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         int npaths = (trans->t_mp_capable ? RDS_MPATH_WORKERS : 1);
 155
 156         rcu_read_lock();
 157         conn = rds_conn_lookup(net, head, laddr, faddr, trans);
 158         if (conn && conn->c_loopback && conn->c_trans != &rds_loop_transport &&
 159             laddr == faddr && !is_outgoing) {
 160                 /* This is a looped back IB connection, and we're
 161                  * called by the code handling the incoming connect.
 162                  * We need a second connection object into which we
 163                  * can stick the other QP. */
 164                 parent = conn;
 165                 conn = parent->c_passive;
 166         }
 167         rcu_read_unlock();
 168         if (conn)
 169                 goto out;
 170
 171         conn = kmem_cache_zalloc(rds_conn_slab, gfp);
 172         if (!conn) {
 173                 conn = ERR_PTR(-ENOMEM);
 174                 goto out;
 175         }
 176         conn->c_path = kcalloc(npaths, sizeof(struct rds_conn_path), gfp);
 177         if (!conn->c_path) {
 178                 kmem_cache_free(rds_conn_slab, conn);
 179                 conn = ERR_PTR(-ENOMEM);
 180                 goto out;
 181         }
 182
 183         INIT_HLIST_NODE(&conn->c_hash_node);
 184         conn->c_laddr = laddr;
 185         conn->c_faddr = faddr;
 186
 187         rds_conn_net_set(conn, net);
 188
 189         ret = rds_cong_get_maps(conn);
 190         if (ret) {
 191                 kfree(conn->c_path);
 192                 kmem_cache_free(rds_conn_slab, conn);
 193                 conn = ERR_PTR(ret);
 194                 goto out;
 195         }
 196
 197         /*
 198          * This is where a connection becomes loopback.  If *any* RDS sockets
 199          * can bind to the destination address then we'd rather the messages
 200          * flow through loopback rather than either transport.
 201          */
 202         loop_trans = rds_trans_get_preferred(net, faddr);
 203         if (loop_trans) {
 204                 rds_trans_put(loop_trans);
 205                 conn->c_loopback = 1;
 206                 if (is_outgoing && trans->t_prefer_loopback) {
 207                         /* "outgoing" connection - and the transport
 208                          * says it wants the connection handled by the
 209                          * loopback transport. This is what TCP does.
 210                          */
 211                         trans = &rds_loop_transport;
 212                 }
 213         }
 214
 215         conn->c_trans = trans;
 216
 217         init_waitqueue_head(&conn->c_hs_waitq);
 218         for (i = 0; i < npaths; i++) {
 219                 __rds_conn_path_init(conn, &conn->c_path[i],
 220                                      is_outgoing);
 221                 conn->c_path[i].cp_index = i;
 222         }
 223         ret = trans->conn_alloc(conn, gfp);
 224         if (ret) {
 225                 kfree(conn->c_path);
 226                 kmem_cache_free(rds_conn_slab, conn);
 227                 conn = ERR_PTR(ret);
 228                 goto out;
 229         }
 230
 231         rdsdebug("allocated conn %p for %pI4 -> %pI4 over %s %s\n",
 232           conn, &laddr, &faddr,
 233           trans->t_name ? trans->t_name : "[unknown]",
 234           is_outgoing ? "(outgoing)" : "");
 235
 236         /*
 237          * Since we ran without holding the conn lock, someone could
 238          * have created the same conn (either normal or passive) in the
 239          * interim. We check while holding the lock. If we won, we complete
 240          * init and return our conn. If we lost, we rollback and return the
 241          * other one.
 242          */
 243         spin_lock_irqsave(&rds_conn_lock, flags);
 244         if (parent) {
 245                 /* Creating passive conn */
 246                 if (parent->c_passive) {
 247                         trans->conn_free(conn->c_path[0].cp_transport_data);
 248                         kfree(conn->c_path);
 249                         kmem_cache_free(rds_conn_slab, conn);
 250                         conn = parent->c_passive;
 251                 } else {
 252                         parent->c_passive = conn;
 253                         rds_cong_add_conn(conn);
 254                         rds_conn_count++;
 255                 }
 256         } else {
 257                 /* Creating normal conn */
 258                 struct rds_connection *found;
 259
 260                 found = rds_conn_lookup(net, head, laddr, faddr, trans);
 261                 if (found) {
 262                         struct rds_conn_path *cp;
 263                         int i;
 264
 265                         for (i = 0; i < npaths; i++) {
 266                                 cp = &conn->c_path[i];
 267                                 /* The ->conn_alloc invocation may have
 268                                  * allocated resource for all paths, so all
 269                                  * of them may have to be freed here.
 270                                  */
 271                                 if (cp->cp_transport_data)
 272                                         trans->conn_free(cp->cp_transport_data);
 273                         }
 274                         kfree(conn->c_path);
 275                         kmem_cache_free(rds_conn_slab, conn);
 276                         conn = found;
 277                 } else {
 278                         conn->c_my_gen_num = rds_gen_num;
 279                         conn->c_peer_gen_num = 0;
 280                         hlist_add_head_rcu(&conn->c_hash_node, head);
 281                         rds_cong_add_conn(conn);
 282                         rds_conn_count++;
 283                 }
 284         }
 285         spin_unlock_irqrestore(&rds_conn_lock, flags);
 286
 287 out:
 288         return conn;
 289 }
 290
 291 struct rds_connection *rds_conn_create(struct net *net,
 292                                        __be32 laddr, __be32 faddr,
 293                                        struct rds_transport *trans, gfp_t gfp)
 294 {
 295         return __rds_conn_create(net, laddr, faddr, trans, gfp, 0);
 296 }
 297 EXPORT_SYMBOL_GPL(rds_conn_create);
 298
 299 struct rds_connection *rds_conn_create_outgoing(struct net *net,
 300                                                 __be32 laddr, __be32 faddr,
 301                                        struct rds_transport *trans, gfp_t gfp)
 302 {
 303         return __rds_conn_create(net, laddr, faddr, trans, gfp, 1);
 304 }
 305 EXPORT_SYMBOL_GPL(rds_conn_create_outgoing);
 306
 307 void rds_conn_shutdown(struct rds_conn_path *cp)
 308 {
 309         struct rds_connection *conn = cp->cp_conn;
 310
 311         /* shut it down unless it's down already */
 312         if (!rds_conn_path_transition(cp, RDS_CONN_DOWN, RDS_CONN_DOWN)) {
 313                 /*
 314                  * Quiesce the connection mgmt handlers before we start tearing
 315                  * things down. We don't hold the mutex for the entire
 316                  * duration of the shutdown operation, else we may be
 317                  * deadlocking with the CM handler. Instead, the CM event
 318                  * handler is supposed to check for state DISCONNECTING
 319                  */
 320                 mutex_lock(&cp->cp_cm_lock);
 321                 if (!rds_conn_path_transition(cp, RDS_CONN_UP,
 322                                               RDS_CONN_DISCONNECTING) &&
 323                     !rds_conn_path_transition(cp, RDS_CONN_ERROR,
 324                                               RDS_CONN_DISCONNECTING)) {
 325                         rds_conn_path_error(cp,
 326                                             "shutdown called in state %d\n",
 327                                             atomic_read(&cp->cp_state));
 328                         mutex_unlock(&cp->cp_cm_lock);
 329                         return;
 330                 }
 331                 mutex_unlock(&cp->cp_cm_lock);
 332
 333                 wait_event(cp->cp_waitq,
 334                            !test_bit(RDS_IN_XMIT, &cp->cp_flags));
 335                 wait_event(cp->cp_waitq,
 336                            !test_bit(RDS_RECV_REFILL, &cp->cp_flags));
 337
 338                 conn->c_trans->conn_path_shutdown(cp);
 339                 rds_conn_path_reset(cp);
 340
 341                 if (!rds_conn_path_transition(cp, RDS_CONN_DISCONNECTING,
 342                                               RDS_CONN_DOWN) &&
 343                     !rds_conn_path_transition(cp, RDS_CONN_ERROR,
 344                                               RDS_CONN_DOWN)) {
 345                         /* This can happen - eg when we're in the middle of tearing
 346                          * down the connection, and someone unloads the rds module.
 347                          * Quite reproducible with loopback connections.
 348                          * Mostly harmless.
 349                          *
 350                          * Note that this also happens with rds-tcp because
 351                          * we could have triggered rds_conn_path_drop in irq
 352                          * mode from rds_tcp_state change on the receipt of
 353                          * a FIN, thus we need to recheck for RDS_CONN_ERROR
 354                          * here.
 355                          */
 356                         rds_conn_path_error(cp, "%s: failed to transition "
 357                                             "to state DOWN, current state "
 358                                             "is %d\n", __func__,
 359                                             atomic_read(&cp->cp_state));
 360                         return;
 361                 }
 362         }
 363
 364         /* Then reconnect if it's still live.
 365          * The passive side of an IB loopback connection is never added
 366          * to the conn hash, so we never trigger a reconnect on this
 367          * conn - the reconnect is always triggered by the active peer. */
 368         cancel_delayed_work_sync(&cp->cp_conn_w);
 369         rcu_read_lock();
 370         if (!hlist_unhashed(&conn->c_hash_node)) {
 371                 rcu_read_unlock();
 372                 rds_queue_reconnect(cp);
 373         } else {
 374                 rcu_read_unlock();
 375         }
 376 }
 377
 378 /* destroy a single rds_conn_path. rds_conn_destroy() iterates over
 379  * all paths using rds_conn_path_destroy()
 380  */
 381 static void rds_conn_path_destroy(struct rds_conn_path *cp)
 382 {
 383         struct rds_message *rm, *rtmp;
 384
 385         if (!cp->cp_transport_data)
 386                 return;
 387
 388         /* make sure lingering queued work won't try to ref the conn */
 389         cancel_delayed_work_sync(&cp->cp_send_w);
 390         cancel_delayed_work_sync(&cp->cp_recv_w);
 391
 392         rds_conn_path_drop(cp, true);
 393         flush_work(&cp->cp_down_w);
 394
 395         /* tear down queued messages */
 396         list_for_each_entry_safe(rm, rtmp,
 397                                  &cp->cp_send_queue,
 398                                  m_conn_item) {
 399                 list_del_init(&rm->m_conn_item);
 400                 BUG_ON(!list_empty(&rm->m_sock_item));
 401                 rds_message_put(rm);
 402         }
 403         if (cp->cp_xmit_rm)
 404                 rds_message_put(cp->cp_xmit_rm);
 405
 406         cp->cp_conn->c_trans->conn_free(cp->cp_transport_data);
 407 }
 408
 409 /*
 410  * Stop and free a connection.
 411  *
 412  * This can only be used in very limited circumstances.  It assumes that once
 413  * the conn has been shutdown that no one else is referencing the connection.
 414  * We can only ensure this in the rmmod path in the current code.
 415  */
 416 void rds_conn_destroy(struct rds_connection *conn)
 417 {
 418         unsigned long flags;
 419         int i;
 420         struct rds_conn_path *cp;
 421         int npaths = (conn->c_trans->t_mp_capable ? RDS_MPATH_WORKERS : 1);
 422
 423         rdsdebug("freeing conn %p for %pI4 -> "
 424                  "%pI4\n", conn, &conn->c_laddr,
 425                  &conn->c_faddr);
 426
 427         conn->c_destroy_in_prog = 1;
 428         /* Ensure conn will not be scheduled for reconnect */
 429         spin_lock_irq(&rds_conn_lock);
 430         hlist_del_init_rcu(&conn->c_hash_node);
 431         spin_unlock_irq(&rds_conn_lock);
 432         synchronize_rcu();
 433
 434         /* shut the connection down */
 435         for (i = 0; i < npaths; i++) {
 436                 cp = &conn->c_path[i];
 437                 rds_conn_path_destroy(cp);
 438                 BUG_ON(!list_empty(&cp->cp_retrans));
 439         }
 440
 441         /*
 442          * The congestion maps aren't freed up here.  They're
 443          * freed by rds_cong_exit() after all the connections
 444          * have been freed.
 445          */
 446         rds_cong_remove_conn(conn);
 447
 448         put_net(conn->c_net);
 449         kfree(conn->c_path);
 450         kmem_cache_free(rds_conn_slab, conn);
 451
 452         spin_lock_irqsave(&rds_conn_lock, flags);
 453         rds_conn_count--;
 454         spin_unlock_irqrestore(&rds_conn_lock, flags);
 455 }
 456 EXPORT_SYMBOL_GPL(rds_conn_destroy);
 457
 458 static void rds_conn_message_info(struct socket *sock, unsigned int len,
 459                                   struct rds_info_iterator *iter,
 460                                   struct rds_info_lengths *lens,
 461                                   int want_send)
 462 {
 463         struct hlist_head *head;
 464         struct list_head *list;
 465         struct rds_connection *conn;
 466         struct rds_message *rm;
 467         unsigned int total = 0;
 468         unsigned long flags;
 469         size_t i;
 470         int j;
 471
 472         len /= sizeof(struct rds_info_message);
 473
 474         rcu_read_lock();
 475
 476         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 477              i++, head++) {
 478                 hlist_for_each_entry_rcu(conn, head, c_hash_node) {
 479                         struct rds_conn_path *cp;
 480                         int npaths;
 481
 482                         npaths = (conn->c_trans->t_mp_capable ?
 483                                  RDS_MPATH_WORKERS : 1);
 484
 485                         for (j = 0; j < npaths; j++) {
 486                                 cp = &conn->c_path[j];
 487                                 if (want_send)
 488                                         list = &cp->cp_send_queue;
 489                                 else
 490                                         list = &cp->cp_retrans;
 491
 492                                 spin_lock_irqsave(&cp->cp_lock, flags);
 493
 494                                 /* XXX too lazy to maintain counts.. */
 495                                 list_for_each_entry(rm, list, m_conn_item) {
 496                                         total++;
 497                                         if (total <= len)
 498                                                 rds_inc_info_copy(&rm->m_inc,
 499                                                                   iter,
 500                                                                   conn->c_laddr,
 501                                                                   conn->c_faddr,
 502                                                                   0);
 503                                 }
 504
 505                                 spin_unlock_irqrestore(&cp->cp_lock, flags);
 506                         }
 507                 }
 508         }
 509         rcu_read_unlock();
 510
 511         lens->nr = total;
 512         lens->each = sizeof(struct rds_info_message);
 513 }
 514
 515 static void rds_conn_message_info_send(struct socket *sock, unsigned int len,
 516                                        struct rds_info_iterator *iter,
 517                                        struct rds_info_lengths *lens)
 518 {
 519         rds_conn_message_info(sock, len, iter, lens, 1);
 520 }
 521
 522 static void rds_conn_message_info_retrans(struct socket *sock,
 523                                           unsigned int len,
 524                                           struct rds_info_iterator *iter,
 525                                           struct rds_info_lengths *lens)
 526 {
 527         rds_conn_message_info(sock, len, iter, lens, 0);
 528 }
 529
 530 void rds_for_each_conn_info(struct socket *sock, unsigned int len,
 531                           struct rds_info_iterator *iter,
 532                           struct rds_info_lengths *lens,
 533                           int (*visitor)(struct rds_connection *, void *),
 534                           size_t item_len)
 535 {
 536         uint64_t buffer[(item_len + 7) / 8];
 537         struct hlist_head *head;
 538         struct rds_connection *conn;
 539         size_t i;
 540
 541         rcu_read_lock();
 542
 543         lens->nr = 0;
 544         lens->each = item_len;
 545
 546         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 547              i++, head++) {
 548                 hlist_for_each_entry_rcu(conn, head, c_hash_node) {
 549
 550                         /* XXX no c_lock usage.. */
 551                         if (!visitor(conn, buffer))
 552                                 continue;
 553
 554                         /* We copy as much as we can fit in the buffer,
 555                          * but we count all items so that the caller
 556                          * can resize the buffer. */
 557                         if (len >= item_len) {
 558                                 rds_info_copy(iter, buffer, item_len);
 559                                 len -= item_len;
 560                         }
 561                         lens->nr++;
 562                 }
 563         }
 564         rcu_read_unlock();
 565 }
 566 EXPORT_SYMBOL_GPL(rds_for_each_conn_info);
 567
 568 static void rds_walk_conn_path_info(struct socket *sock, unsigned int len,
 569                                     struct rds_info_iterator *iter,
 570                                     struct rds_info_lengths *lens,
 571                                     int (*visitor)(struct rds_conn_path *, void *),
 572                                     size_t item_len)
 573 {
 574         u64  buffer[(item_len + 7) / 8];
 575         struct hlist_head *head;
 576         struct rds_connection *conn;
 577         size_t i;
 578         int j;
 579
 580         rcu_read_lock();
 581
 582         lens->nr = 0;
 583         lens->each = item_len;
 584
 585         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 586              i++, head++) {
 587                 hlist_for_each_entry_rcu(conn, head, c_hash_node) {
 588                         struct rds_conn_path *cp;
 589                         int npaths;
 590
 591                         npaths = (conn->c_trans->t_mp_capable ?
 592                                  RDS_MPATH_WORKERS : 1);
 593                         for (j = 0; j < npaths; j++) {
 594                                 cp = &conn->c_path[j];
 595
 596                                 /* XXX no cp_lock usage.. */
 597                                 if (!visitor(cp, buffer))
 598                                         continue;
 599                         }
 600
 601                         /* We copy as much as we can fit in the buffer,
 602                          * but we count all items so that the caller
 603                          * can resize the buffer.
 604                          */
 605                         if (len >= item_len) {
 606                                 rds_info_copy(iter, buffer, item_len);
 607                                 len -= item_len;
 608                         }
 609                         lens->nr++;
 610                 }
 611         }
 612         rcu_read_unlock();
 613 }
 614
 615 static int rds_conn_info_visitor(struct rds_conn_path *cp, void *buffer)
 616 {
 617         struct rds_info_connection *cinfo = buffer;
 618
 619         cinfo->next_tx_seq = cp->cp_next_tx_seq;
 620         cinfo->next_rx_seq = cp->cp_next_rx_seq;
 621         cinfo->laddr = cp->cp_conn->c_laddr;
 622         cinfo->faddr = cp->cp_conn->c_faddr;
 623         strncpy(cinfo->transport, cp->cp_conn->c_trans->t_name,
 624                 sizeof(cinfo->transport));
 625         cinfo->flags = 0;
 626
 627         rds_conn_info_set(cinfo->flags, test_bit(RDS_IN_XMIT, &cp->cp_flags),
 628                           SENDING);
 629         /* XXX Future: return the state rather than these funky bits */
 630         rds_conn_info_set(cinfo->flags,
 631                           atomic_read(&cp->cp_state) == RDS_CONN_CONNECTING,
 632                           CONNECTING);
 633         rds_conn_info_set(cinfo->flags,
 634                           atomic_read(&cp->cp_state) == RDS_CONN_UP,
 635                           CONNECTED);
 636         return 1;
 637 }
 638
 639 static void rds_conn_info(struct socket *sock, unsigned int len,
 640                           struct rds_info_iterator *iter,
 641                           struct rds_info_lengths *lens)
 642 {
 643         rds_walk_conn_path_info(sock, len, iter, lens,
 644                                 rds_conn_info_visitor,
 645                                 sizeof(struct rds_info_connection));
 646 }
 647
 648 int rds_conn_init(void)
 649 {
 650         rds_conn_slab = kmem_cache_create("rds_connection",
 651                                           sizeof(struct rds_connection),
 652                                           0, 0, NULL);
 653         if (!rds_conn_slab)
 654                 return -ENOMEM;
 655
 656         rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 657         rds_info_register_func(RDS_INFO_SEND_MESSAGES,
 658                                rds_conn_message_info_send);
 659         rds_info_register_func(RDS_INFO_RETRANS_MESSAGES,
 660                                rds_conn_message_info_retrans);
 661
 662         return 0;
 663 }
 664
 665 void rds_conn_exit(void)
 666 {
 667         rds_loop_exit();
 668
 669         WARN_ON(!hlist_empty(rds_conn_hash));
 670
 671         kmem_cache_destroy(rds_conn_slab);
 672
 673         rds_info_deregister_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 674         rds_info_deregister_func(RDS_INFO_SEND_MESSAGES,
 675                                  rds_conn_message_info_send);
 676         rds_info_deregister_func(RDS_INFO_RETRANS_MESSAGES,
 677                                  rds_conn_message_info_retrans);
 678 }
 679
 680 /*
 681  * Force a disconnect
 682  */
 683 void rds_conn_path_drop(struct rds_conn_path *cp, bool destroy)
 684 {
 685         atomic_set(&cp->cp_state, RDS_CONN_ERROR);
 686
 687         if (!destroy && cp->cp_conn->c_destroy_in_prog)
 688                 return;
 689
 690         queue_work(rds_wq, &cp->cp_down_w);
 691 }
 692 EXPORT_SYMBOL_GPL(rds_conn_path_drop);
 693
 694 void rds_conn_drop(struct rds_connection *conn)
 695 {
 696         WARN_ON(conn->c_trans->t_mp_capable);
 697         rds_conn_path_drop(&conn->c_path[0], false);
 698 }
 699 EXPORT_SYMBOL_GPL(rds_conn_drop);
 700
 701 /*
 702  * If the connection is down, trigger a connect. We may have scheduled a
 703  * delayed reconnect however - in this case we should not interfere.
 704  */
 705 void rds_conn_path_connect_if_down(struct rds_conn_path *cp)
 706 {
 707         if (rds_conn_path_state(cp) == RDS_CONN_DOWN &&
 708             !test_and_set_bit(RDS_RECONNECT_PENDING, &cp->cp_flags))
 709                 queue_delayed_work(rds_wq, &cp->cp_conn_w, 0);
 710 }
 711 EXPORT_SYMBOL_GPL(rds_conn_path_connect_if_down);
 712
 713 void rds_conn_connect_if_down(struct rds_connection *conn)
 714 {
 715         WARN_ON(conn->c_trans->t_mp_capable);
 716         rds_conn_path_connect_if_down(&conn->c_path[0]);
 717 }
 718 EXPORT_SYMBOL_GPL(rds_conn_connect_if_down);
 719
 720 void
 721 __rds_conn_path_error(struct rds_conn_path *cp, const char *fmt, ...)
 722 {
 723         va_list ap;
 724
 725         va_start(ap, fmt);
 726         vprintk(fmt, ap);
 727         va_end(ap);
 728
 729         rds_conn_path_drop(cp, false);
 730 }