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