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