net/rds/send.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 <net/sock.h>
  35 #include <linux/in.h>
  36 #include <linux/list.h>
  37
  38 #include "rds.h"
  39 #include "rdma.h"
  40
  41 /* When transmitting messages in rds_send_xmit, we need to emerge from
  42  * time to time and briefly release the CPU. Otherwise the softlock watchdog
  43  * will kick our shin.
  44  * Also, it seems fairer to not let one busy connection stall all the
  45  * others.
  46  *
  47  * send_batch_count is the number of times we'll loop in send_xmit. Setting
  48  * it to 0 will restore the old behavior (where we looped until we had
  49  * drained the queue).
  50  */
  51 static int send_batch_count = 64;
  52 module_param(send_batch_count, int, 0444);
  53 MODULE_PARM_DESC(send_batch_count, " batch factor when working the send queue");
  54
  55 /*
  56  * Reset the send state. Caller must hold c_send_lock when calling here.
  57  */
  58 void rds_send_reset(struct rds_connection *conn)
  59 {
  60         struct rds_message *rm, *tmp;
  61         unsigned long flags;
  62
  63         if (conn->c_xmit_rm) {
  64                 /* Tell the user the RDMA op is no longer mapped by the
  65                  * transport. This isn't entirely true (it's flushed out
  66                  * independently) but as the connection is down, there's
  67                  * no ongoing RDMA to/from that memory */
  68                 rds_message_unmapped(conn->c_xmit_rm);
  69                 rds_message_put(conn->c_xmit_rm);
  70                 conn->c_xmit_rm = NULL;
  71         }
  72         conn->c_xmit_sg = 0;
  73         conn->c_xmit_hdr_off = 0;
  74         conn->c_xmit_data_off = 0;
  75         conn->c_xmit_rdma_sent = 0;
  76
  77         conn->c_map_queued = 0;
  78
  79         conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
  80         conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
  81
  82         /* Mark messages as retransmissions, and move them to the send q */
  83         spin_lock_irqsave(&conn->c_lock, flags);
  84         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
  85                 set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
  86                 set_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags);
  87         }
  88         list_splice_init(&conn->c_retrans, &conn->c_send_queue);
  89         spin_unlock_irqrestore(&conn->c_lock, flags);
  90 }
  91
  92 /*
  93  * We're making the concious trade-off here to only send one message
  94  * down the connection at a time.
  95  *   Pro:
  96  *      - tx queueing is a simple fifo list
  97  *      - reassembly is optional and easily done by transports per conn
  98  *      - no per flow rx lookup at all, straight to the socket
  99  *      - less per-frag memory and wire overhead
 100  *   Con:
 101  *      - queued acks can be delayed behind large messages
 102  *   Depends:
 103  *      - small message latency is higher behind queued large messages
 104  *      - large message latency isn't starved by intervening small sends
 105  */
 106 int rds_send_xmit(struct rds_connection *conn)
 107 {
 108         struct rds_message *rm;
 109         unsigned long flags;
 110         unsigned int tmp;
 111         unsigned int send_quota = send_batch_count;
 112         struct scatterlist *sg;
 113         int ret = 0;
 114         int was_empty = 0;
 115         LIST_HEAD(to_be_dropped);
 116
 117         /*
 118          * sendmsg calls here after having queued its message on the send
 119          * queue.  We only have one task feeding the connection at a time.  If
 120          * another thread is already feeding the queue then we back off.  This
 121          * avoids blocking the caller and trading per-connection data between
 122          * caches per message.
 123          *
 124          * The sem holder will issue a retry if they notice that someone queued
 125          * a message after they stopped walking the send queue but before they
 126          * dropped the sem.
 127          */
 128         if (!mutex_trylock(&conn->c_send_lock)) {
 129                 rds_stats_inc(s_send_sem_contention);
 130                 ret = -ENOMEM;
 131                 goto out;
 132         }
 133
 134         if (conn->c_trans->xmit_prepare)
 135                 conn->c_trans->xmit_prepare(conn);
 136
 137         /*
 138          * spin trying to push headers and data down the connection until
 139          * the connection doens't make forward progress.
 140          */
 141         while (--send_quota) {
 142                 /*
 143                  * See if need to send a congestion map update if we're
 144                  * between sending messages.  The send_sem protects our sole
 145                  * use of c_map_offset and _bytes.
 146                  * Note this is used only by transports that define a special
 147                  * xmit_cong_map function. For all others, we create allocate
 148                  * a cong_map message and treat it just like any other send.
 149                  */
 150                 if (conn->c_map_bytes) {
 151                         ret = conn->c_trans->xmit_cong_map(conn, conn->c_lcong,
 152                                                 conn->c_map_offset);
 153                         if (ret <= 0)
 154                                 break;
 155
 156                         conn->c_map_offset += ret;
 157                         conn->c_map_bytes -= ret;
 158                         if (conn->c_map_bytes)
 159                                 continue;
 160                 }
 161
 162                 /* If we're done sending the current message, clear the
 163                  * offset and S/G temporaries.
 164                  */
 165                 rm = conn->c_xmit_rm;
 166                 if (rm != NULL &&
 167                     conn->c_xmit_hdr_off == sizeof(struct rds_header) &&
 168                     conn->c_xmit_sg == rm->m_nents) {
 169                         conn->c_xmit_rm = NULL;
 170                         conn->c_xmit_sg = 0;
 171                         conn->c_xmit_hdr_off = 0;
 172                         conn->c_xmit_data_off = 0;
 173                         conn->c_xmit_rdma_sent = 0;
 174
 175                         /* Release the reference to the previous message. */
 176                         rds_message_put(rm);
 177                         rm = NULL;
 178                 }
 179
 180                 /* If we're asked to send a cong map update, do so.
 181                  */
 182                 if (rm == NULL && test_and_clear_bit(0, &conn->c_map_queued)) {
 183                         if (conn->c_trans->xmit_cong_map != NULL) {
 184                                 conn->c_map_offset = 0;
 185                                 conn->c_map_bytes = sizeof(struct rds_header) +
 186                                         RDS_CONG_MAP_BYTES;
 187                                 continue;
 188                         }
 189
 190                         rm = rds_cong_update_alloc(conn);
 191                         if (IS_ERR(rm)) {
 192                                 ret = PTR_ERR(rm);
 193                                 break;
 194                         }
 195
 196                         conn->c_xmit_rm = rm;
 197                 }
 198
 199                 /*
 200                  * Grab the next message from the send queue, if there is one.
 201                  *
 202                  * c_xmit_rm holds a ref while we're sending this message down
 203                  * the connction.  We can use this ref while holding the
 204                  * send_sem.. rds_send_reset() is serialized with it.
 205                  */
 206                 if (rm == NULL) {
 207                         unsigned int len;
 208
 209                         spin_lock_irqsave(&conn->c_lock, flags);
 210
 211                         if (!list_empty(&conn->c_send_queue)) {
 212                                 rm = list_entry(conn->c_send_queue.next,
 213                                                 struct rds_message,
 214                                                 m_conn_item);
 215                                 rds_message_addref(rm);
 216
 217                                 /*
 218                                  * Move the message from the send queue to the retransmit
 219                                  * list right away.
 220                                  */
 221                                 list_move_tail(&rm->m_conn_item, &conn->c_retrans);
 222                         }
 223
 224                         spin_unlock_irqrestore(&conn->c_lock, flags);
 225
 226                         if (rm == NULL) {
 227                                 was_empty = 1;
 228                                 break;
 229                         }
 230
 231                         /* Unfortunately, the way Infiniband deals with
 232                          * RDMA to a bad MR key is by moving the entire
 233                          * queue pair to error state. We cold possibly
 234                          * recover from that, but right now we drop the
 235                          * connection.
 236                          * Therefore, we never retransmit messages with RDMA ops.
 237                          */
 238                         if (rm->m_rdma_op
 239                          && test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags)) {
 240                                 spin_lock_irqsave(&conn->c_lock, flags);
 241                                 if (test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags))
 242                                         list_move(&rm->m_conn_item, &to_be_dropped);
 243                                 spin_unlock_irqrestore(&conn->c_lock, flags);
 244                                 rds_message_put(rm);
 245                                 continue;
 246                         }
 247
 248                         /* Require an ACK every once in a while */
 249                         len = ntohl(rm->m_inc.i_hdr.h_len);
 250                         if (conn->c_unacked_packets == 0
 251                          || conn->c_unacked_bytes < len) {
 252                                 __set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
 253
 254                                 conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
 255                                 conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
 256                                 rds_stats_inc(s_send_ack_required);
 257                         } else {
 258                                 conn->c_unacked_bytes -= len;
 259                                 conn->c_unacked_packets--;
 260                         }
 261
 262                         conn->c_xmit_rm = rm;
 263                 }
 264
 265                 /*
 266                  * Try and send an rdma message.  Let's see if we can
 267                  * keep this simple and require that the transport either
 268                  * send the whole rdma or none of it.
 269                  */
 270                 if (rm->m_rdma_op && !conn->c_xmit_rdma_sent) {
 271                         ret = conn->c_trans->xmit_rdma(conn, rm->m_rdma_op);
 272                         if (ret)
 273                                 break;
 274                         conn->c_xmit_rdma_sent = 1;
 275                         /* The transport owns the mapped memory for now.
 276                          * You can't unmap it while it's on the send queue */
 277                         set_bit(RDS_MSG_MAPPED, &rm->m_flags);
 278                 }
 279
 280                 if (conn->c_xmit_hdr_off < sizeof(struct rds_header) ||
 281                     conn->c_xmit_sg < rm->m_nents) {
 282                         ret = conn->c_trans->xmit(conn, rm,
 283                                                   conn->c_xmit_hdr_off,
 284                                                   conn->c_xmit_sg,
 285                                                   conn->c_xmit_data_off);
 286                         if (ret <= 0)
 287                                 break;
 288
 289                         if (conn->c_xmit_hdr_off < sizeof(struct rds_header)) {
 290                                 tmp = min_t(int, ret,
 291                                             sizeof(struct rds_header) -
 292                                             conn->c_xmit_hdr_off);
 293                                 conn->c_xmit_hdr_off += tmp;
 294                                 ret -= tmp;
 295                         }
 296
 297                         sg = &rm->m_sg[conn->c_xmit_sg];
 298                         while (ret) {
 299                                 tmp = min_t(int, ret, sg->length -
 300                                                       conn->c_xmit_data_off);
 301                                 conn->c_xmit_data_off += tmp;
 302                                 ret -= tmp;
 303                                 if (conn->c_xmit_data_off == sg->length) {
 304                                         conn->c_xmit_data_off = 0;
 305                                         sg++;
 306                                         conn->c_xmit_sg++;
 307                                         BUG_ON(ret != 0 &&
 308                                                conn->c_xmit_sg == rm->m_nents);
 309                                 }
 310                         }
 311                 }
 312         }
 313
 314         /* Nuke any messages we decided not to retransmit. */
 315         if (!list_empty(&to_be_dropped))
 316                 rds_send_remove_from_sock(&to_be_dropped, RDS_RDMA_DROPPED);
 317
 318         if (conn->c_trans->xmit_complete)
 319                 conn->c_trans->xmit_complete(conn);
 320
 321         /*
 322          * We might be racing with another sender who queued a message but
 323          * backed off on noticing that we held the c_send_lock.  If we check
 324          * for queued messages after dropping the sem then either we'll
 325          * see the queued message or the queuer will get the sem.  If we
 326          * notice the queued message then we trigger an immediate retry.
 327          *
 328          * We need to be careful only to do this when we stopped processing
 329          * the send queue because it was empty.  It's the only way we
 330          * stop processing the loop when the transport hasn't taken
 331          * responsibility for forward progress.
 332          */
 333         mutex_unlock(&conn->c_send_lock);
 334
 335         if (conn->c_map_bytes || (send_quota == 0 && !was_empty)) {
 336                 /* We exhausted the send quota, but there's work left to
 337                  * do. Return and (re-)schedule the send worker.
 338                  */
 339                 ret = -EAGAIN;
 340         }
 341
 342         if (ret == 0 && was_empty) {
 343                 /* A simple bit test would be way faster than taking the
 344                  * spin lock */
 345                 spin_lock_irqsave(&conn->c_lock, flags);
 346                 if (!list_empty(&conn->c_send_queue)) {
 347                         rds_stats_inc(s_send_sem_queue_raced);
 348                         ret = -EAGAIN;
 349                 }
 350                 spin_unlock_irqrestore(&conn->c_lock, flags);
 351         }
 352 out:
 353         return ret;
 354 }
 355
 356 static void rds_send_sndbuf_remove(struct rds_sock *rs, struct rds_message *rm)
 357 {
 358         u32 len = be32_to_cpu(rm->m_inc.i_hdr.h_len);
 359
 360         assert_spin_locked(&rs->rs_lock);
 361
 362         BUG_ON(rs->rs_snd_bytes < len);
 363         rs->rs_snd_bytes -= len;
 364
 365         if (rs->rs_snd_bytes == 0)
 366                 rds_stats_inc(s_send_queue_empty);
 367 }
 368
 369 static inline int rds_send_is_acked(struct rds_message *rm, u64 ack,
 370                                     is_acked_func is_acked)
 371 {
 372         if (is_acked)
 373                 return is_acked(rm, ack);
 374         return be64_to_cpu(rm->m_inc.i_hdr.h_sequence) <= ack;
 375 }
 376
 377 /*
 378  * Returns true if there are no messages on the send and retransmit queues
 379  * which have a sequence number greater than or equal to the given sequence
 380  * number.
 381  */
 382 int rds_send_acked_before(struct rds_connection *conn, u64 seq)
 383 {
 384         struct rds_message *rm, *tmp;
 385         int ret = 1;
 386
 387         spin_lock(&conn->c_lock);
 388
 389         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
 390                 if (be64_to_cpu(rm->m_inc.i_hdr.h_sequence) < seq)
 391                         ret = 0;
 392                 break;
 393         }
 394
 395         list_for_each_entry_safe(rm, tmp, &conn->c_send_queue, m_conn_item) {
 396                 if (be64_to_cpu(rm->m_inc.i_hdr.h_sequence) < seq)
 397                         ret = 0;
 398                 break;
 399         }
 400
 401         spin_unlock(&conn->c_lock);
 402
 403         return ret;
 404 }
 405
 406 /*
 407  * This is pretty similar to what happens below in the ACK
 408  * handling code - except that we call here as soon as we get
 409  * the IB send completion on the RDMA op and the accompanying
 410  * message.
 411  */
 412 void rds_rdma_send_complete(struct rds_message *rm, int status)
 413 {
 414         struct rds_sock *rs = NULL;
 415         struct rds_rdma_op *ro;
 416         struct rds_notifier *notifier;
 417
 418         spin_lock(&rm->m_rs_lock);
 419
 420         ro = rm->m_rdma_op;
 421         if (test_bit(RDS_MSG_ON_SOCK, &rm->m_flags)
 422          && ro && ro->r_notify && ro->r_notifier) {
 423                 notifier = ro->r_notifier;
 424                 rs = rm->m_rs;
 425                 sock_hold(rds_rs_to_sk(rs));
 426
 427                 notifier->n_status = status;
 428                 spin_lock(&rs->rs_lock);
 429                 list_add_tail(&notifier->n_list, &rs->rs_notify_queue);
 430                 spin_unlock(&rs->rs_lock);
 431
 432                 ro->r_notifier = NULL;
 433         }
 434
 435         spin_unlock(&rm->m_rs_lock);
 436
 437         if (rs) {
 438                 rds_wake_sk_sleep(rs);
 439                 sock_put(rds_rs_to_sk(rs));
 440         }
 441 }
 442
 443 /*
 444  * This is the same as rds_rdma_send_complete except we
 445  * don't do any locking - we have all the ingredients (message,
 446  * socket, socket lock) and can just move the notifier.
 447  */
 448 static inline void
 449 __rds_rdma_send_complete(struct rds_sock *rs, struct rds_message *rm, int status)
 450 {
 451         struct rds_rdma_op *ro;
 452
 453         ro = rm->m_rdma_op;
 454         if (ro && ro->r_notify && ro->r_notifier) {
 455                 ro->r_notifier->n_status = status;
 456                 list_add_tail(&ro->r_notifier->n_list, &rs->rs_notify_queue);
 457                 ro->r_notifier = NULL;
 458         }
 459
 460         /* No need to wake the app - caller does this */
 461 }
 462
 463 /*
 464  * This is called from the IB send completion when we detect
 465  * a RDMA operation that failed with remote access error.
 466  * So speed is not an issue here.
 467  */
 468 struct rds_message *rds_send_get_message(struct rds_connection *conn,
 469                                          struct rds_rdma_op *op)
 470 {
 471         struct rds_message *rm, *tmp, *found = NULL;
 472         unsigned long flags;
 473
 474         spin_lock_irqsave(&conn->c_lock, flags);
 475
 476         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
 477                 if (rm->m_rdma_op == op) {
 478                         atomic_inc(&rm->m_refcount);
 479                         found = rm;
 480                         goto out;
 481                 }
 482         }
 483
 484         list_for_each_entry_safe(rm, tmp, &conn->c_send_queue, m_conn_item) {
 485                 if (rm->m_rdma_op == op) {
 486                         atomic_inc(&rm->m_refcount);
 487                         found = rm;
 488                         break;
 489                 }
 490         }
 491
 492 out:
 493         spin_unlock_irqrestore(&conn->c_lock, flags);
 494
 495         return found;
 496 }
 497
 498 /*
 499  * This removes messages from the socket's list if they're on it.  The list
 500  * argument must be private to the caller, we must be able to modify it
 501  * without locks.  The messages must have a reference held for their
 502  * position on the list.  This function will drop that reference after
 503  * removing the messages from the 'messages' list regardless of if it found
 504  * the messages on the socket list or not.
 505  */
 506 void rds_send_remove_from_sock(struct list_head *messages, int status)
 507 {
 508         unsigned long flags = 0; /* silence gcc :P */
 509         struct rds_sock *rs = NULL;
 510         struct rds_message *rm;
 511
 512         local_irq_save(flags);
 513         while (!list_empty(messages)) {
 514                 rm = list_entry(messages->next, struct rds_message,
 515                                 m_conn_item);
 516                 list_del_init(&rm->m_conn_item);
 517
 518                 /*
 519                  * If we see this flag cleared then we're *sure* that someone
 520                  * else beat us to removing it from the sock.  If we race
 521                  * with their flag update we'll get the lock and then really
 522                  * see that the flag has been cleared.
 523                  *
 524                  * The message spinlock makes sure nobody clears rm->m_rs
 525                  * while we're messing with it. It does not prevent the
 526                  * message from being removed from the socket, though.
 527                  */
 528                 spin_lock(&rm->m_rs_lock);
 529                 if (!test_bit(RDS_MSG_ON_SOCK, &rm->m_flags))
 530                         goto unlock_and_drop;
 531
 532                 if (rs != rm->m_rs) {
 533                         if (rs) {
 534                                 spin_unlock(&rs->rs_lock);
 535                                 rds_wake_sk_sleep(rs);
 536                                 sock_put(rds_rs_to_sk(rs));
 537                         }
 538                         rs = rm->m_rs;
 539                         spin_lock(&rs->rs_lock);
 540                         sock_hold(rds_rs_to_sk(rs));
 541                 }
 542
 543                 if (test_and_clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags)) {
 544                         struct rds_rdma_op *ro = rm->m_rdma_op;
 545                         struct rds_notifier *notifier;
 546
 547                         list_del_init(&rm->m_sock_item);
 548                         rds_send_sndbuf_remove(rs, rm);
 549
 550                         if (ro && ro->r_notifier
 551                            && (status || ro->r_notify)) {
 552                                 notifier = ro->r_notifier;
 553                                 list_add_tail(&notifier->n_list,
 554                                                 &rs->rs_notify_queue);
 555                                 if (!notifier->n_status)
 556                                         notifier->n_status = status;
 557                                 rm->m_rdma_op->r_notifier = NULL;
 558                         }
 559                         rds_message_put(rm);
 560                         rm->m_rs = NULL;
 561                 }
 562
 563 unlock_and_drop:
 564                 spin_unlock(&rm->m_rs_lock);
 565                 rds_message_put(rm);
 566         }
 567
 568         if (rs) {
 569                 spin_unlock(&rs->rs_lock);
 570                 rds_wake_sk_sleep(rs);
 571                 sock_put(rds_rs_to_sk(rs));
 572         }
 573         local_irq_restore(flags);
 574 }
 575
 576 /*
 577  * Transports call here when they've determined that the receiver queued
 578  * messages up to, and including, the given sequence number.  Messages are
 579  * moved to the retrans queue when rds_send_xmit picks them off the send
 580  * queue. This means that in the TCP case, the message may not have been
 581  * assigned the m_ack_seq yet - but that's fine as long as tcp_is_acked
 582  * checks the RDS_MSG_HAS_ACK_SEQ bit.
 583  *
 584  * XXX It's not clear to me how this is safely serialized with socket
 585  * destruction.  Maybe it should bail if it sees SOCK_DEAD.
 586  */
 587 void rds_send_drop_acked(struct rds_connection *conn, u64 ack,
 588                          is_acked_func is_acked)
 589 {
 590         struct rds_message *rm, *tmp;
 591         unsigned long flags;
 592         LIST_HEAD(list);
 593
 594         spin_lock_irqsave(&conn->c_lock, flags);
 595
 596         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
 597                 if (!rds_send_is_acked(rm, ack, is_acked))
 598                         break;
 599
 600                 list_move(&rm->m_conn_item, &list);
 601                 clear_bit(RDS_MSG_ON_CONN, &rm->m_flags);
 602         }
 603
 604         /* order flag updates with spin locks */
 605         if (!list_empty(&list))
 606                 smp_mb__after_clear_bit();
 607
 608         spin_unlock_irqrestore(&conn->c_lock, flags);
 609
 610         /* now remove the messages from the sock list as needed */
 611         rds_send_remove_from_sock(&list, RDS_RDMA_SUCCESS);
 612 }
 613
 614 void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest)
 615 {
 616         struct rds_message *rm, *tmp;
 617         struct rds_connection *conn;
 618         unsigned long flags, flags2;
 619         LIST_HEAD(list);
 620         int wake = 0;
 621
 622         /* get all the messages we're dropping under the rs lock */
 623         spin_lock_irqsave(&rs->rs_lock, flags);
 624
 625         list_for_each_entry_safe(rm, tmp, &rs->rs_send_queue, m_sock_item) {
 626                 if (dest && (dest->sin_addr.s_addr != rm->m_daddr ||
 627                              dest->sin_port != rm->m_inc.i_hdr.h_dport))
 628                         continue;
 629
 630                 wake = 1;
 631                 list_move(&rm->m_sock_item, &list);
 632                 rds_send_sndbuf_remove(rs, rm);
 633                 clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags);
 634
 635                 /* If this is a RDMA operation, notify the app. */
 636                 __rds_rdma_send_complete(rs, rm, RDS_RDMA_CANCELED);
 637         }
 638
 639         /* order flag updates with the rs lock */
 640         if (wake)
 641                 smp_mb__after_clear_bit();
 642
 643         spin_unlock_irqrestore(&rs->rs_lock, flags);
 644
 645         if (wake)
 646                 rds_wake_sk_sleep(rs);
 647
 648         conn = NULL;
 649
 650         /* now remove the messages from the conn list as needed */
 651         list_for_each_entry(rm, &list, m_sock_item) {
 652                 /* We do this here rather than in the loop above, so that
 653                  * we don't have to nest m_rs_lock under rs->rs_lock */
 654                 spin_lock_irqsave(&rm->m_rs_lock, flags2);
 655                 rm->m_rs = NULL;
 656                 spin_unlock_irqrestore(&rm->m_rs_lock, flags2);
 657
 658                 /*
 659                  * If we see this flag cleared then we're *sure* that someone
 660                  * else beat us to removing it from the conn.  If we race
 661                  * with their flag update we'll get the lock and then really
 662                  * see that the flag has been cleared.
 663                  */
 664                 if (!test_bit(RDS_MSG_ON_CONN, &rm->m_flags))
 665                         continue;
 666
 667                 if (conn != rm->m_inc.i_conn) {
 668                         if (conn)
 669                                 spin_unlock_irqrestore(&conn->c_lock, flags);
 670                         conn = rm->m_inc.i_conn;
 671                         spin_lock_irqsave(&conn->c_lock, flags);
 672                 }
 673
 674                 if (test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags)) {
 675                         list_del_init(&rm->m_conn_item);
 676                         rds_message_put(rm);
 677                 }
 678         }
 679
 680         if (conn)
 681                 spin_unlock_irqrestore(&conn->c_lock, flags);
 682
 683         while (!list_empty(&list)) {
 684                 rm = list_entry(list.next, struct rds_message, m_sock_item);
 685                 list_del_init(&rm->m_sock_item);
 686
 687                 rds_message_wait(rm);
 688                 rds_message_put(rm);
 689         }
 690 }
 691
 692 /*
 693  * we only want this to fire once so we use the callers 'queued'.  It's
 694  * possible that another thread can race with us and remove the
 695  * message from the flow with RDS_CANCEL_SENT_TO.
 696  */
 697 static int rds_send_queue_rm(struct rds_sock *rs, struct rds_connection *conn,
 698                              struct rds_message *rm, __be16 sport,
 699                              __be16 dport, int *queued)
 700 {
 701         unsigned long flags;
 702         u32 len;
 703
 704         if (*queued)
 705                 goto out;
 706
 707         len = be32_to_cpu(rm->m_inc.i_hdr.h_len);
 708
 709         /* this is the only place which holds both the socket's rs_lock
 710          * and the connection's c_lock */
 711         spin_lock_irqsave(&rs->rs_lock, flags);
 712
 713         /*
 714          * If there is a little space in sndbuf, we don't queue anything,
 715          * and userspace gets -EAGAIN. But poll() indicates there's send
 716          * room. This can lead to bad behavior (spinning) if snd_bytes isn't
 717          * freed up by incoming acks. So we check the *old* value of
 718          * rs_snd_bytes here to allow the last msg to exceed the buffer,
 719          * and poll() now knows no more data can be sent.
 720          */
 721         if (rs->rs_snd_bytes < rds_sk_sndbuf(rs)) {
 722                 rs->rs_snd_bytes += len;
 723
 724                 /* let recv side know we are close to send space exhaustion.
 725                  * This is probably not the optimal way to do it, as this
 726                  * means we set the flag on *all* messages as soon as our
 727                  * throughput hits a certain threshold.
 728                  */
 729                 if (rs->rs_snd_bytes >= rds_sk_sndbuf(rs) / 2)
 730                         __set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
 731
 732                 list_add_tail(&rm->m_sock_item, &rs->rs_send_queue);
 733                 set_bit(RDS_MSG_ON_SOCK, &rm->m_flags);
 734                 rds_message_addref(rm);
 735                 rm->m_rs = rs;
 736
 737                 /* The code ordering is a little weird, but we're
 738                    trying to minimize the time we hold c_lock */
 739                 rds_message_populate_header(&rm->m_inc.i_hdr, sport, dport, 0);
 740                 rm->m_inc.i_conn = conn;
 741                 rds_message_addref(rm);
 742
 743                 spin_lock(&conn->c_lock);
 744                 rm->m_inc.i_hdr.h_sequence = cpu_to_be64(conn->c_next_tx_seq++);
 745                 list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
 746                 set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
 747                 spin_unlock(&conn->c_lock);
 748
 749                 rdsdebug("queued msg %p len %d, rs %p bytes %d seq %llu\n",
 750                          rm, len, rs, rs->rs_snd_bytes,
 751                          (unsigned long long)be64_to_cpu(rm->m_inc.i_hdr.h_sequence));
 752
 753                 *queued = 1;
 754         }
 755
 756         spin_unlock_irqrestore(&rs->rs_lock, flags);
 757 out:
 758         return *queued;
 759 }
 760
 761 static int rds_cmsg_send(struct rds_sock *rs, struct rds_message *rm,
 762                          struct msghdr *msg, int *allocated_mr)
 763 {
 764         struct cmsghdr *cmsg;
 765         int ret = 0;
 766
 767         for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
 768                 if (!CMSG_OK(msg, cmsg))
 769                         return -EINVAL;
 770
 771                 if (cmsg->cmsg_level != SOL_RDS)
 772                         continue;
 773
 774                 /* As a side effect, RDMA_DEST and RDMA_MAP will set
 775                  * rm->m_rdma_cookie and rm->m_rdma_mr.
 776                  */
 777                 switch (cmsg->cmsg_type) {
 778                 case RDS_CMSG_RDMA_ARGS:
 779                         ret = rds_cmsg_rdma_args(rs, rm, cmsg);
 780                         break;
 781
 782                 case RDS_CMSG_RDMA_DEST:
 783                         ret = rds_cmsg_rdma_dest(rs, rm, cmsg);
 784                         break;
 785
 786                 case RDS_CMSG_RDMA_MAP:
 787                         ret = rds_cmsg_rdma_map(rs, rm, cmsg);
 788                         if (!ret)
 789                                 *allocated_mr = 1;
 790                         break;
 791
 792                 default:
 793                         return -EINVAL;
 794                 }
 795
 796                 if (ret)
 797                         break;
 798         }
 799
 800         return ret;
 801 }
 802
 803 int rds_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
 804                 size_t payload_len)
 805 {
 806         struct sock *sk = sock->sk;
 807         struct rds_sock *rs = rds_sk_to_rs(sk);
 808         struct sockaddr_in *usin = (struct sockaddr_in *)msg->msg_name;
 809         __be32 daddr;
 810         __be16 dport;
 811         struct rds_message *rm = NULL;
 812         struct rds_connection *conn;
 813         int ret = 0;
 814         int queued = 0, allocated_mr = 0;
 815         int nonblock = msg->msg_flags & MSG_DONTWAIT;
 816         long timeo = sock_rcvtimeo(sk, nonblock);
 817
 818         /* Mirror Linux UDP mirror of BSD error message compatibility */
 819         /* XXX: Perhaps MSG_MORE someday */
 820         if (msg->msg_flags & ~(MSG_DONTWAIT | MSG_CMSG_COMPAT)) {
 821                 printk(KERN_INFO "msg_flags 0x%08X\n", msg->msg_flags);
 822                 ret = -EOPNOTSUPP;
 823                 goto out;
 824         }
 825
 826         if (msg->msg_namelen) {
 827                 /* XXX fail non-unicast destination IPs? */
 828                 if (msg->msg_namelen < sizeof(*usin) || usin->sin_family != AF_INET) {
 829                         ret = -EINVAL;
 830                         goto out;
 831                 }
 832                 daddr = usin->sin_addr.s_addr;
 833                 dport = usin->sin_port;
 834         } else {
 835                 /* We only care about consistency with ->connect() */
 836                 lock_sock(sk);
 837                 daddr = rs->rs_conn_addr;
 838                 dport = rs->rs_conn_port;
 839                 release_sock(sk);
 840         }
 841
 842         /* racing with another thread binding seems ok here */
 843         if (daddr == 0 || rs->rs_bound_addr == 0) {
 844                 ret = -ENOTCONN; /* XXX not a great errno */
 845                 goto out;
 846         }
 847
 848         rm = rds_message_copy_from_user(msg->msg_iov, payload_len);
 849         if (IS_ERR(rm)) {
 850                 ret = PTR_ERR(rm);
 851                 rm = NULL;
 852                 goto out;
 853         }
 854
 855         rm->m_daddr = daddr;
 856
 857         /* rds_conn_create has a spinlock that runs with IRQ off.
 858          * Caching the conn in the socket helps a lot. */
 859         if (rs->rs_conn && rs->rs_conn->c_faddr == daddr)
 860                 conn = rs->rs_conn;
 861         else {
 862                 conn = rds_conn_create_outgoing(rs->rs_bound_addr, daddr,
 863                                         rs->rs_transport,
 864                                         sock->sk->sk_allocation);
 865                 if (IS_ERR(conn)) {
 866                         ret = PTR_ERR(conn);
 867                         goto out;
 868                 }
 869                 rs->rs_conn = conn;
 870         }
 871
 872         /* Parse any control messages the user may have included. */
 873         ret = rds_cmsg_send(rs, rm, msg, &allocated_mr);
 874         if (ret)
 875                 goto out;
 876
 877         if ((rm->m_rdma_cookie || rm->m_rdma_op)
 878          && conn->c_trans->xmit_rdma == NULL) {
 879                 if (printk_ratelimit())
 880                         printk(KERN_NOTICE "rdma_op %p conn xmit_rdma %p\n",
 881                                 rm->m_rdma_op, conn->c_trans->xmit_rdma);
 882                 ret = -EOPNOTSUPP;
 883                 goto out;
 884         }
 885
 886         /* If the connection is down, trigger a connect. We may
 887          * have scheduled a delayed reconnect however - in this case
 888          * we should not interfere.
 889          */
 890         if (rds_conn_state(conn) == RDS_CONN_DOWN
 891          && !test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
 892                 queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
 893
 894         ret = rds_cong_wait(conn->c_fcong, dport, nonblock, rs);
 895         if (ret)
 896                 goto out;
 897
 898         while (!rds_send_queue_rm(rs, conn, rm, rs->rs_bound_port,
 899                                   dport, &queued)) {
 900                 rds_stats_inc(s_send_queue_full);
 901                 /* XXX make sure this is reasonable */
 902                 if (payload_len > rds_sk_sndbuf(rs)) {
 903                         ret = -EMSGSIZE;
 904                         goto out;
 905                 }
 906                 if (nonblock) {
 907                         ret = -EAGAIN;
 908                         goto out;
 909                 }
 910
 911                 timeo = wait_event_interruptible_timeout(*sk->sk_sleep,
 912                                         rds_send_queue_rm(rs, conn, rm,
 913                                                           rs->rs_bound_port,
 914                                                           dport,
 915                                                           &queued),
 916                                         timeo);
 917                 rdsdebug("sendmsg woke queued %d timeo %ld\n", queued, timeo);
 918                 if (timeo > 0 || timeo == MAX_SCHEDULE_TIMEOUT)
 919                         continue;
 920
 921                 ret = timeo;
 922                 if (ret == 0)
 923                         ret = -ETIMEDOUT;
 924                 goto out;
 925         }
 926
 927         /*
 928          * By now we've committed to the send.  We reuse rds_send_worker()
 929          * to retry sends in the rds thread if the transport asks us to.
 930          */
 931         rds_stats_inc(s_send_queued);
 932
 933         if (!test_bit(RDS_LL_SEND_FULL, &conn->c_flags))
 934                 rds_send_worker(&conn->c_send_w.work);
 935
 936         rds_message_put(rm);
 937         return payload_len;
 938
 939 out:
 940         /* If the user included a RDMA_MAP cmsg, we allocated a MR on the fly.
 941          * If the sendmsg goes through, we keep the MR. If it fails with EAGAIN
 942          * or in any other way, we need to destroy the MR again */
 943         if (allocated_mr)
 944                 rds_rdma_unuse(rs, rds_rdma_cookie_key(rm->m_rdma_cookie), 1);
 945
 946         if (rm)
 947                 rds_message_put(rm);
 948         return ret;
 949 }
 950
 951 /*
 952  * Reply to a ping packet.
 953  */
 954 int
 955 rds_send_pong(struct rds_connection *conn, __be16 dport)
 956 {
 957         struct rds_message *rm;
 958         unsigned long flags;
 959         int ret = 0;
 960
 961         rm = rds_message_alloc(0, GFP_ATOMIC);
 962         if (rm == NULL) {
 963                 ret = -ENOMEM;
 964                 goto out;
 965         }
 966
 967         rm->m_daddr = conn->c_faddr;
 968
 969         /* If the connection is down, trigger a connect. We may
 970          * have scheduled a delayed reconnect however - in this case
 971          * we should not interfere.
 972          */
 973         if (rds_conn_state(conn) == RDS_CONN_DOWN
 974          && !test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
 975                 queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
 976
 977         ret = rds_cong_wait(conn->c_fcong, dport, 1, NULL);
 978         if (ret)
 979                 goto out;
 980
 981         spin_lock_irqsave(&conn->c_lock, flags);
 982         list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
 983         set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
 984         rds_message_addref(rm);
 985         rm->m_inc.i_conn = conn;
 986
 987         rds_message_populate_header(&rm->m_inc.i_hdr, 0, dport,
 988                                     conn->c_next_tx_seq);
 989         conn->c_next_tx_seq++;
 990         spin_unlock_irqrestore(&conn->c_lock, flags);
 991
 992         rds_stats_inc(s_send_queued);
 993         rds_stats_inc(s_send_pong);
 994
 995         queue_delayed_work(rds_wq, &conn->c_send_w, 0);
 996         rds_message_put(rm);
 997         return 0;
 998
 999 out:
1000         if (rm)
1001                 rds_message_put(rm);
1002         return ret;
1003 }