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                 trace_rxrpc_bundle(bundle->debug_id, 1, rxrpc_bundle_new);
 137         }
 138         return bundle;
 139 }
 140
 141 struct rxrpc_bundle *rxrpc_get_bundle(struct rxrpc_bundle *bundle,
 142                                       enum rxrpc_bundle_trace why)
 143 {
 144         int r;
 145
 146         __refcount_inc(&bundle->ref, &r);
 147         trace_rxrpc_bundle(bundle->debug_id, r + 1, why);
 148         return bundle;
 149 }
 150
 151 static void rxrpc_free_bundle(struct rxrpc_bundle *bundle)
 152 {
 153         trace_rxrpc_bundle(bundle->debug_id, 1, rxrpc_bundle_free);
 154         rxrpc_put_peer(bundle->peer, rxrpc_peer_put_bundle);
 155         kfree(bundle);
 156 }
 157
 158 void rxrpc_put_bundle(struct rxrpc_bundle *bundle, enum rxrpc_bundle_trace why)
 159 {
 160         unsigned int id = bundle->debug_id;
 161         bool dead;
 162         int r;
 163
 164         dead = __refcount_dec_and_test(&bundle->ref, &r);
 165         trace_rxrpc_bundle(id, r - 1, why);
 166         if (dead)
 167                 rxrpc_free_bundle(bundle);
 168 }
 169
 170 /*
 171  * Allocate a client connection.
 172  */
 173 static struct rxrpc_connection *
 174 rxrpc_alloc_client_connection(struct rxrpc_bundle *bundle, gfp_t gfp)
 175 {
 176         struct rxrpc_connection *conn;
 177         struct rxrpc_net *rxnet = bundle->local->rxnet;
 178         int ret;
 179
 180         _enter("");
 181
 182         conn = rxrpc_alloc_connection(gfp);
 183         if (!conn) {
 184                 _leave(" = -ENOMEM");
 185                 return ERR_PTR(-ENOMEM);
 186         }
 187
 188         refcount_set(&conn->ref, 1);
 189         conn->bundle            = bundle;
 190         conn->local             = bundle->local;
 191         conn->peer              = bundle->peer;
 192         conn->key               = bundle->key;
 193         conn->exclusive         = bundle->exclusive;
 194         conn->upgrade           = bundle->upgrade;
 195         conn->orig_service_id   = bundle->service_id;
 196         conn->security_level    = bundle->security_level;
 197         conn->out_clientflag    = RXRPC_CLIENT_INITIATED;
 198         conn->state             = RXRPC_CONN_CLIENT;
 199         conn->service_id        = conn->orig_service_id;
 200
 201         ret = rxrpc_get_client_connection_id(conn, gfp);
 202         if (ret < 0)
 203                 goto error_0;
 204
 205         ret = rxrpc_init_client_conn_security(conn);
 206         if (ret < 0)
 207                 goto error_1;
 208
 209         atomic_inc(&rxnet->nr_conns);
 210         write_lock(&rxnet->conn_lock);
 211         list_add_tail(&conn->proc_link, &rxnet->conn_proc_list);
 212         write_unlock(&rxnet->conn_lock);
 213
 214         rxrpc_get_bundle(bundle, rxrpc_bundle_get_client_conn);
 215         rxrpc_get_peer(conn->peer, rxrpc_peer_get_client_conn);
 216         rxrpc_get_local(conn->local, rxrpc_local_get_client_conn);
 217         key_get(conn->key);
 218
 219         trace_rxrpc_conn(conn->debug_id, refcount_read(&conn->ref),
 220                          rxrpc_conn_new_client);
 221
 222         atomic_inc(&rxnet->nr_client_conns);
 223         trace_rxrpc_client(conn, -1, rxrpc_client_alloc);
 224         _leave(" = %p", conn);
 225         return conn;
 226
 227 error_1:
 228         rxrpc_put_client_connection_id(conn);
 229 error_0:
 230         kfree(conn);
 231         _leave(" = %d", ret);
 232         return ERR_PTR(ret);
 233 }
 234
 235 /*
 236  * Determine if a connection may be reused.
 237  */
 238 static bool rxrpc_may_reuse_conn(struct rxrpc_connection *conn)
 239 {
 240         struct rxrpc_net *rxnet;
 241         int id_cursor, id, distance, limit;
 242
 243         if (!conn)
 244                 goto dont_reuse;
 245
 246         rxnet = conn->local->rxnet;
 247         if (test_bit(RXRPC_CONN_DONT_REUSE, &conn->flags))
 248                 goto dont_reuse;
 249
 250         if (conn->state != RXRPC_CONN_CLIENT ||
 251             conn->proto.epoch != rxnet->epoch)
 252                 goto mark_dont_reuse;
 253
 254         /* The IDR tree gets very expensive on memory if the connection IDs are
 255          * widely scattered throughout the number space, so we shall want to
 256          * kill off connections that, say, have an ID more than about four
 257          * times the maximum number of client conns away from the current
 258          * allocation point to try and keep the IDs concentrated.
 259          */
 260         id_cursor = idr_get_cursor(&rxrpc_client_conn_ids);
 261         id = conn->proto.cid >> RXRPC_CIDSHIFT;
 262         distance = id - id_cursor;
 263         if (distance < 0)
 264                 distance = -distance;
 265         limit = max_t(unsigned long, atomic_read(&rxnet->nr_conns) * 4, 1024);
 266         if (distance > limit)
 267                 goto mark_dont_reuse;
 268
 269         return true;
 270
 271 mark_dont_reuse:
 272         set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
 273 dont_reuse:
 274         return false;
 275 }
 276
 277 /*
 278  * Look up the conn bundle that matches the connection parameters, adding it if
 279  * it doesn't yet exist.
 280  */
 281 static struct rxrpc_bundle *rxrpc_look_up_bundle(struct rxrpc_conn_parameters *cp,
 282                                                  gfp_t gfp)
 283 {
 284         static atomic_t rxrpc_bundle_id;
 285         struct rxrpc_bundle *bundle, *candidate;
 286         struct rxrpc_local *local = cp->local;
 287         struct rb_node *p, **pp, *parent;
 288         long diff;
 289
 290         _enter("{%px,%x,%u,%u}",
 291                cp->peer, key_serial(cp->key), cp->security_level, cp->upgrade);
 292
 293         if (cp->exclusive)
 294                 return rxrpc_alloc_bundle(cp, gfp);
 295
 296         /* First, see if the bundle is already there. */
 297         _debug("search 1");
 298         spin_lock(&local->client_bundles_lock);
 299         p = local->client_bundles.rb_node;
 300         while (p) {
 301                 bundle = rb_entry(p, struct rxrpc_bundle, local_node);
 302
 303 #define cmp(X) ((long)bundle->X - (long)cp->X)
 304                 diff = (cmp(peer) ?:
 305                         cmp(key) ?:
 306                         cmp(security_level) ?:
 307                         cmp(upgrade));
 308 #undef cmp
 309                 if (diff < 0)
 310                         p = p->rb_left;
 311                 else if (diff > 0)
 312                         p = p->rb_right;
 313                 else
 314                         goto found_bundle;
 315         }
 316         spin_unlock(&local->client_bundles_lock);
 317         _debug("not found");
 318
 319         /* It wasn't.  We need to add one. */
 320         candidate = rxrpc_alloc_bundle(cp, gfp);
 321         if (!candidate)
 322                 return NULL;
 323
 324         _debug("search 2");
 325         spin_lock(&local->client_bundles_lock);
 326         pp = &local->client_bundles.rb_node;
 327         parent = NULL;
 328         while (*pp) {
 329                 parent = *pp;
 330                 bundle = rb_entry(parent, struct rxrpc_bundle, local_node);
 331
 332 #define cmp(X) ((long)bundle->X - (long)cp->X)
 333                 diff = (cmp(peer) ?:
 334                         cmp(key) ?:
 335                         cmp(security_level) ?:
 336                         cmp(upgrade));
 337 #undef cmp
 338                 if (diff < 0)
 339                         pp = &(*pp)->rb_left;
 340                 else if (diff > 0)
 341                         pp = &(*pp)->rb_right;
 342                 else
 343                         goto found_bundle_free;
 344         }
 345
 346         _debug("new bundle");
 347         candidate->debug_id = atomic_inc_return(&rxrpc_bundle_id);
 348         rb_link_node(&candidate->local_node, parent, pp);
 349         rb_insert_color(&candidate->local_node, &local->client_bundles);
 350         rxrpc_get_bundle(candidate, rxrpc_bundle_get_client_call);
 351         spin_unlock(&local->client_bundles_lock);
 352         _leave(" = %u [new]", candidate->debug_id);
 353         return candidate;
 354
 355 found_bundle_free:
 356         rxrpc_free_bundle(candidate);
 357 found_bundle:
 358         rxrpc_get_bundle(bundle, rxrpc_bundle_get_client_call);
 359         atomic_inc(&bundle->active);
 360         spin_unlock(&local->client_bundles_lock);
 361         _leave(" = %u [found]", bundle->debug_id);
 362         return bundle;
 363 }
 364
 365 /*
 366  * Create or find a client bundle to use for a call.
 367  *
 368  * If we return with a connection, the call will be on its waiting list.  It's
 369  * left to the caller to assign a channel and wake up the call.
 370  */
 371 static struct rxrpc_bundle *rxrpc_prep_call(struct rxrpc_sock *rx,
 372                                             struct rxrpc_call *call,
 373                                             struct rxrpc_conn_parameters *cp,
 374                                             struct sockaddr_rxrpc *srx,
 375                                             gfp_t gfp)
 376 {
 377         struct rxrpc_bundle *bundle;
 378
 379         _enter("{%d,%lx},", call->debug_id, call->user_call_ID);
 380
 381         cp->peer = rxrpc_lookup_peer(rx, cp->local, srx, gfp);
 382         if (!cp->peer)
 383                 goto error;
 384
 385         call->tx_last_sent = ktime_get_real();
 386         call->cong_ssthresh = cp->peer->cong_ssthresh;
 387         if (call->cong_cwnd >= call->cong_ssthresh)
 388                 call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
 389         else
 390                 call->cong_mode = RXRPC_CALL_SLOW_START;
 391         if (cp->upgrade)
 392                 __set_bit(RXRPC_CALL_UPGRADE, &call->flags);
 393
 394         /* Find the client connection bundle. */
 395         bundle = rxrpc_look_up_bundle(cp, gfp);
 396         if (!bundle)
 397                 goto error;
 398
 399         /* Get this call queued.  Someone else may activate it whilst we're
 400          * lining up a new connection, but that's fine.
 401          */
 402         spin_lock(&bundle->channel_lock);
 403         list_add_tail(&call->chan_wait_link, &bundle->waiting_calls);
 404         spin_unlock(&bundle->channel_lock);
 405
 406         _leave(" = [B=%x]", bundle->debug_id);
 407         return bundle;
 408
 409 error:
 410         _leave(" = -ENOMEM");
 411         return ERR_PTR(-ENOMEM);
 412 }
 413
 414 /*
 415  * Allocate a new connection and add it into a bundle.
 416  */
 417 static void rxrpc_add_conn_to_bundle(struct rxrpc_bundle *bundle, gfp_t gfp)
 418         __releases(bundle->channel_lock)
 419 {
 420         struct rxrpc_connection *candidate = NULL, *old = NULL;
 421         bool conflict;
 422         int i;
 423
 424         _enter("");
 425
 426         conflict = bundle->alloc_conn;
 427         if (!conflict)
 428                 bundle->alloc_conn = true;
 429         spin_unlock(&bundle->channel_lock);
 430         if (conflict) {
 431                 _leave(" [conf]");
 432                 return;
 433         }
 434
 435         candidate = rxrpc_alloc_client_connection(bundle, gfp);
 436
 437         spin_lock(&bundle->channel_lock);
 438         bundle->alloc_conn = false;
 439
 440         if (IS_ERR(candidate)) {
 441                 bundle->alloc_error = PTR_ERR(candidate);
 442                 spin_unlock(&bundle->channel_lock);
 443                 _leave(" [err %ld]", PTR_ERR(candidate));
 444                 return;
 445         }
 446
 447         bundle->alloc_error = 0;
 448
 449         for (i = 0; i < ARRAY_SIZE(bundle->conns); i++) {
 450                 unsigned int shift = i * RXRPC_MAXCALLS;
 451                 int j;
 452
 453                 old = bundle->conns[i];
 454                 if (!rxrpc_may_reuse_conn(old)) {
 455                         if (old)
 456                                 trace_rxrpc_client(old, -1, rxrpc_client_replace);
 457                         candidate->bundle_shift = shift;
 458                         atomic_inc(&bundle->active);
 459                         bundle->conns[i] = candidate;
 460                         for (j = 0; j < RXRPC_MAXCALLS; j++)
 461                                 set_bit(shift + j, &bundle->avail_chans);
 462                         candidate = NULL;
 463                         break;
 464                 }
 465
 466                 old = NULL;
 467         }
 468
 469         spin_unlock(&bundle->channel_lock);
 470
 471         if (candidate) {
 472                 _debug("discard C=%x", candidate->debug_id);
 473                 trace_rxrpc_client(candidate, -1, rxrpc_client_duplicate);
 474                 rxrpc_put_connection(candidate, rxrpc_conn_put_discard);
 475         }
 476
 477         rxrpc_put_connection(old, rxrpc_conn_put_noreuse);
 478         _leave("");
 479 }
 480
 481 /*
 482  * Add a connection to a bundle if there are no usable connections or we have
 483  * connections waiting for extra capacity.
 484  */
 485 static void rxrpc_maybe_add_conn(struct rxrpc_bundle *bundle, gfp_t gfp)
 486 {
 487         struct rxrpc_call *call;
 488         int i, usable;
 489
 490         _enter("");
 491
 492         spin_lock(&bundle->channel_lock);
 493
 494         /* See if there are any usable connections. */
 495         usable = 0;
 496         for (i = 0; i < ARRAY_SIZE(bundle->conns); i++)
 497                 if (rxrpc_may_reuse_conn(bundle->conns[i]))
 498                         usable++;
 499
 500         if (!usable && !list_empty(&bundle->waiting_calls)) {
 501                 call = list_first_entry(&bundle->waiting_calls,
 502                                         struct rxrpc_call, chan_wait_link);
 503                 if (test_bit(RXRPC_CALL_UPGRADE, &call->flags))
 504                         bundle->try_upgrade = true;
 505         }
 506
 507         if (!usable)
 508                 goto alloc_conn;
 509
 510         if (!bundle->avail_chans &&
 511             !bundle->try_upgrade &&
 512             !list_empty(&bundle->waiting_calls) &&
 513             usable < ARRAY_SIZE(bundle->conns))
 514                 goto alloc_conn;
 515
 516         spin_unlock(&bundle->channel_lock);
 517         _leave("");
 518         return;
 519
 520 alloc_conn:
 521         return rxrpc_add_conn_to_bundle(bundle, gfp);
 522 }
 523
 524 /*
 525  * Assign a channel to the call at the front of the queue and wake the call up.
 526  * We don't increment the callNumber counter until this number has been exposed
 527  * to the world.
 528  */
 529 static void rxrpc_activate_one_channel(struct rxrpc_connection *conn,
 530                                        unsigned int channel)
 531 {
 532         struct rxrpc_channel *chan = &conn->channels[channel];
 533         struct rxrpc_bundle *bundle = conn->bundle;
 534         struct rxrpc_call *call = list_entry(bundle->waiting_calls.next,
 535                                              struct rxrpc_call, chan_wait_link);
 536         u32 call_id = chan->call_counter + 1;
 537
 538         _enter("C=%x,%u", conn->debug_id, channel);
 539
 540         trace_rxrpc_client(conn, channel, rxrpc_client_chan_activate);
 541
 542         /* Cancel the final ACK on the previous call if it hasn't been sent yet
 543          * as the DATA packet will implicitly ACK it.
 544          */
 545         clear_bit(RXRPC_CONN_FINAL_ACK_0 + channel, &conn->flags);
 546         clear_bit(conn->bundle_shift + channel, &bundle->avail_chans);
 547
 548         rxrpc_see_call(call, rxrpc_call_see_activate_client);
 549         list_del_init(&call->chan_wait_link);
 550         call->peer      = rxrpc_get_peer(conn->peer, rxrpc_peer_get_activate_call);
 551         call->conn      = rxrpc_get_connection(conn, rxrpc_conn_get_activate_call);
 552         call->cid       = conn->proto.cid | channel;
 553         call->call_id   = call_id;
 554         call->security  = conn->security;
 555         call->security_ix = conn->security_ix;
 556         call->service_id = conn->service_id;
 557
 558         trace_rxrpc_connect_call(call);
 559
 560         write_lock_bh(&call->state_lock);
 561         call->state = RXRPC_CALL_CLIENT_SEND_REQUEST;
 562         write_unlock_bh(&call->state_lock);
 563
 564         /* Paired with the read barrier in rxrpc_connect_call().  This orders
 565          * cid and epoch in the connection wrt to call_id without the need to
 566          * take the channel_lock.
 567          *
 568          * We provisionally assign a callNumber at this point, but we don't
 569          * confirm it until the call is about to be exposed.
 570          *
 571          * TODO: Pair with a barrier in the data_ready handler when that looks
 572          * at the call ID through a connection channel.
 573          */
 574         smp_wmb();
 575
 576         chan->call_id           = call_id;
 577         chan->call_debug_id     = call->debug_id;
 578         rcu_assign_pointer(chan->call, call);
 579         wake_up(&call->waitq);
 580 }
 581
 582 /*
 583  * Remove a connection from the idle list if it's on it.
 584  */
 585 static void rxrpc_unidle_conn(struct rxrpc_bundle *bundle, struct rxrpc_connection *conn)
 586 {
 587         struct rxrpc_net *rxnet = bundle->local->rxnet;
 588         bool drop_ref;
 589
 590         if (!list_empty(&conn->cache_link)) {
 591                 drop_ref = false;
 592                 spin_lock(&rxnet->client_conn_cache_lock);
 593                 if (!list_empty(&conn->cache_link)) {
 594                         list_del_init(&conn->cache_link);
 595                         drop_ref = true;
 596                 }
 597                 spin_unlock(&rxnet->client_conn_cache_lock);
 598                 if (drop_ref)
 599                         rxrpc_put_connection(conn, rxrpc_conn_put_unidle);
 600         }
 601 }
 602
 603 /*
 604  * Assign channels and callNumbers to waiting calls with channel_lock
 605  * held by caller.
 606  */
 607 static void rxrpc_activate_channels_locked(struct rxrpc_bundle *bundle)
 608 {
 609         struct rxrpc_connection *conn;
 610         unsigned long avail, mask;
 611         unsigned int channel, slot;
 612
 613         if (bundle->try_upgrade)
 614                 mask = 1;
 615         else
 616                 mask = ULONG_MAX;
 617
 618         while (!list_empty(&bundle->waiting_calls)) {
 619                 avail = bundle->avail_chans & mask;
 620                 if (!avail)
 621                         break;
 622                 channel = __ffs(avail);
 623                 clear_bit(channel, &bundle->avail_chans);
 624
 625                 slot = channel / RXRPC_MAXCALLS;
 626                 conn = bundle->conns[slot];
 627                 if (!conn)
 628                         break;
 629
 630                 if (bundle->try_upgrade)
 631                         set_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags);
 632                 rxrpc_unidle_conn(bundle, conn);
 633
 634                 channel &= (RXRPC_MAXCALLS - 1);
 635                 conn->act_chans |= 1 << channel;
 636                 rxrpc_activate_one_channel(conn, channel);
 637         }
 638 }
 639
 640 /*
 641  * Assign channels and callNumbers to waiting calls.
 642  */
 643 static void rxrpc_activate_channels(struct rxrpc_bundle *bundle)
 644 {
 645         _enter("B=%x", bundle->debug_id);
 646
 647         trace_rxrpc_client(NULL, -1, rxrpc_client_activate_chans);
 648
 649         if (!bundle->avail_chans)
 650                 return;
 651
 652         spin_lock(&bundle->channel_lock);
 653         rxrpc_activate_channels_locked(bundle);
 654         spin_unlock(&bundle->channel_lock);
 655         _leave("");
 656 }
 657
 658 /*
 659  * Wait for a callNumber and a channel to be granted to a call.
 660  */
 661 static int rxrpc_wait_for_channel(struct rxrpc_bundle *bundle,
 662                                   struct rxrpc_call *call, gfp_t gfp)
 663 {
 664         DECLARE_WAITQUEUE(myself, current);
 665         int ret = 0;
 666
 667         _enter("%d", call->debug_id);
 668
 669         if (!gfpflags_allow_blocking(gfp)) {
 670                 rxrpc_maybe_add_conn(bundle, gfp);
 671                 rxrpc_activate_channels(bundle);
 672                 ret = bundle->alloc_error ?: -EAGAIN;
 673                 goto out;
 674         }
 675
 676         add_wait_queue_exclusive(&call->waitq, &myself);
 677         for (;;) {
 678                 rxrpc_maybe_add_conn(bundle, gfp);
 679                 rxrpc_activate_channels(bundle);
 680                 ret = bundle->alloc_error;
 681                 if (ret < 0)
 682                         break;
 683
 684                 switch (call->interruptibility) {
 685                 case RXRPC_INTERRUPTIBLE:
 686                 case RXRPC_PREINTERRUPTIBLE:
 687                         set_current_state(TASK_INTERRUPTIBLE);
 688                         break;
 689                 case RXRPC_UNINTERRUPTIBLE:
 690                 default:
 691                         set_current_state(TASK_UNINTERRUPTIBLE);
 692                         break;
 693                 }
 694                 if (READ_ONCE(call->state) != RXRPC_CALL_CLIENT_AWAIT_CONN)
 695                         break;
 696                 if ((call->interruptibility == RXRPC_INTERRUPTIBLE ||
 697                      call->interruptibility == RXRPC_PREINTERRUPTIBLE) &&
 698                     signal_pending(current)) {
 699                         ret = -ERESTARTSYS;
 700                         break;
 701                 }
 702                 schedule();
 703         }
 704         remove_wait_queue(&call->waitq, &myself);
 705         __set_current_state(TASK_RUNNING);
 706
 707 out:
 708         _leave(" = %d", ret);
 709         return ret;
 710 }
 711
 712 /*
 713  * find a connection for a call
 714  * - called in process context with IRQs enabled
 715  */
 716 int rxrpc_connect_call(struct rxrpc_sock *rx,
 717                        struct rxrpc_call *call,
 718                        struct rxrpc_conn_parameters *cp,
 719                        struct sockaddr_rxrpc *srx,
 720                        gfp_t gfp)
 721 {
 722         struct rxrpc_bundle *bundle;
 723         struct rxrpc_net *rxnet = cp->local->rxnet;
 724         int ret = 0;
 725
 726         _enter("{%d,%lx},", call->debug_id, call->user_call_ID);
 727
 728         rxrpc_discard_expired_client_conns(&rxnet->client_conn_reaper);
 729
 730         bundle = rxrpc_prep_call(rx, call, cp, srx, gfp);
 731         if (IS_ERR(bundle)) {
 732                 ret = PTR_ERR(bundle);
 733                 goto out;
 734         }
 735
 736         if (call->state == RXRPC_CALL_CLIENT_AWAIT_CONN) {
 737                 ret = rxrpc_wait_for_channel(bundle, call, gfp);
 738                 if (ret < 0)
 739                         goto wait_failed;
 740         }
 741
 742 granted_channel:
 743         /* Paired with the write barrier in rxrpc_activate_one_channel(). */
 744         smp_rmb();
 745
 746 out_put_bundle:
 747         rxrpc_deactivate_bundle(bundle);
 748         rxrpc_put_bundle(bundle, rxrpc_bundle_get_client_call);
 749 out:
 750         _leave(" = %d", ret);
 751         return ret;
 752
 753 wait_failed:
 754         spin_lock(&bundle->channel_lock);
 755         list_del_init(&call->chan_wait_link);
 756         spin_unlock(&bundle->channel_lock);
 757
 758         if (call->state != RXRPC_CALL_CLIENT_AWAIT_CONN) {
 759                 ret = 0;
 760                 goto granted_channel;
 761         }
 762
 763         trace_rxrpc_client(call->conn, ret, rxrpc_client_chan_wait_failed);
 764         rxrpc_set_call_completion(call, RXRPC_CALL_LOCAL_ERROR, 0, ret);
 765         rxrpc_disconnect_client_call(bundle, call);
 766         goto out_put_bundle;
 767 }
 768
 769 /*
 770  * Note that a call, and thus a connection, is about to be exposed to the
 771  * world.
 772  */
 773 void rxrpc_expose_client_call(struct rxrpc_call *call)
 774 {
 775         unsigned int channel = call->cid & RXRPC_CHANNELMASK;
 776         struct rxrpc_connection *conn = call->conn;
 777         struct rxrpc_channel *chan = &conn->channels[channel];
 778
 779         if (!test_and_set_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 780                 /* Mark the call ID as being used.  If the callNumber counter
 781                  * exceeds ~2 billion, we kill the connection after its
 782                  * outstanding calls have finished so that the counter doesn't
 783                  * wrap.
 784                  */
 785                 chan->call_counter++;
 786                 if (chan->call_counter >= INT_MAX)
 787                         set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
 788                 trace_rxrpc_client(conn, channel, rxrpc_client_exposed);
 789         }
 790 }
 791
 792 /*
 793  * Set the reap timer.
 794  */
 795 static void rxrpc_set_client_reap_timer(struct rxrpc_net *rxnet)
 796 {
 797         if (!rxnet->kill_all_client_conns) {
 798                 unsigned long now = jiffies;
 799                 unsigned long reap_at = now + rxrpc_conn_idle_client_expiry;
 800
 801                 if (rxnet->live)
 802                         timer_reduce(&rxnet->client_conn_reap_timer, reap_at);
 803         }
 804 }
 805
 806 /*
 807  * Disconnect a client call.
 808  */
 809 void rxrpc_disconnect_client_call(struct rxrpc_bundle *bundle, struct rxrpc_call *call)
 810 {
 811         struct rxrpc_connection *conn;
 812         struct rxrpc_channel *chan = NULL;
 813         struct rxrpc_net *rxnet = bundle->local->rxnet;
 814         unsigned int channel;
 815         bool may_reuse;
 816         u32 cid;
 817
 818         _enter("c=%x", call->debug_id);
 819
 820         spin_lock(&bundle->channel_lock);
 821         set_bit(RXRPC_CALL_DISCONNECTED, &call->flags);
 822
 823         /* Calls that have never actually been assigned a channel can simply be
 824          * discarded.
 825          */
 826         conn = call->conn;
 827         if (!conn) {
 828                 _debug("call is waiting");
 829                 ASSERTCMP(call->call_id, ==, 0);
 830                 ASSERT(!test_bit(RXRPC_CALL_EXPOSED, &call->flags));
 831                 list_del_init(&call->chan_wait_link);
 832                 goto out;
 833         }
 834
 835         cid = call->cid;
 836         channel = cid & RXRPC_CHANNELMASK;
 837         chan = &conn->channels[channel];
 838         trace_rxrpc_client(conn, channel, rxrpc_client_chan_disconnect);
 839
 840         if (rcu_access_pointer(chan->call) != call) {
 841                 spin_unlock(&bundle->channel_lock);
 842                 BUG();
 843         }
 844
 845         may_reuse = rxrpc_may_reuse_conn(conn);
 846
 847         /* If a client call was exposed to the world, we save the result for
 848          * retransmission.
 849          *
 850          * We use a barrier here so that the call number and abort code can be
 851          * read without needing to take a lock.
 852          *
 853          * TODO: Make the incoming packet handler check this and handle
 854          * terminal retransmission without requiring access to the call.
 855          */
 856         if (test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 857                 _debug("exposed %u,%u", call->call_id, call->abort_code);
 858                 __rxrpc_disconnect_call(conn, call);
 859
 860                 if (test_and_clear_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags)) {
 861                         trace_rxrpc_client(conn, channel, rxrpc_client_to_active);
 862                         bundle->try_upgrade = false;
 863                         if (may_reuse)
 864                                 rxrpc_activate_channels_locked(bundle);
 865                 }
 866
 867         }
 868
 869         /* See if we can pass the channel directly to another call. */
 870         if (may_reuse && !list_empty(&bundle->waiting_calls)) {
 871                 trace_rxrpc_client(conn, channel, rxrpc_client_chan_pass);
 872                 rxrpc_activate_one_channel(conn, channel);
 873                 goto out;
 874         }
 875
 876         /* Schedule the final ACK to be transmitted in a short while so that it
 877          * can be skipped if we find a follow-on call.  The first DATA packet
 878          * of the follow on call will implicitly ACK this call.
 879          */
 880         if (call->completion == RXRPC_CALL_SUCCEEDED &&
 881             test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 882                 unsigned long final_ack_at = jiffies + 2;
 883
 884                 WRITE_ONCE(chan->final_ack_at, final_ack_at);
 885                 smp_wmb(); /* vs rxrpc_process_delayed_final_acks() */
 886                 set_bit(RXRPC_CONN_FINAL_ACK_0 + channel, &conn->flags);
 887                 rxrpc_reduce_conn_timer(conn, final_ack_at);
 888         }
 889
 890         /* Deactivate the channel. */
 891         rcu_assign_pointer(chan->call, NULL);
 892         set_bit(conn->bundle_shift + channel, &conn->bundle->avail_chans);
 893         conn->act_chans &= ~(1 << channel);
 894
 895         /* If no channels remain active, then put the connection on the idle
 896          * list for a short while.  Give it a ref to stop it going away if it
 897          * becomes unbundled.
 898          */
 899         if (!conn->act_chans) {
 900                 trace_rxrpc_client(conn, channel, rxrpc_client_to_idle);
 901                 conn->idle_timestamp = jiffies;
 902
 903                 rxrpc_get_connection(conn, rxrpc_conn_get_idle);
 904                 spin_lock(&rxnet->client_conn_cache_lock);
 905                 list_move_tail(&conn->cache_link, &rxnet->idle_client_conns);
 906                 spin_unlock(&rxnet->client_conn_cache_lock);
 907
 908                 rxrpc_set_client_reap_timer(rxnet);
 909         }
 910
 911 out:
 912         spin_unlock(&bundle->channel_lock);
 913         _leave("");
 914         return;
 915 }
 916
 917 /*
 918  * Remove a connection from a bundle.
 919  */
 920 static void rxrpc_unbundle_conn(struct rxrpc_connection *conn)
 921 {
 922         struct rxrpc_bundle *bundle = conn->bundle;
 923         unsigned int bindex;
 924         bool need_drop = false;
 925         int i;
 926
 927         _enter("C=%x", conn->debug_id);
 928
 929         if (conn->flags & RXRPC_CONN_FINAL_ACK_MASK)
 930                 rxrpc_process_delayed_final_acks(conn, true);
 931
 932         spin_lock(&bundle->channel_lock);
 933         bindex = conn->bundle_shift / RXRPC_MAXCALLS;
 934         if (bundle->conns[bindex] == conn) {
 935                 _debug("clear slot %u", bindex);
 936                 bundle->conns[bindex] = NULL;
 937                 for (i = 0; i < RXRPC_MAXCALLS; i++)
 938                         clear_bit(conn->bundle_shift + i, &bundle->avail_chans);
 939                 need_drop = true;
 940         }
 941         spin_unlock(&bundle->channel_lock);
 942
 943         if (need_drop) {
 944                 rxrpc_deactivate_bundle(bundle);
 945                 rxrpc_put_connection(conn, rxrpc_conn_put_unbundle);
 946         }
 947 }
 948
 949 /*
 950  * Drop the active count on a bundle.
 951  */
 952 static void rxrpc_deactivate_bundle(struct rxrpc_bundle *bundle)
 953 {
 954         struct rxrpc_local *local = bundle->local;
 955         bool need_put = false;
 956
 957         if (atomic_dec_and_lock(&bundle->active, &local->client_bundles_lock)) {
 958                 if (!bundle->exclusive) {
 959                         _debug("erase bundle");
 960                         rb_erase(&bundle->local_node, &local->client_bundles);
 961                         need_put = true;
 962                 }
 963
 964                 spin_unlock(&local->client_bundles_lock);
 965                 if (need_put)
 966                         rxrpc_put_bundle(bundle, rxrpc_bundle_put_discard);
 967         }
 968 }
 969
 970 /*
 971  * Clean up a dead client connection.
 972  */
 973 static void rxrpc_kill_client_conn(struct rxrpc_connection *conn)
 974 {
 975         struct rxrpc_local *local = conn->local;
 976         struct rxrpc_net *rxnet = local->rxnet;
 977
 978         _enter("C=%x", conn->debug_id);
 979
 980         trace_rxrpc_client(conn, -1, rxrpc_client_cleanup);
 981         atomic_dec(&rxnet->nr_client_conns);
 982
 983         rxrpc_put_client_connection_id(conn);
 984         rxrpc_kill_connection(conn);
 985 }
 986
 987 /*
 988  * Clean up a dead client connections.
 989  */
 990 void rxrpc_put_client_conn(struct rxrpc_connection *conn,
 991                            enum rxrpc_conn_trace why)
 992 {
 993         unsigned int debug_id = conn->debug_id;
 994         bool dead;
 995         int r;
 996
 997         dead = __refcount_dec_and_test(&conn->ref, &r);
 998         trace_rxrpc_conn(debug_id, r - 1, why);
 999         if (dead)
1000                 rxrpc_kill_client_conn(conn);
1001 }
1002
1003 /*
1004  * Discard expired client connections from the idle list.  Each conn in the
1005  * idle list has been exposed and holds an extra ref because of that.
1006  *
1007  * This may be called from conn setup or from a work item so cannot be
1008  * considered non-reentrant.
1009  */
1010 void rxrpc_discard_expired_client_conns(struct work_struct *work)
1011 {
1012         struct rxrpc_connection *conn;
1013         struct rxrpc_net *rxnet =
1014                 container_of(work, struct rxrpc_net, client_conn_reaper);
1015         unsigned long expiry, conn_expires_at, now;
1016         unsigned int nr_conns;
1017
1018         _enter("");
1019
1020         if (list_empty(&rxnet->idle_client_conns)) {
1021                 _leave(" [empty]");
1022                 return;
1023         }
1024
1025         /* Don't double up on the discarding */
1026         if (!spin_trylock(&rxnet->client_conn_discard_lock)) {
1027                 _leave(" [already]");
1028                 return;
1029         }
1030
1031         /* We keep an estimate of what the number of conns ought to be after
1032          * we've discarded some so that we don't overdo the discarding.
1033          */
1034         nr_conns = atomic_read(&rxnet->nr_client_conns);
1035
1036 next:
1037         spin_lock(&rxnet->client_conn_cache_lock);
1038
1039         if (list_empty(&rxnet->idle_client_conns))
1040                 goto out;
1041
1042         conn = list_entry(rxnet->idle_client_conns.next,
1043                           struct rxrpc_connection, cache_link);
1044
1045         if (!rxnet->kill_all_client_conns) {
1046                 /* If the number of connections is over the reap limit, we
1047                  * expedite discard by reducing the expiry timeout.  We must,
1048                  * however, have at least a short grace period to be able to do
1049                  * final-ACK or ABORT retransmission.
1050                  */
1051                 expiry = rxrpc_conn_idle_client_expiry;
1052                 if (nr_conns > rxrpc_reap_client_connections)
1053                         expiry = rxrpc_conn_idle_client_fast_expiry;
1054                 if (conn->local->service_closed)
1055                         expiry = rxrpc_closed_conn_expiry * HZ;
1056
1057                 conn_expires_at = conn->idle_timestamp + expiry;
1058
1059                 now = READ_ONCE(jiffies);
1060                 if (time_after(conn_expires_at, now))
1061                         goto not_yet_expired;
1062         }
1063
1064         trace_rxrpc_client(conn, -1, rxrpc_client_discard);
1065         list_del_init(&conn->cache_link);
1066
1067         spin_unlock(&rxnet->client_conn_cache_lock);
1068
1069         rxrpc_unbundle_conn(conn);
1070         /* Drop the ->cache_link ref */
1071         rxrpc_put_connection(conn, rxrpc_conn_put_discard_idle);
1072
1073         nr_conns--;
1074         goto next;
1075
1076 not_yet_expired:
1077         /* The connection at the front of the queue hasn't yet expired, so
1078          * schedule the work item for that point if we discarded something.
1079          *
1080          * We don't worry if the work item is already scheduled - it can look
1081          * after rescheduling itself at a later time.  We could cancel it, but
1082          * then things get messier.
1083          */
1084         _debug("not yet");
1085         if (!rxnet->kill_all_client_conns)
1086                 timer_reduce(&rxnet->client_conn_reap_timer, conn_expires_at);
1087
1088 out:
1089         spin_unlock(&rxnet->client_conn_cache_lock);
1090         spin_unlock(&rxnet->client_conn_discard_lock);
1091         _leave("");
1092 }
1093
1094 /*
1095  * Preemptively destroy all the client connection records rather than waiting
1096  * for them to time out
1097  */
1098 void rxrpc_destroy_all_client_connections(struct rxrpc_net *rxnet)
1099 {
1100         _enter("");
1101
1102         spin_lock(&rxnet->client_conn_cache_lock);
1103         rxnet->kill_all_client_conns = true;
1104         spin_unlock(&rxnet->client_conn_cache_lock);
1105
1106         del_timer_sync(&rxnet->client_conn_reap_timer);
1107
1108         if (!rxrpc_queue_work(&rxnet->client_conn_reaper))
1109                 _debug("destroy: queue failed");
1110
1111         _leave("");
1112 }
1113
1114 /*
1115  * Clean up the client connections on a local endpoint.
1116  */
1117 void rxrpc_clean_up_local_conns(struct rxrpc_local *local)
1118 {
1119         struct rxrpc_connection *conn, *tmp;
1120         struct rxrpc_net *rxnet = local->rxnet;
1121         LIST_HEAD(graveyard);
1122
1123         _enter("");
1124
1125         spin_lock(&rxnet->client_conn_cache_lock);
1126
1127         list_for_each_entry_safe(conn, tmp, &rxnet->idle_client_conns,
1128                                  cache_link) {
1129                 if (conn->local == local) {
1130                         trace_rxrpc_client(conn, -1, rxrpc_client_discard);
1131                         list_move(&conn->cache_link, &graveyard);
1132                 }
1133         }
1134
1135         spin_unlock(&rxnet->client_conn_cache_lock);
1136
1137         while (!list_empty(&graveyard)) {
1138                 conn = list_entry(graveyard.next,
1139                                   struct rxrpc_connection, cache_link);
1140                 list_del_init(&conn->cache_link);
1141                 rxrpc_unbundle_conn(conn);
1142                 rxrpc_put_connection(conn, rxrpc_conn_put_local_dead);
1143         }
1144
1145         _leave(" [culled]");
1146 }