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