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, 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 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
  50 struct 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
  66 struct top_srv {
  67         u32 setup_port;
  68         atomic_t subscription_count;
  69         struct list_head subscriber_list;
  70         spinlock_t lock;
  71 };
  72
  73 static 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
  83 static 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
  95 static void subscr_send_event(struct 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
 121 int tipc_subscr_overlap(struct 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
 141 void tipc_subscr_report_overlap(struct 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
 161 static void subscr_timeout(struct 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
 208 static void subscr_del(struct 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
 227 static void subscr_terminate(struct subscriber *subscriber)
 228 {
 229         u32 port_ref;
 230         struct subscription *sub;
 231         struct 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
 280 static void subscr_cancel(struct tipc_subscr *s,
 281                           struct subscriber *subscriber)
 282 {
 283         struct subscription *sub;
 284         struct 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
 317 static struct subscription *subscr_subscribe(struct tipc_subscr *s,
 318                                              struct subscriber *subscriber)
 319 {
 320         struct 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
 389 static 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
 413 static 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
 465 static 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 subscriber *subscriber;
 475         u32 server_port_ref;
 476
 477         /* Create subscriber object */
 478
 479         subscriber = kzalloc(sizeof(struct 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
 533 int 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
 564 failed:
 565         err("Failed to create subscription service\n");
 566         return res;
 567 }
 568
 569 void tipc_subscr_stop(void)
 570 {
 571         struct subscriber *subscriber;
 572         struct 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 }