linux/net/rds/connection.c
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   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#include "rdma.h"
  41
  42#define RDS_CONNECTION_HASH_BITS 12
  43#define RDS_CONNECTION_HASH_ENTRIES (1 << RDS_CONNECTION_HASH_BITS)
  44#define RDS_CONNECTION_HASH_MASK (RDS_CONNECTION_HASH_ENTRIES - 1)
  45
  46/* converting this to RCU is a chore for another day.. */
  47static DEFINE_SPINLOCK(rds_conn_lock);
  48static unsigned long rds_conn_count;
  49static struct hlist_head rds_conn_hash[RDS_CONNECTION_HASH_ENTRIES];
  50static struct kmem_cache *rds_conn_slab;
  51
  52static struct hlist_head *rds_conn_bucket(__be32 laddr, __be32 faddr)
  53{
  54        /* Pass NULL, don't need struct net for hash */
  55        unsigned long hash = inet_ehashfn(NULL,
  56                                          be32_to_cpu(laddr), 0,
  57                                          be32_to_cpu(faddr), 0);
  58        return &rds_conn_hash[hash & RDS_CONNECTION_HASH_MASK];
  59}
  60
  61#define rds_conn_info_set(var, test, suffix) do {               \
  62        if (test)                                               \
  63                var |= RDS_INFO_CONNECTION_FLAG_##suffix;       \
  64} while (0)
  65
  66static inline int rds_conn_is_sending(struct rds_connection *conn)
  67{
  68        int ret = 0;
  69
  70        if (!mutex_trylock(&conn->c_send_lock))
  71                ret = 1;
  72        else
  73                mutex_unlock(&conn->c_send_lock);
  74
  75        return ret;
  76}
  77
  78static struct rds_connection *rds_conn_lookup(struct hlist_head *head,
  79                                              __be32 laddr, __be32 faddr,
  80                                              struct rds_transport *trans)
  81{
  82        struct rds_connection *conn, *ret = NULL;
  83        struct hlist_node *pos;
  84
  85        hlist_for_each_entry(conn, pos, head, c_hash_node) {
  86                if (conn->c_faddr == faddr && conn->c_laddr == laddr &&
  87                                conn->c_trans == trans) {
  88                        ret = conn;
  89                        break;
  90                }
  91        }
  92        rdsdebug("returning conn %p for %pI4 -> %pI4\n", ret,
  93                 &laddr, &faddr);
  94        return ret;
  95}
  96
  97/*
  98 * This is called by transports as they're bringing down a connection.
  99 * It clears partial message state so that the transport can start sending
 100 * and receiving over this connection again in the future.  It is up to
 101 * the transport to have serialized this call with its send and recv.
 102 */
 103void rds_conn_reset(struct rds_connection *conn)
 104{
 105        rdsdebug("connection %pI4 to %pI4 reset\n",
 106          &conn->c_laddr, &conn->c_faddr);
 107
 108        rds_stats_inc(s_conn_reset);
 109        rds_send_reset(conn);
 110        conn->c_flags = 0;
 111
 112        /* Do not clear next_rx_seq here, else we cannot distinguish
 113         * retransmitted packets from new packets, and will hand all
 114         * of them to the application. That is not consistent with the
 115         * reliability guarantees of RDS. */
 116}
 117
 118/*
 119 * There is only every one 'conn' for a given pair of addresses in the
 120 * system at a time.  They contain messages to be retransmitted and so
 121 * span the lifetime of the actual underlying transport connections.
 122 *
 123 * For now they are not garbage collected once they're created.  They
 124 * are torn down as the module is removed, if ever.
 125 */
 126static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr,
 127                                       struct rds_transport *trans, gfp_t gfp,
 128                                       int is_outgoing)
 129{
 130        struct rds_connection *conn, *parent = NULL;
 131        struct hlist_head *head = rds_conn_bucket(laddr, faddr);
 132        unsigned long flags;
 133        int ret;
 134
 135        spin_lock_irqsave(&rds_conn_lock, flags);
 136        conn = rds_conn_lookup(head, laddr, faddr, trans);
 137        if (conn && conn->c_loopback && conn->c_trans != &rds_loop_transport &&
 138            !is_outgoing) {
 139                /* This is a looped back IB connection, and we're
 140                 * called by the code handling the incoming connect.
 141                 * We need a second connection object into which we
 142                 * can stick the other QP. */
 143                parent = conn;
 144                conn = parent->c_passive;
 145        }
 146        spin_unlock_irqrestore(&rds_conn_lock, flags);
 147        if (conn)
 148                goto out;
 149
 150        conn = kmem_cache_zalloc(rds_conn_slab, gfp);
 151        if (conn == NULL) {
 152                conn = ERR_PTR(-ENOMEM);
 153                goto out;
 154        }
 155
 156        INIT_HLIST_NODE(&conn->c_hash_node);
 157        conn->c_laddr = laddr;
 158        conn->c_faddr = faddr;
 159        spin_lock_init(&conn->c_lock);
 160        conn->c_next_tx_seq = 1;
 161
 162        mutex_init(&conn->c_send_lock);
 163        INIT_LIST_HEAD(&conn->c_send_queue);
 164        INIT_LIST_HEAD(&conn->c_retrans);
 165
 166        ret = rds_cong_get_maps(conn);
 167        if (ret) {
 168                kmem_cache_free(rds_conn_slab, conn);
 169                conn = ERR_PTR(ret);
 170                goto out;
 171        }
 172
 173        /*
 174         * This is where a connection becomes loopback.  If *any* RDS sockets
 175         * can bind to the destination address then we'd rather the messages
 176         * flow through loopback rather than either transport.
 177         */
 178        if (rds_trans_get_preferred(faddr)) {
 179                conn->c_loopback = 1;
 180                if (is_outgoing && trans->t_prefer_loopback) {
 181                        /* "outgoing" connection - and the transport
 182                         * says it wants the connection handled by the
 183                         * loopback transport. This is what TCP does.
 184                         */
 185                        trans = &rds_loop_transport;
 186                }
 187        }
 188
 189        conn->c_trans = trans;
 190
 191        ret = trans->conn_alloc(conn, gfp);
 192        if (ret) {
 193                kmem_cache_free(rds_conn_slab, conn);
 194                conn = ERR_PTR(ret);
 195                goto out;
 196        }
 197
 198        atomic_set(&conn->c_state, RDS_CONN_DOWN);
 199        conn->c_reconnect_jiffies = 0;
 200        INIT_DELAYED_WORK(&conn->c_send_w, rds_send_worker);
 201        INIT_DELAYED_WORK(&conn->c_recv_w, rds_recv_worker);
 202        INIT_DELAYED_WORK(&conn->c_conn_w, rds_connect_worker);
 203        INIT_WORK(&conn->c_down_w, rds_shutdown_worker);
 204        mutex_init(&conn->c_cm_lock);
 205        conn->c_flags = 0;
 206
 207        rdsdebug("allocated conn %p for %pI4 -> %pI4 over %s %s\n",
 208          conn, &laddr, &faddr,
 209          trans->t_name ? trans->t_name : "[unknown]",
 210          is_outgoing ? "(outgoing)" : "");
 211
 212        /*
 213         * Since we ran without holding the conn lock, someone could
 214         * have created the same conn (either normal or passive) in the
 215         * interim. We check while holding the lock. If we won, we complete
 216         * init and return our conn. If we lost, we rollback and return the
 217         * other one.
 218         */
 219        spin_lock_irqsave(&rds_conn_lock, flags);
 220        if (parent) {
 221                /* Creating passive conn */
 222                if (parent->c_passive) {
 223                        trans->conn_free(conn->c_transport_data);
 224                        kmem_cache_free(rds_conn_slab, conn);
 225                        conn = parent->c_passive;
 226                } else {
 227                        parent->c_passive = conn;
 228                        rds_cong_add_conn(conn);
 229                        rds_conn_count++;
 230                }
 231        } else {
 232                /* Creating normal conn */
 233                struct rds_connection *found;
 234
 235                found = rds_conn_lookup(head, laddr, faddr, trans);
 236                if (found) {
 237                        trans->conn_free(conn->c_transport_data);
 238                        kmem_cache_free(rds_conn_slab, conn);
 239                        conn = found;
 240                } else {
 241                        hlist_add_head(&conn->c_hash_node, head);
 242                        rds_cong_add_conn(conn);
 243                        rds_conn_count++;
 244                }
 245        }
 246        spin_unlock_irqrestore(&rds_conn_lock, flags);
 247
 248out:
 249        return conn;
 250}
 251
 252struct rds_connection *rds_conn_create(__be32 laddr, __be32 faddr,
 253                                       struct rds_transport *trans, gfp_t gfp)
 254{
 255        return __rds_conn_create(laddr, faddr, trans, gfp, 0);
 256}
 257EXPORT_SYMBOL_GPL(rds_conn_create);
 258
 259struct rds_connection *rds_conn_create_outgoing(__be32 laddr, __be32 faddr,
 260                                       struct rds_transport *trans, gfp_t gfp)
 261{
 262        return __rds_conn_create(laddr, faddr, trans, gfp, 1);
 263}
 264EXPORT_SYMBOL_GPL(rds_conn_create_outgoing);
 265
 266void rds_conn_destroy(struct rds_connection *conn)
 267{
 268        struct rds_message *rm, *rtmp;
 269
 270        rdsdebug("freeing conn %p for %pI4 -> "
 271                 "%pI4\n", conn, &conn->c_laddr,
 272                 &conn->c_faddr);
 273
 274        hlist_del_init(&conn->c_hash_node);
 275
 276        /* wait for the rds thread to shut it down */
 277        atomic_set(&conn->c_state, RDS_CONN_ERROR);
 278        cancel_delayed_work(&conn->c_conn_w);
 279        queue_work(rds_wq, &conn->c_down_w);
 280        flush_workqueue(rds_wq);
 281
 282        /* tear down queued messages */
 283        list_for_each_entry_safe(rm, rtmp,
 284                                 &conn->c_send_queue,
 285                                 m_conn_item) {
 286                list_del_init(&rm->m_conn_item);
 287                BUG_ON(!list_empty(&rm->m_sock_item));
 288                rds_message_put(rm);
 289        }
 290        if (conn->c_xmit_rm)
 291                rds_message_put(conn->c_xmit_rm);
 292
 293        conn->c_trans->conn_free(conn->c_transport_data);
 294
 295        /*
 296         * The congestion maps aren't freed up here.  They're
 297         * freed by rds_cong_exit() after all the connections
 298         * have been freed.
 299         */
 300        rds_cong_remove_conn(conn);
 301
 302        BUG_ON(!list_empty(&conn->c_retrans));
 303        kmem_cache_free(rds_conn_slab, conn);
 304
 305        rds_conn_count--;
 306}
 307EXPORT_SYMBOL_GPL(rds_conn_destroy);
 308
 309static void rds_conn_message_info(struct socket *sock, unsigned int len,
 310                                  struct rds_info_iterator *iter,
 311                                  struct rds_info_lengths *lens,
 312                                  int want_send)
 313{
 314        struct hlist_head *head;
 315        struct hlist_node *pos;
 316        struct list_head *list;
 317        struct rds_connection *conn;
 318        struct rds_message *rm;
 319        unsigned long flags;
 320        unsigned int total = 0;
 321        size_t i;
 322
 323        len /= sizeof(struct rds_info_message);
 324
 325        spin_lock_irqsave(&rds_conn_lock, flags);
 326
 327        for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 328             i++, head++) {
 329                hlist_for_each_entry(conn, pos, head, c_hash_node) {
 330                        if (want_send)
 331                                list = &conn->c_send_queue;
 332                        else
 333                                list = &conn->c_retrans;
 334
 335                        spin_lock(&conn->c_lock);
 336
 337                        /* XXX too lazy to maintain counts.. */
 338                        list_for_each_entry(rm, list, m_conn_item) {
 339                                total++;
 340                                if (total <= len)
 341                                        rds_inc_info_copy(&rm->m_inc, iter,
 342                                                          conn->c_laddr,
 343                                                          conn->c_faddr, 0);
 344                        }
 345
 346                        spin_unlock(&conn->c_lock);
 347                }
 348        }
 349
 350        spin_unlock_irqrestore(&rds_conn_lock, flags);
 351
 352        lens->nr = total;
 353        lens->each = sizeof(struct rds_info_message);
 354}
 355
 356static void rds_conn_message_info_send(struct socket *sock, unsigned int len,
 357                                       struct rds_info_iterator *iter,
 358                                       struct rds_info_lengths *lens)
 359{
 360        rds_conn_message_info(sock, len, iter, lens, 1);
 361}
 362
 363static void rds_conn_message_info_retrans(struct socket *sock,
 364                                          unsigned int len,
 365                                          struct rds_info_iterator *iter,
 366                                          struct rds_info_lengths *lens)
 367{
 368        rds_conn_message_info(sock, len, iter, lens, 0);
 369}
 370
 371void rds_for_each_conn_info(struct socket *sock, unsigned int len,
 372                          struct rds_info_iterator *iter,
 373                          struct rds_info_lengths *lens,
 374                          int (*visitor)(struct rds_connection *, void *),
 375                          size_t item_len)
 376{
 377        uint64_t buffer[(item_len + 7) / 8];
 378        struct hlist_head *head;
 379        struct hlist_node *pos;
 380        struct hlist_node *tmp;
 381        struct rds_connection *conn;
 382        unsigned long flags;
 383        size_t i;
 384
 385        spin_lock_irqsave(&rds_conn_lock, flags);
 386
 387        lens->nr = 0;
 388        lens->each = item_len;
 389
 390        for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 391             i++, head++) {
 392                hlist_for_each_entry_safe(conn, pos, tmp, head, c_hash_node) {
 393
 394                        /* XXX no c_lock usage.. */
 395                        if (!visitor(conn, buffer))
 396                                continue;
 397
 398                        /* We copy as much as we can fit in the buffer,
 399                         * but we count all items so that the caller
 400                         * can resize the buffer. */
 401                        if (len >= item_len) {
 402                                rds_info_copy(iter, buffer, item_len);
 403                                len -= item_len;
 404                        }
 405                        lens->nr++;
 406                }
 407        }
 408
 409        spin_unlock_irqrestore(&rds_conn_lock, flags);
 410}
 411EXPORT_SYMBOL_GPL(rds_for_each_conn_info);
 412
 413static int rds_conn_info_visitor(struct rds_connection *conn,
 414                                  void *buffer)
 415{
 416        struct rds_info_connection *cinfo = buffer;
 417
 418        cinfo->next_tx_seq = conn->c_next_tx_seq;
 419        cinfo->next_rx_seq = conn->c_next_rx_seq;
 420        cinfo->laddr = conn->c_laddr;
 421        cinfo->faddr = conn->c_faddr;
 422        strncpy(cinfo->transport, conn->c_trans->t_name,
 423                sizeof(cinfo->transport));
 424        cinfo->flags = 0;
 425
 426        rds_conn_info_set(cinfo->flags,
 427                          rds_conn_is_sending(conn), SENDING);
 428        /* XXX Future: return the state rather than these funky bits */
 429        rds_conn_info_set(cinfo->flags,
 430                          atomic_read(&conn->c_state) == RDS_CONN_CONNECTING,
 431                          CONNECTING);
 432        rds_conn_info_set(cinfo->flags,
 433                          atomic_read(&conn->c_state) == RDS_CONN_UP,
 434                          CONNECTED);
 435        return 1;
 436}
 437
 438static void rds_conn_info(struct socket *sock, unsigned int len,
 439                          struct rds_info_iterator *iter,
 440                          struct rds_info_lengths *lens)
 441{
 442        rds_for_each_conn_info(sock, len, iter, lens,
 443                                rds_conn_info_visitor,
 444                                sizeof(struct rds_info_connection));
 445}
 446
 447int __init rds_conn_init(void)
 448{
 449        rds_conn_slab = kmem_cache_create("rds_connection",
 450                                          sizeof(struct rds_connection),
 451                                          0, 0, NULL);
 452        if (rds_conn_slab == NULL)
 453                return -ENOMEM;
 454
 455        rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 456        rds_info_register_func(RDS_INFO_SEND_MESSAGES,
 457                               rds_conn_message_info_send);
 458        rds_info_register_func(RDS_INFO_RETRANS_MESSAGES,
 459                               rds_conn_message_info_retrans);
 460
 461        return 0;
 462}
 463
 464void rds_conn_exit(void)
 465{
 466        rds_loop_exit();
 467
 468        WARN_ON(!hlist_empty(rds_conn_hash));
 469
 470        kmem_cache_destroy(rds_conn_slab);
 471
 472        rds_info_deregister_func(RDS_INFO_CONNECTIONS, rds_conn_info);
 473        rds_info_deregister_func(RDS_INFO_SEND_MESSAGES,
 474                                 rds_conn_message_info_send);
 475        rds_info_deregister_func(RDS_INFO_RETRANS_MESSAGES,
 476                                 rds_conn_message_info_retrans);
 477}
 478
 479/*
 480 * Force a disconnect
 481 */
 482void rds_conn_drop(struct rds_connection *conn)
 483{
 484        atomic_set(&conn->c_state, RDS_CONN_ERROR);
 485        queue_work(rds_wq, &conn->c_down_w);
 486}
 487EXPORT_SYMBOL_GPL(rds_conn_drop);
 488
 489/*
 490 * An error occurred on the connection
 491 */
 492void
 493__rds_conn_error(struct rds_connection *conn, const char *fmt, ...)
 494{
 495        va_list ap;
 496
 497        va_start(ap, fmt);
 498        vprintk(fmt, ap);
 499        va_end(ap);
 500
 501        rds_conn_drop(conn);
 502}
 503