[PATCH] mark struct file_operations const 8
[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);
257
258         if (!nskb)
259                 goto out;
260         llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, 0, LLC_PDU_CMD);
261         llc_pdu_init_as_xid_cmd(nskb, LLC_XID_NULL_CLASS_2, 127);
262         rc = llc_mac_hdr_init(nskb, llc_station_mac_sa, llc_station_mac_sa);
263         if (unlikely(rc))
264                 goto free;
265         llc_station_send_pdu(nskb);
266 out:
267         return rc;
268 free:
269         kfree_skb(skb);
270         goto out;
271 }
272
273 static int llc_station_ac_send_xid_r(struct sk_buff *skb)
274 {
275         u8 mac_da[ETH_ALEN], dsap;
276         int rc = 1;
277         struct sk_buff* nskb = llc_alloc_frame(NULL, skb->dev);
278
279         if (!nskb)
280                 goto out;
281         rc = 0;
282         llc_pdu_decode_sa(skb, mac_da);
283         llc_pdu_decode_ssap(skb, &dsap);
284         llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
285         llc_pdu_init_as_xid_rsp(nskb, LLC_XID_NULL_CLASS_2, 127);
286         rc = llc_mac_hdr_init(nskb, llc_station_mac_sa, mac_da);
287         if (unlikely(rc))
288                 goto free;
289         llc_station_send_pdu(nskb);
290 out:
291         return rc;
292 free:
293         kfree_skb(skb);
294         goto out;
295 }
296
297 static int llc_station_ac_send_test_r(struct sk_buff *skb)
298 {
299         u8 mac_da[ETH_ALEN], dsap;
300         int rc = 1;
301         struct sk_buff *nskb = llc_alloc_frame(NULL, skb->dev);
302
303         if (!nskb)
304                 goto out;
305         rc = 0;
306         llc_pdu_decode_sa(skb, mac_da);
307         llc_pdu_decode_ssap(skb, &dsap);
308         llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
309         llc_pdu_init_as_test_rsp(nskb, skb);
310         rc = llc_mac_hdr_init(nskb, llc_station_mac_sa, mac_da);
311         if (unlikely(rc))
312                 goto free;
313         llc_station_send_pdu(nskb);
314 out:
315         return rc;
316 free:
317         kfree_skb(skb);
318         goto out;
319 }
320
321 static int llc_station_ac_report_status(struct sk_buff *skb)
322 {
323         return 0;
324 }
325
326 /* COMMON STATION STATE transitions */
327
328 /* dummy last-transition indicator; common to all state transition groups
329  * last entry for this state
330  * all members are zeros, .bss zeroes it
331  */
332 static struct llc_station_state_trans llc_stat_state_trans_end;
333
334 /* DOWN STATE transitions */
335
336 /* state transition for LLC_STATION_EV_ENABLE_WITH_DUP_ADDR_CHECK event */
337 static llc_station_action_t llc_stat_down_state_actions_1[] = {
338         [0] = llc_station_ac_start_ack_timer,
339         [1] = llc_station_ac_set_retry_cnt_0,
340         [2] = llc_station_ac_set_xid_r_cnt_0,
341         [3] = llc_station_ac_send_null_dsap_xid_c,
342         [4] = NULL,
343 };
344
345 static struct llc_station_state_trans llc_stat_down_state_trans_1 = {
346         .ev         = llc_stat_ev_enable_with_dup_addr_check,
347         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
348         .ev_actions = llc_stat_down_state_actions_1,
349 };
350
351 /* state transition for LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK event */
352 static llc_station_action_t llc_stat_down_state_actions_2[] = {
353         [0] = llc_station_ac_report_status,     /* STATION UP */
354         [1] = NULL,
355 };
356
357 static struct llc_station_state_trans llc_stat_down_state_trans_2 = {
358         .ev         = llc_stat_ev_enable_without_dup_addr_check,
359         .next_state = LLC_STATION_STATE_UP,
360         .ev_actions = llc_stat_down_state_actions_2,
361 };
362
363 /* array of pointers; one to each transition */
364 static struct llc_station_state_trans *llc_stat_dwn_state_trans[] = {
365         [0] = &llc_stat_down_state_trans_1,
366         [1] = &llc_stat_down_state_trans_2,
367         [2] = &llc_stat_state_trans_end,
368 };
369
370 /* UP STATE transitions */
371 /* state transition for LLC_STATION_EV_DISABLE_REQ event */
372 static llc_station_action_t llc_stat_up_state_actions_1[] = {
373         [0] = llc_station_ac_report_status,     /* STATION DOWN */
374         [1] = NULL,
375 };
376
377 static struct llc_station_state_trans llc_stat_up_state_trans_1 = {
378         .ev         = llc_stat_ev_disable_req,
379         .next_state = LLC_STATION_STATE_DOWN,
380         .ev_actions = llc_stat_up_state_actions_1,
381 };
382
383 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_XID_C event */
384 static llc_station_action_t llc_stat_up_state_actions_2[] = {
385         [0] = llc_station_ac_send_xid_r,
386         [1] = NULL,
387 };
388
389 static struct llc_station_state_trans llc_stat_up_state_trans_2 = {
390         .ev         = llc_stat_ev_rx_null_dsap_xid_c,
391         .next_state = LLC_STATION_STATE_UP,
392         .ev_actions = llc_stat_up_state_actions_2,
393 };
394
395 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_TEST_C event */
396 static llc_station_action_t llc_stat_up_state_actions_3[] = {
397         [0] = llc_station_ac_send_test_r,
398         [1] = NULL,
399 };
400
401 static struct llc_station_state_trans llc_stat_up_state_trans_3 = {
402         .ev         = llc_stat_ev_rx_null_dsap_test_c,
403         .next_state = LLC_STATION_STATE_UP,
404         .ev_actions = llc_stat_up_state_actions_3,
405 };
406
407 /* array of pointers; one to each transition */
408 static struct llc_station_state_trans *llc_stat_up_state_trans [] = {
409         [0] = &llc_stat_up_state_trans_1,
410         [1] = &llc_stat_up_state_trans_2,
411         [2] = &llc_stat_up_state_trans_3,
412         [3] = &llc_stat_state_trans_end,
413 };
414
415 /* DUP ADDR CHK STATE transitions */
416 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_0_XID_R_XID_R_CNT_EQ
417  * event
418  */
419 static llc_station_action_t llc_stat_dupaddr_state_actions_1[] = {
420         [0] = llc_station_ac_inc_xid_r_cnt_by_1,
421         [1] = NULL,
422 };
423
424 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_1 = {
425         .ev         = llc_stat_ev_rx_null_dsap_0_xid_r_xid_r_cnt_eq,
426         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
427         .ev_actions = llc_stat_dupaddr_state_actions_1,
428 };
429
430 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_1_XID_R_XID_R_CNT_EQ
431  * event
432  */
433 static llc_station_action_t llc_stat_dupaddr_state_actions_2[] = {
434         [0] = llc_station_ac_report_status,     /* DUPLICATE ADDRESS FOUND */
435         [1] = NULL,
436 };
437
438 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_2 = {
439         .ev         = llc_stat_ev_rx_null_dsap_1_xid_r_xid_r_cnt_eq,
440         .next_state = LLC_STATION_STATE_DOWN,
441         .ev_actions = llc_stat_dupaddr_state_actions_2,
442 };
443
444 /* state transition for LLC_STATION_EV_RX_NULL_DSAP_XID_C event */
445 static llc_station_action_t llc_stat_dupaddr_state_actions_3[] = {
446         [0] = llc_station_ac_send_xid_r,
447         [1] = NULL,
448 };
449
450 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_3 = {
451         .ev         = llc_stat_ev_rx_null_dsap_xid_c,
452         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
453         .ev_actions = llc_stat_dupaddr_state_actions_3,
454 };
455
456 /* state transition for LLC_STATION_EV_ACK_TMR_EXP_LT_RETRY_CNT_MAX_RETRY
457  * event
458  */
459 static llc_station_action_t llc_stat_dupaddr_state_actions_4[] = {
460         [0] = llc_station_ac_start_ack_timer,
461         [1] = llc_station_ac_inc_retry_cnt_by_1,
462         [2] = llc_station_ac_set_xid_r_cnt_0,
463         [3] = llc_station_ac_send_null_dsap_xid_c,
464         [4] = NULL,
465 };
466
467 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_4 = {
468         .ev         = llc_stat_ev_ack_tmr_exp_lt_retry_cnt_max_retry,
469         .next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
470         .ev_actions = llc_stat_dupaddr_state_actions_4,
471 };
472
473 /* state transition for LLC_STATION_EV_ACK_TMR_EXP_EQ_RETRY_CNT_MAX_RETRY
474  * event
475  */
476 static llc_station_action_t llc_stat_dupaddr_state_actions_5[] = {
477         [0] = llc_station_ac_report_status,     /* STATION UP */
478         [1] = NULL,
479 };
480
481 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_5 = {
482         .ev         = llc_stat_ev_ack_tmr_exp_eq_retry_cnt_max_retry,
483         .next_state = LLC_STATION_STATE_UP,
484         .ev_actions = llc_stat_dupaddr_state_actions_5,
485 };
486
487 /* state transition for LLC_STATION_EV_DISABLE_REQ event */
488 static llc_station_action_t llc_stat_dupaddr_state_actions_6[] = {
489         [0] = llc_station_ac_report_status,     /* STATION DOWN */
490         [1] = NULL,
491 };
492
493 static struct llc_station_state_trans llc_stat_dupaddr_state_trans_6 = {
494         .ev         = llc_stat_ev_disable_req,
495         .next_state = LLC_STATION_STATE_DOWN,
496         .ev_actions = llc_stat_dupaddr_state_actions_6,
497 };
498
499 /* array of pointers; one to each transition */
500 static struct llc_station_state_trans *llc_stat_dupaddr_state_trans[] = {
501         [0] = &llc_stat_dupaddr_state_trans_6,  /* Request */
502         [1] = &llc_stat_dupaddr_state_trans_4,  /* Timer */
503         [2] = &llc_stat_dupaddr_state_trans_5,
504         [3] = &llc_stat_dupaddr_state_trans_1,  /* Receive frame */
505         [4] = &llc_stat_dupaddr_state_trans_2,
506         [5] = &llc_stat_dupaddr_state_trans_3,
507         [6] = &llc_stat_state_trans_end,
508 };
509
510 static struct llc_station_state
511                         llc_station_state_table[LLC_NBR_STATION_STATES] = {
512         [LLC_STATION_STATE_DOWN - 1] = {
513                 .curr_state  = LLC_STATION_STATE_DOWN,
514                 .transitions = llc_stat_dwn_state_trans,
515         },
516         [LLC_STATION_STATE_DUP_ADDR_CHK - 1] = {
517                 .curr_state  = LLC_STATION_STATE_DUP_ADDR_CHK,
518                 .transitions = llc_stat_dupaddr_state_trans,
519         },
520         [LLC_STATION_STATE_UP - 1] = {
521                 .curr_state  = LLC_STATION_STATE_UP,
522                 .transitions = llc_stat_up_state_trans,
523         },
524 };
525
526 /**
527  *      llc_exec_station_trans_actions - executes actions for transition
528  *      @trans: Address of the transition
529  *      @skb: Address of the event that caused the transition
530  *
531  *      Executes actions of a transition of the station state machine. Returns
532  *      0 if all actions complete successfully, nonzero otherwise.
533  */
534 static u16 llc_exec_station_trans_actions(struct llc_station_state_trans *trans,
535                                           struct sk_buff *skb)
536 {
537         u16 rc = 0;
538         llc_station_action_t *next_action = trans->ev_actions;
539
540         for (; next_action && *next_action; next_action++)
541                 if ((*next_action)(skb))
542                         rc = 1;
543         return rc;
544 }
545
546 /**
547  *      llc_find_station_trans - finds transition for this event
548  *      @skb: Address of the event
549  *
550  *      Search thru events of the current state of the station until list
551  *      exhausted or it's obvious that the event is not valid for the current
552  *      state. Returns the address of the transition if cound, %NULL otherwise.
553  */
554 static struct llc_station_state_trans *
555                                 llc_find_station_trans(struct sk_buff *skb)
556 {
557         int i = 0;
558         struct llc_station_state_trans *rc = NULL;
559         struct llc_station_state_trans **next_trans;
560         struct llc_station_state *curr_state =
561                                 &llc_station_state_table[llc_main_station.state - 1];
562
563         for (next_trans = curr_state->transitions; next_trans[i]->ev; i++)
564                 if (!next_trans[i]->ev(skb)) {
565                         rc = next_trans[i];
566                         break;
567                 }
568         return rc;
569 }
570
571 /**
572  *      llc_station_free_ev - frees an event
573  *      @skb: Address of the event
574  *
575  *      Frees an event.
576  */
577 static void llc_station_free_ev(struct sk_buff *skb)
578 {
579         struct llc_station_state_ev *ev = llc_station_ev(skb);
580
581         if (ev->type == LLC_STATION_EV_TYPE_PDU)
582                 kfree_skb(skb);
583 }
584
585 /**
586  *      llc_station_next_state - processes event and goes to the next state
587  *      @skb: Address of the event
588  *
589  *      Processes an event, executes any transitions related to that event and
590  *      updates the state of the station.
591  */
592 static u16 llc_station_next_state(struct sk_buff *skb)
593 {
594         u16 rc = 1;
595         struct llc_station_state_trans *trans;
596
597         if (llc_main_station.state > LLC_NBR_STATION_STATES)
598                 goto out;
599         trans = llc_find_station_trans(skb);
600         if (trans) {
601                 /* got the state to which we next transition; perform the
602                  * actions associated with this transition before actually
603                  * transitioning to the next state
604                  */
605                 rc = llc_exec_station_trans_actions(trans, skb);
606                 if (!rc)
607                         /* transition station to next state if all actions
608                          * execute successfully; done; wait for next event
609                          */
610                         llc_main_station.state = trans->next_state;
611         } else
612                 /* event not recognized in current state; re-queue it for
613                  * processing again at a later time; return failure
614                  */
615                 rc = 0;
616 out:
617         llc_station_free_ev(skb);
618         return rc;
619 }
620
621 /**
622  *      llc_station_service_events - service events in the queue
623  *
624  *      Get an event from the station event queue (if any); attempt to service
625  *      the event; if event serviced, get the next event (if any) on the event
626  *      queue; if event not service, re-queue the event on the event queue and
627  *      attempt to service the next event; when serviced all events in queue,
628  *      finished; if don't transition to different state, just service all
629  *      events once; if transition to new state, service all events again.
630  *      Caller must hold llc_main_station.ev_q.lock.
631  */
632 static void llc_station_service_events(void)
633 {
634         struct sk_buff *skb;
635
636         while ((skb = skb_dequeue(&llc_main_station.ev_q.list)) != NULL)
637                 llc_station_next_state(skb);
638 }
639
640 /**
641  *      llc_station_state_process: queue event and try to process queue.
642  *      @skb: Address of the event
643  *
644  *      Queues an event (on the station event queue) for handling by the
645  *      station state machine and attempts to process any queued-up events.
646  */
647 static void llc_station_state_process(struct sk_buff *skb)
648 {
649         spin_lock_bh(&llc_main_station.ev_q.lock);
650         skb_queue_tail(&llc_main_station.ev_q.list, skb);
651         llc_station_service_events();
652         spin_unlock_bh(&llc_main_station.ev_q.lock);
653 }
654
655 static void llc_station_ack_tmr_cb(unsigned long timeout_data)
656 {
657         struct sk_buff *skb = alloc_skb(0, GFP_ATOMIC);
658
659         if (skb) {
660                 struct llc_station_state_ev *ev = llc_station_ev(skb);
661
662                 ev->type = LLC_STATION_EV_TYPE_ACK_TMR;
663                 llc_station_state_process(skb);
664         }
665 }
666
667 /*
668  *      llc_station_rcv - send received pdu to the station state machine
669  *      @skb: received frame.
670  *
671  *      Sends data unit to station state machine.
672  */
673 static void llc_station_rcv(struct sk_buff *skb)
674 {
675         struct llc_station_state_ev *ev = llc_station_ev(skb);
676
677         ev->type   = LLC_STATION_EV_TYPE_PDU;
678         ev->reason = 0;
679         llc_station_state_process(skb);
680 }
681
682 int __init llc_station_init(void)
683 {
684         u16 rc = -ENOBUFS;
685         struct sk_buff *skb;
686         struct llc_station_state_ev *ev;
687
688         skb_queue_head_init(&llc_main_station.mac_pdu_q);
689         skb_queue_head_init(&llc_main_station.ev_q.list);
690         spin_lock_init(&llc_main_station.ev_q.lock);
691         init_timer(&llc_main_station.ack_timer);
692         llc_main_station.ack_timer.data     = (unsigned long)&llc_main_station;
693         llc_main_station.ack_timer.function = llc_station_ack_tmr_cb;
694         llc_main_station.ack_timer.expires  = jiffies +
695                                                 sysctl_llc_station_ack_timeout;
696         skb = alloc_skb(0, GFP_ATOMIC);
697         if (!skb)
698                 goto out;
699         rc = 0;
700         llc_set_station_handler(llc_station_rcv);
701         ev = llc_station_ev(skb);
702         memset(ev, 0, sizeof(*ev));
703         llc_main_station.maximum_retry  = 1;
704         llc_main_station.state          = LLC_STATION_STATE_DOWN;
705         ev->type        = LLC_STATION_EV_TYPE_SIMPLE;
706         ev->prim_type   = LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK;
707         rc = llc_station_next_state(skb);
708 out:
709         return rc;
710 }
711
712 void __exit llc_station_exit(void)
713 {
714         llc_set_station_handler(NULL);
715 }