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         INIT_LIST_HEAD(&conn->c_send_queue);
 151         INIT_LIST_HEAD(&conn->c_retrans);
 152
 153         ret = rds_cong_get_maps(conn);
 154         if (ret) {
 155                 kmem_cache_free(rds_conn_slab, conn);
 156                 conn = ERR_PTR(ret);
 157                 goto out;
 158         }
 159
 160         /*
 161          * This is where a connection becomes loopback.  If *any* RDS sockets
 162          * can bind to the destination address then we'd rather the messages
 163          * flow through loopback rather than either transport.
 164          */
 165         if (rds_trans_get_preferred(faddr)) {
 166                 conn->c_loopback = 1;
 167                 if (is_outgoing && trans->t_prefer_loopback) {
 168                         /* "outgoing" connection - and the transport
 169                          * says it wants the connection handled by the
 170                          * loopback transport. This is what TCP does.
 171                          */
 172                         trans = &rds_loop_transport;
 173                 }
 174         }
 175
 176         conn->c_trans = trans;
 177
 178         ret = trans->conn_alloc(conn, gfp);
 179         if (ret) {
 180                 kmem_cache_free(rds_conn_slab, conn);
 181                 conn = ERR_PTR(ret);
 182                 goto out;
 183         }
 184
 185         atomic_set(&conn->c_state, RDS_CONN_DOWN);
 186         conn->c_reconnect_jiffies = 0;
 187         INIT_DELAYED_WORK(&conn->c_send_w, rds_send_worker);
 188         INIT_DELAYED_WORK(&conn->c_recv_w, rds_recv_worker);
 189         INIT_DELAYED_WORK(&conn->c_conn_w, rds_connect_worker);
 190         INIT_WORK(&conn->c_down_w, rds_shutdown_worker);
 191         mutex_init(&conn->c_cm_lock);
 192         conn->c_flags = 0;
 193
 194         rdsdebug("allocated conn %p for %pI4 -> %pI4 over %s %s\n",
 195           conn, &laddr, &faddr,
 196           trans->t_name ? trans->t_name : "[unknown]",
 197           is_outgoing ? "(outgoing)" : "");
 198
 199         /*
 200          * Since we ran without holding the conn lock, someone could
 201          * have created the same conn (either normal or passive) in the
 202          * interim. We check while holding the lock. If we won, we complete
 203          * init and return our conn. If we lost, we rollback and return the
 204          * other one.
 205          */
 206         spin_lock_irqsave(&rds_conn_lock, flags);
 207         if (parent) {
 208                 /* Creating passive conn */
 209                 if (parent->c_passive) {
 210                         trans->conn_free(conn->c_transport_data);
 211                         kmem_cache_free(rds_conn_slab, conn);
 212                         conn = parent->c_passive;
 213                 } else {
 214                         parent->c_passive = conn;
 215                         rds_cong_add_conn(conn);
 216                         rds_conn_count++;
 217                 }
 218         } else {
 219                 /* Creating normal conn */
 220                 struct rds_connection *found;
 221
 222                 found = rds_conn_lookup(head, laddr, faddr, trans);
 223                 if (found) {
 224                         trans->conn_free(conn->c_transport_data);
 225                         kmem_cache_free(rds_conn_slab, conn);
 226                         conn = found;
 227                 } else {
 228                         hlist_add_head(&conn->c_hash_node, head);
 229                         rds_cong_add_conn(conn);
 230                         rds_conn_count++;
 231                 }
 232         }
 233         spin_unlock_irqrestore(&rds_conn_lock, flags);
 234
 235 out:
 236         return conn;
 237 }
 238
 239 struct rds_connection *rds_conn_create(__be32 laddr, __be32 faddr,
 240                                        struct rds_transport *trans, gfp_t gfp)
 241 {
 242         return __rds_conn_create(laddr, faddr, trans, gfp, 0);
 243 }
 244 EXPORT_SYMBOL_GPL(rds_conn_create);
 245
 246 struct rds_connection *rds_conn_create_outgoing(__be32 laddr, __be32 faddr,
 247                                        struct rds_transport *trans, gfp_t gfp)
 248 {
 249         return __rds_conn_create(laddr, faddr, trans, gfp, 1);
 250 }
 251 EXPORT_SYMBOL_GPL(rds_conn_create_outgoing);
 252
 253 void rds_conn_shutdown(struct rds_connection *conn)
 254 {
 255         /* shut it down unless it's down already */
 256         if (!rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_DOWN)) {
 257                 /*
 258                  * Quiesce the connection mgmt handlers before we start tearing
 259                  * things down. We don't hold the mutex for the entire
 260                  * duration of the shutdown operation, else we may be
 261                  * deadlocking with the CM handler. Instead, the CM event
 262                  * handler is supposed to check for state DISCONNECTING
 263                  */
 264                 mutex_lock(&conn->c_cm_lock);
 265                 if (!rds_conn_transition(conn, RDS_CONN_UP, RDS_CONN_DISCONNECTING)
 266                  && !rds_conn_transition(conn, RDS_CONN_ERROR, RDS_CONN_DISCONNECTING)) {
 267                         rds_conn_error(conn, "shutdown called in state %d\n",
 268                                         atomic_read(&conn->c_state));
 269                         mutex_unlock(&conn->c_cm_lock);
 270                         return;
 271                 }
 272                 mutex_unlock(&conn->c_cm_lock);
 273
 274                 /* verify everybody's out of rds_send_xmit() */
 275                 spin_lock_irq(&conn->c_send_lock);
 276                 spin_unlock_irq(&conn->c_send_lock);
 277
 278                 conn->c_trans->conn_shutdown(conn);
 279                 rds_conn_reset(conn);
 280
 281                 if (!rds_conn_transition(conn, RDS_CONN_DISCONNECTING, RDS_CONN_DOWN)) {
 282                         /* This can happen - eg when we're in the middle of tearing
 283                          * down the connection, and someone unloads the rds module.
 284                          * Quite reproduceable with loopback connections.
 285                          * Mostly harmless.
 286                          */
 287                         rds_conn_error(conn,
 288                                 "%s: failed to transition to state DOWN, "
 289                                 "current state is %d\n",
 290                                 __func__,
 291                                 atomic_read(&conn->c_state));
 292                         return;
 293                 }
 294         }
 295
 296         /* Then reconnect if it's still live.
 297          * The passive side of an IB loopback connection is never added
 298          * to the conn hash, so we never trigger a reconnect on this
 299          * conn - the reconnect is always triggered by the active peer. */
 300         cancel_delayed_work_sync(&conn->c_conn_w);
 301         if (!hlist_unhashed(&conn->c_hash_node))
 302                 rds_queue_reconnect(conn);
 303 }
 304
 305 /*
 306  * Stop and free a connection.
 307  */
 308 void rds_conn_destroy(struct rds_connection *conn)
 309 {
 310         struct rds_message *rm, *rtmp;
 311
 312         rdsdebug("freeing conn %p for %pI4 -> "
 313                  "%pI4\n", conn, &conn->c_laddr,
 314                  &conn->c_faddr);
 315
 316         hlist_del_init(&conn->c_hash_node);
 317
 318         /* wait for the rds thread to shut it down */
 319         atomic_set(&conn->c_state, RDS_CONN_ERROR);
 320         cancel_delayed_work(&conn->c_conn_w);
 321         queue_work(rds_wq, &conn->c_down_w);
 322         flush_workqueue(rds_wq);
 323
 324         /* tear down queued messages */
 325         list_for_each_entry_safe(rm, rtmp,
 326                                  &conn->c_send_queue,
 327                                  m_conn_item) {
 328                 list_del_init(&rm->m_conn_item);
 329                 BUG_ON(!list_empty(&rm->m_sock_item));
 330                 rds_message_put(rm);
 331         }
 332         if (conn->c_xmit_rm)
 333                 rds_message_put(conn->c_xmit_rm);
 334
 335         conn->c_trans->conn_free(conn->c_transport_data);
 336
 337         /*
 338          * The congestion maps aren't freed up here.  They're
 339          * freed by rds_cong_exit() after all the connections
 340          * have been freed.
 341          */
 342         rds_cong_remove_conn(conn);
 343
 344         BUG_ON(!list_empty(&conn->c_retrans));
 345         kmem_cache_free(rds_conn_slab, conn);
 346
 347         rds_conn_count--;
 348 }
 349 EXPORT_SYMBOL_GPL(rds_conn_destroy);
 350
 351 static void rds_conn_message_info(struct socket *sock, unsigned int len,
 352                                   struct rds_info_iterator *iter,
 353                                   struct rds_info_lengths *lens,
 354                                   int want_send)
 355 {
 356         struct hlist_head *head;
 357         struct hlist_node *pos;
 358         struct list_head *list;
 359         struct rds_connection *conn;
 360         struct rds_message *rm;
 361         unsigned long flags;
 362         unsigned int total = 0;
 363         size_t i;
 364
 365         len /= sizeof(struct rds_info_message);
 366
 367         spin_lock_irqsave(&rds_conn_lock, flags);
 368
 369         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 370              i++, head++) {
 371                 hlist_for_each_entry(conn, pos, head, c_hash_node) {
 372                         if (want_send)
 373                                 list = &conn->c_send_queue;
 374                         else
 375                                 list = &conn->c_retrans;
 376
 377                         spin_lock(&conn->c_lock);
 378
 379                         /* XXX too lazy to maintain counts.. */
 380                         list_for_each_entry(rm, list, m_conn_item) {
 381                                 total++;
 382                                 if (total <= len)
 383                                         rds_inc_info_copy(&rm->m_inc, iter,
 384                                                           conn->c_laddr,
 385                                                           conn->c_faddr, 0);
 386                         }
 387
 388                         spin_unlock(&conn->c_lock);
 389                 }
 390         }
 391
 392         spin_unlock_irqrestore(&rds_conn_lock, flags);
 393
 394         lens->nr = total;
 395         lens->each = sizeof(struct rds_info_message);
 396 }
 397
 398 static void rds_conn_message_info_send(struct socket *sock, unsigned int len,
 399                                        struct rds_info_iterator *iter,
 400                                        struct rds_info_lengths *lens)
 401 {
 402         rds_conn_message_info(sock, len, iter, lens, 1);
 403 }
 404
 405 static void rds_conn_message_info_retrans(struct socket *sock,
 406                                           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, 0);
 411 }
 412
 413 void rds_for_each_conn_info(struct socket *sock, unsigned int len,
 414                           struct rds_info_iterator *iter,
 415                           struct rds_info_lengths *lens,
 416                           int (*visitor)(struct rds_connection *, void *),
 417                           size_t item_len)
 418 {
 419         uint64_t buffer[(item_len + 7) / 8];
 420         struct hlist_head *head;
 421         struct hlist_node *pos;
 422         struct hlist_node *tmp;
 423         struct rds_connection *conn;
 424         unsigned long flags;
 425         size_t i;
 426
 427         spin_lock_irqsave(&rds_conn_lock, flags);
 428
 429         lens->nr = 0;
 430         lens->each = item_len;
 431
 432         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 433              i++, head++) {
 434                 hlist_for_each_entry_safe(conn, pos, tmp, head, c_hash_node) {
 435
 436                         /* XXX no c_lock usage.. */
 437                         if (!visitor(conn, buffer))
 438                                 continue;
 439
 440                         /* We copy as much as we can fit in the buffer,
 441                          * but we count all items so that the caller
 442                          * can resize the buffer. */
 443                         if (len >= item_len) {
 444                                 rds_info_copy(iter, buffer, item_len);
 445                                 len -= item_len;
 446                         }
 447                         lens->nr++;
 448                 }
 449         }
 450
 451         spin_unlock_irqrestore(&rds_conn_lock, flags);
 452 }
 453 EXPORT_SYMBOL_GPL(rds_for_each_conn_info);
 454
 455 static int rds_conn_info_visitor(struct rds_connection *conn,
 456                                   void *buffer)
 457 {
 458         struct rds_info_connection *cinfo = buffer;
 459
 460         cinfo->next_tx_seq = conn->c_next_tx_seq;
 461         cinfo->next_rx_seq = conn->c_next_rx_seq;
 462         cinfo->laddr = conn->c_laddr;
 463         cinfo->faddr = conn->c_faddr;
 464         strncpy(cinfo->transport, conn->c_trans->t_name,
 465                 sizeof(cinfo->transport));
 466         cinfo->flags = 0;
 467
 468         rds_conn_info_set(cinfo->flags,
 469                           spin_is_locked(&conn->c_send_lock), SENDING);
 470         /* XXX Future: return the state rather than these funky bits */
 471         rds_conn_info_set(cinfo->flags,
 472                           atomic_read(&conn->c_state) == RDS_CONN_CONNECTING,
 473                           CONNECTING);
 474         rds_conn_info_set(cinfo->flags,
 475                           atomic_read(&conn->c_state) == RDS_CONN_UP,
 476                           CONNECTED);
 477         return 1;
 478 }
 479
 480 static void rds_conn_info(struct socket *sock, unsigned int len,
 481                           struct rds_info_iterator *iter,
 482                           struct rds_info_lengths *lens)
 483 {
 484         rds_for_each_conn_info(sock, len, iter, lens,
 485                                 rds_conn_info_visitor,
 486                                 sizeof(struct rds_info_connection));
 487 }
 488
 489 int __init rds_conn_init(void)
 490 {
 491         rds_conn_slab = kmem_cache_create("rds_connection",
 492                                           sizeof(struct rds_connection),
 493                                           0, 0, NULL);
 494         if (!rds_conn_slab)
 495                 return -ENOMEM;
 496
 497         rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 498         rds_info_register_func(RDS_INFO_SEND_MESSAGES,
 499                                rds_conn_message_info_send);
 500         rds_info_register_func(RDS_INFO_RETRANS_MESSAGES,
 501                                rds_conn_message_info_retrans);
 502
 503         return 0;
 504 }
 505
 506 void rds_conn_exit(void)
 507 {
 508         rds_loop_exit();
 509
 510         WARN_ON(!hlist_empty(rds_conn_hash));
 511
 512         kmem_cache_destroy(rds_conn_slab);
 513
 514         rds_info_deregister_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 515         rds_info_deregister_func(RDS_INFO_SEND_MESSAGES,
 516                                  rds_conn_message_info_send);
 517         rds_info_deregister_func(RDS_INFO_RETRANS_MESSAGES,
 518                                  rds_conn_message_info_retrans);
 519 }
 520
 521 /*
 522  * Force a disconnect
 523  */
 524 void rds_conn_drop(struct rds_connection *conn)
 525 {
 526         atomic_set(&conn->c_state, RDS_CONN_ERROR);
 527         queue_work(rds_wq, &conn->c_down_w);
 528 }
 529 EXPORT_SYMBOL_GPL(rds_conn_drop);
 530
 531 /*
 532  * An error occurred on the connection
 533  */
 534 void
 535 __rds_conn_error(struct rds_connection *conn, const char *fmt, ...)
 536 {
 537         va_list ap;
 538
 539         va_start(ap, fmt);
 540         vprintk(fmt, ap);
 541         va_end(ap);
 542
 543         rds_conn_drop(conn);
 544 }