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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/init.h>
  15 #include <linux/module.h>
  16 #include <net/llc.h>
  17 #include <net/llc_sap.h>
  18 #include <net/llc_conn.h>
  19 #include <net/llc_c_ac.h>
  20 #include <net/llc_s_ac.h>
  21 #include <net/llc_c_ev.h>
  22 #include <net/llc_c_st.h>
  23 #include <net/llc_s_ev.h>
  24 #include <net/llc_s_st.h>
  25 #include <net/llc_pdu.h>
  26
  27 /**
  28  * struct llc_station - LLC station component
  29  *
  30  * SAP and connection resource manager, one per adapter.
  31  *
  32  * @state - state of station
  33  * @xid_r_count - XID response PDU counter
  34  * @mac_sa - MAC source address
  35  * @sap_list - list of related SAPs
  36  * @ev_q - events entering state mach.
  37  * @mac_pdu_q - PDUs ready to send to MAC
  38  */
  39 struct llc_station {
  40         u8                          state;
  41         u8                          xid_r_count;
  42         struct timer_list           ack_timer;
  43         u8                          retry_count;
  44         u8                          maximum_retry;
  45         struct {
  46                 struct sk_buff_head list;
  47                 spinlock_t          lock;
  48         } ev_q;
  49         struct sk_buff_head         mac_pdu_q;
  50 };
  51
  52 #define LLC_STATION_ACK_TIME (3 * HZ)
  53
  54 int sysctl_llc_station_ack_timeout = LLC_STATION_ACK_TIME;
  55
  56 /* Types of events (possible values in 'ev->type') */
  57 #define LLC_STATION_EV_TYPE_SIMPLE      1
  58 #define LLC_STATION_EV_TYPE_CONDITION   2
  59 #define LLC_STATION_EV_TYPE_PRIM        3
  60 #define LLC_STATION_EV_TYPE_PDU         4       /* command/response PDU */
  61 #define LLC_STATION_EV_TYPE_ACK_TMR     5
  62 #define LLC_STATION_EV_TYPE_RPT_STATUS  6
  63
  64 /* Events */
  65 #define LLC_STATION_EV_ENABLE_WITH_DUP_ADDR_CHECK               1
  66 #define LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK            2
  67 #define LLC_STATION_EV_ACK_TMR_EXP_LT_RETRY_CNT_MAX_RETRY       3
  68 #define LLC_STATION_EV_ACK_TMR_EXP_EQ_RETRY_CNT_MAX_RETRY       4
  69 #define LLC_STATION_EV_RX_NULL_DSAP_XID_C                       5
  70 #define LLC_STATION_EV_RX_NULL_DSAP_0_XID_R_XID_R_CNT_EQ        6
  71 #define LLC_STATION_EV_RX_NULL_DSAP_1_XID_R_XID_R_CNT_EQ        7
  72 #define LLC_STATION_EV_RX_NULL_DSAP_TEST_C                      8
  73 #define LLC_STATION_EV_DISABLE_REQ                              9
  74
  75 struct llc_station_state_ev {
  76         u8               type;
  77         u8               prim;
  78         u8               prim_type;
  79         u8               reason;
  80         struct list_head node; /* node in station->ev_q.list */
  81 };
  82
  83 static __inline__ struct llc_station_state_ev *
  84                                         llc_station_ev(struct sk_buff *skb)
  85 {
  86         return (struct llc_station_state_ev *)skb->cb;
  87 }
  88
  89 typedef int (*llc_station_ev_t)(struct sk_buff *skb);
  90
  91 #define LLC_STATION_STATE_DOWN          1       /* initial state */
  92 #define LLC_STATION_STATE_DUP_ADDR_CHK  2
  93 #define LLC_STATION_STATE_UP            3
  94
  95 #define LLC_NBR_STATION_STATES          3       /* size of state table */
  96
  97 typedef int (*llc_station_action_t)(struct sk_buff *skb);
  98
  99 /* Station component state table structure */
 100 struct llc_station_state_trans {
 101         llc_station_ev_t ev;
 102         u8 next_state;
 103         llc_station_action_t *ev_actions;
 104 };
 105
 106 struct llc_station_state {
 107         u8 curr_state;
 108         struct llc_station_state_trans **transitions;
 109 };
 110
 111 static struct llc_station llc_main_station;
 112
 113 static int llc_stat_ev_enable_with_dup_addr_check(struct sk_buff *skb)
 114 {
 115         struct llc_station_state_ev *ev = llc_station_ev(skb);
 116
 117         return ev->type == LLC_STATION_EV_TYPE_SIMPLE &&
 118                ev->prim_type ==
 119                               LLC_STATION_EV_ENABLE_WITH_DUP_ADDR_CHECK ? 0 : 1;
 120 }
 121
 122 static int llc_stat_ev_enable_without_dup_addr_check(struct sk_buff *skb)
 123 {
 124         struct llc_station_state_ev *ev = llc_station_ev(skb);
 125
 126         return ev->type == LLC_STATION_EV_TYPE_SIMPLE &&
 127                ev->prim_type ==
 128                         LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK ? 0 : 1;
 129 }
 130
 131 static int llc_stat_ev_ack_tmr_exp_lt_retry_cnt_max_retry(struct sk_buff *skb)
 132 {
 133         struct llc_station_state_ev *ev = llc_station_ev(skb);
 134
 135         return ev->type == LLC_STATION_EV_TYPE_ACK_TMR &&
 136                 llc_main_station.retry_count <
 137                 llc_main_station.maximum_retry ? 0 : 1;
 138 }
 139
 140 static int llc_stat_ev_ack_tmr_exp_eq_retry_cnt_max_retry(struct sk_buff *skb)
 141 {
 142         struct llc_station_state_ev *ev = llc_station_ev(skb);
 143
 144         return ev->type == LLC_STATION_EV_TYPE_ACK_TMR &&
 145                 llc_main_station.retry_count ==
 146                 llc_main_station.maximum_retry ? 0 : 1;
 147 }
 148
 149 static int llc_stat_ev_rx_null_dsap_xid_c(struct sk_buff *skb)
 150 {
 151         struct llc_station_state_ev *ev = llc_station_ev(skb);
 152         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
 153
 154         return ev->type == LLC_STATION_EV_TYPE_PDU &&
 155                LLC_PDU_IS_CMD(pdu) &&                   /* command PDU */
 156                LLC_PDU_TYPE_IS_U(pdu) &&                /* U type PDU */
 157                LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_XID &&
 158                !pdu->dsap ? 0 : 1;                      /* NULL DSAP value */
 159 }
 160
 161 static int llc_stat_ev_rx_null_dsap_0_xid_r_xid_r_cnt_eq(struct sk_buff *skb)
 162 {
 163         struct llc_station_state_ev *ev = llc_station_ev(skb);
 164         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
 165
 166         return ev->type == LLC_STATION_EV_TYPE_PDU &&
 167                LLC_PDU_IS_RSP(pdu) &&                   /* response PDU */
 168                LLC_PDU_TYPE_IS_U(pdu) &&                /* U type PDU */
 169                LLC_U_PDU_RSP(pdu) == LLC_1_PDU_CMD_XID &&
 170                !pdu->dsap &&                            /* NULL DSAP value */
 171                !llc_main_station.xid_r_count ? 0 : 1;
 172 }
 173
 174 static int llc_stat_ev_rx_null_dsap_1_xid_r_xid_r_cnt_eq(struct sk_buff *skb)
 175 {
 176         struct llc_station_state_ev *ev = llc_station_ev(skb);
 177         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
 178
 179         return ev->type == LLC_STATION_EV_TYPE_PDU &&
 180                LLC_PDU_IS_RSP(pdu) &&                   /* response PDU */
 181                LLC_PDU_TYPE_IS_U(pdu) &&                /* U type PDU */
 182                LLC_U_PDU_RSP(pdu) == LLC_1_PDU_CMD_XID &&
 183                !pdu->dsap &&                            /* NULL DSAP value */
 184                llc_main_station.xid_r_count == 1 ? 0 : 1;
 185 }
 186
 187 static int llc_stat_ev_rx_null_dsap_test_c(struct sk_buff *skb)
 188 {
 189         struct llc_station_state_ev *ev = llc_station_ev(skb);
 190         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
 191
 192         return ev->type == LLC_STATION_EV_TYPE_PDU &&
 193                LLC_PDU_IS_CMD(pdu) &&                   /* command PDU */
 194                LLC_PDU_TYPE_IS_U(pdu) &&                /* U type PDU */
 195                LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_TEST &&
 196                !pdu->dsap ? 0 : 1;                      /* NULL DSAP */
 197 }
 198
 199 static int llc_stat_ev_disable_req(struct sk_buff *skb)
 200 {
 201         struct llc_station_state_ev *ev = llc_station_ev(skb);
 202
 203         return ev->type == LLC_STATION_EV_TYPE_PRIM &&
 204                ev->prim == LLC_DISABLE_PRIM &&
 205                ev->prim_type == LLC_PRIM_TYPE_REQ ? 0 : 1;
 206 }
 207
 208 /**
 209  *      llc_station_send_pdu - queues PDU to send
 210  *      @skb: Address of the PDU
 211  *
 212  *      Queues a PDU to send to the MAC layer.
 213  */
 214 static void llc_station_send_pdu(struct sk_buff *skb)
 215 {
 216         skb_queue_tail(&llc_main_station.mac_pdu_q, skb);
 217         while ((skb = skb_dequeue(&llc_main_station.mac_pdu_q)) != NULL)
 218                 if (dev_queue_xmit(skb))
 219                         break;
 220 }
 221
 222 static int llc_station_ac_start_ack_timer(struct sk_buff *skb)
 223 {
 224         mod_timer(&llc_main_station.ack_timer,
 225                   jiffies + sysctl_llc_station_ack_timeout);
 226         return 0;
 227 }
 228
 229 static int llc_station_ac_set_retry_cnt_0(struct sk_buff *skb)
 230 {
 231         llc_main_station.retry_count = 0;
 232         return 0;
 233 }
 234
 235 static int llc_station_ac_inc_retry_cnt_by_1(struct sk_buff *skb)
 236 {
 237         llc_main_station.retry_count++;
 238         return 0;
 239 }
 240
 241 static int llc_station_ac_set_xid_r_cnt_0(struct sk_buff *skb)
 242 {
 243         llc_main_station.xid_r_count = 0;
 244         return 0;
 245 }
 246
 247 static int llc_station_ac_inc_xid_r_cnt_by_1(struct sk_buff *skb)
 248 {
 249         llc_main_station.xid_r_count++;
 250         return 0;
 251 }
 252
 253 static int llc_station_ac_send_null_dsap_xid_c(struct sk_buff *skb)
 254 {
 255         int rc = 1;
 256         struct sk_buff *nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U,
 257                                                sizeof(struct llc_xid_info));
 258
 259         if (!nskb)
 260                 goto out;
 261         llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, 0, LLC_PDU_CMD);
 262         llc_pdu_init_as_xid_cmd(nskb, LLC_XID_NULL_CLASS_2, 127);
 263         rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, skb->dev->dev_addr);
 264         if (unlikely(rc))
 265                 goto free;
 266         llc_station_send_pdu(nskb);
 267 out:
 268         return rc;
 269 free:
 270         kfree_skb(skb);
 271         goto out;
 272 }
 273
 274 static int llc_station_ac_send_xid_r(struct sk_buff *skb)
 275 {
 276         u8 mac_da[ETH_ALEN], dsap;
 277         int rc = 1;
 278         struct sk_buff *nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U,
 279                                                sizeof(struct llc_xid_info));
 280
 281         if (!nskb)
 282                 goto out;
 283         rc = 0;
 284         llc_pdu_decode_sa(skb, mac_da);
 285         llc_pdu_decode_ssap(skb, &dsap);
 286         llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
 287         llc_pdu_init_as_xid_rsp(nskb, LLC_XID_NULL_CLASS_2, 127);
 288         rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);
 289         if (unlikely(rc))
 290                 goto free;
 291         llc_station_send_pdu(nskb);
 292 out:
 293         return rc;
 294 free:
 295         kfree_skb(skb);
 296         goto out;
 297 }
 298
 299 static int llc_station_ac_send_test_r(struct sk_buff *skb)
 300 {
 301         u8 mac_da[ETH_ALEN], dsap;
 302         int rc = 1;
 303         u32 data_size;
 304         struct sk_buff *nskb;
 305
 306         /* The test request command is type U (llc_len = 3) */
 307         data_size = ntohs(eth_hdr(skb)->h_proto) - 3;
 308         nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U, data_size);
 309
 310         if (!nskb)
 311                 goto out;
 312         rc = 0;
 313         llc_pdu_decode_sa(skb, mac_da);
 314         llc_pdu_decode_ssap(skb, &dsap);
 315         llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
 316         llc_pdu_init_as_test_rsp(nskb, skb);
 317         rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);
 318         if (unlikely(rc))
 319                 goto free;
 320         llc_station_send_pdu(nskb);
 321 out:
 322         return rc;
 323 free:
 324         kfree_skb(skb);
 325         goto out;
 326 }
 327
 328 static int llc_station_ac_report_status(struct sk_buff *skb)
 329 {
 330         return 0;
 331 }
 332
 333 /* COMMON STATION STATE transitions */
 334
 335 /* dummy last-transition indicator; common to all state transition groups
 336  * last entry for this state
 337  * all members are zeros, .bss zeroes it
 338  */
 339 static struct llc_station_state_trans llc_stat_state_trans_end;
 340
 341 /* DOWN STATE transitions */
 342
 343 /* state transition for LLC_STATION_EV_ENABLE_WITH_DUP_ADDR_CHECK event */
 344 static llc_station_action_t llc_stat_down_state_actions_1[] = {
 345         [0] = llc_station_ac_start_ack_timer,
 346         [1] = llc_station_ac_set_retry_cnt_0,
 347         [2] = llc_station_ac_set_xid_r_cnt_0,
 348         [3] = llc_station_ac_send_null_dsap_xid_c,
 349         [4] = NULL,
 350 };
 351
 352 static struct llc_station_state_trans llc_stat_down_state_trans_1 = {
 353         .ev         = llc_stat_ev_enable_with_dup_addr_check,
 354         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
 355         .ev_actions = llc_stat_down_state_actions_1,
 356 };
 357
 358 /* state transition for LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK event */
 359 static llc_station_action_t llc_stat_down_state_actions_2[] = {
 360         [0] = llc_station_ac_report_status,     /* STATION UP */
 361         [1] = NULL,
 362 };
 363
 364 static struct llc_station_state_trans llc_stat_down_state_trans_2 = {
 365         .ev         = llc_stat_ev_enable_without_dup_addr_check,
 366         .next_state = LLC_STATION_STATE_UP,
 367         .ev_actions = llc_stat_down_state_actions_2,
 368 };
 369
 370 /* array of pointers; one to each transition */
 371 static struct llc_station_state_trans *llc_stat_dwn_state_trans[] = {
 372         [0] = &llc_stat_down_state_trans_1,
 373         [1] = &llc_stat_down_state_trans_2,
 374         [2] = &llc_stat_state_trans_end,
 375 };
 376
 377 /* UP STATE transitions */
 378 /* state transition for LLC_STATION_EV_DISABLE_REQ event */
 379 static llc_station_action_t llc_stat_up_state_actions_1[] = {
 380         [0] = llc_station_ac_report_status,     /* STATION DOWN */
 381         [1] = NULL,
 382 };
 383
 384 static struct llc_station_state_trans llc_stat_up_state_trans_1 = {
 385         .ev         = llc_stat_ev_disable_req,
 386         .next_state = LLC_STATION_STATE_DOWN,
 387         .ev_actions = llc_stat_up_state_actions_1,
 388 };
 389
 390 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_XID_C event */
 391 static llc_station_action_t llc_stat_up_state_actions_2[] = {
 392         [0] = llc_station_ac_send_xid_r,
 393         [1] = NULL,
 394 };
 395
 396 static struct llc_station_state_trans llc_stat_up_state_trans_2 = {
 397         .ev         = llc_stat_ev_rx_null_dsap_xid_c,
 398         .next_state = LLC_STATION_STATE_UP,
 399         .ev_actions = llc_stat_up_state_actions_2,
 400 };
 401
 402 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_TEST_C event */
 403 static llc_station_action_t llc_stat_up_state_actions_3[] = {
 404         [0] = llc_station_ac_send_test_r,
 405         [1] = NULL,
 406 };
 407
 408 static struct llc_station_state_trans llc_stat_up_state_trans_3 = {
 409         .ev         = llc_stat_ev_rx_null_dsap_test_c,
 410         .next_state = LLC_STATION_STATE_UP,
 411         .ev_actions = llc_stat_up_state_actions_3,
 412 };
 413
 414 /* array of pointers; one to each transition */
 415 static struct llc_station_state_trans *llc_stat_up_state_trans [] = {
 416         [0] = &llc_stat_up_state_trans_1,
 417         [1] = &llc_stat_up_state_trans_2,
 418         [2] = &llc_stat_up_state_trans_3,
 419         [3] = &llc_stat_state_trans_end,
 420 };
 421
 422 /* DUP ADDR CHK STATE transitions */
 423 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_0_XID_R_XID_R_CNT_EQ
 424  * event
 425  */
 426 static llc_station_action_t llc_stat_dupaddr_state_actions_1[] = {
 427         [0] = llc_station_ac_inc_xid_r_cnt_by_1,
 428         [1] = NULL,
 429 };
 430
 431 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_1 = {
 432         .ev         = llc_stat_ev_rx_null_dsap_0_xid_r_xid_r_cnt_eq,
 433         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
 434         .ev_actions = llc_stat_dupaddr_state_actions_1,
 435 };
 436
 437 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_1_XID_R_XID_R_CNT_EQ
 438  * event
 439  */
 440 static llc_station_action_t llc_stat_dupaddr_state_actions_2[] = {
 441         [0] = llc_station_ac_report_status,     /* DUPLICATE ADDRESS FOUND */
 442         [1] = NULL,
 443 };
 444
 445 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_2 = {
 446         .ev         = llc_stat_ev_rx_null_dsap_1_xid_r_xid_r_cnt_eq,
 447         .next_state = LLC_STATION_STATE_DOWN,
 448         .ev_actions = llc_stat_dupaddr_state_actions_2,
 449 };
 450
 451 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_XID_C event */
 452 static llc_station_action_t llc_stat_dupaddr_state_actions_3[] = {
 453         [0] = llc_station_ac_send_xid_r,
 454         [1] = NULL,
 455 };
 456
 457 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_3 = {
 458         .ev         = llc_stat_ev_rx_null_dsap_xid_c,
 459         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
 460         .ev_actions = llc_stat_dupaddr_state_actions_3,
 461 };
 462
 463 /* state transition for LLC_STATION_EV_ACK_TMR_EXP_LT_RETRY_CNT_MAX_RETRY
 464  * event
 465  */
 466 static llc_station_action_t llc_stat_dupaddr_state_actions_4[] = {
 467         [0] = llc_station_ac_start_ack_timer,
 468         [1] = llc_station_ac_inc_retry_cnt_by_1,
 469         [2] = llc_station_ac_set_xid_r_cnt_0,
 470         [3] = llc_station_ac_send_null_dsap_xid_c,
 471         [4] = NULL,
 472 };
 473
 474 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_4 = {
 475         .ev         = llc_stat_ev_ack_tmr_exp_lt_retry_cnt_max_retry,
 476         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
 477         .ev_actions = llc_stat_dupaddr_state_actions_4,
 478 };
 479
 480 /* state transition for LLC_STATION_EV_ACK_TMR_EXP_EQ_RETRY_CNT_MAX_RETRY
 481  * event
 482  */
 483 static llc_station_action_t llc_stat_dupaddr_state_actions_5[] = {
 484         [0] = llc_station_ac_report_status,     /* STATION UP */
 485         [1] = NULL,
 486 };
 487
 488 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_5 = {
 489         .ev         = llc_stat_ev_ack_tmr_exp_eq_retry_cnt_max_retry,
 490         .next_state = LLC_STATION_STATE_UP,
 491         .ev_actions = llc_stat_dupaddr_state_actions_5,
 492 };
 493
 494 /* state transition for LLC_STATION_EV_DISABLE_REQ event */
 495 static llc_station_action_t llc_stat_dupaddr_state_actions_6[] = {
 496         [0] = llc_station_ac_report_status,     /* STATION DOWN */
 497         [1] = NULL,
 498 };
 499
 500 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_6 = {
 501         .ev         = llc_stat_ev_disable_req,
 502         .next_state = LLC_STATION_STATE_DOWN,
 503         .ev_actions = llc_stat_dupaddr_state_actions_6,
 504 };
 505
 506 /* array of pointers; one to each transition */
 507 static struct llc_station_state_trans *llc_stat_dupaddr_state_trans[] = {
 508         [0] = &llc_stat_dupaddr_state_trans_6,  /* Request */
 509         [1] = &llc_stat_dupaddr_state_trans_4,  /* Timer */
 510         [2] = &llc_stat_dupaddr_state_trans_5,
 511         [3] = &llc_stat_dupaddr_state_trans_1,  /* Receive frame */
 512         [4] = &llc_stat_dupaddr_state_trans_2,
 513         [5] = &llc_stat_dupaddr_state_trans_3,
 514         [6] = &llc_stat_state_trans_end,
 515 };
 516
 517 static struct llc_station_state
 518                         llc_station_state_table[LLC_NBR_STATION_STATES] = {
 519         [LLC_STATION_STATE_DOWN - 1] = {
 520                 .curr_state  = LLC_STATION_STATE_DOWN,
 521                 .transitions = llc_stat_dwn_state_trans,
 522         },
 523         [LLC_STATION_STATE_DUP_ADDR_CHK - 1] = {
 524                 .curr_state  = LLC_STATION_STATE_DUP_ADDR_CHK,
 525                 .transitions = llc_stat_dupaddr_state_trans,
 526         },
 527         [LLC_STATION_STATE_UP - 1] = {
 528                 .curr_state  = LLC_STATION_STATE_UP,
 529                 .transitions = llc_stat_up_state_trans,
 530         },
 531 };
 532
 533 /**
 534  *      llc_exec_station_trans_actions - executes actions for transition
 535  *      @trans: Address of the transition
 536  *      @skb: Address of the event that caused the transition
 537  *
 538  *      Executes actions of a transition of the station state machine. Returns
 539  *      0 if all actions complete successfully, nonzero otherwise.
 540  */
 541 static u16 llc_exec_station_trans_actions(struct llc_station_state_trans *trans,
 542                                           struct sk_buff *skb)
 543 {
 544         u16 rc = 0;
 545         llc_station_action_t *next_action = trans->ev_actions;
 546
 547         for (; next_action && *next_action; next_action++)
 548                 if ((*next_action)(skb))
 549                         rc = 1;
 550         return rc;
 551 }
 552
 553 /**
 554  *      llc_find_station_trans - finds transition for this event
 555  *      @skb: Address of the event
 556  *
 557  *      Search thru events of the current state of the station until list
 558  *      exhausted or it's obvious that the event is not valid for the current
 559  *      state. Returns the address of the transition if cound, %NULL otherwise.
 560  */
 561 static struct llc_station_state_trans *
 562                                 llc_find_station_trans(struct sk_buff *skb)
 563 {
 564         int i = 0;
 565         struct llc_station_state_trans *rc = NULL;
 566         struct llc_station_state_trans **next_trans;
 567         struct llc_station_state *curr_state =
 568                                 &llc_station_state_table[llc_main_station.state - 1];
 569
 570         for (next_trans = curr_state->transitions; next_trans[i]->ev; i++)
 571                 if (!next_trans[i]->ev(skb)) {
 572                         rc = next_trans[i];
 573                         break;
 574                 }
 575         return rc;
 576 }
 577
 578 /**
 579  *      llc_station_free_ev - frees an event
 580  *      @skb: Address of the event
 581  *
 582  *      Frees an event.
 583  */
 584 static void llc_station_free_ev(struct sk_buff *skb)
 585 {
 586         struct llc_station_state_ev *ev = llc_station_ev(skb);
 587
 588         if (ev->type == LLC_STATION_EV_TYPE_PDU)
 589                 kfree_skb(skb);
 590 }
 591
 592 /**
 593  *      llc_station_next_state - processes event and goes to the next state
 594  *      @skb: Address of the event
 595  *
 596  *      Processes an event, executes any transitions related to that event and
 597  *      updates the state of the station.
 598  */
 599 static u16 llc_station_next_state(struct sk_buff *skb)
 600 {
 601         u16 rc = 1;
 602         struct llc_station_state_trans *trans;
 603
 604         if (llc_main_station.state > LLC_NBR_STATION_STATES)
 605                 goto out;
 606         trans = llc_find_station_trans(skb);
 607         if (trans) {
 608                 /* got the state to which we next transition; perform the
 609                  * actions associated with this transition before actually
 610                  * transitioning to the next state
 611                  */
 612                 rc = llc_exec_station_trans_actions(trans, skb);
 613                 if (!rc)
 614                         /* transition station to next state if all actions
 615                          * execute successfully; done; wait for next event
 616                          */
 617                         llc_main_station.state = trans->next_state;
 618         } else
 619                 /* event not recognized in current state; re-queue it for
 620                  * processing again at a later time; return failure
 621                  */
 622                 rc = 0;
 623 out:
 624         llc_station_free_ev(skb);
 625         return rc;
 626 }
 627
 628 /**
 629  *      llc_station_service_events - service events in the queue
 630  *
 631  *      Get an event from the station event queue (if any); attempt to service
 632  *      the event; if event serviced, get the next event (if any) on the event
 633  *      queue; if event not service, re-queue the event on the event queue and
 634  *      attempt to service the next event; when serviced all events in queue,
 635  *      finished; if don't transition to different state, just service all
 636  *      events once; if transition to new state, service all events again.
 637  *      Caller must hold llc_main_station.ev_q.lock.
 638  */
 639 static void llc_station_service_events(void)
 640 {
 641         struct sk_buff *skb;
 642
 643         while ((skb = skb_dequeue(&llc_main_station.ev_q.list)) != NULL)
 644                 llc_station_next_state(skb);
 645 }
 646
 647 /**
 648  *      llc_station_state_process: queue event and try to process queue.
 649  *      @skb: Address of the event
 650  *
 651  *      Queues an event (on the station event queue) for handling by the
 652  *      station state machine and attempts to process any queued-up events.
 653  */
 654 static void llc_station_state_process(struct sk_buff *skb)
 655 {
 656         spin_lock_bh(&llc_main_station.ev_q.lock);
 657         skb_queue_tail(&llc_main_station.ev_q.list, skb);
 658         llc_station_service_events();
 659         spin_unlock_bh(&llc_main_station.ev_q.lock);
 660 }
 661
 662 static void llc_station_ack_tmr_cb(unsigned long timeout_data)
 663 {
 664         struct sk_buff *skb = alloc_skb(0, GFP_ATOMIC);
 665
 666         if (skb) {
 667                 struct llc_station_state_ev *ev = llc_station_ev(skb);
 668
 669                 ev->type = LLC_STATION_EV_TYPE_ACK_TMR;
 670                 llc_station_state_process(skb);
 671         }
 672 }
 673
 674 /*
 675  *      llc_station_rcv - send received pdu to the station state machine
 676  *      @skb: received frame.
 677  *
 678  *      Sends data unit to station state machine.
 679  */
 680 static void llc_station_rcv(struct sk_buff *skb)
 681 {
 682         struct llc_station_state_ev *ev = llc_station_ev(skb);
 683
 684         ev->type   = LLC_STATION_EV_TYPE_PDU;
 685         ev->reason = 0;
 686         llc_station_state_process(skb);
 687 }
 688
 689 int __init llc_station_init(void)
 690 {
 691         u16 rc = -ENOBUFS;
 692         struct sk_buff *skb;
 693         struct llc_station_state_ev *ev;
 694
 695         skb_queue_head_init(&llc_main_station.mac_pdu_q);
 696         skb_queue_head_init(&llc_main_station.ev_q.list);
 697         spin_lock_init(&llc_main_station.ev_q.lock);
 698         setup_timer(&llc_main_station.ack_timer, llc_station_ack_tmr_cb,
 699                         (unsigned long)&llc_main_station);
 700         llc_main_station.ack_timer.expires  = jiffies +
 701                                                 sysctl_llc_station_ack_timeout;
 702         skb = alloc_skb(0, GFP_ATOMIC);
 703         if (!skb)
 704                 goto out;
 705         rc = 0;
 706         llc_set_station_handler(llc_station_rcv);
 707         ev = llc_station_ev(skb);
 708         memset(ev, 0, sizeof(*ev));
 709         llc_main_station.maximum_retry  = 1;
 710         llc_main_station.state          = LLC_STATION_STATE_DOWN;
 711         ev->type        = LLC_STATION_EV_TYPE_SIMPLE;
 712         ev->prim_type   = LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK;
 713         rc = llc_station_next_state(skb);
 714 out:
 715         return rc;
 716 }
 717
 718 void __exit llc_station_exit(void)
 719 {
 720         llc_set_station_handler(NULL);
 721 }