linux/net/tipc/subscr.c
<<
>>
Prefs
   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