Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[linux-2.6.git] / 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/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 }