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 tipc_subscriber - TIPC network topology subscriber
  44  * @port_ref: object reference to server port connecting to subscriber
  45  * @lock: pointer to spinlock controlling access to subscriber's server port
  46  * @subscriber_list: adjacent subscribers in top. server's list of subscribers
  47  * @subscription_list: list of subscription objects for this subscriber
  48  */
  49 struct tipc_subscriber {
  50         u32 port_ref;
  51         spinlock_t *lock;
  52         struct list_head subscriber_list;
  53         struct list_head subscription_list;
  54 };
  55
  56 /**
  57  * struct top_srv - TIPC network topology subscription service
  58  * @setup_port: reference to TIPC port that handles subscription requests
  59  * @subscription_count: number of active subscriptions (not subscribers!)
  60  * @subscriber_list: list of ports subscribing to service
  61  * @lock: spinlock govering access to subscriber list
  62  */
  63 struct top_srv {
  64         u32 setup_port;
  65         atomic_t subscription_count;
  66         struct list_head subscriber_list;
  67         spinlock_t lock;
  68 };
  69
  70 static struct top_srv topsrv;
  71
  72 /**
  73  * htohl - convert value to endianness used by destination
  74  * @in: value to convert
  75  * @swap: non-zero if endianness must be reversed
  76  *
  77  * Returns converted value
  78  */
  79 static u32 htohl(u32 in, int swap)
  80 {
  81         return swap ? swab32(in) : in;
  82 }
  83
  84 /**
  85  * subscr_send_event - send a message containing a tipc_event to the subscriber
  86  *
  87  * Note: Must not hold subscriber's server port lock, since tipc_send() will
  88  *       try to take the lock if the message is rejected and returned!
  89  */
  90 static void subscr_send_event(struct tipc_subscription *sub,
  91                               u32 found_lower,
  92                               u32 found_upper,
  93                               u32 event,
  94                               u32 port_ref,
  95                               u32 node)
  96 {
  97         struct iovec msg_sect;
  98
  99         msg_sect.iov_base = (void *)&sub->evt;
 100         msg_sect.iov_len = sizeof(struct tipc_event);
 101
 102         sub->evt.event = htohl(event, sub->swap);
 103         sub->evt.found_lower = htohl(found_lower, sub->swap);
 104         sub->evt.found_upper = htohl(found_upper, sub->swap);
 105         sub->evt.port.ref = htohl(port_ref, sub->swap);
 106         sub->evt.port.node = htohl(node, sub->swap);
 107         tipc_send(sub->server_ref, 1, &msg_sect, msg_sect.iov_len);
 108 }
 109
 110 /**
 111  * tipc_subscr_overlap - test for subscription overlap with the given values
 112  *
 113  * Returns 1 if there is overlap, otherwise 0.
 114  */
 115 int tipc_subscr_overlap(struct tipc_subscription *sub,
 116                         u32 found_lower,
 117                         u32 found_upper)
 118
 119 {
 120         if (found_lower < sub->seq.lower)
 121                 found_lower = sub->seq.lower;
 122         if (found_upper > sub->seq.upper)
 123                 found_upper = sub->seq.upper;
 124         if (found_lower > found_upper)
 125                 return 0;
 126         return 1;
 127 }
 128
 129 /**
 130  * tipc_subscr_report_overlap - issue event if there is subscription overlap
 131  *
 132  * Protected by nameseq.lock in name_table.c
 133  */
 134 void tipc_subscr_report_overlap(struct tipc_subscription *sub,
 135                                 u32 found_lower,
 136                                 u32 found_upper,
 137                                 u32 event,
 138                                 u32 port_ref,
 139                                 u32 node,
 140                                 int must)
 141 {
 142         if (!tipc_subscr_overlap(sub, found_lower, found_upper))
 143                 return;
 144         if (!must && !(sub->filter & TIPC_SUB_PORTS))
 145                 return;
 146
 147         subscr_send_event(sub, found_lower, found_upper, event, port_ref, node);
 148 }
 149
 150 /**
 151  * subscr_timeout - subscription timeout has occurred
 152  */
 153 static void subscr_timeout(struct tipc_subscription *sub)
 154 {
 155         struct tipc_port *server_port;
 156
 157         /* Validate server port reference (in case subscriber is terminating) */
 158         server_port = tipc_port_lock(sub->server_ref);
 159         if (server_port == NULL)
 160                 return;
 161
 162         /* Validate timeout (in case subscription is being cancelled) */
 163         if (sub->timeout == TIPC_WAIT_FOREVER) {
 164                 tipc_port_unlock(server_port);
 165                 return;
 166         }
 167
 168         /* Unlink subscription from name table */
 169         tipc_nametbl_unsubscribe(sub);
 170
 171         /* Unlink subscription from subscriber */
 172         list_del(&sub->subscription_list);
 173
 174         /* Release subscriber's server port */
 175         tipc_port_unlock(server_port);
 176
 177         /* Notify subscriber of timeout */
 178         subscr_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper,
 179                           TIPC_SUBSCR_TIMEOUT, 0, 0);
 180
 181         /* Now destroy subscription */
 182         k_term_timer(&sub->timer);
 183         kfree(sub);
 184         atomic_dec(&topsrv.subscription_count);
 185 }
 186
 187 /**
 188  * subscr_del - delete a subscription within a subscription list
 189  *
 190  * Called with subscriber port locked.
 191  */
 192 static void subscr_del(struct tipc_subscription *sub)
 193 {
 194         tipc_nametbl_unsubscribe(sub);
 195         list_del(&sub->subscription_list);
 196         kfree(sub);
 197         atomic_dec(&topsrv.subscription_count);
 198 }
 199
 200 /**
 201  * subscr_terminate - terminate communication with a subscriber
 202  *
 203  * Called with subscriber port locked.  Routine must temporarily release lock
 204  * to enable subscription timeout routine(s) to finish without deadlocking;
 205  * the lock is then reclaimed to allow caller to release it upon return.
 206  * (This should work even in the unlikely event some other thread creates
 207  * a new object reference in the interim that uses this lock; this routine will
 208  * simply wait for it to be released, then claim it.)
 209  */
 210 static void subscr_terminate(struct tipc_subscriber *subscriber)
 211 {
 212         u32 port_ref;
 213         struct tipc_subscription *sub;
 214         struct tipc_subscription *sub_temp;
 215
 216         /* Invalidate subscriber reference */
 217         port_ref = subscriber->port_ref;
 218         subscriber->port_ref = 0;
 219         spin_unlock_bh(subscriber->lock);
 220
 221         /* Sever connection to subscriber */
 222         tipc_shutdown(port_ref);
 223         tipc_deleteport(port_ref);
 224
 225         /* Destroy any existing subscriptions for subscriber */
 226         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
 227                                  subscription_list) {
 228                 if (sub->timeout != TIPC_WAIT_FOREVER) {
 229                         k_cancel_timer(&sub->timer);
 230                         k_term_timer(&sub->timer);
 231                 }
 232                 subscr_del(sub);
 233         }
 234
 235         /* Remove subscriber from topology server's subscriber list */
 236         spin_lock_bh(&topsrv.lock);
 237         list_del(&subscriber->subscriber_list);
 238         spin_unlock_bh(&topsrv.lock);
 239
 240         /* Reclaim subscriber lock */
 241         spin_lock_bh(subscriber->lock);
 242
 243         /* Now destroy subscriber */
 244         kfree(subscriber);
 245 }
 246
 247 /**
 248  * subscr_cancel - handle subscription cancellation request
 249  *
 250  * Called with subscriber port locked.  Routine must temporarily release lock
 251  * to enable the subscription timeout routine to finish without deadlocking;
 252  * the lock is then reclaimed to allow caller to release it upon return.
 253  *
 254  * Note that fields of 's' use subscriber's endianness!
 255  */
 256 static void subscr_cancel(struct tipc_subscr *s,
 257                           struct tipc_subscriber *subscriber)
 258 {
 259         struct tipc_subscription *sub;
 260         struct tipc_subscription *sub_temp;
 261         int found = 0;
 262
 263         /* Find first matching subscription, exit if not found */
 264         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
 265                                  subscription_list) {
 266                 if (!memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr))) {
 267                         found = 1;
 268                         break;
 269                 }
 270         }
 271         if (!found)
 272                 return;
 273
 274         /* Cancel subscription timer (if used), then delete subscription */
 275         if (sub->timeout != TIPC_WAIT_FOREVER) {
 276                 sub->timeout = TIPC_WAIT_FOREVER;
 277                 spin_unlock_bh(subscriber->lock);
 278                 k_cancel_timer(&sub->timer);
 279                 k_term_timer(&sub->timer);
 280                 spin_lock_bh(subscriber->lock);
 281         }
 282         subscr_del(sub);
 283 }
 284
 285 /**
 286  * subscr_subscribe - create subscription for subscriber
 287  *
 288  * Called with subscriber port locked.
 289  */
 290 static struct tipc_subscription *subscr_subscribe(struct tipc_subscr *s,
 291                                              struct tipc_subscriber *subscriber)
 292 {
 293         struct tipc_subscription *sub;
 294         int swap;
 295
 296         /* Determine subscriber's endianness */
 297         swap = !(s->filter & (TIPC_SUB_PORTS | TIPC_SUB_SERVICE));
 298
 299         /* Detect & process a subscription cancellation request */
 300         if (s->filter & htohl(TIPC_SUB_CANCEL, swap)) {
 301                 s->filter &= ~htohl(TIPC_SUB_CANCEL, swap);
 302                 subscr_cancel(s, subscriber);
 303                 return NULL;
 304         }
 305
 306         /* Refuse subscription if global limit exceeded */
 307         if (atomic_read(&topsrv.subscription_count) >= TIPC_MAX_SUBSCRIPTIONS) {
 308                 pr_warn("Subscription rejected, limit reached (%u)\n",
 309                         TIPC_MAX_SUBSCRIPTIONS);
 310                 subscr_terminate(subscriber);
 311                 return NULL;
 312         }
 313
 314         /* Allocate subscription object */
 315         sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
 316         if (!sub) {
 317                 pr_warn("Subscription rejected, no memory\n");
 318                 subscr_terminate(subscriber);
 319                 return NULL;
 320         }
 321
 322         /* Initialize subscription object */
 323         sub->seq.type = htohl(s->seq.type, swap);
 324         sub->seq.lower = htohl(s->seq.lower, swap);
 325         sub->seq.upper = htohl(s->seq.upper, swap);
 326         sub->timeout = htohl(s->timeout, swap);
 327         sub->filter = htohl(s->filter, swap);
 328         if ((!(sub->filter & TIPC_SUB_PORTS) ==
 329              !(sub->filter & TIPC_SUB_SERVICE)) ||
 330             (sub->seq.lower > sub->seq.upper)) {
 331                 pr_warn("Subscription rejected, illegal request\n");
 332                 kfree(sub);
 333                 subscr_terminate(subscriber);
 334                 return NULL;
 335         }
 336         INIT_LIST_HEAD(&sub->nameseq_list);
 337         list_add(&sub->subscription_list, &subscriber->subscription_list);
 338         sub->server_ref = subscriber->port_ref;
 339         sub->swap = swap;
 340         memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
 341         atomic_inc(&topsrv.subscription_count);
 342         if (sub->timeout != TIPC_WAIT_FOREVER) {
 343                 k_init_timer(&sub->timer,
 344                              (Handler)subscr_timeout, (unsigned long)sub);
 345                 k_start_timer(&sub->timer, sub->timeout);
 346         }
 347
 348         return sub;
 349 }
 350
 351 /**
 352  * subscr_conn_shutdown_event - handle termination request from subscriber
 353  *
 354  * Called with subscriber's server port unlocked.
 355  */
 356 static void subscr_conn_shutdown_event(void *usr_handle,
 357                                        u32 port_ref,
 358                                        struct sk_buff **buf,
 359                                        unsigned char const *data,
 360                                        unsigned int size,
 361                                        int reason)
 362 {
 363         struct tipc_subscriber *subscriber = usr_handle;
 364         spinlock_t *subscriber_lock;
 365
 366         if (tipc_port_lock(port_ref) == NULL)
 367                 return;
 368
 369         subscriber_lock = subscriber->lock;
 370         subscr_terminate(subscriber);
 371         spin_unlock_bh(subscriber_lock);
 372 }
 373
 374 /**
 375  * subscr_conn_msg_event - handle new subscription request from subscriber
 376  *
 377  * Called with subscriber's server port unlocked.
 378  */
 379 static void subscr_conn_msg_event(void *usr_handle,
 380                                   u32 port_ref,
 381                                   struct sk_buff **buf,
 382                                   const unchar *data,
 383                                   u32 size)
 384 {
 385         struct tipc_subscriber *subscriber = usr_handle;
 386         spinlock_t *subscriber_lock;
 387         struct tipc_subscription *sub;
 388
 389         /*
 390          * Lock subscriber's server port (& make a local copy of lock pointer,
 391          * in case subscriber is deleted while processing subscription request)
 392          */
 393         if (tipc_port_lock(port_ref) == NULL)
 394                 return;
 395
 396         subscriber_lock = subscriber->lock;
 397
 398         if (size != sizeof(struct tipc_subscr)) {
 399                 subscr_terminate(subscriber);
 400                 spin_unlock_bh(subscriber_lock);
 401         } else {
 402                 sub = subscr_subscribe((struct tipc_subscr *)data, subscriber);
 403                 spin_unlock_bh(subscriber_lock);
 404                 if (sub != NULL) {
 405
 406                         /*
 407                          * We must release the server port lock before adding a
 408                          * subscription to the name table since TIPC needs to be
 409                          * able to (re)acquire the port lock if an event message
 410                          * issued by the subscription process is rejected and
 411                          * returned.  The subscription cannot be deleted while
 412                          * it is being added to the name table because:
 413                          * a) the single-threading of the native API port code
 414                          *    ensures the subscription cannot be cancelled and
 415                          *    the subscriber connection cannot be broken, and
 416                          * b) the name table lock ensures the subscription
 417                          *    timeout code cannot delete the subscription,
 418                          * so the subscription object is still protected.
 419                          */
 420                         tipc_nametbl_subscribe(sub);
 421                 }
 422         }
 423 }
 424
 425 /**
 426  * subscr_named_msg_event - handle request to establish a new subscriber
 427  */
 428 static void subscr_named_msg_event(void *usr_handle,
 429                                    u32 port_ref,
 430                                    struct sk_buff **buf,
 431                                    const unchar *data,
 432                                    u32 size,
 433                                    u32 importance,
 434                                    struct tipc_portid const *orig,
 435                                    struct tipc_name_seq const *dest)
 436 {
 437         struct tipc_subscriber *subscriber;
 438         u32 server_port_ref;
 439
 440         /* Create subscriber object */
 441         subscriber = kzalloc(sizeof(struct tipc_subscriber), GFP_ATOMIC);
 442         if (subscriber == NULL) {
 443                 pr_warn("Subscriber rejected, no memory\n");
 444                 return;
 445         }
 446         INIT_LIST_HEAD(&subscriber->subscription_list);
 447         INIT_LIST_HEAD(&subscriber->subscriber_list);
 448
 449         /* Create server port & establish connection to subscriber */
 450         tipc_createport(subscriber,
 451                         importance,
 452                         NULL,
 453                         NULL,
 454                         subscr_conn_shutdown_event,
 455                         NULL,
 456                         NULL,
 457                         subscr_conn_msg_event,
 458                         NULL,
 459                         &subscriber->port_ref);
 460         if (subscriber->port_ref == 0) {
 461                 pr_warn("Subscriber rejected, unable to create port\n");
 462                 kfree(subscriber);
 463                 return;
 464         }
 465         tipc_connect(subscriber->port_ref, orig);
 466
 467         /* Lock server port (& save lock address for future use) */
 468         subscriber->lock = tipc_port_lock(subscriber->port_ref)->lock;
 469
 470         /* Add subscriber to topology server's subscriber list */
 471         spin_lock_bh(&topsrv.lock);
 472         list_add(&subscriber->subscriber_list, &topsrv.subscriber_list);
 473         spin_unlock_bh(&topsrv.lock);
 474
 475         /* Unlock server port */
 476         server_port_ref = subscriber->port_ref;
 477         spin_unlock_bh(subscriber->lock);
 478
 479         /* Send an ACK- to complete connection handshaking */
 480         tipc_send(server_port_ref, 0, NULL, 0);
 481
 482         /* Handle optional subscription request */
 483         if (size != 0) {
 484                 subscr_conn_msg_event(subscriber, server_port_ref,
 485                                       buf, data, size);
 486         }
 487 }
 488
 489 int tipc_subscr_start(void)
 490 {
 491         struct tipc_name_seq seq = {TIPC_TOP_SRV, TIPC_TOP_SRV, TIPC_TOP_SRV};
 492         int res;
 493
 494         spin_lock_init(&topsrv.lock);
 495         INIT_LIST_HEAD(&topsrv.subscriber_list);
 496
 497         res = tipc_createport(NULL,
 498                               TIPC_CRITICAL_IMPORTANCE,
 499                               NULL,
 500                               NULL,
 501                               NULL,
 502                               NULL,
 503                               subscr_named_msg_event,
 504                               NULL,
 505                               NULL,
 506                               &topsrv.setup_port);
 507         if (res)
 508                 goto failed;
 509
 510         res = tipc_publish(topsrv.setup_port, TIPC_NODE_SCOPE, &seq);
 511         if (res) {
 512                 tipc_deleteport(topsrv.setup_port);
 513                 topsrv.setup_port = 0;
 514                 goto failed;
 515         }
 516
 517         return 0;
 518
 519 failed:
 520         pr_err("Failed to create subscription service\n");
 521         return res;
 522 }
 523
 524 void tipc_subscr_stop(void)
 525 {
 526         struct tipc_subscriber *subscriber;
 527         struct tipc_subscriber *subscriber_temp;
 528         spinlock_t *subscriber_lock;
 529
 530         if (topsrv.setup_port) {
 531                 tipc_deleteport(topsrv.setup_port);
 532                 topsrv.setup_port = 0;
 533
 534                 list_for_each_entry_safe(subscriber, subscriber_temp,
 535                                          &topsrv.subscriber_list,
 536                                          subscriber_list) {
 537                         subscriber_lock = subscriber->lock;
 538                         spin_lock_bh(subscriber_lock);
 539                         subscr_terminate(subscriber);
 540                         spin_unlock_bh(subscriber_lock);
 541                 }
 542         }
 543 }