linux/net/tipc/subscr.c
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   1/*
   2 * net/tipc/subscr.c: TIPC network topology service
   3 *
   4 * Copyright (c) 2000-2006, Ericsson AB
   5 * Copyright (c) 2005-2007, 2010-2011, 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 "name_table.h"
  39#include "port.h"
  40#include "subscr.h"
  41
  42/**
  43 * struct tipc_subscriber - TIPC network topology subscriber
  44 * @port_ref: object reference to server port connecting to subscriber
  45 * @lock: pointer to spinlock controlling access to subscriber's server port
  46 * @subscriber_list: adjacent subscribers in top. server's list of subscribers
  47 * @subscription_list: list of subscription objects for this subscriber
  48 */
  49
  50struct tipc_subscriber {
  51        u32 port_ref;
  52        spinlock_t *lock;
  53        struct list_head subscriber_list;
  54        struct list_head subscription_list;
  55};
  56
  57/**
  58 * struct top_srv - TIPC network topology subscription service
  59 * @user_ref: TIPC userid of subscription service
  60 * @setup_port: reference to TIPC port that handles subscription requests
  61 * @subscription_count: number of active subscriptions (not subscribers!)
  62 * @subscriber_list: list of ports subscribing to service
  63 * @lock: spinlock govering access to subscriber list
  64 */
  65
  66struct top_srv {
  67        u32 setup_port;
  68        atomic_t subscription_count;
  69        struct list_head subscriber_list;
  70        spinlock_t lock;
  71};
  72
  73static struct top_srv topsrv;
  74
  75/**
  76 * htohl - convert value to endianness used by destination
  77 * @in: value to convert
  78 * @swap: non-zero if endianness must be reversed
  79 *
  80 * Returns converted value
  81 */
  82
  83static u32 htohl(u32 in, int swap)
  84{
  85        return swap ? swab32(in) : in;
  86}
  87
  88/**
  89 * subscr_send_event - send a message containing a tipc_event to the subscriber
  90 *
  91 * Note: Must not hold subscriber's server port lock, since tipc_send() will
  92 *       try to take the lock if the message is rejected and returned!
  93 */
  94
  95static void subscr_send_event(struct tipc_subscription *sub,
  96                              u32 found_lower,
  97                              u32 found_upper,
  98                              u32 event,
  99                              u32 port_ref,
 100                              u32 node)
 101{
 102        struct iovec msg_sect;
 103
 104        msg_sect.iov_base = (void *)&sub->evt;
 105        msg_sect.iov_len = sizeof(struct tipc_event);
 106
 107        sub->evt.event = htohl(event, sub->swap);
 108        sub->evt.found_lower = htohl(found_lower, sub->swap);
 109        sub->evt.found_upper = htohl(found_upper, sub->swap);
 110        sub->evt.port.ref = htohl(port_ref, sub->swap);
 111        sub->evt.port.node = htohl(node, sub->swap);
 112        tipc_send(sub->server_ref, 1, &msg_sect, msg_sect.iov_len);
 113}
 114
 115/**
 116 * tipc_subscr_overlap - test for subscription overlap with the given values
 117 *
 118 * Returns 1 if there is overlap, otherwise 0.
 119 */
 120
 121int tipc_subscr_overlap(struct tipc_subscription *sub,
 122                        u32 found_lower,
 123                        u32 found_upper)
 124
 125{
 126        if (found_lower < sub->seq.lower)
 127                found_lower = sub->seq.lower;
 128        if (found_upper > sub->seq.upper)
 129                found_upper = sub->seq.upper;
 130        if (found_lower > found_upper)
 131                return 0;
 132        return 1;
 133}
 134
 135/**
 136 * tipc_subscr_report_overlap - issue event if there is subscription overlap
 137 *
 138 * Protected by nameseq.lock in name_table.c
 139 */
 140
 141void tipc_subscr_report_overlap(struct tipc_subscription *sub,
 142                                u32 found_lower,
 143                                u32 found_upper,
 144                                u32 event,
 145                                u32 port_ref,
 146                                u32 node,
 147                                int must)
 148{
 149        if (!tipc_subscr_overlap(sub, found_lower, found_upper))
 150                return;
 151        if (!must && !(sub->filter & TIPC_SUB_PORTS))
 152                return;
 153
 154        subscr_send_event(sub, found_lower, found_upper, event, port_ref, node);
 155}
 156
 157/**
 158 * subscr_timeout - subscription timeout has occurred
 159 */
 160
 161static void subscr_timeout(struct tipc_subscription *sub)
 162{
 163        struct tipc_port *server_port;
 164
 165        /* Validate server port reference (in case subscriber is terminating) */
 166
 167        server_port = tipc_port_lock(sub->server_ref);
 168        if (server_port == NULL)
 169                return;
 170
 171        /* Validate timeout (in case subscription is being cancelled) */
 172
 173        if (sub->timeout == TIPC_WAIT_FOREVER) {
 174                tipc_port_unlock(server_port);
 175                return;
 176        }
 177
 178        /* Unlink subscription from name table */
 179
 180        tipc_nametbl_unsubscribe(sub);
 181
 182        /* Unlink subscription from subscriber */
 183
 184        list_del(&sub->subscription_list);
 185
 186        /* Release subscriber's server port */
 187
 188        tipc_port_unlock(server_port);
 189
 190        /* Notify subscriber of timeout */
 191
 192        subscr_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper,
 193                          TIPC_SUBSCR_TIMEOUT, 0, 0);
 194
 195        /* Now destroy subscription */
 196
 197        k_term_timer(&sub->timer);
 198        kfree(sub);
 199        atomic_dec(&topsrv.subscription_count);
 200}
 201
 202/**
 203 * subscr_del - delete a subscription within a subscription list
 204 *
 205 * Called with subscriber port locked.
 206 */
 207
 208static void subscr_del(struct tipc_subscription *sub)
 209{
 210        tipc_nametbl_unsubscribe(sub);
 211        list_del(&sub->subscription_list);
 212        kfree(sub);
 213        atomic_dec(&topsrv.subscription_count);
 214}
 215
 216/**
 217 * subscr_terminate - terminate communication with a subscriber
 218 *
 219 * Called with subscriber port locked.  Routine must temporarily release lock
 220 * to enable subscription timeout routine(s) to finish without deadlocking;
 221 * the lock is then reclaimed to allow caller to release it upon return.
 222 * (This should work even in the unlikely event some other thread creates
 223 * a new object reference in the interim that uses this lock; this routine will
 224 * simply wait for it to be released, then claim it.)
 225 */
 226
 227static void subscr_terminate(struct tipc_subscriber *subscriber)
 228{
 229        u32 port_ref;
 230        struct tipc_subscription *sub;
 231        struct tipc_subscription *sub_temp;
 232
 233        /* Invalidate subscriber reference */
 234
 235        port_ref = subscriber->port_ref;
 236        subscriber->port_ref = 0;
 237        spin_unlock_bh(subscriber->lock);
 238
 239        /* Sever connection to subscriber */
 240
 241        tipc_shutdown(port_ref);
 242        tipc_deleteport(port_ref);
 243
 244        /* Destroy any existing subscriptions for subscriber */
 245
 246        list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
 247                                 subscription_list) {
 248                if (sub->timeout != TIPC_WAIT_FOREVER) {
 249                        k_cancel_timer(&sub->timer);
 250                        k_term_timer(&sub->timer);
 251                }
 252                subscr_del(sub);
 253        }
 254
 255        /* Remove subscriber from topology server's subscriber list */
 256
 257        spin_lock_bh(&topsrv.lock);
 258        list_del(&subscriber->subscriber_list);
 259        spin_unlock_bh(&topsrv.lock);
 260
 261        /* Reclaim subscriber lock */
 262
 263        spin_lock_bh(subscriber->lock);
 264
 265        /* Now destroy subscriber */
 266
 267        kfree(subscriber);
 268}
 269
 270/**
 271 * subscr_cancel - handle subscription cancellation request
 272 *
 273 * Called with subscriber port locked.  Routine must temporarily release lock
 274 * to enable the subscription timeout routine to finish without deadlocking;
 275 * the lock is then reclaimed to allow caller to release it upon return.
 276 *
 277 * Note that fields of 's' use subscriber's endianness!
 278 */
 279
 280static void subscr_cancel(struct tipc_subscr *s,
 281                          struct tipc_subscriber *subscriber)
 282{
 283        struct tipc_subscription *sub;
 284        struct tipc_subscription *sub_temp;
 285        int found = 0;
 286
 287        /* Find first matching subscription, exit if not found */
 288
 289        list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
 290                                 subscription_list) {
 291                if (!memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr))) {
 292                        found = 1;
 293                        break;
 294                }
 295        }
 296        if (!found)
 297                return;
 298
 299        /* Cancel subscription timer (if used), then delete subscription */
 300
 301        if (sub->timeout != TIPC_WAIT_FOREVER) {
 302                sub->timeout = TIPC_WAIT_FOREVER;
 303                spin_unlock_bh(subscriber->lock);
 304                k_cancel_timer(&sub->timer);
 305                k_term_timer(&sub->timer);
 306                spin_lock_bh(subscriber->lock);
 307        }
 308        subscr_del(sub);
 309}
 310
 311/**
 312 * subscr_subscribe - create subscription for subscriber
 313 *
 314 * Called with subscriber port locked.
 315 */
 316
 317static struct tipc_subscription *subscr_subscribe(struct tipc_subscr *s,
 318                                             struct tipc_subscriber *subscriber)
 319{
 320        struct tipc_subscription *sub;
 321        int swap;
 322
 323        /* Determine subscriber's endianness */
 324
 325        swap = !(s->filter & (TIPC_SUB_PORTS | TIPC_SUB_SERVICE));
 326
 327        /* Detect & process a subscription cancellation request */
 328
 329        if (s->filter & htohl(TIPC_SUB_CANCEL, swap)) {
 330                s->filter &= ~htohl(TIPC_SUB_CANCEL, swap);
 331                subscr_cancel(s, subscriber);
 332                return NULL;
 333        }
 334
 335        /* Refuse subscription if global limit exceeded */
 336
 337        if (atomic_read(&topsrv.subscription_count) >= tipc_max_subscriptions) {
 338                warn("Subscription rejected, subscription limit reached (%u)\n",
 339                     tipc_max_subscriptions);
 340                subscr_terminate(subscriber);
 341                return NULL;
 342        }
 343
 344        /* Allocate subscription object */
 345
 346        sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
 347        if (!sub) {
 348                warn("Subscription rejected, no memory\n");
 349                subscr_terminate(subscriber);
 350                return NULL;
 351        }
 352
 353        /* Initialize subscription object */
 354
 355        sub->seq.type = htohl(s->seq.type, swap);
 356        sub->seq.lower = htohl(s->seq.lower, swap);
 357        sub->seq.upper = htohl(s->seq.upper, swap);
 358        sub->timeout = htohl(s->timeout, swap);
 359        sub->filter = htohl(s->filter, swap);
 360        if ((!(sub->filter & TIPC_SUB_PORTS) ==
 361             !(sub->filter & TIPC_SUB_SERVICE)) ||
 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        INIT_LIST_HEAD(&sub->nameseq_list);
 369        list_add(&sub->subscription_list, &subscriber->subscription_list);
 370        sub->server_ref = subscriber->port_ref;
 371        sub->swap = swap;
 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 tipc_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 tipc_subscriber *subscriber = usr_handle;
 420        spinlock_t *subscriber_lock;
 421        struct tipc_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        struct tipc_subscriber *subscriber;
 475        u32 server_port_ref;
 476
 477        /* Create subscriber object */
 478
 479        subscriber = kzalloc(sizeof(struct tipc_subscriber), GFP_ATOMIC);
 480        if (subscriber == NULL) {
 481                warn("Subscriber rejected, no memory\n");
 482                return;
 483        }
 484        INIT_LIST_HEAD(&subscriber->subscription_list);
 485        INIT_LIST_HEAD(&subscriber->subscriber_list);
 486
 487        /* Create server port & establish connection to subscriber */
 488
 489        tipc_createport(subscriber,
 490                        importance,
 491                        NULL,
 492                        NULL,
 493                        subscr_conn_shutdown_event,
 494                        NULL,
 495                        NULL,
 496                        subscr_conn_msg_event,
 497                        NULL,
 498                        &subscriber->port_ref);
 499        if (subscriber->port_ref == 0) {
 500                warn("Subscriber rejected, unable to create port\n");
 501                kfree(subscriber);
 502                return;
 503        }
 504        tipc_connect2port(subscriber->port_ref, orig);
 505
 506        /* Lock server port (& save lock address for future use) */
 507
 508        subscriber->lock = tipc_port_lock(subscriber->port_ref)->lock;
 509
 510        /* Add subscriber to topology server's subscriber list */
 511
 512        spin_lock_bh(&topsrv.lock);
 513        list_add(&subscriber->subscriber_list, &topsrv.subscriber_list);
 514        spin_unlock_bh(&topsrv.lock);
 515
 516        /* Unlock server port */
 517
 518        server_port_ref = subscriber->port_ref;
 519        spin_unlock_bh(subscriber->lock);
 520
 521        /* Send an ACK- to complete connection handshaking */
 522
 523        tipc_send(server_port_ref, 0, NULL, 0);
 524
 525        /* Handle optional subscription request */
 526
 527        if (size != 0) {
 528                subscr_conn_msg_event(subscriber, server_port_ref,
 529                                      buf, data, size);
 530        }
 531}
 532
 533int tipc_subscr_start(void)
 534{
 535        struct tipc_name_seq seq = {TIPC_TOP_SRV, TIPC_TOP_SRV, TIPC_TOP_SRV};
 536        int res;
 537
 538        memset(&topsrv, 0, sizeof(topsrv));
 539        spin_lock_init(&topsrv.lock);
 540        INIT_LIST_HEAD(&topsrv.subscriber_list);
 541
 542        res = tipc_createport(NULL,
 543                              TIPC_CRITICAL_IMPORTANCE,
 544                              NULL,
 545                              NULL,
 546                              NULL,
 547                              NULL,
 548                              subscr_named_msg_event,
 549                              NULL,
 550                              NULL,
 551                              &topsrv.setup_port);
 552        if (res)
 553                goto failed;
 554
 555        res = tipc_nametbl_publish_rsv(topsrv.setup_port, TIPC_NODE_SCOPE, &seq);
 556        if (res) {
 557                tipc_deleteport(topsrv.setup_port);
 558                topsrv.setup_port = 0;
 559                goto failed;
 560        }
 561
 562        return 0;
 563
 564failed:
 565        err("Failed to create subscription service\n");
 566        return res;
 567}
 568
 569void tipc_subscr_stop(void)
 570{
 571        struct tipc_subscriber *subscriber;
 572        struct tipc_subscriber *subscriber_temp;
 573        spinlock_t *subscriber_lock;
 574
 575        if (topsrv.setup_port) {
 576                tipc_deleteport(topsrv.setup_port);
 577                topsrv.setup_port = 0;
 578
 579                list_for_each_entry_safe(subscriber, subscriber_temp,
 580                                         &topsrv.subscriber_list,
 581                                         subscriber_list) {
 582                        subscriber_lock = subscriber->lock;
 583                        spin_lock_bh(subscriber_lock);
 584                        subscr_terminate(subscriber);
 585                        spin_unlock_bh(subscriber_lock);
 586                }
 587        }
 588}
 589