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         static atomic_t rxrpc_bundle_id;
  77         struct rxrpc_bundle *bundle;
  78
  79         bundle = kzalloc(sizeof(*bundle), gfp);
  80         if (bundle) {
  81                 bundle->local           = call->local;
  82                 bundle->peer            = rxrpc_get_peer(call->peer, rxrpc_peer_get_bundle);
  83                 bundle->key             = key_get(call->key);
  84                 bundle->security        = call->security;
  85                 bundle->exclusive       = test_bit(RXRPC_CALL_EXCLUSIVE, &call->flags);
  86                 bundle->upgrade         = test_bit(RXRPC_CALL_UPGRADE, &call->flags);
  87                 bundle->service_id      = call->dest_srx.srx_service;
  88                 bundle->security_level  = call->security_level;
  89                 bundle->debug_id        = atomic_inc_return(&rxrpc_bundle_id);
  90                 refcount_set(&bundle->ref, 1);
  91                 atomic_set(&bundle->active, 1);
  92                 INIT_LIST_HEAD(&bundle->waiting_calls);
  93                 trace_rxrpc_bundle(bundle->debug_id, 1, rxrpc_bundle_new);
  94         }
  95         return bundle;
  96 }
  97
  98 struct rxrpc_bundle *rxrpc_get_bundle(struct rxrpc_bundle *bundle,
  99                                       enum rxrpc_bundle_trace why)
 100 {
 101         int r;
 102
 103         __refcount_inc(&bundle->ref, &r);
 104         trace_rxrpc_bundle(bundle->debug_id, r + 1, why);
 105         return bundle;
 106 }
 107
 108 static void rxrpc_free_bundle(struct rxrpc_bundle *bundle)
 109 {
 110         trace_rxrpc_bundle(bundle->debug_id, refcount_read(&bundle->ref),
 111                            rxrpc_bundle_free);
 112         rxrpc_put_peer(bundle->peer, rxrpc_peer_put_bundle);
 113         key_put(bundle->key);
 114         kfree(bundle);
 115 }
 116
 117 void rxrpc_put_bundle(struct rxrpc_bundle *bundle, enum rxrpc_bundle_trace why)
 118 {
 119         unsigned int id;
 120         bool dead;
 121         int r;
 122
 123         if (bundle) {
 124                 id = bundle->debug_id;
 125                 dead = __refcount_dec_and_test(&bundle->ref, &r);
 126                 trace_rxrpc_bundle(id, r - 1, why);
 127                 if (dead)
 128                         rxrpc_free_bundle(bundle);
 129         }
 130 }
 131
 132 /*
 133  * Get rid of outstanding client connection preallocations when a local
 134  * endpoint is destroyed.
 135  */
 136 void rxrpc_purge_client_connections(struct rxrpc_local *local)
 137 {
 138         rxrpc_destroy_client_conn_ids(local);
 139 }
 140
 141 /*
 142  * Allocate a client connection.
 143  */
 144 static struct rxrpc_connection *
 145 rxrpc_alloc_client_connection(struct rxrpc_bundle *bundle)
 146 {
 147         struct rxrpc_connection *conn;
 148         struct rxrpc_local *local = bundle->local;
 149         struct rxrpc_net *rxnet = local->rxnet;
 150         int id;
 151
 152         _enter("");
 153
 154         conn = rxrpc_alloc_connection(rxnet, GFP_ATOMIC | __GFP_NOWARN);
 155         if (!conn)
 156                 return ERR_PTR(-ENOMEM);
 157
 158         id = idr_alloc_cyclic(&local->conn_ids, conn, 1, 0x40000000,
 159                               GFP_ATOMIC | __GFP_NOWARN);
 160         if (id < 0) {
 161                 kfree(conn);
 162                 return ERR_PTR(id);
 163         }
 164
 165         refcount_set(&conn->ref, 1);
 166         conn->proto.cid         = id << RXRPC_CIDSHIFT;
 167         conn->proto.epoch       = local->rxnet->epoch;
 168         conn->out_clientflag    = RXRPC_CLIENT_INITIATED;
 169         conn->bundle            = rxrpc_get_bundle(bundle, rxrpc_bundle_get_client_conn);
 170         conn->local             = rxrpc_get_local(bundle->local, rxrpc_local_get_client_conn);
 171         conn->peer              = rxrpc_get_peer(bundle->peer, rxrpc_peer_get_client_conn);
 172         conn->key               = key_get(bundle->key);
 173         conn->security          = bundle->security;
 174         conn->exclusive         = bundle->exclusive;
 175         conn->upgrade           = bundle->upgrade;
 176         conn->orig_service_id   = bundle->service_id;
 177         conn->security_level    = bundle->security_level;
 178         conn->state             = RXRPC_CONN_CLIENT_UNSECURED;
 179         conn->service_id        = conn->orig_service_id;
 180
 181         if (conn->security == &rxrpc_no_security)
 182                 conn->state     = RXRPC_CONN_CLIENT;
 183
 184         atomic_inc(&rxnet->nr_conns);
 185         write_lock(&rxnet->conn_lock);
 186         list_add_tail(&conn->proc_link, &rxnet->conn_proc_list);
 187         write_unlock(&rxnet->conn_lock);
 188
 189         rxrpc_see_connection(conn, rxrpc_conn_new_client);
 190
 191         atomic_inc(&rxnet->nr_client_conns);
 192         trace_rxrpc_client(conn, -1, rxrpc_client_alloc);
 193         return conn;
 194 }
 195
 196 /*
 197  * Determine if a connection may be reused.
 198  */
 199 static bool rxrpc_may_reuse_conn(struct rxrpc_connection *conn)
 200 {
 201         struct rxrpc_net *rxnet;
 202         int id_cursor, id, distance, limit;
 203
 204         if (!conn)
 205                 goto dont_reuse;
 206
 207         rxnet = conn->rxnet;
 208         if (test_bit(RXRPC_CONN_DONT_REUSE, &conn->flags))
 209                 goto dont_reuse;
 210
 211         if ((conn->state != RXRPC_CONN_CLIENT_UNSECURED &&
 212              conn->state != RXRPC_CONN_CLIENT) ||
 213             conn->proto.epoch != rxnet->epoch)
 214                 goto mark_dont_reuse;
 215
 216         /* The IDR tree gets very expensive on memory if the connection IDs are
 217          * widely scattered throughout the number space, so we shall want to
 218          * kill off connections that, say, have an ID more than about four
 219          * times the maximum number of client conns away from the current
 220          * allocation point to try and keep the IDs concentrated.
 221          */
 222         id_cursor = idr_get_cursor(&conn->local->conn_ids);
 223         id = conn->proto.cid >> RXRPC_CIDSHIFT;
 224         distance = id - id_cursor;
 225         if (distance < 0)
 226                 distance = -distance;
 227         limit = max_t(unsigned long, atomic_read(&rxnet->nr_conns) * 4, 1024);
 228         if (distance > limit)
 229                 goto mark_dont_reuse;
 230
 231         return true;
 232
 233 mark_dont_reuse:
 234         set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
 235 dont_reuse:
 236         return false;
 237 }
 238
 239 /*
 240  * Look up the conn bundle that matches the connection parameters, adding it if
 241  * it doesn't yet exist.
 242  */
 243 int rxrpc_look_up_bundle(struct rxrpc_call *call, gfp_t gfp)
 244 {
 245         struct rxrpc_bundle *bundle, *candidate;
 246         struct rxrpc_local *local = call->local;
 247         struct rb_node *p, **pp, *parent;
 248         long diff;
 249         bool upgrade = test_bit(RXRPC_CALL_UPGRADE, &call->flags);
 250
 251         _enter("{%px,%x,%u,%u}",
 252                call->peer, key_serial(call->key), call->security_level,
 253                upgrade);
 254
 255         if (test_bit(RXRPC_CALL_EXCLUSIVE, &call->flags)) {
 256                 call->bundle = rxrpc_alloc_bundle(call, gfp);
 257                 return call->bundle ? 0 : -ENOMEM;
 258         }
 259
 260         /* First, see if the bundle is already there. */
 261         _debug("search 1");
 262         spin_lock(&local->client_bundles_lock);
 263         p = local->client_bundles.rb_node;
 264         while (p) {
 265                 bundle = rb_entry(p, struct rxrpc_bundle, local_node);
 266
 267 #define cmp(X, Y) ((long)(X) - (long)(Y))
 268                 diff = (cmp(bundle->peer, call->peer) ?:
 269                         cmp(bundle->key, call->key) ?:
 270                         cmp(bundle->security_level, call->security_level) ?:
 271                         cmp(bundle->upgrade, upgrade));
 272 #undef cmp
 273                 if (diff < 0)
 274                         p = p->rb_left;
 275                 else if (diff > 0)
 276                         p = p->rb_right;
 277                 else
 278                         goto found_bundle;
 279         }
 280         spin_unlock(&local->client_bundles_lock);
 281         _debug("not found");
 282
 283         /* It wasn't.  We need to add one. */
 284         candidate = rxrpc_alloc_bundle(call, gfp);
 285         if (!candidate)
 286                 return -ENOMEM;
 287
 288         _debug("search 2");
 289         spin_lock(&local->client_bundles_lock);
 290         pp = &local->client_bundles.rb_node;
 291         parent = NULL;
 292         while (*pp) {
 293                 parent = *pp;
 294                 bundle = rb_entry(parent, struct rxrpc_bundle, local_node);
 295
 296 #define cmp(X, Y) ((long)(X) - (long)(Y))
 297                 diff = (cmp(bundle->peer, call->peer) ?:
 298                         cmp(bundle->key, call->key) ?:
 299                         cmp(bundle->security_level, call->security_level) ?:
 300                         cmp(bundle->upgrade, upgrade));
 301 #undef cmp
 302                 if (diff < 0)
 303                         pp = &(*pp)->rb_left;
 304                 else if (diff > 0)
 305                         pp = &(*pp)->rb_right;
 306                 else
 307                         goto found_bundle_free;
 308         }
 309
 310         _debug("new bundle");
 311         rb_link_node(&candidate->local_node, parent, pp);
 312         rb_insert_color(&candidate->local_node, &local->client_bundles);
 313         call->bundle = rxrpc_get_bundle(candidate, rxrpc_bundle_get_client_call);
 314         spin_unlock(&local->client_bundles_lock);
 315         _leave(" = B=%u [new]", call->bundle->debug_id);
 316         return 0;
 317
 318 found_bundle_free:
 319         rxrpc_free_bundle(candidate);
 320 found_bundle:
 321         call->bundle = rxrpc_get_bundle(bundle, rxrpc_bundle_get_client_call);
 322         rxrpc_activate_bundle(bundle);
 323         spin_unlock(&local->client_bundles_lock);
 324         _leave(" = B=%u [found]", call->bundle->debug_id);
 325         return 0;
 326 }
 327
 328 /*
 329  * Allocate a new connection and add it into a bundle.
 330  */
 331 static bool rxrpc_add_conn_to_bundle(struct rxrpc_bundle *bundle,
 332                                      unsigned int slot)
 333 {
 334         struct rxrpc_connection *conn, *old;
 335         unsigned int shift = slot * RXRPC_MAXCALLS;
 336         unsigned int i;
 337
 338         old = bundle->conns[slot];
 339         if (old) {
 340                 bundle->conns[slot] = NULL;
 341                 trace_rxrpc_client(old, -1, rxrpc_client_replace);
 342                 rxrpc_put_connection(old, rxrpc_conn_put_noreuse);
 343         }
 344
 345         conn = rxrpc_alloc_client_connection(bundle);
 346         if (IS_ERR(conn)) {
 347                 bundle->alloc_error = PTR_ERR(conn);
 348                 return false;
 349         }
 350
 351         rxrpc_activate_bundle(bundle);
 352         conn->bundle_shift = shift;
 353         bundle->conns[slot] = conn;
 354         for (i = 0; i < RXRPC_MAXCALLS; i++)
 355                 set_bit(shift + i, &bundle->avail_chans);
 356         return true;
 357 }
 358
 359 /*
 360  * Add a connection to a bundle if there are no usable connections or we have
 361  * connections waiting for extra capacity.
 362  */
 363 static bool rxrpc_bundle_has_space(struct rxrpc_bundle *bundle)
 364 {
 365         int slot = -1, i, usable;
 366
 367         _enter("");
 368
 369         bundle->alloc_error = 0;
 370
 371         /* See if there are any usable connections. */
 372         usable = 0;
 373         for (i = 0; i < ARRAY_SIZE(bundle->conns); i++) {
 374                 if (rxrpc_may_reuse_conn(bundle->conns[i]))
 375                         usable++;
 376                 else if (slot == -1)
 377                         slot = i;
 378         }
 379
 380         if (!usable && bundle->upgrade)
 381                 bundle->try_upgrade = true;
 382
 383         if (!usable)
 384                 goto alloc_conn;
 385
 386         if (!bundle->avail_chans &&
 387             !bundle->try_upgrade &&
 388             usable < ARRAY_SIZE(bundle->conns))
 389                 goto alloc_conn;
 390
 391         _leave("");
 392         return usable;
 393
 394 alloc_conn:
 395         return slot >= 0 ? rxrpc_add_conn_to_bundle(bundle, slot) : false;
 396 }
 397
 398 /*
 399  * Assign a channel to the call at the front of the queue and wake the call up.
 400  * We don't increment the callNumber counter until this number has been exposed
 401  * to the world.
 402  */
 403 static void rxrpc_activate_one_channel(struct rxrpc_connection *conn,
 404                                        unsigned int channel)
 405 {
 406         struct rxrpc_channel *chan = &conn->channels[channel];
 407         struct rxrpc_bundle *bundle = conn->bundle;
 408         struct rxrpc_call *call = list_entry(bundle->waiting_calls.next,
 409                                              struct rxrpc_call, wait_link);
 410         u32 call_id = chan->call_counter + 1;
 411
 412         _enter("C=%x,%u", conn->debug_id, channel);
 413
 414         list_del_init(&call->wait_link);
 415
 416         trace_rxrpc_client(conn, channel, rxrpc_client_chan_activate);
 417
 418         /* Cancel the final ACK on the previous call if it hasn't been sent yet
 419          * as the DATA packet will implicitly ACK it.
 420          */
 421         clear_bit(RXRPC_CONN_FINAL_ACK_0 + channel, &conn->flags);
 422         clear_bit(conn->bundle_shift + channel, &bundle->avail_chans);
 423
 424         rxrpc_see_call(call, rxrpc_call_see_activate_client);
 425         call->conn      = rxrpc_get_connection(conn, rxrpc_conn_get_activate_call);
 426         call->cid       = conn->proto.cid | channel;
 427         call->call_id   = call_id;
 428         call->dest_srx.srx_service = conn->service_id;
 429         call->cong_ssthresh = call->peer->cong_ssthresh;
 430         if (call->cong_cwnd >= call->cong_ssthresh)
 431                 call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
 432         else
 433                 call->cong_mode = RXRPC_CALL_SLOW_START;
 434
 435         chan->call_id           = call_id;
 436         chan->call_debug_id     = call->debug_id;
 437         chan->call              = call;
 438
 439         rxrpc_see_call(call, rxrpc_call_see_connected);
 440         trace_rxrpc_connect_call(call);
 441         call->tx_last_sent = ktime_get_real();
 442         rxrpc_start_call_timer(call);
 443         rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_SEND_REQUEST);
 444         wake_up(&call->waitq);
 445 }
 446
 447 /*
 448  * Remove a connection from the idle list if it's on it.
 449  */
 450 static void rxrpc_unidle_conn(struct rxrpc_connection *conn)
 451 {
 452         if (!list_empty(&conn->cache_link)) {
 453                 list_del_init(&conn->cache_link);
 454                 rxrpc_put_connection(conn, rxrpc_conn_put_unidle);
 455         }
 456 }
 457
 458 /*
 459  * Assign channels and callNumbers to waiting calls.
 460  */
 461 static void rxrpc_activate_channels(struct rxrpc_bundle *bundle)
 462 {
 463         struct rxrpc_connection *conn;
 464         unsigned long avail, mask;
 465         unsigned int channel, slot;
 466
 467         trace_rxrpc_client(NULL, -1, rxrpc_client_activate_chans);
 468
 469         if (bundle->try_upgrade)
 470                 mask = 1;
 471         else
 472                 mask = ULONG_MAX;
 473
 474         while (!list_empty(&bundle->waiting_calls)) {
 475                 avail = bundle->avail_chans & mask;
 476                 if (!avail)
 477                         break;
 478                 channel = __ffs(avail);
 479                 clear_bit(channel, &bundle->avail_chans);
 480
 481                 slot = channel / RXRPC_MAXCALLS;
 482                 conn = bundle->conns[slot];
 483                 if (!conn)
 484                         break;
 485
 486                 if (bundle->try_upgrade)
 487                         set_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags);
 488                 rxrpc_unidle_conn(conn);
 489
 490                 channel &= (RXRPC_MAXCALLS - 1);
 491                 conn->act_chans |= 1 << channel;
 492                 rxrpc_activate_one_channel(conn, channel);
 493         }
 494 }
 495
 496 /*
 497  * Connect waiting channels (called from the I/O thread).
 498  */
 499 void rxrpc_connect_client_calls(struct rxrpc_local *local)
 500 {
 501         struct rxrpc_call *call;
 502
 503         while ((call = list_first_entry_or_null(&local->new_client_calls,
 504                                                 struct rxrpc_call, wait_link))
 505                ) {
 506                 struct rxrpc_bundle *bundle = call->bundle;
 507
 508                 spin_lock(&local->client_call_lock);
 509                 list_move_tail(&call->wait_link, &bundle->waiting_calls);
 510                 spin_unlock(&local->client_call_lock);
 511
 512                 if (rxrpc_bundle_has_space(bundle))
 513                         rxrpc_activate_channels(bundle);
 514         }
 515 }
 516
 517 /*
 518  * Note that a call, and thus a connection, is about to be exposed to the
 519  * world.
 520  */
 521 void rxrpc_expose_client_call(struct rxrpc_call *call)
 522 {
 523         unsigned int channel = call->cid & RXRPC_CHANNELMASK;
 524         struct rxrpc_connection *conn = call->conn;
 525         struct rxrpc_channel *chan = &conn->channels[channel];
 526
 527         if (!test_and_set_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 528                 /* Mark the call ID as being used.  If the callNumber counter
 529                  * exceeds ~2 billion, we kill the connection after its
 530                  * outstanding calls have finished so that the counter doesn't
 531                  * wrap.
 532                  */
 533                 chan->call_counter++;
 534                 if (chan->call_counter >= INT_MAX)
 535                         set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
 536                 trace_rxrpc_client(conn, channel, rxrpc_client_exposed);
 537
 538                 spin_lock(&call->peer->lock);
 539                 hlist_add_head(&call->error_link, &call->peer->error_targets);
 540                 spin_unlock(&call->peer->lock);
 541         }
 542 }
 543
 544 /*
 545  * Set the reap timer.
 546  */
 547 static void rxrpc_set_client_reap_timer(struct rxrpc_local *local)
 548 {
 549         if (!local->kill_all_client_conns) {
 550                 unsigned long now = jiffies;
 551                 unsigned long reap_at = now + rxrpc_conn_idle_client_expiry;
 552
 553                 if (local->rxnet->live)
 554                         timer_reduce(&local->client_conn_reap_timer, reap_at);
 555         }
 556 }
 557
 558 /*
 559  * Disconnect a client call.
 560  */
 561 void rxrpc_disconnect_client_call(struct rxrpc_bundle *bundle, struct rxrpc_call *call)
 562 {
 563         struct rxrpc_connection *conn;
 564         struct rxrpc_channel *chan = NULL;
 565         struct rxrpc_local *local = bundle->local;
 566         unsigned int channel;
 567         bool may_reuse;
 568         u32 cid;
 569
 570         _enter("c=%x", call->debug_id);
 571
 572         /* Calls that have never actually been assigned a channel can simply be
 573          * discarded.
 574          */
 575         conn = call->conn;
 576         if (!conn) {
 577                 _debug("call is waiting");
 578                 ASSERTCMP(call->call_id, ==, 0);
 579                 ASSERT(!test_bit(RXRPC_CALL_EXPOSED, &call->flags));
 580                 list_del_init(&call->wait_link);
 581                 return;
 582         }
 583
 584         cid = call->cid;
 585         channel = cid & RXRPC_CHANNELMASK;
 586         chan = &conn->channels[channel];
 587         trace_rxrpc_client(conn, channel, rxrpc_client_chan_disconnect);
 588
 589         if (WARN_ON(chan->call != call))
 590                 return;
 591
 592         may_reuse = rxrpc_may_reuse_conn(conn);
 593
 594         /* If a client call was exposed to the world, we save the result for
 595          * retransmission.
 596          *
 597          * We use a barrier here so that the call number and abort code can be
 598          * read without needing to take a lock.
 599          *
 600          * TODO: Make the incoming packet handler check this and handle
 601          * terminal retransmission without requiring access to the call.
 602          */
 603         if (test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 604                 _debug("exposed %u,%u", call->call_id, call->abort_code);
 605                 __rxrpc_disconnect_call(conn, call);
 606
 607                 if (test_and_clear_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags)) {
 608                         trace_rxrpc_client(conn, channel, rxrpc_client_to_active);
 609                         bundle->try_upgrade = false;
 610                         if (may_reuse)
 611                                 rxrpc_activate_channels(bundle);
 612                 }
 613         }
 614
 615         /* See if we can pass the channel directly to another call. */
 616         if (may_reuse && !list_empty(&bundle->waiting_calls)) {
 617                 trace_rxrpc_client(conn, channel, rxrpc_client_chan_pass);
 618                 rxrpc_activate_one_channel(conn, channel);
 619                 return;
 620         }
 621
 622         /* Schedule the final ACK to be transmitted in a short while so that it
 623          * can be skipped if we find a follow-on call.  The first DATA packet
 624          * of the follow on call will implicitly ACK this call.
 625          */
 626         if (call->completion == RXRPC_CALL_SUCCEEDED &&
 627             test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
 628                 unsigned long final_ack_at = jiffies + 2;
 629
 630                 WRITE_ONCE(chan->final_ack_at, final_ack_at);
 631                 smp_wmb(); /* vs rxrpc_process_delayed_final_acks() */
 632                 set_bit(RXRPC_CONN_FINAL_ACK_0 + channel, &conn->flags);
 633                 rxrpc_reduce_conn_timer(conn, final_ack_at);
 634         }
 635
 636         /* Deactivate the channel. */
 637         chan->call = NULL;
 638         set_bit(conn->bundle_shift + channel, &conn->bundle->avail_chans);
 639         conn->act_chans &= ~(1 << channel);
 640
 641         /* If no channels remain active, then put the connection on the idle
 642          * list for a short while.  Give it a ref to stop it going away if it
 643          * becomes unbundled.
 644          */
 645         if (!conn->act_chans) {
 646                 trace_rxrpc_client(conn, channel, rxrpc_client_to_idle);
 647                 conn->idle_timestamp = jiffies;
 648
 649                 rxrpc_get_connection(conn, rxrpc_conn_get_idle);
 650                 list_move_tail(&conn->cache_link, &local->idle_client_conns);
 651
 652                 rxrpc_set_client_reap_timer(local);
 653         }
 654 }
 655
 656 /*
 657  * Remove a connection from a bundle.
 658  */
 659 static void rxrpc_unbundle_conn(struct rxrpc_connection *conn)
 660 {
 661         struct rxrpc_bundle *bundle = conn->bundle;
 662         unsigned int bindex;
 663         int i;
 664
 665         _enter("C=%x", conn->debug_id);
 666
 667         if (conn->flags & RXRPC_CONN_FINAL_ACK_MASK)
 668                 rxrpc_process_delayed_final_acks(conn, true);
 669
 670         bindex = conn->bundle_shift / RXRPC_MAXCALLS;
 671         if (bundle->conns[bindex] == conn) {
 672                 _debug("clear slot %u", bindex);
 673                 bundle->conns[bindex] = NULL;
 674                 for (i = 0; i < RXRPC_MAXCALLS; i++)
 675                         clear_bit(conn->bundle_shift + i, &bundle->avail_chans);
 676                 rxrpc_put_client_connection_id(bundle->local, conn);
 677                 rxrpc_deactivate_bundle(bundle);
 678                 rxrpc_put_connection(conn, rxrpc_conn_put_unbundle);
 679         }
 680 }
 681
 682 /*
 683  * Drop the active count on a bundle.
 684  */
 685 void rxrpc_deactivate_bundle(struct rxrpc_bundle *bundle)
 686 {
 687         struct rxrpc_local *local;
 688         bool need_put = false;
 689
 690         if (!bundle)
 691                 return;
 692
 693         local = bundle->local;
 694         if (atomic_dec_and_lock(&bundle->active, &local->client_bundles_lock)) {
 695                 if (!bundle->exclusive) {
 696                         _debug("erase bundle");
 697                         rb_erase(&bundle->local_node, &local->client_bundles);
 698                         need_put = true;
 699                 }
 700
 701                 spin_unlock(&local->client_bundles_lock);
 702                 if (need_put)
 703                         rxrpc_put_bundle(bundle, rxrpc_bundle_put_discard);
 704         }
 705 }
 706
 707 /*
 708  * Clean up a dead client connection.
 709  */
 710 void rxrpc_kill_client_conn(struct rxrpc_connection *conn)
 711 {
 712         struct rxrpc_local *local = conn->local;
 713         struct rxrpc_net *rxnet = local->rxnet;
 714
 715         _enter("C=%x", conn->debug_id);
 716
 717         trace_rxrpc_client(conn, -1, rxrpc_client_cleanup);
 718         atomic_dec(&rxnet->nr_client_conns);
 719
 720         rxrpc_put_client_connection_id(local, conn);
 721 }
 722
 723 /*
 724  * Discard expired client connections from the idle list.  Each conn in the
 725  * idle list has been exposed and holds an extra ref because of that.
 726  *
 727  * This may be called from conn setup or from a work item so cannot be
 728  * considered non-reentrant.
 729  */
 730 void rxrpc_discard_expired_client_conns(struct rxrpc_local *local)
 731 {
 732         struct rxrpc_connection *conn;
 733         unsigned long expiry, conn_expires_at, now;
 734         unsigned int nr_conns;
 735
 736         _enter("");
 737
 738         /* We keep an estimate of what the number of conns ought to be after
 739          * we've discarded some so that we don't overdo the discarding.
 740          */
 741         nr_conns = atomic_read(&local->rxnet->nr_client_conns);
 742
 743 next:
 744         conn = list_first_entry_or_null(&local->idle_client_conns,
 745                                         struct rxrpc_connection, cache_link);
 746         if (!conn)
 747                 return;
 748
 749         if (!local->kill_all_client_conns) {
 750                 /* If the number of connections is over the reap limit, we
 751                  * expedite discard by reducing the expiry timeout.  We must,
 752                  * however, have at least a short grace period to be able to do
 753                  * final-ACK or ABORT retransmission.
 754                  */
 755                 expiry = rxrpc_conn_idle_client_expiry;
 756                 if (nr_conns > rxrpc_reap_client_connections)
 757                         expiry = rxrpc_conn_idle_client_fast_expiry;
 758                 if (conn->local->service_closed)
 759                         expiry = rxrpc_closed_conn_expiry * HZ;
 760
 761                 conn_expires_at = conn->idle_timestamp + expiry;
 762
 763                 now = READ_ONCE(jiffies);
 764                 if (time_after(conn_expires_at, now))
 765                         goto not_yet_expired;
 766         }
 767
 768         atomic_dec(&conn->active);
 769         trace_rxrpc_client(conn, -1, rxrpc_client_discard);
 770         list_del_init(&conn->cache_link);
 771
 772         rxrpc_unbundle_conn(conn);
 773         /* Drop the ->cache_link ref */
 774         rxrpc_put_connection(conn, rxrpc_conn_put_discard_idle);
 775
 776         nr_conns--;
 777         goto next;
 778
 779 not_yet_expired:
 780         /* The connection at the front of the queue hasn't yet expired, so
 781          * schedule the work item for that point if we discarded something.
 782          *
 783          * We don't worry if the work item is already scheduled - it can look
 784          * after rescheduling itself at a later time.  We could cancel it, but
 785          * then things get messier.
 786          */
 787         _debug("not yet");
 788         if (!local->kill_all_client_conns)
 789                 timer_reduce(&local->client_conn_reap_timer, conn_expires_at);
 790
 791         _leave("");
 792 }
 793
 794 /*
 795  * Clean up the client connections on a local endpoint.
 796  */
 797 void rxrpc_clean_up_local_conns(struct rxrpc_local *local)
 798 {
 799         struct rxrpc_connection *conn;
 800
 801         _enter("");
 802
 803         local->kill_all_client_conns = true;
 804
 805         del_timer_sync(&local->client_conn_reap_timer);
 806
 807         while ((conn = list_first_entry_or_null(&local->idle_client_conns,
 808                                                 struct rxrpc_connection, cache_link))) {
 809                 list_del_init(&conn->cache_link);
 810                 atomic_dec(&conn->active);
 811                 trace_rxrpc_client(conn, -1, rxrpc_client_discard);
 812                 rxrpc_unbundle_conn(conn);
 813                 rxrpc_put_connection(conn, rxrpc_conn_put_local_dead);
 814         }
 815
 816         _leave(" [culled]");
 817 }