net/rxrpc/conn_client.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Client connection-specific management code.
   3  *
   4  * Copyright (C) 2016, 2020 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  *
   7  * Client connections need to be cached for a little while after they've made a
   8  * call so as to handle retransmitted DATA packets in case the server didn't
   9  * receive the final ACK or terminating ABORT we sent it.
  10  *
  11  * There are flags of relevance to the cache:
  12  *
  13  *  (2) DONT_REUSE - The connection should be discarded as soon as possible and
  14  *      should not be reused.  This is set when an exclusive connection is used
  15  *      or a call ID counter overflows.
  16  *
  17  * The caching state may only be changed if the cache lock is held.
  18  *
  19  * There are two idle client connection expiry durations.  If the total number
  20  * of connections is below the reap threshold, we use the normal duration; if
  21  * it's above, we use the fast duration.
  22  */
  23
  24 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  25
  26 #include <linux/slab.h>
  27 #include <linux/idr.h>
  28 #include <linux/timer.h>
  29 #include <linux/sched/signal.h>
  30
  31 #include "ar-internal.h"
  32
  33 __read_mostly unsigned int rxrpc_reap_client_connections = 900;
  34 __read_mostly unsigned long rxrpc_conn_idle_client_expiry = 2 * 60 * HZ;
  35 __read_mostly unsigned long rxrpc_conn_idle_client_fast_expiry = 2 * HZ;
  36
  37 /*
  38  * We use machine-unique IDs for our client connections.
  39  */
  40 DEFINE_IDR(rxrpc_client_conn_ids);
  41 static DEFINE_SPINLOCK(rxrpc_conn_id_lock);
  42
  43 static void rxrpc_deactivate_bundle(struct rxrpc_bundle *bundle);
  44
  45 /*
  46  * Get a connection ID and epoch for a client connection from the global pool.
  47  * The connection struct pointer is then recorded in the idr radix tree.  The
  48  * epoch doesn't change until the client is rebooted (or, at least, unless the
  49  * module is unloaded).
  50  */
  51 static int rxrpc_get_client_connection_id(struct rxrpc_connection *conn,
  52                                           gfp_t gfp)
  53 {
  54         struct rxrpc_net *rxnet = conn->local->rxnet;
  55         int id;
  56
  57         _enter("");
  58
  59         idr_preload(gfp);
  60         spin_lock(&rxrpc_conn_id_lock);
  61
  62         id = idr_alloc_cyclic(&rxrpc_client_conn_ids, conn,
  63                               1, 0x40000000, GFP_NOWAIT);
  64         if (id < 0)
  65                 goto error;
  66
  67         spin_unlock(&rxrpc_conn_id_lock);
  68         idr_preload_end();
  69
  70         conn->proto.epoch = rxnet->epoch;
  71         conn->proto.cid = id << RXRPC_CIDSHIFT;
  72         set_bit(RXRPC_CONN_HAS_IDR, &conn->flags);
  73         _leave(" [CID %x]", conn->proto.cid);
  74         return 0;
  75
  76 error:
  77         spin_unlock(&rxrpc_conn_id_lock);
  78         idr_preload_end();
  79         _leave(" = %d", id);
  80         return id;
  81 }
  82
  83 /*
  84  * Release a connection ID for a client connection from the global pool.
  85  */
  86 static void rxrpc_put_client_connection_id(struct rxrpc_connection *conn)
  87 {
  88         if (test_bit(RXRPC_CONN_HAS_IDR, &conn->flags)) {
  89                 spin_lock(&rxrpc_conn_id_lock);
  90                 idr_remove(&rxrpc_client_conn_ids,
  91                            conn->proto.cid >> RXRPC_CIDSHIFT);
  92                 spin_unlock(&rxrpc_conn_id_lock);
  93         }
  94 }
  95
  96 /*
  97  * Destroy the client connection ID tree.
  98  */
  99 void rxrpc_destroy_client_conn_ids(void)
 100 {
 101         struct rxrpc_connection *conn;
 102         int id;
 103
 104         if (!idr_is_empty(&rxrpc_client_conn_ids)) {
 105                 idr_for_each_entry(&rxrpc_client_conn_ids, conn, id) {
 106                         pr_err("AF_RXRPC: Leaked client conn %p {%d}\n",
 107                                conn, refcount_read(&conn->ref));
 108                 }
 109                 BUG();
 110         }
 111
 112         idr_destroy(&rxrpc_client_conn_ids);
 113 }
 114
 115 /*
 116  * Allocate a connection bundle.
 117  */
 118 static struct rxrpc_bundle *rxrpc_alloc_bundle(struct rxrpc_conn_parameters *cp,
 119                                                gfp_t gfp)
 120 {
 121         struct rxrpc_bundle *bundle;
 122
 123         bundle = kzalloc(sizeof(*bundle), gfp);
 124         if (bundle) {
 125                 bundle->local           = cp->local;
 126                 bundle->peer            = rxrpc_get_peer(cp->peer, rxrpc_peer_get_bundle);
 127                 bundle->key             = cp->key;
 128                 bundle->exclusive       = cp->exclusive;
 129                 bundle->upgrade         = cp->upgrade;
 130                 bundle->service_id      = cp->service_id;
 131                 bundle->security_level  = cp->security_level;
 132                 refcount_set(&bundle->ref, 1);
 133                 atomic_set(&bundle->active, 1);
 134                 spin_lock_init(&bundle->channel_lock);
 135                 INIT_LIST_HEAD(&bundle->waiting_calls);
 136         }
 137         return bundle;
 138 }
 139
 140 struct rxrpc_bundle *rxrpc_get_bundle(struct rxrpc_bundle *bundle)
 141 {
 142         refcount_inc(&bundle->ref);
 143         return bundle;
 144 }
 145
 146 static void rxrpc_free_bundle(struct rxrpc_bundle *bundle)
 147 {
 148         rxrpc_put_peer(bundle->peer, rxrpc_peer_put_bundle);
 149         kfree(bundle);
 150 }
 151
 152 void rxrpc_put_bundle(struct rxrpc_bundle *bundle)
 153 {
 154         unsigned int d = bundle->debug_id;
 155         bool dead;
 156         int r;
 157
 158         dead = __refcount_dec_and_test(&bundle->ref, &r);
 159
 160         _debug("PUT B=%x %d", d, r - 1);
 161         if (dead)
 162                 rxrpc_free_bundle(bundle);
 163 }
 164
 165 /*
 166  * Allocate a client connection.
 167  */
 168 static struct rxrpc_connection *
 169 rxrpc_alloc_client_connection(struct rxrpc_bundle *bundle, gfp_t gfp)
 170 {
 171         struct rxrpc_connection *conn;
 172         struct rxrpc_net *rxnet = bundle->local->rxnet;
 173         int ret;
 174
 175         _enter("");
 176
 177         conn = rxrpc_alloc_connection(gfp);
 178         if (!conn) {
 179                 _leave(" = -ENOMEM");
 180                 return ERR_PTR(-ENOMEM);
 181         }
 182
 183         refcount_set(&conn->ref, 1);
 184         conn->bundle            = bundle;
 185         conn->local             = bundle->local;
 186         conn->peer              = bundle->peer;
 187         conn->key               = bundle->key;
 188         conn->exclusive         = bundle->exclusive;
 189         conn->upgrade           = bundle->upgrade;
 190         conn->orig_service_id   = bundle->service_id;
 191         conn->security_level    = bundle->security_level;
 192         conn->out_clientflag    = RXRPC_CLIENT_INITIATED;
 193         conn->state             = RXRPC_CONN_CLIENT;
 194         conn->service_id        = conn->orig_service_id;
 195
 196         ret = rxrpc_get_client_connection_id(conn, gfp);
 197         if (ret < 0)
 198                 goto error_0;
 199
 200         ret = rxrpc_init_client_conn_security(conn);
 201         if (ret < 0)
 202                 goto error_1;
 203
 204         atomic_inc(&rxnet->nr_conns);
 205         write_lock(&rxnet->conn_lock);
 206         list_add_tail(&conn->proc_link, &rxnet->conn_proc_list);
 207         write_unlock(&rxnet->conn_lock);
 208
 209         rxrpc_get_bundle(bundle);
 210         rxrpc_get_peer(conn->peer, rxrpc_peer_get_client_conn);
 211         rxrpc_get_local(conn->local, rxrpc_local_get_client_conn);
 212         key_get(conn->key);
 213
 214         trace_rxrpc_conn(conn->debug_id, rxrpc_conn_new_client,
 215                          refcount_read(&conn->ref),
 216                          __builtin_return_address(0));
 217
 218         atomic_inc(&rxnet->nr_client_conns);
 219         trace_rxrpc_client(conn, -1, rxrpc_client_alloc);
 220         _leave(" = %p", conn);
 221         return conn;
 222
 223 error_1:
 224         rxrpc_put_client_connection_id(conn);
 225 error_0:
 226         kfree(conn);
 227         _leave(" = %d", ret);
 228         return ERR_PTR(ret);
 229 }
 230
 231 /*
 232  * Determine if a connection may be reused.
 233  */
 234 static bool rxrpc_may_reuse_conn(struct rxrpc_connection *conn)
 235 {
 236         struct rxrpc_net *rxnet;
 237         int id_cursor, id, distance, limit;
 238
 239         if (!conn)
 240                 goto dont_reuse;
 241
 242         rxnet = conn->local->rxnet;
 243         if (test_bit(RXRPC_CONN_DONT_REUSE, &conn->flags))
 244                 goto dont_reuse;
 245
 246         if (conn->state != RXRPC_CONN_CLIENT ||
 247             conn->proto.epoch != rxnet->epoch)
 248                 goto mark_dont_reuse;
 249
 250         /* The IDR tree gets very expensive on memory if the connection IDs are
 251          * widely scattered throughout the number space, so we shall want to
 252          * kill off connections that, say, have an ID more than about four
 253          * times the maximum number of client conns away from the current
 254          * allocation point to try and keep the IDs concentrated.
 255          */
 256         id_cursor = idr_get_cursor(&rxrpc_client_conn_ids);
 257         id = conn->proto.cid >> RXRPC_CIDSHIFT;
 258         distance = id - id_cursor;
 259         if (distance < 0)
 260                 distance = -distance;
 261         limit = max_t(unsigned long, atomic_read(&rxnet->nr_conns) * 4, 1024);
 262         if (distance > limit)
 263                 goto mark_dont_reuse;
 264
 265         return true;
 266
 267 mark_dont_reuse:
 268         set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
 269 dont_reuse:
 270         return false;
 271 }
 272
 273 /*
 274  * Look up the conn bundle that matches the connection parameters, adding it if
 275  * it doesn't yet exist.
 276  */
 277 static struct rxrpc_bundle *rxrpc_look_up_bundle(struct rxrpc_conn_parameters *cp,
 278                                                  gfp_t gfp)
 279 {
 280         static atomic_t rxrpc_bundle_id;
 281         struct rxrpc_bundle *bundle, *candidate;
 282         struct rxrpc_local *local = cp->local;
 283         struct rb_node *p, **pp, *parent;
 284         long diff;
 285
 286         _enter("{%px,%x,%u,%u}",
 287                cp->peer, key_serial(cp->key), cp->security_level, cp->upgrade);
 288
 289         if (cp->exclusive)
 290                 return rxrpc_alloc_bundle(cp, gfp);
 291
 292         /* First, see if the bundle is already there. */
 293         _debug("search 1");
 294         spin_lock(&local->client_bundles_lock);
 295         p = local->client_bundles.rb_node;
 296         while (p) {
 297                 bundle = rb_entry(p, struct rxrpc_bundle, local_node);
 298
 299 #define cmp(X) ((long)bundle->X - (long)cp->X)
 300                 diff = (cmp(peer) ?:
 301                         cmp(key) ?:
 302                         cmp(security_level) ?:
 303                         cmp(upgrade));
 304 #undef cmp
 305                 if (diff < 0)
 306                         p = p->rb_left;
 307                 else if (diff > 0)
 308                         p = p->rb_right;
 309                 else
 310                         goto found_bundle;
 311         }
 312         spin_unlock(&local->client_bundles_lock);
 313         _debug("not found");
 314
 315         /* It wasn't.  We need to add one. */
 316         candidate = rxrpc_alloc_bundle(cp, gfp);
 317         if (!candidate)
 318                 return NULL;
 319
 320         _debug("search 2");
 321         spin_lock(&local->client_bundles_lock);
 322         pp = &local->client_bundles.rb_node;
 323         parent = NULL;
 324         while (*pp) {
 325                 parent = *pp;
 326                 bundle = rb_entry(parent, struct rxrpc_bundle, local_node);
 327
 328 #define cmp(X) ((long)bundle->X - (long)cp->X)
 329                 diff = (cmp(peer) ?:
 330                         cmp(key) ?:
 331                         cmp(security_level) ?:
 332                         cmp(upgrade));
 333 #undef cmp
 334                 if (diff < 0)
 335                         pp = &(*pp)->rb_left;
 336                 else if (diff > 0)
 337                         pp = &(*pp)->rb_right;
 338                 else
 339                         goto found_bundle_free;
 340         }
 341
 342         _debug("new bundle");
 343         candidate->debug_id = atomic_inc_return(&rxrpc_bundle_id);
 344         rb_link_node(&candidate->local_node, parent, pp);
 345         rb_insert_color(&candidate->local_node, &local->client_bundles);
 346         rxrpc_get_bundle(candidate);
 347         spin_unlock(&local->client_bundles_lock);
 348         _leave(" = %u [new]", candidate->debug_id);
 349         return candidate;
 350
 351 found_bundle_free:
 352         rxrpc_free_bundle(candidate);
 353 found_bundle:
 354         rxrpc_get_bundle(bundle);
 355         atomic_inc(&bundle->active);
 356         spin_unlock(&local->client_bundles_lock);
 357         _leave(" = %u [found]", bundle->debug_id);
 358         return bundle;
 359 }
 360
 361 /*
 362  * Create or find a client bundle to use for a call.
 363  *
 364  * If we return with a connection, the call will be on its waiting list.  It's
 365  * left to the caller to assign a channel and wake up the call.
 366  */
 367 static struct rxrpc_bundle *rxrpc_prep_call(struct rxrpc_sock *rx,
 368                                             struct rxrpc_call *call,
 369                                             struct rxrpc_conn_parameters *cp,
 370                                             struct sockaddr_rxrpc *srx,
 371                                             gfp_t gfp)
 372 {
 373         struct rxrpc_bundle *bundle;
 374
 375         _enter("{%d,%lx},", call->debug_id, call->user_call_ID);
 376
 377         cp->peer = rxrpc_lookup_peer(rx, cp->local, srx, gfp);
 378         if (!cp->peer)
 379                 goto error;
 380
 381         call->tx_last_sent = ktime_get_real();
 382         call->cong_ssthresh = cp->peer->cong_ssthresh;
 383         if (call->cong_cwnd >= call->cong_ssthresh)
 384                 call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
 385         else
 386                 call->cong_mode = RXRPC_CALL_SLOW_START;
 387         if (cp->upgrade)
 388                 __set_bit(RXRPC_CALL_UPGRADE, &call->flags);
 389
 390         /* Find the client connection bundle. */
 391         bundle = rxrpc_look_up_bundle(cp, gfp);
 392         if (!bundle)
 393                 goto error;
 394
 395         /* Get this call queued.  Someone else may activate it whilst we're
 396          * lining up a new connection, but that's fine.
 397          */
 398         spin_lock(&bundle->channel_lock);
 399         list_add_tail(&call->chan_wait_link, &bundle->waiting_calls);
 400         spin_unlock(&bundle->channel_lock);
 401
 402         _leave(" = [B=%x]", bundle->debug_id);
 403         return bundle;
 404
 405 error:
 406         _leave(" = -ENOMEM");
 407         return ERR_PTR(-ENOMEM);
 408 }
 409
 410 /*
 411  * Allocate a new connection and add it into a bundle.
 412  */
 413 static void rxrpc_add_conn_to_bundle(struct rxrpc_bundle *bundle, gfp_t gfp)
 414         __releases(bundle->channel_lock)
 415 {
 416         struct rxrpc_connection *candidate = NULL, *old = NULL;
 417         bool conflict;
 418         int i;
 419
 420         _enter("");
 421
 422         conflict = bundle->alloc_conn;
 423         if (!conflict)
 424                 bundle->alloc_conn = true;
 425         spin_unlock(&bundle->channel_lock);
 426         if (conflict) {
 427                 _leave(" [conf]");
 428                 return;
 429         }
 430
 431         candidate = rxrpc_alloc_client_connection(bundle, gfp);
 432
 433         spin_lock(&bundle->channel_lock);
 434         bundle->alloc_conn = false;
 435
 436         if (IS_ERR(candidate)) {
 437                 bundle->alloc_error = PTR_ERR(candidate);
 438                 spin_unlock(&bundle->channel_lock);
 439                 _leave(" [err %ld]", PTR_ERR(candidate));
 440                 return;
 441         }
 442
 443         bundle->alloc_error = 0;
 444
 445         for (i = 0; i < ARRAY_SIZE(bundle->conns); i++) {
 446                 unsigned int shift = i * RXRPC_MAXCALLS;
 447                 int j;
 448
 449                 old = bundle->conns[i];
 450                 if (!rxrpc_may_reuse_conn(old)) {
 451                         if (old)
 452                                 trace_rxrpc_client(old, -1, rxrpc_client_replace);
 453                         candidate->bundle_shift = shift;
 454                         atomic_inc(&bundle->active);
 455                         bundle->conns[i] = candidate;
 456                         for (j = 0; j < RXRPC_MAXCALLS; j++)
 457                                 set_bit(shift + j, &bundle->avail_chans);
 458                         candidate = NULL;
 459                         break;
 460                 }
 461
 462                 old = NULL;
 463         }
 464
 465         spin_unlock(&bundle->channel_lock);
 466
 467         if (candidate) {
 468                 _debug("discard C=%x", candidate->debug_id);
 469                 trace_rxrpc_client(candidate, -1, rxrpc_client_duplicate);
 470                 rxrpc_put_connection(candidate);
 471         }
 472
 473         rxrpc_put_connection(old);
 474         _leave("");
 475 }
 476
 477 /*
 478  * Add a connection to a bundle if there are no usable connections or we have
 479  * connections waiting for extra capacity.
 480  */
 481 static void rxrpc_maybe_add_conn(struct rxrpc_bundle *bundle, gfp_t gfp)
 482 {
 483         struct rxrpc_call *call;
 484         int i, usable;
 485
 486         _enter("");
 487
 488         spin_lock(&bundle->channel_lock);
 489
 490         /* See if there are any usable connections. */
 491         usable = 0;
 492         for (i = 0; i < ARRAY_SIZE(bundle->conns); i++)
 493                 if (rxrpc_may_reuse_conn(bundle->conns[i]))
 494                         usable++;
 495
 496         if (!usable && !list_empty(&bundle->waiting_calls)) {
 497                 call = list_first_entry(&bundle->waiting_calls,
 498                                         struct rxrpc_call, chan_wait_link);
 499                 if (test_bit(RXRPC_CALL_UPGRADE, &call->flags))
 500                         bundle->try_upgrade = true;
 501         }
 502
 503         if (!usable)
 504                 goto alloc_conn;
 505
 506         if (!bundle->avail_chans &&
 507             !bundle->try_upgrade &&
 508             !list_empty(&bundle->waiting_calls) &&
 509             usable < ARRAY_SIZE(bundle->conns))
 510                 goto alloc_conn;
 511
 512         spin_unlock(&bundle->channel_lock);
 513         _leave("");
 514         return;
 515
 516 alloc_conn:
 517         return rxrpc_add_conn_to_bundle(bundle, gfp);
 518 }
 519
 520 /*
 521  * Assign a channel to the call at the front of the queue and wake the call up.
 522  * We don't increment the callNumber counter until this number has been exposed
 523  * to the world.
 524  */
 525 static void rxrpc_activate_one_channel(struct rxrpc_connection *conn,
 526                                        unsigned int channel)
 527 {
 528         struct rxrpc_channel *chan = &conn->channels[channel];
 529         struct rxrpc_bundle *bundle = conn->bundle;
 530         struct rxrpc_call *call = list_entry(bundle->waiting_calls.next,
 531                                              struct rxrpc_call, chan_wait_link);
 532         u32 call_id = chan->call_counter + 1;
 533
 534         _enter("C=%x,%u", conn->debug_id, channel);
 535
 536         trace_rxrpc_client(conn, channel, rxrpc_client_chan_activate);
 537
 538         /* Cancel the final ACK on the previous call if it hasn't been sent yet
 539          * as the DATA packet will implicitly ACK it.
 540          */
 541         clear_bit(RXRPC_CONN_FINAL_ACK_0 + channel, &conn->flags);
 542         clear_bit(conn->bundle_shift + channel, &bundle->avail_chans);
 543
 544         rxrpc_see_call(call);
 545         list_del_init(&call->chan_wait_link);
 546         call->peer      = rxrpc_get_peer(conn->peer, rxrpc_peer_get_activate_call);
 547         call->conn      = rxrpc_get_connection(conn);
 548         call->cid       = conn->proto.cid | channel;
 549         call->call_id   = call_id;
 550         call->security  = conn->security;
 551         call->security_ix = conn->security_ix;
 552         call->service_id = conn->service_id;
 553
 554         trace_rxrpc_connect_call(call);
 555
 556         write_lock_bh(&call->state_lock);
 557         call->state = RXRPC_CALL_CLIENT_SEND_REQUEST;
 558         write_unlock_bh(&call->state_lock);
 559
 560         /* Paired with the read barrier in rxrpc_connect_call().  This orders
 561          * cid and epoch in the connection wrt to call_id without the need to
 562          * take the channel_lock.
 563          *
 564          * We provisionally assign a callNumber at this point, but we don't
 565          * confirm it until the call is about to be exposed.
 566          *
 567          * TODO: Pair with a barrier in the data_ready handler when that looks
 568          * at the call ID through a connection channel.
 569          */
 570         smp_wmb();
 571
 572         chan->call_id           = call_id;
 573         chan->call_debug_id     = call->debug_id;
 574         rcu_assign_pointer(chan->call, call);
 575         wake_up(&call->waitq);
 576 }
 577
 578 /*
 579  * Remove a connection from the idle list if it's on it.
 580  */
 581 static void rxrpc_unidle_conn(struct rxrpc_bundle *bundle, struct rxrpc_connection *conn)
 582 {
 583         struct rxrpc_net *rxnet = bundle->local->rxnet;
 584         bool drop_ref;
 585
 586         if (!list_empty(&conn->cache_link)) {
 587                 drop_ref = false;
 588                 spin_lock(&rxnet->client_conn_cache_lock);
 589                 if (!list_empty(&conn->cache_link)) {
 590                         list_del_init(&conn->cache_link);
 591                         drop_ref = true;
 592                 }
 593                 spin_unlock(&rxnet->client_conn_cache_lock);
 594                 if (drop_ref)
 595                         rxrpc_put_connection(conn);
 596         }
 597 }
 598
 599 /*
 600  * Assign channels and callNumbers to waiting calls with channel_lock
 601  * held by caller.
 602  */
 603 static void rxrpc_activate_channels_locked(struct rxrpc_bundle *bundle)
 604 {
 605         struct rxrpc_connection *conn;
 606         unsigned long avail, mask;
 607         unsigned int channel, slot;
 608
 609         if (bundle->try_upgrade)
 610                 mask = 1;
 611         else
 612                 mask = ULONG_MAX;
 613
 614         while (!list_empty(&bundle->waiting_calls)) {
 615                 avail = bundle->avail_chans & mask;
 616                 if (!avail)
 617                         break;
 618                 channel = __ffs(avail);
 619                 clear_bit(channel, &bundle->avail_chans);
 620
 621                 slot = channel / RXRPC_MAXCALLS;
 622                 conn = bundle->conns[slot];
 623                 if (!conn)
 624                         break;
 625
 626                 if (bundle->try_upgrade)
 627                         set_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags);
 628                 rxrpc_unidle_conn(bundle, conn);
 629
 630                 channel &= (RXRPC_MAXCALLS - 1);
 631                 conn->act_chans |= 1 << channel;
 632                 rxrpc_activate_one_channel(conn, channel);
 633         }
 634 }
 635
 636 /*
 637  * Assign channels and callNumbers to waiting calls.
 638  */
 639 static void rxrpc_activate_channels(struct rxrpc_bundle *bundle)
 640 {
 641         _enter("B=%x", bundle->debug_id);
 642
 643         trace_rxrpc_client(NULL, -1, rxrpc_client_activate_chans);
 644
 645         if (!bundle->avail_chans)
 646                 return;
 647
 648         spin_lock(&bundle->channel_lock);
 649         rxrpc_activate_channels_locked(bundle);
 650         spin_unlock(&bundle->channel_lock);
 651         _leave("");
 652 }
 653
 654 /*
 655  * Wait for a callNumber and a channel to be granted to a call.
 656  */
 657 static int rxrpc_wait_for_channel(struct rxrpc_bundle *bundle,
 658                                   struct rxrpc_call *call, gfp_t gfp)
 659 {
 660         DECLARE_WAITQUEUE(myself, current);
 661         int ret = 0;
 662
 663         _enter("%d", call->debug_id);
 664
 665         if (!gfpflags_allow_blocking(gfp)) {
 666                 rxrpc_maybe_add_conn(bundle, gfp);
 667                 rxrpc_activate_channels(bundle);
 668                 ret = bundle->alloc_error ?: -EAGAIN;
 669                 goto out;
 670         }
 671
 672         add_wait_queue_exclusive(&call->waitq, &myself);
 673         for (;;) {
 674                 rxrpc_maybe_add_conn(bundle, gfp);
 675                 rxrpc_activate_channels(bundle);
 676                 ret = bundle->alloc_error;
 677                 if (ret < 0)
 678                         break;
 679
 680                 switch (call->interruptibility) {
 681                 case RXRPC_INTERRUPTIBLE:
 682                 case RXRPC_PREINTERRUPTIBLE:
 683                         set_current_state(TASK_INTERRUPTIBLE);
 684                         break;
 685                 case RXRPC_UNINTERRUPTIBLE:
 686                 default:
 687                         set_current_state(TASK_UNINTERRUPTIBLE);
 688                         break;
 689                 }
 690                 if (READ_ONCE(call->state) != RXRPC_CALL_CLIENT_AWAIT_CONN)
 691                         break;
 692                 if ((call->interruptibility == RXRPC_INTERRUPTIBLE ||
 693                      call->interruptibility == RXRPC_PREINTERRUPTIBLE) &&
 694                     signal_pending(current)) {
 695                         ret = -ERESTARTSYS;
 696                         break;
 697                 }
 698                 schedule();
 699         }
 700         remove_wait_queue(&call->waitq, &myself);
 701         __set_current_state(TASK_RUNNING);
 702
 703 out:
 704         _leave(" = %d", ret);
 705         return ret;
 706 }
 707
 708 /*
 709  * find a connection for a call
 710  * - called in process context with IRQs enabled
 711  */
 712 int rxrpc_connect_call(struct rxrpc_sock *rx,
 713                        struct rxrpc_call *call,
 714                        struct rxrpc_conn_parameters *cp,
 715                        struct sockaddr_rxrpc *srx,
 716                        gfp_t gfp)
 717 {
 718         struct rxrpc_bundle *bundle;
 719         struct rxrpc_net *rxnet = cp->local->rxnet;
 720         int ret = 0;
 721
 722         _enter("{%d,%lx},", call->debug_id, call->user_call_ID);
 723
 724         rxrpc_discard_expired_client_conns(&rxnet->client_conn_reaper);
 725
 726         bundle = rxrpc_prep_call(rx, call, cp, srx, gfp);
 727         if (IS_ERR(bundle)) {
 728                 ret = PTR_ERR(bundle);
 729                 goto out;
 730         }
 731
 732         if (call->state == RXRPC_CALL_CLIENT_AWAIT_CONN) {
 733                 ret = rxrpc_wait_for_channel(bundle, call, gfp);
 734                 if (ret < 0)
 735                         goto wait_failed;
 736         }
 737
 738 granted_channel:
 739         /* Paired with the write barrier in rxrpc_activate_one_channel(). */
 740         smp_rmb();
 741
 742 out_put_bundle:
 743         rxrpc_deactivate_bundle(bundle);
 744         rxrpc_put_bundle(bundle);
 745 out:
 746         _leave(" = %d", ret);
 747         return ret;
 748
 749 wait_failed:
 750         spin_lock(&bundle->channel_lock);
 751         list_del_init(&call->chan_wait_link);
 752         spin_unlock(&bundle->channel_lock);
 753
 754         if (call->state != RXRPC_CALL_CLIENT_AWAIT_CONN) {
 755                 ret = 0;
 756                 goto granted_channel;
 757         }
 758
 759         trace_rxrpc_client(call->conn, ret, rxrpc_client_chan_wait_failed);
 760         rxrpc_set_call_completion(call, RXRPC_CALL_LOCAL_ERROR, 0, ret);
 761         rxrpc_disconnect_client_call(bundle, call);
 762         goto out_put_bundle;
 763 }
 764
 765 /*
 766  * Note that a call, and thus a connection, is about to be exposed to the
 767  * world.
 768  */
 769 void rxrpc_expose_client_call(struct rxrpc_call *call)
 770 {
 771         unsigned int channel = call->cid & RXRPC_CHANNELMASK;
 772         struct rxrpc_connection *conn = call->conn;
 773         struct rxrpc_channel *chan = &conn->channels[channel];
 774
 775         if (!test_and_set_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 776                 /* Mark the call ID as being used.  If the callNumber counter
 777                  * exceeds ~2 billion, we kill the connection after its
 778                  * outstanding calls have finished so that the counter doesn't
 779                  * wrap.
 780                  */
 781                 chan->call_counter++;
 782                 if (chan->call_counter >= INT_MAX)
 783                         set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
 784                 trace_rxrpc_client(conn, channel, rxrpc_client_exposed);
 785         }
 786 }
 787
 788 /*
 789  * Set the reap timer.
 790  */
 791 static void rxrpc_set_client_reap_timer(struct rxrpc_net *rxnet)
 792 {
 793         if (!rxnet->kill_all_client_conns) {
 794                 unsigned long now = jiffies;
 795                 unsigned long reap_at = now + rxrpc_conn_idle_client_expiry;
 796
 797                 if (rxnet->live)
 798                         timer_reduce(&rxnet->client_conn_reap_timer, reap_at);
 799         }
 800 }
 801
 802 /*
 803  * Disconnect a client call.
 804  */
 805 void rxrpc_disconnect_client_call(struct rxrpc_bundle *bundle, struct rxrpc_call *call)
 806 {
 807         struct rxrpc_connection *conn;
 808         struct rxrpc_channel *chan = NULL;
 809         struct rxrpc_net *rxnet = bundle->local->rxnet;
 810         unsigned int channel;
 811         bool may_reuse;
 812         u32 cid;
 813
 814         _enter("c=%x", call->debug_id);
 815
 816         spin_lock(&bundle->channel_lock);
 817         set_bit(RXRPC_CALL_DISCONNECTED, &call->flags);
 818
 819         /* Calls that have never actually been assigned a channel can simply be
 820          * discarded.
 821          */
 822         conn = call->conn;
 823         if (!conn) {
 824                 _debug("call is waiting");
 825                 ASSERTCMP(call->call_id, ==, 0);
 826                 ASSERT(!test_bit(RXRPC_CALL_EXPOSED, &call->flags));
 827                 list_del_init(&call->chan_wait_link);
 828                 goto out;
 829         }
 830
 831         cid = call->cid;
 832         channel = cid & RXRPC_CHANNELMASK;
 833         chan = &conn->channels[channel];
 834         trace_rxrpc_client(conn, channel, rxrpc_client_chan_disconnect);
 835
 836         if (rcu_access_pointer(chan->call) != call) {
 837                 spin_unlock(&bundle->channel_lock);
 838                 BUG();
 839         }
 840
 841         may_reuse = rxrpc_may_reuse_conn(conn);
 842
 843         /* If a client call was exposed to the world, we save the result for
 844          * retransmission.
 845          *
 846          * We use a barrier here so that the call number and abort code can be
 847          * read without needing to take a lock.
 848          *
 849          * TODO: Make the incoming packet handler check this and handle
 850          * terminal retransmission without requiring access to the call.
 851          */
 852         if (test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 853                 _debug("exposed %u,%u", call->call_id, call->abort_code);
 854                 __rxrpc_disconnect_call(conn, call);
 855
 856                 if (test_and_clear_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags)) {
 857                         trace_rxrpc_client(conn, channel, rxrpc_client_to_active);
 858                         bundle->try_upgrade = false;
 859                         if (may_reuse)
 860                                 rxrpc_activate_channels_locked(bundle);
 861                 }
 862
 863         }
 864
 865         /* See if we can pass the channel directly to another call. */
 866         if (may_reuse && !list_empty(&bundle->waiting_calls)) {
 867                 trace_rxrpc_client(conn, channel, rxrpc_client_chan_pass);
 868                 rxrpc_activate_one_channel(conn, channel);
 869                 goto out;
 870         }
 871
 872         /* Schedule the final ACK to be transmitted in a short while so that it
 873          * can be skipped if we find a follow-on call.  The first DATA packet
 874          * of the follow on call will implicitly ACK this call.
 875          */
 876         if (call->completion == RXRPC_CALL_SUCCEEDED &&
 877             test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 878                 unsigned long final_ack_at = jiffies + 2;
 879
 880                 WRITE_ONCE(chan->final_ack_at, final_ack_at);
 881                 smp_wmb(); /* vs rxrpc_process_delayed_final_acks() */
 882                 set_bit(RXRPC_CONN_FINAL_ACK_0 + channel, &conn->flags);
 883                 rxrpc_reduce_conn_timer(conn, final_ack_at);
 884         }
 885
 886         /* Deactivate the channel. */
 887         rcu_assign_pointer(chan->call, NULL);
 888         set_bit(conn->bundle_shift + channel, &conn->bundle->avail_chans);
 889         conn->act_chans &= ~(1 << channel);
 890
 891         /* If no channels remain active, then put the connection on the idle
 892          * list for a short while.  Give it a ref to stop it going away if it
 893          * becomes unbundled.
 894          */
 895         if (!conn->act_chans) {
 896                 trace_rxrpc_client(conn, channel, rxrpc_client_to_idle);
 897                 conn->idle_timestamp = jiffies;
 898
 899                 rxrpc_get_connection(conn);
 900                 spin_lock(&rxnet->client_conn_cache_lock);
 901                 list_move_tail(&conn->cache_link, &rxnet->idle_client_conns);
 902                 spin_unlock(&rxnet->client_conn_cache_lock);
 903
 904                 rxrpc_set_client_reap_timer(rxnet);
 905         }
 906
 907 out:
 908         spin_unlock(&bundle->channel_lock);
 909         _leave("");
 910         return;
 911 }
 912
 913 /*
 914  * Remove a connection from a bundle.
 915  */
 916 static void rxrpc_unbundle_conn(struct rxrpc_connection *conn)
 917 {
 918         struct rxrpc_bundle *bundle = conn->bundle;
 919         unsigned int bindex;
 920         bool need_drop = false;
 921         int i;
 922
 923         _enter("C=%x", conn->debug_id);
 924
 925         if (conn->flags & RXRPC_CONN_FINAL_ACK_MASK)
 926                 rxrpc_process_delayed_final_acks(conn, true);
 927
 928         spin_lock(&bundle->channel_lock);
 929         bindex = conn->bundle_shift / RXRPC_MAXCALLS;
 930         if (bundle->conns[bindex] == conn) {
 931                 _debug("clear slot %u", bindex);
 932                 bundle->conns[bindex] = NULL;
 933                 for (i = 0; i < RXRPC_MAXCALLS; i++)
 934                         clear_bit(conn->bundle_shift + i, &bundle->avail_chans);
 935                 need_drop = true;
 936         }
 937         spin_unlock(&bundle->channel_lock);
 938
 939         if (need_drop) {
 940                 rxrpc_deactivate_bundle(bundle);
 941                 rxrpc_put_connection(conn);
 942         }
 943 }
 944
 945 /*
 946  * Drop the active count on a bundle.
 947  */
 948 static void rxrpc_deactivate_bundle(struct rxrpc_bundle *bundle)
 949 {
 950         struct rxrpc_local *local = bundle->local;
 951         bool need_put = false;
 952
 953         if (atomic_dec_and_lock(&bundle->active, &local->client_bundles_lock)) {
 954                 if (!bundle->exclusive) {
 955                         _debug("erase bundle");
 956                         rb_erase(&bundle->local_node, &local->client_bundles);
 957                         need_put = true;
 958                 }
 959
 960                 spin_unlock(&local->client_bundles_lock);
 961                 if (need_put)
 962                         rxrpc_put_bundle(bundle);
 963         }
 964 }
 965
 966 /*
 967  * Clean up a dead client connection.
 968  */
 969 static void rxrpc_kill_client_conn(struct rxrpc_connection *conn)
 970 {
 971         struct rxrpc_local *local = conn->local;
 972         struct rxrpc_net *rxnet = local->rxnet;
 973
 974         _enter("C=%x", conn->debug_id);
 975
 976         trace_rxrpc_client(conn, -1, rxrpc_client_cleanup);
 977         atomic_dec(&rxnet->nr_client_conns);
 978
 979         rxrpc_put_client_connection_id(conn);
 980         rxrpc_kill_connection(conn);
 981 }
 982
 983 /*
 984  * Clean up a dead client connections.
 985  */
 986 void rxrpc_put_client_conn(struct rxrpc_connection *conn)
 987 {
 988         const void *here = __builtin_return_address(0);
 989         unsigned int debug_id = conn->debug_id;
 990         bool dead;
 991         int r;
 992
 993         dead = __refcount_dec_and_test(&conn->ref, &r);
 994         trace_rxrpc_conn(debug_id, rxrpc_conn_put_client, r - 1, here);
 995         if (dead)
 996                 rxrpc_kill_client_conn(conn);
 997 }
 998
 999 /*
1000  * Discard expired client connections from the idle list.  Each conn in the
1001  * idle list has been exposed and holds an extra ref because of that.
1002  *
1003  * This may be called from conn setup or from a work item so cannot be
1004  * considered non-reentrant.
1005  */
1006 void rxrpc_discard_expired_client_conns(struct work_struct *work)
1007 {
1008         struct rxrpc_connection *conn;
1009         struct rxrpc_net *rxnet =
1010                 container_of(work, struct rxrpc_net, client_conn_reaper);
1011         unsigned long expiry, conn_expires_at, now;
1012         unsigned int nr_conns;
1013
1014         _enter("");
1015
1016         if (list_empty(&rxnet->idle_client_conns)) {
1017                 _leave(" [empty]");
1018                 return;
1019         }
1020
1021         /* Don't double up on the discarding */
1022         if (!spin_trylock(&rxnet->client_conn_discard_lock)) {
1023                 _leave(" [already]");
1024                 return;
1025         }
1026
1027         /* We keep an estimate of what the number of conns ought to be after
1028          * we've discarded some so that we don't overdo the discarding.
1029          */
1030         nr_conns = atomic_read(&rxnet->nr_client_conns);
1031
1032 next:
1033         spin_lock(&rxnet->client_conn_cache_lock);
1034
1035         if (list_empty(&rxnet->idle_client_conns))
1036                 goto out;
1037
1038         conn = list_entry(rxnet->idle_client_conns.next,
1039                           struct rxrpc_connection, cache_link);
1040
1041         if (!rxnet->kill_all_client_conns) {
1042                 /* If the number of connections is over the reap limit, we
1043                  * expedite discard by reducing the expiry timeout.  We must,
1044                  * however, have at least a short grace period to be able to do
1045                  * final-ACK or ABORT retransmission.
1046                  */
1047                 expiry = rxrpc_conn_idle_client_expiry;
1048                 if (nr_conns > rxrpc_reap_client_connections)
1049                         expiry = rxrpc_conn_idle_client_fast_expiry;
1050                 if (conn->local->service_closed)
1051                         expiry = rxrpc_closed_conn_expiry * HZ;
1052
1053                 conn_expires_at = conn->idle_timestamp + expiry;
1054
1055                 now = READ_ONCE(jiffies);
1056                 if (time_after(conn_expires_at, now))
1057                         goto not_yet_expired;
1058         }
1059
1060         trace_rxrpc_client(conn, -1, rxrpc_client_discard);
1061         list_del_init(&conn->cache_link);
1062
1063         spin_unlock(&rxnet->client_conn_cache_lock);
1064
1065         rxrpc_unbundle_conn(conn);
1066         rxrpc_put_connection(conn); /* Drop the ->cache_link ref */
1067
1068         nr_conns--;
1069         goto next;
1070
1071 not_yet_expired:
1072         /* The connection at the front of the queue hasn't yet expired, so
1073          * schedule the work item for that point if we discarded something.
1074          *
1075          * We don't worry if the work item is already scheduled - it can look
1076          * after rescheduling itself at a later time.  We could cancel it, but
1077          * then things get messier.
1078          */
1079         _debug("not yet");
1080         if (!rxnet->kill_all_client_conns)
1081                 timer_reduce(&rxnet->client_conn_reap_timer, conn_expires_at);
1082
1083 out:
1084         spin_unlock(&rxnet->client_conn_cache_lock);
1085         spin_unlock(&rxnet->client_conn_discard_lock);
1086         _leave("");
1087 }
1088
1089 /*
1090  * Preemptively destroy all the client connection records rather than waiting
1091  * for them to time out
1092  */
1093 void rxrpc_destroy_all_client_connections(struct rxrpc_net *rxnet)
1094 {
1095         _enter("");
1096
1097         spin_lock(&rxnet->client_conn_cache_lock);
1098         rxnet->kill_all_client_conns = true;
1099         spin_unlock(&rxnet->client_conn_cache_lock);
1100
1101         del_timer_sync(&rxnet->client_conn_reap_timer);
1102
1103         if (!rxrpc_queue_work(&rxnet->client_conn_reaper))
1104                 _debug("destroy: queue failed");
1105
1106         _leave("");
1107 }
1108
1109 /*
1110  * Clean up the client connections on a local endpoint.
1111  */
1112 void rxrpc_clean_up_local_conns(struct rxrpc_local *local)
1113 {
1114         struct rxrpc_connection *conn, *tmp;
1115         struct rxrpc_net *rxnet = local->rxnet;
1116         LIST_HEAD(graveyard);
1117
1118         _enter("");
1119
1120         spin_lock(&rxnet->client_conn_cache_lock);
1121
1122         list_for_each_entry_safe(conn, tmp, &rxnet->idle_client_conns,
1123                                  cache_link) {
1124                 if (conn->local == local) {
1125                         trace_rxrpc_client(conn, -1, rxrpc_client_discard);
1126                         list_move(&conn->cache_link, &graveyard);
1127                 }
1128         }
1129
1130         spin_unlock(&rxnet->client_conn_cache_lock);
1131
1132         while (!list_empty(&graveyard)) {
1133                 conn = list_entry(graveyard.next,
1134                                   struct rxrpc_connection, cache_link);
1135                 list_del_init(&conn->cache_link);
1136                 rxrpc_unbundle_conn(conn);
1137                 rxrpc_put_connection(conn);
1138         }
1139
1140         _leave(" [culled]");
1141 }