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 *
llc_station_ev(struct sk_buff * skb)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
llc_stat_ev_enable_with_dup_addr_check(struct sk_buff * skb)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
llc_stat_ev_enable_without_dup_addr_check(struct sk_buff * skb)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
llc_stat_ev_ack_tmr_exp_lt_retry_cnt_max_retry(struct sk_buff * skb)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
llc_stat_ev_ack_tmr_exp_eq_retry_cnt_max_retry(struct sk_buff * skb)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
llc_stat_ev_rx_null_dsap_xid_c(struct sk_buff * skb)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
llc_stat_ev_rx_null_dsap_0_xid_r_xid_r_cnt_eq(struct sk_buff * skb)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
llc_stat_ev_rx_null_dsap_1_xid_r_xid_r_cnt_eq(struct sk_buff * skb)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
llc_stat_ev_rx_null_dsap_test_c(struct sk_buff * skb)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
llc_stat_ev_disable_req(struct sk_buff * skb)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 */
llc_station_send_pdu(struct sk_buff * skb)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
llc_station_ac_start_ack_timer(struct sk_buff * skb)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
llc_station_ac_set_retry_cnt_0(struct sk_buff * skb)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
llc_station_ac_inc_retry_cnt_by_1(struct sk_buff * skb)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
llc_station_ac_set_xid_r_cnt_0(struct sk_buff * skb)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
llc_station_ac_inc_xid_r_cnt_by_1(struct sk_buff * skb)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
llc_station_ac_send_null_dsap_xid_c(struct sk_buff * skb)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
llc_station_ac_send_xid_r(struct sk_buff * skb)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
llc_station_ac_send_test_r(struct sk_buff * skb)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
llc_station_ac_report_status(struct sk_buff * skb)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 */
llc_exec_station_trans_actions(struct llc_station_state_trans * trans,struct sk_buff * skb)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 *
llc_find_station_trans(struct sk_buff * skb)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 */
llc_station_free_ev(struct sk_buff * skb)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 */
llc_station_next_state(struct sk_buff * skb)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 */
llc_station_service_events(void)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 */
llc_station_state_process(struct sk_buff * skb)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
llc_station_ack_tmr_cb(unsigned long timeout_data)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 */
llc_station_rcv(struct sk_buff * skb)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
llc_station_init(void)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
llc_station_exit(void)719 void __exit llc_station_exit(void)
720 {
721 llc_set_station_handler(NULL);
722 }
723