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