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