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
 305                 conn->c_trans->conn_shutdown(conn);
 306                 rds_conn_reset(conn);
 307
 308                 if (!rds_conn_transition(conn, RDS_CONN_DISCONNECTING, RDS_CONN_DOWN)) {
 309                         /* This can happen - eg when we're in the middle of tearing
 310                          * down the connection, and someone unloads the rds module.
 311                          * Quite reproduceable with loopback connections.
 312                          * Mostly harmless.
 313                          */
 314                         rds_conn_error(conn,
 315                                 "%s: failed to transition to state DOWN, "
 316                                 "current state is %d\n",
 317                                 __func__,
 318                                 atomic_read(&conn->c_state));
 319                         return;
 320                 }
 321         }
 322
 323         /* Then reconnect if it's still live.
 324          * The passive side of an IB loopback connection is never added
 325          * to the conn hash, so we never trigger a reconnect on this
 326          * conn - the reconnect is always triggered by the active peer. */
 327         cancel_delayed_work_sync(&conn->c_conn_w);
 328         rcu_read_lock();
 329         if (!hlist_unhashed(&conn->c_hash_node)) {
 330                 rcu_read_unlock();
 331                 rds_queue_reconnect(conn);
 332         } else {
 333                 rcu_read_unlock();
 334         }
 335 }
 336
 337 /*
 338  * Stop and free a connection.
 339  *
 340  * This can only be used in very limited circumstances.  It assumes that once
 341  * the conn has been shutdown that no one else is referencing the connection.
 342  * We can only ensure this in the rmmod path in the current code.
 343  */
 344 void rds_conn_destroy(struct rds_connection *conn)
 345 {
 346         struct rds_message *rm, *rtmp;
 347         unsigned long flags;
 348
 349         rdsdebug("freeing conn %p for %pI4 -> "
 350                  "%pI4\n", conn, &conn->c_laddr,
 351                  &conn->c_faddr);
 352
 353         /* Ensure conn will not be scheduled for reconnect */
 354         spin_lock_irq(&rds_conn_lock);
 355         hlist_del_init_rcu(&conn->c_hash_node);
 356         spin_unlock_irq(&rds_conn_lock);
 357         synchronize_rcu();
 358
 359         /* shut the connection down */
 360         rds_conn_drop(conn);
 361         flush_work(&conn->c_down_w);
 362
 363         /* make sure lingering queued work won't try to ref the conn */
 364         cancel_delayed_work_sync(&conn->c_send_w);
 365         cancel_delayed_work_sync(&conn->c_recv_w);
 366
 367         /* tear down queued messages */
 368         list_for_each_entry_safe(rm, rtmp,
 369                                  &conn->c_send_queue,
 370                                  m_conn_item) {
 371                 list_del_init(&rm->m_conn_item);
 372                 BUG_ON(!list_empty(&rm->m_sock_item));
 373                 rds_message_put(rm);
 374         }
 375         if (conn->c_xmit_rm)
 376                 rds_message_put(conn->c_xmit_rm);
 377
 378         conn->c_trans->conn_free(conn->c_transport_data);
 379
 380         /*
 381          * The congestion maps aren't freed up here.  They're
 382          * freed by rds_cong_exit() after all the connections
 383          * have been freed.
 384          */
 385         rds_cong_remove_conn(conn);
 386
 387         BUG_ON(!list_empty(&conn->c_retrans));
 388         kmem_cache_free(rds_conn_slab, conn);
 389
 390         spin_lock_irqsave(&rds_conn_lock, flags);
 391         rds_conn_count--;
 392         spin_unlock_irqrestore(&rds_conn_lock, flags);
 393 }
 394 EXPORT_SYMBOL_GPL(rds_conn_destroy);
 395
 396 static void rds_conn_message_info(struct socket *sock, unsigned int len,
 397                                   struct rds_info_iterator *iter,
 398                                   struct rds_info_lengths *lens,
 399                                   int want_send)
 400 {
 401         struct hlist_head *head;
 402         struct list_head *list;
 403         struct rds_connection *conn;
 404         struct rds_message *rm;
 405         unsigned int total = 0;
 406         unsigned long flags;
 407         size_t i;
 408
 409         len /= sizeof(struct rds_info_message);
 410
 411         rcu_read_lock();
 412
 413         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 414              i++, head++) {
 415                 hlist_for_each_entry_rcu(conn, head, c_hash_node) {
 416                         if (want_send)
 417                                 list = &conn->c_send_queue;
 418                         else
 419                                 list = &conn->c_retrans;
 420
 421                         spin_lock_irqsave(&conn->c_lock, flags);
 422
 423                         /* XXX too lazy to maintain counts.. */
 424                         list_for_each_entry(rm, list, m_conn_item) {
 425                                 total++;
 426                                 if (total <= len)
 427                                         rds_inc_info_copy(&rm->m_inc, iter,
 428                                                           conn->c_laddr,
 429                                                           conn->c_faddr, 0);
 430                         }
 431
 432                         spin_unlock_irqrestore(&conn->c_lock, flags);
 433                 }
 434         }
 435         rcu_read_unlock();
 436
 437         lens->nr = total;
 438         lens->each = sizeof(struct rds_info_message);
 439 }
 440
 441 static void rds_conn_message_info_send(struct socket *sock, unsigned int len,
 442                                        struct rds_info_iterator *iter,
 443                                        struct rds_info_lengths *lens)
 444 {
 445         rds_conn_message_info(sock, len, iter, lens, 1);
 446 }
 447
 448 static void rds_conn_message_info_retrans(struct socket *sock,
 449                                           unsigned int len,
 450                                           struct rds_info_iterator *iter,
 451                                           struct rds_info_lengths *lens)
 452 {
 453         rds_conn_message_info(sock, len, iter, lens, 0);
 454 }
 455
 456 void rds_for_each_conn_info(struct socket *sock, unsigned int len,
 457                           struct rds_info_iterator *iter,
 458                           struct rds_info_lengths *lens,
 459                           int (*visitor)(struct rds_connection *, void *),
 460                           size_t item_len)
 461 {
 462         uint64_t buffer[(item_len + 7) / 8];
 463         struct hlist_head *head;
 464         struct rds_connection *conn;
 465         size_t i;
 466
 467         rcu_read_lock();
 468
 469         lens->nr = 0;
 470         lens->each = item_len;
 471
 472         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 473              i++, head++) {
 474                 hlist_for_each_entry_rcu(conn, head, c_hash_node) {
 475
 476                         /* XXX no c_lock usage.. */
 477                         if (!visitor(conn, buffer))
 478                                 continue;
 479
 480                         /* We copy as much as we can fit in the buffer,
 481                          * but we count all items so that the caller
 482                          * can resize the buffer. */
 483                         if (len >= item_len) {
 484                                 rds_info_copy(iter, buffer, item_len);
 485                                 len -= item_len;
 486                         }
 487                         lens->nr++;
 488                 }
 489         }
 490         rcu_read_unlock();
 491 }
 492 EXPORT_SYMBOL_GPL(rds_for_each_conn_info);
 493
 494 static int rds_conn_info_visitor(struct rds_connection *conn,
 495                                   void *buffer)
 496 {
 497         struct rds_info_connection *cinfo = buffer;
 498
 499         cinfo->next_tx_seq = conn->c_next_tx_seq;
 500         cinfo->next_rx_seq = conn->c_next_rx_seq;
 501         cinfo->laddr = conn->c_laddr;
 502         cinfo->faddr = conn->c_faddr;
 503         strncpy(cinfo->transport, conn->c_trans->t_name,
 504                 sizeof(cinfo->transport));
 505         cinfo->flags = 0;
 506
 507         rds_conn_info_set(cinfo->flags, test_bit(RDS_IN_XMIT, &conn->c_flags),
 508                           SENDING);
 509         /* XXX Future: return the state rather than these funky bits */
 510         rds_conn_info_set(cinfo->flags,
 511                           atomic_read(&conn->c_state) == RDS_CONN_CONNECTING,
 512                           CONNECTING);
 513         rds_conn_info_set(cinfo->flags,
 514                           atomic_read(&conn->c_state) == RDS_CONN_UP,
 515                           CONNECTED);
 516         return 1;
 517 }
 518
 519 static void rds_conn_info(struct socket *sock, unsigned int len,
 520                           struct rds_info_iterator *iter,
 521                           struct rds_info_lengths *lens)
 522 {
 523         rds_for_each_conn_info(sock, len, iter, lens,
 524                                 rds_conn_info_visitor,
 525                                 sizeof(struct rds_info_connection));
 526 }
 527
 528 int rds_conn_init(void)
 529 {
 530         rds_conn_slab = kmem_cache_create("rds_connection",
 531                                           sizeof(struct rds_connection),
 532                                           0, 0, NULL);
 533         if (!rds_conn_slab)
 534                 return -ENOMEM;
 535
 536         rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 537         rds_info_register_func(RDS_INFO_SEND_MESSAGES,
 538                                rds_conn_message_info_send);
 539         rds_info_register_func(RDS_INFO_RETRANS_MESSAGES,
 540                                rds_conn_message_info_retrans);
 541
 542         return 0;
 543 }
 544
 545 void rds_conn_exit(void)
 546 {
 547         rds_loop_exit();
 548
 549         WARN_ON(!hlist_empty(rds_conn_hash));
 550
 551         kmem_cache_destroy(rds_conn_slab);
 552
 553         rds_info_deregister_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 554         rds_info_deregister_func(RDS_INFO_SEND_MESSAGES,
 555                                  rds_conn_message_info_send);
 556         rds_info_deregister_func(RDS_INFO_RETRANS_MESSAGES,
 557                                  rds_conn_message_info_retrans);
 558 }
 559
 560 /*
 561  * Force a disconnect
 562  */
 563 void rds_conn_drop(struct rds_connection *conn)
 564 {
 565         atomic_set(&conn->c_state, RDS_CONN_ERROR);
 566         queue_work(rds_wq, &conn->c_down_w);
 567 }
 568 EXPORT_SYMBOL_GPL(rds_conn_drop);
 569
 570 /*
 571  * If the connection is down, trigger a connect. We may have scheduled a
 572  * delayed reconnect however - in this case we should not interfere.
 573  */
 574 void rds_conn_connect_if_down(struct rds_connection *conn)
 575 {
 576         if (rds_conn_state(conn) == RDS_CONN_DOWN &&
 577             !test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
 578                 queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
 579 }
 580 EXPORT_SYMBOL_GPL(rds_conn_connect_if_down);
 581
 582 /*
 583  * An error occurred on the connection
 584  */
 585 void
 586 __rds_conn_error(struct rds_connection *conn, const char *fmt, ...)
 587 {
 588         va_list ap;
 589
 590         va_start(ap, fmt);
 591         vprintk(fmt, ap);
 592         va_end(ap);
 593
 594         rds_conn_drop(conn);
 595 }