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  * 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
  86 static 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
  98 static 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
 124 int 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
 144 void 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
 164 static 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
 211 static 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
 230 static 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
 285 static 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
 324 static 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
 397 static 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
 421 static 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
 473 static 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
 544 int 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
 581 failed:
 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
 589 void 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 }