net/rds/connection.c

   1 /*
   2  * Copyright (c) 2006 Oracle.  All rights reserved.
   3  *
   4  * This software is available to you under a choice of one of two
   5  * licenses.  You may choose to be licensed under the terms of the GNU
   6  * General Public License (GPL) Version 2, available from the file
   7  * COPYING in the main directory of this source tree, or the
   8  * OpenIB.org BSD license below:
   9  *
  10  *     Redistribution and use in source and binary forms, with or
  11  *     without modification, are permitted provided that the following
  12  *     conditions are met:
  13  *
  14  *      - Redistributions of source code must retain the above
  15  *        copyright notice, this list of conditions and the following
  16  *        disclaimer.
  17  *
  18  *      - Redistributions in binary form must reproduce the above
  19  *        copyright notice, this list of conditions and the following
  20  *        disclaimer in the documentation and/or other materials
  21  *        provided with the distribution.
  22  *
  23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  30  * SOFTWARE.
  31  *
  32  */
  33 #include <linux/kernel.h>
  34 #include <linux/list.h>
  35 #include <linux/slab.h>
  36 #include <net/inet_hashtables.h>
  37
  38 #include "rds.h"
  39 #include "loop.h"
  40
  41 #define RDS_CONNECTION_HASH_BITS 12
  42 #define RDS_CONNECTION_HASH_ENTRIES (1 << RDS_CONNECTION_HASH_BITS)
  43 #define RDS_CONNECTION_HASH_MASK (RDS_CONNECTION_HASH_ENTRIES - 1)
  44
  45 /* converting this to RCU is a chore for another day.. */
  46 static DEFINE_SPINLOCK(rds_conn_lock);
  47 static unsigned long rds_conn_count;
  48 static struct hlist_head rds_conn_hash[RDS_CONNECTION_HASH_ENTRIES];
  49 static struct kmem_cache *rds_conn_slab;
  50
  51 static struct hlist_head *rds_conn_bucket(__be32 laddr, __be32 faddr)
  52 {
  53         /* Pass NULL, don't need struct net for hash */
  54         unsigned long hash = inet_ehashfn(NULL,
  55                                           be32_to_cpu(laddr), 0,
  56                                           be32_to_cpu(faddr), 0);
  57         return &rds_conn_hash[hash & RDS_CONNECTION_HASH_MASK];
  58 }
  59
  60 #define rds_conn_info_set(var, test, suffix) do {               \
  61         if (test)                                               \
  62                 var |= RDS_INFO_CONNECTION_FLAG_##suffix;       \
  63 } while (0)
  64
  65 /* rcu read lock must be held or the connection spinlock */
  66 static struct rds_connection *rds_conn_lookup(struct hlist_head *head,
  67                                               __be32 laddr, __be32 faddr,
  68                                               struct rds_transport *trans)
  69 {
  70         struct rds_connection *conn, *ret = NULL;
  71         struct hlist_node *pos;
  72
  73         hlist_for_each_entry_rcu(conn, pos, head, c_hash_node) {
  74                 if (conn->c_faddr == faddr && conn->c_laddr == laddr &&
  75                                 conn->c_trans == trans) {
  76                         ret = conn;
  77                         break;
  78                 }
  79         }
  80         rdsdebug("returning conn %p for %pI4 -> %pI4\n", ret,
  81                  &laddr, &faddr);
  82         return ret;
  83 }
  84
  85 /*
  86  * This is called by transports as they're bringing down a connection.
  87  * It clears partial message state so that the transport can start sending
  88  * and receiving over this connection again in the future.  It is up to
  89  * the transport to have serialized this call with its send and recv.
  90  */
  91 static void rds_conn_reset(struct rds_connection *conn)
  92 {
  93         rdsdebug("connection %pI4 to %pI4 reset\n",
  94           &conn->c_laddr, &conn->c_faddr);
  95
  96         rds_stats_inc(s_conn_reset);
  97         rds_send_reset(conn);
  98         conn->c_flags = 0;
  99
 100         /* Do not clear next_rx_seq here, else we cannot distinguish
 101          * retransmitted packets from new packets, and will hand all
 102          * of them to the application. That is not consistent with the
 103          * reliability guarantees of RDS. */
 104 }
 105
 106 /*
 107  * There is only every one 'conn' for a given pair of addresses in the
 108  * system at a time.  They contain messages to be retransmitted and so
 109  * span the lifetime of the actual underlying transport connections.
 110  *
 111  * For now they are not garbage collected once they're created.  They
 112  * are torn down as the module is removed, if ever.
 113  */
 114 static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr,
 115                                        struct rds_transport *trans, gfp_t gfp,
 116                                        int is_outgoing)
 117 {
 118         struct rds_connection *conn, *parent = NULL;
 119         struct hlist_head *head = rds_conn_bucket(laddr, faddr);
 120         struct rds_transport *loop_trans;
 121         unsigned long flags;
 122         int ret;
 123
 124         rcu_read_lock();
 125         conn = rds_conn_lookup(head, laddr, faddr, trans);
 126         if (conn && conn->c_loopback && conn->c_trans != &rds_loop_transport &&
 127             !is_outgoing) {
 128                 /* This is a looped back IB connection, and we're
 129                  * called by the code handling the incoming connect.
 130                  * We need a second connection object into which we
 131                  * can stick the other QP. */
 132                 parent = conn;
 133                 conn = parent->c_passive;
 134         }
 135         rcu_read_unlock();
 136         if (conn)
 137                 goto out;
 138
 139         conn = kmem_cache_zalloc(rds_conn_slab, gfp);
 140         if (!conn) {
 141                 conn = ERR_PTR(-ENOMEM);
 142                 goto out;
 143         }
 144
 145         INIT_HLIST_NODE(&conn->c_hash_node);
 146         conn->c_laddr = laddr;
 147         conn->c_faddr = faddr;
 148         spin_lock_init(&conn->c_lock);
 149         conn->c_next_tx_seq = 1;
 150
 151         init_waitqueue_head(&conn->c_waitq);
 152         INIT_LIST_HEAD(&conn->c_send_queue);
 153         INIT_LIST_HEAD(&conn->c_retrans);
 154
 155         ret = rds_cong_get_maps(conn);
 156         if (ret) {
 157                 kmem_cache_free(rds_conn_slab, conn);
 158                 conn = ERR_PTR(ret);
 159                 goto out;
 160         }
 161
 162         /*
 163          * This is where a connection becomes loopback.  If *any* RDS sockets
 164          * can bind to the destination address then we'd rather the messages
 165          * flow through loopback rather than either transport.
 166          */
 167         loop_trans = rds_trans_get_preferred(faddr);
 168         if (loop_trans) {
 169                 rds_trans_put(loop_trans);
 170                 conn->c_loopback = 1;
 171                 if (is_outgoing && trans->t_prefer_loopback) {
 172                         /* "outgoing" connection - and the transport
 173                          * says it wants the connection handled by the
 174                          * loopback transport. This is what TCP does.
 175                          */
 176                         trans = &rds_loop_transport;
 177                 }
 178         }
 179
 180         conn->c_trans = trans;
 181
 182         ret = trans->conn_alloc(conn, gfp);
 183         if (ret) {
 184                 kmem_cache_free(rds_conn_slab, conn);
 185                 conn = ERR_PTR(ret);
 186                 goto out;
 187         }
 188
 189         atomic_set(&conn->c_state, RDS_CONN_DOWN);
 190         conn->c_reconnect_jiffies = 0;
 191         INIT_DELAYED_WORK(&conn->c_send_w, rds_send_worker);
 192         INIT_DELAYED_WORK(&conn->c_recv_w, rds_recv_worker);
 193         INIT_DELAYED_WORK(&conn->c_conn_w, rds_connect_worker);
 194         INIT_WORK(&conn->c_down_w, rds_shutdown_worker);
 195         mutex_init(&conn->c_cm_lock);
 196         conn->c_flags = 0;
 197
 198         rdsdebug("allocated conn %p for %pI4 -> %pI4 over %s %s\n",
 199           conn, &laddr, &faddr,
 200           trans->t_name ? trans->t_name : "[unknown]",
 201           is_outgoing ? "(outgoing)" : "");
 202
 203         /*
 204          * Since we ran without holding the conn lock, someone could
 205          * have created the same conn (either normal or passive) in the
 206          * interim. We check while holding the lock. If we won, we complete
 207          * init and return our conn. If we lost, we rollback and return the
 208          * other one.
 209          */
 210         spin_lock_irqsave(&rds_conn_lock, flags);
 211         if (parent) {
 212                 /* Creating passive conn */
 213                 if (parent->c_passive) {
 214                         trans->conn_free(conn->c_transport_data);
 215                         kmem_cache_free(rds_conn_slab, conn);
 216                         conn = parent->c_passive;
 217                 } else {
 218                         parent->c_passive = conn;
 219                         rds_cong_add_conn(conn);
 220                         rds_conn_count++;
 221                 }
 222         } else {
 223                 /* Creating normal conn */
 224                 struct rds_connection *found;
 225
 226                 found = rds_conn_lookup(head, laddr, faddr, trans);
 227                 if (found) {
 228                         trans->conn_free(conn->c_transport_data);
 229                         kmem_cache_free(rds_conn_slab, conn);
 230                         conn = found;
 231                 } else {
 232                         hlist_add_head_rcu(&conn->c_hash_node, head);
 233                         rds_cong_add_conn(conn);
 234                         rds_conn_count++;
 235                 }
 236         }
 237         spin_unlock_irqrestore(&rds_conn_lock, flags);
 238
 239 out:
 240         return conn;
 241 }
 242
 243 struct rds_connection *rds_conn_create(__be32 laddr, __be32 faddr,
 244                                        struct rds_transport *trans, gfp_t gfp)
 245 {
 246         return __rds_conn_create(laddr, faddr, trans, gfp, 0);
 247 }
 248 EXPORT_SYMBOL_GPL(rds_conn_create);
 249
 250 struct rds_connection *rds_conn_create_outgoing(__be32 laddr, __be32 faddr,
 251                                        struct rds_transport *trans, gfp_t gfp)
 252 {
 253         return __rds_conn_create(laddr, faddr, trans, gfp, 1);
 254 }
 255 EXPORT_SYMBOL_GPL(rds_conn_create_outgoing);
 256
 257 void rds_conn_shutdown(struct rds_connection *conn)
 258 {
 259         /* shut it down unless it's down already */
 260         if (!rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_DOWN)) {
 261                 /*
 262                  * Quiesce the connection mgmt handlers before we start tearing
 263                  * things down. We don't hold the mutex for the entire
 264                  * duration of the shutdown operation, else we may be
 265                  * deadlocking with the CM handler. Instead, the CM event
 266                  * handler is supposed to check for state DISCONNECTING
 267                  */
 268                 mutex_lock(&conn->c_cm_lock);
 269                 if (!rds_conn_transition(conn, RDS_CONN_UP, RDS_CONN_DISCONNECTING)
 270                  && !rds_conn_transition(conn, RDS_CONN_ERROR, RDS_CONN_DISCONNECTING)) {
 271                         rds_conn_error(conn, "shutdown called in state %d\n",
 272                                         atomic_read(&conn->c_state));
 273                         mutex_unlock(&conn->c_cm_lock);
 274                         return;
 275                 }
 276                 mutex_unlock(&conn->c_cm_lock);
 277
 278                 wait_event(conn->c_waitq,
 279                            !test_bit(RDS_IN_XMIT, &conn->c_flags));
 280
 281                 conn->c_trans->conn_shutdown(conn);
 282                 rds_conn_reset(conn);
 283
 284                 if (!rds_conn_transition(conn, RDS_CONN_DISCONNECTING, RDS_CONN_DOWN)) {
 285                         /* This can happen - eg when we're in the middle of tearing
 286                          * down the connection, and someone unloads the rds module.
 287                          * Quite reproduceable with loopback connections.
 288                          * Mostly harmless.
 289                          */
 290                         rds_conn_error(conn,
 291                                 "%s: failed to transition to state DOWN, "
 292                                 "current state is %d\n",
 293                                 __func__,
 294                                 atomic_read(&conn->c_state));
 295                         return;
 296                 }
 297         }
 298
 299         /* Then reconnect if it's still live.
 300          * The passive side of an IB loopback connection is never added
 301          * to the conn hash, so we never trigger a reconnect on this
 302          * conn - the reconnect is always triggered by the active peer. */
 303         cancel_delayed_work_sync(&conn->c_conn_w);
 304         rcu_read_lock();
 305         if (!hlist_unhashed(&conn->c_hash_node)) {
 306                 rcu_read_unlock();
 307                 rds_queue_reconnect(conn);
 308         } else {
 309                 rcu_read_unlock();
 310         }
 311 }
 312
 313 /*
 314  * Stop and free a connection.
 315  *
 316  * This can only be used in very limited circumstances.  It assumes that once
 317  * the conn has been shutdown that no one else is referencing the connection.
 318  * We can only ensure this in the rmmod path in the current code.
 319  */
 320 void rds_conn_destroy(struct rds_connection *conn)
 321 {
 322         struct rds_message *rm, *rtmp;
 323         unsigned long flags;
 324
 325         rdsdebug("freeing conn %p for %pI4 -> "
 326                  "%pI4\n", conn, &conn->c_laddr,
 327                  &conn->c_faddr);
 328
 329         /* Ensure conn will not be scheduled for reconnect */
 330         spin_lock_irq(&rds_conn_lock);
 331         hlist_del_init_rcu(&conn->c_hash_node);
 332         spin_unlock_irq(&rds_conn_lock);
 333         synchronize_rcu();
 334
 335         /* shut the connection down */
 336         rds_conn_drop(conn);
 337         flush_work(&conn->c_down_w);
 338
 339         /* make sure lingering queued work won't try to ref the conn */
 340         cancel_delayed_work_sync(&conn->c_send_w);
 341         cancel_delayed_work_sync(&conn->c_recv_w);
 342
 343         /* tear down queued messages */
 344         list_for_each_entry_safe(rm, rtmp,
 345                                  &conn->c_send_queue,
 346                                  m_conn_item) {
 347                 list_del_init(&rm->m_conn_item);
 348                 BUG_ON(!list_empty(&rm->m_sock_item));
 349                 rds_message_put(rm);
 350         }
 351         if (conn->c_xmit_rm)
 352                 rds_message_put(conn->c_xmit_rm);
 353
 354         conn->c_trans->conn_free(conn->c_transport_data);
 355
 356         /*
 357          * The congestion maps aren't freed up here.  They're
 358          * freed by rds_cong_exit() after all the connections
 359          * have been freed.
 360          */
 361         rds_cong_remove_conn(conn);
 362
 363         BUG_ON(!list_empty(&conn->c_retrans));
 364         kmem_cache_free(rds_conn_slab, conn);
 365
 366         spin_lock_irqsave(&rds_conn_lock, flags);
 367         rds_conn_count--;
 368         spin_unlock_irqrestore(&rds_conn_lock, flags);
 369 }
 370 EXPORT_SYMBOL_GPL(rds_conn_destroy);
 371
 372 static void rds_conn_message_info(struct socket *sock, unsigned int len,
 373                                   struct rds_info_iterator *iter,
 374                                   struct rds_info_lengths *lens,
 375                                   int want_send)
 376 {
 377         struct hlist_head *head;
 378         struct hlist_node *pos;
 379         struct list_head *list;
 380         struct rds_connection *conn;
 381         struct rds_message *rm;
 382         unsigned int total = 0;
 383         unsigned long flags;
 384         size_t i;
 385
 386         len /= sizeof(struct rds_info_message);
 387
 388         rcu_read_lock();
 389
 390         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 391              i++, head++) {
 392                 hlist_for_each_entry_rcu(conn, pos, head, c_hash_node) {
 393                         if (want_send)
 394                                 list = &conn->c_send_queue;
 395                         else
 396                                 list = &conn->c_retrans;
 397
 398                         spin_lock_irqsave(&conn->c_lock, flags);
 399
 400                         /* XXX too lazy to maintain counts.. */
 401                         list_for_each_entry(rm, list, m_conn_item) {
 402                                 total++;
 403                                 if (total <= len)
 404                                         rds_inc_info_copy(&rm->m_inc, iter,
 405                                                           conn->c_laddr,
 406                                                           conn->c_faddr, 0);
 407                         }
 408
 409                         spin_unlock_irqrestore(&conn->c_lock, flags);
 410                 }
 411         }
 412         rcu_read_unlock();
 413
 414         lens->nr = total;
 415         lens->each = sizeof(struct rds_info_message);
 416 }
 417
 418 static void rds_conn_message_info_send(struct socket *sock, unsigned int len,
 419                                        struct rds_info_iterator *iter,
 420                                        struct rds_info_lengths *lens)
 421 {
 422         rds_conn_message_info(sock, len, iter, lens, 1);
 423 }
 424
 425 static void rds_conn_message_info_retrans(struct socket *sock,
 426                                           unsigned int len,
 427                                           struct rds_info_iterator *iter,
 428                                           struct rds_info_lengths *lens)
 429 {
 430         rds_conn_message_info(sock, len, iter, lens, 0);
 431 }
 432
 433 void rds_for_each_conn_info(struct socket *sock, unsigned int len,
 434                           struct rds_info_iterator *iter,
 435                           struct rds_info_lengths *lens,
 436                           int (*visitor)(struct rds_connection *, void *),
 437                           size_t item_len)
 438 {
 439         uint64_t buffer[(item_len + 7) / 8];
 440         struct hlist_head *head;
 441         struct hlist_node *pos;
 442         struct rds_connection *conn;
 443         size_t i;
 444
 445         rcu_read_lock();
 446
 447         lens->nr = 0;
 448         lens->each = item_len;
 449
 450         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 451              i++, head++) {
 452                 hlist_for_each_entry_rcu(conn, pos, head, c_hash_node) {
 453
 454                         /* XXX no c_lock usage.. */
 455                         if (!visitor(conn, buffer))
 456                                 continue;
 457
 458                         /* We copy as much as we can fit in the buffer,
 459                          * but we count all items so that the caller
 460                          * can resize the buffer. */
 461                         if (len >= item_len) {
 462                                 rds_info_copy(iter, buffer, item_len);
 463                                 len -= item_len;
 464                         }
 465                         lens->nr++;
 466                 }
 467         }
 468         rcu_read_unlock();
 469 }
 470 EXPORT_SYMBOL_GPL(rds_for_each_conn_info);
 471
 472 static int rds_conn_info_visitor(struct rds_connection *conn,
 473                                   void *buffer)
 474 {
 475         struct rds_info_connection *cinfo = buffer;
 476
 477         cinfo->next_tx_seq = conn->c_next_tx_seq;
 478         cinfo->next_rx_seq = conn->c_next_rx_seq;
 479         cinfo->laddr = conn->c_laddr;
 480         cinfo->faddr = conn->c_faddr;
 481         strncpy(cinfo->transport, conn->c_trans->t_name,
 482                 sizeof(cinfo->transport));
 483         cinfo->flags = 0;
 484
 485         rds_conn_info_set(cinfo->flags, test_bit(RDS_IN_XMIT, &conn->c_flags),
 486                           SENDING);
 487         /* XXX Future: return the state rather than these funky bits */
 488         rds_conn_info_set(cinfo->flags,
 489                           atomic_read(&conn->c_state) == RDS_CONN_CONNECTING,
 490                           CONNECTING);
 491         rds_conn_info_set(cinfo->flags,
 492                           atomic_read(&conn->c_state) == RDS_CONN_UP,
 493                           CONNECTED);
 494         return 1;
 495 }
 496
 497 static void rds_conn_info(struct socket *sock, unsigned int len,
 498                           struct rds_info_iterator *iter,
 499                           struct rds_info_lengths *lens)
 500 {
 501         rds_for_each_conn_info(sock, len, iter, lens,
 502                                 rds_conn_info_visitor,
 503                                 sizeof(struct rds_info_connection));
 504 }
 505
 506 int rds_conn_init(void)
 507 {
 508         rds_conn_slab = kmem_cache_create("rds_connection",
 509                                           sizeof(struct rds_connection),
 510                                           0, 0, NULL);
 511         if (!rds_conn_slab)
 512                 return -ENOMEM;
 513
 514         rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 515         rds_info_register_func(RDS_INFO_SEND_MESSAGES,
 516                                rds_conn_message_info_send);
 517         rds_info_register_func(RDS_INFO_RETRANS_MESSAGES,
 518                                rds_conn_message_info_retrans);
 519
 520         return 0;
 521 }
 522
 523 void rds_conn_exit(void)
 524 {
 525         rds_loop_exit();
 526
 527         WARN_ON(!hlist_empty(rds_conn_hash));
 528
 529         kmem_cache_destroy(rds_conn_slab);
 530
 531         rds_info_deregister_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 532         rds_info_deregister_func(RDS_INFO_SEND_MESSAGES,
 533                                  rds_conn_message_info_send);
 534         rds_info_deregister_func(RDS_INFO_RETRANS_MESSAGES,
 535                                  rds_conn_message_info_retrans);
 536 }
 537
 538 /*
 539  * Force a disconnect
 540  */
 541 void rds_conn_drop(struct rds_connection *conn)
 542 {
 543         atomic_set(&conn->c_state, RDS_CONN_ERROR);
 544         queue_work(rds_wq, &conn->c_down_w);
 545 }
 546 EXPORT_SYMBOL_GPL(rds_conn_drop);
 547
 548 /*
 549  * If the connection is down, trigger a connect. We may have scheduled a
 550  * delayed reconnect however - in this case we should not interfere.
 551  */
 552 void rds_conn_connect_if_down(struct rds_connection *conn)
 553 {
 554         if (rds_conn_state(conn) == RDS_CONN_DOWN &&
 555             !test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
 556                 queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
 557 }
 558 EXPORT_SYMBOL_GPL(rds_conn_connect_if_down);
 559
 560 /*
 561  * An error occurred on the connection
 562  */
 563 void
 564 __rds_conn_error(struct rds_connection *conn, const char *fmt, ...)
 565 {
 566         va_list ap;
 567
 568         va_start(ap, fmt);
 569         vprintk(fmt, ap);
 570         va_end(ap);
 571
 572         rds_conn_drop(conn);
 573 }