linux/net/tipc/subscr.c
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   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 */
  49struct 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 */
  63struct top_srv {
  64        u32 setup_port;
  65        atomic_t subscription_count;
  66        struct list_head subscriber_list;
  67        spinlock_t lock;
  68};
  69
  70static 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 */
  79static 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 */
  90static 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 */
 115int 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 */
 134void 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 */
 153static 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 */
 192static 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 */
 210static 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 */
 256static 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 */
 290static 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 */
 356static 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 */
 379static 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 */
 428static 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_connect2port(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
 489int 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
 519failed:
 520        pr_err("Failed to create subscription service\n");
 521        return res;
 522}
 523
 524void 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}
 544
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