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 static void rxrpc_free_bundle(struct rxrpc_bundle *bundle)
 139 {
 140         rxrpc_put_peer(bundle->params.peer);
 141         kfree(bundle);
 142 }
 143
 144 void rxrpc_put_bundle(struct rxrpc_bundle *bundle)
 145 {
 146         unsigned int d = bundle->debug_id;
 147         unsigned int u = atomic_dec_return(&bundle->usage);
 148
 149         _debug("PUT B=%x %u", d, u);
 150         if (u == 0)
 151                 rxrpc_free_bundle(bundle);
 152 }
 153
 154 /*
 155  * Allocate a client connection.
 156  */
 157 static struct rxrpc_connection *
 158 rxrpc_alloc_client_connection(struct rxrpc_bundle *bundle, gfp_t gfp)
 159 {
 160         struct rxrpc_connection *conn;
 161         struct rxrpc_net *rxnet = bundle->params.local->rxnet;
 162         int ret;
 163
 164         _enter("");
 165
 166         conn = rxrpc_alloc_connection(gfp);
 167         if (!conn) {
 168                 _leave(" = -ENOMEM");
 169                 return ERR_PTR(-ENOMEM);
 170         }
 171
 172         atomic_set(&conn->usage, 1);
 173         conn->bundle            = bundle;
 174         conn->params            = bundle->params;
 175         conn->out_clientflag    = RXRPC_CLIENT_INITIATED;
 176         conn->state             = RXRPC_CONN_CLIENT;
 177         conn->service_id        = conn->params.service_id;
 178
 179         ret = rxrpc_get_client_connection_id(conn, gfp);
 180         if (ret < 0)
 181                 goto error_0;
 182
 183         ret = rxrpc_init_client_conn_security(conn);
 184         if (ret < 0)
 185                 goto error_1;
 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_1:
 207         rxrpc_put_client_connection_id(conn);
 208 error_0:
 209         kfree(conn);
 210         _leave(" = %d", ret);
 211         return ERR_PTR(ret);
 212 }
 213
 214 /*
 215  * Determine if a connection may be reused.
 216  */
 217 static bool rxrpc_may_reuse_conn(struct rxrpc_connection *conn)
 218 {
 219         struct rxrpc_net *rxnet;
 220         int id_cursor, id, distance, limit;
 221
 222         if (!conn)
 223                 goto dont_reuse;
 224
 225         rxnet = conn->params.local->rxnet;
 226         if (test_bit(RXRPC_CONN_DONT_REUSE, &conn->flags))
 227                 goto dont_reuse;
 228
 229         if (conn->state != RXRPC_CONN_CLIENT ||
 230             conn->proto.epoch != rxnet->epoch)
 231                 goto mark_dont_reuse;
 232
 233         /* The IDR tree gets very expensive on memory if the connection IDs are
 234          * widely scattered throughout the number space, so we shall want to
 235          * kill off connections that, say, have an ID more than about four
 236          * times the maximum number of client conns away from the current
 237          * allocation point to try and keep the IDs concentrated.
 238          */
 239         id_cursor = idr_get_cursor(&rxrpc_client_conn_ids);
 240         id = conn->proto.cid >> RXRPC_CIDSHIFT;
 241         distance = id - id_cursor;
 242         if (distance < 0)
 243                 distance = -distance;
 244         limit = max_t(unsigned long, atomic_read(&rxnet->nr_conns) * 4, 1024);
 245         if (distance > limit)
 246                 goto mark_dont_reuse;
 247
 248         return true;
 249
 250 mark_dont_reuse:
 251         set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
 252 dont_reuse:
 253         return false;
 254 }
 255
 256 /*
 257  * Look up the conn bundle that matches the connection parameters, adding it if
 258  * it doesn't yet exist.
 259  */
 260 static struct rxrpc_bundle *rxrpc_look_up_bundle(struct rxrpc_conn_parameters *cp,
 261                                                  gfp_t gfp)
 262 {
 263         static atomic_t rxrpc_bundle_id;
 264         struct rxrpc_bundle *bundle, *candidate;
 265         struct rxrpc_local *local = cp->local;
 266         struct rb_node *p, **pp, *parent;
 267         long diff;
 268
 269         _enter("{%px,%x,%u,%u}",
 270                cp->peer, key_serial(cp->key), cp->security_level, cp->upgrade);
 271
 272         if (cp->exclusive)
 273                 return rxrpc_alloc_bundle(cp, gfp);
 274
 275         /* First, see if the bundle is already there. */
 276         _debug("search 1");
 277         spin_lock(&local->client_bundles_lock);
 278         p = local->client_bundles.rb_node;
 279         while (p) {
 280                 bundle = rb_entry(p, struct rxrpc_bundle, local_node);
 281
 282 #define cmp(X) ((long)bundle->params.X - (long)cp->X)
 283                 diff = (cmp(peer) ?:
 284                         cmp(key) ?:
 285                         cmp(security_level) ?:
 286                         cmp(upgrade));
 287 #undef cmp
 288                 if (diff < 0)
 289                         p = p->rb_left;
 290                 else if (diff > 0)
 291                         p = p->rb_right;
 292                 else
 293                         goto found_bundle;
 294         }
 295         spin_unlock(&local->client_bundles_lock);
 296         _debug("not found");
 297
 298         /* It wasn't.  We need to add one. */
 299         candidate = rxrpc_alloc_bundle(cp, gfp);
 300         if (!candidate)
 301                 return NULL;
 302
 303         _debug("search 2");
 304         spin_lock(&local->client_bundles_lock);
 305         pp = &local->client_bundles.rb_node;
 306         parent = NULL;
 307         while (*pp) {
 308                 parent = *pp;
 309                 bundle = rb_entry(parent, struct rxrpc_bundle, local_node);
 310
 311 #define cmp(X) ((long)bundle->params.X - (long)cp->X)
 312                 diff = (cmp(peer) ?:
 313                         cmp(key) ?:
 314                         cmp(security_level) ?:
 315                         cmp(upgrade));
 316 #undef cmp
 317                 if (diff < 0)
 318                         pp = &(*pp)->rb_left;
 319                 else if (diff > 0)
 320                         pp = &(*pp)->rb_right;
 321                 else
 322                         goto found_bundle_free;
 323         }
 324
 325         _debug("new bundle");
 326         candidate->debug_id = atomic_inc_return(&rxrpc_bundle_id);
 327         rb_link_node(&candidate->local_node, parent, pp);
 328         rb_insert_color(&candidate->local_node, &local->client_bundles);
 329         rxrpc_get_bundle(candidate);
 330         spin_unlock(&local->client_bundles_lock);
 331         _leave(" = %u [new]", candidate->debug_id);
 332         return candidate;
 333
 334 found_bundle_free:
 335         rxrpc_free_bundle(candidate);
 336 found_bundle:
 337         rxrpc_get_bundle(bundle);
 338         spin_unlock(&local->client_bundles_lock);
 339         _leave(" = %u [found]", bundle->debug_id);
 340         return bundle;
 341 }
 342
 343 /*
 344  * Create or find a client bundle to use for a call.
 345  *
 346  * If we return with a connection, the call will be on its waiting list.  It's
 347  * left to the caller to assign a channel and wake up the call.
 348  */
 349 static struct rxrpc_bundle *rxrpc_prep_call(struct rxrpc_sock *rx,
 350                                             struct rxrpc_call *call,
 351                                             struct rxrpc_conn_parameters *cp,
 352                                             struct sockaddr_rxrpc *srx,
 353                                             gfp_t gfp)
 354 {
 355         struct rxrpc_bundle *bundle;
 356
 357         _enter("{%d,%lx},", call->debug_id, call->user_call_ID);
 358
 359         cp->peer = rxrpc_lookup_peer(rx, cp->local, srx, gfp);
 360         if (!cp->peer)
 361                 goto error;
 362
 363         call->cong_cwnd = cp->peer->cong_cwnd;
 364         if (call->cong_cwnd >= call->cong_ssthresh)
 365                 call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
 366         else
 367                 call->cong_mode = RXRPC_CALL_SLOW_START;
 368         if (cp->upgrade)
 369                 __set_bit(RXRPC_CALL_UPGRADE, &call->flags);
 370
 371         /* Find the client connection bundle. */
 372         bundle = rxrpc_look_up_bundle(cp, gfp);
 373         if (!bundle)
 374                 goto error;
 375
 376         /* Get this call queued.  Someone else may activate it whilst we're
 377          * lining up a new connection, but that's fine.
 378          */
 379         spin_lock(&bundle->channel_lock);
 380         list_add_tail(&call->chan_wait_link, &bundle->waiting_calls);
 381         spin_unlock(&bundle->channel_lock);
 382
 383         _leave(" = [B=%x]", bundle->debug_id);
 384         return bundle;
 385
 386 error:
 387         _leave(" = -ENOMEM");
 388         return ERR_PTR(-ENOMEM);
 389 }
 390
 391 /*
 392  * Allocate a new connection and add it into a bundle.
 393  */
 394 static void rxrpc_add_conn_to_bundle(struct rxrpc_bundle *bundle, gfp_t gfp)
 395         __releases(bundle->channel_lock)
 396 {
 397         struct rxrpc_connection *candidate = NULL, *old = NULL;
 398         bool conflict;
 399         int i;
 400
 401         _enter("");
 402
 403         conflict = bundle->alloc_conn;
 404         if (!conflict)
 405                 bundle->alloc_conn = true;
 406         spin_unlock(&bundle->channel_lock);
 407         if (conflict) {
 408                 _leave(" [conf]");
 409                 return;
 410         }
 411
 412         candidate = rxrpc_alloc_client_connection(bundle, gfp);
 413
 414         spin_lock(&bundle->channel_lock);
 415         bundle->alloc_conn = false;
 416
 417         if (IS_ERR(candidate)) {
 418                 bundle->alloc_error = PTR_ERR(candidate);
 419                 spin_unlock(&bundle->channel_lock);
 420                 _leave(" [err %ld]", PTR_ERR(candidate));
 421                 return;
 422         }
 423
 424         bundle->alloc_error = 0;
 425
 426         for (i = 0; i < ARRAY_SIZE(bundle->conns); i++) {
 427                 unsigned int shift = i * RXRPC_MAXCALLS;
 428                 int j;
 429
 430                 old = bundle->conns[i];
 431                 if (!rxrpc_may_reuse_conn(old)) {
 432                         if (old)
 433                                 trace_rxrpc_client(old, -1, rxrpc_client_replace);
 434                         candidate->bundle_shift = shift;
 435                         bundle->conns[i] = candidate;
 436                         for (j = 0; j < RXRPC_MAXCALLS; j++)
 437                                 set_bit(shift + j, &bundle->avail_chans);
 438                         candidate = NULL;
 439                         break;
 440                 }
 441
 442                 old = NULL;
 443         }
 444
 445         spin_unlock(&bundle->channel_lock);
 446
 447         if (candidate) {
 448                 _debug("discard C=%x", candidate->debug_id);
 449                 trace_rxrpc_client(candidate, -1, rxrpc_client_duplicate);
 450                 rxrpc_put_connection(candidate);
 451         }
 452
 453         rxrpc_put_connection(old);
 454         _leave("");
 455 }
 456
 457 /*
 458  * Add a connection to a bundle if there are no usable connections or we have
 459  * connections waiting for extra capacity.
 460  */
 461 static void rxrpc_maybe_add_conn(struct rxrpc_bundle *bundle, gfp_t gfp)
 462 {
 463         struct rxrpc_call *call;
 464         int i, usable;
 465
 466         _enter("");
 467
 468         spin_lock(&bundle->channel_lock);
 469
 470         /* See if there are any usable connections. */
 471         usable = 0;
 472         for (i = 0; i < ARRAY_SIZE(bundle->conns); i++)
 473                 if (rxrpc_may_reuse_conn(bundle->conns[i]))
 474                         usable++;
 475
 476         if (!usable && !list_empty(&bundle->waiting_calls)) {
 477                 call = list_first_entry(&bundle->waiting_calls,
 478                                         struct rxrpc_call, chan_wait_link);
 479                 if (test_bit(RXRPC_CALL_UPGRADE, &call->flags))
 480                         bundle->try_upgrade = true;
 481         }
 482
 483         if (!usable)
 484                 goto alloc_conn;
 485
 486         if (!bundle->avail_chans &&
 487             !bundle->try_upgrade &&
 488             !list_empty(&bundle->waiting_calls) &&
 489             usable < ARRAY_SIZE(bundle->conns))
 490                 goto alloc_conn;
 491
 492         spin_unlock(&bundle->channel_lock);
 493         _leave("");
 494         return;
 495
 496 alloc_conn:
 497         return rxrpc_add_conn_to_bundle(bundle, gfp);
 498 }
 499
 500 /*
 501  * Assign a channel to the call at the front of the queue and wake the call up.
 502  * We don't increment the callNumber counter until this number has been exposed
 503  * to the world.
 504  */
 505 static void rxrpc_activate_one_channel(struct rxrpc_connection *conn,
 506                                        unsigned int channel)
 507 {
 508         struct rxrpc_channel *chan = &conn->channels[channel];
 509         struct rxrpc_bundle *bundle = conn->bundle;
 510         struct rxrpc_call *call = list_entry(bundle->waiting_calls.next,
 511                                              struct rxrpc_call, chan_wait_link);
 512         u32 call_id = chan->call_counter + 1;
 513
 514         _enter("C=%x,%u", conn->debug_id, channel);
 515
 516         trace_rxrpc_client(conn, channel, rxrpc_client_chan_activate);
 517
 518         /* Cancel the final ACK on the previous call if it hasn't been sent yet
 519          * as the DATA packet will implicitly ACK it.
 520          */
 521         clear_bit(RXRPC_CONN_FINAL_ACK_0 + channel, &conn->flags);
 522         clear_bit(conn->bundle_shift + channel, &bundle->avail_chans);
 523
 524         rxrpc_see_call(call);
 525         list_del_init(&call->chan_wait_link);
 526         call->peer      = rxrpc_get_peer(conn->params.peer);
 527         call->conn      = rxrpc_get_connection(conn);
 528         call->cid       = conn->proto.cid | channel;
 529         call->call_id   = call_id;
 530         call->security  = conn->security;
 531         call->security_ix = conn->security_ix;
 532         call->service_id = conn->service_id;
 533
 534         trace_rxrpc_connect_call(call);
 535         _net("CONNECT call %08x:%08x as call %d on conn %d",
 536              call->cid, call->call_id, call->debug_id, conn->debug_id);
 537
 538         write_lock_bh(&call->state_lock);
 539         call->state = RXRPC_CALL_CLIENT_SEND_REQUEST;
 540         write_unlock_bh(&call->state_lock);
 541
 542         /* Paired with the read barrier in rxrpc_connect_call().  This orders
 543          * cid and epoch in the connection wrt to call_id without the need to
 544          * take the channel_lock.
 545          *
 546          * We provisionally assign a callNumber at this point, but we don't
 547          * confirm it until the call is about to be exposed.
 548          *
 549          * TODO: Pair with a barrier in the data_ready handler when that looks
 550          * at the call ID through a connection channel.
 551          */
 552         smp_wmb();
 553
 554         chan->call_id           = call_id;
 555         chan->call_debug_id     = call->debug_id;
 556         rcu_assign_pointer(chan->call, call);
 557         wake_up(&call->waitq);
 558 }
 559
 560 /*
 561  * Remove a connection from the idle list if it's on it.
 562  */
 563 static void rxrpc_unidle_conn(struct rxrpc_bundle *bundle, struct rxrpc_connection *conn)
 564 {
 565         struct rxrpc_net *rxnet = bundle->params.local->rxnet;
 566         bool drop_ref;
 567
 568         if (!list_empty(&conn->cache_link)) {
 569                 drop_ref = false;
 570                 spin_lock(&rxnet->client_conn_cache_lock);
 571                 if (!list_empty(&conn->cache_link)) {
 572                         list_del_init(&conn->cache_link);
 573                         drop_ref = true;
 574                 }
 575                 spin_unlock(&rxnet->client_conn_cache_lock);
 576                 if (drop_ref)
 577                         rxrpc_put_connection(conn);
 578         }
 579 }
 580
 581 /*
 582  * Assign channels and callNumbers to waiting calls with channel_lock
 583  * held by caller.
 584  */
 585 static void rxrpc_activate_channels_locked(struct rxrpc_bundle *bundle)
 586 {
 587         struct rxrpc_connection *conn;
 588         unsigned long avail, mask;
 589         unsigned int channel, slot;
 590
 591         if (bundle->try_upgrade)
 592                 mask = 1;
 593         else
 594                 mask = ULONG_MAX;
 595
 596         while (!list_empty(&bundle->waiting_calls)) {
 597                 avail = bundle->avail_chans & mask;
 598                 if (!avail)
 599                         break;
 600                 channel = __ffs(avail);
 601                 clear_bit(channel, &bundle->avail_chans);
 602
 603                 slot = channel / RXRPC_MAXCALLS;
 604                 conn = bundle->conns[slot];
 605                 if (!conn)
 606                         break;
 607
 608                 if (bundle->try_upgrade)
 609                         set_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags);
 610                 rxrpc_unidle_conn(bundle, conn);
 611
 612                 channel &= (RXRPC_MAXCALLS - 1);
 613                 conn->act_chans |= 1 << channel;
 614                 rxrpc_activate_one_channel(conn, channel);
 615         }
 616 }
 617
 618 /*
 619  * Assign channels and callNumbers to waiting calls.
 620  */
 621 static void rxrpc_activate_channels(struct rxrpc_bundle *bundle)
 622 {
 623         _enter("B=%x", bundle->debug_id);
 624
 625         trace_rxrpc_client(NULL, -1, rxrpc_client_activate_chans);
 626
 627         if (!bundle->avail_chans)
 628                 return;
 629
 630         spin_lock(&bundle->channel_lock);
 631         rxrpc_activate_channels_locked(bundle);
 632         spin_unlock(&bundle->channel_lock);
 633         _leave("");
 634 }
 635
 636 /*
 637  * Wait for a callNumber and a channel to be granted to a call.
 638  */
 639 static int rxrpc_wait_for_channel(struct rxrpc_bundle *bundle,
 640                                   struct rxrpc_call *call, gfp_t gfp)
 641 {
 642         DECLARE_WAITQUEUE(myself, current);
 643         int ret = 0;
 644
 645         _enter("%d", call->debug_id);
 646
 647         if (!gfpflags_allow_blocking(gfp)) {
 648                 rxrpc_maybe_add_conn(bundle, gfp);
 649                 rxrpc_activate_channels(bundle);
 650                 ret = bundle->alloc_error ?: -EAGAIN;
 651                 goto out;
 652         }
 653
 654         add_wait_queue_exclusive(&call->waitq, &myself);
 655         for (;;) {
 656                 rxrpc_maybe_add_conn(bundle, gfp);
 657                 rxrpc_activate_channels(bundle);
 658                 ret = bundle->alloc_error;
 659                 if (ret < 0)
 660                         break;
 661
 662                 switch (call->interruptibility) {
 663                 case RXRPC_INTERRUPTIBLE:
 664                 case RXRPC_PREINTERRUPTIBLE:
 665                         set_current_state(TASK_INTERRUPTIBLE);
 666                         break;
 667                 case RXRPC_UNINTERRUPTIBLE:
 668                 default:
 669                         set_current_state(TASK_UNINTERRUPTIBLE);
 670                         break;
 671                 }
 672                 if (READ_ONCE(call->state) != RXRPC_CALL_CLIENT_AWAIT_CONN)
 673                         break;
 674                 if ((call->interruptibility == RXRPC_INTERRUPTIBLE ||
 675                      call->interruptibility == RXRPC_PREINTERRUPTIBLE) &&
 676                     signal_pending(current)) {
 677                         ret = -ERESTARTSYS;
 678                         break;
 679                 }
 680                 schedule();
 681         }
 682         remove_wait_queue(&call->waitq, &myself);
 683         __set_current_state(TASK_RUNNING);
 684
 685 out:
 686         _leave(" = %d", ret);
 687         return ret;
 688 }
 689
 690 /*
 691  * find a connection for a call
 692  * - called in process context with IRQs enabled
 693  */
 694 int rxrpc_connect_call(struct rxrpc_sock *rx,
 695                        struct rxrpc_call *call,
 696                        struct rxrpc_conn_parameters *cp,
 697                        struct sockaddr_rxrpc *srx,
 698                        gfp_t gfp)
 699 {
 700         struct rxrpc_bundle *bundle;
 701         struct rxrpc_net *rxnet = cp->local->rxnet;
 702         int ret = 0;
 703
 704         _enter("{%d,%lx},", call->debug_id, call->user_call_ID);
 705
 706         rxrpc_discard_expired_client_conns(&rxnet->client_conn_reaper);
 707
 708         bundle = rxrpc_prep_call(rx, call, cp, srx, gfp);
 709         if (IS_ERR(bundle)) {
 710                 ret = PTR_ERR(bundle);
 711                 goto out;
 712         }
 713
 714         if (call->state == RXRPC_CALL_CLIENT_AWAIT_CONN) {
 715                 ret = rxrpc_wait_for_channel(bundle, call, gfp);
 716                 if (ret < 0)
 717                         goto wait_failed;
 718         }
 719
 720 granted_channel:
 721         /* Paired with the write barrier in rxrpc_activate_one_channel(). */
 722         smp_rmb();
 723
 724 out_put_bundle:
 725         rxrpc_put_bundle(bundle);
 726 out:
 727         _leave(" = %d", ret);
 728         return ret;
 729
 730 wait_failed:
 731         spin_lock(&bundle->channel_lock);
 732         list_del_init(&call->chan_wait_link);
 733         spin_unlock(&bundle->channel_lock);
 734
 735         if (call->state != RXRPC_CALL_CLIENT_AWAIT_CONN) {
 736                 ret = 0;
 737                 goto granted_channel;
 738         }
 739
 740         trace_rxrpc_client(call->conn, ret, rxrpc_client_chan_wait_failed);
 741         rxrpc_set_call_completion(call, RXRPC_CALL_LOCAL_ERROR, 0, ret);
 742         rxrpc_disconnect_client_call(bundle, call);
 743         goto out_put_bundle;
 744 }
 745
 746 /*
 747  * Note that a call, and thus a connection, is about to be exposed to the
 748  * world.
 749  */
 750 void rxrpc_expose_client_call(struct rxrpc_call *call)
 751 {
 752         unsigned int channel = call->cid & RXRPC_CHANNELMASK;
 753         struct rxrpc_connection *conn = call->conn;
 754         struct rxrpc_channel *chan = &conn->channels[channel];
 755
 756         if (!test_and_set_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 757                 /* Mark the call ID as being used.  If the callNumber counter
 758                  * exceeds ~2 billion, we kill the connection after its
 759                  * outstanding calls have finished so that the counter doesn't
 760                  * wrap.
 761                  */
 762                 chan->call_counter++;
 763                 if (chan->call_counter >= INT_MAX)
 764                         set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
 765                 trace_rxrpc_client(conn, channel, rxrpc_client_exposed);
 766         }
 767 }
 768
 769 /*
 770  * Set the reap timer.
 771  */
 772 static void rxrpc_set_client_reap_timer(struct rxrpc_net *rxnet)
 773 {
 774         if (!rxnet->kill_all_client_conns) {
 775                 unsigned long now = jiffies;
 776                 unsigned long reap_at = now + rxrpc_conn_idle_client_expiry;
 777
 778                 if (rxnet->live)
 779                         timer_reduce(&rxnet->client_conn_reap_timer, reap_at);
 780         }
 781 }
 782
 783 /*
 784  * Disconnect a client call.
 785  */
 786 void rxrpc_disconnect_client_call(struct rxrpc_bundle *bundle, struct rxrpc_call *call)
 787 {
 788         struct rxrpc_connection *conn;
 789         struct rxrpc_channel *chan = NULL;
 790         struct rxrpc_net *rxnet = bundle->params.local->rxnet;
 791         unsigned int channel;
 792         bool may_reuse;
 793         u32 cid;
 794
 795         _enter("c=%x", call->debug_id);
 796
 797         spin_lock(&bundle->channel_lock);
 798         set_bit(RXRPC_CALL_DISCONNECTED, &call->flags);
 799
 800         /* Calls that have never actually been assigned a channel can simply be
 801          * discarded.
 802          */
 803         conn = call->conn;
 804         if (!conn) {
 805                 _debug("call is waiting");
 806                 ASSERTCMP(call->call_id, ==, 0);
 807                 ASSERT(!test_bit(RXRPC_CALL_EXPOSED, &call->flags));
 808                 list_del_init(&call->chan_wait_link);
 809                 goto out;
 810         }
 811
 812         cid = call->cid;
 813         channel = cid & RXRPC_CHANNELMASK;
 814         chan = &conn->channels[channel];
 815         trace_rxrpc_client(conn, channel, rxrpc_client_chan_disconnect);
 816
 817         if (rcu_access_pointer(chan->call) != call) {
 818                 spin_unlock(&bundle->channel_lock);
 819                 BUG();
 820         }
 821
 822         may_reuse = rxrpc_may_reuse_conn(conn);
 823
 824         /* If a client call was exposed to the world, we save the result for
 825          * retransmission.
 826          *
 827          * We use a barrier here so that the call number and abort code can be
 828          * read without needing to take a lock.
 829          *
 830          * TODO: Make the incoming packet handler check this and handle
 831          * terminal retransmission without requiring access to the call.
 832          */
 833         if (test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 834                 _debug("exposed %u,%u", call->call_id, call->abort_code);
 835                 __rxrpc_disconnect_call(conn, call);
 836
 837                 if (test_and_clear_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags)) {
 838                         trace_rxrpc_client(conn, channel, rxrpc_client_to_active);
 839                         bundle->try_upgrade = false;
 840                         if (may_reuse)
 841                                 rxrpc_activate_channels_locked(bundle);
 842                 }
 843
 844         }
 845
 846         /* See if we can pass the channel directly to another call. */
 847         if (may_reuse && !list_empty(&bundle->waiting_calls)) {
 848                 trace_rxrpc_client(conn, channel, rxrpc_client_chan_pass);
 849                 rxrpc_activate_one_channel(conn, channel);
 850                 goto out;
 851         }
 852
 853         /* Schedule the final ACK to be transmitted in a short while so that it
 854          * can be skipped if we find a follow-on call.  The first DATA packet
 855          * of the follow on call will implicitly ACK this call.
 856          */
 857         if (call->completion == RXRPC_CALL_SUCCEEDED &&
 858             test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 859                 unsigned long final_ack_at = jiffies + 2;
 860
 861                 WRITE_ONCE(chan->final_ack_at, final_ack_at);
 862                 smp_wmb(); /* vs rxrpc_process_delayed_final_acks() */
 863                 set_bit(RXRPC_CONN_FINAL_ACK_0 + channel, &conn->flags);
 864                 rxrpc_reduce_conn_timer(conn, final_ack_at);
 865         }
 866
 867         /* Deactivate the channel. */
 868         rcu_assign_pointer(chan->call, NULL);
 869         set_bit(conn->bundle_shift + channel, &conn->bundle->avail_chans);
 870         conn->act_chans &= ~(1 << channel);
 871
 872         /* If no channels remain active, then put the connection on the idle
 873          * list for a short while.  Give it a ref to stop it going away if it
 874          * becomes unbundled.
 875          */
 876         if (!conn->act_chans) {
 877                 trace_rxrpc_client(conn, channel, rxrpc_client_to_idle);
 878                 conn->idle_timestamp = jiffies;
 879
 880                 rxrpc_get_connection(conn);
 881                 spin_lock(&rxnet->client_conn_cache_lock);
 882                 list_move_tail(&conn->cache_link, &rxnet->idle_client_conns);
 883                 spin_unlock(&rxnet->client_conn_cache_lock);
 884
 885                 rxrpc_set_client_reap_timer(rxnet);
 886         }
 887
 888 out:
 889         spin_unlock(&bundle->channel_lock);
 890         _leave("");
 891         return;
 892 }
 893
 894 /*
 895  * Remove a connection from a bundle.
 896  */
 897 static void rxrpc_unbundle_conn(struct rxrpc_connection *conn)
 898 {
 899         struct rxrpc_bundle *bundle = conn->bundle;
 900         struct rxrpc_local *local = bundle->params.local;
 901         unsigned int bindex;
 902         bool need_drop = false, need_put = false;
 903         int i;
 904
 905         _enter("C=%x", conn->debug_id);
 906
 907         if (conn->flags & RXRPC_CONN_FINAL_ACK_MASK)
 908                 rxrpc_process_delayed_final_acks(conn, true);
 909
 910         spin_lock(&bundle->channel_lock);
 911         bindex = conn->bundle_shift / RXRPC_MAXCALLS;
 912         if (bundle->conns[bindex] == conn) {
 913                 _debug("clear slot %u", bindex);
 914                 bundle->conns[bindex] = NULL;
 915                 for (i = 0; i < RXRPC_MAXCALLS; i++)
 916                         clear_bit(conn->bundle_shift + i, &bundle->avail_chans);
 917                 need_drop = true;
 918         }
 919         spin_unlock(&bundle->channel_lock);
 920
 921         /* If there are no more connections, remove the bundle */
 922         if (!bundle->avail_chans) {
 923                 _debug("maybe unbundle");
 924                 spin_lock(&local->client_bundles_lock);
 925
 926                 for (i = 0; i < ARRAY_SIZE(bundle->conns); i++)
 927                         if (bundle->conns[i])
 928                                 break;
 929                 if (i == ARRAY_SIZE(bundle->conns) && !bundle->params.exclusive) {
 930                         _debug("erase bundle");
 931                         rb_erase(&bundle->local_node, &local->client_bundles);
 932                         need_put = true;
 933                 }
 934
 935                 spin_unlock(&local->client_bundles_lock);
 936                 if (need_put)
 937                         rxrpc_put_bundle(bundle);
 938         }
 939
 940         if (need_drop)
 941                 rxrpc_put_connection(conn);
 942         _leave("");
 943 }
 944
 945 /*
 946  * Clean up a dead client connection.
 947  */
 948 static void rxrpc_kill_client_conn(struct rxrpc_connection *conn)
 949 {
 950         struct rxrpc_local *local = conn->params.local;
 951         struct rxrpc_net *rxnet = local->rxnet;
 952
 953         _enter("C=%x", conn->debug_id);
 954
 955         trace_rxrpc_client(conn, -1, rxrpc_client_cleanup);
 956         atomic_dec(&rxnet->nr_client_conns);
 957
 958         rxrpc_put_client_connection_id(conn);
 959         rxrpc_kill_connection(conn);
 960 }
 961
 962 /*
 963  * Clean up a dead client connections.
 964  */
 965 void rxrpc_put_client_conn(struct rxrpc_connection *conn)
 966 {
 967         const void *here = __builtin_return_address(0);
 968         unsigned int debug_id = conn->debug_id;
 969         int n;
 970
 971         n = atomic_dec_return(&conn->usage);
 972         trace_rxrpc_conn(debug_id, rxrpc_conn_put_client, n, here);
 973         if (n <= 0) {
 974                 ASSERTCMP(n, >=, 0);
 975                 rxrpc_kill_client_conn(conn);
 976         }
 977 }
 978
 979 /*
 980  * Discard expired client connections from the idle list.  Each conn in the
 981  * idle list has been exposed and holds an extra ref because of that.
 982  *
 983  * This may be called from conn setup or from a work item so cannot be
 984  * considered non-reentrant.
 985  */
 986 void rxrpc_discard_expired_client_conns(struct work_struct *work)
 987 {
 988         struct rxrpc_connection *conn;
 989         struct rxrpc_net *rxnet =
 990                 container_of(work, struct rxrpc_net, client_conn_reaper);
 991         unsigned long expiry, conn_expires_at, now;
 992         unsigned int nr_conns;
 993
 994         _enter("");
 995
 996         if (list_empty(&rxnet->idle_client_conns)) {
 997                 _leave(" [empty]");
 998                 return;
 999         }
1000
1001         /* Don't double up on the discarding */
1002         if (!spin_trylock(&rxnet->client_conn_discard_lock)) {
1003                 _leave(" [already]");
1004                 return;
1005         }
1006
1007         /* We keep an estimate of what the number of conns ought to be after
1008          * we've discarded some so that we don't overdo the discarding.
1009          */
1010         nr_conns = atomic_read(&rxnet->nr_client_conns);
1011
1012 next:
1013         spin_lock(&rxnet->client_conn_cache_lock);
1014
1015         if (list_empty(&rxnet->idle_client_conns))
1016                 goto out;
1017
1018         conn = list_entry(rxnet->idle_client_conns.next,
1019                           struct rxrpc_connection, cache_link);
1020
1021         if (!rxnet->kill_all_client_conns) {
1022                 /* If the number of connections is over the reap limit, we
1023                  * expedite discard by reducing the expiry timeout.  We must,
1024                  * however, have at least a short grace period to be able to do
1025                  * final-ACK or ABORT retransmission.
1026                  */
1027                 expiry = rxrpc_conn_idle_client_expiry;
1028                 if (nr_conns > rxrpc_reap_client_connections)
1029                         expiry = rxrpc_conn_idle_client_fast_expiry;
1030                 if (conn->params.local->service_closed)
1031                         expiry = rxrpc_closed_conn_expiry * HZ;
1032
1033                 conn_expires_at = conn->idle_timestamp + expiry;
1034
1035                 now = READ_ONCE(jiffies);
1036                 if (time_after(conn_expires_at, now))
1037                         goto not_yet_expired;
1038         }
1039
1040         trace_rxrpc_client(conn, -1, rxrpc_client_discard);
1041         list_del_init(&conn->cache_link);
1042
1043         spin_unlock(&rxnet->client_conn_cache_lock);
1044
1045         rxrpc_unbundle_conn(conn);
1046         rxrpc_put_connection(conn); /* Drop the ->cache_link ref */
1047
1048         nr_conns--;
1049         goto next;
1050
1051 not_yet_expired:
1052         /* The connection at the front of the queue hasn't yet expired, so
1053          * schedule the work item for that point if we discarded something.
1054          *
1055          * We don't worry if the work item is already scheduled - it can look
1056          * after rescheduling itself at a later time.  We could cancel it, but
1057          * then things get messier.
1058          */
1059         _debug("not yet");
1060         if (!rxnet->kill_all_client_conns)
1061                 timer_reduce(&rxnet->client_conn_reap_timer, conn_expires_at);
1062
1063 out:
1064         spin_unlock(&rxnet->client_conn_cache_lock);
1065         spin_unlock(&rxnet->client_conn_discard_lock);
1066         _leave("");
1067 }
1068
1069 /*
1070  * Preemptively destroy all the client connection records rather than waiting
1071  * for them to time out
1072  */
1073 void rxrpc_destroy_all_client_connections(struct rxrpc_net *rxnet)
1074 {
1075         _enter("");
1076
1077         spin_lock(&rxnet->client_conn_cache_lock);
1078         rxnet->kill_all_client_conns = true;
1079         spin_unlock(&rxnet->client_conn_cache_lock);
1080
1081         del_timer_sync(&rxnet->client_conn_reap_timer);
1082
1083         if (!rxrpc_queue_work(&rxnet->client_conn_reaper))
1084                 _debug("destroy: queue failed");
1085
1086         _leave("");
1087 }
1088
1089 /*
1090  * Clean up the client connections on a local endpoint.
1091  */
1092 void rxrpc_clean_up_local_conns(struct rxrpc_local *local)
1093 {
1094         struct rxrpc_connection *conn, *tmp;
1095         struct rxrpc_net *rxnet = local->rxnet;
1096         LIST_HEAD(graveyard);
1097
1098         _enter("");
1099
1100         spin_lock(&rxnet->client_conn_cache_lock);
1101
1102         list_for_each_entry_safe(conn, tmp, &rxnet->idle_client_conns,
1103                                  cache_link) {
1104                 if (conn->params.local == local) {
1105                         trace_rxrpc_client(conn, -1, rxrpc_client_discard);
1106                         list_move(&conn->cache_link, &graveyard);
1107                 }
1108         }
1109
1110         spin_unlock(&rxnet->client_conn_cache_lock);
1111
1112         while (!list_empty(&graveyard)) {
1113                 conn = list_entry(graveyard.next,
1114                                   struct rxrpc_connection, cache_link);
1115                 list_del_init(&conn->cache_link);
1116                 rxrpc_unbundle_conn(conn);
1117                 rxrpc_put_connection(conn);
1118         }
1119
1120         _leave(" [culled]");
1121 }