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 /*
  44  * Get a connection ID and epoch for a client connection from the global pool.
  45  * The connection struct pointer is then recorded in the idr radix tree.  The
  46  * epoch doesn't change until the client is rebooted (or, at least, unless the
  47  * module is unloaded).
  48  */
  49 static int rxrpc_get_client_connection_id(struct rxrpc_connection *conn,
  50                                           gfp_t gfp)
  51 {
  52         struct rxrpc_net *rxnet = conn->params.local->rxnet;
  53         int id;
  54
  55         _enter("");
  56
  57         idr_preload(gfp);
  58         spin_lock(&rxrpc_conn_id_lock);
  59
  60         id = idr_alloc_cyclic(&rxrpc_client_conn_ids, conn,
  61                               1, 0x40000000, GFP_NOWAIT);
  62         if (id < 0)
  63                 goto error;
  64
  65         spin_unlock(&rxrpc_conn_id_lock);
  66         idr_preload_end();
  67
  68         conn->proto.epoch = rxnet->epoch;
  69         conn->proto.cid = id << RXRPC_CIDSHIFT;
  70         set_bit(RXRPC_CONN_HAS_IDR, &conn->flags);
  71         _leave(" [CID %x]", conn->proto.cid);
  72         return 0;
  73
  74 error:
  75         spin_unlock(&rxrpc_conn_id_lock);
  76         idr_preload_end();
  77         _leave(" = %d", id);
  78         return id;
  79 }
  80
  81 /*
  82  * Release a connection ID for a client connection from the global pool.
  83  */
  84 static void rxrpc_put_client_connection_id(struct rxrpc_connection *conn)
  85 {
  86         if (test_bit(RXRPC_CONN_HAS_IDR, &conn->flags)) {
  87                 spin_lock(&rxrpc_conn_id_lock);
  88                 idr_remove(&rxrpc_client_conn_ids,
  89                            conn->proto.cid >> RXRPC_CIDSHIFT);
  90                 spin_unlock(&rxrpc_conn_id_lock);
  91         }
  92 }
  93
  94 /*
  95  * Destroy the client connection ID tree.
  96  */
  97 void rxrpc_destroy_client_conn_ids(void)
  98 {
  99         struct rxrpc_connection *conn;
 100         int id;
 101
 102         if (!idr_is_empty(&rxrpc_client_conn_ids)) {
 103                 idr_for_each_entry(&rxrpc_client_conn_ids, conn, id) {
 104                         pr_err("AF_RXRPC: Leaked client conn %p {%d}\n",
 105                                conn, atomic_read(&conn->usage));
 106                 }
 107                 BUG();
 108         }
 109
 110         idr_destroy(&rxrpc_client_conn_ids);
 111 }
 112
 113 /*
 114  * Allocate a connection bundle.
 115  */
 116 static struct rxrpc_bundle *rxrpc_alloc_bundle(struct rxrpc_conn_parameters *cp,
 117                                                gfp_t gfp)
 118 {
 119         struct rxrpc_bundle *bundle;
 120
 121         bundle = kzalloc(sizeof(*bundle), gfp);
 122         if (bundle) {
 123                 bundle->params = *cp;
 124                 rxrpc_get_peer(bundle->params.peer);
 125                 atomic_set(&bundle->usage, 1);
 126                 spin_lock_init(&bundle->channel_lock);
 127                 INIT_LIST_HEAD(&bundle->waiting_calls);
 128         }
 129         return bundle;
 130 }
 131
 132 struct rxrpc_bundle *rxrpc_get_bundle(struct rxrpc_bundle *bundle)
 133 {
 134         atomic_inc(&bundle->usage);
 135         return bundle;
 136 }
 137
 138 void rxrpc_put_bundle(struct rxrpc_bundle *bundle)
 139 {
 140         unsigned int d = bundle->debug_id;
 141         unsigned int u = atomic_dec_return(&bundle->usage);
 142
 143         _debug("PUT B=%x %u", d, u);
 144         if (u == 0) {
 145                 rxrpc_put_peer(bundle->params.peer);
 146                 kfree(bundle);
 147         }
 148 }
 149
 150 /*
 151  * Allocate a client connection.
 152  */
 153 static struct rxrpc_connection *
 154 rxrpc_alloc_client_connection(struct rxrpc_bundle *bundle, gfp_t gfp)
 155 {
 156         struct rxrpc_connection *conn;
 157         struct rxrpc_net *rxnet = bundle->params.local->rxnet;
 158         int ret;
 159
 160         _enter("");
 161
 162         conn = rxrpc_alloc_connection(gfp);
 163         if (!conn) {
 164                 _leave(" = -ENOMEM");
 165                 return ERR_PTR(-ENOMEM);
 166         }
 167
 168         atomic_set(&conn->usage, 1);
 169         conn->bundle            = bundle;
 170         conn->params            = bundle->params;
 171         conn->out_clientflag    = RXRPC_CLIENT_INITIATED;
 172         conn->state             = RXRPC_CONN_CLIENT;
 173         conn->service_id        = conn->params.service_id;
 174
 175         ret = rxrpc_get_client_connection_id(conn, gfp);
 176         if (ret < 0)
 177                 goto error_0;
 178
 179         ret = rxrpc_init_client_conn_security(conn);
 180         if (ret < 0)
 181                 goto error_1;
 182
 183         ret = conn->security->prime_packet_security(conn);
 184         if (ret < 0)
 185                 goto error_2;
 186
 187         atomic_inc(&rxnet->nr_conns);
 188         write_lock(&rxnet->conn_lock);
 189         list_add_tail(&conn->proc_link, &rxnet->conn_proc_list);
 190         write_unlock(&rxnet->conn_lock);
 191
 192         rxrpc_get_bundle(bundle);
 193         rxrpc_get_peer(conn->params.peer);
 194         rxrpc_get_local(conn->params.local);
 195         key_get(conn->params.key);
 196
 197         trace_rxrpc_conn(conn->debug_id, rxrpc_conn_new_client,
 198                          atomic_read(&conn->usage),
 199                          __builtin_return_address(0));
 200
 201         atomic_inc(&rxnet->nr_client_conns);
 202         trace_rxrpc_client(conn, -1, rxrpc_client_alloc);
 203         _leave(" = %p", conn);
 204         return conn;
 205
 206 error_2:
 207         conn->security->clear(conn);
 208 error_1:
 209         rxrpc_put_client_connection_id(conn);
 210 error_0:
 211         kfree(conn);
 212         _leave(" = %d", ret);
 213         return ERR_PTR(ret);
 214 }
 215
 216 /*
 217  * Determine if a connection may be reused.
 218  */
 219 static bool rxrpc_may_reuse_conn(struct rxrpc_connection *conn)
 220 {
 221         struct rxrpc_net *rxnet;
 222         int id_cursor, id, distance, limit;
 223
 224         if (!conn)
 225                 goto dont_reuse;
 226
 227         rxnet = conn->params.local->rxnet;
 228         if (test_bit(RXRPC_CONN_DONT_REUSE, &conn->flags))
 229                 goto dont_reuse;
 230
 231         if (conn->state != RXRPC_CONN_CLIENT ||
 232             conn->proto.epoch != rxnet->epoch)
 233                 goto mark_dont_reuse;
 234
 235         /* The IDR tree gets very expensive on memory if the connection IDs are
 236          * widely scattered throughout the number space, so we shall want to
 237          * kill off connections that, say, have an ID more than about four
 238          * times the maximum number of client conns away from the current
 239          * allocation point to try and keep the IDs concentrated.
 240          */
 241         id_cursor = idr_get_cursor(&rxrpc_client_conn_ids);
 242         id = conn->proto.cid >> RXRPC_CIDSHIFT;
 243         distance = id - id_cursor;
 244         if (distance < 0)
 245                 distance = -distance;
 246         limit = max_t(unsigned long, atomic_read(&rxnet->nr_conns) * 4, 1024);
 247         if (distance > limit)
 248                 goto mark_dont_reuse;
 249
 250         return true;
 251
 252 mark_dont_reuse:
 253         set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
 254 dont_reuse:
 255         return false;
 256 }
 257
 258 /*
 259  * Look up the conn bundle that matches the connection parameters, adding it if
 260  * it doesn't yet exist.
 261  */
 262 static struct rxrpc_bundle *rxrpc_look_up_bundle(struct rxrpc_conn_parameters *cp,
 263                                                  gfp_t gfp)
 264 {
 265         static atomic_t rxrpc_bundle_id;
 266         struct rxrpc_bundle *bundle, *candidate;
 267         struct rxrpc_local *local = cp->local;
 268         struct rb_node *p, **pp, *parent;
 269         long diff;
 270
 271         _enter("{%px,%x,%u,%u}",
 272                cp->peer, key_serial(cp->key), cp->security_level, cp->upgrade);
 273
 274         if (cp->exclusive)
 275                 return rxrpc_alloc_bundle(cp, gfp);
 276
 277         /* First, see if the bundle is already there. */
 278         _debug("search 1");
 279         spin_lock(&local->client_bundles_lock);
 280         p = local->client_bundles.rb_node;
 281         while (p) {
 282                 bundle = rb_entry(p, struct rxrpc_bundle, local_node);
 283
 284 #define cmp(X) ((long)bundle->params.X - (long)cp->X)
 285                 diff = (cmp(peer) ?:
 286                         cmp(key) ?:
 287                         cmp(security_level) ?:
 288                         cmp(upgrade));
 289 #undef cmp
 290                 if (diff < 0)
 291                         p = p->rb_left;
 292                 else if (diff > 0)
 293                         p = p->rb_right;
 294                 else
 295                         goto found_bundle;
 296         }
 297         spin_unlock(&local->client_bundles_lock);
 298         _debug("not found");
 299
 300         /* It wasn't.  We need to add one. */
 301         candidate = rxrpc_alloc_bundle(cp, gfp);
 302         if (!candidate)
 303                 return NULL;
 304
 305         _debug("search 2");
 306         spin_lock(&local->client_bundles_lock);
 307         pp = &local->client_bundles.rb_node;
 308         parent = NULL;
 309         while (*pp) {
 310                 parent = *pp;
 311                 bundle = rb_entry(parent, struct rxrpc_bundle, local_node);
 312
 313 #define cmp(X) ((long)bundle->params.X - (long)cp->X)
 314                 diff = (cmp(peer) ?:
 315                         cmp(key) ?:
 316                         cmp(security_level) ?:
 317                         cmp(upgrade));
 318 #undef cmp
 319                 if (diff < 0)
 320                         pp = &(*pp)->rb_left;
 321                 else if (diff > 0)
 322                         pp = &(*pp)->rb_right;
 323                 else
 324                         goto found_bundle_free;
 325         }
 326
 327         _debug("new bundle");
 328         candidate->debug_id = atomic_inc_return(&rxrpc_bundle_id);
 329         rb_link_node(&candidate->local_node, parent, pp);
 330         rb_insert_color(&candidate->local_node, &local->client_bundles);
 331         rxrpc_get_bundle(candidate);
 332         spin_unlock(&local->client_bundles_lock);
 333         _leave(" = %u [new]", candidate->debug_id);
 334         return candidate;
 335
 336 found_bundle_free:
 337         kfree(candidate);
 338 found_bundle:
 339         rxrpc_get_bundle(bundle);
 340         spin_unlock(&local->client_bundles_lock);
 341         _leave(" = %u [found]", bundle->debug_id);
 342         return bundle;
 343 }
 344
 345 /*
 346  * Create or find a client bundle to use for a call.
 347  *
 348  * If we return with a connection, the call will be on its waiting list.  It's
 349  * left to the caller to assign a channel and wake up the call.
 350  */
 351 static struct rxrpc_bundle *rxrpc_prep_call(struct rxrpc_sock *rx,
 352                                             struct rxrpc_call *call,
 353                                             struct rxrpc_conn_parameters *cp,
 354                                             struct sockaddr_rxrpc *srx,
 355                                             gfp_t gfp)
 356 {
 357         struct rxrpc_bundle *bundle;
 358
 359         _enter("{%d,%lx},", call->debug_id, call->user_call_ID);
 360
 361         cp->peer = rxrpc_lookup_peer(rx, cp->local, srx, gfp);
 362         if (!cp->peer)
 363                 goto error;
 364
 365         call->cong_cwnd = cp->peer->cong_cwnd;
 366         if (call->cong_cwnd >= call->cong_ssthresh)
 367                 call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
 368         else
 369                 call->cong_mode = RXRPC_CALL_SLOW_START;
 370         if (cp->upgrade)
 371                 __set_bit(RXRPC_CALL_UPGRADE, &call->flags);
 372
 373         /* Find the client connection bundle. */
 374         bundle = rxrpc_look_up_bundle(cp, gfp);
 375         if (!bundle)
 376                 goto error;
 377
 378         /* Get this call queued.  Someone else may activate it whilst we're
 379          * lining up a new connection, but that's fine.
 380          */
 381         spin_lock(&bundle->channel_lock);
 382         list_add_tail(&call->chan_wait_link, &bundle->waiting_calls);
 383         spin_unlock(&bundle->channel_lock);
 384
 385         _leave(" = [B=%x]", bundle->debug_id);
 386         return bundle;
 387
 388 error:
 389         _leave(" = -ENOMEM");
 390         return ERR_PTR(-ENOMEM);
 391 }
 392
 393 /*
 394  * Allocate a new connection and add it into a bundle.
 395  */
 396 static void rxrpc_add_conn_to_bundle(struct rxrpc_bundle *bundle, gfp_t gfp)
 397         __releases(bundle->channel_lock)
 398 {
 399         struct rxrpc_connection *candidate = NULL, *old = NULL;
 400         bool conflict;
 401         int i;
 402
 403         _enter("");
 404
 405         conflict = bundle->alloc_conn;
 406         if (!conflict)
 407                 bundle->alloc_conn = true;
 408         spin_unlock(&bundle->channel_lock);
 409         if (conflict) {
 410                 _leave(" [conf]");
 411                 return;
 412         }
 413
 414         candidate = rxrpc_alloc_client_connection(bundle, gfp);
 415
 416         spin_lock(&bundle->channel_lock);
 417         bundle->alloc_conn = false;
 418
 419         if (IS_ERR(candidate)) {
 420                 bundle->alloc_error = PTR_ERR(candidate);
 421                 spin_unlock(&bundle->channel_lock);
 422                 _leave(" [err %ld]", PTR_ERR(candidate));
 423                 return;
 424         }
 425
 426         bundle->alloc_error = 0;
 427
 428         for (i = 0; i < ARRAY_SIZE(bundle->conns); i++) {
 429                 unsigned int shift = i * RXRPC_MAXCALLS;
 430                 int j;
 431
 432                 old = bundle->conns[i];
 433                 if (!rxrpc_may_reuse_conn(old)) {
 434                         if (old)
 435                                 trace_rxrpc_client(old, -1, rxrpc_client_replace);
 436                         candidate->bundle_shift = shift;
 437                         bundle->conns[i] = candidate;
 438                         for (j = 0; j < RXRPC_MAXCALLS; j++)
 439                                 set_bit(shift + j, &bundle->avail_chans);
 440                         candidate = NULL;
 441                         break;
 442                 }
 443
 444                 old = NULL;
 445         }
 446
 447         spin_unlock(&bundle->channel_lock);
 448
 449         if (candidate) {
 450                 _debug("discard C=%x", candidate->debug_id);
 451                 trace_rxrpc_client(candidate, -1, rxrpc_client_duplicate);
 452                 rxrpc_put_connection(candidate);
 453         }
 454
 455         rxrpc_put_connection(old);
 456         _leave("");
 457 }
 458
 459 /*
 460  * Add a connection to a bundle if there are no usable connections or we have
 461  * connections waiting for extra capacity.
 462  */
 463 static void rxrpc_maybe_add_conn(struct rxrpc_bundle *bundle, gfp_t gfp)
 464 {
 465         struct rxrpc_call *call;
 466         int i, usable;
 467
 468         _enter("");
 469
 470         spin_lock(&bundle->channel_lock);
 471
 472         /* See if there are any usable connections. */
 473         usable = 0;
 474         for (i = 0; i < ARRAY_SIZE(bundle->conns); i++)
 475                 if (rxrpc_may_reuse_conn(bundle->conns[i]))
 476                         usable++;
 477
 478         if (!usable && !list_empty(&bundle->waiting_calls)) {
 479                 call = list_first_entry(&bundle->waiting_calls,
 480                                         struct rxrpc_call, chan_wait_link);
 481                 if (test_bit(RXRPC_CALL_UPGRADE, &call->flags))
 482                         bundle->try_upgrade = true;
 483         }
 484
 485         if (!usable)
 486                 goto alloc_conn;
 487
 488         if (!bundle->avail_chans &&
 489             !bundle->try_upgrade &&
 490             !list_empty(&bundle->waiting_calls) &&
 491             usable < ARRAY_SIZE(bundle->conns))
 492                 goto alloc_conn;
 493
 494         spin_unlock(&bundle->channel_lock);
 495         _leave("");
 496         return;
 497
 498 alloc_conn:
 499         return rxrpc_add_conn_to_bundle(bundle, gfp);
 500 }
 501
 502 /*
 503  * Assign a channel to the call at the front of the queue and wake the call up.
 504  * We don't increment the callNumber counter until this number has been exposed
 505  * to the world.
 506  */
 507 static void rxrpc_activate_one_channel(struct rxrpc_connection *conn,
 508                                        unsigned int channel)
 509 {
 510         struct rxrpc_channel *chan = &conn->channels[channel];
 511         struct rxrpc_bundle *bundle = conn->bundle;
 512         struct rxrpc_call *call = list_entry(bundle->waiting_calls.next,
 513                                              struct rxrpc_call, chan_wait_link);
 514         u32 call_id = chan->call_counter + 1;
 515
 516         _enter("C=%x,%u", conn->debug_id, channel);
 517
 518         trace_rxrpc_client(conn, channel, rxrpc_client_chan_activate);
 519
 520         /* Cancel the final ACK on the previous call if it hasn't been sent yet
 521          * as the DATA packet will implicitly ACK it.
 522          */
 523         clear_bit(RXRPC_CONN_FINAL_ACK_0 + channel, &conn->flags);
 524         clear_bit(conn->bundle_shift + channel, &bundle->avail_chans);
 525
 526         rxrpc_see_call(call);
 527         list_del_init(&call->chan_wait_link);
 528         call->peer      = rxrpc_get_peer(conn->params.peer);
 529         call->conn      = rxrpc_get_connection(conn);
 530         call->cid       = conn->proto.cid | channel;
 531         call->call_id   = call_id;
 532         call->security  = conn->security;
 533         call->security_ix = conn->security_ix;
 534         call->service_id = conn->service_id;
 535
 536         trace_rxrpc_connect_call(call);
 537         _net("CONNECT call %08x:%08x as call %d on conn %d",
 538              call->cid, call->call_id, call->debug_id, conn->debug_id);
 539
 540         write_lock_bh(&call->state_lock);
 541         call->state = RXRPC_CALL_CLIENT_SEND_REQUEST;
 542         write_unlock_bh(&call->state_lock);
 543
 544         /* Paired with the read barrier in rxrpc_connect_call().  This orders
 545          * cid and epoch in the connection wrt to call_id without the need to
 546          * take the channel_lock.
 547          *
 548          * We provisionally assign a callNumber at this point, but we don't
 549          * confirm it until the call is about to be exposed.
 550          *
 551          * TODO: Pair with a barrier in the data_ready handler when that looks
 552          * at the call ID through a connection channel.
 553          */
 554         smp_wmb();
 555
 556         chan->call_id           = call_id;
 557         chan->call_debug_id     = call->debug_id;
 558         rcu_assign_pointer(chan->call, call);
 559         wake_up(&call->waitq);
 560 }
 561
 562 /*
 563  * Remove a connection from the idle list if it's on it.
 564  */
 565 static void rxrpc_unidle_conn(struct rxrpc_bundle *bundle, struct rxrpc_connection *conn)
 566 {
 567         struct rxrpc_net *rxnet = bundle->params.local->rxnet;
 568         bool drop_ref;
 569
 570         if (!list_empty(&conn->cache_link)) {
 571                 drop_ref = false;
 572                 spin_lock(&rxnet->client_conn_cache_lock);
 573                 if (!list_empty(&conn->cache_link)) {
 574                         list_del_init(&conn->cache_link);
 575                         drop_ref = true;
 576                 }
 577                 spin_unlock(&rxnet->client_conn_cache_lock);
 578                 if (drop_ref)
 579                         rxrpc_put_connection(conn);
 580         }
 581 }
 582
 583 /*
 584  * Assign channels and callNumbers to waiting calls with channel_lock
 585  * held by caller.
 586  */
 587 static void rxrpc_activate_channels_locked(struct rxrpc_bundle *bundle)
 588 {
 589         struct rxrpc_connection *conn;
 590         unsigned long avail, mask;
 591         unsigned int channel, slot;
 592
 593         if (bundle->try_upgrade)
 594                 mask = 1;
 595         else
 596                 mask = ULONG_MAX;
 597
 598         while (!list_empty(&bundle->waiting_calls)) {
 599                 avail = bundle->avail_chans & mask;
 600                 if (!avail)
 601                         break;
 602                 channel = __ffs(avail);
 603                 clear_bit(channel, &bundle->avail_chans);
 604
 605                 slot = channel / RXRPC_MAXCALLS;
 606                 conn = bundle->conns[slot];
 607                 if (!conn)
 608                         break;
 609
 610                 if (bundle->try_upgrade)
 611                         set_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags);
 612                 rxrpc_unidle_conn(bundle, conn);
 613
 614                 channel &= (RXRPC_MAXCALLS - 1);
 615                 conn->act_chans |= 1 << channel;
 616                 rxrpc_activate_one_channel(conn, channel);
 617         }
 618 }
 619
 620 /*
 621  * Assign channels and callNumbers to waiting calls.
 622  */
 623 static void rxrpc_activate_channels(struct rxrpc_bundle *bundle)
 624 {
 625         _enter("B=%x", bundle->debug_id);
 626
 627         trace_rxrpc_client(NULL, -1, rxrpc_client_activate_chans);
 628
 629         if (!bundle->avail_chans)
 630                 return;
 631
 632         spin_lock(&bundle->channel_lock);
 633         rxrpc_activate_channels_locked(bundle);
 634         spin_unlock(&bundle->channel_lock);
 635         _leave("");
 636 }
 637
 638 /*
 639  * Wait for a callNumber and a channel to be granted to a call.
 640  */
 641 static int rxrpc_wait_for_channel(struct rxrpc_bundle *bundle,
 642                                   struct rxrpc_call *call, gfp_t gfp)
 643 {
 644         DECLARE_WAITQUEUE(myself, current);
 645         int ret = 0;
 646
 647         _enter("%d", call->debug_id);
 648
 649         if (!gfpflags_allow_blocking(gfp)) {
 650                 rxrpc_maybe_add_conn(bundle, gfp);
 651                 rxrpc_activate_channels(bundle);
 652                 ret = bundle->alloc_error ?: -EAGAIN;
 653                 goto out;
 654         }
 655
 656         add_wait_queue_exclusive(&call->waitq, &myself);
 657         for (;;) {
 658                 rxrpc_maybe_add_conn(bundle, gfp);
 659                 rxrpc_activate_channels(bundle);
 660                 ret = bundle->alloc_error;
 661                 if (ret < 0)
 662                         break;
 663
 664                 switch (call->interruptibility) {
 665                 case RXRPC_INTERRUPTIBLE:
 666                 case RXRPC_PREINTERRUPTIBLE:
 667                         set_current_state(TASK_INTERRUPTIBLE);
 668                         break;
 669                 case RXRPC_UNINTERRUPTIBLE:
 670                 default:
 671                         set_current_state(TASK_UNINTERRUPTIBLE);
 672                         break;
 673                 }
 674                 if (READ_ONCE(call->state) != RXRPC_CALL_CLIENT_AWAIT_CONN)
 675                         break;
 676                 if ((call->interruptibility == RXRPC_INTERRUPTIBLE ||
 677                      call->interruptibility == RXRPC_PREINTERRUPTIBLE) &&
 678                     signal_pending(current)) {
 679                         ret = -ERESTARTSYS;
 680                         break;
 681                 }
 682                 schedule();
 683         }
 684         remove_wait_queue(&call->waitq, &myself);
 685         __set_current_state(TASK_RUNNING);
 686
 687 out:
 688         _leave(" = %d", ret);
 689         return ret;
 690 }
 691
 692 /*
 693  * find a connection for a call
 694  * - called in process context with IRQs enabled
 695  */
 696 int rxrpc_connect_call(struct rxrpc_sock *rx,
 697                        struct rxrpc_call *call,
 698                        struct rxrpc_conn_parameters *cp,
 699                        struct sockaddr_rxrpc *srx,
 700                        gfp_t gfp)
 701 {
 702         struct rxrpc_bundle *bundle;
 703         struct rxrpc_net *rxnet = cp->local->rxnet;
 704         int ret = 0;
 705
 706         _enter("{%d,%lx},", call->debug_id, call->user_call_ID);
 707
 708         rxrpc_discard_expired_client_conns(&rxnet->client_conn_reaper);
 709
 710         bundle = rxrpc_prep_call(rx, call, cp, srx, gfp);
 711         if (IS_ERR(bundle)) {
 712                 ret = PTR_ERR(bundle);
 713                 goto out;
 714         }
 715
 716         if (call->state == RXRPC_CALL_CLIENT_AWAIT_CONN) {
 717                 ret = rxrpc_wait_for_channel(bundle, call, gfp);
 718                 if (ret < 0)
 719                         goto wait_failed;
 720         }
 721
 722 granted_channel:
 723         /* Paired with the write barrier in rxrpc_activate_one_channel(). */
 724         smp_rmb();
 725
 726 out_put_bundle:
 727         rxrpc_put_bundle(bundle);
 728 out:
 729         _leave(" = %d", ret);
 730         return ret;
 731
 732 wait_failed:
 733         spin_lock(&bundle->channel_lock);
 734         list_del_init(&call->chan_wait_link);
 735         spin_unlock(&bundle->channel_lock);
 736
 737         if (call->state != RXRPC_CALL_CLIENT_AWAIT_CONN) {
 738                 ret = 0;
 739                 goto granted_channel;
 740         }
 741
 742         trace_rxrpc_client(call->conn, ret, rxrpc_client_chan_wait_failed);
 743         rxrpc_set_call_completion(call, RXRPC_CALL_LOCAL_ERROR, 0, ret);
 744         rxrpc_disconnect_client_call(bundle, call);
 745         goto out_put_bundle;
 746 }
 747
 748 /*
 749  * Note that a call, and thus a connection, is about to be exposed to the
 750  * world.
 751  */
 752 void rxrpc_expose_client_call(struct rxrpc_call *call)
 753 {
 754         unsigned int channel = call->cid & RXRPC_CHANNELMASK;
 755         struct rxrpc_connection *conn = call->conn;
 756         struct rxrpc_channel *chan = &conn->channels[channel];
 757
 758         if (!test_and_set_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 759                 /* Mark the call ID as being used.  If the callNumber counter
 760                  * exceeds ~2 billion, we kill the connection after its
 761                  * outstanding calls have finished so that the counter doesn't
 762                  * wrap.
 763                  */
 764                 chan->call_counter++;
 765                 if (chan->call_counter >= INT_MAX)
 766                         set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
 767                 trace_rxrpc_client(conn, channel, rxrpc_client_exposed);
 768         }
 769 }
 770
 771 /*
 772  * Set the reap timer.
 773  */
 774 static void rxrpc_set_client_reap_timer(struct rxrpc_net *rxnet)
 775 {
 776         if (!rxnet->kill_all_client_conns) {
 777                 unsigned long now = jiffies;
 778                 unsigned long reap_at = now + rxrpc_conn_idle_client_expiry;
 779
 780                 if (rxnet->live)
 781                         timer_reduce(&rxnet->client_conn_reap_timer, reap_at);
 782         }
 783 }
 784
 785 /*
 786  * Disconnect a client call.
 787  */
 788 void rxrpc_disconnect_client_call(struct rxrpc_bundle *bundle, struct rxrpc_call *call)
 789 {
 790         struct rxrpc_connection *conn;
 791         struct rxrpc_channel *chan = NULL;
 792         struct rxrpc_net *rxnet = bundle->params.local->rxnet;
 793         unsigned int channel;
 794         bool may_reuse;
 795         u32 cid;
 796
 797         _enter("c=%x", call->debug_id);
 798
 799         spin_lock(&bundle->channel_lock);
 800         set_bit(RXRPC_CALL_DISCONNECTED, &call->flags);
 801
 802         /* Calls that have never actually been assigned a channel can simply be
 803          * discarded.
 804          */
 805         conn = call->conn;
 806         if (!conn) {
 807                 _debug("call is waiting");
 808                 ASSERTCMP(call->call_id, ==, 0);
 809                 ASSERT(!test_bit(RXRPC_CALL_EXPOSED, &call->flags));
 810                 list_del_init(&call->chan_wait_link);
 811                 goto out;
 812         }
 813
 814         cid = call->cid;
 815         channel = cid & RXRPC_CHANNELMASK;
 816         chan = &conn->channels[channel];
 817         trace_rxrpc_client(conn, channel, rxrpc_client_chan_disconnect);
 818
 819         if (rcu_access_pointer(chan->call) != call) {
 820                 spin_unlock(&bundle->channel_lock);
 821                 BUG();
 822         }
 823
 824         may_reuse = rxrpc_may_reuse_conn(conn);
 825
 826         /* If a client call was exposed to the world, we save the result for
 827          * retransmission.
 828          *
 829          * We use a barrier here so that the call number and abort code can be
 830          * read without needing to take a lock.
 831          *
 832          * TODO: Make the incoming packet handler check this and handle
 833          * terminal retransmission without requiring access to the call.
 834          */
 835         if (test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 836                 _debug("exposed %u,%u", call->call_id, call->abort_code);
 837                 __rxrpc_disconnect_call(conn, call);
 838
 839                 if (test_and_clear_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags)) {
 840                         trace_rxrpc_client(conn, channel, rxrpc_client_to_active);
 841                         bundle->try_upgrade = false;
 842                         if (may_reuse)
 843                                 rxrpc_activate_channels_locked(bundle);
 844                 }
 845
 846         }
 847
 848         /* See if we can pass the channel directly to another call. */
 849         if (may_reuse && !list_empty(&bundle->waiting_calls)) {
 850                 trace_rxrpc_client(conn, channel, rxrpc_client_chan_pass);
 851                 rxrpc_activate_one_channel(conn, channel);
 852                 goto out;
 853         }
 854
 855         /* Schedule the final ACK to be transmitted in a short while so that it
 856          * can be skipped if we find a follow-on call.  The first DATA packet
 857          * of the follow on call will implicitly ACK this call.
 858          */
 859         if (call->completion == RXRPC_CALL_SUCCEEDED &&
 860             test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 861                 unsigned long final_ack_at = jiffies + 2;
 862
 863                 WRITE_ONCE(chan->final_ack_at, final_ack_at);
 864                 smp_wmb(); /* vs rxrpc_process_delayed_final_acks() */
 865                 set_bit(RXRPC_CONN_FINAL_ACK_0 + channel, &conn->flags);
 866                 rxrpc_reduce_conn_timer(conn, final_ack_at);
 867         }
 868
 869         /* Deactivate the channel. */
 870         rcu_assign_pointer(chan->call, NULL);
 871         set_bit(conn->bundle_shift + channel, &conn->bundle->avail_chans);
 872         conn->act_chans &= ~(1 << channel);
 873
 874         /* If no channels remain active, then put the connection on the idle
 875          * list for a short while.  Give it a ref to stop it going away if it
 876          * becomes unbundled.
 877          */
 878         if (!conn->act_chans) {
 879                 trace_rxrpc_client(conn, channel, rxrpc_client_to_idle);
 880                 conn->idle_timestamp = jiffies;
 881
 882                 rxrpc_get_connection(conn);
 883                 spin_lock(&rxnet->client_conn_cache_lock);
 884                 list_move_tail(&conn->cache_link, &rxnet->idle_client_conns);
 885                 spin_unlock(&rxnet->client_conn_cache_lock);
 886
 887                 rxrpc_set_client_reap_timer(rxnet);
 888         }
 889
 890 out:
 891         spin_unlock(&bundle->channel_lock);
 892         _leave("");
 893         return;
 894 }
 895
 896 /*
 897  * Remove a connection from a bundle.
 898  */
 899 static void rxrpc_unbundle_conn(struct rxrpc_connection *conn)
 900 {
 901         struct rxrpc_bundle *bundle = conn->bundle;
 902         struct rxrpc_local *local = bundle->params.local;
 903         unsigned int bindex;
 904         bool need_drop = false, need_put = false;
 905         int i;
 906
 907         _enter("C=%x", conn->debug_id);
 908
 909         if (conn->flags & RXRPC_CONN_FINAL_ACK_MASK)
 910                 rxrpc_process_delayed_final_acks(conn, true);
 911
 912         spin_lock(&bundle->channel_lock);
 913         bindex = conn->bundle_shift / RXRPC_MAXCALLS;
 914         if (bundle->conns[bindex] == conn) {
 915                 _debug("clear slot %u", bindex);
 916                 bundle->conns[bindex] = NULL;
 917                 for (i = 0; i < RXRPC_MAXCALLS; i++)
 918                         clear_bit(conn->bundle_shift + i, &bundle->avail_chans);
 919                 need_drop = true;
 920         }
 921         spin_unlock(&bundle->channel_lock);
 922
 923         /* If there are no more connections, remove the bundle */
 924         if (!bundle->avail_chans) {
 925                 _debug("maybe unbundle");
 926                 spin_lock(&local->client_bundles_lock);
 927
 928                 for (i = 0; i < ARRAY_SIZE(bundle->conns); i++)
 929                         if (bundle->conns[i])
 930                                 break;
 931                 if (i == ARRAY_SIZE(bundle->conns) && !bundle->params.exclusive) {
 932                         _debug("erase bundle");
 933                         rb_erase(&bundle->local_node, &local->client_bundles);
 934                         need_put = true;
 935                 }
 936
 937                 spin_unlock(&local->client_bundles_lock);
 938                 if (need_put)
 939                         rxrpc_put_bundle(bundle);
 940         }
 941
 942         if (need_drop)
 943                 rxrpc_put_connection(conn);
 944         _leave("");
 945 }
 946
 947 /*
 948  * Clean up a dead client connection.
 949  */
 950 static void rxrpc_kill_client_conn(struct rxrpc_connection *conn)
 951 {
 952         struct rxrpc_local *local = conn->params.local;
 953         struct rxrpc_net *rxnet = local->rxnet;
 954
 955         _enter("C=%x", conn->debug_id);
 956
 957         trace_rxrpc_client(conn, -1, rxrpc_client_cleanup);
 958         atomic_dec(&rxnet->nr_client_conns);
 959
 960         rxrpc_put_client_connection_id(conn);
 961         rxrpc_kill_connection(conn);
 962 }
 963
 964 /*
 965  * Clean up a dead client connections.
 966  */
 967 void rxrpc_put_client_conn(struct rxrpc_connection *conn)
 968 {
 969         const void *here = __builtin_return_address(0);
 970         unsigned int debug_id = conn->debug_id;
 971         int n;
 972
 973         n = atomic_dec_return(&conn->usage);
 974         trace_rxrpc_conn(debug_id, rxrpc_conn_put_client, n, here);
 975         if (n <= 0) {
 976                 ASSERTCMP(n, >=, 0);
 977                 rxrpc_kill_client_conn(conn);
 978         }
 979 }
 980
 981 /*
 982  * Discard expired client connections from the idle list.  Each conn in the
 983  * idle list has been exposed and holds an extra ref because of that.
 984  *
 985  * This may be called from conn setup or from a work item so cannot be
 986  * considered non-reentrant.
 987  */
 988 void rxrpc_discard_expired_client_conns(struct work_struct *work)
 989 {
 990         struct rxrpc_connection *conn;
 991         struct rxrpc_net *rxnet =
 992                 container_of(work, struct rxrpc_net, client_conn_reaper);
 993         unsigned long expiry, conn_expires_at, now;
 994         unsigned int nr_conns;
 995
 996         _enter("");
 997
 998         if (list_empty(&rxnet->idle_client_conns)) {
 999                 _leave(" [empty]");
1000                 return;
1001         }
1002
1003         /* Don't double up on the discarding */
1004         if (!spin_trylock(&rxnet->client_conn_discard_lock)) {
1005                 _leave(" [already]");
1006                 return;
1007         }
1008
1009         /* We keep an estimate of what the number of conns ought to be after
1010          * we've discarded some so that we don't overdo the discarding.
1011          */
1012         nr_conns = atomic_read(&rxnet->nr_client_conns);
1013
1014 next:
1015         spin_lock(&rxnet->client_conn_cache_lock);
1016
1017         if (list_empty(&rxnet->idle_client_conns))
1018                 goto out;
1019
1020         conn = list_entry(rxnet->idle_client_conns.next,
1021                           struct rxrpc_connection, cache_link);
1022
1023         if (!rxnet->kill_all_client_conns) {
1024                 /* If the number of connections is over the reap limit, we
1025                  * expedite discard by reducing the expiry timeout.  We must,
1026                  * however, have at least a short grace period to be able to do
1027                  * final-ACK or ABORT retransmission.
1028                  */
1029                 expiry = rxrpc_conn_idle_client_expiry;
1030                 if (nr_conns > rxrpc_reap_client_connections)
1031                         expiry = rxrpc_conn_idle_client_fast_expiry;
1032                 if (conn->params.local->service_closed)
1033                         expiry = rxrpc_closed_conn_expiry * HZ;
1034
1035                 conn_expires_at = conn->idle_timestamp + expiry;
1036
1037                 now = READ_ONCE(jiffies);
1038                 if (time_after(conn_expires_at, now))
1039                         goto not_yet_expired;
1040         }
1041
1042         trace_rxrpc_client(conn, -1, rxrpc_client_discard);
1043         list_del_init(&conn->cache_link);
1044
1045         spin_unlock(&rxnet->client_conn_cache_lock);
1046
1047         rxrpc_unbundle_conn(conn);
1048         rxrpc_put_connection(conn); /* Drop the ->cache_link ref */
1049
1050         nr_conns--;
1051         goto next;
1052
1053 not_yet_expired:
1054         /* The connection at the front of the queue hasn't yet expired, so
1055          * schedule the work item for that point if we discarded something.
1056          *
1057          * We don't worry if the work item is already scheduled - it can look
1058          * after rescheduling itself at a later time.  We could cancel it, but
1059          * then things get messier.
1060          */
1061         _debug("not yet");
1062         if (!rxnet->kill_all_client_conns)
1063                 timer_reduce(&rxnet->client_conn_reap_timer, conn_expires_at);
1064
1065 out:
1066         spin_unlock(&rxnet->client_conn_cache_lock);
1067         spin_unlock(&rxnet->client_conn_discard_lock);
1068         _leave("");
1069 }
1070
1071 /*
1072  * Preemptively destroy all the client connection records rather than waiting
1073  * for them to time out
1074  */
1075 void rxrpc_destroy_all_client_connections(struct rxrpc_net *rxnet)
1076 {
1077         _enter("");
1078
1079         spin_lock(&rxnet->client_conn_cache_lock);
1080         rxnet->kill_all_client_conns = true;
1081         spin_unlock(&rxnet->client_conn_cache_lock);
1082
1083         del_timer_sync(&rxnet->client_conn_reap_timer);
1084
1085         if (!rxrpc_queue_work(&rxnet->client_conn_reaper))
1086                 _debug("destroy: queue failed");
1087
1088         _leave("");
1089 }
1090
1091 /*
1092  * Clean up the client connections on a local endpoint.
1093  */
1094 void rxrpc_clean_up_local_conns(struct rxrpc_local *local)
1095 {
1096         struct rxrpc_connection *conn, *tmp;
1097         struct rxrpc_net *rxnet = local->rxnet;
1098         LIST_HEAD(graveyard);
1099
1100         _enter("");
1101
1102         spin_lock(&rxnet->client_conn_cache_lock);
1103
1104         list_for_each_entry_safe(conn, tmp, &rxnet->idle_client_conns,
1105                                  cache_link) {
1106                 if (conn->params.local == local) {
1107                         trace_rxrpc_client(conn, -1, rxrpc_client_discard);
1108                         list_move(&conn->cache_link, &graveyard);
1109                 }
1110         }
1111
1112         spin_unlock(&rxnet->client_conn_cache_lock);
1113
1114         while (!list_empty(&graveyard)) {
1115                 conn = list_entry(graveyard.next,
1116                                   struct rxrpc_connection, cache_link);
1117                 list_del_init(&conn->cache_link);
1118                 rxrpc_unbundle_conn(conn);
1119                 rxrpc_put_connection(conn);
1120         }
1121
1122         _leave(" [culled]");
1123 }