net/rds/connection.c

   1 /*
   2  * Copyright (c) 2006 Oracle.  All rights reserved.
   3  *
   4  * This software is available to you under a choice of one of two
   5  * licenses.  You may choose to be licensed under the terms of the GNU
   6  * General Public License (GPL) Version 2, available from the file
   7  * COPYING in the main directory of this source tree, or the
   8  * OpenIB.org BSD license below:
   9  *
  10  *     Redistribution and use in source and binary forms, with or
  11  *     without modification, are permitted provided that the following
  12  *     conditions are met:
  13  *
  14  *      - Redistributions of source code must retain the above
  15  *        copyright notice, this list of conditions and the following
  16  *        disclaimer.
  17  *
  18  *      - Redistributions in binary form must reproduce the above
  19  *        copyright notice, this list of conditions and the following
  20  *        disclaimer in the documentation and/or other materials
  21  *        provided with the distribution.
  22  *
  23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  30  * SOFTWARE.
  31  *
  32  */
  33 #include <linux/kernel.h>
  34 #include <linux/list.h>
  35 #include <linux/slab.h>
  36 #include <linux/export.h>
  37 #include <net/inet_hashtables.h>
  38
  39 #include "rds.h"
  40 #include "loop.h"
  41
  42 #define RDS_CONNECTION_HASH_BITS 12
  43 #define RDS_CONNECTION_HASH_ENTRIES (1 << RDS_CONNECTION_HASH_BITS)
  44 #define RDS_CONNECTION_HASH_MASK (RDS_CONNECTION_HASH_ENTRIES - 1)
  45
  46 /* converting this to RCU is a chore for another day.. */
  47 static DEFINE_SPINLOCK(rds_conn_lock);
  48 static unsigned long rds_conn_count;
  49 static struct hlist_head rds_conn_hash[RDS_CONNECTION_HASH_ENTRIES];
  50 static struct kmem_cache *rds_conn_slab;
  51
  52 static struct hlist_head *rds_conn_bucket(__be32 laddr, __be32 faddr)
  53 {
  54         static u32 rds_hash_secret __read_mostly;
  55
  56         unsigned long hash;
  57
  58         net_get_random_once(&rds_hash_secret, sizeof(rds_hash_secret));
  59
  60         /* Pass NULL, don't need struct net for hash */
  61         hash = __inet_ehashfn(be32_to_cpu(laddr), 0,
  62                               be32_to_cpu(faddr), 0,
  63                               rds_hash_secret);
  64         return &rds_conn_hash[hash & RDS_CONNECTION_HASH_MASK];
  65 }
  66
  67 #define rds_conn_info_set(var, test, suffix) do {               \
  68         if (test)                                               \
  69                 var |= RDS_INFO_CONNECTION_FLAG_##suffix;       \
  70 } while (0)
  71
  72 /* rcu read lock must be held or the connection spinlock */
  73 static struct rds_connection *rds_conn_lookup(struct net *net,
  74                                               struct hlist_head *head,
  75                                               __be32 laddr, __be32 faddr,
  76                                               struct rds_transport *trans)
  77 {
  78         struct rds_connection *conn, *ret = NULL;
  79
  80         hlist_for_each_entry_rcu(conn, head, c_hash_node) {
  81                 if (conn->c_faddr == faddr && conn->c_laddr == laddr &&
  82                     conn->c_trans == trans && net == rds_conn_net(conn)) {
  83                         ret = conn;
  84                         break;
  85                 }
  86         }
  87         rdsdebug("returning conn %p for %pI4 -> %pI4\n", ret,
  88                  &laddr, &faddr);
  89         return ret;
  90 }
  91
  92 /*
  93  * This is called by transports as they're bringing down a connection.
  94  * It clears partial message state so that the transport can start sending
  95  * and receiving over this connection again in the future.  It is up to
  96  * the transport to have serialized this call with its send and recv.
  97  */
  98 static void rds_conn_reset(struct rds_connection *conn)
  99 {
 100         rdsdebug("connection %pI4 to %pI4 reset\n",
 101           &conn->c_laddr, &conn->c_faddr);
 102
 103         rds_stats_inc(s_conn_reset);
 104         rds_send_reset(conn);
 105         conn->c_flags = 0;
 106
 107         /* Do not clear next_rx_seq here, else we cannot distinguish
 108          * retransmitted packets from new packets, and will hand all
 109          * of them to the application. That is not consistent with the
 110          * reliability guarantees of RDS. */
 111 }
 112
 113 /*
 114  * There is only every one 'conn' for a given pair of addresses in the
 115  * system at a time.  They contain messages to be retransmitted and so
 116  * span the lifetime of the actual underlying transport connections.
 117  *
 118  * For now they are not garbage collected once they're created.  They
 119  * are torn down as the module is removed, if ever.
 120  */
 121 static struct rds_connection *__rds_conn_create(struct net *net,
 122                                                 __be32 laddr, __be32 faddr,
 123                                        struct rds_transport *trans, gfp_t gfp,
 124                                        int is_outgoing)
 125 {
 126         struct rds_connection *conn, *parent = NULL;
 127         struct hlist_head *head = rds_conn_bucket(laddr, faddr);
 128         struct rds_transport *loop_trans;
 129         unsigned long flags;
 130         int ret;
 131         struct rds_transport *otrans = trans;
 132
 133         if (!is_outgoing && otrans->t_type == RDS_TRANS_TCP)
 134                 goto new_conn;
 135         rcu_read_lock();
 136         conn = rds_conn_lookup(net, head, laddr, faddr, trans);
 137         if (conn && conn->c_loopback && conn->c_trans != &rds_loop_transport &&
 138             laddr == faddr && !is_outgoing) {
 139                 /* This is a looped back IB connection, and we're
 140                  * called by the code handling the incoming connect.
 141                  * We need a second connection object into which we
 142                  * can stick the other QP. */
 143                 parent = conn;
 144                 conn = parent->c_passive;
 145         }
 146         rcu_read_unlock();
 147         if (conn)
 148                 goto out;
 149
 150 new_conn:
 151         conn = kmem_cache_zalloc(rds_conn_slab, gfp);
 152         if (!conn) {
 153                 conn = ERR_PTR(-ENOMEM);
 154                 goto out;
 155         }
 156
 157         INIT_HLIST_NODE(&conn->c_hash_node);
 158         conn->c_laddr = laddr;
 159         conn->c_faddr = faddr;
 160         spin_lock_init(&conn->c_lock);
 161         conn->c_next_tx_seq = 1;
 162         rds_conn_net_set(conn, net);
 163
 164         init_waitqueue_head(&conn->c_waitq);
 165         INIT_LIST_HEAD(&conn->c_send_queue);
 166         INIT_LIST_HEAD(&conn->c_retrans);
 167
 168         ret = rds_cong_get_maps(conn);
 169         if (ret) {
 170                 kmem_cache_free(rds_conn_slab, conn);
 171                 conn = ERR_PTR(ret);
 172                 goto out;
 173         }
 174
 175         /*
 176          * This is where a connection becomes loopback.  If *any* RDS sockets
 177          * can bind to the destination address then we'd rather the messages
 178          * flow through loopback rather than either transport.
 179          */
 180         loop_trans = rds_trans_get_preferred(net, faddr);
 181         if (loop_trans) {
 182                 rds_trans_put(loop_trans);
 183                 conn->c_loopback = 1;
 184                 if (is_outgoing && trans->t_prefer_loopback) {
 185                         /* "outgoing" connection - and the transport
 186                          * says it wants the connection handled by the
 187                          * loopback transport. This is what TCP does.
 188                          */
 189                         trans = &rds_loop_transport;
 190                 }
 191         }
 192
 193         if (trans == NULL) {
 194                 kmem_cache_free(rds_conn_slab, conn);
 195                 conn = ERR_PTR(-ENODEV);
 196                 goto out;
 197         }
 198
 199         conn->c_trans = trans;
 200
 201         ret = trans->conn_alloc(conn, gfp);
 202         if (ret) {
 203                 kmem_cache_free(rds_conn_slab, conn);
 204                 conn = ERR_PTR(ret);
 205                 goto out;
 206         }
 207
 208         atomic_set(&conn->c_state, RDS_CONN_DOWN);
 209         conn->c_send_gen = 0;
 210         conn->c_reconnect_jiffies = 0;
 211         INIT_DELAYED_WORK(&conn->c_send_w, rds_send_worker);
 212         INIT_DELAYED_WORK(&conn->c_recv_w, rds_recv_worker);
 213         INIT_DELAYED_WORK(&conn->c_conn_w, rds_connect_worker);
 214         INIT_WORK(&conn->c_down_w, rds_shutdown_worker);
 215         mutex_init(&conn->c_cm_lock);
 216         conn->c_flags = 0;
 217
 218         rdsdebug("allocated conn %p for %pI4 -> %pI4 over %s %s\n",
 219           conn, &laddr, &faddr,
 220           trans->t_name ? trans->t_name : "[unknown]",
 221           is_outgoing ? "(outgoing)" : "");
 222
 223         /*
 224          * Since we ran without holding the conn lock, someone could
 225          * have created the same conn (either normal or passive) in the
 226          * interim. We check while holding the lock. If we won, we complete
 227          * init and return our conn. If we lost, we rollback and return the
 228          * other one.
 229          */
 230         spin_lock_irqsave(&rds_conn_lock, flags);
 231         if (parent) {
 232                 /* Creating passive conn */
 233                 if (parent->c_passive) {
 234                         trans->conn_free(conn->c_transport_data);
 235                         kmem_cache_free(rds_conn_slab, conn);
 236                         conn = parent->c_passive;
 237                 } else {
 238                         parent->c_passive = conn;
 239                         rds_cong_add_conn(conn);
 240                         rds_conn_count++;
 241                 }
 242         } else {
 243                 /* Creating normal conn */
 244                 struct rds_connection *found;
 245
 246                 if (!is_outgoing && otrans->t_type == RDS_TRANS_TCP)
 247                         found = NULL;
 248                 else
 249                         found = rds_conn_lookup(net, head, laddr, faddr, trans);
 250                 if (found) {
 251                         trans->conn_free(conn->c_transport_data);
 252                         kmem_cache_free(rds_conn_slab, conn);
 253                         conn = found;
 254                 } else {
 255                         if ((is_outgoing && otrans->t_type == RDS_TRANS_TCP) ||
 256                             (otrans->t_type != RDS_TRANS_TCP)) {
 257                                 /* Only the active side should be added to
 258                                  * reconnect list for TCP.
 259                                  */
 260                                 hlist_add_head_rcu(&conn->c_hash_node, head);
 261                         }
 262                         rds_cong_add_conn(conn);
 263                         rds_conn_count++;
 264                 }
 265         }
 266         spin_unlock_irqrestore(&rds_conn_lock, flags);
 267
 268 out:
 269         return conn;
 270 }
 271
 272 struct rds_connection *rds_conn_create(struct net *net,
 273                                        __be32 laddr, __be32 faddr,
 274                                        struct rds_transport *trans, gfp_t gfp)
 275 {
 276         return __rds_conn_create(net, laddr, faddr, trans, gfp, 0);
 277 }
 278 EXPORT_SYMBOL_GPL(rds_conn_create);
 279
 280 struct rds_connection *rds_conn_create_outgoing(struct net *net,
 281                                                 __be32 laddr, __be32 faddr,
 282                                        struct rds_transport *trans, gfp_t gfp)
 283 {
 284         return __rds_conn_create(net, laddr, faddr, trans, gfp, 1);
 285 }
 286 EXPORT_SYMBOL_GPL(rds_conn_create_outgoing);
 287
 288 void rds_conn_shutdown(struct rds_connection *conn)
 289 {
 290         /* shut it down unless it's down already */
 291         if (!rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_DOWN)) {
 292                 /*
 293                  * Quiesce the connection mgmt handlers before we start tearing
 294                  * things down. We don't hold the mutex for the entire
 295                  * duration of the shutdown operation, else we may be
 296                  * deadlocking with the CM handler. Instead, the CM event
 297                  * handler is supposed to check for state DISCONNECTING
 298                  */
 299                 mutex_lock(&conn->c_cm_lock);
 300                 if (!rds_conn_transition(conn, RDS_CONN_UP, RDS_CONN_DISCONNECTING)
 301                  && !rds_conn_transition(conn, RDS_CONN_ERROR, RDS_CONN_DISCONNECTING)) {
 302                         rds_conn_error(conn, "shutdown called in state %d\n",
 303                                         atomic_read(&conn->c_state));
 304                         mutex_unlock(&conn->c_cm_lock);
 305                         return;
 306                 }
 307                 mutex_unlock(&conn->c_cm_lock);
 308
 309                 wait_event(conn->c_waitq,
 310                            !test_bit(RDS_IN_XMIT, &conn->c_flags));
 311                 wait_event(conn->c_waitq,
 312                            !test_bit(RDS_RECV_REFILL, &conn->c_flags));
 313
 314                 conn->c_trans->conn_shutdown(conn);
 315                 rds_conn_reset(conn);
 316
 317                 if (!rds_conn_transition(conn, RDS_CONN_DISCONNECTING, RDS_CONN_DOWN)) {
 318                         /* This can happen - eg when we're in the middle of tearing
 319                          * down the connection, and someone unloads the rds module.
 320                          * Quite reproduceable with loopback connections.
 321                          * Mostly harmless.
 322                          */
 323                         rds_conn_error(conn,
 324                                 "%s: failed to transition to state DOWN, "
 325                                 "current state is %d\n",
 326                                 __func__,
 327                                 atomic_read(&conn->c_state));
 328                         return;
 329                 }
 330         }
 331
 332         /* Then reconnect if it's still live.
 333          * The passive side of an IB loopback connection is never added
 334          * to the conn hash, so we never trigger a reconnect on this
 335          * conn - the reconnect is always triggered by the active peer. */
 336         cancel_delayed_work_sync(&conn->c_conn_w);
 337         rcu_read_lock();
 338         if (!hlist_unhashed(&conn->c_hash_node)) {
 339                 rcu_read_unlock();
 340                 rds_queue_reconnect(conn);
 341         } else {
 342                 rcu_read_unlock();
 343         }
 344 }
 345
 346 /*
 347  * Stop and free a connection.
 348  *
 349  * This can only be used in very limited circumstances.  It assumes that once
 350  * the conn has been shutdown that no one else is referencing the connection.
 351  * We can only ensure this in the rmmod path in the current code.
 352  */
 353 void rds_conn_destroy(struct rds_connection *conn)
 354 {
 355         struct rds_message *rm, *rtmp;
 356         unsigned long flags;
 357
 358         rdsdebug("freeing conn %p for %pI4 -> "
 359                  "%pI4\n", conn, &conn->c_laddr,
 360                  &conn->c_faddr);
 361
 362         /* Ensure conn will not be scheduled for reconnect */
 363         spin_lock_irq(&rds_conn_lock);
 364         hlist_del_init_rcu(&conn->c_hash_node);
 365         spin_unlock_irq(&rds_conn_lock);
 366         synchronize_rcu();
 367
 368         /* shut the connection down */
 369         rds_conn_drop(conn);
 370         flush_work(&conn->c_down_w);
 371
 372         /* make sure lingering queued work won't try to ref the conn */
 373         cancel_delayed_work_sync(&conn->c_send_w);
 374         cancel_delayed_work_sync(&conn->c_recv_w);
 375
 376         /* tear down queued messages */
 377         list_for_each_entry_safe(rm, rtmp,
 378                                  &conn->c_send_queue,
 379                                  m_conn_item) {
 380                 list_del_init(&rm->m_conn_item);
 381                 BUG_ON(!list_empty(&rm->m_sock_item));
 382                 rds_message_put(rm);
 383         }
 384         if (conn->c_xmit_rm)
 385                 rds_message_put(conn->c_xmit_rm);
 386
 387         conn->c_trans->conn_free(conn->c_transport_data);
 388
 389         /*
 390          * The congestion maps aren't freed up here.  They're
 391          * freed by rds_cong_exit() after all the connections
 392          * have been freed.
 393          */
 394         rds_cong_remove_conn(conn);
 395
 396         BUG_ON(!list_empty(&conn->c_retrans));
 397         kmem_cache_free(rds_conn_slab, conn);
 398
 399         spin_lock_irqsave(&rds_conn_lock, flags);
 400         rds_conn_count--;
 401         spin_unlock_irqrestore(&rds_conn_lock, flags);
 402 }
 403 EXPORT_SYMBOL_GPL(rds_conn_destroy);
 404
 405 static void rds_conn_message_info(struct socket *sock, unsigned int len,
 406                                   struct rds_info_iterator *iter,
 407                                   struct rds_info_lengths *lens,
 408                                   int want_send)
 409 {
 410         struct hlist_head *head;
 411         struct list_head *list;
 412         struct rds_connection *conn;
 413         struct rds_message *rm;
 414         unsigned int total = 0;
 415         unsigned long flags;
 416         size_t i;
 417
 418         len /= sizeof(struct rds_info_message);
 419
 420         rcu_read_lock();
 421
 422         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 423              i++, head++) {
 424                 hlist_for_each_entry_rcu(conn, head, c_hash_node) {
 425                         if (want_send)
 426                                 list = &conn->c_send_queue;
 427                         else
 428                                 list = &conn->c_retrans;
 429
 430                         spin_lock_irqsave(&conn->c_lock, flags);
 431
 432                         /* XXX too lazy to maintain counts.. */
 433                         list_for_each_entry(rm, list, m_conn_item) {
 434                                 total++;
 435                                 if (total <= len)
 436                                         rds_inc_info_copy(&rm->m_inc, iter,
 437                                                           conn->c_laddr,
 438                                                           conn->c_faddr, 0);
 439                         }
 440
 441                         spin_unlock_irqrestore(&conn->c_lock, flags);
 442                 }
 443         }
 444         rcu_read_unlock();
 445
 446         lens->nr = total;
 447         lens->each = sizeof(struct rds_info_message);
 448 }
 449
 450 static void rds_conn_message_info_send(struct socket *sock, unsigned int len,
 451                                        struct rds_info_iterator *iter,
 452                                        struct rds_info_lengths *lens)
 453 {
 454         rds_conn_message_info(sock, len, iter, lens, 1);
 455 }
 456
 457 static void rds_conn_message_info_retrans(struct socket *sock,
 458                                           unsigned int len,
 459                                           struct rds_info_iterator *iter,
 460                                           struct rds_info_lengths *lens)
 461 {
 462         rds_conn_message_info(sock, len, iter, lens, 0);
 463 }
 464
 465 void rds_for_each_conn_info(struct socket *sock, unsigned int len,
 466                           struct rds_info_iterator *iter,
 467                           struct rds_info_lengths *lens,
 468                           int (*visitor)(struct rds_connection *, void *),
 469                           size_t item_len)
 470 {
 471         uint64_t buffer[(item_len + 7) / 8];
 472         struct hlist_head *head;
 473         struct rds_connection *conn;
 474         size_t i;
 475
 476         rcu_read_lock();
 477
 478         lens->nr = 0;
 479         lens->each = item_len;
 480
 481         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 482              i++, head++) {
 483                 hlist_for_each_entry_rcu(conn, head, c_hash_node) {
 484
 485                         /* XXX no c_lock usage.. */
 486                         if (!visitor(conn, buffer))
 487                                 continue;
 488
 489                         /* We copy as much as we can fit in the buffer,
 490                          * but we count all items so that the caller
 491                          * can resize the buffer. */
 492                         if (len >= item_len) {
 493                                 rds_info_copy(iter, buffer, item_len);
 494                                 len -= item_len;
 495                         }
 496                         lens->nr++;
 497                 }
 498         }
 499         rcu_read_unlock();
 500 }
 501 EXPORT_SYMBOL_GPL(rds_for_each_conn_info);
 502
 503 static int rds_conn_info_visitor(struct rds_connection *conn,
 504                                   void *buffer)
 505 {
 506         struct rds_info_connection *cinfo = buffer;
 507
 508         cinfo->next_tx_seq = conn->c_next_tx_seq;
 509         cinfo->next_rx_seq = conn->c_next_rx_seq;
 510         cinfo->laddr = conn->c_laddr;
 511         cinfo->faddr = conn->c_faddr;
 512         strncpy(cinfo->transport, conn->c_trans->t_name,
 513                 sizeof(cinfo->transport));
 514         cinfo->flags = 0;
 515
 516         rds_conn_info_set(cinfo->flags, test_bit(RDS_IN_XMIT, &conn->c_flags),
 517                           SENDING);
 518         /* XXX Future: return the state rather than these funky bits */
 519         rds_conn_info_set(cinfo->flags,
 520                           atomic_read(&conn->c_state) == RDS_CONN_CONNECTING,
 521                           CONNECTING);
 522         rds_conn_info_set(cinfo->flags,
 523                           atomic_read(&conn->c_state) == RDS_CONN_UP,
 524                           CONNECTED);
 525         return 1;
 526 }
 527
 528 static void rds_conn_info(struct socket *sock, unsigned int len,
 529                           struct rds_info_iterator *iter,
 530                           struct rds_info_lengths *lens)
 531 {
 532         rds_for_each_conn_info(sock, len, iter, lens,
 533                                 rds_conn_info_visitor,
 534                                 sizeof(struct rds_info_connection));
 535 }
 536
 537 int rds_conn_init(void)
 538 {
 539         rds_conn_slab = kmem_cache_create("rds_connection",
 540                                           sizeof(struct rds_connection),
 541                                           0, 0, NULL);
 542         if (!rds_conn_slab)
 543                 return -ENOMEM;
 544
 545         rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 546         rds_info_register_func(RDS_INFO_SEND_MESSAGES,
 547                                rds_conn_message_info_send);
 548         rds_info_register_func(RDS_INFO_RETRANS_MESSAGES,
 549                                rds_conn_message_info_retrans);
 550
 551         return 0;
 552 }
 553
 554 void rds_conn_exit(void)
 555 {
 556         rds_loop_exit();
 557
 558         WARN_ON(!hlist_empty(rds_conn_hash));
 559
 560         kmem_cache_destroy(rds_conn_slab);
 561
 562         rds_info_deregister_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 563         rds_info_deregister_func(RDS_INFO_SEND_MESSAGES,
 564                                  rds_conn_message_info_send);
 565         rds_info_deregister_func(RDS_INFO_RETRANS_MESSAGES,
 566                                  rds_conn_message_info_retrans);
 567 }
 568
 569 /*
 570  * Force a disconnect
 571  */
 572 void rds_conn_drop(struct rds_connection *conn)
 573 {
 574         atomic_set(&conn->c_state, RDS_CONN_ERROR);
 575         queue_work(rds_wq, &conn->c_down_w);
 576 }
 577 EXPORT_SYMBOL_GPL(rds_conn_drop);
 578
 579 /*
 580  * If the connection is down, trigger a connect. We may have scheduled a
 581  * delayed reconnect however - in this case we should not interfere.
 582  */
 583 void rds_conn_connect_if_down(struct rds_connection *conn)
 584 {
 585         if (rds_conn_state(conn) == RDS_CONN_DOWN &&
 586             !test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
 587                 queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
 588 }
 589 EXPORT_SYMBOL_GPL(rds_conn_connect_if_down);
 590
 591 /*
 592  * An error occurred on the connection
 593  */
 594 void
 595 __rds_conn_error(struct rds_connection *conn, const char *fmt, ...)
 596 {
 597         va_list ap;
 598
 599         va_start(ap, fmt);
 600         vprintk(fmt, ap);
 601         va_end(ap);
 602
 603         rds_conn_drop(conn);
 604 }