Root/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
52struct 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
68struct 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
76static struct top_srv topsrv = { 0 };
77
78/**
79 * htohl - convert value to endianness used by destination
80 * @in: value to convert
81 * @swap: non-zero if endianness must be reversed
82 *
83 * Returns converted value
84 */
85
86static u32 htohl(u32 in, int swap)
87{
88    return swap ? swab32(in) : in;
89}
90
91/**
92 * subscr_send_event - send a message containing a tipc_event to the subscriber
93 *
94 * Note: Must not hold subscriber's server port lock, since tipc_send() will
95 * try to take the lock if the message is rejected and returned!
96 */
97
98static void subscr_send_event(struct subscription *sub,
99                  u32 found_lower,
100                  u32 found_upper,
101                  u32 event,
102                  u32 port_ref,
103                  u32 node)
104{
105    struct iovec msg_sect;
106
107    msg_sect.iov_base = (void *)&sub->evt;
108    msg_sect.iov_len = sizeof(struct tipc_event);
109
110    sub->evt.event = htohl(event, sub->swap);
111    sub->evt.found_lower = htohl(found_lower, sub->swap);
112    sub->evt.found_upper = htohl(found_upper, sub->swap);
113    sub->evt.port.ref = htohl(port_ref, sub->swap);
114    sub->evt.port.node = htohl(node, sub->swap);
115    tipc_send(sub->server_ref, 1, &msg_sect);
116}
117
118/**
119 * tipc_subscr_overlap - test for subscription overlap with the given values
120 *
121 * Returns 1 if there is overlap, otherwise 0.
122 */
123
124int tipc_subscr_overlap(struct subscription *sub,
125            u32 found_lower,
126            u32 found_upper)
127
128{
129    if (found_lower < sub->seq.lower)
130        found_lower = sub->seq.lower;
131    if (found_upper > sub->seq.upper)
132        found_upper = sub->seq.upper;
133    if (found_lower > found_upper)
134        return 0;
135    return 1;
136}
137
138/**
139 * tipc_subscr_report_overlap - issue event if there is subscription overlap
140 *
141 * Protected by nameseq.lock in name_table.c
142 */
143
144void tipc_subscr_report_overlap(struct subscription *sub,
145                u32 found_lower,
146                u32 found_upper,
147                u32 event,
148                u32 port_ref,
149                u32 node,
150                int must)
151{
152    if (!tipc_subscr_overlap(sub, found_lower, found_upper))
153        return;
154    if (!must && !(sub->filter & TIPC_SUB_PORTS))
155        return;
156
157    sub->event_cb(sub, found_lower, found_upper, event, port_ref, node);
158}
159
160/**
161 * subscr_timeout - subscription timeout has occurred
162 */
163
164static void subscr_timeout(struct subscription *sub)
165{
166    struct port *server_port;
167
168    /* Validate server port reference (in case subscriber is terminating) */
169
170    server_port = tipc_port_lock(sub->server_ref);
171    if (server_port == NULL)
172        return;
173
174    /* Validate timeout (in case subscription is being cancelled) */
175
176    if (sub->timeout == TIPC_WAIT_FOREVER) {
177        tipc_port_unlock(server_port);
178        return;
179    }
180
181    /* Unlink subscription from name table */
182
183    tipc_nametbl_unsubscribe(sub);
184
185    /* Unlink subscription from subscriber */
186
187    list_del(&sub->subscription_list);
188
189    /* Release subscriber's server port */
190
191    tipc_port_unlock(server_port);
192
193    /* Notify subscriber of timeout */
194
195    subscr_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper,
196              TIPC_SUBSCR_TIMEOUT, 0, 0);
197
198    /* Now destroy subscription */
199
200    k_term_timer(&sub->timer);
201    kfree(sub);
202    atomic_dec(&topsrv.subscription_count);
203}
204
205/**
206 * subscr_del - delete a subscription within a subscription list
207 *
208 * Called with subscriber port locked.
209 */
210
211static void subscr_del(struct subscription *sub)
212{
213    tipc_nametbl_unsubscribe(sub);
214    list_del(&sub->subscription_list);
215    kfree(sub);
216    atomic_dec(&topsrv.subscription_count);
217}
218
219/**
220 * subscr_terminate - terminate communication with a subscriber
221 *
222 * Called with subscriber port locked. Routine must temporarily release lock
223 * to enable subscription timeout routine(s) to finish without deadlocking;
224 * the lock is then reclaimed to allow caller to release it upon return.
225 * (This should work even in the unlikely event some other thread creates
226 * a new object reference in the interim that uses this lock; this routine will
227 * simply wait for it to be released, then claim it.)
228 */
229
230static void subscr_terminate(struct subscriber *subscriber)
231{
232    u32 port_ref;
233    struct subscription *sub;
234    struct subscription *sub_temp;
235
236    /* Invalidate subscriber reference */
237
238    port_ref = subscriber->port_ref;
239    subscriber->port_ref = 0;
240    spin_unlock_bh(subscriber->lock);
241
242    /* Sever connection to subscriber */
243
244    tipc_shutdown(port_ref);
245    tipc_deleteport(port_ref);
246
247    /* Destroy any existing subscriptions for subscriber */
248
249    list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
250                 subscription_list) {
251        if (sub->timeout != TIPC_WAIT_FOREVER) {
252            k_cancel_timer(&sub->timer);
253            k_term_timer(&sub->timer);
254        }
255        dbg("Term: Removing sub %u,%u,%u from subscriber %x list\n",
256            sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
257        subscr_del(sub);
258    }
259
260    /* Remove subscriber from topology server's subscriber list */
261
262    spin_lock_bh(&topsrv.lock);
263    list_del(&subscriber->subscriber_list);
264    spin_unlock_bh(&topsrv.lock);
265
266    /* Reclaim subscriber lock */
267
268    spin_lock_bh(subscriber->lock);
269
270    /* Now destroy subscriber */
271
272    kfree(subscriber);
273}
274
275/**
276 * subscr_cancel - handle subscription cancellation request
277 *
278 * Called with subscriber port locked. Routine must temporarily release lock
279 * to enable the subscription timeout routine to finish without deadlocking;
280 * the lock is then reclaimed to allow caller to release it upon return.
281 *
282 * Note that fields of 's' use subscriber's endianness!
283 */
284
285static void subscr_cancel(struct tipc_subscr *s,
286              struct subscriber *subscriber)
287{
288    struct subscription *sub;
289    struct subscription *sub_temp;
290    int found = 0;
291
292    /* Find first matching subscription, exit if not found */
293
294    list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
295                 subscription_list) {
296        if (!memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr))) {
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 %x 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
324static struct subscription *subscr_subscribe(struct tipc_subscr *s,
325                         struct subscriber *subscriber)
326{
327    struct subscription *sub;
328    int swap;
329
330    /* Determine subscriber's endianness */
331
332    swap = !(s->filter & (TIPC_SUB_PORTS | TIPC_SUB_SERVICE));
333
334    /* Detect & process a subscription cancellation request */
335
336    if (s->filter & htohl(TIPC_SUB_CANCEL, swap)) {
337        s->filter &= ~htohl(TIPC_SUB_CANCEL, swap);
338        subscr_cancel(s, subscriber);
339        return NULL;
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 NULL;
349    }
350
351    /* Allocate subscription object */
352
353    sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
354    if (!sub) {
355        warn("Subscription rejected, no memory\n");
356        subscr_terminate(subscriber);
357        return NULL;
358    }
359
360    /* Initialize subscription object */
361
362    sub->seq.type = htohl(s->seq.type, swap);
363    sub->seq.lower = htohl(s->seq.lower, swap);
364    sub->seq.upper = htohl(s->seq.upper, swap);
365    sub->timeout = htohl(s->timeout, swap);
366    sub->filter = htohl(s->filter, 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 NULL;
374    }
375    sub->event_cb = subscr_send_event;
376    INIT_LIST_HEAD(&sub->nameseq_list);
377    list_add(&sub->subscription_list, &subscriber->subscription_list);
378    sub->server_ref = subscriber->port_ref;
379    sub->swap = swap;
380    memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
381    atomic_inc(&topsrv.subscription_count);
382    if (sub->timeout != TIPC_WAIT_FOREVER) {
383        k_init_timer(&sub->timer,
384                 (Handler)subscr_timeout, (unsigned long)sub);
385        k_start_timer(&sub->timer, sub->timeout);
386    }
387
388    return sub;
389}
390
391/**
392 * subscr_conn_shutdown_event - handle termination request from subscriber
393 *
394 * Called with subscriber's server port unlocked.
395 */
396
397static void subscr_conn_shutdown_event(void *usr_handle,
398                       u32 port_ref,
399                       struct sk_buff **buf,
400                       unsigned char const *data,
401                       unsigned int size,
402                       int reason)
403{
404    struct subscriber *subscriber = usr_handle;
405    spinlock_t *subscriber_lock;
406
407    if (tipc_port_lock(port_ref) == NULL)
408        return;
409
410    subscriber_lock = subscriber->lock;
411    subscr_terminate(subscriber);
412    spin_unlock_bh(subscriber_lock);
413}
414
415/**
416 * subscr_conn_msg_event - handle new subscription request from subscriber
417 *
418 * Called with subscriber's server port unlocked.
419 */
420
421static void subscr_conn_msg_event(void *usr_handle,
422                  u32 port_ref,
423                  struct sk_buff **buf,
424                  const unchar *data,
425                  u32 size)
426{
427    struct subscriber *subscriber = usr_handle;
428    spinlock_t *subscriber_lock;
429    struct subscription *sub;
430
431    /*
432     * Lock subscriber's server port (& make a local copy of lock pointer,
433     * in case subscriber is deleted while processing subscription request)
434     */
435
436    if (tipc_port_lock(port_ref) == NULL)
437        return;
438
439    subscriber_lock = subscriber->lock;
440
441    if (size != sizeof(struct tipc_subscr)) {
442        subscr_terminate(subscriber);
443        spin_unlock_bh(subscriber_lock);
444    } else {
445        sub = subscr_subscribe((struct tipc_subscr *)data, subscriber);
446        spin_unlock_bh(subscriber_lock);
447        if (sub != NULL) {
448
449            /*
450             * We must release the server port lock before adding a
451             * subscription to the name table since TIPC needs to be
452             * able to (re)acquire the port lock if an event message
453             * issued by the subscription process is rejected and
454             * returned. The subscription cannot be deleted while
455             * it is being added to the name table because:
456             * a) the single-threading of the native API port code
457             * ensures the subscription cannot be cancelled and
458             * the subscriber connection cannot be broken, and
459             * b) the name table lock ensures the subscription
460             * timeout code cannot delete the subscription,
461             * so the subscription object is still protected.
462             */
463
464            tipc_nametbl_subscribe(sub);
465        }
466    }
467}
468
469/**
470 * subscr_named_msg_event - handle request to establish a new subscriber
471 */
472
473static void subscr_named_msg_event(void *usr_handle,
474                   u32 port_ref,
475                   struct sk_buff **buf,
476                   const unchar *data,
477                   u32 size,
478                   u32 importance,
479                   struct tipc_portid const *orig,
480                   struct tipc_name_seq const *dest)
481{
482    static struct iovec msg_sect = {NULL, 0};
483
484    struct subscriber *subscriber;
485    u32 server_port_ref;
486
487    /* Create subscriber object */
488
489    subscriber = kzalloc(sizeof(struct subscriber), GFP_ATOMIC);
490    if (subscriber == NULL) {
491        warn("Subscriber rejected, no memory\n");
492        return;
493    }
494    INIT_LIST_HEAD(&subscriber->subscription_list);
495    INIT_LIST_HEAD(&subscriber->subscriber_list);
496
497    /* Create server port & establish connection to subscriber */
498
499    tipc_createport(topsrv.user_ref,
500            subscriber,
501            importance,
502            NULL,
503            NULL,
504            subscr_conn_shutdown_event,
505            NULL,
506            NULL,
507            subscr_conn_msg_event,
508            NULL,
509            &subscriber->port_ref);
510    if (subscriber->port_ref == 0) {
511        warn("Subscriber rejected, unable to create port\n");
512        kfree(subscriber);
513        return;
514    }
515    tipc_connect2port(subscriber->port_ref, orig);
516
517    /* Lock server port (& save lock address for future use) */
518
519    subscriber->lock = tipc_port_lock(subscriber->port_ref)->publ.lock;
520
521    /* Add subscriber to topology server's subscriber list */
522
523    spin_lock_bh(&topsrv.lock);
524    list_add(&subscriber->subscriber_list, &topsrv.subscriber_list);
525    spin_unlock_bh(&topsrv.lock);
526
527    /* Unlock server port */
528
529    server_port_ref = subscriber->port_ref;
530    spin_unlock_bh(subscriber->lock);
531
532    /* Send an ACK- to complete connection handshaking */
533
534    tipc_send(server_port_ref, 1, &msg_sect);
535
536    /* Handle optional subscription request */
537
538    if (size != 0) {
539        subscr_conn_msg_event(subscriber, server_port_ref,
540                      buf, data, size);
541    }
542}
543
544int tipc_subscr_start(void)
545{
546    struct tipc_name_seq seq = {TIPC_TOP_SRV, TIPC_TOP_SRV, TIPC_TOP_SRV};
547    int res = -1;
548
549    memset(&topsrv, 0, sizeof (topsrv));
550    spin_lock_init(&topsrv.lock);
551    INIT_LIST_HEAD(&topsrv.subscriber_list);
552
553    spin_lock_bh(&topsrv.lock);
554    res = tipc_attach(&topsrv.user_ref, NULL, NULL);
555    if (res) {
556        spin_unlock_bh(&topsrv.lock);
557        return res;
558    }
559
560    res = tipc_createport(topsrv.user_ref,
561                  NULL,
562                  TIPC_CRITICAL_IMPORTANCE,
563                  NULL,
564                  NULL,
565                  NULL,
566                  NULL,
567                  subscr_named_msg_event,
568                  NULL,
569                  NULL,
570                  &topsrv.setup_port);
571    if (res)
572        goto failed;
573
574    res = tipc_nametbl_publish_rsv(topsrv.setup_port, TIPC_NODE_SCOPE, &seq);
575    if (res)
576        goto failed;
577
578    spin_unlock_bh(&topsrv.lock);
579    return 0;
580
581failed:
582    err("Failed to create subscription service\n");
583    tipc_detach(topsrv.user_ref);
584    topsrv.user_ref = 0;
585    spin_unlock_bh(&topsrv.lock);
586    return res;
587}
588
589void tipc_subscr_stop(void)
590{
591    struct subscriber *subscriber;
592    struct subscriber *subscriber_temp;
593    spinlock_t *subscriber_lock;
594
595    if (topsrv.user_ref) {
596        tipc_deleteport(topsrv.setup_port);
597        list_for_each_entry_safe(subscriber, subscriber_temp,
598                     &topsrv.subscriber_list,
599                     subscriber_list) {
600            subscriber_lock = subscriber->lock;
601            spin_lock_bh(subscriber_lock);
602            subscr_terminate(subscriber);
603            spin_unlock_bh(subscriber_lock);
604        }
605        tipc_detach(topsrv.user_ref);
606        topsrv.user_ref = 0;
607    }
608}
609
610
611int tipc_ispublished(struct tipc_name const *name)
612{
613    u32 domain = 0;
614
615    return(tipc_nametbl_translate(name->type, name->instance,&domain) != 0);
616}
617
618

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