net/llc/llc_station.c

   1 /*
   2  * llc_station.c - station component of LLC
   3  *
   4  * Copyright (c) 1997 by Procom Technology, Inc.
   5  *               2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   6  *
   7  * This program can be redistributed or modified under the terms of the
   8  * GNU General Public License as published by the Free Software Foundation.
   9  * This program is distributed without any warranty or implied warranty
  10  * of merchantability or fitness for a particular purpose.
  11  *
  12  * See the GNU General Public License for more details.
  13  */
  14 #include <linux/config.h>
  15 #include <linux/init.h>
  16 #include <linux/module.h>
  17 #include <net/llc.h>
  18 #include <net/llc_sap.h>
  19 #include <net/llc_conn.h>
  20 #include <net/llc_c_ac.h>
  21 #include <net/llc_s_ac.h>
  22 #include <net/llc_c_ev.h>
  23 #include <net/llc_c_st.h>
  24 #include <net/llc_s_ev.h>
  25 #include <net/llc_s_st.h>
  26 #include <net/llc_pdu.h>
  27
  28 /**
  29  * struct llc_station - LLC station component
  30  *
  31  * SAP and connection resource manager, one per adapter.
  32  *
  33  * @state - state of station
  34  * @xid_r_count - XID response PDU counter
  35  * @mac_sa - MAC source address
  36  * @sap_list - list of related SAPs
  37  * @ev_q - events entering state mach.
  38  * @mac_pdu_q - PDUs ready to send to MAC
  39  */
  40 struct llc_station {
  41         u8                          state;
  42         u8                          xid_r_count;
  43         struct timer_list           ack_timer;
  44         u8                          retry_count;
  45         u8                          maximum_retry;
  46         struct {
  47                 struct sk_buff_head list;
  48                 spinlock_t          lock;
  49         } ev_q;
  50         struct sk_buff_head         mac_pdu_q;
  51 };
  52
  53 /* Types of events (possible values in 'ev->type') */
  54 #define LLC_STATION_EV_TYPE_SIMPLE      1
  55 #define LLC_STATION_EV_TYPE_CONDITION   2
  56 #define LLC_STATION_EV_TYPE_PRIM        3
  57 #define LLC_STATION_EV_TYPE_PDU         4       /* command/response PDU */
  58 #define LLC_STATION_EV_TYPE_ACK_TMR     5
  59 #define LLC_STATION_EV_TYPE_RPT_STATUS  6
  60
  61 /* Events */
  62 #define LLC_STATION_EV_ENABLE_WITH_DUP_ADDR_CHECK               1
  63 #define LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK            2
  64 #define LLC_STATION_EV_ACK_TMR_EXP_LT_RETRY_CNT_MAX_RETRY       3
  65 #define LLC_STATION_EV_ACK_TMR_EXP_EQ_RETRY_CNT_MAX_RETRY       4
  66 #define LLC_STATION_EV_RX_NULL_DSAP_XID_C                       5
  67 #define LLC_STATION_EV_RX_NULL_DSAP_0_XID_R_XID_R_CNT_EQ        6
  68 #define LLC_STATION_EV_RX_NULL_DSAP_1_XID_R_XID_R_CNT_EQ        7
  69 #define LLC_STATION_EV_RX_NULL_DSAP_TEST_C                      8
  70 #define LLC_STATION_EV_DISABLE_REQ                              9
  71
  72 struct llc_station_state_ev {
  73         u8               type;
  74         u8               prim;
  75         u8               prim_type;
  76         u8               reason;
  77         struct list_head node; /* node in station->ev_q.list */
  78 };
  79
  80 static __inline__ struct llc_station_state_ev *
  81                                         llc_station_ev(struct sk_buff *skb)
  82 {
  83         return (struct llc_station_state_ev *)skb->cb;
  84 }
  85
  86 typedef int (*llc_station_ev_t)(struct sk_buff *skb);
  87
  88 #define LLC_STATION_STATE_DOWN          1       /* initial state */
  89 #define LLC_STATION_STATE_DUP_ADDR_CHK  2
  90 #define LLC_STATION_STATE_UP            3
  91
  92 #define LLC_NBR_STATION_STATES          3       /* size of state table */
  93
  94 typedef int (*llc_station_action_t)(struct sk_buff *skb);
  95
  96 /* Station component state table structure */
  97 struct llc_station_state_trans {
  98         llc_station_ev_t ev;
  99         u8 next_state;
 100         llc_station_action_t *ev_actions;
 101 };
 102
 103 struct llc_station_state {
 104         u8 curr_state;
 105         struct llc_station_state_trans **transitions;
 106 };
 107
 108 static struct llc_station llc_main_station;
 109
 110 static int llc_stat_ev_enable_with_dup_addr_check(struct sk_buff *skb)
 111 {
 112         struct llc_station_state_ev *ev = llc_station_ev(skb);
 113
 114         return ev->type == LLC_STATION_EV_TYPE_SIMPLE &&
 115                ev->prim_type ==
 116                               LLC_STATION_EV_ENABLE_WITH_DUP_ADDR_CHECK ? 0 : 1;
 117 }
 118
 119 static int llc_stat_ev_enable_without_dup_addr_check(struct sk_buff *skb)
 120 {
 121         struct llc_station_state_ev *ev = llc_station_ev(skb);
 122
 123         return ev->type == LLC_STATION_EV_TYPE_SIMPLE &&
 124                ev->prim_type ==
 125                         LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK ? 0 : 1;
 126 }
 127
 128 static int llc_stat_ev_ack_tmr_exp_lt_retry_cnt_max_retry(struct sk_buff *skb)
 129 {
 130         struct llc_station_state_ev *ev = llc_station_ev(skb);
 131
 132         return ev->type == LLC_STATION_EV_TYPE_ACK_TMR &&
 133                 llc_main_station.retry_count <
 134                 llc_main_station.maximum_retry ? 0 : 1;
 135 }
 136
 137 static int llc_stat_ev_ack_tmr_exp_eq_retry_cnt_max_retry(struct sk_buff *skb)
 138 {
 139         struct llc_station_state_ev *ev = llc_station_ev(skb);
 140
 141         return ev->type == LLC_STATION_EV_TYPE_ACK_TMR &&
 142                 llc_main_station.retry_count ==
 143                 llc_main_station.maximum_retry ? 0 : 1;
 144 }
 145
 146 static int llc_stat_ev_rx_null_dsap_xid_c(struct sk_buff *skb)
 147 {
 148         struct llc_station_state_ev *ev = llc_station_ev(skb);
 149         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
 150
 151         return ev->type == LLC_STATION_EV_TYPE_PDU &&
 152                LLC_PDU_IS_CMD(pdu) &&                   /* command PDU */
 153                LLC_PDU_TYPE_IS_U(pdu) &&                /* U type PDU */
 154                LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_XID &&
 155                !pdu->dsap ? 0 : 1;                      /* NULL DSAP value */
 156 }
 157
 158 static int llc_stat_ev_rx_null_dsap_0_xid_r_xid_r_cnt_eq(struct sk_buff *skb)
 159 {
 160         struct llc_station_state_ev *ev = llc_station_ev(skb);
 161         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
 162
 163         return ev->type == LLC_STATION_EV_TYPE_PDU &&
 164                LLC_PDU_IS_RSP(pdu) &&                   /* response PDU */
 165                LLC_PDU_TYPE_IS_U(pdu) &&                /* U type PDU */
 166                LLC_U_PDU_RSP(pdu) == LLC_1_PDU_CMD_XID &&
 167                !pdu->dsap &&                            /* NULL DSAP value */
 168                !llc_main_station.xid_r_count ? 0 : 1;
 169 }
 170
 171 static int llc_stat_ev_rx_null_dsap_1_xid_r_xid_r_cnt_eq(struct sk_buff *skb)
 172 {
 173         struct llc_station_state_ev *ev = llc_station_ev(skb);
 174         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
 175
 176         return ev->type == LLC_STATION_EV_TYPE_PDU &&
 177                LLC_PDU_IS_RSP(pdu) &&                   /* response PDU */
 178                LLC_PDU_TYPE_IS_U(pdu) &&                /* U type PDU */
 179                LLC_U_PDU_RSP(pdu) == LLC_1_PDU_CMD_XID &&
 180                !pdu->dsap &&                            /* NULL DSAP value */
 181                llc_main_station.xid_r_count == 1 ? 0 : 1;
 182 }
 183
 184 static int llc_stat_ev_rx_null_dsap_test_c(struct sk_buff *skb)
 185 {
 186         struct llc_station_state_ev *ev = llc_station_ev(skb);
 187         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
 188
 189         return ev->type == LLC_STATION_EV_TYPE_PDU &&
 190                LLC_PDU_IS_CMD(pdu) &&                   /* command PDU */
 191                LLC_PDU_TYPE_IS_U(pdu) &&                /* U type PDU */
 192                LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_TEST &&
 193                !pdu->dsap ? 0 : 1;                      /* NULL DSAP */
 194 }
 195
 196 static int llc_stat_ev_disable_req(struct sk_buff *skb)
 197 {
 198         struct llc_station_state_ev *ev = llc_station_ev(skb);
 199
 200         return ev->type == LLC_STATION_EV_TYPE_PRIM &&
 201                ev->prim == LLC_DISABLE_PRIM &&
 202                ev->prim_type == LLC_PRIM_TYPE_REQ ? 0 : 1;
 203 }
 204
 205 /**
 206  *      llc_station_send_pdu - queues PDU to send
 207  *      @skb: Address of the PDU
 208  *
 209  *      Queues a PDU to send to the MAC layer.
 210  */
 211 static void llc_station_send_pdu(struct sk_buff *skb)
 212 {
 213         skb_queue_tail(&llc_main_station.mac_pdu_q, skb);
 214         while ((skb = skb_dequeue(&llc_main_station.mac_pdu_q)) != NULL)
 215                 if (dev_queue_xmit(skb))
 216                         break;
 217 }
 218
 219 static int llc_station_ac_start_ack_timer(struct sk_buff *skb)
 220 {
 221         mod_timer(&llc_main_station.ack_timer, jiffies + LLC_ACK_TIME * HZ);
 222         return 0;
 223 }
 224
 225 static int llc_station_ac_set_retry_cnt_0(struct sk_buff *skb)
 226 {
 227         llc_main_station.retry_count = 0;
 228         return 0;
 229 }
 230
 231 static int llc_station_ac_inc_retry_cnt_by_1(struct sk_buff *skb)
 232 {
 233         llc_main_station.retry_count++;
 234         return 0;
 235 }
 236
 237 static int llc_station_ac_set_xid_r_cnt_0(struct sk_buff *skb)
 238 {
 239         llc_main_station.xid_r_count = 0;
 240         return 0;
 241 }
 242
 243 static int llc_station_ac_inc_xid_r_cnt_by_1(struct sk_buff *skb)
 244 {
 245         llc_main_station.xid_r_count++;
 246         return 0;
 247 }
 248
 249 static int llc_station_ac_send_null_dsap_xid_c(struct sk_buff *skb)
 250 {
 251         int rc = 1;
 252         struct sk_buff *nskb = llc_alloc_frame();
 253
 254         if (!nskb)
 255                 goto out;
 256         llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, 0, LLC_PDU_CMD);
 257         llc_pdu_init_as_xid_cmd(nskb, LLC_XID_NULL_CLASS_2, 127);
 258         rc = llc_mac_hdr_init(nskb, llc_station_mac_sa, llc_station_mac_sa);
 259         if (rc)
 260                 goto free;
 261         llc_station_send_pdu(nskb);
 262 out:
 263         return rc;
 264 free:
 265         kfree_skb(skb);
 266         goto out;
 267 }
 268
 269 static int llc_station_ac_send_xid_r(struct sk_buff *skb)
 270 {
 271         u8 mac_da[ETH_ALEN], dsap;
 272         int rc = 1;
 273         struct sk_buff* nskb = llc_alloc_frame();
 274
 275         if (!nskb)
 276                 goto out;
 277         rc = 0;
 278         nskb->dev = skb->dev;
 279         llc_pdu_decode_sa(skb, mac_da);
 280         llc_pdu_decode_ssap(skb, &dsap);
 281         llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
 282         llc_pdu_init_as_xid_rsp(nskb, LLC_XID_NULL_CLASS_2, 127);
 283         rc = llc_mac_hdr_init(nskb, llc_station_mac_sa, mac_da);
 284         if (rc)
 285                 goto free;
 286         llc_station_send_pdu(nskb);
 287 out:
 288         return rc;
 289 free:
 290         kfree_skb(skb);
 291         goto out;
 292 }
 293
 294 static int llc_station_ac_send_test_r(struct sk_buff *skb)
 295 {
 296         u8 mac_da[ETH_ALEN], dsap;
 297         int rc = 1;
 298         struct sk_buff *nskb = llc_alloc_frame();
 299
 300         if (!nskb)
 301                 goto out;
 302         rc = 0;
 303         nskb->dev = skb->dev;
 304         llc_pdu_decode_sa(skb, mac_da);
 305         llc_pdu_decode_ssap(skb, &dsap);
 306         llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
 307         llc_pdu_init_as_test_rsp(nskb, skb);
 308         rc = llc_mac_hdr_init(nskb, llc_station_mac_sa, mac_da);
 309         if (rc)
 310                 goto free;
 311         llc_station_send_pdu(nskb);
 312 out:
 313         return rc;
 314 free:
 315         kfree_skb(skb);
 316         goto out;
 317 }
 318
 319 static int llc_station_ac_report_status(struct sk_buff *skb)
 320 {
 321         return 0;
 322 }
 323
 324 /* COMMON STATION STATE transitions */
 325
 326 /* dummy last-transition indicator; common to all state transition groups
 327  * last entry for this state
 328  * all members are zeros, .bss zeroes it
 329  */
 330 static struct llc_station_state_trans llc_stat_state_trans_end;
 331
 332 /* DOWN STATE transitions */
 333
 334 /* state transition for LLC_STATION_EV_ENABLE_WITH_DUP_ADDR_CHECK event */
 335 static llc_station_action_t llc_stat_down_state_actions_1[] = {
 336         [0] = llc_station_ac_start_ack_timer,
 337         [1] = llc_station_ac_set_retry_cnt_0,
 338         [2] = llc_station_ac_set_xid_r_cnt_0,
 339         [3] = llc_station_ac_send_null_dsap_xid_c,
 340         [4] = NULL,
 341 };
 342
 343 static struct llc_station_state_trans llc_stat_down_state_trans_1 = {
 344         .ev         = llc_stat_ev_enable_with_dup_addr_check,
 345         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
 346         .ev_actions = llc_stat_down_state_actions_1,
 347 };
 348
 349 /* state transition for LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK event */
 350 static llc_station_action_t llc_stat_down_state_actions_2[] = {
 351         [0] = llc_station_ac_report_status,     /* STATION UP */
 352         [1] = NULL,
 353 };
 354
 355 static struct llc_station_state_trans llc_stat_down_state_trans_2 = {
 356         .ev         = llc_stat_ev_enable_without_dup_addr_check,
 357         .next_state = LLC_STATION_STATE_UP,
 358         .ev_actions = llc_stat_down_state_actions_2,
 359 };
 360
 361 /* array of pointers; one to each transition */
 362 static struct llc_station_state_trans *llc_stat_dwn_state_trans[] = {
 363         [0] = &llc_stat_down_state_trans_1,
 364         [1] = &llc_stat_down_state_trans_2,
 365         [2] = &llc_stat_state_trans_end,
 366 };
 367
 368 /* UP STATE transitions */
 369 /* state transition for LLC_STATION_EV_DISABLE_REQ event */
 370 static llc_station_action_t llc_stat_up_state_actions_1[] = {
 371         [0] = llc_station_ac_report_status,     /* STATION DOWN */
 372         [1] = NULL,
 373 };
 374
 375 static struct llc_station_state_trans llc_stat_up_state_trans_1 = {
 376         .ev         = llc_stat_ev_disable_req,
 377         .next_state = LLC_STATION_STATE_DOWN,
 378         .ev_actions = llc_stat_up_state_actions_1,
 379 };
 380
 381 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_XID_C event */
 382 static llc_station_action_t llc_stat_up_state_actions_2[] = {
 383         [0] = llc_station_ac_send_xid_r,
 384         [1] = NULL,
 385 };
 386
 387 static struct llc_station_state_trans llc_stat_up_state_trans_2 = {
 388         .ev         = llc_stat_ev_rx_null_dsap_xid_c,
 389         .next_state = LLC_STATION_STATE_UP,
 390         .ev_actions = llc_stat_up_state_actions_2,
 391 };
 392
 393 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_TEST_C event */
 394 static llc_station_action_t llc_stat_up_state_actions_3[] = {
 395         [0] = llc_station_ac_send_test_r,
 396         [1] = NULL,
 397 };
 398
 399 static struct llc_station_state_trans llc_stat_up_state_trans_3 = {
 400         .ev         = llc_stat_ev_rx_null_dsap_test_c,
 401         .next_state = LLC_STATION_STATE_UP,
 402         .ev_actions = llc_stat_up_state_actions_3,
 403 };
 404
 405 /* array of pointers; one to each transition */
 406 static struct llc_station_state_trans *llc_stat_up_state_trans [] = {
 407         [0] = &llc_stat_up_state_trans_1,
 408         [1] = &llc_stat_up_state_trans_2,
 409         [2] = &llc_stat_up_state_trans_3,
 410         [3] = &llc_stat_state_trans_end,
 411 };
 412
 413 /* DUP ADDR CHK STATE transitions */
 414 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_0_XID_R_XID_R_CNT_EQ
 415  * event
 416  */
 417 static llc_station_action_t llc_stat_dupaddr_state_actions_1[] = {
 418         [0] = llc_station_ac_inc_xid_r_cnt_by_1,
 419         [1] = NULL,
 420 };
 421
 422 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_1 = {
 423         .ev         = llc_stat_ev_rx_null_dsap_0_xid_r_xid_r_cnt_eq,
 424         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
 425         .ev_actions = llc_stat_dupaddr_state_actions_1,
 426 };
 427
 428 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_1_XID_R_XID_R_CNT_EQ
 429  * event
 430  */
 431 static llc_station_action_t llc_stat_dupaddr_state_actions_2[] = {
 432         [0] = llc_station_ac_report_status,     /* DUPLICATE ADDRESS FOUND */
 433         [1] = NULL,
 434 };
 435
 436 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_2 = {
 437         .ev         = llc_stat_ev_rx_null_dsap_1_xid_r_xid_r_cnt_eq,
 438         .next_state = LLC_STATION_STATE_DOWN,
 439         .ev_actions = llc_stat_dupaddr_state_actions_2,
 440 };
 441
 442 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_XID_C event */
 443 static llc_station_action_t llc_stat_dupaddr_state_actions_3[] = {
 444         [0] = llc_station_ac_send_xid_r,
 445         [1] = NULL,
 446 };
 447
 448 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_3 = {
 449         .ev         = llc_stat_ev_rx_null_dsap_xid_c,
 450         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
 451         .ev_actions = llc_stat_dupaddr_state_actions_3,
 452 };
 453
 454 /* state transition for LLC_STATION_EV_ACK_TMR_EXP_LT_RETRY_CNT_MAX_RETRY
 455  * event
 456  */
 457 static llc_station_action_t llc_stat_dupaddr_state_actions_4[] = {
 458         [0] = llc_station_ac_start_ack_timer,
 459         [1] = llc_station_ac_inc_retry_cnt_by_1,
 460         [2] = llc_station_ac_set_xid_r_cnt_0,
 461         [3] = llc_station_ac_send_null_dsap_xid_c,
 462         [4] = NULL,
 463 };
 464
 465 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_4 = {
 466         .ev         = llc_stat_ev_ack_tmr_exp_lt_retry_cnt_max_retry,
 467         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
 468         .ev_actions = llc_stat_dupaddr_state_actions_4,
 469 };
 470
 471 /* state transition for LLC_STATION_EV_ACK_TMR_EXP_EQ_RETRY_CNT_MAX_RETRY
 472  * event
 473  */
 474 static llc_station_action_t llc_stat_dupaddr_state_actions_5[] = {
 475         [0] = llc_station_ac_report_status,     /* STATION UP */
 476         [1] = NULL,
 477 };
 478
 479 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_5 = {
 480         .ev         = llc_stat_ev_ack_tmr_exp_eq_retry_cnt_max_retry,
 481         .next_state = LLC_STATION_STATE_UP,
 482         .ev_actions = llc_stat_dupaddr_state_actions_5,
 483 };
 484
 485 /* state transition for LLC_STATION_EV_DISABLE_REQ event */
 486 static llc_station_action_t llc_stat_dupaddr_state_actions_6[] = {
 487         [0] = llc_station_ac_report_status,     /* STATION DOWN */
 488         [1] = NULL,
 489 };
 490
 491 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_6 = {
 492         .ev         = llc_stat_ev_disable_req,
 493         .next_state = LLC_STATION_STATE_DOWN,
 494         .ev_actions = llc_stat_dupaddr_state_actions_6,
 495 };
 496
 497 /* array of pointers; one to each transition */
 498 static struct llc_station_state_trans *llc_stat_dupaddr_state_trans[] = {
 499         [0] = &llc_stat_dupaddr_state_trans_6,  /* Request */
 500         [1] = &llc_stat_dupaddr_state_trans_4,  /* Timer */
 501         [2] = &llc_stat_dupaddr_state_trans_5,
 502         [3] = &llc_stat_dupaddr_state_trans_1,  /* Receive frame */
 503         [4] = &llc_stat_dupaddr_state_trans_2,
 504         [5] = &llc_stat_dupaddr_state_trans_3,
 505         [6] = &llc_stat_state_trans_end,
 506 };
 507
 508 static struct llc_station_state
 509                         llc_station_state_table[LLC_NBR_STATION_STATES] = {
 510         [LLC_STATION_STATE_DOWN - 1] = {
 511                 .curr_state  = LLC_STATION_STATE_DOWN,
 512                 .transitions = llc_stat_dwn_state_trans,
 513         },
 514         [LLC_STATION_STATE_DUP_ADDR_CHK - 1] = {
 515                 .curr_state  = LLC_STATION_STATE_DUP_ADDR_CHK,
 516                 .transitions = llc_stat_dupaddr_state_trans,
 517         },
 518         [LLC_STATION_STATE_UP - 1] = {
 519                 .curr_state  = LLC_STATION_STATE_UP,
 520                 .transitions = llc_stat_up_state_trans,
 521         },
 522 };
 523
 524 /**
 525  *      llc_exec_station_trans_actions - executes actions for transition
 526  *      @trans: Address of the transition
 527  *      @skb: Address of the event that caused the transition
 528  *
 529  *      Executes actions of a transition of the station state machine. Returns
 530  *      0 if all actions complete successfully, nonzero otherwise.
 531  */
 532 static u16 llc_exec_station_trans_actions(struct llc_station_state_trans *trans,
 533                                           struct sk_buff *skb)
 534 {
 535         u16 rc = 0;
 536         llc_station_action_t *next_action = trans->ev_actions;
 537
 538         for (; next_action && *next_action; next_action++)
 539                 if ((*next_action)(skb))
 540                         rc = 1;
 541         return rc;
 542 }
 543
 544 /**
 545  *      llc_find_station_trans - finds transition for this event
 546  *      @skb: Address of the event
 547  *
 548  *      Search thru events of the current state of the station until list
 549  *      exhausted or it's obvious that the event is not valid for the current
 550  *      state. Returns the address of the transition if cound, %NULL otherwise.
 551  */
 552 static struct llc_station_state_trans *
 553                                 llc_find_station_trans(struct sk_buff *skb)
 554 {
 555         int i = 0;
 556         struct llc_station_state_trans *rc = NULL;
 557         struct llc_station_state_trans **next_trans;
 558         struct llc_station_state *curr_state =
 559                                 &llc_station_state_table[llc_main_station.state - 1];
 560
 561         for (next_trans = curr_state->transitions; next_trans[i]->ev; i++)
 562                 if (!next_trans[i]->ev(skb)) {
 563                         rc = next_trans[i];
 564                         break;
 565                 }
 566         return rc;
 567 }
 568
 569 /**
 570  *      llc_station_free_ev - frees an event
 571  *      @skb: Address of the event
 572  *
 573  *      Frees an event.
 574  */
 575 static void llc_station_free_ev(struct sk_buff *skb)
 576 {
 577         struct llc_station_state_ev *ev = llc_station_ev(skb);
 578
 579         if (ev->type == LLC_STATION_EV_TYPE_PDU)
 580                 kfree_skb(skb);
 581 }
 582
 583 /**
 584  *      llc_station_next_state - processes event and goes to the next state
 585  *      @skb: Address of the event
 586  *
 587  *      Processes an event, executes any transitions related to that event and
 588  *      updates the state of the station.
 589  */
 590 static u16 llc_station_next_state(struct sk_buff *skb)
 591 {
 592         u16 rc = 1;
 593         struct llc_station_state_trans *trans;
 594
 595         if (llc_main_station.state > LLC_NBR_STATION_STATES)
 596                 goto out;
 597         trans = llc_find_station_trans(skb);
 598         if (trans) {
 599                 /* got the state to which we next transition; perform the
 600                  * actions associated with this transition before actually
 601                  * transitioning to the next state
 602                  */
 603                 rc = llc_exec_station_trans_actions(trans, skb);
 604                 if (!rc)
 605                         /* transition station to next state if all actions
 606                          * execute successfully; done; wait for next event
 607                          */
 608                         llc_main_station.state = trans->next_state;
 609         } else
 610                 /* event not recognized in current state; re-queue it for
 611                  * processing again at a later time; return failure
 612                  */
 613                 rc = 0;
 614 out:
 615         llc_station_free_ev(skb);
 616         return rc;
 617 }
 618
 619 /**
 620  *      llc_station_service_events - service events in the queue
 621  *
 622  *      Get an event from the station event queue (if any); attempt to service
 623  *      the event; if event serviced, get the next event (if any) on the event
 624  *      queue; if event not service, re-queue the event on the event queue and
 625  *      attempt to service the next event; when serviced all events in queue,
 626  *      finished; if don't transition to different state, just service all
 627  *      events once; if transition to new state, service all events again.
 628  *      Caller must hold llc_main_station.ev_q.lock.
 629  */
 630 static void llc_station_service_events(void)
 631 {
 632         struct sk_buff *skb;
 633
 634         while ((skb = skb_dequeue(&llc_main_station.ev_q.list)) != NULL)
 635                 llc_station_next_state(skb);
 636 }
 637
 638 /**
 639  *      llc_station_state_process: queue event and try to process queue.
 640  *      @skb: Address of the event
 641  *
 642  *      Queues an event (on the station event queue) for handling by the
 643  *      station state machine and attempts to process any queued-up events.
 644  */
 645 static void llc_station_state_process(struct sk_buff *skb)
 646 {
 647         spin_lock_bh(&llc_main_station.ev_q.lock);
 648         skb_queue_tail(&llc_main_station.ev_q.list, skb);
 649         llc_station_service_events();
 650         spin_unlock_bh(&llc_main_station.ev_q.lock);
 651 }
 652
 653 static void llc_station_ack_tmr_cb(unsigned long timeout_data)
 654 {
 655         struct sk_buff *skb = alloc_skb(0, GFP_ATOMIC);
 656
 657         if (skb) {
 658                 struct llc_station_state_ev *ev = llc_station_ev(skb);
 659
 660                 ev->type = LLC_STATION_EV_TYPE_ACK_TMR;
 661                 llc_station_state_process(skb);
 662         }
 663 }
 664
 665 /*
 666  *      llc_station_rcv - send received pdu to the station state machine
 667  *      @skb: received frame.
 668  *
 669  *      Sends data unit to station state machine.
 670  */
 671 static void llc_station_rcv(struct sk_buff *skb)
 672 {
 673         struct llc_station_state_ev *ev = llc_station_ev(skb);
 674
 675         ev->type   = LLC_STATION_EV_TYPE_PDU;
 676         ev->reason = 0;
 677         llc_station_state_process(skb);
 678 }
 679
 680 int __init llc_station_init(void)
 681 {
 682         u16 rc = -ENOBUFS;
 683         struct sk_buff *skb;
 684         struct llc_station_state_ev *ev;
 685
 686         skb_queue_head_init(&llc_main_station.mac_pdu_q);
 687         skb_queue_head_init(&llc_main_station.ev_q.list);
 688         spin_lock_init(&llc_main_station.ev_q.lock);
 689         init_timer(&llc_main_station.ack_timer);
 690         llc_main_station.ack_timer.data     = (unsigned long)&llc_main_station;
 691         llc_main_station.ack_timer.function = llc_station_ack_tmr_cb;
 692
 693         skb = alloc_skb(0, GFP_ATOMIC);
 694         if (!skb)
 695                 goto out;
 696         rc = 0;
 697         llc_set_station_handler(llc_station_rcv);
 698         ev = llc_station_ev(skb);
 699         memset(ev, 0, sizeof(*ev));
 700         llc_main_station.ack_timer.expires = jiffies + 3 * HZ;
 701         llc_main_station.maximum_retry  = 1;
 702         llc_main_station.state          = LLC_STATION_STATE_DOWN;
 703         ev->type        = LLC_STATION_EV_TYPE_SIMPLE;
 704         ev->prim_type   = LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK;
 705         rc = llc_station_next_state(skb);
 706 out:
 707         return rc;
 708 }
 709
 710 void __exit llc_station_exit(void)
 711 {
 712         llc_set_station_handler(NULL);
 713 }