V4L/DVB (6601): V4L: videobuf-core locking fixes and comments
[linux-2.6] / net / tipc / subscr.c
1 /*
2  * net/tipc/subscr.c: TIPC subscription service
3  *
4  * Copyright (c) 2000-2006, Ericsson AB
5  * Copyright (c) 2005, 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 "dbg.h"
39 #include "subscr.h"
40 #include "name_table.h"
41 #include "ref.h"
42
43 /**
44  * struct subscriber - TIPC network topology subscriber
45  * @ref: object reference to subscriber object itself
46  * @lock: pointer to spinlock controlling access to subscriber object
47  * @subscriber_list: adjacent subscribers in top. server's list of subscribers
48  * @subscription_list: list of subscription objects for this subscriber
49  * @port_ref: object reference to port used to communicate with subscriber
50  * @swap: indicates if subscriber uses opposite endianness in its messages
51  */
52
53 struct subscriber {
54         u32 ref;
55         spinlock_t *lock;
56         struct list_head subscriber_list;
57         struct list_head subscription_list;
58         u32 port_ref;
59         int swap;
60 };
61
62 /**
63  * struct top_srv - TIPC network topology subscription service
64  * @user_ref: TIPC userid of subscription service
65  * @setup_port: reference to TIPC port that handles subscription requests
66  * @subscription_count: number of active subscriptions (not subscribers!)
67  * @subscriber_list: list of ports subscribing to service
68  * @lock: spinlock govering access to subscriber list
69  */
70
71 struct top_srv {
72         u32 user_ref;
73         u32 setup_port;
74         atomic_t subscription_count;
75         struct list_head subscriber_list;
76         spinlock_t lock;
77 };
78
79 static struct top_srv topsrv = { 0 };
80
81 /**
82  * htohl - convert value to endianness used by destination
83  * @in: value to convert
84  * @swap: non-zero if endianness must be reversed
85  *
86  * Returns converted value
87  */
88
89 static u32 htohl(u32 in, int swap)
90 {
91         char *c = (char *)∈
92
93         return swap ? ((c[3] << 3) + (c[2] << 2) + (c[1] << 1) + c[0]) : in;
94 }
95
96 /**
97  * subscr_send_event - send a message containing a tipc_event to the subscriber
98  */
99
100 static void subscr_send_event(struct subscription *sub,
101                               u32 found_lower,
102                               u32 found_upper,
103                               u32 event,
104                               u32 port_ref,
105                               u32 node)
106 {
107         struct iovec msg_sect;
108
109         msg_sect.iov_base = (void *)&sub->evt;
110         msg_sect.iov_len = sizeof(struct tipc_event);
111
112         sub->evt.event = htohl(event, sub->owner->swap);
113         sub->evt.found_lower = htohl(found_lower, sub->owner->swap);
114         sub->evt.found_upper = htohl(found_upper, sub->owner->swap);
115         sub->evt.port.ref = htohl(port_ref, sub->owner->swap);
116         sub->evt.port.node = htohl(node, sub->owner->swap);
117         tipc_send(sub->owner->port_ref, 1, &msg_sect);
118 }
119
120 /**
121  * tipc_subscr_overlap - test for subscription overlap with the given values
122  *
123  * Returns 1 if there is overlap, otherwise 0.
124  */
125
126 int tipc_subscr_overlap(struct subscription *sub,
127                         u32 found_lower,
128                         u32 found_upper)
129
130 {
131         if (found_lower < sub->seq.lower)
132                 found_lower = sub->seq.lower;
133         if (found_upper > sub->seq.upper)
134                 found_upper = sub->seq.upper;
135         if (found_lower > found_upper)
136                 return 0;
137         return 1;
138 }
139
140 /**
141  * tipc_subscr_report_overlap - issue event if there is subscription overlap
142  *
143  * Protected by nameseq.lock in name_table.c
144  */
145
146 void tipc_subscr_report_overlap(struct subscription *sub,
147                                 u32 found_lower,
148                                 u32 found_upper,
149                                 u32 event,
150                                 u32 port_ref,
151                                 u32 node,
152                                 int must)
153 {
154         dbg("Rep overlap %u:%u,%u<->%u,%u\n", sub->seq.type, sub->seq.lower,
155             sub->seq.upper, found_lower, found_upper);
156         if (!tipc_subscr_overlap(sub, found_lower, found_upper))
157                 return;
158         if (!must && !(sub->filter & TIPC_SUB_PORTS))
159                 return;
160         subscr_send_event(sub, found_lower, found_upper, event, port_ref, node);
161 }
162
163 /**
164  * subscr_timeout - subscription timeout has occurred
165  */
166
167 static void subscr_timeout(struct subscription *sub)
168 {
169         struct subscriber *subscriber;
170         u32 subscriber_ref;
171
172         /* Validate subscriber reference (in case subscriber is terminating) */
173
174         subscriber_ref = sub->owner->ref;
175         subscriber = (struct subscriber *)tipc_ref_lock(subscriber_ref);
176         if (subscriber == NULL)
177                 return;
178
179         /* Validate timeout (in case subscription is being cancelled) */
180
181         if (sub->timeout == TIPC_WAIT_FOREVER) {
182                 tipc_ref_unlock(subscriber_ref);
183                 return;
184         }
185
186         /* Unlink subscription from name table */
187
188         tipc_nametbl_unsubscribe(sub);
189
190         /* Notify subscriber of timeout, then unlink subscription */
191
192         subscr_send_event(sub,
193                           sub->evt.s.seq.lower,
194                           sub->evt.s.seq.upper,
195                           TIPC_SUBSCR_TIMEOUT,
196                           0,
197                           0);
198         list_del(&sub->subscription_list);
199
200         /* Now destroy subscription */
201
202         tipc_ref_unlock(subscriber_ref);
203         k_term_timer(&sub->timer);
204         kfree(sub);
205         atomic_dec(&topsrv.subscription_count);
206 }
207
208 /**
209  * subscr_del - delete a subscription within a subscription list
210  *
211  * Called with subscriber locked.
212  */
213
214 static void subscr_del(struct subscription *sub)
215 {
216         tipc_nametbl_unsubscribe(sub);
217         list_del(&sub->subscription_list);
218         kfree(sub);
219         atomic_dec(&topsrv.subscription_count);
220 }
221
222 /**
223  * subscr_terminate - terminate communication with a subscriber
224  *
225  * Called with subscriber locked.  Routine must temporarily release this lock
226  * to enable subscription timeout routine(s) to finish without deadlocking;
227  * the lock is then reclaimed to allow caller to release it upon return.
228  * (This should work even in the unlikely event some other thread creates
229  * a new object reference in the interim that uses this lock; this routine will
230  * simply wait for it to be released, then claim it.)
231  */
232
233 static void subscr_terminate(struct subscriber *subscriber)
234 {
235         struct subscription *sub;
236         struct subscription *sub_temp;
237
238         /* Invalidate subscriber reference */
239
240         tipc_ref_discard(subscriber->ref);
241         spin_unlock_bh(subscriber->lock);
242
243         /* Destroy any existing subscriptions for subscriber */
244
245         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
246                                  subscription_list) {
247                 if (sub->timeout != TIPC_WAIT_FOREVER) {
248                         k_cancel_timer(&sub->timer);
249                         k_term_timer(&sub->timer);
250                 }
251                 dbg("Term: Removing sub %u,%u,%u from subscriber %x list\n",
252                     sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
253                 subscr_del(sub);
254         }
255
256         /* Sever connection to subscriber */
257
258         tipc_shutdown(subscriber->port_ref);
259         tipc_deleteport(subscriber->port_ref);
260
261         /* Remove subscriber from topology server's subscriber list */
262
263         spin_lock_bh(&topsrv.lock);
264         list_del(&subscriber->subscriber_list);
265         spin_unlock_bh(&topsrv.lock);
266
267         /* Now destroy subscriber */
268
269         spin_lock_bh(subscriber->lock);
270         kfree(subscriber);
271 }
272
273 /**
274  * subscr_cancel - handle subscription cancellation request
275  *
276  * Called with subscriber locked.  Routine must temporarily release this lock
277  * to enable the subscription timeout routine to finish without deadlocking;
278  * the lock is then reclaimed to allow caller to release it upon return.
279  *
280  * Note that fields of 's' use subscriber's endianness!
281  */
282
283 static void subscr_cancel(struct tipc_subscr *s,
284                           struct subscriber *subscriber)
285 {
286         struct subscription *sub;
287         struct subscription *sub_temp;
288         int found = 0;
289
290         /* Find first matching subscription, exit if not found */
291
292         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
293                                  subscription_list) {
294                 if (!memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr))) {
295                         found = 1;
296                         break;
297                 }
298         }
299         if (!found)
300                 return;
301
302         /* Cancel subscription timer (if used), then delete subscription */
303
304         if (sub->timeout != TIPC_WAIT_FOREVER) {
305                 sub->timeout = TIPC_WAIT_FOREVER;
306                 spin_unlock_bh(subscriber->lock);
307                 k_cancel_timer(&sub->timer);
308                 k_term_timer(&sub->timer);
309                 spin_lock_bh(subscriber->lock);
310         }
311         dbg("Cancel: removing sub %u,%u,%u from subscriber %x list\n",
312             sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
313         subscr_del(sub);
314 }
315
316 /**
317  * subscr_subscribe - create subscription for subscriber
318  *
319  * Called with subscriber locked
320  */
321
322 static void subscr_subscribe(struct tipc_subscr *s,
323                              struct subscriber *subscriber)
324 {
325         struct subscription *sub;
326
327         /* Determine/update subscriber's endianness */
328
329         if (s->filter & (TIPC_SUB_PORTS | TIPC_SUB_SERVICE))
330                 subscriber->swap = 0;
331         else
332                 subscriber->swap = 1;
333
334         /* Detect & process a subscription cancellation request */
335
336         if (s->filter & htohl(TIPC_SUB_CANCEL, subscriber->swap)) {
337                 s->filter &= ~htohl(TIPC_SUB_CANCEL, subscriber->swap);
338                 subscr_cancel(s, subscriber);
339                 return;
340         }
341
342         /* Refuse subscription if global limit exceeded */
343
344         if (atomic_read(&topsrv.subscription_count) >= tipc_max_subscriptions) {
345                 warn("Subscription rejected, subscription limit reached (%u)\n",
346                      tipc_max_subscriptions);
347                 subscr_terminate(subscriber);
348                 return;
349         }
350
351         /* Allocate subscription object */
352
353         sub = kzalloc(sizeof(*sub), GFP_ATOMIC);
354         if (!sub) {
355                 warn("Subscription rejected, no memory\n");
356                 subscr_terminate(subscriber);
357                 return;
358         }
359
360         /* Initialize subscription object */
361
362         sub->seq.type = htohl(s->seq.type, subscriber->swap);
363         sub->seq.lower = htohl(s->seq.lower, subscriber->swap);
364         sub->seq.upper = htohl(s->seq.upper, subscriber->swap);
365         sub->timeout = htohl(s->timeout, subscriber->swap);
366         sub->filter = htohl(s->filter, subscriber->swap);
367         if ((!(sub->filter & TIPC_SUB_PORTS)
368              == !(sub->filter & TIPC_SUB_SERVICE))
369             || (sub->seq.lower > sub->seq.upper)) {
370                 warn("Subscription rejected, illegal request\n");
371                 kfree(sub);
372                 subscr_terminate(subscriber);
373                 return;
374         }
375         memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
376         INIT_LIST_HEAD(&sub->subscription_list);
377         INIT_LIST_HEAD(&sub->nameseq_list);
378         list_add(&sub->subscription_list, &subscriber->subscription_list);
379         atomic_inc(&topsrv.subscription_count);
380         if (sub->timeout != TIPC_WAIT_FOREVER) {
381                 k_init_timer(&sub->timer,
382                              (Handler)subscr_timeout, (unsigned long)sub);
383                 k_start_timer(&sub->timer, sub->timeout);
384         }
385         sub->owner = subscriber;
386         tipc_nametbl_subscribe(sub);
387 }
388
389 /**
390  * subscr_conn_shutdown_event - handle termination request from subscriber
391  */
392
393 static void subscr_conn_shutdown_event(void *usr_handle,
394                                        u32 portref,
395                                        struct sk_buff **buf,
396                                        unsigned char const *data,
397                                        unsigned int size,
398                                        int reason)
399 {
400         struct subscriber *subscriber;
401         spinlock_t *subscriber_lock;
402
403         subscriber = tipc_ref_lock((u32)(unsigned long)usr_handle);
404         if (subscriber == NULL)
405                 return;
406
407         subscriber_lock = subscriber->lock;
408         subscr_terminate(subscriber);
409         spin_unlock_bh(subscriber_lock);
410 }
411
412 /**
413  * subscr_conn_msg_event - handle new subscription request from subscriber
414  */
415
416 static void subscr_conn_msg_event(void *usr_handle,
417                                   u32 port_ref,
418                                   struct sk_buff **buf,
419                                   const unchar *data,
420                                   u32 size)
421 {
422         struct subscriber *subscriber;
423         spinlock_t *subscriber_lock;
424
425         subscriber = tipc_ref_lock((u32)(unsigned long)usr_handle);
426         if (subscriber == NULL)
427                 return;
428
429         subscriber_lock = subscriber->lock;
430         if (size != sizeof(struct tipc_subscr))
431                 subscr_terminate(subscriber);
432         else
433                 subscr_subscribe((struct tipc_subscr *)data, subscriber);
434
435         spin_unlock_bh(subscriber_lock);
436 }
437
438 /**
439  * subscr_named_msg_event - handle request to establish a new subscriber
440  */
441
442 static void subscr_named_msg_event(void *usr_handle,
443                                    u32 port_ref,
444                                    struct sk_buff **buf,
445                                    const unchar *data,
446                                    u32 size,
447                                    u32 importance,
448                                    struct tipc_portid const *orig,
449                                    struct tipc_name_seq const *dest)
450 {
451         struct subscriber *subscriber;
452         struct iovec msg_sect = {NULL, 0};
453         spinlock_t *subscriber_lock;
454
455         dbg("subscr_named_msg_event: orig = %x own = %x,\n",
456             orig->node, tipc_own_addr);
457         if (size && (size != sizeof(struct tipc_subscr))) {
458                 warn("Subscriber rejected, invalid subscription size\n");
459                 return;
460         }
461
462         /* Create subscriber object */
463
464         subscriber = kzalloc(sizeof(struct subscriber), GFP_ATOMIC);
465         if (subscriber == NULL) {
466                 warn("Subscriber rejected, no memory\n");
467                 return;
468         }
469         INIT_LIST_HEAD(&subscriber->subscription_list);
470         INIT_LIST_HEAD(&subscriber->subscriber_list);
471         subscriber->ref = tipc_ref_acquire(subscriber, &subscriber->lock);
472         if (subscriber->ref == 0) {
473                 warn("Subscriber rejected, reference table exhausted\n");
474                 kfree(subscriber);
475                 return;
476         }
477
478         /* Establish a connection to subscriber */
479
480         tipc_createport(topsrv.user_ref,
481                         (void *)(unsigned long)subscriber->ref,
482                         importance,
483                         NULL,
484                         NULL,
485                         subscr_conn_shutdown_event,
486                         NULL,
487                         NULL,
488                         subscr_conn_msg_event,
489                         NULL,
490                         &subscriber->port_ref);
491         if (subscriber->port_ref == 0) {
492                 warn("Subscriber rejected, unable to create port\n");
493                 tipc_ref_discard(subscriber->ref);
494                 kfree(subscriber);
495                 return;
496         }
497         tipc_connect2port(subscriber->port_ref, orig);
498
499
500         /* Add subscriber to topology server's subscriber list */
501
502         tipc_ref_lock(subscriber->ref);
503         spin_lock_bh(&topsrv.lock);
504         list_add(&subscriber->subscriber_list, &topsrv.subscriber_list);
505         spin_unlock_bh(&topsrv.lock);
506
507         /*
508          * Subscribe now if message contains a subscription,
509          * otherwise send an empty response to complete connection handshaking
510          */
511
512         subscriber_lock = subscriber->lock;
513         if (size)
514                 subscr_subscribe((struct tipc_subscr *)data, subscriber);
515         else
516                 tipc_send(subscriber->port_ref, 1, &msg_sect);
517
518         spin_unlock_bh(subscriber_lock);
519 }
520
521 int tipc_subscr_start(void)
522 {
523         struct tipc_name_seq seq = {TIPC_TOP_SRV, TIPC_TOP_SRV, TIPC_TOP_SRV};
524         int res = -1;
525
526         memset(&topsrv, 0, sizeof (topsrv));
527         spin_lock_init(&topsrv.lock);
528         INIT_LIST_HEAD(&topsrv.subscriber_list);
529
530         spin_lock_bh(&topsrv.lock);
531         res = tipc_attach(&topsrv.user_ref, NULL, NULL);
532         if (res) {
533                 spin_unlock_bh(&topsrv.lock);
534                 return res;
535         }
536
537         res = tipc_createport(topsrv.user_ref,
538                               NULL,
539                               TIPC_CRITICAL_IMPORTANCE,
540                               NULL,
541                               NULL,
542                               NULL,
543                               NULL,
544                               subscr_named_msg_event,
545                               NULL,
546                               NULL,
547                               &topsrv.setup_port);
548         if (res)
549                 goto failed;
550
551         res = tipc_nametbl_publish_rsv(topsrv.setup_port, TIPC_NODE_SCOPE, &seq);
552         if (res)
553                 goto failed;
554
555         spin_unlock_bh(&topsrv.lock);
556         return 0;
557
558 failed:
559         err("Failed to create subscription service\n");
560         tipc_detach(topsrv.user_ref);
561         topsrv.user_ref = 0;
562         spin_unlock_bh(&topsrv.lock);
563         return res;
564 }
565
566 void tipc_subscr_stop(void)
567 {
568         struct subscriber *subscriber;
569         struct subscriber *subscriber_temp;
570         spinlock_t *subscriber_lock;
571
572         if (topsrv.user_ref) {
573                 tipc_deleteport(topsrv.setup_port);
574                 list_for_each_entry_safe(subscriber, subscriber_temp,
575                                          &topsrv.subscriber_list,
576                                          subscriber_list) {
577                         tipc_ref_lock(subscriber->ref);
578                         subscriber_lock = subscriber->lock;
579                         subscr_terminate(subscriber);
580                         spin_unlock_bh(subscriber_lock);
581                 }
582                 tipc_detach(topsrv.user_ref);
583                 topsrv.user_ref = 0;
584         }
585 }
586
587
588 int tipc_ispublished(struct tipc_name const *name)
589 {
590         u32 domain = 0;
591
592         return(tipc_nametbl_translate(name->type, name->instance,&domain) != 0);
593 }
594