llc: use limited socket backlog
[linux-2.6.git] / net / llc / llc_conn.c
1 /*
2  * llc_conn.c - Driver routines for connection component.
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
15 #include <linux/init.h>
16 #include <net/llc_sap.h>
17 #include <net/llc_conn.h>
18 #include <net/sock.h>
19 #include <net/tcp_states.h>
20 #include <net/llc_c_ev.h>
21 #include <net/llc_c_ac.h>
22 #include <net/llc_c_st.h>
23 #include <net/llc_pdu.h>
24
25 #if 0
26 #define dprintk(args...) printk(KERN_DEBUG args)
27 #else
28 #define dprintk(args...)
29 #endif
30
31 static int llc_find_offset(int state, int ev_type);
32 static void llc_conn_send_pdus(struct sock *sk);
33 static int llc_conn_service(struct sock *sk, struct sk_buff *skb);
34 static int llc_exec_conn_trans_actions(struct sock *sk,
35                                        struct llc_conn_state_trans *trans,
36                                        struct sk_buff *ev);
37 static struct llc_conn_state_trans *llc_qualify_conn_ev(struct sock *sk,
38                                                         struct sk_buff *skb);
39
40 /* Offset table on connection states transition diagram */
41 static int llc_offset_table[NBR_CONN_STATES][NBR_CONN_EV];
42
43 int sysctl_llc2_ack_timeout = LLC2_ACK_TIME * HZ;
44 int sysctl_llc2_p_timeout = LLC2_P_TIME * HZ;
45 int sysctl_llc2_rej_timeout = LLC2_REJ_TIME * HZ;
46 int sysctl_llc2_busy_timeout = LLC2_BUSY_TIME * HZ;
47
48 /**
49  *      llc_conn_state_process - sends event to connection state machine
50  *      @sk: connection
51  *      @skb: occurred event
52  *
53  *      Sends an event to connection state machine. After processing event
54  *      (executing it's actions and changing state), upper layer will be
55  *      indicated or confirmed, if needed. Returns 0 for success, 1 for
56  *      failure. The socket lock has to be held before calling this function.
57  */
58 int llc_conn_state_process(struct sock *sk, struct sk_buff *skb)
59 {
60         int rc;
61         struct llc_sock *llc = llc_sk(skb->sk);
62         struct llc_conn_state_ev *ev = llc_conn_ev(skb);
63
64         /*
65          * We have to hold the skb, because llc_conn_service will kfree it in
66          * the sending path and we need to look at the skb->cb, where we encode
67          * llc_conn_state_ev.
68          */
69         skb_get(skb);
70         ev->ind_prim = ev->cfm_prim = 0;
71         /*
72          * Send event to state machine
73          */
74         rc = llc_conn_service(skb->sk, skb);
75         if (unlikely(rc != 0)) {
76                 printk(KERN_ERR "%s: llc_conn_service failed\n", __func__);
77                 goto out_kfree_skb;
78         }
79
80         if (unlikely(!ev->ind_prim && !ev->cfm_prim)) {
81                 /* indicate or confirm not required */
82                 if (!skb->next)
83                         goto out_kfree_skb;
84                 goto out_skb_put;
85         }
86
87         if (unlikely(ev->ind_prim && ev->cfm_prim)) /* Paranoia */
88                 skb_get(skb);
89
90         switch (ev->ind_prim) {
91         case LLC_DATA_PRIM:
92                 llc_save_primitive(sk, skb, LLC_DATA_PRIM);
93                 if (unlikely(sock_queue_rcv_skb(sk, skb))) {
94                         /*
95                          * shouldn't happen
96                          */
97                         printk(KERN_ERR "%s: sock_queue_rcv_skb failed!\n",
98                                __func__);
99                         kfree_skb(skb);
100                 }
101                 break;
102         case LLC_CONN_PRIM:
103                 /*
104                  * Can't be sock_queue_rcv_skb, because we have to leave the
105                  * skb->sk pointing to the newly created struct sock in
106                  * llc_conn_handler. -acme
107                  */
108                 skb_queue_tail(&sk->sk_receive_queue, skb);
109                 sk->sk_state_change(sk);
110                 break;
111         case LLC_DISC_PRIM:
112                 sock_hold(sk);
113                 if (sk->sk_type == SOCK_STREAM &&
114                     sk->sk_state == TCP_ESTABLISHED) {
115                         sk->sk_shutdown       = SHUTDOWN_MASK;
116                         sk->sk_socket->state  = SS_UNCONNECTED;
117                         sk->sk_state          = TCP_CLOSE;
118                         if (!sock_flag(sk, SOCK_DEAD)) {
119                                 sock_set_flag(sk, SOCK_DEAD);
120                                 sk->sk_state_change(sk);
121                         }
122                 }
123                 kfree_skb(skb);
124                 sock_put(sk);
125                 break;
126         case LLC_RESET_PRIM:
127                 /*
128                  * FIXME:
129                  * RESET is not being notified to upper layers for now
130                  */
131                 printk(KERN_INFO "%s: received a reset ind!\n", __func__);
132                 kfree_skb(skb);
133                 break;
134         default:
135                 if (ev->ind_prim) {
136                         printk(KERN_INFO "%s: received unknown %d prim!\n",
137                                 __func__, ev->ind_prim);
138                         kfree_skb(skb);
139                 }
140                 /* No indication */
141                 break;
142         }
143
144         switch (ev->cfm_prim) {
145         case LLC_DATA_PRIM:
146                 if (!llc_data_accept_state(llc->state))
147                         sk->sk_write_space(sk);
148                 else
149                         rc = llc->failed_data_req = 1;
150                 break;
151         case LLC_CONN_PRIM:
152                 if (sk->sk_type == SOCK_STREAM &&
153                     sk->sk_state == TCP_SYN_SENT) {
154                         if (ev->status) {
155                                 sk->sk_socket->state = SS_UNCONNECTED;
156                                 sk->sk_state         = TCP_CLOSE;
157                         } else {
158                                 sk->sk_socket->state = SS_CONNECTED;
159                                 sk->sk_state         = TCP_ESTABLISHED;
160                         }
161                         sk->sk_state_change(sk);
162                 }
163                 break;
164         case LLC_DISC_PRIM:
165                 sock_hold(sk);
166                 if (sk->sk_type == SOCK_STREAM && sk->sk_state == TCP_CLOSING) {
167                         sk->sk_socket->state = SS_UNCONNECTED;
168                         sk->sk_state         = TCP_CLOSE;
169                         sk->sk_state_change(sk);
170                 }
171                 sock_put(sk);
172                 break;
173         case LLC_RESET_PRIM:
174                 /*
175                  * FIXME:
176                  * RESET is not being notified to upper layers for now
177                  */
178                 printk(KERN_INFO "%s: received a reset conf!\n", __func__);
179                 break;
180         default:
181                 if (ev->cfm_prim) {
182                         printk(KERN_INFO "%s: received unknown %d prim!\n",
183                                         __func__, ev->cfm_prim);
184                         break;
185                 }
186                 goto out_skb_put; /* No confirmation */
187         }
188 out_kfree_skb:
189         kfree_skb(skb);
190 out_skb_put:
191         kfree_skb(skb);
192         return rc;
193 }
194
195 void llc_conn_send_pdu(struct sock *sk, struct sk_buff *skb)
196 {
197         /* queue PDU to send to MAC layer */
198         skb_queue_tail(&sk->sk_write_queue, skb);
199         llc_conn_send_pdus(sk);
200 }
201
202 /**
203  *      llc_conn_rtn_pdu - sends received data pdu to upper layer
204  *      @sk: Active connection
205  *      @skb: Received data frame
206  *
207  *      Sends received data pdu to upper layer (by using indicate function).
208  *      Prepares service parameters (prim and prim_data). calling indication
209  *      function will be done in llc_conn_state_process.
210  */
211 void llc_conn_rtn_pdu(struct sock *sk, struct sk_buff *skb)
212 {
213         struct llc_conn_state_ev *ev = llc_conn_ev(skb);
214
215         ev->ind_prim = LLC_DATA_PRIM;
216 }
217
218 /**
219  *      llc_conn_resend_i_pdu_as_cmd - resend all all unacknowledged I PDUs
220  *      @sk: active connection
221  *      @nr: NR
222  *      @first_p_bit: p_bit value of first pdu
223  *
224  *      Resend all unacknowledged I PDUs, starting with the NR; send first as
225  *      command PDU with P bit equal first_p_bit; if more than one send
226  *      subsequent as command PDUs with P bit equal zero (0).
227  */
228 void llc_conn_resend_i_pdu_as_cmd(struct sock *sk, u8 nr, u8 first_p_bit)
229 {
230         struct sk_buff *skb;
231         struct llc_pdu_sn *pdu;
232         u16 nbr_unack_pdus;
233         struct llc_sock *llc;
234         u8 howmany_resend = 0;
235
236         llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
237         if (!nbr_unack_pdus)
238                 goto out;
239         /*
240          * Process unack PDUs only if unack queue is not empty; remove
241          * appropriate PDUs, fix them up, and put them on mac_pdu_q.
242          */
243         llc = llc_sk(sk);
244
245         while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
246                 pdu = llc_pdu_sn_hdr(skb);
247                 llc_pdu_set_cmd_rsp(skb, LLC_PDU_CMD);
248                 llc_pdu_set_pf_bit(skb, first_p_bit);
249                 skb_queue_tail(&sk->sk_write_queue, skb);
250                 first_p_bit = 0;
251                 llc->vS = LLC_I_GET_NS(pdu);
252                 howmany_resend++;
253         }
254         if (howmany_resend > 0)
255                 llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
256         /* any PDUs to re-send are queued up; start sending to MAC */
257         llc_conn_send_pdus(sk);
258 out:;
259 }
260
261 /**
262  *      llc_conn_resend_i_pdu_as_rsp - Resend all unacknowledged I PDUs
263  *      @sk: active connection.
264  *      @nr: NR
265  *      @first_f_bit: f_bit value of first pdu.
266  *
267  *      Resend all unacknowledged I PDUs, starting with the NR; send first as
268  *      response PDU with F bit equal first_f_bit; if more than one send
269  *      subsequent as response PDUs with F bit equal zero (0).
270  */
271 void llc_conn_resend_i_pdu_as_rsp(struct sock *sk, u8 nr, u8 first_f_bit)
272 {
273         struct sk_buff *skb;
274         u16 nbr_unack_pdus;
275         struct llc_sock *llc = llc_sk(sk);
276         u8 howmany_resend = 0;
277
278         llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
279         if (!nbr_unack_pdus)
280                 goto out;
281         /*
282          * Process unack PDUs only if unack queue is not empty; remove
283          * appropriate PDUs, fix them up, and put them on mac_pdu_q
284          */
285         while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
286                 struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
287
288                 llc_pdu_set_cmd_rsp(skb, LLC_PDU_RSP);
289                 llc_pdu_set_pf_bit(skb, first_f_bit);
290                 skb_queue_tail(&sk->sk_write_queue, skb);
291                 first_f_bit = 0;
292                 llc->vS = LLC_I_GET_NS(pdu);
293                 howmany_resend++;
294         }
295         if (howmany_resend > 0)
296                 llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
297         /* any PDUs to re-send are queued up; start sending to MAC */
298         llc_conn_send_pdus(sk);
299 out:;
300 }
301
302 /**
303  *      llc_conn_remove_acked_pdus - Removes acknowledged pdus from tx queue
304  *      @sk: active connection
305  *      nr: NR
306  *      how_many_unacked: size of pdu_unack_q after removing acked pdus
307  *
308  *      Removes acknowledged pdus from transmit queue (pdu_unack_q). Returns
309  *      the number of pdus that removed from queue.
310  */
311 int llc_conn_remove_acked_pdus(struct sock *sk, u8 nr, u16 *how_many_unacked)
312 {
313         int pdu_pos, i;
314         struct sk_buff *skb;
315         struct llc_pdu_sn *pdu;
316         int nbr_acked = 0;
317         struct llc_sock *llc = llc_sk(sk);
318         int q_len = skb_queue_len(&llc->pdu_unack_q);
319
320         if (!q_len)
321                 goto out;
322         skb = skb_peek(&llc->pdu_unack_q);
323         pdu = llc_pdu_sn_hdr(skb);
324
325         /* finding position of last acked pdu in queue */
326         pdu_pos = ((int)LLC_2_SEQ_NBR_MODULO + (int)nr -
327                         (int)LLC_I_GET_NS(pdu)) % LLC_2_SEQ_NBR_MODULO;
328
329         for (i = 0; i < pdu_pos && i < q_len; i++) {
330                 skb = skb_dequeue(&llc->pdu_unack_q);
331                 kfree_skb(skb);
332                 nbr_acked++;
333         }
334 out:
335         *how_many_unacked = skb_queue_len(&llc->pdu_unack_q);
336         return nbr_acked;
337 }
338
339 /**
340  *      llc_conn_send_pdus - Sends queued PDUs
341  *      @sk: active connection
342  *
343  *      Sends queued pdus to MAC layer for transmission.
344  */
345 static void llc_conn_send_pdus(struct sock *sk)
346 {
347         struct sk_buff *skb;
348
349         while ((skb = skb_dequeue(&sk->sk_write_queue)) != NULL) {
350                 struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
351
352                 if (LLC_PDU_TYPE_IS_I(pdu) &&
353                     !(skb->dev->flags & IFF_LOOPBACK)) {
354                         struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
355
356                         skb_queue_tail(&llc_sk(sk)->pdu_unack_q, skb);
357                         if (!skb2)
358                                 break;
359                         skb = skb2;
360                 }
361                 dev_queue_xmit(skb);
362         }
363 }
364
365 /**
366  *      llc_conn_service - finds transition and changes state of connection
367  *      @sk: connection
368  *      @skb: happened event
369  *
370  *      This function finds transition that matches with happened event, then
371  *      executes related actions and finally changes state of connection.
372  *      Returns 0 for success, 1 for failure.
373  */
374 static int llc_conn_service(struct sock *sk, struct sk_buff *skb)
375 {
376         int rc = 1;
377         struct llc_sock *llc = llc_sk(sk);
378         struct llc_conn_state_trans *trans;
379
380         if (llc->state > NBR_CONN_STATES)
381                 goto out;
382         rc = 0;
383         trans = llc_qualify_conn_ev(sk, skb);
384         if (trans) {
385                 rc = llc_exec_conn_trans_actions(sk, trans, skb);
386                 if (!rc && trans->next_state != NO_STATE_CHANGE) {
387                         llc->state = trans->next_state;
388                         if (!llc_data_accept_state(llc->state))
389                                 sk->sk_state_change(sk);
390                 }
391         }
392 out:
393         return rc;
394 }
395
396 /**
397  *      llc_qualify_conn_ev - finds transition for event
398  *      @sk: connection
399  *      @skb: happened event
400  *
401  *      This function finds transition that matches with happened event.
402  *      Returns pointer to found transition on success, %NULL otherwise.
403  */
404 static struct llc_conn_state_trans *llc_qualify_conn_ev(struct sock *sk,
405                                                         struct sk_buff *skb)
406 {
407         struct llc_conn_state_trans **next_trans;
408         llc_conn_ev_qfyr_t *next_qualifier;
409         struct llc_conn_state_ev *ev = llc_conn_ev(skb);
410         struct llc_sock *llc = llc_sk(sk);
411         struct llc_conn_state *curr_state =
412                                         &llc_conn_state_table[llc->state - 1];
413
414         /* search thru events for this state until
415          * list exhausted or until no more
416          */
417         for (next_trans = curr_state->transitions +
418                 llc_find_offset(llc->state - 1, ev->type);
419              (*next_trans)->ev; next_trans++) {
420                 if (!((*next_trans)->ev)(sk, skb)) {
421                         /* got POSSIBLE event match; the event may require
422                          * qualification based on the values of a number of
423                          * state flags; if all qualifications are met (i.e.,
424                          * if all qualifying functions return success, or 0,
425                          * then this is THE event we're looking for
426                          */
427                         for (next_qualifier = (*next_trans)->ev_qualifiers;
428                              next_qualifier && *next_qualifier &&
429                              !(*next_qualifier)(sk, skb); next_qualifier++)
430                                 /* nothing */;
431                         if (!next_qualifier || !*next_qualifier)
432                                 /* all qualifiers executed successfully; this is
433                                  * our transition; return it so we can perform
434                                  * the associated actions & change the state
435                                  */
436                                 return *next_trans;
437                 }
438         }
439         return NULL;
440 }
441
442 /**
443  *      llc_exec_conn_trans_actions - executes related actions
444  *      @sk: connection
445  *      @trans: transition that it's actions must be performed
446  *      @skb: event
447  *
448  *      Executes actions that is related to happened event. Returns 0 for
449  *      success, 1 to indicate failure of at least one action.
450  */
451 static int llc_exec_conn_trans_actions(struct sock *sk,
452                                        struct llc_conn_state_trans *trans,
453                                        struct sk_buff *skb)
454 {
455         int rc = 0;
456         llc_conn_action_t *next_action;
457
458         for (next_action = trans->ev_actions;
459              next_action && *next_action; next_action++) {
460                 int rc2 = (*next_action)(sk, skb);
461
462                 if (rc2 == 2) {
463                         rc = rc2;
464                         break;
465                 } else if (rc2)
466                         rc = 1;
467         }
468         return rc;
469 }
470
471 static inline bool llc_estab_match(const struct llc_sap *sap,
472                                    const struct llc_addr *daddr,
473                                    const struct llc_addr *laddr,
474                                    const struct sock *sk)
475 {
476         struct llc_sock *llc = llc_sk(sk);
477
478         return llc->laddr.lsap == laddr->lsap &&
479                 llc->daddr.lsap == daddr->lsap &&
480                 llc_mac_match(llc->laddr.mac, laddr->mac) &&
481                 llc_mac_match(llc->daddr.mac, daddr->mac);
482 }
483
484 /**
485  *      __llc_lookup_established - Finds connection for the remote/local sap/mac
486  *      @sap: SAP
487  *      @daddr: address of remote LLC (MAC + SAP)
488  *      @laddr: address of local LLC (MAC + SAP)
489  *
490  *      Search connection list of the SAP and finds connection using the remote
491  *      mac, remote sap, local mac, and local sap. Returns pointer for
492  *      connection found, %NULL otherwise.
493  *      Caller has to make sure local_bh is disabled.
494  */
495 static struct sock *__llc_lookup_established(struct llc_sap *sap,
496                                              struct llc_addr *daddr,
497                                              struct llc_addr *laddr)
498 {
499         struct sock *rc;
500         struct hlist_nulls_node *node;
501         int slot = llc_sk_laddr_hashfn(sap, laddr);
502         struct hlist_nulls_head *laddr_hb = &sap->sk_laddr_hash[slot];
503
504         rcu_read_lock();
505 again:
506         sk_nulls_for_each_rcu(rc, node, laddr_hb) {
507                 if (llc_estab_match(sap, daddr, laddr, rc)) {
508                         /* Extra checks required by SLAB_DESTROY_BY_RCU */
509                         if (unlikely(!atomic_inc_not_zero(&rc->sk_refcnt)))
510                                 goto again;
511                         if (unlikely(llc_sk(rc)->sap != sap ||
512                                      !llc_estab_match(sap, daddr, laddr, rc))) {
513                                 sock_put(rc);
514                                 continue;
515                         }
516                         goto found;
517                 }
518         }
519         rc = NULL;
520         /*
521          * if the nulls value we got at the end of this lookup is
522          * not the expected one, we must restart lookup.
523          * We probably met an item that was moved to another chain.
524          */
525         if (unlikely(get_nulls_value(node) != slot))
526                 goto again;
527 found:
528         rcu_read_unlock();
529         return rc;
530 }
531
532 struct sock *llc_lookup_established(struct llc_sap *sap,
533                                     struct llc_addr *daddr,
534                                     struct llc_addr *laddr)
535 {
536         struct sock *sk;
537
538         local_bh_disable();
539         sk = __llc_lookup_established(sap, daddr, laddr);
540         local_bh_enable();
541         return sk;
542 }
543
544 static inline bool llc_listener_match(const struct llc_sap *sap,
545                                       const struct llc_addr *laddr,
546                                       const struct sock *sk)
547 {
548         struct llc_sock *llc = llc_sk(sk);
549
550         return sk->sk_type == SOCK_STREAM && sk->sk_state == TCP_LISTEN &&
551                 llc->laddr.lsap == laddr->lsap &&
552                 llc_mac_match(llc->laddr.mac, laddr->mac);
553 }
554
555 static struct sock *__llc_lookup_listener(struct llc_sap *sap,
556                                           struct llc_addr *laddr)
557 {
558         struct sock *rc;
559         struct hlist_nulls_node *node;
560         int slot = llc_sk_laddr_hashfn(sap, laddr);
561         struct hlist_nulls_head *laddr_hb = &sap->sk_laddr_hash[slot];
562
563         rcu_read_lock();
564 again:
565         sk_nulls_for_each_rcu(rc, node, laddr_hb) {
566                 if (llc_listener_match(sap, laddr, rc)) {
567                         /* Extra checks required by SLAB_DESTROY_BY_RCU */
568                         if (unlikely(!atomic_inc_not_zero(&rc->sk_refcnt)))
569                                 goto again;
570                         if (unlikely(llc_sk(rc)->sap != sap ||
571                                      !llc_listener_match(sap, laddr, rc))) {
572                                 sock_put(rc);
573                                 continue;
574                         }
575                         goto found;
576                 }
577         }
578         rc = NULL;
579         /*
580          * if the nulls value we got at the end of this lookup is
581          * not the expected one, we must restart lookup.
582          * We probably met an item that was moved to another chain.
583          */
584         if (unlikely(get_nulls_value(node) != slot))
585                 goto again;
586 found:
587         rcu_read_unlock();
588         return rc;
589 }
590
591 /**
592  *      llc_lookup_listener - Finds listener for local MAC + SAP
593  *      @sap: SAP
594  *      @laddr: address of local LLC (MAC + SAP)
595  *
596  *      Search connection list of the SAP and finds connection listening on
597  *      local mac, and local sap. Returns pointer for parent socket found,
598  *      %NULL otherwise.
599  *      Caller has to make sure local_bh is disabled.
600  */
601 static struct sock *llc_lookup_listener(struct llc_sap *sap,
602                                         struct llc_addr *laddr)
603 {
604         static struct llc_addr null_addr;
605         struct sock *rc = __llc_lookup_listener(sap, laddr);
606
607         if (!rc)
608                 rc = __llc_lookup_listener(sap, &null_addr);
609
610         return rc;
611 }
612
613 static struct sock *__llc_lookup(struct llc_sap *sap,
614                                  struct llc_addr *daddr,
615                                  struct llc_addr *laddr)
616 {
617         struct sock *sk = __llc_lookup_established(sap, daddr, laddr);
618
619         return sk ? : llc_lookup_listener(sap, laddr);
620 }
621
622 /**
623  *      llc_data_accept_state - designates if in this state data can be sent.
624  *      @state: state of connection.
625  *
626  *      Returns 0 if data can be sent, 1 otherwise.
627  */
628 u8 llc_data_accept_state(u8 state)
629 {
630         return state != LLC_CONN_STATE_NORMAL && state != LLC_CONN_STATE_BUSY &&
631                state != LLC_CONN_STATE_REJ;
632 }
633
634 /**
635  *      llc_find_next_offset - finds offset for next category of transitions
636  *      @state: state table.
637  *      @offset: start offset.
638  *
639  *      Finds offset of next category of transitions in transition table.
640  *      Returns the start index of next category.
641  */
642 static u16 __init llc_find_next_offset(struct llc_conn_state *state, u16 offset)
643 {
644         u16 cnt = 0;
645         struct llc_conn_state_trans **next_trans;
646
647         for (next_trans = state->transitions + offset;
648              (*next_trans)->ev; next_trans++)
649                 ++cnt;
650         return cnt;
651 }
652
653 /**
654  *      llc_build_offset_table - builds offset table of connection
655  *
656  *      Fills offset table of connection state transition table
657  *      (llc_offset_table).
658  */
659 void __init llc_build_offset_table(void)
660 {
661         struct llc_conn_state *curr_state;
662         int state, ev_type, next_offset;
663
664         for (state = 0; state < NBR_CONN_STATES; state++) {
665                 curr_state = &llc_conn_state_table[state];
666                 next_offset = 0;
667                 for (ev_type = 0; ev_type < NBR_CONN_EV; ev_type++) {
668                         llc_offset_table[state][ev_type] = next_offset;
669                         next_offset += llc_find_next_offset(curr_state,
670                                                             next_offset) + 1;
671                 }
672         }
673 }
674
675 /**
676  *      llc_find_offset - finds start offset of category of transitions
677  *      @state: state of connection
678  *      @ev_type: type of happened event
679  *
680  *      Finds start offset of desired category of transitions. Returns the
681  *      desired start offset.
682  */
683 static int llc_find_offset(int state, int ev_type)
684 {
685         int rc = 0;
686         /* at this stage, llc_offset_table[..][2] is not important. it is for
687          * init_pf_cycle and I don't know what is it.
688          */
689         switch (ev_type) {
690         case LLC_CONN_EV_TYPE_PRIM:
691                 rc = llc_offset_table[state][0]; break;
692         case LLC_CONN_EV_TYPE_PDU:
693                 rc = llc_offset_table[state][4]; break;
694         case LLC_CONN_EV_TYPE_SIMPLE:
695                 rc = llc_offset_table[state][1]; break;
696         case LLC_CONN_EV_TYPE_P_TMR:
697         case LLC_CONN_EV_TYPE_ACK_TMR:
698         case LLC_CONN_EV_TYPE_REJ_TMR:
699         case LLC_CONN_EV_TYPE_BUSY_TMR:
700                 rc = llc_offset_table[state][3]; break;
701         }
702         return rc;
703 }
704
705 /**
706  *      llc_sap_add_socket - adds a socket to a SAP
707  *      @sap: SAP
708  *      @sk: socket
709  *
710  *      This function adds a socket to the hash tables of a SAP.
711  */
712 void llc_sap_add_socket(struct llc_sap *sap, struct sock *sk)
713 {
714         struct llc_sock *llc = llc_sk(sk);
715         struct hlist_head *dev_hb = llc_sk_dev_hash(sap, llc->dev->ifindex);
716         struct hlist_nulls_head *laddr_hb = llc_sk_laddr_hash(sap, &llc->laddr);
717
718         llc_sap_hold(sap);
719         llc_sk(sk)->sap = sap;
720
721         spin_lock_bh(&sap->sk_lock);
722         sap->sk_count++;
723         sk_nulls_add_node_rcu(sk, laddr_hb);
724         hlist_add_head(&llc->dev_hash_node, dev_hb);
725         spin_unlock_bh(&sap->sk_lock);
726 }
727
728 /**
729  *      llc_sap_remove_socket - removes a socket from SAP
730  *      @sap: SAP
731  *      @sk: socket
732  *
733  *      This function removes a connection from the hash tables of a SAP if
734  *      the connection was in this list.
735  */
736 void llc_sap_remove_socket(struct llc_sap *sap, struct sock *sk)
737 {
738         struct llc_sock *llc = llc_sk(sk);
739
740         spin_lock_bh(&sap->sk_lock);
741         sk_nulls_del_node_init_rcu(sk);
742         hlist_del(&llc->dev_hash_node);
743         sap->sk_count--;
744         spin_unlock_bh(&sap->sk_lock);
745         llc_sap_put(sap);
746 }
747
748 /**
749  *      llc_conn_rcv - sends received pdus to the connection state machine
750  *      @sk: current connection structure.
751  *      @skb: received frame.
752  *
753  *      Sends received pdus to the connection state machine.
754  */
755 static int llc_conn_rcv(struct sock* sk, struct sk_buff *skb)
756 {
757         struct llc_conn_state_ev *ev = llc_conn_ev(skb);
758
759         ev->type   = LLC_CONN_EV_TYPE_PDU;
760         ev->reason = 0;
761         return llc_conn_state_process(sk, skb);
762 }
763
764 static struct sock *llc_create_incoming_sock(struct sock *sk,
765                                              struct net_device *dev,
766                                              struct llc_addr *saddr,
767                                              struct llc_addr *daddr)
768 {
769         struct sock *newsk = llc_sk_alloc(sock_net(sk), sk->sk_family, GFP_ATOMIC,
770                                           sk->sk_prot);
771         struct llc_sock *newllc, *llc = llc_sk(sk);
772
773         if (!newsk)
774                 goto out;
775         newllc = llc_sk(newsk);
776         memcpy(&newllc->laddr, daddr, sizeof(newllc->laddr));
777         memcpy(&newllc->daddr, saddr, sizeof(newllc->daddr));
778         newllc->dev = dev;
779         dev_hold(dev);
780         llc_sap_add_socket(llc->sap, newsk);
781         llc_sap_hold(llc->sap);
782 out:
783         return newsk;
784 }
785
786 void llc_conn_handler(struct llc_sap *sap, struct sk_buff *skb)
787 {
788         struct llc_addr saddr, daddr;
789         struct sock *sk;
790
791         llc_pdu_decode_sa(skb, saddr.mac);
792         llc_pdu_decode_ssap(skb, &saddr.lsap);
793         llc_pdu_decode_da(skb, daddr.mac);
794         llc_pdu_decode_dsap(skb, &daddr.lsap);
795
796         sk = __llc_lookup(sap, &saddr, &daddr);
797         if (!sk)
798                 goto drop;
799
800         bh_lock_sock(sk);
801         /*
802          * This has to be done here and not at the upper layer ->accept
803          * method because of the way the PROCOM state machine works:
804          * it needs to set several state variables (see, for instance,
805          * llc_adm_actions_2 in net/llc/llc_c_st.c) and send a packet to
806          * the originator of the new connection, and this state has to be
807          * in the newly created struct sock private area. -acme
808          */
809         if (unlikely(sk->sk_state == TCP_LISTEN)) {
810                 struct sock *newsk = llc_create_incoming_sock(sk, skb->dev,
811                                                               &saddr, &daddr);
812                 if (!newsk)
813                         goto drop_unlock;
814                 skb_set_owner_r(skb, newsk);
815         } else {
816                 /*
817                  * Can't be skb_set_owner_r, this will be done at the
818                  * llc_conn_state_process function, later on, when we will use
819                  * skb_queue_rcv_skb to send it to upper layers, this is
820                  * another trick required to cope with how the PROCOM state
821                  * machine works. -acme
822                  */
823                 skb->sk = sk;
824         }
825         if (!sock_owned_by_user(sk))
826                 llc_conn_rcv(sk, skb);
827         else {
828                 dprintk("%s: adding to backlog...\n", __func__);
829                 llc_set_backlog_type(skb, LLC_PACKET);
830                 if (sk_add_backlog_limited(sk, skb))
831                         goto drop_unlock;
832         }
833 out:
834         bh_unlock_sock(sk);
835         sock_put(sk);
836         return;
837 drop:
838         kfree_skb(skb);
839         return;
840 drop_unlock:
841         kfree_skb(skb);
842         goto out;
843 }
844
845 #undef LLC_REFCNT_DEBUG
846 #ifdef LLC_REFCNT_DEBUG
847 static atomic_t llc_sock_nr;
848 #endif
849
850 /**
851  *      llc_backlog_rcv - Processes rx frames and expired timers.
852  *      @sk: LLC sock (p8022 connection)
853  *      @skb: queued rx frame or event
854  *
855  *      This function processes frames that has received and timers that has
856  *      expired during sending an I pdu (refer to data_req_handler).  frames
857  *      queue by llc_rcv function (llc_mac.c) and timers queue by timer
858  *      callback functions(llc_c_ac.c).
859  */
860 static int llc_backlog_rcv(struct sock *sk, struct sk_buff *skb)
861 {
862         int rc = 0;
863         struct llc_sock *llc = llc_sk(sk);
864
865         if (likely(llc_backlog_type(skb) == LLC_PACKET)) {
866                 if (likely(llc->state > 1)) /* not closed */
867                         rc = llc_conn_rcv(sk, skb);
868                 else
869                         goto out_kfree_skb;
870         } else if (llc_backlog_type(skb) == LLC_EVENT) {
871                 /* timer expiration event */
872                 if (likely(llc->state > 1))  /* not closed */
873                         rc = llc_conn_state_process(sk, skb);
874                 else
875                         goto out_kfree_skb;
876         } else {
877                 printk(KERN_ERR "%s: invalid skb in backlog\n", __func__);
878                 goto out_kfree_skb;
879         }
880 out:
881         return rc;
882 out_kfree_skb:
883         kfree_skb(skb);
884         goto out;
885 }
886
887 /**
888  *     llc_sk_init - Initializes a socket with default llc values.
889  *     @sk: socket to initialize.
890  *
891  *     Initializes a socket with default llc values.
892  */
893 static void llc_sk_init(struct sock* sk)
894 {
895         struct llc_sock *llc = llc_sk(sk);
896
897         llc->state    = LLC_CONN_STATE_ADM;
898         llc->inc_cntr = llc->dec_cntr = 2;
899         llc->dec_step = llc->connect_step = 1;
900
901         setup_timer(&llc->ack_timer.timer, llc_conn_ack_tmr_cb,
902                         (unsigned long)sk);
903         llc->ack_timer.expire         = sysctl_llc2_ack_timeout;
904
905         setup_timer(&llc->pf_cycle_timer.timer, llc_conn_pf_cycle_tmr_cb,
906                         (unsigned long)sk);
907         llc->pf_cycle_timer.expire         = sysctl_llc2_p_timeout;
908
909         setup_timer(&llc->rej_sent_timer.timer, llc_conn_rej_tmr_cb,
910                         (unsigned long)sk);
911         llc->rej_sent_timer.expire         = sysctl_llc2_rej_timeout;
912
913         setup_timer(&llc->busy_state_timer.timer, llc_conn_busy_tmr_cb,
914                         (unsigned long)sk);
915         llc->busy_state_timer.expire         = sysctl_llc2_busy_timeout;
916
917         llc->n2 = 2;   /* max retransmit */
918         llc->k  = 2;   /* tx win size, will adjust dynam */
919         llc->rw = 128; /* rx win size (opt and equal to
920                         * tx_win of remote LLC) */
921         skb_queue_head_init(&llc->pdu_unack_q);
922         sk->sk_backlog_rcv = llc_backlog_rcv;
923 }
924
925 /**
926  *      llc_sk_alloc - Allocates LLC sock
927  *      @family: upper layer protocol family
928  *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
929  *
930  *      Allocates a LLC sock and initializes it. Returns the new LLC sock
931  *      or %NULL if there's no memory available for one
932  */
933 struct sock *llc_sk_alloc(struct net *net, int family, gfp_t priority, struct proto *prot)
934 {
935         struct sock *sk = sk_alloc(net, family, priority, prot);
936
937         if (!sk)
938                 goto out;
939         llc_sk_init(sk);
940         sock_init_data(NULL, sk);
941 #ifdef LLC_REFCNT_DEBUG
942         atomic_inc(&llc_sock_nr);
943         printk(KERN_DEBUG "LLC socket %p created in %s, now we have %d alive\n", sk,
944                 __func__, atomic_read(&llc_sock_nr));
945 #endif
946 out:
947         return sk;
948 }
949
950 /**
951  *      llc_sk_free - Frees a LLC socket
952  *      @sk - socket to free
953  *
954  *      Frees a LLC socket
955  */
956 void llc_sk_free(struct sock *sk)
957 {
958         struct llc_sock *llc = llc_sk(sk);
959
960         llc->state = LLC_CONN_OUT_OF_SVC;
961         /* Stop all (possibly) running timers */
962         llc_conn_ac_stop_all_timers(sk, NULL);
963 #ifdef DEBUG_LLC_CONN_ALLOC
964         printk(KERN_INFO "%s: unackq=%d, txq=%d\n", __func__,
965                 skb_queue_len(&llc->pdu_unack_q),
966                 skb_queue_len(&sk->sk_write_queue));
967 #endif
968         skb_queue_purge(&sk->sk_receive_queue);
969         skb_queue_purge(&sk->sk_write_queue);
970         skb_queue_purge(&llc->pdu_unack_q);
971 #ifdef LLC_REFCNT_DEBUG
972         if (atomic_read(&sk->sk_refcnt) != 1) {
973                 printk(KERN_DEBUG "Destruction of LLC sock %p delayed in %s, cnt=%d\n",
974                         sk, __func__, atomic_read(&sk->sk_refcnt));
975                 printk(KERN_DEBUG "%d LLC sockets are still alive\n",
976                         atomic_read(&llc_sock_nr));
977         } else {
978                 atomic_dec(&llc_sock_nr);
979                 printk(KERN_DEBUG "LLC socket %p released in %s, %d are still alive\n", sk,
980                         __func__, atomic_read(&llc_sock_nr));
981         }
982 #endif
983         sock_put(sk);
984 }
985
986 /**
987  *      llc_sk_reset - resets a connection
988  *      @sk: LLC socket to reset
989  *
990  *      Resets a connection to the out of service state. Stops its timers
991  *      and frees any frames in the queues of the connection.
992  */
993 void llc_sk_reset(struct sock *sk)
994 {
995         struct llc_sock *llc = llc_sk(sk);
996
997         llc_conn_ac_stop_all_timers(sk, NULL);
998         skb_queue_purge(&sk->sk_write_queue);
999         skb_queue_purge(&llc->pdu_unack_q);
1000         llc->remote_busy_flag   = 0;
1001         llc->cause_flag         = 0;
1002         llc->retry_count        = 0;
1003         llc_conn_set_p_flag(sk, 0);
1004         llc->f_flag             = 0;
1005         llc->s_flag             = 0;
1006         llc->ack_pf             = 0;
1007         llc->first_pdu_Ns       = 0;
1008         llc->ack_must_be_send   = 0;
1009         llc->dec_step           = 1;
1010         llc->inc_cntr           = 2;
1011         llc->dec_cntr           = 2;
1012         llc->X                  = 0;
1013         llc->failed_data_req    = 0 ;
1014         llc->last_nr            = 0;
1015 }