bluetooth: hid: make Android code conditional
[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 <linux/slab.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, LLC_PDU_TYPE_U,
258                                                sizeof(struct llc_xid_info));
259
260         if (!nskb)
261                 goto out;
262         llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, 0, LLC_PDU_CMD);
263         llc_pdu_init_as_xid_cmd(nskb, LLC_XID_NULL_CLASS_2, 127);
264         rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, skb->dev->dev_addr);
265         if (unlikely(rc))
266                 goto free;
267         llc_station_send_pdu(nskb);
268 out:
269         return rc;
270 free:
271         kfree_skb(skb);
272         goto out;
273 }
274
275 static int llc_station_ac_send_xid_r(struct sk_buff *skb)
276 {
277         u8 mac_da[ETH_ALEN], dsap;
278         int rc = 1;
279         struct sk_buff *nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U,
280                                                sizeof(struct llc_xid_info));
281
282         if (!nskb)
283                 goto out;
284         rc = 0;
285         llc_pdu_decode_sa(skb, mac_da);
286         llc_pdu_decode_ssap(skb, &dsap);
287         llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
288         llc_pdu_init_as_xid_rsp(nskb, LLC_XID_NULL_CLASS_2, 127);
289         rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);
290         if (unlikely(rc))
291                 goto free;
292         llc_station_send_pdu(nskb);
293 out:
294         return rc;
295 free:
296         kfree_skb(skb);
297         goto out;
298 }
299
300 static int llc_station_ac_send_test_r(struct sk_buff *skb)
301 {
302         u8 mac_da[ETH_ALEN], dsap;
303         int rc = 1;
304         u32 data_size;
305         struct sk_buff *nskb;
306
307         /* The test request command is type U (llc_len = 3) */
308         data_size = ntohs(eth_hdr(skb)->h_proto) - 3;
309         nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U, data_size);
310
311         if (!nskb)
312                 goto out;
313         rc = 0;
314         llc_pdu_decode_sa(skb, mac_da);
315         llc_pdu_decode_ssap(skb, &dsap);
316         llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
317         llc_pdu_init_as_test_rsp(nskb, skb);
318         rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);
319         if (unlikely(rc))
320                 goto free;
321         llc_station_send_pdu(nskb);
322 out:
323         return rc;
324 free:
325         kfree_skb(skb);
326         goto out;
327 }
328
329 static int llc_station_ac_report_status(struct sk_buff *skb)
330 {
331         return 0;
332 }
333
334 /* COMMON STATION STATE transitions */
335
336 /* dummy last-transition indicator; common to all state transition groups
337  * last entry for this state
338  * all members are zeros, .bss zeroes it
339  */
340 static struct llc_station_state_trans llc_stat_state_trans_end;
341
342 /* DOWN STATE transitions */
343
344 /* state transition for LLC_STATION_EV_ENABLE_WITH_DUP_ADDR_CHECK event */
345 static llc_station_action_t llc_stat_down_state_actions_1[] = {
346         [0] = llc_station_ac_start_ack_timer,
347         [1] = llc_station_ac_set_retry_cnt_0,
348         [2] = llc_station_ac_set_xid_r_cnt_0,
349         [3] = llc_station_ac_send_null_dsap_xid_c,
350         [4] = NULL,
351 };
352
353 static struct llc_station_state_trans llc_stat_down_state_trans_1 = {
354         .ev         = llc_stat_ev_enable_with_dup_addr_check,
355         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
356         .ev_actions = llc_stat_down_state_actions_1,
357 };
358
359 /* state transition for LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK event */
360 static llc_station_action_t llc_stat_down_state_actions_2[] = {
361         [0] = llc_station_ac_report_status,     /* STATION UP */
362         [1] = NULL,
363 };
364
365 static struct llc_station_state_trans llc_stat_down_state_trans_2 = {
366         .ev         = llc_stat_ev_enable_without_dup_addr_check,
367         .next_state = LLC_STATION_STATE_UP,
368         .ev_actions = llc_stat_down_state_actions_2,
369 };
370
371 /* array of pointers; one to each transition */
372 static struct llc_station_state_trans *llc_stat_dwn_state_trans[] = {
373         [0] = &llc_stat_down_state_trans_1,
374         [1] = &llc_stat_down_state_trans_2,
375         [2] = &llc_stat_state_trans_end,
376 };
377
378 /* UP STATE transitions */
379 /* state transition for LLC_STATION_EV_DISABLE_REQ event */
380 static llc_station_action_t llc_stat_up_state_actions_1[] = {
381         [0] = llc_station_ac_report_status,     /* STATION DOWN */
382         [1] = NULL,
383 };
384
385 static struct llc_station_state_trans llc_stat_up_state_trans_1 = {
386         .ev         = llc_stat_ev_disable_req,
387         .next_state = LLC_STATION_STATE_DOWN,
388         .ev_actions = llc_stat_up_state_actions_1,
389 };
390
391 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_XID_C event */
392 static llc_station_action_t llc_stat_up_state_actions_2[] = {
393         [0] = llc_station_ac_send_xid_r,
394         [1] = NULL,
395 };
396
397 static struct llc_station_state_trans llc_stat_up_state_trans_2 = {
398         .ev         = llc_stat_ev_rx_null_dsap_xid_c,
399         .next_state = LLC_STATION_STATE_UP,
400         .ev_actions = llc_stat_up_state_actions_2,
401 };
402
403 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_TEST_C event */
404 static llc_station_action_t llc_stat_up_state_actions_3[] = {
405         [0] = llc_station_ac_send_test_r,
406         [1] = NULL,
407 };
408
409 static struct llc_station_state_trans llc_stat_up_state_trans_3 = {
410         .ev         = llc_stat_ev_rx_null_dsap_test_c,
411         .next_state = LLC_STATION_STATE_UP,
412         .ev_actions = llc_stat_up_state_actions_3,
413 };
414
415 /* array of pointers; one to each transition */
416 static struct llc_station_state_trans *llc_stat_up_state_trans [] = {
417         [0] = &llc_stat_up_state_trans_1,
418         [1] = &llc_stat_up_state_trans_2,
419         [2] = &llc_stat_up_state_trans_3,
420         [3] = &llc_stat_state_trans_end,
421 };
422
423 /* DUP ADDR CHK STATE transitions */
424 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_0_XID_R_XID_R_CNT_EQ
425  * event
426  */
427 static llc_station_action_t llc_stat_dupaddr_state_actions_1[] = {
428         [0] = llc_station_ac_inc_xid_r_cnt_by_1,
429         [1] = NULL,
430 };
431
432 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_1 = {
433         .ev         = llc_stat_ev_rx_null_dsap_0_xid_r_xid_r_cnt_eq,
434         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
435         .ev_actions = llc_stat_dupaddr_state_actions_1,
436 };
437
438 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_1_XID_R_XID_R_CNT_EQ
439  * event
440  */
441 static llc_station_action_t llc_stat_dupaddr_state_actions_2[] = {
442         [0] = llc_station_ac_report_status,     /* DUPLICATE ADDRESS FOUND */
443         [1] = NULL,
444 };
445
446 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_2 = {
447         .ev         = llc_stat_ev_rx_null_dsap_1_xid_r_xid_r_cnt_eq,
448         .next_state = LLC_STATION_STATE_DOWN,
449         .ev_actions = llc_stat_dupaddr_state_actions_2,
450 };
451
452 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_XID_C event */
453 static llc_station_action_t llc_stat_dupaddr_state_actions_3[] = {
454         [0] = llc_station_ac_send_xid_r,
455         [1] = NULL,
456 };
457
458 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_3 = {
459         .ev         = llc_stat_ev_rx_null_dsap_xid_c,
460         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
461         .ev_actions = llc_stat_dupaddr_state_actions_3,
462 };
463
464 /* state transition for LLC_STATION_EV_ACK_TMR_EXP_LT_RETRY_CNT_MAX_RETRY
465  * event
466  */
467 static llc_station_action_t llc_stat_dupaddr_state_actions_4[] = {
468         [0] = llc_station_ac_start_ack_timer,
469         [1] = llc_station_ac_inc_retry_cnt_by_1,
470         [2] = llc_station_ac_set_xid_r_cnt_0,
471         [3] = llc_station_ac_send_null_dsap_xid_c,
472         [4] = NULL,
473 };
474
475 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_4 = {
476         .ev         = llc_stat_ev_ack_tmr_exp_lt_retry_cnt_max_retry,
477         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
478         .ev_actions = llc_stat_dupaddr_state_actions_4,
479 };
480
481 /* state transition for LLC_STATION_EV_ACK_TMR_EXP_EQ_RETRY_CNT_MAX_RETRY
482  * event
483  */
484 static llc_station_action_t llc_stat_dupaddr_state_actions_5[] = {
485         [0] = llc_station_ac_report_status,     /* STATION UP */
486         [1] = NULL,
487 };
488
489 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_5 = {
490         .ev         = llc_stat_ev_ack_tmr_exp_eq_retry_cnt_max_retry,
491         .next_state = LLC_STATION_STATE_UP,
492         .ev_actions = llc_stat_dupaddr_state_actions_5,
493 };
494
495 /* state transition for LLC_STATION_EV_DISABLE_REQ event */
496 static llc_station_action_t llc_stat_dupaddr_state_actions_6[] = {
497         [0] = llc_station_ac_report_status,     /* STATION DOWN */
498         [1] = NULL,
499 };
500
501 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_6 = {
502         .ev         = llc_stat_ev_disable_req,
503         .next_state = LLC_STATION_STATE_DOWN,
504         .ev_actions = llc_stat_dupaddr_state_actions_6,
505 };
506
507 /* array of pointers; one to each transition */
508 static struct llc_station_state_trans *llc_stat_dupaddr_state_trans[] = {
509         [0] = &llc_stat_dupaddr_state_trans_6,  /* Request */
510         [1] = &llc_stat_dupaddr_state_trans_4,  /* Timer */
511         [2] = &llc_stat_dupaddr_state_trans_5,
512         [3] = &llc_stat_dupaddr_state_trans_1,  /* Receive frame */
513         [4] = &llc_stat_dupaddr_state_trans_2,
514         [5] = &llc_stat_dupaddr_state_trans_3,
515         [6] = &llc_stat_state_trans_end,
516 };
517
518 static struct llc_station_state
519                         llc_station_state_table[LLC_NBR_STATION_STATES] = {
520         [LLC_STATION_STATE_DOWN - 1] = {
521                 .curr_state  = LLC_STATION_STATE_DOWN,
522                 .transitions = llc_stat_dwn_state_trans,
523         },
524         [LLC_STATION_STATE_DUP_ADDR_CHK - 1] = {
525                 .curr_state  = LLC_STATION_STATE_DUP_ADDR_CHK,
526                 .transitions = llc_stat_dupaddr_state_trans,
527         },
528         [LLC_STATION_STATE_UP - 1] = {
529                 .curr_state  = LLC_STATION_STATE_UP,
530                 .transitions = llc_stat_up_state_trans,
531         },
532 };
533
534 /**
535  *      llc_exec_station_trans_actions - executes actions for transition
536  *      @trans: Address of the transition
537  *      @skb: Address of the event that caused the transition
538  *
539  *      Executes actions of a transition of the station state machine. Returns
540  *      0 if all actions complete successfully, nonzero otherwise.
541  */
542 static u16 llc_exec_station_trans_actions(struct llc_station_state_trans *trans,
543                                           struct sk_buff *skb)
544 {
545         u16 rc = 0;
546         llc_station_action_t *next_action = trans->ev_actions;
547
548         for (; next_action && *next_action; next_action++)
549                 if ((*next_action)(skb))
550                         rc = 1;
551         return rc;
552 }
553
554 /**
555  *      llc_find_station_trans - finds transition for this event
556  *      @skb: Address of the event
557  *
558  *      Search thru events of the current state of the station until list
559  *      exhausted or it's obvious that the event is not valid for the current
560  *      state. Returns the address of the transition if cound, %NULL otherwise.
561  */
562 static struct llc_station_state_trans *
563                                 llc_find_station_trans(struct sk_buff *skb)
564 {
565         int i = 0;
566         struct llc_station_state_trans *rc = NULL;
567         struct llc_station_state_trans **next_trans;
568         struct llc_station_state *curr_state =
569                                 &llc_station_state_table[llc_main_station.state - 1];
570
571         for (next_trans = curr_state->transitions; next_trans[i]->ev; i++)
572                 if (!next_trans[i]->ev(skb)) {
573                         rc = next_trans[i];
574                         break;
575                 }
576         return rc;
577 }
578
579 /**
580  *      llc_station_free_ev - frees an event
581  *      @skb: Address of the event
582  *
583  *      Frees an event.
584  */
585 static void llc_station_free_ev(struct sk_buff *skb)
586 {
587         struct llc_station_state_ev *ev = llc_station_ev(skb);
588
589         if (ev->type == LLC_STATION_EV_TYPE_PDU)
590                 kfree_skb(skb);
591 }
592
593 /**
594  *      llc_station_next_state - processes event and goes to the next state
595  *      @skb: Address of the event
596  *
597  *      Processes an event, executes any transitions related to that event and
598  *      updates the state of the station.
599  */
600 static u16 llc_station_next_state(struct sk_buff *skb)
601 {
602         u16 rc = 1;
603         struct llc_station_state_trans *trans;
604
605         if (llc_main_station.state > LLC_NBR_STATION_STATES)
606                 goto out;
607         trans = llc_find_station_trans(skb);
608         if (trans) {
609                 /* got the state to which we next transition; perform the
610                  * actions associated with this transition before actually
611                  * transitioning to the next state
612                  */
613                 rc = llc_exec_station_trans_actions(trans, skb);
614                 if (!rc)
615                         /* transition station to next state if all actions
616                          * execute successfully; done; wait for next event
617                          */
618                         llc_main_station.state = trans->next_state;
619         } else
620                 /* event not recognized in current state; re-queue it for
621                  * processing again at a later time; return failure
622                  */
623                 rc = 0;
624 out:
625         llc_station_free_ev(skb);
626         return rc;
627 }
628
629 /**
630  *      llc_station_service_events - service events in the queue
631  *
632  *      Get an event from the station event queue (if any); attempt to service
633  *      the event; if event serviced, get the next event (if any) on the event
634  *      queue; if event not service, re-queue the event on the event queue and
635  *      attempt to service the next event; when serviced all events in queue,
636  *      finished; if don't transition to different state, just service all
637  *      events once; if transition to new state, service all events again.
638  *      Caller must hold llc_main_station.ev_q.lock.
639  */
640 static void llc_station_service_events(void)
641 {
642         struct sk_buff *skb;
643
644         while ((skb = skb_dequeue(&llc_main_station.ev_q.list)) != NULL)
645                 llc_station_next_state(skb);
646 }
647
648 /**
649  *      llc_station_state_process: queue event and try to process queue.
650  *      @skb: Address of the event
651  *
652  *      Queues an event (on the station event queue) for handling by the
653  *      station state machine and attempts to process any queued-up events.
654  */
655 static void llc_station_state_process(struct sk_buff *skb)
656 {
657         spin_lock_bh(&llc_main_station.ev_q.lock);
658         skb_queue_tail(&llc_main_station.ev_q.list, skb);
659         llc_station_service_events();
660         spin_unlock_bh(&llc_main_station.ev_q.lock);
661 }
662
663 static void llc_station_ack_tmr_cb(unsigned long timeout_data)
664 {
665         struct sk_buff *skb = alloc_skb(0, GFP_ATOMIC);
666
667         if (skb) {
668                 struct llc_station_state_ev *ev = llc_station_ev(skb);
669
670                 ev->type = LLC_STATION_EV_TYPE_ACK_TMR;
671                 llc_station_state_process(skb);
672         }
673 }
674
675 /*
676  *      llc_station_rcv - send received pdu to the station state machine
677  *      @skb: received frame.
678  *
679  *      Sends data unit to station state machine.
680  */
681 static void llc_station_rcv(struct sk_buff *skb)
682 {
683         struct llc_station_state_ev *ev = llc_station_ev(skb);
684
685         ev->type   = LLC_STATION_EV_TYPE_PDU;
686         ev->reason = 0;
687         llc_station_state_process(skb);
688 }
689
690 int __init llc_station_init(void)
691 {
692         int rc = -ENOBUFS;
693         struct sk_buff *skb;
694         struct llc_station_state_ev *ev;
695
696         skb_queue_head_init(&llc_main_station.mac_pdu_q);
697         skb_queue_head_init(&llc_main_station.ev_q.list);
698         spin_lock_init(&llc_main_station.ev_q.lock);
699         setup_timer(&llc_main_station.ack_timer, llc_station_ack_tmr_cb,
700                         (unsigned long)&llc_main_station);
701         llc_main_station.ack_timer.expires  = jiffies +
702                                                 sysctl_llc_station_ack_timeout;
703         skb = alloc_skb(0, GFP_ATOMIC);
704         if (!skb)
705                 goto out;
706         rc = 0;
707         llc_set_station_handler(llc_station_rcv);
708         ev = llc_station_ev(skb);
709         memset(ev, 0, sizeof(*ev));
710         llc_main_station.maximum_retry  = 1;
711         llc_main_station.state          = LLC_STATION_STATE_DOWN;
712         ev->type        = LLC_STATION_EV_TYPE_SIMPLE;
713         ev->prim_type   = LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK;
714         rc = llc_station_next_state(skb);
715 out:
716         return rc;
717 }
718
719 void __exit llc_station_exit(void)
720 {
721         llc_set_station_handler(NULL);
722 }