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 * 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
85static 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
111int 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
131void 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
151static 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
198static 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
217static 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
272static 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
324static 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
389static 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
413static 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
465static 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
536int 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
573failed:
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
581void 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
603int 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
610

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