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 inline int rds_conn_is_sending(struct rds_connection *conn)
  66 {
  67         int ret = 0;
  68
  69         if (!mutex_trylock(&conn->c_send_lock))
  70                 ret = 1;
  71         else
  72                 mutex_unlock(&conn->c_send_lock);
  73
  74         return ret;
  75 }
  76
  77 static struct rds_connection *rds_conn_lookup(struct hlist_head *head,
  78                                               __be32 laddr, __be32 faddr,
  79                                               struct rds_transport *trans)
  80 {
  81         struct rds_connection *conn, *ret = NULL;
  82         struct hlist_node *pos;
  83
  84         hlist_for_each_entry(conn, pos, head, c_hash_node) {
  85                 if (conn->c_faddr == faddr && conn->c_laddr == laddr &&
  86                                 conn->c_trans == trans) {
  87                         ret = conn;
  88                         break;
  89                 }
  90         }
  91         rdsdebug("returning conn %p for %pI4 -> %pI4\n", ret,
  92                  &laddr, &faddr);
  93         return ret;
  94 }
  95
  96 /*
  97  * This is called by transports as they're bringing down a connection.
  98  * It clears partial message state so that the transport can start sending
  99  * and receiving over this connection again in the future.  It is up to
 100  * the transport to have serialized this call with its send and recv.
 101  */
 102 void rds_conn_reset(struct rds_connection *conn)
 103 {
 104         rdsdebug("connection %pI4 to %pI4 reset\n",
 105           &conn->c_laddr, &conn->c_faddr);
 106
 107         rds_stats_inc(s_conn_reset);
 108         rds_send_reset(conn);
 109         conn->c_flags = 0;
 110
 111         /* Do not clear next_rx_seq here, else we cannot distinguish
 112          * retransmitted packets from new packets, and will hand all
 113          * of them to the application. That is not consistent with the
 114          * reliability guarantees of RDS. */
 115 }
 116
 117 /*
 118  * There is only every one 'conn' for a given pair of addresses in the
 119  * system at a time.  They contain messages to be retransmitted and so
 120  * span the lifetime of the actual underlying transport connections.
 121  *
 122  * For now they are not garbage collected once they're created.  They
 123  * are torn down as the module is removed, if ever.
 124  */
 125 static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr,
 126                                        struct rds_transport *trans, gfp_t gfp,
 127                                        int is_outgoing)
 128 {
 129         struct rds_connection *conn, *parent = NULL;
 130         struct hlist_head *head = rds_conn_bucket(laddr, faddr);
 131         unsigned long flags;
 132         int ret;
 133
 134         spin_lock_irqsave(&rds_conn_lock, flags);
 135         conn = rds_conn_lookup(head, laddr, faddr, trans);
 136         if (conn && conn->c_loopback && conn->c_trans != &rds_loop_transport &&
 137             !is_outgoing) {
 138                 /* This is a looped back IB connection, and we're
 139                  * called by the code handling the incoming connect.
 140                  * We need a second connection object into which we
 141                  * can stick the other QP. */
 142                 parent = conn;
 143                 conn = parent->c_passive;
 144         }
 145         spin_unlock_irqrestore(&rds_conn_lock, flags);
 146         if (conn)
 147                 goto out;
 148
 149         conn = kmem_cache_zalloc(rds_conn_slab, gfp);
 150         if (!conn) {
 151                 conn = ERR_PTR(-ENOMEM);
 152                 goto out;
 153         }
 154
 155         INIT_HLIST_NODE(&conn->c_hash_node);
 156         conn->c_laddr = laddr;
 157         conn->c_faddr = faddr;
 158         spin_lock_init(&conn->c_lock);
 159         conn->c_next_tx_seq = 1;
 160
 161         mutex_init(&conn->c_send_lock);
 162         INIT_LIST_HEAD(&conn->c_send_queue);
 163         INIT_LIST_HEAD(&conn->c_retrans);
 164
 165         ret = rds_cong_get_maps(conn);
 166         if (ret) {
 167                 kmem_cache_free(rds_conn_slab, conn);
 168                 conn = ERR_PTR(ret);
 169                 goto out;
 170         }
 171
 172         /*
 173          * This is where a connection becomes loopback.  If *any* RDS sockets
 174          * can bind to the destination address then we'd rather the messages
 175          * flow through loopback rather than either transport.
 176          */
 177         if (rds_trans_get_preferred(faddr)) {
 178                 conn->c_loopback = 1;
 179                 if (is_outgoing && trans->t_prefer_loopback) {
 180                         /* "outgoing" connection - and the transport
 181                          * says it wants the connection handled by the
 182                          * loopback transport. This is what TCP does.
 183                          */
 184                         trans = &rds_loop_transport;
 185                 }
 186         }
 187
 188         conn->c_trans = trans;
 189
 190         ret = trans->conn_alloc(conn, gfp);
 191         if (ret) {
 192                 kmem_cache_free(rds_conn_slab, conn);
 193                 conn = ERR_PTR(ret);
 194                 goto out;
 195         }
 196
 197         atomic_set(&conn->c_state, RDS_CONN_DOWN);
 198         conn->c_reconnect_jiffies = 0;
 199         INIT_DELAYED_WORK(&conn->c_send_w, rds_send_worker);
 200         INIT_DELAYED_WORK(&conn->c_recv_w, rds_recv_worker);
 201         INIT_DELAYED_WORK(&conn->c_conn_w, rds_connect_worker);
 202         INIT_WORK(&conn->c_down_w, rds_shutdown_worker);
 203         mutex_init(&conn->c_cm_lock);
 204         conn->c_flags = 0;
 205
 206         rdsdebug("allocated conn %p for %pI4 -> %pI4 over %s %s\n",
 207           conn, &laddr, &faddr,
 208           trans->t_name ? trans->t_name : "[unknown]",
 209           is_outgoing ? "(outgoing)" : "");
 210
 211         /*
 212          * Since we ran without holding the conn lock, someone could
 213          * have created the same conn (either normal or passive) in the
 214          * interim. We check while holding the lock. If we won, we complete
 215          * init and return our conn. If we lost, we rollback and return the
 216          * other one.
 217          */
 218         spin_lock_irqsave(&rds_conn_lock, flags);
 219         if (parent) {
 220                 /* Creating passive conn */
 221                 if (parent->c_passive) {
 222                         trans->conn_free(conn->c_transport_data);
 223                         kmem_cache_free(rds_conn_slab, conn);
 224                         conn = parent->c_passive;
 225                 } else {
 226                         parent->c_passive = conn;
 227                         rds_cong_add_conn(conn);
 228                         rds_conn_count++;
 229                 }
 230         } else {
 231                 /* Creating normal conn */
 232                 struct rds_connection *found;
 233
 234                 found = rds_conn_lookup(head, laddr, faddr, trans);
 235                 if (found) {
 236                         trans->conn_free(conn->c_transport_data);
 237                         kmem_cache_free(rds_conn_slab, conn);
 238                         conn = found;
 239                 } else {
 240                         hlist_add_head(&conn->c_hash_node, head);
 241                         rds_cong_add_conn(conn);
 242                         rds_conn_count++;
 243                 }
 244         }
 245         spin_unlock_irqrestore(&rds_conn_lock, flags);
 246
 247 out:
 248         return conn;
 249 }
 250
 251 struct rds_connection *rds_conn_create(__be32 laddr, __be32 faddr,
 252                                        struct rds_transport *trans, gfp_t gfp)
 253 {
 254         return __rds_conn_create(laddr, faddr, trans, gfp, 0);
 255 }
 256 EXPORT_SYMBOL_GPL(rds_conn_create);
 257
 258 struct rds_connection *rds_conn_create_outgoing(__be32 laddr, __be32 faddr,
 259                                        struct rds_transport *trans, gfp_t gfp)
 260 {
 261         return __rds_conn_create(laddr, faddr, trans, gfp, 1);
 262 }
 263 EXPORT_SYMBOL_GPL(rds_conn_create_outgoing);
 264
 265 void rds_conn_shutdown(struct rds_connection *conn)
 266 {
 267         /* shut it down unless it's down already */
 268         if (!rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_DOWN)) {
 269                 /*
 270                  * Quiesce the connection mgmt handlers before we start tearing
 271                  * things down. We don't hold the mutex for the entire
 272                  * duration of the shutdown operation, else we may be
 273                  * deadlocking with the CM handler. Instead, the CM event
 274                  * handler is supposed to check for state DISCONNECTING
 275                  */
 276                 mutex_lock(&conn->c_cm_lock);
 277                 if (!rds_conn_transition(conn, RDS_CONN_UP, RDS_CONN_DISCONNECTING)
 278                  && !rds_conn_transition(conn, RDS_CONN_ERROR, RDS_CONN_DISCONNECTING)) {
 279                         rds_conn_error(conn, "shutdown called in state %d\n",
 280                                         atomic_read(&conn->c_state));
 281                         mutex_unlock(&conn->c_cm_lock);
 282                         return;
 283                 }
 284                 mutex_unlock(&conn->c_cm_lock);
 285
 286                 mutex_lock(&conn->c_send_lock);
 287                 conn->c_trans->conn_shutdown(conn);
 288                 rds_conn_reset(conn);
 289                 mutex_unlock(&conn->c_send_lock);
 290
 291                 if (!rds_conn_transition(conn, RDS_CONN_DISCONNECTING, RDS_CONN_DOWN)) {
 292                         /* This can happen - eg when we're in the middle of tearing
 293                          * down the connection, and someone unloads the rds module.
 294                          * Quite reproduceable with loopback connections.
 295                          * Mostly harmless.
 296                          */
 297                         rds_conn_error(conn,
 298                                 "%s: failed to transition to state DOWN, "
 299                                 "current state is %d\n",
 300                                 __func__,
 301                                 atomic_read(&conn->c_state));
 302                         return;
 303                 }
 304         }
 305
 306         /* Then reconnect if it's still live.
 307          * The passive side of an IB loopback connection is never added
 308          * to the conn hash, so we never trigger a reconnect on this
 309          * conn - the reconnect is always triggered by the active peer. */
 310         cancel_delayed_work_sync(&conn->c_conn_w);
 311         if (!hlist_unhashed(&conn->c_hash_node))
 312                 rds_queue_reconnect(conn);
 313 }
 314
 315 /*
 316  * Stop and free a connection.
 317  */
 318 void rds_conn_destroy(struct rds_connection *conn)
 319 {
 320         struct rds_message *rm, *rtmp;
 321
 322         rdsdebug("freeing conn %p for %pI4 -> "
 323                  "%pI4\n", conn, &conn->c_laddr,
 324                  &conn->c_faddr);
 325
 326         hlist_del_init(&conn->c_hash_node);
 327
 328         /* wait for the rds thread to shut it down */
 329         atomic_set(&conn->c_state, RDS_CONN_ERROR);
 330         cancel_delayed_work(&conn->c_conn_w);
 331         queue_work(rds_wq, &conn->c_down_w);
 332         flush_workqueue(rds_wq);
 333
 334         /* tear down queued messages */
 335         list_for_each_entry_safe(rm, rtmp,
 336                                  &conn->c_send_queue,
 337                                  m_conn_item) {
 338                 list_del_init(&rm->m_conn_item);
 339                 BUG_ON(!list_empty(&rm->m_sock_item));
 340                 rds_message_put(rm);
 341         }
 342         if (conn->c_xmit_rm)
 343                 rds_message_put(conn->c_xmit_rm);
 344
 345         conn->c_trans->conn_free(conn->c_transport_data);
 346
 347         /*
 348          * The congestion maps aren't freed up here.  They're
 349          * freed by rds_cong_exit() after all the connections
 350          * have been freed.
 351          */
 352         rds_cong_remove_conn(conn);
 353
 354         BUG_ON(!list_empty(&conn->c_retrans));
 355         kmem_cache_free(rds_conn_slab, conn);
 356
 357         rds_conn_count--;
 358 }
 359 EXPORT_SYMBOL_GPL(rds_conn_destroy);
 360
 361 static void rds_conn_message_info(struct socket *sock, unsigned int len,
 362                                   struct rds_info_iterator *iter,
 363                                   struct rds_info_lengths *lens,
 364                                   int want_send)
 365 {
 366         struct hlist_head *head;
 367         struct hlist_node *pos;
 368         struct list_head *list;
 369         struct rds_connection *conn;
 370         struct rds_message *rm;
 371         unsigned long flags;
 372         unsigned int total = 0;
 373         size_t i;
 374
 375         len /= sizeof(struct rds_info_message);
 376
 377         spin_lock_irqsave(&rds_conn_lock, flags);
 378
 379         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 380              i++, head++) {
 381                 hlist_for_each_entry(conn, pos, head, c_hash_node) {
 382                         if (want_send)
 383                                 list = &conn->c_send_queue;
 384                         else
 385                                 list = &conn->c_retrans;
 386
 387                         spin_lock(&conn->c_lock);
 388
 389                         /* XXX too lazy to maintain counts.. */
 390                         list_for_each_entry(rm, list, m_conn_item) {
 391                                 total++;
 392                                 if (total <= len)
 393                                         rds_inc_info_copy(&rm->m_inc, iter,
 394                                                           conn->c_laddr,
 395                                                           conn->c_faddr, 0);
 396                         }
 397
 398                         spin_unlock(&conn->c_lock);
 399                 }
 400         }
 401
 402         spin_unlock_irqrestore(&rds_conn_lock, flags);
 403
 404         lens->nr = total;
 405         lens->each = sizeof(struct rds_info_message);
 406 }
 407
 408 static void rds_conn_message_info_send(struct socket *sock, unsigned int len,
 409                                        struct rds_info_iterator *iter,
 410                                        struct rds_info_lengths *lens)
 411 {
 412         rds_conn_message_info(sock, len, iter, lens, 1);
 413 }
 414
 415 static void rds_conn_message_info_retrans(struct socket *sock,
 416                                           unsigned int len,
 417                                           struct rds_info_iterator *iter,
 418                                           struct rds_info_lengths *lens)
 419 {
 420         rds_conn_message_info(sock, len, iter, lens, 0);
 421 }
 422
 423 void rds_for_each_conn_info(struct socket *sock, unsigned int len,
 424                           struct rds_info_iterator *iter,
 425                           struct rds_info_lengths *lens,
 426                           int (*visitor)(struct rds_connection *, void *),
 427                           size_t item_len)
 428 {
 429         uint64_t buffer[(item_len + 7) / 8];
 430         struct hlist_head *head;
 431         struct hlist_node *pos;
 432         struct hlist_node *tmp;
 433         struct rds_connection *conn;
 434         unsigned long flags;
 435         size_t i;
 436
 437         spin_lock_irqsave(&rds_conn_lock, flags);
 438
 439         lens->nr = 0;
 440         lens->each = item_len;
 441
 442         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 443              i++, head++) {
 444                 hlist_for_each_entry_safe(conn, pos, tmp, head, c_hash_node) {
 445
 446                         /* XXX no c_lock usage.. */
 447                         if (!visitor(conn, buffer))
 448                                 continue;
 449
 450                         /* We copy as much as we can fit in the buffer,
 451                          * but we count all items so that the caller
 452                          * can resize the buffer. */
 453                         if (len >= item_len) {
 454                                 rds_info_copy(iter, buffer, item_len);
 455                                 len -= item_len;
 456                         }
 457                         lens->nr++;
 458                 }
 459         }
 460
 461         spin_unlock_irqrestore(&rds_conn_lock, flags);
 462 }
 463 EXPORT_SYMBOL_GPL(rds_for_each_conn_info);
 464
 465 static int rds_conn_info_visitor(struct rds_connection *conn,
 466                                   void *buffer)
 467 {
 468         struct rds_info_connection *cinfo = buffer;
 469
 470         cinfo->next_tx_seq = conn->c_next_tx_seq;
 471         cinfo->next_rx_seq = conn->c_next_rx_seq;
 472         cinfo->laddr = conn->c_laddr;
 473         cinfo->faddr = conn->c_faddr;
 474         strncpy(cinfo->transport, conn->c_trans->t_name,
 475                 sizeof(cinfo->transport));
 476         cinfo->flags = 0;
 477
 478         rds_conn_info_set(cinfo->flags,
 479                           rds_conn_is_sending(conn), SENDING);
 480         /* XXX Future: return the state rather than these funky bits */
 481         rds_conn_info_set(cinfo->flags,
 482                           atomic_read(&conn->c_state) == RDS_CONN_CONNECTING,
 483                           CONNECTING);
 484         rds_conn_info_set(cinfo->flags,
 485                           atomic_read(&conn->c_state) == RDS_CONN_UP,
 486                           CONNECTED);
 487         return 1;
 488 }
 489
 490 static void rds_conn_info(struct socket *sock, unsigned int len,
 491                           struct rds_info_iterator *iter,
 492                           struct rds_info_lengths *lens)
 493 {
 494         rds_for_each_conn_info(sock, len, iter, lens,
 495                                 rds_conn_info_visitor,
 496                                 sizeof(struct rds_info_connection));
 497 }
 498
 499 int __init rds_conn_init(void)
 500 {
 501         rds_conn_slab = kmem_cache_create("rds_connection",
 502                                           sizeof(struct rds_connection),
 503                                           0, 0, NULL);
 504         if (!rds_conn_slab)
 505                 return -ENOMEM;
 506
 507         rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 508         rds_info_register_func(RDS_INFO_SEND_MESSAGES,
 509                                rds_conn_message_info_send);
 510         rds_info_register_func(RDS_INFO_RETRANS_MESSAGES,
 511                                rds_conn_message_info_retrans);
 512
 513         return 0;
 514 }
 515
 516 void rds_conn_exit(void)
 517 {
 518         rds_loop_exit();
 519
 520         WARN_ON(!hlist_empty(rds_conn_hash));
 521
 522         kmem_cache_destroy(rds_conn_slab);
 523
 524         rds_info_deregister_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 525         rds_info_deregister_func(RDS_INFO_SEND_MESSAGES,
 526                                  rds_conn_message_info_send);
 527         rds_info_deregister_func(RDS_INFO_RETRANS_MESSAGES,
 528                                  rds_conn_message_info_retrans);
 529 }
 530
 531 /*
 532  * Force a disconnect
 533  */
 534 void rds_conn_drop(struct rds_connection *conn)
 535 {
 536         atomic_set(&conn->c_state, RDS_CONN_ERROR);
 537         queue_work(rds_wq, &conn->c_down_w);
 538 }
 539 EXPORT_SYMBOL_GPL(rds_conn_drop);
 540
 541 /*
 542  * An error occurred on the connection
 543  */
 544 void
 545 __rds_conn_error(struct rds_connection *conn, const char *fmt, ...)
 546 {
 547         va_list ap;
 548
 549         va_start(ap, fmt);
 550         vprintk(fmt, ap);
 551         va_end(ap);
 552
 553         rds_conn_drop(conn);
 554 }