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_path_reset(struct rds_conn_path *cp)
  99 {
 100         struct rds_connection *conn = cp->cp_conn;
 101
 102         rdsdebug("connection %pI4 to %pI4 reset\n",
 103           &conn->c_laddr, &conn->c_faddr);
 104
 105         rds_stats_inc(s_conn_reset);
 106         rds_send_path_reset(cp);
 107         cp->cp_flags = 0;
 108
 109         /* Do not clear next_rx_seq here, else we cannot distinguish
 110          * retransmitted packets from new packets, and will hand all
 111          * of them to the application. That is not consistent with the
 112          * reliability guarantees of RDS. */
 113 }
 114
 115 static void __rds_conn_path_init(struct rds_connection *conn,
 116                                  struct rds_conn_path *cp, bool is_outgoing)
 117 {
 118         spin_lock_init(&cp->cp_lock);
 119         cp->cp_next_tx_seq = 1;
 120         init_waitqueue_head(&cp->cp_waitq);
 121         INIT_LIST_HEAD(&cp->cp_send_queue);
 122         INIT_LIST_HEAD(&cp->cp_retrans);
 123
 124         cp->cp_conn = conn;
 125         atomic_set(&cp->cp_state, RDS_CONN_DOWN);
 126         cp->cp_send_gen = 0;
 127         cp->cp_reconnect_jiffies = 0;
 128         INIT_DELAYED_WORK(&cp->cp_send_w, rds_send_worker);
 129         INIT_DELAYED_WORK(&cp->cp_recv_w, rds_recv_worker);
 130         INIT_DELAYED_WORK(&cp->cp_conn_w, rds_connect_worker);
 131         INIT_WORK(&cp->cp_down_w, rds_shutdown_worker);
 132         mutex_init(&cp->cp_cm_lock);
 133         cp->cp_flags = 0;
 134 }
 135
 136 /*
 137  * There is only every one 'conn' for a given pair of addresses in the
 138  * system at a time.  They contain messages to be retransmitted and so
 139  * span the lifetime of the actual underlying transport connections.
 140  *
 141  * For now they are not garbage collected once they're created.  They
 142  * are torn down as the module is removed, if ever.
 143  */
 144 static struct rds_connection *__rds_conn_create(struct net *net,
 145                                                 __be32 laddr, __be32 faddr,
 146                                        struct rds_transport *trans, gfp_t gfp,
 147                                        int is_outgoing)
 148 {
 149         struct rds_connection *conn, *parent = NULL;
 150         struct hlist_head *head = rds_conn_bucket(laddr, faddr);
 151         struct rds_transport *loop_trans;
 152         unsigned long flags;
 153         int ret, i;
 154
 155         rcu_read_lock();
 156         conn = rds_conn_lookup(net, head, laddr, faddr, trans);
 157         if (conn && conn->c_loopback && conn->c_trans != &rds_loop_transport &&
 158             laddr == faddr && !is_outgoing) {
 159                 /* This is a looped back IB connection, and we're
 160                  * called by the code handling the incoming connect.
 161                  * We need a second connection object into which we
 162                  * can stick the other QP. */
 163                 parent = conn;
 164                 conn = parent->c_passive;
 165         }
 166         rcu_read_unlock();
 167         if (conn)
 168                 goto out;
 169
 170         conn = kmem_cache_zalloc(rds_conn_slab, gfp);
 171         if (!conn) {
 172                 conn = ERR_PTR(-ENOMEM);
 173                 goto out;
 174         }
 175
 176         INIT_HLIST_NODE(&conn->c_hash_node);
 177         conn->c_laddr = laddr;
 178         conn->c_faddr = faddr;
 179
 180         rds_conn_net_set(conn, net);
 181
 182         ret = rds_cong_get_maps(conn);
 183         if (ret) {
 184                 kmem_cache_free(rds_conn_slab, conn);
 185                 conn = ERR_PTR(ret);
 186                 goto out;
 187         }
 188
 189         /*
 190          * This is where a connection becomes loopback.  If *any* RDS sockets
 191          * can bind to the destination address then we'd rather the messages
 192          * flow through loopback rather than either transport.
 193          */
 194         loop_trans = rds_trans_get_preferred(net, faddr);
 195         if (loop_trans) {
 196                 rds_trans_put(loop_trans);
 197                 conn->c_loopback = 1;
 198                 if (is_outgoing && trans->t_prefer_loopback) {
 199                         /* "outgoing" connection - and the transport
 200                          * says it wants the connection handled by the
 201                          * loopback transport. This is what TCP does.
 202                          */
 203                         trans = &rds_loop_transport;
 204                 }
 205         }
 206
 207         conn->c_trans = trans;
 208
 209         init_waitqueue_head(&conn->c_hs_waitq);
 210         for (i = 0; i < RDS_MPATH_WORKERS; i++) {
 211                 __rds_conn_path_init(conn, &conn->c_path[i],
 212                                      is_outgoing);
 213                 conn->c_path[i].cp_index = i;
 214         }
 215         ret = trans->conn_alloc(conn, gfp);
 216         if (ret) {
 217                 kmem_cache_free(rds_conn_slab, conn);
 218                 conn = ERR_PTR(ret);
 219                 goto out;
 220         }
 221
 222         rdsdebug("allocated conn %p for %pI4 -> %pI4 over %s %s\n",
 223           conn, &laddr, &faddr,
 224           trans->t_name ? trans->t_name : "[unknown]",
 225           is_outgoing ? "(outgoing)" : "");
 226
 227         /*
 228          * Since we ran without holding the conn lock, someone could
 229          * have created the same conn (either normal or passive) in the
 230          * interim. We check while holding the lock. If we won, we complete
 231          * init and return our conn. If we lost, we rollback and return the
 232          * other one.
 233          */
 234         spin_lock_irqsave(&rds_conn_lock, flags);
 235         if (parent) {
 236                 /* Creating passive conn */
 237                 if (parent->c_passive) {
 238                         trans->conn_free(conn->c_path[0].cp_transport_data);
 239                         kmem_cache_free(rds_conn_slab, conn);
 240                         conn = parent->c_passive;
 241                 } else {
 242                         parent->c_passive = conn;
 243                         rds_cong_add_conn(conn);
 244                         rds_conn_count++;
 245                 }
 246         } else {
 247                 /* Creating normal conn */
 248                 struct rds_connection *found;
 249
 250                 found = rds_conn_lookup(net, head, laddr, faddr, trans);
 251                 if (found) {
 252                         struct rds_conn_path *cp;
 253                         int i;
 254
 255                         for (i = 0; i < RDS_MPATH_WORKERS; i++) {
 256                                 cp = &conn->c_path[i];
 257                                 /* The ->conn_alloc invocation may have
 258                                  * allocated resource for all paths, so all
 259                                  * of them may have to be freed here.
 260                                  */
 261                                 if (cp->cp_transport_data)
 262                                         trans->conn_free(cp->cp_transport_data);
 263                         }
 264                         kmem_cache_free(rds_conn_slab, conn);
 265                         conn = found;
 266                 } else {
 267                         conn->c_my_gen_num = rds_gen_num;
 268                         conn->c_peer_gen_num = 0;
 269                         hlist_add_head_rcu(&conn->c_hash_node, head);
 270                         rds_cong_add_conn(conn);
 271                         rds_conn_count++;
 272                 }
 273         }
 274         spin_unlock_irqrestore(&rds_conn_lock, flags);
 275
 276 out:
 277         return conn;
 278 }
 279
 280 struct rds_connection *rds_conn_create(struct net *net,
 281                                        __be32 laddr, __be32 faddr,
 282                                        struct rds_transport *trans, gfp_t gfp)
 283 {
 284         return __rds_conn_create(net, laddr, faddr, trans, gfp, 0);
 285 }
 286 EXPORT_SYMBOL_GPL(rds_conn_create);
 287
 288 struct rds_connection *rds_conn_create_outgoing(struct net *net,
 289                                                 __be32 laddr, __be32 faddr,
 290                                        struct rds_transport *trans, gfp_t gfp)
 291 {
 292         return __rds_conn_create(net, laddr, faddr, trans, gfp, 1);
 293 }
 294 EXPORT_SYMBOL_GPL(rds_conn_create_outgoing);
 295
 296 void rds_conn_shutdown(struct rds_conn_path *cp)
 297 {
 298         struct rds_connection *conn = cp->cp_conn;
 299
 300         /* shut it down unless it's down already */
 301         if (!rds_conn_path_transition(cp, RDS_CONN_DOWN, RDS_CONN_DOWN)) {
 302                 /*
 303                  * Quiesce the connection mgmt handlers before we start tearing
 304                  * things down. We don't hold the mutex for the entire
 305                  * duration of the shutdown operation, else we may be
 306                  * deadlocking with the CM handler. Instead, the CM event
 307                  * handler is supposed to check for state DISCONNECTING
 308                  */
 309                 mutex_lock(&cp->cp_cm_lock);
 310                 if (!rds_conn_path_transition(cp, RDS_CONN_UP,
 311                                               RDS_CONN_DISCONNECTING) &&
 312                     !rds_conn_path_transition(cp, RDS_CONN_ERROR,
 313                                               RDS_CONN_DISCONNECTING)) {
 314                         rds_conn_path_error(cp,
 315                                             "shutdown called in state %d\n",
 316                                             atomic_read(&cp->cp_state));
 317                         mutex_unlock(&cp->cp_cm_lock);
 318                         return;
 319                 }
 320                 mutex_unlock(&cp->cp_cm_lock);
 321
 322                 wait_event(cp->cp_waitq,
 323                            !test_bit(RDS_IN_XMIT, &cp->cp_flags));
 324                 wait_event(cp->cp_waitq,
 325                            !test_bit(RDS_RECV_REFILL, &cp->cp_flags));
 326
 327                 conn->c_trans->conn_path_shutdown(cp);
 328                 rds_conn_path_reset(cp);
 329
 330                 if (!rds_conn_path_transition(cp, RDS_CONN_DISCONNECTING,
 331                                               RDS_CONN_DOWN) &&
 332                     !rds_conn_path_transition(cp, RDS_CONN_ERROR,
 333                                               RDS_CONN_DOWN)) {
 334                         /* This can happen - eg when we're in the middle of tearing
 335                          * down the connection, and someone unloads the rds module.
 336                          * Quite reproducible with loopback connections.
 337                          * Mostly harmless.
 338                          *
 339                          * Note that this also happens with rds-tcp because
 340                          * we could have triggered rds_conn_path_drop in irq
 341                          * mode from rds_tcp_state change on the receipt of
 342                          * a FIN, thus we need to recheck for RDS_CONN_ERROR
 343                          * here.
 344                          */
 345                         rds_conn_path_error(cp, "%s: failed to transition "
 346                                             "to state DOWN, current state "
 347                                             "is %d\n", __func__,
 348                                             atomic_read(&cp->cp_state));
 349                         return;
 350                 }
 351         }
 352
 353         /* Then reconnect if it's still live.
 354          * The passive side of an IB loopback connection is never added
 355          * to the conn hash, so we never trigger a reconnect on this
 356          * conn - the reconnect is always triggered by the active peer. */
 357         cancel_delayed_work_sync(&cp->cp_conn_w);
 358         rcu_read_lock();
 359         if (!hlist_unhashed(&conn->c_hash_node)) {
 360                 rcu_read_unlock();
 361                 rds_queue_reconnect(cp);
 362         } else {
 363                 rcu_read_unlock();
 364         }
 365 }
 366
 367 /* destroy a single rds_conn_path. rds_conn_destroy() iterates over
 368  * all paths using rds_conn_path_destroy()
 369  */
 370 static void rds_conn_path_destroy(struct rds_conn_path *cp)
 371 {
 372         struct rds_message *rm, *rtmp;
 373
 374         if (!cp->cp_transport_data)
 375                 return;
 376
 377         /* make sure lingering queued work won't try to ref the conn */
 378         cancel_delayed_work_sync(&cp->cp_send_w);
 379         cancel_delayed_work_sync(&cp->cp_recv_w);
 380
 381         rds_conn_path_drop(cp, true);
 382         flush_work(&cp->cp_down_w);
 383
 384         /* tear down queued messages */
 385         list_for_each_entry_safe(rm, rtmp,
 386                                  &cp->cp_send_queue,
 387                                  m_conn_item) {
 388                 list_del_init(&rm->m_conn_item);
 389                 BUG_ON(!list_empty(&rm->m_sock_item));
 390                 rds_message_put(rm);
 391         }
 392         if (cp->cp_xmit_rm)
 393                 rds_message_put(cp->cp_xmit_rm);
 394
 395         cp->cp_conn->c_trans->conn_free(cp->cp_transport_data);
 396 }
 397
 398 /*
 399  * Stop and free a connection.
 400  *
 401  * This can only be used in very limited circumstances.  It assumes that once
 402  * the conn has been shutdown that no one else is referencing the connection.
 403  * We can only ensure this in the rmmod path in the current code.
 404  */
 405 void rds_conn_destroy(struct rds_connection *conn)
 406 {
 407         unsigned long flags;
 408         int i;
 409         struct rds_conn_path *cp;
 410
 411         rdsdebug("freeing conn %p for %pI4 -> "
 412                  "%pI4\n", conn, &conn->c_laddr,
 413                  &conn->c_faddr);
 414
 415         conn->c_destroy_in_prog = 1;
 416         /* Ensure conn will not be scheduled for reconnect */
 417         spin_lock_irq(&rds_conn_lock);
 418         hlist_del_init_rcu(&conn->c_hash_node);
 419         spin_unlock_irq(&rds_conn_lock);
 420         synchronize_rcu();
 421
 422         /* shut the connection down */
 423         for (i = 0; i < RDS_MPATH_WORKERS; i++) {
 424                 cp = &conn->c_path[i];
 425                 rds_conn_path_destroy(cp);
 426                 BUG_ON(!list_empty(&cp->cp_retrans));
 427         }
 428
 429         /*
 430          * The congestion maps aren't freed up here.  They're
 431          * freed by rds_cong_exit() after all the connections
 432          * have been freed.
 433          */
 434         rds_cong_remove_conn(conn);
 435
 436         put_net(conn->c_net);
 437         kmem_cache_free(rds_conn_slab, conn);
 438
 439         spin_lock_irqsave(&rds_conn_lock, flags);
 440         rds_conn_count--;
 441         spin_unlock_irqrestore(&rds_conn_lock, flags);
 442 }
 443 EXPORT_SYMBOL_GPL(rds_conn_destroy);
 444
 445 static void rds_conn_message_info(struct socket *sock, unsigned int len,
 446                                   struct rds_info_iterator *iter,
 447                                   struct rds_info_lengths *lens,
 448                                   int want_send)
 449 {
 450         struct hlist_head *head;
 451         struct list_head *list;
 452         struct rds_connection *conn;
 453         struct rds_message *rm;
 454         unsigned int total = 0;
 455         unsigned long flags;
 456         size_t i;
 457         int j;
 458
 459         len /= sizeof(struct rds_info_message);
 460
 461         rcu_read_lock();
 462
 463         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 464              i++, head++) {
 465                 hlist_for_each_entry_rcu(conn, head, c_hash_node) {
 466                         struct rds_conn_path *cp;
 467
 468                         for (j = 0; j < RDS_MPATH_WORKERS; j++) {
 469                                 cp = &conn->c_path[j];
 470                                 if (want_send)
 471                                         list = &cp->cp_send_queue;
 472                                 else
 473                                         list = &cp->cp_retrans;
 474
 475                                 spin_lock_irqsave(&cp->cp_lock, flags);
 476
 477                                 /* XXX too lazy to maintain counts.. */
 478                                 list_for_each_entry(rm, list, m_conn_item) {
 479                                         total++;
 480                                         if (total <= len)
 481                                                 rds_inc_info_copy(&rm->m_inc,
 482                                                                   iter,
 483                                                                   conn->c_laddr,
 484                                                                   conn->c_faddr,
 485                                                                   0);
 486                                 }
 487
 488                                 spin_unlock_irqrestore(&cp->cp_lock, flags);
 489                                 if (!conn->c_trans->t_mp_capable)
 490                                         break;
 491                         }
 492                 }
 493         }
 494         rcu_read_unlock();
 495
 496         lens->nr = total;
 497         lens->each = sizeof(struct rds_info_message);
 498 }
 499
 500 static void rds_conn_message_info_send(struct socket *sock, unsigned int len,
 501                                        struct rds_info_iterator *iter,
 502                                        struct rds_info_lengths *lens)
 503 {
 504         rds_conn_message_info(sock, len, iter, lens, 1);
 505 }
 506
 507 static void rds_conn_message_info_retrans(struct socket *sock,
 508                                           unsigned int len,
 509                                           struct rds_info_iterator *iter,
 510                                           struct rds_info_lengths *lens)
 511 {
 512         rds_conn_message_info(sock, len, iter, lens, 0);
 513 }
 514
 515 void rds_for_each_conn_info(struct socket *sock, unsigned int len,
 516                           struct rds_info_iterator *iter,
 517                           struct rds_info_lengths *lens,
 518                           int (*visitor)(struct rds_connection *, void *),
 519                           size_t item_len)
 520 {
 521         uint64_t buffer[(item_len + 7) / 8];
 522         struct hlist_head *head;
 523         struct rds_connection *conn;
 524         size_t i;
 525
 526         rcu_read_lock();
 527
 528         lens->nr = 0;
 529         lens->each = item_len;
 530
 531         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 532              i++, head++) {
 533                 hlist_for_each_entry_rcu(conn, head, c_hash_node) {
 534
 535                         /* XXX no c_lock usage.. */
 536                         if (!visitor(conn, buffer))
 537                                 continue;
 538
 539                         /* We copy as much as we can fit in the buffer,
 540                          * but we count all items so that the caller
 541                          * can resize the buffer. */
 542                         if (len >= item_len) {
 543                                 rds_info_copy(iter, buffer, item_len);
 544                                 len -= item_len;
 545                         }
 546                         lens->nr++;
 547                 }
 548         }
 549         rcu_read_unlock();
 550 }
 551 EXPORT_SYMBOL_GPL(rds_for_each_conn_info);
 552
 553 static void rds_walk_conn_path_info(struct socket *sock, unsigned int len,
 554                                     struct rds_info_iterator *iter,
 555                                     struct rds_info_lengths *lens,
 556                                     int (*visitor)(struct rds_conn_path *, void *),
 557                                     size_t item_len)
 558 {
 559         u64  buffer[(item_len + 7) / 8];
 560         struct hlist_head *head;
 561         struct rds_connection *conn;
 562         size_t i;
 563         int j;
 564
 565         rcu_read_lock();
 566
 567         lens->nr = 0;
 568         lens->each = item_len;
 569
 570         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 571              i++, head++) {
 572                 hlist_for_each_entry_rcu(conn, head, c_hash_node) {
 573                         struct rds_conn_path *cp;
 574
 575                         for (j = 0; j < RDS_MPATH_WORKERS; j++) {
 576                                 cp = &conn->c_path[j];
 577
 578                                 /* XXX no cp_lock usage.. */
 579                                 if (!visitor(cp, buffer))
 580                                         continue;
 581                                 if (!conn->c_trans->t_mp_capable)
 582                                         break;
 583                         }
 584
 585                         /* We copy as much as we can fit in the buffer,
 586                          * but we count all items so that the caller
 587                          * can resize the buffer.
 588                          */
 589                         if (len >= item_len) {
 590                                 rds_info_copy(iter, buffer, item_len);
 591                                 len -= item_len;
 592                         }
 593                         lens->nr++;
 594                 }
 595         }
 596         rcu_read_unlock();
 597 }
 598
 599 static int rds_conn_info_visitor(struct rds_conn_path *cp, void *buffer)
 600 {
 601         struct rds_info_connection *cinfo = buffer;
 602
 603         cinfo->next_tx_seq = cp->cp_next_tx_seq;
 604         cinfo->next_rx_seq = cp->cp_next_rx_seq;
 605         cinfo->laddr = cp->cp_conn->c_laddr;
 606         cinfo->faddr = cp->cp_conn->c_faddr;
 607         strncpy(cinfo->transport, cp->cp_conn->c_trans->t_name,
 608                 sizeof(cinfo->transport));
 609         cinfo->flags = 0;
 610
 611         rds_conn_info_set(cinfo->flags, test_bit(RDS_IN_XMIT, &cp->cp_flags),
 612                           SENDING);
 613         /* XXX Future: return the state rather than these funky bits */
 614         rds_conn_info_set(cinfo->flags,
 615                           atomic_read(&cp->cp_state) == RDS_CONN_CONNECTING,
 616                           CONNECTING);
 617         rds_conn_info_set(cinfo->flags,
 618                           atomic_read(&cp->cp_state) == RDS_CONN_UP,
 619                           CONNECTED);
 620         return 1;
 621 }
 622
 623 static void rds_conn_info(struct socket *sock, unsigned int len,
 624                           struct rds_info_iterator *iter,
 625                           struct rds_info_lengths *lens)
 626 {
 627         rds_walk_conn_path_info(sock, len, iter, lens,
 628                                 rds_conn_info_visitor,
 629                                 sizeof(struct rds_info_connection));
 630 }
 631
 632 int rds_conn_init(void)
 633 {
 634         rds_conn_slab = kmem_cache_create("rds_connection",
 635                                           sizeof(struct rds_connection),
 636                                           0, 0, NULL);
 637         if (!rds_conn_slab)
 638                 return -ENOMEM;
 639
 640         rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 641         rds_info_register_func(RDS_INFO_SEND_MESSAGES,
 642                                rds_conn_message_info_send);
 643         rds_info_register_func(RDS_INFO_RETRANS_MESSAGES,
 644                                rds_conn_message_info_retrans);
 645
 646         return 0;
 647 }
 648
 649 void rds_conn_exit(void)
 650 {
 651         rds_loop_exit();
 652
 653         WARN_ON(!hlist_empty(rds_conn_hash));
 654
 655         kmem_cache_destroy(rds_conn_slab);
 656
 657         rds_info_deregister_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 658         rds_info_deregister_func(RDS_INFO_SEND_MESSAGES,
 659                                  rds_conn_message_info_send);
 660         rds_info_deregister_func(RDS_INFO_RETRANS_MESSAGES,
 661                                  rds_conn_message_info_retrans);
 662 }
 663
 664 /*
 665  * Force a disconnect
 666  */
 667 void rds_conn_path_drop(struct rds_conn_path *cp, bool destroy)
 668 {
 669         atomic_set(&cp->cp_state, RDS_CONN_ERROR);
 670
 671         if (!destroy && cp->cp_conn->c_destroy_in_prog)
 672                 return;
 673
 674         queue_work(rds_wq, &cp->cp_down_w);
 675 }
 676 EXPORT_SYMBOL_GPL(rds_conn_path_drop);
 677
 678 void rds_conn_drop(struct rds_connection *conn)
 679 {
 680         WARN_ON(conn->c_trans->t_mp_capable);
 681         rds_conn_path_drop(&conn->c_path[0], false);
 682 }
 683 EXPORT_SYMBOL_GPL(rds_conn_drop);
 684
 685 /*
 686  * If the connection is down, trigger a connect. We may have scheduled a
 687  * delayed reconnect however - in this case we should not interfere.
 688  */
 689 void rds_conn_path_connect_if_down(struct rds_conn_path *cp)
 690 {
 691         if (rds_conn_path_state(cp) == RDS_CONN_DOWN &&
 692             !test_and_set_bit(RDS_RECONNECT_PENDING, &cp->cp_flags))
 693                 queue_delayed_work(rds_wq, &cp->cp_conn_w, 0);
 694 }
 695 EXPORT_SYMBOL_GPL(rds_conn_path_connect_if_down);
 696
 697 void rds_conn_connect_if_down(struct rds_connection *conn)
 698 {
 699         WARN_ON(conn->c_trans->t_mp_capable);
 700         rds_conn_path_connect_if_down(&conn->c_path[0]);
 701 }
 702 EXPORT_SYMBOL_GPL(rds_conn_connect_if_down);
 703
 704 void
 705 __rds_conn_path_error(struct rds_conn_path *cp, const char *fmt, ...)
 706 {
 707         va_list ap;
 708
 709         va_start(ap, fmt);
 710         vprintk(fmt, ap);
 711         va_end(ap);
 712
 713         rds_conn_path_drop(cp, false);
 714 }