net: return operator cleanup
[linux-3.10.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, 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 "name_table.h"
40 #include "port.h"
41 #include "ref.h"
42 #include "subscr.h"
43
44 /**
45  * struct subscriber - TIPC network topology subscriber
46  * @port_ref: object reference to server port connecting to subscriber
47  * @lock: pointer to spinlock controlling access to subscriber's server port
48  * @subscriber_list: adjacent subscribers in top. server's list of subscribers
49  * @subscription_list: list of subscription objects for this subscriber
50  */
51
52 struct subscriber {
53         u32 port_ref;
54         spinlock_t *lock;
55         struct list_head subscriber_list;
56         struct list_head subscription_list;
57 };
58
59 /**
60  * struct top_srv - TIPC network topology subscription service
61  * @user_ref: TIPC userid of subscription service
62  * @setup_port: reference to TIPC port that handles subscription requests
63  * @subscription_count: number of active subscriptions (not subscribers!)
64  * @subscriber_list: list of ports subscribing to service
65  * @lock: spinlock govering access to subscriber list
66  */
67
68 struct top_srv {
69         u32 user_ref;
70         u32 setup_port;
71         atomic_t subscription_count;
72         struct list_head subscriber_list;
73         spinlock_t lock;
74 };
75
76 static struct top_srv topsrv = { 0 };
77
78 /**
79  * subscr_send_event - send a message containing a tipc_event to the subscriber
80  *
81  * Note: Must not hold subscriber's server port lock, since tipc_send() will
82  *       try to take the lock if the message is rejected and returned!
83  */
84
85 static void subscr_send_event(struct subscription *sub,
86                               u32 found_lower,
87                               u32 found_upper,
88                               u32 event,
89                               u32 port_ref,
90                               u32 node)
91 {
92         struct iovec msg_sect;
93
94         msg_sect.iov_base = (void *)&sub->evt;
95         msg_sect.iov_len = sizeof(struct tipc_event);
96
97         sub->evt.event = htonl(event);
98         sub->evt.found_lower = htonl(found_lower);
99         sub->evt.found_upper = htonl(found_upper);
100         sub->evt.port.ref = htonl(port_ref);
101         sub->evt.port.node = htonl(node);
102         tipc_send(sub->server_ref, 1, &msg_sect);
103 }
104
105 /**
106  * tipc_subscr_overlap - test for subscription overlap with the given values
107  *
108  * Returns 1 if there is overlap, otherwise 0.
109  */
110
111 int tipc_subscr_overlap(struct subscription *sub,
112                         u32 found_lower,
113                         u32 found_upper)
114
115 {
116         if (found_lower < sub->seq.lower)
117                 found_lower = sub->seq.lower;
118         if (found_upper > sub->seq.upper)
119                 found_upper = sub->seq.upper;
120         if (found_lower > found_upper)
121                 return 0;
122         return 1;
123 }
124
125 /**
126  * tipc_subscr_report_overlap - issue event if there is subscription overlap
127  *
128  * Protected by nameseq.lock in name_table.c
129  */
130
131 void tipc_subscr_report_overlap(struct subscription *sub,
132                                 u32 found_lower,
133                                 u32 found_upper,
134                                 u32 event,
135                                 u32 port_ref,
136                                 u32 node,
137                                 int must)
138 {
139         if (!tipc_subscr_overlap(sub, found_lower, found_upper))
140                 return;
141         if (!must && !(sub->filter & TIPC_SUB_PORTS))
142                 return;
143
144         sub->event_cb(sub, found_lower, found_upper, event, port_ref, node);
145 }
146
147 /**
148  * subscr_timeout - subscription timeout has occurred
149  */
150
151 static void subscr_timeout(struct subscription *sub)
152 {
153         struct port *server_port;
154
155         /* Validate server port reference (in case subscriber is terminating) */
156
157         server_port = tipc_port_lock(sub->server_ref);
158         if (server_port == NULL)
159                 return;
160
161         /* Validate timeout (in case subscription is being cancelled) */
162
163         if (sub->timeout == TIPC_WAIT_FOREVER) {
164                 tipc_port_unlock(server_port);
165                 return;
166         }
167
168         /* Unlink subscription from name table */
169
170         tipc_nametbl_unsubscribe(sub);
171
172         /* Unlink subscription from subscriber */
173
174         list_del(&sub->subscription_list);
175
176         /* Release subscriber's server port */
177
178         tipc_port_unlock(server_port);
179
180         /* Notify subscriber of timeout */
181
182         subscr_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper,
183                           TIPC_SUBSCR_TIMEOUT, 0, 0);
184
185         /* Now destroy subscription */
186
187         k_term_timer(&sub->timer);
188         kfree(sub);
189         atomic_dec(&topsrv.subscription_count);
190 }
191
192 /**
193  * subscr_del - delete a subscription within a subscription list
194  *
195  * Called with subscriber port locked.
196  */
197
198 static void subscr_del(struct subscription *sub)
199 {
200         tipc_nametbl_unsubscribe(sub);
201         list_del(&sub->subscription_list);
202         kfree(sub);
203         atomic_dec(&topsrv.subscription_count);
204 }
205
206 /**
207  * subscr_terminate - terminate communication with a subscriber
208  *
209  * Called with subscriber port locked.  Routine must temporarily release lock
210  * to enable subscription timeout routine(s) to finish without deadlocking;
211  * the lock is then reclaimed to allow caller to release it upon return.
212  * (This should work even in the unlikely event some other thread creates
213  * a new object reference in the interim that uses this lock; this routine will
214  * simply wait for it to be released, then claim it.)
215  */
216
217 static void subscr_terminate(struct subscriber *subscriber)
218 {
219         u32 port_ref;
220         struct subscription *sub;
221         struct subscription *sub_temp;
222
223         /* Invalidate subscriber reference */
224
225         port_ref = subscriber->port_ref;
226         subscriber->port_ref = 0;
227         spin_unlock_bh(subscriber->lock);
228
229         /* Sever connection to subscriber */
230
231         tipc_shutdown(port_ref);
232         tipc_deleteport(port_ref);
233
234         /* Destroy any existing subscriptions for subscriber */
235
236         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
237                                  subscription_list) {
238                 if (sub->timeout != TIPC_WAIT_FOREVER) {
239                         k_cancel_timer(&sub->timer);
240                         k_term_timer(&sub->timer);
241                 }
242                 dbg("Term: Removing sub %u,%u,%u from subscriber %x list\n",
243                     sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
244                 subscr_del(sub);
245         }
246
247         /* Remove subscriber from topology server's subscriber list */
248
249         spin_lock_bh(&topsrv.lock);
250         list_del(&subscriber->subscriber_list);
251         spin_unlock_bh(&topsrv.lock);
252
253         /* Reclaim subscriber lock */
254
255         spin_lock_bh(subscriber->lock);
256
257         /* Now destroy subscriber */
258
259         kfree(subscriber);
260 }
261
262 /**
263  * subscr_cancel - handle subscription cancellation request
264  *
265  * Called with subscriber port locked.  Routine must temporarily release lock
266  * to enable the subscription timeout routine to finish without deadlocking;
267  * the lock is then reclaimed to allow caller to release it upon return.
268  *
269  * Note that fields of 's' use subscriber's endianness!
270  */
271
272 static void subscr_cancel(struct tipc_subscr *s,
273                           struct subscriber *subscriber)
274 {
275         struct subscription *sub;
276         struct subscription *sub_temp;
277         __u32 type, lower, upper, timeout, filter;
278         int found = 0;
279
280         /* Find first matching subscription, exit if not found */
281
282         type = ntohl(s->seq.type);
283         lower = ntohl(s->seq.lower);
284         upper = ntohl(s->seq.upper);
285         timeout = ntohl(s->timeout);
286         filter = ntohl(s->filter) & ~TIPC_SUB_CANCEL;
287
288         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
289                                  subscription_list) {
290                         if ((type == sub->seq.type) &&
291                             (lower == sub->seq.lower) &&
292                             (upper == sub->seq.upper) &&
293                             (timeout == sub->timeout) &&
294                             (filter == sub->filter) &&
295                              !memcmp(s->usr_handle,sub->evt.s.usr_handle,
296                                      sizeof(s->usr_handle)) ){
297                                 found = 1;
298                                 break;
299                         }
300         }
301         if (!found)
302                 return;
303
304         /* Cancel subscription timer (if used), then delete subscription */
305
306         if (sub->timeout != TIPC_WAIT_FOREVER) {
307                 sub->timeout = TIPC_WAIT_FOREVER;
308                 spin_unlock_bh(subscriber->lock);
309                 k_cancel_timer(&sub->timer);
310                 k_term_timer(&sub->timer);
311                 spin_lock_bh(subscriber->lock);
312         }
313         dbg("Cancel: removing sub %u,%u,%u from subscriber %p list\n",
314             sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
315         subscr_del(sub);
316 }
317
318 /**
319  * subscr_subscribe - create subscription for subscriber
320  *
321  * Called with subscriber port locked.
322  */
323
324 static struct subscription *subscr_subscribe(struct tipc_subscr *s,
325                                              struct subscriber *subscriber)
326 {
327         struct subscription *sub;
328
329         /* Detect & process a subscription cancellation request */
330
331         if (ntohl(s->filter) & TIPC_SUB_CANCEL) {
332                 subscr_cancel(s, subscriber);
333                 return NULL;
334         }
335
336         /* Refuse subscription if global limit exceeded */
337
338         if (atomic_read(&topsrv.subscription_count) >= tipc_max_subscriptions) {
339                 warn("Subscription rejected, subscription limit reached (%u)\n",
340                      tipc_max_subscriptions);
341                 subscr_terminate(subscriber);
342                 return NULL;
343         }
344
345         /* Allocate subscription object */
346
347         sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
348         if (!sub) {
349                 warn("Subscription rejected, no memory\n");
350                 subscr_terminate(subscriber);
351                 return NULL;
352         }
353
354         /* Initialize subscription object */
355
356         sub->seq.type = ntohl(s->seq.type);
357         sub->seq.lower = ntohl(s->seq.lower);
358         sub->seq.upper = ntohl(s->seq.upper);
359         sub->timeout = ntohl(s->timeout);
360         sub->filter = ntohl(s->filter);
361         if ((sub->filter && (sub->filter != TIPC_SUB_PORTS)) ||
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         sub->event_cb = subscr_send_event;
369         INIT_LIST_HEAD(&sub->nameseq_list);
370         list_add(&sub->subscription_list, &subscriber->subscription_list);
371         sub->server_ref = subscriber->port_ref;
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         static struct iovec msg_sect = {NULL, 0};
475
476         struct subscriber *subscriber;
477         u32 server_port_ref;
478
479         /* Create subscriber object */
480
481         subscriber = kzalloc(sizeof(struct subscriber), GFP_ATOMIC);
482         if (subscriber == NULL) {
483                 warn("Subscriber rejected, no memory\n");
484                 return;
485         }
486         INIT_LIST_HEAD(&subscriber->subscription_list);
487         INIT_LIST_HEAD(&subscriber->subscriber_list);
488
489         /* Create server port & establish connection to subscriber */
490
491         tipc_createport(topsrv.user_ref,
492                         subscriber,
493                         importance,
494                         NULL,
495                         NULL,
496                         subscr_conn_shutdown_event,
497                         NULL,
498                         NULL,
499                         subscr_conn_msg_event,
500                         NULL,
501                         &subscriber->port_ref);
502         if (subscriber->port_ref == 0) {
503                 warn("Subscriber rejected, unable to create port\n");
504                 kfree(subscriber);
505                 return;
506         }
507         tipc_connect2port(subscriber->port_ref, orig);
508
509         /* Lock server port (& save lock address for future use) */
510
511         subscriber->lock = tipc_port_lock(subscriber->port_ref)->publ.lock;
512
513         /* Add subscriber to topology server's subscriber list */
514
515         spin_lock_bh(&topsrv.lock);
516         list_add(&subscriber->subscriber_list, &topsrv.subscriber_list);
517         spin_unlock_bh(&topsrv.lock);
518
519         /* Unlock server port */
520
521         server_port_ref = subscriber->port_ref;
522         spin_unlock_bh(subscriber->lock);
523
524         /* Send an ACK- to complete connection handshaking */
525
526         tipc_send(server_port_ref, 1, &msg_sect);
527
528         /* Handle optional subscription request */
529
530         if (size != 0) {
531                 subscr_conn_msg_event(subscriber, server_port_ref,
532                                       buf, data, size);
533         }
534 }
535
536 int tipc_subscr_start(void)
537 {
538         struct tipc_name_seq seq = {TIPC_TOP_SRV, TIPC_TOP_SRV, TIPC_TOP_SRV};
539         int res = -1;
540
541         memset(&topsrv, 0, sizeof (topsrv));
542         spin_lock_init(&topsrv.lock);
543         INIT_LIST_HEAD(&topsrv.subscriber_list);
544
545         spin_lock_bh(&topsrv.lock);
546         res = tipc_attach(&topsrv.user_ref, NULL, NULL);
547         if (res) {
548                 spin_unlock_bh(&topsrv.lock);
549                 return res;
550         }
551
552         res = tipc_createport(topsrv.user_ref,
553                               NULL,
554                               TIPC_CRITICAL_IMPORTANCE,
555                               NULL,
556                               NULL,
557                               NULL,
558                               NULL,
559                               subscr_named_msg_event,
560                               NULL,
561                               NULL,
562                               &topsrv.setup_port);
563         if (res)
564                 goto failed;
565
566         res = tipc_nametbl_publish_rsv(topsrv.setup_port, TIPC_NODE_SCOPE, &seq);
567         if (res)
568                 goto failed;
569
570         spin_unlock_bh(&topsrv.lock);
571         return 0;
572
573 failed:
574         err("Failed to create subscription service\n");
575         tipc_detach(topsrv.user_ref);
576         topsrv.user_ref = 0;
577         spin_unlock_bh(&topsrv.lock);
578         return res;
579 }
580
581 void tipc_subscr_stop(void)
582 {
583         struct subscriber *subscriber;
584         struct subscriber *subscriber_temp;
585         spinlock_t *subscriber_lock;
586
587         if (topsrv.user_ref) {
588                 tipc_deleteport(topsrv.setup_port);
589                 list_for_each_entry_safe(subscriber, subscriber_temp,
590                                          &topsrv.subscriber_list,
591                                          subscriber_list) {
592                         subscriber_lock = subscriber->lock;
593                         spin_lock_bh(subscriber_lock);
594                         subscr_terminate(subscriber);
595                         spin_unlock_bh(subscriber_lock);
596                 }
597                 tipc_detach(topsrv.user_ref);
598                 topsrv.user_ref = 0;
599         }
600 }
601
602
603 int tipc_ispublished(struct tipc_name const *name)
604 {
605         u32 domain = 0;
606
607         return tipc_nametbl_translate(name->type, name->instance, &domain) != 0;
608 }
609