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  * 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
  85 static 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
 111 int 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
 131 void 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
 151 static 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
 198 static 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
 217 static 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
 272 static 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;
 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
 286         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
 287                                  subscription_list) {
 288                         if ((type == sub->seq.type) &&
 289                             (lower == sub->seq.lower) &&
 290                             (upper == sub->seq.upper)) {
 291                                 found = 1;
 292                                 break;
 293                         }
 294         }
 295         if (!found)
 296                 return;
 297
 298         /* Cancel subscription timer (if used), then delete subscription */
 299
 300         if (sub->timeout != TIPC_WAIT_FOREVER) {
 301                 sub->timeout = TIPC_WAIT_FOREVER;
 302                 spin_unlock_bh(subscriber->lock);
 303                 k_cancel_timer(&sub->timer);
 304                 k_term_timer(&sub->timer);
 305                 spin_lock_bh(subscriber->lock);
 306         }
 307         dbg("Cancel: removing sub %u,%u,%u from subscriber %x list\n",
 308             sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
 309         subscr_del(sub);
 310 }
 311
 312 /**
 313  * subscr_subscribe - create subscription for subscriber
 314  *
 315  * Called with subscriber port locked.
 316  */
 317
 318 static struct subscription *subscr_subscribe(struct tipc_subscr *s,
 319                                              struct subscriber *subscriber)
 320 {
 321         struct subscription *sub;
 322
 323         /* Detect & process a subscription cancellation request */
 324
 325         if (ntohl(s->filter) & TIPC_SUB_CANCEL) {
 326                 subscr_cancel(s, subscriber);
 327                 return NULL;
 328         }
 329
 330         /* Refuse subscription if global limit exceeded */
 331
 332         if (atomic_read(&topsrv.subscription_count) >= tipc_max_subscriptions) {
 333                 warn("Subscription rejected, subscription limit reached (%u)\n",
 334                      tipc_max_subscriptions);
 335                 subscr_terminate(subscriber);
 336                 return NULL;
 337         }
 338
 339         /* Allocate subscription object */
 340
 341         sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
 342         if (!sub) {
 343                 warn("Subscription rejected, no memory\n");
 344                 subscr_terminate(subscriber);
 345                 return NULL;
 346         }
 347
 348         /* Initialize subscription object */
 349
 350         sub->seq.type = ntohl(s->seq.type);
 351         sub->seq.lower = ntohl(s->seq.lower);
 352         sub->seq.upper = ntohl(s->seq.upper);
 353         sub->timeout = ntohl(s->timeout);
 354         sub->filter = ntohl(s->filter);
 355         if ((!(sub->filter & TIPC_SUB_PORTS) ==
 356              !(sub->filter & TIPC_SUB_SERVICE)) ||
 357             (sub->seq.lower > sub->seq.upper)) {
 358                 warn("Subscription rejected, illegal request\n");
 359                 kfree(sub);
 360                 subscr_terminate(subscriber);
 361                 return NULL;
 362         }
 363         sub->event_cb = subscr_send_event;
 364         INIT_LIST_HEAD(&sub->nameseq_list);
 365         list_add(&sub->subscription_list, &subscriber->subscription_list);
 366         sub->server_ref = subscriber->port_ref;
 367         memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
 368         atomic_inc(&topsrv.subscription_count);
 369         if (sub->timeout != TIPC_WAIT_FOREVER) {
 370                 k_init_timer(&sub->timer,
 371                              (Handler)subscr_timeout, (unsigned long)sub);
 372                 k_start_timer(&sub->timer, sub->timeout);
 373         }
 374
 375         return sub;
 376 }
 377
 378 /**
 379  * subscr_conn_shutdown_event - handle termination request from subscriber
 380  *
 381  * Called with subscriber's server port unlocked.
 382  */
 383
 384 static void subscr_conn_shutdown_event(void *usr_handle,
 385                                        u32 port_ref,
 386                                        struct sk_buff **buf,
 387                                        unsigned char const *data,
 388                                        unsigned int size,
 389                                        int reason)
 390 {
 391         struct subscriber *subscriber = usr_handle;
 392         spinlock_t *subscriber_lock;
 393
 394         if (tipc_port_lock(port_ref) == NULL)
 395                 return;
 396
 397         subscriber_lock = subscriber->lock;
 398         subscr_terminate(subscriber);
 399         spin_unlock_bh(subscriber_lock);
 400 }
 401
 402 /**
 403  * subscr_conn_msg_event - handle new subscription request from subscriber
 404  *
 405  * Called with subscriber's server port unlocked.
 406  */
 407
 408 static void subscr_conn_msg_event(void *usr_handle,
 409                                   u32 port_ref,
 410                                   struct sk_buff **buf,
 411                                   const unchar *data,
 412                                   u32 size)
 413 {
 414         struct subscriber *subscriber = usr_handle;
 415         spinlock_t *subscriber_lock;
 416         struct subscription *sub;
 417
 418         /*
 419          * Lock subscriber's server port (& make a local copy of lock pointer,
 420          * in case subscriber is deleted while processing subscription request)
 421          */
 422
 423         if (tipc_port_lock(port_ref) == NULL)
 424                 return;
 425
 426         subscriber_lock = subscriber->lock;
 427
 428         if (size != sizeof(struct tipc_subscr)) {
 429                 subscr_terminate(subscriber);
 430                 spin_unlock_bh(subscriber_lock);
 431         } else {
 432                 sub = subscr_subscribe((struct tipc_subscr *)data, subscriber);
 433                 spin_unlock_bh(subscriber_lock);
 434                 if (sub != NULL) {
 435
 436                         /*
 437                          * We must release the server port lock before adding a
 438                          * subscription to the name table since TIPC needs to be
 439                          * able to (re)acquire the port lock if an event message
 440                          * issued by the subscription process is rejected and
 441                          * returned.  The subscription cannot be deleted while
 442                          * it is being added to the name table because:
 443                          * a) the single-threading of the native API port code
 444                          *    ensures the subscription cannot be cancelled and
 445                          *    the subscriber connection cannot be broken, and
 446                          * b) the name table lock ensures the subscription
 447                          *    timeout code cannot delete the subscription,
 448                          * so the subscription object is still protected.
 449                          */
 450
 451                         tipc_nametbl_subscribe(sub);
 452                 }
 453         }
 454 }
 455
 456 /**
 457  * subscr_named_msg_event - handle request to establish a new subscriber
 458  */
 459
 460 static void subscr_named_msg_event(void *usr_handle,
 461                                    u32 port_ref,
 462                                    struct sk_buff **buf,
 463                                    const unchar *data,
 464                                    u32 size,
 465                                    u32 importance,
 466                                    struct tipc_portid const *orig,
 467                                    struct tipc_name_seq const *dest)
 468 {
 469         static struct iovec msg_sect = {NULL, 0};
 470
 471         struct subscriber *subscriber;
 472         u32 server_port_ref;
 473
 474         /* Create subscriber object */
 475
 476         subscriber = kzalloc(sizeof(struct subscriber), GFP_ATOMIC);
 477         if (subscriber == NULL) {
 478                 warn("Subscriber rejected, no memory\n");
 479                 return;
 480         }
 481         INIT_LIST_HEAD(&subscriber->subscription_list);
 482         INIT_LIST_HEAD(&subscriber->subscriber_list);
 483
 484         /* Create server port & establish connection to subscriber */
 485
 486         tipc_createport(topsrv.user_ref,
 487                         subscriber,
 488                         importance,
 489                         NULL,
 490                         NULL,
 491                         subscr_conn_shutdown_event,
 492                         NULL,
 493                         NULL,
 494                         subscr_conn_msg_event,
 495                         NULL,
 496                         &subscriber->port_ref);
 497         if (subscriber->port_ref == 0) {
 498                 warn("Subscriber rejected, unable to create port\n");
 499                 kfree(subscriber);
 500                 return;
 501         }
 502         tipc_connect2port(subscriber->port_ref, orig);
 503
 504         /* Lock server port (& save lock address for future use) */
 505
 506         subscriber->lock = tipc_port_lock(subscriber->port_ref)->publ.lock;
 507
 508         /* Add subscriber to topology server's subscriber list */
 509
 510         spin_lock_bh(&topsrv.lock);
 511         list_add(&subscriber->subscriber_list, &topsrv.subscriber_list);
 512         spin_unlock_bh(&topsrv.lock);
 513
 514         /* Unlock server port */
 515
 516         server_port_ref = subscriber->port_ref;
 517         spin_unlock_bh(subscriber->lock);
 518
 519         /* Send an ACK- to complete connection handshaking */
 520
 521         tipc_send(server_port_ref, 1, &msg_sect);
 522
 523         /* Handle optional subscription request */
 524
 525         if (size != 0) {
 526                 subscr_conn_msg_event(subscriber, server_port_ref,
 527                                       buf, data, size);
 528         }
 529 }
 530
 531 int tipc_subscr_start(void)
 532 {
 533         struct tipc_name_seq seq = {TIPC_TOP_SRV, TIPC_TOP_SRV, TIPC_TOP_SRV};
 534         int res = -1;
 535
 536         memset(&topsrv, 0, sizeof (topsrv));
 537         spin_lock_init(&topsrv.lock);
 538         INIT_LIST_HEAD(&topsrv.subscriber_list);
 539
 540         spin_lock_bh(&topsrv.lock);
 541         res = tipc_attach(&topsrv.user_ref, NULL, NULL);
 542         if (res) {
 543                 spin_unlock_bh(&topsrv.lock);
 544                 return res;
 545         }
 546
 547         res = tipc_createport(topsrv.user_ref,
 548                               NULL,
 549                               TIPC_CRITICAL_IMPORTANCE,
 550                               NULL,
 551                               NULL,
 552                               NULL,
 553                               NULL,
 554                               subscr_named_msg_event,
 555                               NULL,
 556                               NULL,
 557                               &topsrv.setup_port);
 558         if (res)
 559                 goto failed;
 560
 561         res = tipc_nametbl_publish_rsv(topsrv.setup_port, TIPC_NODE_SCOPE, &seq);
 562         if (res)
 563                 goto failed;
 564
 565         spin_unlock_bh(&topsrv.lock);
 566         return 0;
 567
 568 failed:
 569         err("Failed to create subscription service\n");
 570         tipc_detach(topsrv.user_ref);
 571         topsrv.user_ref = 0;
 572         spin_unlock_bh(&topsrv.lock);
 573         return res;
 574 }
 575
 576 void tipc_subscr_stop(void)
 577 {
 578         struct subscriber *subscriber;
 579         struct subscriber *subscriber_temp;
 580         spinlock_t *subscriber_lock;
 581
 582         if (topsrv.user_ref) {
 583                 tipc_deleteport(topsrv.setup_port);
 584                 list_for_each_entry_safe(subscriber, subscriber_temp,
 585                                          &topsrv.subscriber_list,
 586                                          subscriber_list) {
 587                         subscriber_lock = subscriber->lock;
 588                         spin_lock_bh(subscriber_lock);
 589                         subscr_terminate(subscriber);
 590                         spin_unlock_bh(subscriber_lock);
 591                 }
 592                 tipc_detach(topsrv.user_ref);
 593                 topsrv.user_ref = 0;
 594         }
 595 }
 596
 597
 598 int tipc_ispublished(struct tipc_name const *name)
 599 {
 600         u32 domain = 0;
 601
 602         return(tipc_nametbl_translate(name->type, name->instance,&domain) != 0);
 603 }
 604