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 static struct rds_connection *rds_conn_lookup(struct hlist_head *head,
  66                                               __be32 laddr, __be32 faddr,
  67                                               struct rds_transport *trans)
  68 {
  69         struct rds_connection *conn, *ret = NULL;
  70         struct hlist_node *pos;
  71
  72         hlist_for_each_entry(conn, pos, head, c_hash_node) {
  73                 if (conn->c_faddr == faddr && conn->c_laddr == laddr &&
  74                                 conn->c_trans == trans) {
  75                         ret = conn;
  76                         break;
  77                 }
  78         }
  79         rdsdebug("returning conn %p for %pI4 -> %pI4\n", ret,
  80                  &laddr, &faddr);
  81         return ret;
  82 }
  83
  84 /*
  85  * This is called by transports as they're bringing down a connection.
  86  * It clears partial message state so that the transport can start sending
  87  * and receiving over this connection again in the future.  It is up to
  88  * the transport to have serialized this call with its send and recv.
  89  */
  90 void rds_conn_reset(struct rds_connection *conn)
  91 {
  92         rdsdebug("connection %pI4 to %pI4 reset\n",
  93           &conn->c_laddr, &conn->c_faddr);
  94
  95         rds_stats_inc(s_conn_reset);
  96         rds_send_reset(conn);
  97         conn->c_flags = 0;
  98
  99         /* Do not clear next_rx_seq here, else we cannot distinguish
 100          * retransmitted packets from new packets, and will hand all
 101          * of them to the application. That is not consistent with the
 102          * reliability guarantees of RDS. */
 103 }
 104
 105 /*
 106  * There is only every one 'conn' for a given pair of addresses in the
 107  * system at a time.  They contain messages to be retransmitted and so
 108  * span the lifetime of the actual underlying transport connections.
 109  *
 110  * For now they are not garbage collected once they're created.  They
 111  * are torn down as the module is removed, if ever.
 112  */
 113 static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr,
 114                                        struct rds_transport *trans, gfp_t gfp,
 115                                        int is_outgoing)
 116 {
 117         struct rds_connection *conn, *parent = NULL;
 118         struct hlist_head *head = rds_conn_bucket(laddr, faddr);
 119         unsigned long flags;
 120         int ret;
 121
 122         spin_lock_irqsave(&rds_conn_lock, flags);
 123         conn = rds_conn_lookup(head, laddr, faddr, trans);
 124         if (conn && conn->c_loopback && conn->c_trans != &rds_loop_transport &&
 125             !is_outgoing) {
 126                 /* This is a looped back IB connection, and we're
 127                  * called by the code handling the incoming connect.
 128                  * We need a second connection object into which we
 129                  * can stick the other QP. */
 130                 parent = conn;
 131                 conn = parent->c_passive;
 132         }
 133         spin_unlock_irqrestore(&rds_conn_lock, flags);
 134         if (conn)
 135                 goto out;
 136
 137         conn = kmem_cache_zalloc(rds_conn_slab, gfp);
 138         if (!conn) {
 139                 conn = ERR_PTR(-ENOMEM);
 140                 goto out;
 141         }
 142
 143         INIT_HLIST_NODE(&conn->c_hash_node);
 144         conn->c_laddr = laddr;
 145         conn->c_faddr = faddr;
 146         spin_lock_init(&conn->c_lock);
 147         conn->c_next_tx_seq = 1;
 148
 149         spin_lock_init(&conn->c_send_lock);
 150         atomic_set(&conn->c_send_generation, 1);
 151         atomic_set(&conn->c_senders, 0);
 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(&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                 /* verify everybody's out of rds_send_xmit() */
 277                 spin_lock_irq(&conn->c_send_lock);
 278                 spin_unlock_irq(&conn->c_send_lock);
 279
 280                 while(atomic_read(&conn->c_senders)) {
 281                         schedule_timeout(1);
 282                         spin_lock_irq(&conn->c_send_lock);
 283                         spin_unlock_irq(&conn->c_send_lock);
 284                 }
 285
 286                 conn->c_trans->conn_shutdown(conn);
 287                 rds_conn_reset(conn);
 288
 289                 if (!rds_conn_transition(conn, RDS_CONN_DISCONNECTING, RDS_CONN_DOWN)) {
 290                         /* This can happen - eg when we're in the middle of tearing
 291                          * down the connection, and someone unloads the rds module.
 292                          * Quite reproduceable with loopback connections.
 293                          * Mostly harmless.
 294                          */
 295                         rds_conn_error(conn,
 296                                 "%s: failed to transition to state DOWN, "
 297                                 "current state is %d\n",
 298                                 __func__,
 299                                 atomic_read(&conn->c_state));
 300                         return;
 301                 }
 302         }
 303
 304         /* Then reconnect if it's still live.
 305          * The passive side of an IB loopback connection is never added
 306          * to the conn hash, so we never trigger a reconnect on this
 307          * conn - the reconnect is always triggered by the active peer. */
 308         cancel_delayed_work_sync(&conn->c_conn_w);
 309         if (!hlist_unhashed(&conn->c_hash_node))
 310                 rds_queue_reconnect(conn);
 311 }
 312
 313 /*
 314  * Stop and free a connection.
 315  */
 316 void rds_conn_destroy(struct rds_connection *conn)
 317 {
 318         struct rds_message *rm, *rtmp;
 319
 320         rdsdebug("freeing conn %p for %pI4 -> "
 321                  "%pI4\n", conn, &conn->c_laddr,
 322                  &conn->c_faddr);
 323
 324         hlist_del_init(&conn->c_hash_node);
 325
 326         /* wait for the rds thread to shut it down */
 327         atomic_set(&conn->c_state, RDS_CONN_ERROR);
 328         cancel_delayed_work(&conn->c_conn_w);
 329         queue_work(rds_wq, &conn->c_down_w);
 330         flush_workqueue(rds_wq);
 331
 332         /* tear down queued messages */
 333         list_for_each_entry_safe(rm, rtmp,
 334                                  &conn->c_send_queue,
 335                                  m_conn_item) {
 336                 list_del_init(&rm->m_conn_item);
 337                 BUG_ON(!list_empty(&rm->m_sock_item));
 338                 rds_message_put(rm);
 339         }
 340         if (conn->c_xmit_rm)
 341                 rds_message_put(conn->c_xmit_rm);
 342
 343         conn->c_trans->conn_free(conn->c_transport_data);
 344
 345         /*
 346          * The congestion maps aren't freed up here.  They're
 347          * freed by rds_cong_exit() after all the connections
 348          * have been freed.
 349          */
 350         rds_cong_remove_conn(conn);
 351
 352         BUG_ON(!list_empty(&conn->c_retrans));
 353         kmem_cache_free(rds_conn_slab, conn);
 354
 355         rds_conn_count--;
 356 }
 357 EXPORT_SYMBOL_GPL(rds_conn_destroy);
 358
 359 static void rds_conn_message_info(struct socket *sock, unsigned int len,
 360                                   struct rds_info_iterator *iter,
 361                                   struct rds_info_lengths *lens,
 362                                   int want_send)
 363 {
 364         struct hlist_head *head;
 365         struct hlist_node *pos;
 366         struct list_head *list;
 367         struct rds_connection *conn;
 368         struct rds_message *rm;
 369         unsigned long flags;
 370         unsigned int total = 0;
 371         size_t i;
 372
 373         len /= sizeof(struct rds_info_message);
 374
 375         spin_lock_irqsave(&rds_conn_lock, flags);
 376
 377         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 378              i++, head++) {
 379                 hlist_for_each_entry(conn, pos, head, c_hash_node) {
 380                         if (want_send)
 381                                 list = &conn->c_send_queue;
 382                         else
 383                                 list = &conn->c_retrans;
 384
 385                         spin_lock(&conn->c_lock);
 386
 387                         /* XXX too lazy to maintain counts.. */
 388                         list_for_each_entry(rm, list, m_conn_item) {
 389                                 total++;
 390                                 if (total <= len)
 391                                         rds_inc_info_copy(&rm->m_inc, iter,
 392                                                           conn->c_laddr,
 393                                                           conn->c_faddr, 0);
 394                         }
 395
 396                         spin_unlock(&conn->c_lock);
 397                 }
 398         }
 399
 400         spin_unlock_irqrestore(&rds_conn_lock, flags);
 401
 402         lens->nr = total;
 403         lens->each = sizeof(struct rds_info_message);
 404 }
 405
 406 static void rds_conn_message_info_send(struct socket *sock, unsigned int len,
 407                                        struct rds_info_iterator *iter,
 408                                        struct rds_info_lengths *lens)
 409 {
 410         rds_conn_message_info(sock, len, iter, lens, 1);
 411 }
 412
 413 static void rds_conn_message_info_retrans(struct socket *sock,
 414                                           unsigned int len,
 415                                           struct rds_info_iterator *iter,
 416                                           struct rds_info_lengths *lens)
 417 {
 418         rds_conn_message_info(sock, len, iter, lens, 0);
 419 }
 420
 421 void rds_for_each_conn_info(struct socket *sock, unsigned int len,
 422                           struct rds_info_iterator *iter,
 423                           struct rds_info_lengths *lens,
 424                           int (*visitor)(struct rds_connection *, void *),
 425                           size_t item_len)
 426 {
 427         uint64_t buffer[(item_len + 7) / 8];
 428         struct hlist_head *head;
 429         struct hlist_node *pos;
 430         struct hlist_node *tmp;
 431         struct rds_connection *conn;
 432         unsigned long flags;
 433         size_t i;
 434
 435         spin_lock_irqsave(&rds_conn_lock, flags);
 436
 437         lens->nr = 0;
 438         lens->each = item_len;
 439
 440         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 441              i++, head++) {
 442                 hlist_for_each_entry_safe(conn, pos, tmp, head, c_hash_node) {
 443
 444                         /* XXX no c_lock usage.. */
 445                         if (!visitor(conn, buffer))
 446                                 continue;
 447
 448                         /* We copy as much as we can fit in the buffer,
 449                          * but we count all items so that the caller
 450                          * can resize the buffer. */
 451                         if (len >= item_len) {
 452                                 rds_info_copy(iter, buffer, item_len);
 453                                 len -= item_len;
 454                         }
 455                         lens->nr++;
 456                 }
 457         }
 458
 459         spin_unlock_irqrestore(&rds_conn_lock, flags);
 460 }
 461 EXPORT_SYMBOL_GPL(rds_for_each_conn_info);
 462
 463 static int rds_conn_info_visitor(struct rds_connection *conn,
 464                                   void *buffer)
 465 {
 466         struct rds_info_connection *cinfo = buffer;
 467
 468         cinfo->next_tx_seq = conn->c_next_tx_seq;
 469         cinfo->next_rx_seq = conn->c_next_rx_seq;
 470         cinfo->laddr = conn->c_laddr;
 471         cinfo->faddr = conn->c_faddr;
 472         strncpy(cinfo->transport, conn->c_trans->t_name,
 473                 sizeof(cinfo->transport));
 474         cinfo->flags = 0;
 475
 476         rds_conn_info_set(cinfo->flags,
 477                           spin_is_locked(&conn->c_send_lock), SENDING);
 478         /* XXX Future: return the state rather than these funky bits */
 479         rds_conn_info_set(cinfo->flags,
 480                           atomic_read(&conn->c_state) == RDS_CONN_CONNECTING,
 481                           CONNECTING);
 482         rds_conn_info_set(cinfo->flags,
 483                           atomic_read(&conn->c_state) == RDS_CONN_UP,
 484                           CONNECTED);
 485         return 1;
 486 }
 487
 488 static void rds_conn_info(struct socket *sock, unsigned int len,
 489                           struct rds_info_iterator *iter,
 490                           struct rds_info_lengths *lens)
 491 {
 492         rds_for_each_conn_info(sock, len, iter, lens,
 493                                 rds_conn_info_visitor,
 494                                 sizeof(struct rds_info_connection));
 495 }
 496
 497 int __init rds_conn_init(void)
 498 {
 499         rds_conn_slab = kmem_cache_create("rds_connection",
 500                                           sizeof(struct rds_connection),
 501                                           0, 0, NULL);
 502         if (!rds_conn_slab)
 503                 return -ENOMEM;
 504
 505         rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 506         rds_info_register_func(RDS_INFO_SEND_MESSAGES,
 507                                rds_conn_message_info_send);
 508         rds_info_register_func(RDS_INFO_RETRANS_MESSAGES,
 509                                rds_conn_message_info_retrans);
 510
 511         return 0;
 512 }
 513
 514 void rds_conn_exit(void)
 515 {
 516         rds_loop_exit();
 517
 518         WARN_ON(!hlist_empty(rds_conn_hash));
 519
 520         kmem_cache_destroy(rds_conn_slab);
 521
 522         rds_info_deregister_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 523         rds_info_deregister_func(RDS_INFO_SEND_MESSAGES,
 524                                  rds_conn_message_info_send);
 525         rds_info_deregister_func(RDS_INFO_RETRANS_MESSAGES,
 526                                  rds_conn_message_info_retrans);
 527 }
 528
 529 /*
 530  * Force a disconnect
 531  */
 532 void rds_conn_drop(struct rds_connection *conn)
 533 {
 534         atomic_set(&conn->c_state, RDS_CONN_ERROR);
 535         queue_work(rds_wq, &conn->c_down_w);
 536 }
 537 EXPORT_SYMBOL_GPL(rds_conn_drop);
 538
 539 /*
 540  * An error occurred on the connection
 541  */
 542 void
 543 __rds_conn_error(struct rds_connection *conn, const char *fmt, ...)
 544 {
 545         va_list ap;
 546
 547         va_start(ap, fmt);
 548         vprintk(fmt, ap);
 549         va_end(ap);
 550
 551         rds_conn_drop(conn);
 552 }