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