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 "name_table.h"
  39 #include "user_reg.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 user_ref;
  68         u32 setup_port;
  69         atomic_t subscription_count;
  70         struct list_head subscriber_list;
  71         spinlock_t lock;
  72 };
  73
  74 static struct top_srv topsrv = { 0 };
  75
  76 /**
  77  * htohl - convert value to endianness used by destination
  78  * @in: value to convert
  79  * @swap: non-zero if endianness must be reversed
  80  *
  81  * Returns converted value
  82  */
  83
  84 static u32 htohl(u32 in, int swap)
  85 {
  86         return swap ? swab32(in) : in;
  87 }
  88
  89 /**
  90  * subscr_send_event - send a message containing a tipc_event to the subscriber
  91  *
  92  * Note: Must not hold subscriber's server port lock, since tipc_send() will
  93  *       try to take the lock if the message is rejected and returned!
  94  */
  95
  96 static void subscr_send_event(struct subscription *sub,
  97                               u32 found_lower,
  98                               u32 found_upper,
  99                               u32 event,
 100                               u32 port_ref,
 101                               u32 node)
 102 {
 103         struct iovec msg_sect;
 104
 105         msg_sect.iov_base = (void *)&sub->evt;
 106         msg_sect.iov_len = sizeof(struct tipc_event);
 107
 108         sub->evt.event = htohl(event, sub->swap);
 109         sub->evt.found_lower = htohl(found_lower, sub->swap);
 110         sub->evt.found_upper = htohl(found_upper, sub->swap);
 111         sub->evt.port.ref = htohl(port_ref, sub->swap);
 112         sub->evt.port.node = htohl(node, sub->swap);
 113         tipc_send(sub->server_ref, 1, &msg_sect);
 114 }
 115
 116 /**
 117  * tipc_subscr_overlap - test for subscription overlap with the given values
 118  *
 119  * Returns 1 if there is overlap, otherwise 0.
 120  */
 121
 122 int tipc_subscr_overlap(struct subscription *sub,
 123                         u32 found_lower,
 124                         u32 found_upper)
 125
 126 {
 127         if (found_lower < sub->seq.lower)
 128                 found_lower = sub->seq.lower;
 129         if (found_upper > sub->seq.upper)
 130                 found_upper = sub->seq.upper;
 131         if (found_lower > found_upper)
 132                 return 0;
 133         return 1;
 134 }
 135
 136 /**
 137  * tipc_subscr_report_overlap - issue event if there is subscription overlap
 138  *
 139  * Protected by nameseq.lock in name_table.c
 140  */
 141
 142 void tipc_subscr_report_overlap(struct subscription *sub,
 143                                 u32 found_lower,
 144                                 u32 found_upper,
 145                                 u32 event,
 146                                 u32 port_ref,
 147                                 u32 node,
 148                                 int must)
 149 {
 150         if (!tipc_subscr_overlap(sub, found_lower, found_upper))
 151                 return;
 152         if (!must && !(sub->filter & TIPC_SUB_PORTS))
 153                 return;
 154
 155         sub->event_cb(sub, found_lower, found_upper, event, port_ref, node);
 156 }
 157
 158 /**
 159  * subscr_timeout - subscription timeout has occurred
 160  */
 161
 162 static void subscr_timeout(struct subscription *sub)
 163 {
 164         struct port *server_port;
 165
 166         /* Validate server port reference (in case subscriber is terminating) */
 167
 168         server_port = tipc_port_lock(sub->server_ref);
 169         if (server_port == NULL)
 170                 return;
 171
 172         /* Validate timeout (in case subscription is being cancelled) */
 173
 174         if (sub->timeout == TIPC_WAIT_FOREVER) {
 175                 tipc_port_unlock(server_port);
 176                 return;
 177         }
 178
 179         /* Unlink subscription from name table */
 180
 181         tipc_nametbl_unsubscribe(sub);
 182
 183         /* Unlink subscription from subscriber */
 184
 185         list_del(&sub->subscription_list);
 186
 187         /* Release subscriber's server port */
 188
 189         tipc_port_unlock(server_port);
 190
 191         /* Notify subscriber of timeout */
 192
 193         subscr_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper,
 194                           TIPC_SUBSCR_TIMEOUT, 0, 0);
 195
 196         /* Now destroy subscription */
 197
 198         k_term_timer(&sub->timer);
 199         kfree(sub);
 200         atomic_dec(&topsrv.subscription_count);
 201 }
 202
 203 /**
 204  * subscr_del - delete a subscription within a subscription list
 205  *
 206  * Called with subscriber port locked.
 207  */
 208
 209 static void subscr_del(struct subscription *sub)
 210 {
 211         tipc_nametbl_unsubscribe(sub);
 212         list_del(&sub->subscription_list);
 213         kfree(sub);
 214         atomic_dec(&topsrv.subscription_count);
 215 }
 216
 217 /**
 218  * subscr_terminate - terminate communication with a subscriber
 219  *
 220  * Called with subscriber port locked.  Routine must temporarily release lock
 221  * to enable subscription timeout routine(s) to finish without deadlocking;
 222  * the lock is then reclaimed to allow caller to release it upon return.
 223  * (This should work even in the unlikely event some other thread creates
 224  * a new object reference in the interim that uses this lock; this routine will
 225  * simply wait for it to be released, then claim it.)
 226  */
 227
 228 static void subscr_terminate(struct subscriber *subscriber)
 229 {
 230         u32 port_ref;
 231         struct subscription *sub;
 232         struct subscription *sub_temp;
 233
 234         /* Invalidate subscriber reference */
 235
 236         port_ref = subscriber->port_ref;
 237         subscriber->port_ref = 0;
 238         spin_unlock_bh(subscriber->lock);
 239
 240         /* Sever connection to subscriber */
 241
 242         tipc_shutdown(port_ref);
 243         tipc_deleteport(port_ref);
 244
 245         /* Destroy any existing subscriptions for subscriber */
 246
 247         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
 248                                  subscription_list) {
 249                 if (sub->timeout != TIPC_WAIT_FOREVER) {
 250                         k_cancel_timer(&sub->timer);
 251                         k_term_timer(&sub->timer);
 252                 }
 253                 dbg("Term: Removing sub %u,%u,%u from subscriber %x list\n",
 254                     sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
 255                 subscr_del(sub);
 256         }
 257
 258         /* Remove subscriber from topology server's subscriber list */
 259
 260         spin_lock_bh(&topsrv.lock);
 261         list_del(&subscriber->subscriber_list);
 262         spin_unlock_bh(&topsrv.lock);
 263
 264         /* Reclaim subscriber lock */
 265
 266         spin_lock_bh(subscriber->lock);
 267
 268         /* Now destroy subscriber */
 269
 270         kfree(subscriber);
 271 }
 272
 273 /**
 274  * subscr_cancel - handle subscription cancellation request
 275  *
 276  * Called with subscriber port locked.  Routine must temporarily release lock
 277  * to enable the subscription timeout routine to finish without deadlocking;
 278  * the lock is then reclaimed to allow caller to release it upon return.
 279  *
 280  * Note that fields of 's' use subscriber's endianness!
 281  */
 282
 283 static void subscr_cancel(struct tipc_subscr *s,
 284                           struct subscriber *subscriber)
 285 {
 286         struct subscription *sub;
 287         struct subscription *sub_temp;
 288         int found = 0;
 289
 290         /* Find first matching subscription, exit if not found */
 291
 292         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
 293                                  subscription_list) {
 294                 if (!memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr))) {
 295                         found = 1;
 296                         break;
 297                 }
 298         }
 299         if (!found)
 300                 return;
 301
 302         /* Cancel subscription timer (if used), then delete subscription */
 303
 304         if (sub->timeout != TIPC_WAIT_FOREVER) {
 305                 sub->timeout = TIPC_WAIT_FOREVER;
 306                 spin_unlock_bh(subscriber->lock);
 307                 k_cancel_timer(&sub->timer);
 308                 k_term_timer(&sub->timer);
 309                 spin_lock_bh(subscriber->lock);
 310         }
 311         dbg("Cancel: removing sub %u,%u,%u from subscriber %x list\n",
 312             sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
 313         subscr_del(sub);
 314 }
 315
 316 /**
 317  * subscr_subscribe - create subscription for subscriber
 318  *
 319  * Called with subscriber port locked.
 320  */
 321
 322 static struct subscription *subscr_subscribe(struct tipc_subscr *s,
 323                                              struct subscriber *subscriber)
 324 {
 325         struct subscription *sub;
 326         int swap;
 327
 328         /* Determine subscriber's endianness */
 329
 330         swap = !(s->filter & (TIPC_SUB_PORTS | TIPC_SUB_SERVICE));
 331
 332         /* Detect & process a subscription cancellation request */
 333
 334         if (s->filter & htohl(TIPC_SUB_CANCEL, swap)) {
 335                 s->filter &= ~htohl(TIPC_SUB_CANCEL, swap);
 336                 subscr_cancel(s, subscriber);
 337                 return NULL;
 338         }
 339
 340         /* Refuse subscription if global limit exceeded */
 341
 342         if (atomic_read(&topsrv.subscription_count) >= tipc_max_subscriptions) {
 343                 warn("Subscription rejected, subscription limit reached (%u)\n",
 344                      tipc_max_subscriptions);
 345                 subscr_terminate(subscriber);
 346                 return NULL;
 347         }
 348
 349         /* Allocate subscription object */
 350
 351         sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
 352         if (!sub) {
 353                 warn("Subscription rejected, no memory\n");
 354                 subscr_terminate(subscriber);
 355                 return NULL;
 356         }
 357
 358         /* Initialize subscription object */
 359
 360         sub->seq.type = htohl(s->seq.type, swap);
 361         sub->seq.lower = htohl(s->seq.lower, swap);
 362         sub->seq.upper = htohl(s->seq.upper, swap);
 363         sub->timeout = htohl(s->timeout, swap);
 364         sub->filter = htohl(s->filter, swap);
 365         if ((!(sub->filter & TIPC_SUB_PORTS) ==
 366              !(sub->filter & TIPC_SUB_SERVICE)) ||
 367             (sub->seq.lower > sub->seq.upper)) {
 368                 warn("Subscription rejected, illegal request\n");
 369                 kfree(sub);
 370                 subscr_terminate(subscriber);
 371                 return NULL;
 372         }
 373         sub->event_cb = subscr_send_event;
 374         INIT_LIST_HEAD(&sub->nameseq_list);
 375         list_add(&sub->subscription_list, &subscriber->subscription_list);
 376         sub->server_ref = subscriber->port_ref;
 377         sub->swap = swap;
 378         memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
 379         atomic_inc(&topsrv.subscription_count);
 380         if (sub->timeout != TIPC_WAIT_FOREVER) {
 381                 k_init_timer(&sub->timer,
 382                              (Handler)subscr_timeout, (unsigned long)sub);
 383                 k_start_timer(&sub->timer, sub->timeout);
 384         }
 385
 386         return sub;
 387 }
 388
 389 /**
 390  * subscr_conn_shutdown_event - handle termination request from subscriber
 391  *
 392  * Called with subscriber's server port unlocked.
 393  */
 394
 395 static void subscr_conn_shutdown_event(void *usr_handle,
 396                                        u32 port_ref,
 397                                        struct sk_buff **buf,
 398                                        unsigned char const *data,
 399                                        unsigned int size,
 400                                        int reason)
 401 {
 402         struct subscriber *subscriber = usr_handle;
 403         spinlock_t *subscriber_lock;
 404
 405         if (tipc_port_lock(port_ref) == NULL)
 406                 return;
 407
 408         subscriber_lock = subscriber->lock;
 409         subscr_terminate(subscriber);
 410         spin_unlock_bh(subscriber_lock);
 411 }
 412
 413 /**
 414  * subscr_conn_msg_event - handle new subscription request from subscriber
 415  *
 416  * Called with subscriber's server port unlocked.
 417  */
 418
 419 static void subscr_conn_msg_event(void *usr_handle,
 420                                   u32 port_ref,
 421                                   struct sk_buff **buf,
 422                                   const unchar *data,
 423                                   u32 size)
 424 {
 425         struct subscriber *subscriber = usr_handle;
 426         spinlock_t *subscriber_lock;
 427         struct subscription *sub;
 428
 429         /*
 430          * Lock subscriber's server port (& make a local copy of lock pointer,
 431          * in case subscriber is deleted while processing subscription request)
 432          */
 433
 434         if (tipc_port_lock(port_ref) == NULL)
 435                 return;
 436
 437         subscriber_lock = subscriber->lock;
 438
 439         if (size != sizeof(struct tipc_subscr)) {
 440                 subscr_terminate(subscriber);
 441                 spin_unlock_bh(subscriber_lock);
 442         } else {
 443                 sub = subscr_subscribe((struct tipc_subscr *)data, subscriber);
 444                 spin_unlock_bh(subscriber_lock);
 445                 if (sub != NULL) {
 446
 447                         /*
 448                          * We must release the server port lock before adding a
 449                          * subscription to the name table since TIPC needs to be
 450                          * able to (re)acquire the port lock if an event message
 451                          * issued by the subscription process is rejected and
 452                          * returned.  The subscription cannot be deleted while
 453                          * it is being added to the name table because:
 454                          * a) the single-threading of the native API port code
 455                          *    ensures the subscription cannot be cancelled and
 456                          *    the subscriber connection cannot be broken, and
 457                          * b) the name table lock ensures the subscription
 458                          *    timeout code cannot delete the subscription,
 459                          * so the subscription object is still protected.
 460                          */
 461
 462                         tipc_nametbl_subscribe(sub);
 463                 }
 464         }
 465 }
 466
 467 /**
 468  * subscr_named_msg_event - handle request to establish a new subscriber
 469  */
 470
 471 static void subscr_named_msg_event(void *usr_handle,
 472                                    u32 port_ref,
 473                                    struct sk_buff **buf,
 474                                    const unchar *data,
 475                                    u32 size,
 476                                    u32 importance,
 477                                    struct tipc_portid const *orig,
 478                                    struct tipc_name_seq const *dest)
 479 {
 480         static struct iovec msg_sect = {NULL, 0};
 481
 482         struct subscriber *subscriber;
 483         u32 server_port_ref;
 484
 485         /* Create subscriber object */
 486
 487         subscriber = kzalloc(sizeof(struct subscriber), GFP_ATOMIC);
 488         if (subscriber == NULL) {
 489                 warn("Subscriber rejected, no memory\n");
 490                 return;
 491         }
 492         INIT_LIST_HEAD(&subscriber->subscription_list);
 493         INIT_LIST_HEAD(&subscriber->subscriber_list);
 494
 495         /* Create server port & establish connection to subscriber */
 496
 497         tipc_createport(topsrv.user_ref,
 498                         subscriber,
 499                         importance,
 500                         NULL,
 501                         NULL,
 502                         subscr_conn_shutdown_event,
 503                         NULL,
 504                         NULL,
 505                         subscr_conn_msg_event,
 506                         NULL,
 507                         &subscriber->port_ref);
 508         if (subscriber->port_ref == 0) {
 509                 warn("Subscriber rejected, unable to create port\n");
 510                 kfree(subscriber);
 511                 return;
 512         }
 513         tipc_connect2port(subscriber->port_ref, orig);
 514
 515         /* Lock server port (& save lock address for future use) */
 516
 517         subscriber->lock = tipc_port_lock(subscriber->port_ref)->publ.lock;
 518
 519         /* Add subscriber to topology server's subscriber list */
 520
 521         spin_lock_bh(&topsrv.lock);
 522         list_add(&subscriber->subscriber_list, &topsrv.subscriber_list);
 523         spin_unlock_bh(&topsrv.lock);
 524
 525         /* Unlock server port */
 526
 527         server_port_ref = subscriber->port_ref;
 528         spin_unlock_bh(subscriber->lock);
 529
 530         /* Send an ACK- to complete connection handshaking */
 531
 532         tipc_send(server_port_ref, 1, &msg_sect);
 533
 534         /* Handle optional subscription request */
 535
 536         if (size != 0) {
 537                 subscr_conn_msg_event(subscriber, server_port_ref,
 538                                       buf, data, size);
 539         }
 540 }
 541
 542 int tipc_subscr_start(void)
 543 {
 544         struct tipc_name_seq seq = {TIPC_TOP_SRV, TIPC_TOP_SRV, TIPC_TOP_SRV};
 545         int res;
 546
 547         memset(&topsrv, 0, sizeof (topsrv));
 548         spin_lock_init(&topsrv.lock);
 549         INIT_LIST_HEAD(&topsrv.subscriber_list);
 550
 551         spin_lock_bh(&topsrv.lock);
 552         res = tipc_attach(&topsrv.user_ref);
 553         if (res) {
 554                 spin_unlock_bh(&topsrv.lock);
 555                 return res;
 556         }
 557
 558         res = tipc_createport(topsrv.user_ref,
 559                               NULL,
 560                               TIPC_CRITICAL_IMPORTANCE,
 561                               NULL,
 562                               NULL,
 563                               NULL,
 564                               NULL,
 565                               subscr_named_msg_event,
 566                               NULL,
 567                               NULL,
 568                               &topsrv.setup_port);
 569         if (res)
 570                 goto failed;
 571
 572         res = tipc_nametbl_publish_rsv(topsrv.setup_port, TIPC_NODE_SCOPE, &seq);
 573         if (res)
 574                 goto failed;
 575
 576         spin_unlock_bh(&topsrv.lock);
 577         return 0;
 578
 579 failed:
 580         err("Failed to create subscription service\n");
 581         tipc_detach(topsrv.user_ref);
 582         topsrv.user_ref = 0;
 583         spin_unlock_bh(&topsrv.lock);
 584         return res;
 585 }
 586
 587 void tipc_subscr_stop(void)
 588 {
 589         struct subscriber *subscriber;
 590         struct subscriber *subscriber_temp;
 591         spinlock_t *subscriber_lock;
 592
 593         if (topsrv.user_ref) {
 594                 tipc_deleteport(topsrv.setup_port);
 595                 list_for_each_entry_safe(subscriber, subscriber_temp,
 596                                          &topsrv.subscriber_list,
 597                                          subscriber_list) {
 598                         subscriber_lock = subscriber->lock;
 599                         spin_lock_bh(subscriber_lock);
 600                         subscr_terminate(subscriber);
 601                         spin_unlock_bh(subscriber_lock);
 602                 }
 603                 tipc_detach(topsrv.user_ref);
 604                 topsrv.user_ref = 0;
 605         }
 606 }