      State machine for state 4, Frame Reject State.
 470  *      The handling of the timer(s) is in file lapb_timer.c.
 471  */
 472 static void lapb_state4_machine(struct lapb_cb *lapb, struct sk_buff *skb,
 473                                 struct lapb_frame *frame)
 474 {
 475         switch (frame->type) {
 476         case LAPB_SABM:
 477                 lapb_dbg(1, "(%p) S4 RX SABM(%d)\n", lapb->dev, frame->pf);
 478                 if (lapb->mode & LAPB_EXTENDED) {
 479                         lapb_dbg(1, "(%p) S4 TX DM(%d)\n",
 480                                  lapb->dev, frame->pf);
 481                         lapb_send_control(lapb, LAPB_DM, frame->pf,
 482                                           LAPB_RESPONSE);
 483                 } else {
 484                         lapb_dbg(1, "(%p) S4 TX UA(%d)\n",
 485                                  lapb->dev, frame->pf);
 486                         lapb_dbg(0, "(%p) S4 -> S3\n", lapb->dev);
 487                         lapb_send_control(lapb, LAPB_UA, frame->pf,
 488                                           LAPB_RESPONSE);
 489                         lapb_stop_t1timer(lapb);
 490                         lapb_stop_t2timer(lapb);
 491                         lapb->state     = LAPB_STATE_3;
 492                         lapb->condition = 0x00;
 493                         lapb->n2count   = 0;
 494                         lapb->vs        = 0;
 495                         lapb->vr        = 0;
 496                         lapb->va        = 0;
 497                         lapb_connect_indication(lapb, LAPB_OK);
 498                 }
 499                 break;
 500
 501         case LAPB_SABME:
 502                 lapb_dbg(1, "(%p) S4 RX SABME(%d)\n", lapb->dev, frame->pf);
 503                 if (lapb->mode & LAPB_EXTENDED) {
 504                         lapb_dbg(1, "(%p) S4 TX UA(%d)\n",
 505                                  lapb->dev, frame->pf);
 506                         lapb_dbg(0, "(%p) S4 -> S3\n", lapb->dev);
 507                         lapb_send_control(lapb, LAPB_UA, frame->pf,
 508                                           LAPB_RESPONSE);
 509                         lapb_stop_t1timer(lapb);
 510                         lapb_stop_t2timer(lapb);
 511                         lapb->state     = LAPB_STATE_3;
 512                         lapb->condition = 0x00;
 513                         lapb->n2count   = 0;
 514                         lapb->vs        = 0;
 515                         lapb->vr        = 0;
 516                         lapb->va        = 0;
 517                         lapb_connect_indication(lapb, LAPB_OK);
 518                 } else {
 519                         lapb_dbg(1, "(%p) S4 TX DM(%d)\n",
 520                                  lapb->dev, frame->pf);
 521                         lapb_send_control(lapb, LAPB_DM, frame->pf,
 522                                           LAPB_RESPONSE);
 523                 }
 524                 break;
 525         }
 526
 527         kfree_skb(skb);
 528 }
 529
 530 /*
 531  *      Process an incoming LAPB frame
 532  */
 533 void lapb_data_input(struct lapb_cb *lapb, struct sk_buff *skb)
 534 {
 535         struct lapb_frame frame;
 536
 537         if (lapb_decode(lapb, skb, &frame) < 0) {
 538                 kfree_skb(skb);
 539                 return;
 540         }
 541
 542         switch (lapb->state) {
 543         case LAPB_STATE_0:
 544                 lapb_state0_machine(lapb, skb, &frame); break;
 545         case LAPB_STATE_1:
 546                 lapb_state1_machine(lapb, skb, &frame); break;
 547         case LAPB_STATE_2:
 548                 lapb_state2_machine(lapb, skb, &frame); break;
 549         case LAPB_STATE_3:
 550                 lapb_state3_machine(lapb, skb, &frame); break;
 551         case LAPB_STATE_4:
 552                 lapb_state4_machine(lapb, skb, &frame); break;
 553         }
 554
 555         lapb_kick(lapb);
 556 }