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 static void rxrpc_activate_bundle(struct rxrpc_bundle *bundle)
  38 {
  39         atomic_inc(&bundle->active);
  40 }
  41
  42 /*
  43  * Release a connection ID for a client connection.
  44  */
  45 static void rxrpc_put_client_connection_id(struct rxrpc_local *local,
  46                                            struct rxrpc_connection *conn)
  47 {
  48         idr_remove(&local->conn_ids, conn->proto.cid >> RXRPC_CIDSHIFT);
  49 }
  50
  51 /*
  52  * Destroy the client connection ID tree.
  53  */
  54 static void rxrpc_destroy_client_conn_ids(struct rxrpc_local *local)
  55 {
  56         struct rxrpc_connection *conn;
  57         int id;
  58
  59         if (!idr_is_empty(&local->conn_ids)) {
  60                 idr_for_each_entry(&local->conn_ids, conn, id) {
  61                         pr_err("AF_RXRPC: Leaked client conn %p {%d}\n",
  62                                conn, refcount_read(&conn->ref));
  63                 }
  64                 BUG();
  65         }
  66
  67         idr_destroy(&local->conn_ids);
  68 }
  69
  70 /*
  71  * Allocate a connection bundle.
  72  */
  73 static struct rxrpc_bundle *rxrpc_alloc_bundle(struct rxrpc_call *call,
  74                                                gfp_t gfp)
  75 {
  76         struct rxrpc_bundle *bundle;
  77
  78         bundle = kzalloc(sizeof(*bundle), gfp);
  79         if (bundle) {
  80                 bundle->local           = call->local;
  81                 bundle->peer            = rxrpc_get_peer(call->peer, rxrpc_peer_get_bundle);
  82                 bundle->key             = key_get(call->key);
  83                 bundle->security        = call->security;
  84                 bundle->exclusive       = test_bit(RXRPC_CALL_EXCLUSIVE, &call->flags);
  85                 bundle->upgrade         = test_bit(RXRPC_CALL_UPGRADE, &call->flags);
  86                 bundle->service_id      = call->dest_srx.srx_service;
  87                 bundle->security_level  = call->security_level;
  88                 refcount_set(&bundle->ref, 1);
  89                 atomic_set(&bundle->active, 1);
  90                 INIT_LIST_HEAD(&bundle->waiting_calls);
  91                 trace_rxrpc_bundle(bundle->debug_id, 1, rxrpc_bundle_new);
  92         }
  93         return bundle;
  94 }
  95
  96 struct rxrpc_bundle *rxrpc_get_bundle(struct rxrpc_bundle *bundle,
  97                                       enum rxrpc_bundle_trace why)
  98 {
  99         int r;
 100
 101         __refcount_inc(&bundle->ref, &r);
 102         trace_rxrpc_bundle(bundle->debug_id, r + 1, why);
 103         return bundle;
 104 }
 105
 106 static void rxrpc_free_bundle(struct rxrpc_bundle *bundle)
 107 {
 108         trace_rxrpc_bundle(bundle->debug_id, 1, rxrpc_bundle_free);
 109         rxrpc_put_peer(bundle->peer, rxrpc_peer_put_bundle);
 110         key_put(bundle->key);
 111         kfree(bundle);
 112 }
 113
 114 void rxrpc_put_bundle(struct rxrpc_bundle *bundle, enum rxrpc_bundle_trace why)
 115 {
 116         unsigned int id;
 117         bool dead;
 118         int r;
 119
 120         if (bundle) {
 121                 id = bundle->debug_id;
 122                 dead = __refcount_dec_and_test(&bundle->ref, &r);
 123                 trace_rxrpc_bundle(id, r - 1, why);
 124                 if (dead)
 125                         rxrpc_free_bundle(bundle);
 126         }
 127 }
 128
 129 /*
 130  * Get rid of outstanding client connection preallocations when a local
 131  * endpoint is destroyed.
 132  */
 133 void rxrpc_purge_client_connections(struct rxrpc_local *local)
 134 {
 135         rxrpc_destroy_client_conn_ids(local);
 136 }
 137
 138 /*
 139  * Allocate a client connection.
 140  */
 141 static struct rxrpc_connection *
 142 rxrpc_alloc_client_connection(struct rxrpc_bundle *bundle)
 143 {
 144         struct rxrpc_connection *conn;
 145         struct rxrpc_local *local = bundle->local;
 146         struct rxrpc_net *rxnet = local->rxnet;
 147         int id;
 148
 149         _enter("");
 150
 151         conn = rxrpc_alloc_connection(rxnet, GFP_ATOMIC | __GFP_NOWARN);
 152         if (!conn)
 153                 return ERR_PTR(-ENOMEM);
 154
 155         id = idr_alloc_cyclic(&local->conn_ids, conn, 1, 0x40000000,
 156                               GFP_ATOMIC | __GFP_NOWARN);
 157         if (id < 0) {
 158                 kfree(conn);
 159                 return ERR_PTR(id);
 160         }
 161
 162         refcount_set(&conn->ref, 1);
 163         conn->proto.cid         = id << RXRPC_CIDSHIFT;
 164         conn->proto.epoch       = local->rxnet->epoch;
 165         conn->out_clientflag    = RXRPC_CLIENT_INITIATED;
 166         conn->bundle            = rxrpc_get_bundle(bundle, rxrpc_bundle_get_client_conn);
 167         conn->local             = rxrpc_get_local(bundle->local, rxrpc_local_get_client_conn);
 168         conn->peer              = rxrpc_get_peer(bundle->peer, rxrpc_peer_get_client_conn);
 169         conn->key               = key_get(bundle->key);
 170         conn->security          = bundle->security;
 171         conn->exclusive         = bundle->exclusive;
 172         conn->upgrade           = bundle->upgrade;
 173         conn->orig_service_id   = bundle->service_id;
 174         conn->security_level    = bundle->security_level;
 175         conn->state             = RXRPC_CONN_CLIENT_UNSECURED;
 176         conn->service_id        = conn->orig_service_id;
 177
 178         if (conn->security == &rxrpc_no_security)
 179                 conn->state     = RXRPC_CONN_CLIENT;
 180
 181         atomic_inc(&rxnet->nr_conns);
 182         write_lock(&rxnet->conn_lock);
 183         list_add_tail(&conn->proc_link, &rxnet->conn_proc_list);
 184         write_unlock(&rxnet->conn_lock);
 185
 186         rxrpc_see_connection(conn, rxrpc_conn_new_client);
 187
 188         atomic_inc(&rxnet->nr_client_conns);
 189         trace_rxrpc_client(conn, -1, rxrpc_client_alloc);
 190         return conn;
 191 }
 192
 193 /*
 194  * Determine if a connection may be reused.
 195  */
 196 static bool rxrpc_may_reuse_conn(struct rxrpc_connection *conn)
 197 {
 198         struct rxrpc_net *rxnet;
 199         int id_cursor, id, distance, limit;
 200
 201         if (!conn)
 202                 goto dont_reuse;
 203
 204         rxnet = conn->rxnet;
 205         if (test_bit(RXRPC_CONN_DONT_REUSE, &conn->flags))
 206                 goto dont_reuse;
 207
 208         if ((conn->state != RXRPC_CONN_CLIENT_UNSECURED &&
 209              conn->state != RXRPC_CONN_CLIENT) ||
 210             conn->proto.epoch != rxnet->epoch)
 211                 goto mark_dont_reuse;
 212
 213         /* The IDR tree gets very expensive on memory if the connection IDs are
 214          * widely scattered throughout the number space, so we shall want to
 215          * kill off connections that, say, have an ID more than about four
 216          * times the maximum number of client conns away from the current
 217          * allocation point to try and keep the IDs concentrated.
 218          */
 219         id_cursor = idr_get_cursor(&conn->local->conn_ids);
 220         id = conn->proto.cid >> RXRPC_CIDSHIFT;
 221         distance = id - id_cursor;
 222         if (distance < 0)
 223                 distance = -distance;
 224         limit = max_t(unsigned long, atomic_read(&rxnet->nr_conns) * 4, 1024);
 225         if (distance > limit)
 226                 goto mark_dont_reuse;
 227
 228         return true;
 229
 230 mark_dont_reuse:
 231         set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
 232 dont_reuse:
 233         return false;
 234 }
 235
 236 /*
 237  * Look up the conn bundle that matches the connection parameters, adding it if
 238  * it doesn't yet exist.
 239  */
 240 int rxrpc_look_up_bundle(struct rxrpc_call *call, gfp_t gfp)
 241 {
 242         static atomic_t rxrpc_bundle_id;
 243         struct rxrpc_bundle *bundle, *candidate;
 244         struct rxrpc_local *local = call->local;
 245         struct rb_node *p, **pp, *parent;
 246         long diff;
 247         bool upgrade = test_bit(RXRPC_CALL_UPGRADE, &call->flags);
 248
 249         _enter("{%px,%x,%u,%u}",
 250                call->peer, key_serial(call->key), call->security_level,
 251                upgrade);
 252
 253         if (test_bit(RXRPC_CALL_EXCLUSIVE, &call->flags)) {
 254                 call->bundle = rxrpc_alloc_bundle(call, gfp);
 255                 return call->bundle ? 0 : -ENOMEM;
 256         }
 257
 258         /* First, see if the bundle is already there. */
 259         _debug("search 1");
 260         spin_lock(&local->client_bundles_lock);
 261         p = local->client_bundles.rb_node;
 262         while (p) {
 263                 bundle = rb_entry(p, struct rxrpc_bundle, local_node);
 264
 265 #define cmp(X, Y) ((long)(X) - (long)(Y))
 266                 diff = (cmp(bundle->peer, call->peer) ?:
 267                         cmp(bundle->key, call->key) ?:
 268                         cmp(bundle->security_level, call->security_level) ?:
 269                         cmp(bundle->upgrade, upgrade));
 270 #undef cmp
 271                 if (diff < 0)
 272                         p = p->rb_left;
 273                 else if (diff > 0)
 274                         p = p->rb_right;
 275                 else
 276                         goto found_bundle;
 277         }
 278         spin_unlock(&local->client_bundles_lock);
 279         _debug("not found");
 280
 281         /* It wasn't.  We need to add one. */
 282         candidate = rxrpc_alloc_bundle(call, gfp);
 283         if (!candidate)
 284                 return -ENOMEM;
 285
 286         _debug("search 2");
 287         spin_lock(&local->client_bundles_lock);
 288         pp = &local->client_bundles.rb_node;
 289         parent = NULL;
 290         while (*pp) {
 291                 parent = *pp;
 292                 bundle = rb_entry(parent, struct rxrpc_bundle, local_node);
 293
 294 #define cmp(X, Y) ((long)(X) - (long)(Y))
 295                 diff = (cmp(bundle->peer, call->peer) ?:
 296                         cmp(bundle->key, call->key) ?:
 297                         cmp(bundle->security_level, call->security_level) ?:
 298                         cmp(bundle->upgrade, upgrade));
 299 #undef cmp
 300                 if (diff < 0)
 301                         pp = &(*pp)->rb_left;
 302                 else if (diff > 0)
 303                         pp = &(*pp)->rb_right;
 304                 else
 305                         goto found_bundle_free;
 306         }
 307
 308         _debug("new bundle");
 309         candidate->debug_id = atomic_inc_return(&rxrpc_bundle_id);
 310         rb_link_node(&candidate->local_node, parent, pp);
 311         rb_insert_color(&candidate->local_node, &local->client_bundles);
 312         call->bundle = rxrpc_get_bundle(candidate, rxrpc_bundle_get_client_call);
 313         spin_unlock(&local->client_bundles_lock);
 314         _leave(" = B=%u [new]", call->bundle->debug_id);
 315         return 0;
 316
 317 found_bundle_free:
 318         rxrpc_free_bundle(candidate);
 319 found_bundle:
 320         call->bundle = rxrpc_get_bundle(bundle, rxrpc_bundle_get_client_call);
 321         rxrpc_activate_bundle(bundle);
 322         spin_unlock(&local->client_bundles_lock);
 323         _leave(" = B=%u [found]", call->bundle->debug_id);
 324         return 0;
 325 }
 326
 327 /*
 328  * Allocate a new connection and add it into a bundle.
 329  */
 330 static bool rxrpc_add_conn_to_bundle(struct rxrpc_bundle *bundle,
 331                                      unsigned int slot)
 332 {
 333         struct rxrpc_connection *conn, *old;
 334         unsigned int shift = slot * RXRPC_MAXCALLS;
 335         unsigned int i;
 336
 337         old = bundle->conns[slot];
 338         if (old) {
 339                 bundle->conns[slot] = NULL;
 340                 trace_rxrpc_client(old, -1, rxrpc_client_replace);
 341                 rxrpc_put_connection(old, rxrpc_conn_put_noreuse);
 342         }
 343
 344         conn = rxrpc_alloc_client_connection(bundle);
 345         if (IS_ERR(conn)) {
 346                 bundle->alloc_error = PTR_ERR(conn);
 347                 return false;
 348         }
 349
 350         rxrpc_activate_bundle(bundle);
 351         conn->bundle_shift = shift;
 352         bundle->conns[slot] = conn;
 353         for (i = 0; i < RXRPC_MAXCALLS; i++)
 354                 set_bit(shift + i, &bundle->avail_chans);
 355         return true;
 356 }
 357
 358 /*
 359  * Add a connection to a bundle if there are no usable connections or we have
 360  * connections waiting for extra capacity.
 361  */
 362 static bool rxrpc_bundle_has_space(struct rxrpc_bundle *bundle)
 363 {
 364         int slot = -1, i, usable;
 365
 366         _enter("");
 367
 368         bundle->alloc_error = 0;
 369
 370         /* See if there are any usable connections. */
 371         usable = 0;
 372         for (i = 0; i < ARRAY_SIZE(bundle->conns); i++) {
 373                 if (rxrpc_may_reuse_conn(bundle->conns[i]))
 374                         usable++;
 375                 else if (slot == -1)
 376                         slot = i;
 377         }
 378
 379         if (!usable && bundle->upgrade)
 380                 bundle->try_upgrade = true;
 381
 382         if (!usable)
 383                 goto alloc_conn;
 384
 385         if (!bundle->avail_chans &&
 386             !bundle->try_upgrade &&
 387             usable < ARRAY_SIZE(bundle->conns))
 388                 goto alloc_conn;
 389
 390         _leave("");
 391         return usable;
 392
 393 alloc_conn:
 394         return slot >= 0 ? rxrpc_add_conn_to_bundle(bundle, slot) : false;
 395 }
 396
 397 /*
 398  * Assign a channel to the call at the front of the queue and wake the call up.
 399  * We don't increment the callNumber counter until this number has been exposed
 400  * to the world.
 401  */
 402 static void rxrpc_activate_one_channel(struct rxrpc_connection *conn,
 403                                        unsigned int channel)
 404 {
 405         struct rxrpc_channel *chan = &conn->channels[channel];
 406         struct rxrpc_bundle *bundle = conn->bundle;
 407         struct rxrpc_call *call = list_entry(bundle->waiting_calls.next,
 408                                              struct rxrpc_call, wait_link);
 409         u32 call_id = chan->call_counter + 1;
 410
 411         _enter("C=%x,%u", conn->debug_id, channel);
 412
 413         list_del_init(&call->wait_link);
 414
 415         trace_rxrpc_client(conn, channel, rxrpc_client_chan_activate);
 416
 417         /* Cancel the final ACK on the previous call if it hasn't been sent yet
 418          * as the DATA packet will implicitly ACK it.
 419          */
 420         clear_bit(RXRPC_CONN_FINAL_ACK_0 + channel, &conn->flags);
 421         clear_bit(conn->bundle_shift + channel, &bundle->avail_chans);
 422
 423         rxrpc_see_call(call, rxrpc_call_see_activate_client);
 424         call->conn      = rxrpc_get_connection(conn, rxrpc_conn_get_activate_call);
 425         call->cid       = conn->proto.cid | channel;
 426         call->call_id   = call_id;
 427         call->dest_srx.srx_service = conn->service_id;
 428         call->cong_ssthresh = call->peer->cong_ssthresh;
 429         if (call->cong_cwnd >= call->cong_ssthresh)
 430                 call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
 431         else
 432                 call->cong_mode = RXRPC_CALL_SLOW_START;
 433
 434         chan->call_id           = call_id;
 435         chan->call_debug_id     = call->debug_id;
 436         chan->call              = call;
 437
 438         rxrpc_see_call(call, rxrpc_call_see_connected);
 439         trace_rxrpc_connect_call(call);
 440         call->tx_last_sent = ktime_get_real();
 441         rxrpc_start_call_timer(call);
 442         rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_SEND_REQUEST);
 443         wake_up(&call->waitq);
 444 }
 445
 446 /*
 447  * Remove a connection from the idle list if it's on it.
 448  */
 449 static void rxrpc_unidle_conn(struct rxrpc_connection *conn)
 450 {
 451         if (!list_empty(&conn->cache_link)) {
 452                 list_del_init(&conn->cache_link);
 453                 rxrpc_put_connection(conn, rxrpc_conn_put_unidle);
 454         }
 455 }
 456
 457 /*
 458  * Assign channels and callNumbers to waiting calls.
 459  */
 460 static void rxrpc_activate_channels(struct rxrpc_bundle *bundle)
 461 {
 462         struct rxrpc_connection *conn;
 463         unsigned long avail, mask;
 464         unsigned int channel, slot;
 465
 466         trace_rxrpc_client(NULL, -1, rxrpc_client_activate_chans);
 467
 468         if (bundle->try_upgrade)
 469                 mask = 1;
 470         else
 471                 mask = ULONG_MAX;
 472
 473         while (!list_empty(&bundle->waiting_calls)) {
 474                 avail = bundle->avail_chans & mask;
 475                 if (!avail)
 476                         break;
 477                 channel = __ffs(avail);
 478                 clear_bit(channel, &bundle->avail_chans);
 479
 480                 slot = channel / RXRPC_MAXCALLS;
 481                 conn = bundle->conns[slot];
 482                 if (!conn)
 483                         break;
 484
 485                 if (bundle->try_upgrade)
 486                         set_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags);
 487                 rxrpc_unidle_conn(conn);
 488
 489                 channel &= (RXRPC_MAXCALLS - 1);
 490                 conn->act_chans |= 1 << channel;
 491                 rxrpc_activate_one_channel(conn, channel);
 492         }
 493 }
 494
 495 /*
 496  * Connect waiting channels (called from the I/O thread).
 497  */
 498 void rxrpc_connect_client_calls(struct rxrpc_local *local)
 499 {
 500         struct rxrpc_call *call;
 501
 502         while ((call = list_first_entry_or_null(&local->new_client_calls,
 503                                                 struct rxrpc_call, wait_link))
 504                ) {
 505                 struct rxrpc_bundle *bundle = call->bundle;
 506
 507                 spin_lock(&local->client_call_lock);
 508                 list_move_tail(&call->wait_link, &bundle->waiting_calls);
 509                 spin_unlock(&local->client_call_lock);
 510
 511                 if (rxrpc_bundle_has_space(bundle))
 512                         rxrpc_activate_channels(bundle);
 513         }
 514 }
 515
 516 /*
 517  * Note that a call, and thus a connection, is about to be exposed to the
 518  * world.
 519  */
 520 void rxrpc_expose_client_call(struct rxrpc_call *call)
 521 {
 522         unsigned int channel = call->cid & RXRPC_CHANNELMASK;
 523         struct rxrpc_connection *conn = call->conn;
 524         struct rxrpc_channel *chan = &conn->channels[channel];
 525
 526         if (!test_and_set_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 527                 /* Mark the call ID as being used.  If the callNumber counter
 528                  * exceeds ~2 billion, we kill the connection after its
 529                  * outstanding calls have finished so that the counter doesn't
 530                  * wrap.
 531                  */
 532                 chan->call_counter++;
 533                 if (chan->call_counter >= INT_MAX)
 534                         set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
 535                 trace_rxrpc_client(conn, channel, rxrpc_client_exposed);
 536
 537                 spin_lock(&call->peer->lock);
 538                 hlist_add_head(&call->error_link, &call->peer->error_targets);
 539                 spin_unlock(&call->peer->lock);
 540         }
 541 }
 542
 543 /*
 544  * Set the reap timer.
 545  */
 546 static void rxrpc_set_client_reap_timer(struct rxrpc_local *local)
 547 {
 548         if (!local->kill_all_client_conns) {
 549                 unsigned long now = jiffies;
 550                 unsigned long reap_at = now + rxrpc_conn_idle_client_expiry;
 551
 552                 if (local->rxnet->live)
 553                         timer_reduce(&local->client_conn_reap_timer, reap_at);
 554         }
 555 }
 556
 557 /*
 558  * Disconnect a client call.
 559  */
 560 void rxrpc_disconnect_client_call(struct rxrpc_bundle *bundle, struct rxrpc_call *call)
 561 {
 562         struct rxrpc_connection *conn;
 563         struct rxrpc_channel *chan = NULL;
 564         struct rxrpc_local *local = bundle->local;
 565         unsigned int channel;
 566         bool may_reuse;
 567         u32 cid;
 568
 569         _enter("c=%x", call->debug_id);
 570
 571         /* Calls that have never actually been assigned a channel can simply be
 572          * discarded.
 573          */
 574         conn = call->conn;
 575         if (!conn) {
 576                 _debug("call is waiting");
 577                 ASSERTCMP(call->call_id, ==, 0);
 578                 ASSERT(!test_bit(RXRPC_CALL_EXPOSED, &call->flags));
 579                 list_del_init(&call->wait_link);
 580                 return;
 581         }
 582
 583         cid = call->cid;
 584         channel = cid & RXRPC_CHANNELMASK;
 585         chan = &conn->channels[channel];
 586         trace_rxrpc_client(conn, channel, rxrpc_client_chan_disconnect);
 587
 588         if (WARN_ON(chan->call != call))
 589                 return;
 590
 591         may_reuse = rxrpc_may_reuse_conn(conn);
 592
 593         /* If a client call was exposed to the world, we save the result for
 594          * retransmission.
 595          *
 596          * We use a barrier here so that the call number and abort code can be
 597          * read without needing to take a lock.
 598          *
 599          * TODO: Make the incoming packet handler check this and handle
 600          * terminal retransmission without requiring access to the call.
 601          */
 602         if (test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 603                 _debug("exposed %u,%u", call->call_id, call->abort_code);
 604                 __rxrpc_disconnect_call(conn, call);
 605
 606                 if (test_and_clear_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags)) {
 607                         trace_rxrpc_client(conn, channel, rxrpc_client_to_active);
 608                         bundle->try_upgrade = false;
 609                         if (may_reuse)
 610                                 rxrpc_activate_channels(bundle);
 611                 }
 612         }
 613
 614         /* See if we can pass the channel directly to another call. */
 615         if (may_reuse && !list_empty(&bundle->waiting_calls)) {
 616                 trace_rxrpc_client(conn, channel, rxrpc_client_chan_pass);
 617                 rxrpc_activate_one_channel(conn, channel);
 618                 return;
 619         }
 620
 621         /* Schedule the final ACK to be transmitted in a short while so that it
 622          * can be skipped if we find a follow-on call.  The first DATA packet
 623          * of the follow on call will implicitly ACK this call.
 624          */
 625         if (call->completion == RXRPC_CALL_SUCCEEDED &&
 626             test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 627                 unsigned long final_ack_at = jiffies + 2;
 628
 629                 WRITE_ONCE(chan->final_ack_at, final_ack_at);
 630                 smp_wmb(); /* vs rxrpc_process_delayed_final_acks() */
 631                 set_bit(RXRPC_CONN_FINAL_ACK_0 + channel, &conn->flags);
 632                 rxrpc_reduce_conn_timer(conn, final_ack_at);
 633         }
 634
 635         /* Deactivate the channel. */
 636         chan->call = NULL;
 637         set_bit(conn->bundle_shift + channel, &conn->bundle->avail_chans);
 638         conn->act_chans &= ~(1 << channel);
 639
 640         /* If no channels remain active, then put the connection on the idle
 641          * list for a short while.  Give it a ref to stop it going away if it
 642          * becomes unbundled.
 643          */
 644         if (!conn->act_chans) {
 645                 trace_rxrpc_client(conn, channel, rxrpc_client_to_idle);
 646                 conn->idle_timestamp = jiffies;
 647
 648                 rxrpc_get_connection(conn, rxrpc_conn_get_idle);
 649                 list_move_tail(&conn->cache_link, &local->idle_client_conns);
 650
 651                 rxrpc_set_client_reap_timer(local);
 652         }
 653 }
 654
 655 /*
 656  * Remove a connection from a bundle.
 657  */
 658 static void rxrpc_unbundle_conn(struct rxrpc_connection *conn)
 659 {
 660         struct rxrpc_bundle *bundle = conn->bundle;
 661         unsigned int bindex;
 662         int i;
 663
 664         _enter("C=%x", conn->debug_id);
 665
 666         if (conn->flags & RXRPC_CONN_FINAL_ACK_MASK)
 667                 rxrpc_process_delayed_final_acks(conn, true);
 668
 669         bindex = conn->bundle_shift / RXRPC_MAXCALLS;
 670         if (bundle->conns[bindex] == conn) {
 671                 _debug("clear slot %u", bindex);
 672                 bundle->conns[bindex] = NULL;
 673                 for (i = 0; i < RXRPC_MAXCALLS; i++)
 674                         clear_bit(conn->bundle_shift + i, &bundle->avail_chans);
 675                 rxrpc_put_client_connection_id(bundle->local, conn);
 676                 rxrpc_deactivate_bundle(bundle);
 677                 rxrpc_put_connection(conn, rxrpc_conn_put_unbundle);
 678         }
 679 }
 680
 681 /*
 682  * Drop the active count on a bundle.
 683  */
 684 void rxrpc_deactivate_bundle(struct rxrpc_bundle *bundle)
 685 {
 686         struct rxrpc_local *local;
 687         bool need_put = false;
 688
 689         if (!bundle)
 690                 return;
 691
 692         local = bundle->local;
 693         if (atomic_dec_and_lock(&bundle->active, &local->client_bundles_lock)) {
 694                 if (!bundle->exclusive) {
 695                         _debug("erase bundle");
 696                         rb_erase(&bundle->local_node, &local->client_bundles);
 697                         need_put = true;
 698                 }
 699
 700                 spin_unlock(&local->client_bundles_lock);
 701                 if (need_put)
 702                         rxrpc_put_bundle(bundle, rxrpc_bundle_put_discard);
 703         }
 704 }
 705
 706 /*
 707  * Clean up a dead client connection.
 708  */
 709 void rxrpc_kill_client_conn(struct rxrpc_connection *conn)
 710 {
 711         struct rxrpc_local *local = conn->local;
 712         struct rxrpc_net *rxnet = local->rxnet;
 713
 714         _enter("C=%x", conn->debug_id);
 715
 716         trace_rxrpc_client(conn, -1, rxrpc_client_cleanup);
 717         atomic_dec(&rxnet->nr_client_conns);
 718
 719         rxrpc_put_client_connection_id(local, conn);
 720 }
 721
 722 /*
 723  * Discard expired client connections from the idle list.  Each conn in the
 724  * idle list has been exposed and holds an extra ref because of that.
 725  *
 726  * This may be called from conn setup or from a work item so cannot be
 727  * considered non-reentrant.
 728  */
 729 void rxrpc_discard_expired_client_conns(struct rxrpc_local *local)
 730 {
 731         struct rxrpc_connection *conn;
 732         unsigned long expiry, conn_expires_at, now;
 733         unsigned int nr_conns;
 734
 735         _enter("");
 736
 737         /* We keep an estimate of what the number of conns ought to be after
 738          * we've discarded some so that we don't overdo the discarding.
 739          */
 740         nr_conns = atomic_read(&local->rxnet->nr_client_conns);
 741
 742 next:
 743         conn = list_first_entry_or_null(&local->idle_client_conns,
 744                                         struct rxrpc_connection, cache_link);
 745         if (!conn)
 746                 return;
 747
 748         if (!local->kill_all_client_conns) {
 749                 /* If the number of connections is over the reap limit, we
 750                  * expedite discard by reducing the expiry timeout.  We must,
 751                  * however, have at least a short grace period to be able to do
 752                  * final-ACK or ABORT retransmission.
 753                  */
 754                 expiry = rxrpc_conn_idle_client_expiry;
 755                 if (nr_conns > rxrpc_reap_client_connections)
 756                         expiry = rxrpc_conn_idle_client_fast_expiry;
 757                 if (conn->local->service_closed)
 758                         expiry = rxrpc_closed_conn_expiry * HZ;
 759
 760                 conn_expires_at = conn->idle_timestamp + expiry;
 761
 762                 now = READ_ONCE(jiffies);
 763                 if (time_after(conn_expires_at, now))
 764                         goto not_yet_expired;
 765         }
 766
 767         atomic_dec(&conn->active);
 768         trace_rxrpc_client(conn, -1, rxrpc_client_discard);
 769         list_del_init(&conn->cache_link);
 770
 771         rxrpc_unbundle_conn(conn);
 772         /* Drop the ->cache_link ref */
 773         rxrpc_put_connection(conn, rxrpc_conn_put_discard_idle);
 774
 775         nr_conns--;
 776         goto next;
 777
 778 not_yet_expired:
 779         /* The connection at the front of the queue hasn't yet expired, so
 780          * schedule the work item for that point if we discarded something.
 781          *
 782          * We don't worry if the work item is already scheduled - it can look
 783          * after rescheduling itself at a later time.  We could cancel it, but
 784          * then things get messier.
 785          */
 786         _debug("not yet");
 787         if (!local->kill_all_client_conns)
 788                 timer_reduce(&local->client_conn_reap_timer, conn_expires_at);
 789
 790         _leave("");
 791 }
 792
 793 /*
 794  * Clean up the client connections on a local endpoint.
 795  */
 796 void rxrpc_clean_up_local_conns(struct rxrpc_local *local)
 797 {
 798         struct rxrpc_connection *conn;
 799
 800         _enter("");
 801
 802         local->kill_all_client_conns = true;
 803
 804         del_timer_sync(&local->client_conn_reap_timer);
 805
 806         while ((conn = list_first_entry_or_null(&local->idle_client_conns,
 807                                                 struct rxrpc_connection, cache_link))) {
 808                 list_del_init(&conn->cache_link);
 809                 atomic_dec(&conn->active);
 810                 trace_rxrpc_client(conn, -1, rxrpc_client_discard);
 811                 rxrpc_unbundle_conn(conn);
 812                 rxrpc_put_connection(conn, rxrpc_conn_put_local_dead);
 813         }
 814
 815         _leave(" [culled]");
 816 }