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   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(skb->dev);
 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(skb->dev);
 274
 275         if (!nskb)
 276                 goto out;
 277         rc = 0;
 278         llc_pdu_decode_sa(skb, mac_da);
 279         llc_pdu_decode_ssap(skb, &dsap);
 280         llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
 281         llc_pdu_init_as_xid_rsp(nskb, LLC_XID_NULL_CLASS_2, 127);
 282         rc = llc_mac_hdr_init(nskb, llc_station_mac_sa, mac_da);
 283         if (rc)
 284                 goto free;
 285         llc_station_send_pdu(nskb);
 286 out:
 287         return rc;
 288 free:
 289         kfree_skb(skb);
 290         goto out;
 291 }
 292
 293 static int llc_station_ac_send_test_r(struct sk_buff *skb)
 294 {
 295         u8 mac_da[ETH_ALEN], dsap;
 296         int rc = 1;
 297         struct sk_buff *nskb = llc_alloc_frame(skb->dev);
 298
 299         if (!nskb)
 300                 goto out;
 301         rc = 0;
 302         llc_pdu_decode_sa(skb, mac_da);
 303         llc_pdu_decode_ssap(skb, &dsap);
 304         llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
 305         llc_pdu_init_as_test_rsp(nskb, skb);
 306         rc = llc_mac_hdr_init(nskb, llc_station_mac_sa, mac_da);
 307         if (rc)
 308                 goto free;
 309         llc_station_send_pdu(nskb);
 310 out:
 311         return rc;
 312 free:
 313         kfree_skb(skb);
 314         goto out;
 315 }
 316
 317 static int llc_station_ac_report_status(struct sk_buff *skb)
 318 {
 319         return 0;
 320 }
 321
 322 /* COMMON STATION STATE transitions */
 323
 324 /* dummy last-transition indicator; common to all state transition groups
 325  * last entry for this state
 326  * all members are zeros, .bss zeroes it
 327  */
 328 static struct llc_station_state_trans llc_stat_state_trans_end;
 329
 330 /* DOWN STATE transitions */
 331
 332 /* state transition for LLC_STATION_EV_ENABLE_WITH_DUP_ADDR_CHECK event */
 333 static llc_station_action_t llc_stat_down_state_actions_1[] = {
 334         [0] = llc_station_ac_start_ack_timer,
 335         [1] = llc_station_ac_set_retry_cnt_0,
 336         [2] = llc_station_ac_set_xid_r_cnt_0,
 337         [3] = llc_station_ac_send_null_dsap_xid_c,
 338         [4] = NULL,
 339 };
 340
 341 static struct llc_station_state_trans llc_stat_down_state_trans_1 = {
 342         .ev         = llc_stat_ev_enable_with_dup_addr_check,
 343         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
 344         .ev_actions = llc_stat_down_state_actions_1,
 345 };
 346
 347 /* state transition for LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK event */
 348 static llc_station_action_t llc_stat_down_state_actions_2[] = {
 349         [0] = llc_station_ac_report_status,     /* STATION UP */
 350         [1] = NULL,
 351 };
 352
 353 static struct llc_station_state_trans llc_stat_down_state_trans_2 = {
 354         .ev         = llc_stat_ev_enable_without_dup_addr_check,
 355         .next_state = LLC_STATION_STATE_UP,
 356         .ev_actions = llc_stat_down_state_actions_2,
 357 };
 358
 359 /* array of pointers; one to each transition */
 360 static struct llc_station_state_trans *llc_stat_dwn_state_trans[] = {
 361         [0] = &llc_stat_down_state_trans_1,
 362         [1] = &llc_stat_down_state_trans_2,
 363         [2] = &llc_stat_state_trans_end,
 364 };
 365
 366 /* UP STATE transitions */
 367 /* state transition for LLC_STATION_EV_DISABLE_REQ event */
 368 static llc_station_action_t llc_stat_up_state_actions_1[] = {
 369         [0] = llc_station_ac_report_status,     /* STATION DOWN */
 370         [1] = NULL,
 371 };
 372
 373 static struct llc_station_state_trans llc_stat_up_state_trans_1 = {
 374         .ev         = llc_stat_ev_disable_req,
 375         .next_state = LLC_STATION_STATE_DOWN,
 376         .ev_actions = llc_stat_up_state_actions_1,
 377 };
 378
 379 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_XID_C event */
 380 static llc_station_action_t llc_stat_up_state_actions_2[] = {
 381         [0] = llc_station_ac_send_xid_r,
 382         [1] = NULL,
 383 };
 384
 385 static struct llc_station_state_trans llc_stat_up_state_trans_2 = {
 386         .ev         = llc_stat_ev_rx_null_dsap_xid_c,
 387         .next_state = LLC_STATION_STATE_UP,
 388         .ev_actions = llc_stat_up_state_actions_2,
 389 };
 390
 391 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_TEST_C event */
 392 static llc_station_action_t llc_stat_up_state_actions_3[] = {
 393         [0] = llc_station_ac_send_test_r,
 394         [1] = NULL,
 395 };
 396
 397 static struct llc_station_state_trans llc_stat_up_state_trans_3 = {
 398         .ev         = llc_stat_ev_rx_null_dsap_test_c,
 399         .next_state = LLC_STATION_STATE_UP,
 400         .ev_actions = llc_stat_up_state_actions_3,
 401 };
 402
 403 /* array of pointers; one to each transition */
 404 static struct llc_station_state_trans *llc_stat_up_state_trans [] = {
 405         [0] = &llc_stat_up_state_trans_1,
 406         [1] = &llc_stat_up_state_trans_2,
 407         [2] = &llc_stat_up_state_trans_3,
 408         [3] = &llc_stat_state_trans_end,
 409 };
 410
 411 /* DUP ADDR CHK STATE transitions */
 412 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_0_XID_R_XID_R_CNT_EQ
 413  * event
 414  */
 415 static llc_station_action_t llc_stat_dupaddr_state_actions_1[] = {
 416         [0] = llc_station_ac_inc_xid_r_cnt_by_1,
 417         [1] = NULL,
 418 };
 419
 420 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_1 = {
 421         .ev         = llc_stat_ev_rx_null_dsap_0_xid_r_xid_r_cnt_eq,
 422         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
 423         .ev_actions = llc_stat_dupaddr_state_actions_1,
 424 };
 425
 426 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_1_XID_R_XID_R_CNT_EQ
 427  * event
 428  */
 429 static llc_station_action_t llc_stat_dupaddr_state_actions_2[] = {
 430         [0] = llc_station_ac_report_status,     /* DUPLICATE ADDRESS FOUND */
 431         [1] = NULL,
 432 };
 433
 434 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_2 = {
 435         .ev         = llc_stat_ev_rx_null_dsap_1_xid_r_xid_r_cnt_eq,
 436         .next_state = LLC_STATION_STATE_DOWN,
 437         .ev_actions = llc_stat_dupaddr_state_actions_2,
 438 };
 439
 440 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_XID_C event */
 441 static llc_station_action_t llc_stat_dupaddr_state_actions_3[] = {
 442         [0] = llc_station_ac_send_xid_r,
 443         [1] = NULL,
 444 };
 445
 446 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_3 = {
 447         .ev         = llc_stat_ev_rx_null_dsap_xid_c,
 448         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
 449         .ev_actions = llc_stat_dupaddr_state_actions_3,
 450 };
 451
 452 /* state transition for LLC_STATION_EV_ACK_TMR_EXP_LT_RETRY_CNT_MAX_RETRY
 453  * event
 454  */
 455 static llc_station_action_t llc_stat_dupaddr_state_actions_4[] = {
 456         [0] = llc_station_ac_start_ack_timer,
 457         [1] = llc_station_ac_inc_retry_cnt_by_1,
 458         [2] = llc_station_ac_set_xid_r_cnt_0,
 459         [3] = llc_station_ac_send_null_dsap_xid_c,
 460         [4] = NULL,
 461 };
 462
 463 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_4 = {
 464         .ev         = llc_stat_ev_ack_tmr_exp_lt_retry_cnt_max_retry,
 465         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
 466         .ev_actions = llc_stat_dupaddr_state_actions_4,
 467 };
 468
 469 /* state transition for LLC_STATION_EV_ACK_TMR_EXP_EQ_RETRY_CNT_MAX_RETRY
 470  * event
 471  */
 472 static llc_station_action_t llc_stat_dupaddr_state_actions_5[] = {
 473         [0] = llc_station_ac_report_status,     /* STATION UP */
 474         [1] = NULL,
 475 };
 476
 477 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_5 = {
 478         .ev         = llc_stat_ev_ack_tmr_exp_eq_retry_cnt_max_retry,
 479         .next_state = LLC_STATION_STATE_UP,
 480         .ev_actions = llc_stat_dupaddr_state_actions_5,
 481 };
 482
 483 /* state transition for LLC_STATION_EV_DISABLE_REQ event */
 484 static llc_station_action_t llc_stat_dupaddr_state_actions_6[] = {
 485         [0] = llc_station_ac_report_status,     /* STATION DOWN */
 486         [1] = NULL,
 487 };
 488
 489 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_6 = {
 490         .ev         = llc_stat_ev_disable_req,
 491         .next_state = LLC_STATION_STATE_DOWN,
 492         .ev_actions = llc_stat_dupaddr_state_actions_6,
 493 };
 494
 495 /* array of pointers; one to each transition */
 496 static struct llc_station_state_trans *llc_stat_dupaddr_state_trans[] = {
 497         [0] = &llc_stat_dupaddr_state_trans_6,  /* Request */
 498         [1] = &llc_stat_dupaddr_state_trans_4,  /* Timer */
 499         [2] = &llc_stat_dupaddr_state_trans_5,
 500         [3] = &llc_stat_dupaddr_state_trans_1,  /* Receive frame */
 501         [4] = &llc_stat_dupaddr_state_trans_2,
 502         [5] = &llc_stat_dupaddr_state_trans_3,
 503         [6] = &llc_stat_state_trans_end,
 504 };
 505
 506 static struct llc_station_state
 507                         llc_station_state_table[LLC_NBR_STATION_STATES] = {
 508         [LLC_STATION_STATE_DOWN - 1] = {
 509                 .curr_state  = LLC_STATION_STATE_DOWN,
 510                 .transitions = llc_stat_dwn_state_trans,
 511         },
 512         [LLC_STATION_STATE_DUP_ADDR_CHK - 1] = {
 513                 .curr_state  = LLC_STATION_STATE_DUP_ADDR_CHK,
 514                 .transitions = llc_stat_dupaddr_state_trans,
 515         },
 516         [LLC_STATION_STATE_UP - 1] = {
 517                 .curr_state  = LLC_STATION_STATE_UP,
 518                 .transitions = llc_stat_up_state_trans,
 519         },
 520 };
 521
 522 /**
 523  *      llc_exec_station_trans_actions - executes actions for transition
 524  *      @trans: Address of the transition
 525  *      @skb: Address of the event that caused the transition
 526  *
 527  *      Executes actions of a transition of the station state machine. Returns
 528  *      0 if all actions complete successfully, nonzero otherwise.
 529  */
 530 static u16 llc_exec_station_trans_actions(struct llc_station_state_trans *trans,
 531                                           struct sk_buff *skb)
 532 {
 533         u16 rc = 0;
 534         llc_station_action_t *next_action = trans->ev_actions;
 535
 536         for (; next_action && *next_action; next_action++)
 537                 if ((*next_action)(skb))
 538                         rc = 1;
 539         return rc;
 540 }
 541
 542 /**
 543  *      llc_find_station_trans - finds transition for this event
 544  *      @skb: Address of the event
 545  *
 546  *      Search thru events of the current state of the station until list
 547  *      exhausted or it's obvious that the event is not valid for the current
 548  *      state. Returns the address of the transition if cound, %NULL otherwise.
 549  */
 550 static struct llc_station_state_trans *
 551                                 llc_find_station_trans(struct sk_buff *skb)
 552 {
 553         int i = 0;
 554         struct llc_station_state_trans *rc = NULL;
 555         struct llc_station_state_trans **next_trans;
 556         struct llc_station_state *curr_state =
 557                                 &llc_station_state_table[llc_main_station.state - 1];
 558
 559         for (next_trans = curr_state->transitions; next_trans[i]->ev; i++)
 560                 if (!next_trans[i]->ev(skb)) {
 561                         rc = next_trans[i];
 562                         break;
 563                 }
 564         return rc;
 565 }
 566
 567 /**
 568  *      llc_station_free_ev - frees an event
 569  *      @skb: Address of the event
 570  *
 571  *      Frees an event.
 572  */
 573 static void llc_station_free_ev(struct sk_buff *skb)
 574 {
 575         struct llc_station_state_ev *ev = llc_station_ev(skb);
 576
 577         if (ev->type == LLC_STATION_EV_TYPE_PDU)
 578                 kfree_skb(skb);
 579 }
 580
 581 /**
 582  *      llc_station_next_state - processes event and goes to the next state
 583  *      @skb: Address of the event
 584  *
 585  *      Processes an event, executes any transitions related to that event and
 586  *      updates the state of the station.
 587  */
 588 static u16 llc_station_next_state(struct sk_buff *skb)
 589 {
 590         u16 rc = 1;
 591         struct llc_station_state_trans *trans;
 592
 593         if (llc_main_station.state > LLC_NBR_STATION_STATES)
 594                 goto out;
 595         trans = llc_find_station_trans(skb);
 596         if (trans) {
 597                 /* got the state to which we next transition; perform the
 598                  * actions associated with this transition before actually
 599                  * transitioning to the next state
 600                  */
 601                 rc = llc_exec_station_trans_actions(trans, skb);
 602                 if (!rc)
 603                         /* transition station to next state if all actions
 604                          * execute successfully; done; wait for next event
 605                          */
 606                         llc_main_station.state = trans->next_state;
 607         } else
 608                 /* event not recognized in current state; re-queue it for
 609                  * processing again at a later time; return failure
 610                  */
 611                 rc = 0;
 612 out:
 613         llc_station_free_ev(skb);
 614         return rc;
 615 }
 616
 617 /**
 618  *      llc_station_service_events - service events in the queue
 619  *
 620  *      Get an event from the station event queue (if any); attempt to service
 621  *      the event; if event serviced, get the next event (if any) on the event
 622  *      queue; if event not service, re-queue the event on the event queue and
 623  *      attempt to service the next event; when serviced all events in queue,
 624  *      finished; if don't transition to different state, just service all
 625  *      events once; if transition to new state, service all events again.
 626  *      Caller must hold llc_main_station.ev_q.lock.
 627  */
 628 static void llc_station_service_events(void)
 629 {
 630         struct sk_buff *skb;
 631
 632         while ((skb = skb_dequeue(&llc_main_station.ev_q.list)) != NULL)
 633                 llc_station_next_state(skb);
 634 }
 635
 636 /**
 637  *      llc_station_state_process: queue event and try to process queue.
 638  *      @skb: Address of the event
 639  *
 640  *      Queues an event (on the station event queue) for handling by the
 641  *      station state machine and attempts to process any queued-up events.
 642  */
 643 static void llc_station_state_process(struct sk_buff *skb)
 644 {
 645         spin_lock_bh(&llc_main_station.ev_q.lock);
 646         skb_queue_tail(&llc_main_station.ev_q.list, skb);
 647         llc_station_service_events();
 648         spin_unlock_bh(&llc_main_station.ev_q.lock);
 649 }
 650
 651 static void llc_station_ack_tmr_cb(unsigned long timeout_data)
 652 {
 653         struct sk_buff *skb = alloc_skb(0, GFP_ATOMIC);
 654
 655         if (skb) {
 656                 struct llc_station_state_ev *ev = llc_station_ev(skb);
 657
 658                 ev->type = LLC_STATION_EV_TYPE_ACK_TMR;
 659                 llc_station_state_process(skb);
 660         }
 661 }
 662
 663 /*
 664  *      llc_station_rcv - send received pdu to the station state machine
 665  *      @skb: received frame.
 666  *
 667  *      Sends data unit to station state machine.
 668  */
 669 static void llc_station_rcv(struct sk_buff *skb)
 670 {
 671         struct llc_station_state_ev *ev = llc_station_ev(skb);
 672
 673         ev->type   = LLC_STATION_EV_TYPE_PDU;
 674         ev->reason = 0;
 675         llc_station_state_process(skb);
 676 }
 677
 678 int __init llc_station_init(void)
 679 {
 680         u16 rc = -ENOBUFS;
 681         struct sk_buff *skb;
 682         struct llc_station_state_ev *ev;
 683
 684         skb_queue_head_init(&llc_main_station.mac_pdu_q);
 685         skb_queue_head_init(&llc_main_station.ev_q.list);
 686         spin_lock_init(&llc_main_station.ev_q.lock);
 687         init_timer(&llc_main_station.ack_timer);
 688         llc_main_station.ack_timer.data     = (unsigned long)&llc_main_station;
 689         llc_main_station.ack_timer.function = llc_station_ack_tmr_cb;
 690
 691         skb = alloc_skb(0, GFP_ATOMIC);
 692         if (!skb)
 693                 goto out;
 694         rc = 0;
 695         llc_set_station_handler(llc_station_rcv);
 696         ev = llc_station_ev(skb);
 697         memset(ev, 0, sizeof(*ev));
 698         llc_main_station.ack_timer.expires = jiffies + 3 * HZ;
 699         llc_main_station.maximum_retry  = 1;
 700         llc_main_station.state          = LLC_STATION_STATE_DOWN;
 701         ev->type        = LLC_STATION_EV_TYPE_SIMPLE;
 702         ev->prim_type   = LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK;
 703         rc = llc_station_next_state(skb);
 704 out:
 705         return rc;
 706 }
 707
 708 void __exit llc_station_exit(void)
 709 {
 710         llc_set_station_handler(NULL);
 711 }