Bluetooth: Fix a compile warning in RFCOMM
[linux-2.6.git] / net / tipc / subscr.c
1 /*
2  * net/tipc/subscr.c: TIPC network topology service
3  *
4  * Copyright (c) 2000-2006, Ericsson AB
5  * Copyright (c) 2005-2007, 2010-2011, Wind River Systems
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions are met:
10  *
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the names of the copyright holders nor the names of its
17  *    contributors may be used to endorse or promote products derived from
18  *    this software without specific prior written permission.
19  *
20  * Alternatively, this software may be distributed under the terms of the
21  * GNU General Public License ("GPL") version 2 as published by the Free
22  * Software Foundation.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
25  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
28  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
29  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
30  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
31  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
32  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
33  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
34  * POSSIBILITY OF SUCH DAMAGE.
35  */
36
37 #include "core.h"
38 #include "name_table.h"
39 #include "port.h"
40 #include "subscr.h"
41
42 /**
43  * struct subscriber - TIPC network topology subscriber
44  * @port_ref: object reference to server port connecting to subscriber
45  * @lock: pointer to spinlock controlling access to subscriber's server port
46  * @subscriber_list: adjacent subscribers in top. server's list of subscribers
47  * @subscription_list: list of subscription objects for this subscriber
48  */
49
50 struct subscriber {
51         u32 port_ref;
52         spinlock_t *lock;
53         struct list_head subscriber_list;
54         struct list_head subscription_list;
55 };
56
57 /**
58  * struct top_srv - TIPC network topology subscription service
59  * @user_ref: TIPC userid of subscription service
60  * @setup_port: reference to TIPC port that handles subscription requests
61  * @subscription_count: number of active subscriptions (not subscribers!)
62  * @subscriber_list: list of ports subscribing to service
63  * @lock: spinlock govering access to subscriber list
64  */
65
66 struct top_srv {
67         u32 setup_port;
68         atomic_t subscription_count;
69         struct list_head subscriber_list;
70         spinlock_t lock;
71 };
72
73 static struct top_srv topsrv;
74
75 /**
76  * htohl - convert value to endianness used by destination
77  * @in: value to convert
78  * @swap: non-zero if endianness must be reversed
79  *
80  * Returns converted value
81  */
82
83 static u32 htohl(u32 in, int swap)
84 {
85         return swap ? swab32(in) : in;
86 }
87
88 /**
89  * subscr_send_event - send a message containing a tipc_event to the subscriber
90  *
91  * Note: Must not hold subscriber's server port lock, since tipc_send() will
92  *       try to take the lock if the message is rejected and returned!
93  */
94
95 static void subscr_send_event(struct subscription *sub,
96                               u32 found_lower,
97                               u32 found_upper,
98                               u32 event,
99                               u32 port_ref,
100                               u32 node)
101 {
102         struct iovec msg_sect;
103
104         msg_sect.iov_base = (void *)&sub->evt;
105         msg_sect.iov_len = sizeof(struct tipc_event);
106
107         sub->evt.event = htohl(event, sub->swap);
108         sub->evt.found_lower = htohl(found_lower, sub->swap);
109         sub->evt.found_upper = htohl(found_upper, sub->swap);
110         sub->evt.port.ref = htohl(port_ref, sub->swap);
111         sub->evt.port.node = htohl(node, sub->swap);
112         tipc_send(sub->server_ref, 1, &msg_sect, msg_sect.iov_len);
113 }
114
115 /**
116  * tipc_subscr_overlap - test for subscription overlap with the given values
117  *
118  * Returns 1 if there is overlap, otherwise 0.
119  */
120
121 int tipc_subscr_overlap(struct subscription *sub,
122                         u32 found_lower,
123                         u32 found_upper)
124
125 {
126         if (found_lower < sub->seq.lower)
127                 found_lower = sub->seq.lower;
128         if (found_upper > sub->seq.upper)
129                 found_upper = sub->seq.upper;
130         if (found_lower > found_upper)
131                 return 0;
132         return 1;
133 }
134
135 /**
136  * tipc_subscr_report_overlap - issue event if there is subscription overlap
137  *
138  * Protected by nameseq.lock in name_table.c
139  */
140
141 void tipc_subscr_report_overlap(struct subscription *sub,
142                                 u32 found_lower,
143                                 u32 found_upper,
144                                 u32 event,
145                                 u32 port_ref,
146                                 u32 node,
147                                 int must)
148 {
149         if (!tipc_subscr_overlap(sub, found_lower, found_upper))
150                 return;
151         if (!must && !(sub->filter & TIPC_SUB_PORTS))
152                 return;
153
154         subscr_send_event(sub, found_lower, found_upper, event, port_ref, node);
155 }
156
157 /**
158  * subscr_timeout - subscription timeout has occurred
159  */
160
161 static void subscr_timeout(struct subscription *sub)
162 {
163         struct tipc_port *server_port;
164
165         /* Validate server port reference (in case subscriber is terminating) */
166
167         server_port = tipc_port_lock(sub->server_ref);
168         if (server_port == NULL)
169                 return;
170
171         /* Validate timeout (in case subscription is being cancelled) */
172
173         if (sub->timeout == TIPC_WAIT_FOREVER) {
174                 tipc_port_unlock(server_port);
175                 return;
176         }
177
178         /* Unlink subscription from name table */
179
180         tipc_nametbl_unsubscribe(sub);
181
182         /* Unlink subscription from subscriber */
183
184         list_del(&sub->subscription_list);
185
186         /* Release subscriber's server port */
187
188         tipc_port_unlock(server_port);
189
190         /* Notify subscriber of timeout */
191
192         subscr_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper,
193                           TIPC_SUBSCR_TIMEOUT, 0, 0);
194
195         /* Now destroy subscription */
196
197         k_term_timer(&sub->timer);
198         kfree(sub);
199         atomic_dec(&topsrv.subscription_count);
200 }
201
202 /**
203  * subscr_del - delete a subscription within a subscription list
204  *
205  * Called with subscriber port locked.
206  */
207
208 static void subscr_del(struct subscription *sub)
209 {
210         tipc_nametbl_unsubscribe(sub);
211         list_del(&sub->subscription_list);
212         kfree(sub);
213         atomic_dec(&topsrv.subscription_count);
214 }
215
216 /**
217  * subscr_terminate - terminate communication with a subscriber
218  *
219  * Called with subscriber port locked.  Routine must temporarily release lock
220  * to enable subscription timeout routine(s) to finish without deadlocking;
221  * the lock is then reclaimed to allow caller to release it upon return.
222  * (This should work even in the unlikely event some other thread creates
223  * a new object reference in the interim that uses this lock; this routine will
224  * simply wait for it to be released, then claim it.)
225  */
226
227 static void subscr_terminate(struct subscriber *subscriber)
228 {
229         u32 port_ref;
230         struct subscription *sub;
231         struct subscription *sub_temp;
232
233         /* Invalidate subscriber reference */
234
235         port_ref = subscriber->port_ref;
236         subscriber->port_ref = 0;
237         spin_unlock_bh(subscriber->lock);
238
239         /* Sever connection to subscriber */
240
241         tipc_shutdown(port_ref);
242         tipc_deleteport(port_ref);
243
244         /* Destroy any existing subscriptions for subscriber */
245
246         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
247                                  subscription_list) {
248                 if (sub->timeout != TIPC_WAIT_FOREVER) {
249                         k_cancel_timer(&sub->timer);
250                         k_term_timer(&sub->timer);
251                 }
252                 subscr_del(sub);
253         }
254
255         /* Remove subscriber from topology server's subscriber list */
256
257         spin_lock_bh(&topsrv.lock);
258         list_del(&subscriber->subscriber_list);
259         spin_unlock_bh(&topsrv.lock);
260
261         /* Reclaim subscriber lock */
262
263         spin_lock_bh(subscriber->lock);
264
265         /* Now destroy subscriber */
266
267         kfree(subscriber);
268 }
269
270 /**
271  * subscr_cancel - handle subscription cancellation request
272  *
273  * Called with subscriber port locked.  Routine must temporarily release lock
274  * to enable the subscription timeout routine to finish without deadlocking;
275  * the lock is then reclaimed to allow caller to release it upon return.
276  *
277  * Note that fields of 's' use subscriber's endianness!
278  */
279
280 static void subscr_cancel(struct tipc_subscr *s,
281                           struct subscriber *subscriber)
282 {
283         struct subscription *sub;
284         struct subscription *sub_temp;
285         int found = 0;
286
287         /* Find first matching subscription, exit if not found */
288
289         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
290                                  subscription_list) {
291                 if (!memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr))) {
292                         found = 1;
293                         break;
294                 }
295         }
296         if (!found)
297                 return;
298
299         /* Cancel subscription timer (if used), then delete subscription */
300
301         if (sub->timeout != TIPC_WAIT_FOREVER) {
302                 sub->timeout = TIPC_WAIT_FOREVER;
303                 spin_unlock_bh(subscriber->lock);
304                 k_cancel_timer(&sub->timer);
305                 k_term_timer(&sub->timer);
306                 spin_lock_bh(subscriber->lock);
307         }
308         subscr_del(sub);
309 }
310
311 /**
312  * subscr_subscribe - create subscription for subscriber
313  *
314  * Called with subscriber port locked.
315  */
316
317 static struct subscription *subscr_subscribe(struct tipc_subscr *s,
318                                              struct subscriber *subscriber)
319 {
320         struct subscription *sub;
321         int swap;
322
323         /* Determine subscriber's endianness */
324
325         swap = !(s->filter & (TIPC_SUB_PORTS | TIPC_SUB_SERVICE));
326
327         /* Detect & process a subscription cancellation request */
328
329         if (s->filter & htohl(TIPC_SUB_CANCEL, swap)) {
330                 s->filter &= ~htohl(TIPC_SUB_CANCEL, swap);
331                 subscr_cancel(s, subscriber);
332                 return NULL;
333         }
334
335         /* Refuse subscription if global limit exceeded */
336
337         if (atomic_read(&topsrv.subscription_count) >= tipc_max_subscriptions) {
338                 warn("Subscription rejected, subscription limit reached (%u)\n",
339                      tipc_max_subscriptions);
340                 subscr_terminate(subscriber);
341                 return NULL;
342         }
343
344         /* Allocate subscription object */
345
346         sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
347         if (!sub) {
348                 warn("Subscription rejected, no memory\n");
349                 subscr_terminate(subscriber);
350                 return NULL;
351         }
352
353         /* Initialize subscription object */
354
355         sub->seq.type = htohl(s->seq.type, swap);
356         sub->seq.lower = htohl(s->seq.lower, swap);
357         sub->seq.upper = htohl(s->seq.upper, swap);
358         sub->timeout = htohl(s->timeout, swap);
359         sub->filter = htohl(s->filter, swap);
360         if ((!(sub->filter & TIPC_SUB_PORTS) ==
361              !(sub->filter & TIPC_SUB_SERVICE)) ||
362             (sub->seq.lower > sub->seq.upper)) {
363                 warn("Subscription rejected, illegal request\n");
364                 kfree(sub);
365                 subscr_terminate(subscriber);
366                 return NULL;
367         }
368         INIT_LIST_HEAD(&sub->nameseq_list);
369         list_add(&sub->subscription_list, &subscriber->subscription_list);
370         sub->server_ref = subscriber->port_ref;
371         sub->swap = swap;
372         memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
373         atomic_inc(&topsrv.subscription_count);
374         if (sub->timeout != TIPC_WAIT_FOREVER) {
375                 k_init_timer(&sub->timer,
376                              (Handler)subscr_timeout, (unsigned long)sub);
377                 k_start_timer(&sub->timer, sub->timeout);
378         }
379
380         return sub;
381 }
382
383 /**
384  * subscr_conn_shutdown_event - handle termination request from subscriber
385  *
386  * Called with subscriber's server port unlocked.
387  */
388
389 static void subscr_conn_shutdown_event(void *usr_handle,
390                                        u32 port_ref,
391                                        struct sk_buff **buf,
392                                        unsigned char const *data,
393                                        unsigned int size,
394                                        int reason)
395 {
396         struct subscriber *subscriber = usr_handle;
397         spinlock_t *subscriber_lock;
398
399         if (tipc_port_lock(port_ref) == NULL)
400                 return;
401
402         subscriber_lock = subscriber->lock;
403         subscr_terminate(subscriber);
404         spin_unlock_bh(subscriber_lock);
405 }
406
407 /**
408  * subscr_conn_msg_event - handle new subscription request from subscriber
409  *
410  * Called with subscriber's server port unlocked.
411  */
412
413 static void subscr_conn_msg_event(void *usr_handle,
414                                   u32 port_ref,
415                                   struct sk_buff **buf,
416                                   const unchar *data,
417                                   u32 size)
418 {
419         struct subscriber *subscriber = usr_handle;
420         spinlock_t *subscriber_lock;
421         struct subscription *sub;
422
423         /*
424          * Lock subscriber's server port (& make a local copy of lock pointer,
425          * in case subscriber is deleted while processing subscription request)
426          */
427
428         if (tipc_port_lock(port_ref) == NULL)
429                 return;
430
431         subscriber_lock = subscriber->lock;
432
433         if (size != sizeof(struct tipc_subscr)) {
434                 subscr_terminate(subscriber);
435                 spin_unlock_bh(subscriber_lock);
436         } else {
437                 sub = subscr_subscribe((struct tipc_subscr *)data, subscriber);
438                 spin_unlock_bh(subscriber_lock);
439                 if (sub != NULL) {
440
441                         /*
442                          * We must release the server port lock before adding a
443                          * subscription to the name table since TIPC needs to be
444                          * able to (re)acquire the port lock if an event message
445                          * issued by the subscription process is rejected and
446                          * returned.  The subscription cannot be deleted while
447                          * it is being added to the name table because:
448                          * a) the single-threading of the native API port code
449                          *    ensures the subscription cannot be cancelled and
450                          *    the subscriber connection cannot be broken, and
451                          * b) the name table lock ensures the subscription
452                          *    timeout code cannot delete the subscription,
453                          * so the subscription object is still protected.
454                          */
455
456                         tipc_nametbl_subscribe(sub);
457                 }
458         }
459 }
460
461 /**
462  * subscr_named_msg_event - handle request to establish a new subscriber
463  */
464
465 static void subscr_named_msg_event(void *usr_handle,
466                                    u32 port_ref,
467                                    struct sk_buff **buf,
468                                    const unchar *data,
469                                    u32 size,
470                                    u32 importance,
471                                    struct tipc_portid const *orig,
472                                    struct tipc_name_seq const *dest)
473 {
474         struct subscriber *subscriber;
475         u32 server_port_ref;
476
477         /* Create subscriber object */
478
479         subscriber = kzalloc(sizeof(struct subscriber), GFP_ATOMIC);
480         if (subscriber == NULL) {
481                 warn("Subscriber rejected, no memory\n");
482                 return;
483         }
484         INIT_LIST_HEAD(&subscriber->subscription_list);
485         INIT_LIST_HEAD(&subscriber->subscriber_list);
486
487         /* Create server port & establish connection to subscriber */
488
489         tipc_createport(subscriber,
490                         importance,
491                         NULL,
492                         NULL,
493                         subscr_conn_shutdown_event,
494                         NULL,
495                         NULL,
496                         subscr_conn_msg_event,
497                         NULL,
498                         &subscriber->port_ref);
499         if (subscriber->port_ref == 0) {
500                 warn("Subscriber rejected, unable to create port\n");
501                 kfree(subscriber);
502                 return;
503         }
504         tipc_connect2port(subscriber->port_ref, orig);
505
506         /* Lock server port (& save lock address for future use) */
507
508         subscriber->lock = tipc_port_lock(subscriber->port_ref)->lock;
509
510         /* Add subscriber to topology server's subscriber list */
511
512         spin_lock_bh(&topsrv.lock);
513         list_add(&subscriber->subscriber_list, &topsrv.subscriber_list);
514         spin_unlock_bh(&topsrv.lock);
515
516         /* Unlock server port */
517
518         server_port_ref = subscriber->port_ref;
519         spin_unlock_bh(subscriber->lock);
520
521         /* Send an ACK- to complete connection handshaking */
522
523         tipc_send(server_port_ref, 0, NULL, 0);
524
525         /* Handle optional subscription request */
526
527         if (size != 0) {
528                 subscr_conn_msg_event(subscriber, server_port_ref,
529                                       buf, data, size);
530         }
531 }
532
533 int tipc_subscr_start(void)
534 {
535         struct tipc_name_seq seq = {TIPC_TOP_SRV, TIPC_TOP_SRV, TIPC_TOP_SRV};
536         int res;
537
538         memset(&topsrv, 0, sizeof(topsrv));
539         spin_lock_init(&topsrv.lock);
540         INIT_LIST_HEAD(&topsrv.subscriber_list);
541
542         res = tipc_createport(NULL,
543                               TIPC_CRITICAL_IMPORTANCE,
544                               NULL,
545                               NULL,
546                               NULL,
547                               NULL,
548                               subscr_named_msg_event,
549                               NULL,
550                               NULL,
551                               &topsrv.setup_port);
552         if (res)
553                 goto failed;
554
555         res = tipc_nametbl_publish_rsv(topsrv.setup_port, TIPC_NODE_SCOPE, &seq);
556         if (res) {
557                 tipc_deleteport(topsrv.setup_port);
558                 topsrv.setup_port = 0;
559                 goto failed;
560         }
561
562         return 0;
563
564 failed:
565         err("Failed to create subscription service\n");
566         return res;
567 }
568
569 void tipc_subscr_stop(void)
570 {
571         struct subscriber *subscriber;
572         struct subscriber *subscriber_temp;
573         spinlock_t *subscriber_lock;
574
575         if (topsrv.setup_port) {
576                 tipc_deleteport(topsrv.setup_port);
577                 topsrv.setup_port = 0;
578
579                 list_for_each_entry_safe(subscriber, subscriber_temp,
580                                          &topsrv.subscriber_list,
581                                          subscriber_list) {
582                         subscriber_lock = subscriber->lock;
583                         spin_lock_bh(subscriber_lock);
584                         subscr_terminate(subscriber);
585                         spin_unlock_bh(subscriber_lock);
586                 }
587         }
588 }