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