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 <linux/gfp.h>
  35 #include <net/sock.h>
  36 #include <linux/in.h>
  37 #include <linux/list.h>
  38
  39 #include "rds.h"
  40 #include "rdma.h"
  41
  42 /* When transmitting messages in rds_send_xmit, we need to emerge from
  43  * time to time and briefly release the CPU. Otherwise the softlock watchdog
  44  * will kick our shin.
  45  * Also, it seems fairer to not let one busy connection stall all the
  46  * others.
  47  *
  48  * send_batch_count is the number of times we'll loop in send_xmit. Setting
  49  * it to 0 will restore the old behavior (where we looped until we had
  50  * drained the queue).
  51  */
  52 static int send_batch_count = 64;
  53 module_param(send_batch_count, int, 0444);
  54 MODULE_PARM_DESC(send_batch_count, " batch factor when working the send queue");
  55
  56 /*
  57  * Reset the send state. Caller must hold c_send_lock when calling here.
  58  */
  59 void rds_send_reset(struct rds_connection *conn)
  60 {
  61         struct rds_message *rm, *tmp;
  62         unsigned long flags;
  63
  64         if (conn->c_xmit_rm) {
  65                 /* Tell the user the RDMA op is no longer mapped by the
  66                  * transport. This isn't entirely true (it's flushed out
  67                  * independently) but as the connection is down, there's
  68                  * no ongoing RDMA to/from that memory */
  69                 rds_message_unmapped(conn->c_xmit_rm);
  70                 rds_message_put(conn->c_xmit_rm);
  71                 conn->c_xmit_rm = NULL;
  72         }
  73         conn->c_xmit_sg = 0;
  74         conn->c_xmit_hdr_off = 0;
  75         conn->c_xmit_data_off = 0;
  76         conn->c_xmit_rdma_sent = 0;
  77
  78         conn->c_map_queued = 0;
  79
  80         conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
  81         conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
  82
  83         /* Mark messages as retransmissions, and move them to the send q */
  84         spin_lock_irqsave(&conn->c_lock, flags);
  85         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
  86                 set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
  87                 set_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags);
  88         }
  89         list_splice_init(&conn->c_retrans, &conn->c_send_queue);
  90         spin_unlock_irqrestore(&conn->c_lock, flags);
  91 }
  92
  93 /*
  94  * We're making the concious trade-off here to only send one message
  95  * down the connection at a time.
  96  *   Pro:
  97  *      - tx queueing is a simple fifo list
  98  *      - reassembly is optional and easily done by transports per conn
  99  *      - no per flow rx lookup at all, straight to the socket
 100  *      - less per-frag memory and wire overhead
 101  *   Con:
 102  *      - queued acks can be delayed behind large messages
 103  *   Depends:
 104  *      - small message latency is higher behind queued large messages
 105  *      - large message latency isn't starved by intervening small sends
 106  */
 107 int rds_send_xmit(struct rds_connection *conn)
 108 {
 109         struct rds_message *rm;
 110         unsigned long flags;
 111         unsigned int tmp;
 112         unsigned int send_quota = send_batch_count;
 113         struct scatterlist *sg;
 114         int ret = 0;
 115         int was_empty = 0;
 116         LIST_HEAD(to_be_dropped);
 117
 118         /*
 119          * sendmsg calls here after having queued its message on the send
 120          * queue.  We only have one task feeding the connection at a time.  If
 121          * another thread is already feeding the queue then we back off.  This
 122          * avoids blocking the caller and trading per-connection data between
 123          * caches per message.
 124          *
 125          * The sem holder will issue a retry if they notice that someone queued
 126          * a message after they stopped walking the send queue but before they
 127          * dropped the sem.
 128          */
 129         if (!mutex_trylock(&conn->c_send_lock)) {
 130                 rds_stats_inc(s_send_sem_contention);
 131                 ret = -ENOMEM;
 132                 goto out;
 133         }
 134
 135         if (conn->c_trans->xmit_prepare)
 136                 conn->c_trans->xmit_prepare(conn);
 137
 138         /*
 139          * spin trying to push headers and data down the connection until
 140          * the connection doens't make forward progress.
 141          */
 142         while (--send_quota) {
 143                 /*
 144                  * See if need to send a congestion map update if we're
 145                  * between sending messages.  The send_sem protects our sole
 146                  * use of c_map_offset and _bytes.
 147                  * Note this is used only by transports that define a special
 148                  * xmit_cong_map function. For all others, we create allocate
 149                  * a cong_map message and treat it just like any other send.
 150                  */
 151                 if (conn->c_map_bytes) {
 152                         ret = conn->c_trans->xmit_cong_map(conn, conn->c_lcong,
 153                                                 conn->c_map_offset);
 154                         if (ret <= 0)
 155                                 break;
 156
 157                         conn->c_map_offset += ret;
 158                         conn->c_map_bytes -= ret;
 159                         if (conn->c_map_bytes)
 160                                 continue;
 161                 }
 162
 163                 /* If we're done sending the current message, clear the
 164                  * offset and S/G temporaries.
 165                  */
 166                 rm = conn->c_xmit_rm;
 167                 if (rm != NULL &&
 168                     conn->c_xmit_hdr_off == sizeof(struct rds_header) &&
 169                     conn->c_xmit_sg == rm->m_nents) {
 170                         conn->c_xmit_rm = NULL;
 171                         conn->c_xmit_sg = 0;
 172                         conn->c_xmit_hdr_off = 0;
 173                         conn->c_xmit_data_off = 0;
 174                         conn->c_xmit_rdma_sent = 0;
 175
 176                         /* Release the reference to the previous message. */
 177                         rds_message_put(rm);
 178                         rm = NULL;
 179                 }
 180
 181                 /* If we're asked to send a cong map update, do so.
 182                  */
 183                 if (rm == NULL && test_and_clear_bit(0, &conn->c_map_queued)) {
 184                         if (conn->c_trans->xmit_cong_map != NULL) {
 185                                 conn->c_map_offset = 0;
 186                                 conn->c_map_bytes = sizeof(struct rds_header) +
 187                                         RDS_CONG_MAP_BYTES;
 188                                 continue;
 189                         }
 190
 191                         rm = rds_cong_update_alloc(conn);
 192                         if (IS_ERR(rm)) {
 193                                 ret = PTR_ERR(rm);
 194                                 break;
 195                         }
 196
 197                         conn->c_xmit_rm = rm;
 198                 }
 199
 200                 /*
 201                  * Grab the next message from the send queue, if there is one.
 202                  *
 203                  * c_xmit_rm holds a ref while we're sending this message down
 204                  * the connction.  We can use this ref while holding the
 205                  * send_sem.. rds_send_reset() is serialized with it.
 206                  */
 207                 if (rm == NULL) {
 208                         unsigned int len;
 209
 210                         spin_lock_irqsave(&conn->c_lock, flags);
 211
 212                         if (!list_empty(&conn->c_send_queue)) {
 213                                 rm = list_entry(conn->c_send_queue.next,
 214                                                 struct rds_message,
 215                                                 m_conn_item);
 216                                 rds_message_addref(rm);
 217
 218                                 /*
 219                                  * Move the message from the send queue to the retransmit
 220                                  * list right away.
 221                                  */
 222                                 list_move_tail(&rm->m_conn_item, &conn->c_retrans);
 223                         }
 224
 225                         spin_unlock_irqrestore(&conn->c_lock, flags);
 226
 227                         if (rm == NULL) {
 228                                 was_empty = 1;
 229                                 break;
 230                         }
 231
 232                         /* Unfortunately, the way Infiniband deals with
 233                          * RDMA to a bad MR key is by moving the entire
 234                          * queue pair to error state. We cold possibly
 235                          * recover from that, but right now we drop the
 236                          * connection.
 237                          * Therefore, we never retransmit messages with RDMA ops.
 238                          */
 239                         if (rm->m_rdma_op &&
 240                             test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags)) {
 241                                 spin_lock_irqsave(&conn->c_lock, flags);
 242                                 if (test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags))
 243                                         list_move(&rm->m_conn_item, &to_be_dropped);
 244                                 spin_unlock_irqrestore(&conn->c_lock, flags);
 245                                 rds_message_put(rm);
 246                                 continue;
 247                         }
 248
 249                         /* Require an ACK every once in a while */
 250                         len = ntohl(rm->m_inc.i_hdr.h_len);
 251                         if (conn->c_unacked_packets == 0 ||
 252                             conn->c_unacked_bytes < len) {
 253                                 __set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
 254
 255                                 conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
 256                                 conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
 257                                 rds_stats_inc(s_send_ack_required);
 258                         } else {
 259                                 conn->c_unacked_bytes -= len;
 260                                 conn->c_unacked_packets--;
 261                         }
 262
 263                         conn->c_xmit_rm = rm;
 264                 }
 265
 266                 /*
 267                  * Try and send an rdma message.  Let's see if we can
 268                  * keep this simple and require that the transport either
 269                  * send the whole rdma or none of it.
 270                  */
 271                 if (rm->m_rdma_op && !conn->c_xmit_rdma_sent) {
 272                         ret = conn->c_trans->xmit_rdma(conn, rm->m_rdma_op);
 273                         if (ret)
 274                                 break;
 275                         conn->c_xmit_rdma_sent = 1;
 276                         /* The transport owns the mapped memory for now.
 277                          * You can't unmap it while it's on the send queue */
 278                         set_bit(RDS_MSG_MAPPED, &rm->m_flags);
 279                 }
 280
 281                 if (conn->c_xmit_hdr_off < sizeof(struct rds_header) ||
 282                     conn->c_xmit_sg < rm->m_nents) {
 283                         ret = conn->c_trans->xmit(conn, rm,
 284                                                   conn->c_xmit_hdr_off,
 285                                                   conn->c_xmit_sg,
 286                                                   conn->c_xmit_data_off);
 287                         if (ret <= 0)
 288                                 break;
 289
 290                         if (conn->c_xmit_hdr_off < sizeof(struct rds_header)) {
 291                                 tmp = min_t(int, ret,
 292                                             sizeof(struct rds_header) -
 293                                             conn->c_xmit_hdr_off);
 294                                 conn->c_xmit_hdr_off += tmp;
 295                                 ret -= tmp;
 296                         }
 297
 298                         sg = &rm->m_sg[conn->c_xmit_sg];
 299                         while (ret) {
 300                                 tmp = min_t(int, ret, sg->length -
 301                                                       conn->c_xmit_data_off);
 302                                 conn->c_xmit_data_off += tmp;
 303                                 ret -= tmp;
 304                                 if (conn->c_xmit_data_off == sg->length) {
 305                                         conn->c_xmit_data_off = 0;
 306                                         sg++;
 307                                         conn->c_xmit_sg++;
 308                                         BUG_ON(ret != 0 &&
 309                                                conn->c_xmit_sg == rm->m_nents);
 310                                 }
 311                         }
 312                 }
 313         }
 314
 315         /* Nuke any messages we decided not to retransmit. */
 316         if (!list_empty(&to_be_dropped))
 317                 rds_send_remove_from_sock(&to_be_dropped, RDS_RDMA_DROPPED);
 318
 319         if (conn->c_trans->xmit_complete)
 320                 conn->c_trans->xmit_complete(conn);
 321
 322         /*
 323          * We might be racing with another sender who queued a message but
 324          * backed off on noticing that we held the c_send_lock.  If we check
 325          * for queued messages after dropping the sem then either we'll
 326          * see the queued message or the queuer will get the sem.  If we
 327          * notice the queued message then we trigger an immediate retry.
 328          *
 329          * We need to be careful only to do this when we stopped processing
 330          * the send queue because it was empty.  It's the only way we
 331          * stop processing the loop when the transport hasn't taken
 332          * responsibility for forward progress.
 333          */
 334         mutex_unlock(&conn->c_send_lock);
 335
 336         if (conn->c_map_bytes || (send_quota == 0 && !was_empty)) {
 337                 /* We exhausted the send quota, but there's work left to
 338                  * do. Return and (re-)schedule the send worker.
 339                  */
 340                 ret = -EAGAIN;
 341         }
 342
 343         if (ret == 0 && was_empty) {
 344                 /* A simple bit test would be way faster than taking the
 345                  * spin lock */
 346                 spin_lock_irqsave(&conn->c_lock, flags);
 347                 if (!list_empty(&conn->c_send_queue)) {
 348                         rds_stats_inc(s_send_sem_queue_raced);
 349                         ret = -EAGAIN;
 350                 }
 351                 spin_unlock_irqrestore(&conn->c_lock, flags);
 352         }
 353 out:
 354         return ret;
 355 }
 356
 357 static void rds_send_sndbuf_remove(struct rds_sock *rs, struct rds_message *rm)
 358 {
 359         u32 len = be32_to_cpu(rm->m_inc.i_hdr.h_len);
 360
 361         assert_spin_locked(&rs->rs_lock);
 362
 363         BUG_ON(rs->rs_snd_bytes < len);
 364         rs->rs_snd_bytes -= len;
 365
 366         if (rs->rs_snd_bytes == 0)
 367                 rds_stats_inc(s_send_queue_empty);
 368 }
 369
 370 static inline int rds_send_is_acked(struct rds_message *rm, u64 ack,
 371                                     is_acked_func is_acked)
 372 {
 373         if (is_acked)
 374                 return is_acked(rm, ack);
 375         return be64_to_cpu(rm->m_inc.i_hdr.h_sequence) <= ack;
 376 }
 377
 378 /*
 379  * Returns true if there are no messages on the send and retransmit queues
 380  * which have a sequence number greater than or equal to the given sequence
 381  * number.
 382  */
 383 int rds_send_acked_before(struct rds_connection *conn, u64 seq)
 384 {
 385         struct rds_message *rm, *tmp;
 386         int ret = 1;
 387
 388         spin_lock(&conn->c_lock);
 389
 390         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
 391                 if (be64_to_cpu(rm->m_inc.i_hdr.h_sequence) < seq)
 392                         ret = 0;
 393                 break;
 394         }
 395
 396         list_for_each_entry_safe(rm, tmp, &conn->c_send_queue, m_conn_item) {
 397                 if (be64_to_cpu(rm->m_inc.i_hdr.h_sequence) < seq)
 398                         ret = 0;
 399                 break;
 400         }
 401
 402         spin_unlock(&conn->c_lock);
 403
 404         return ret;
 405 }
 406
 407 /*
 408  * This is pretty similar to what happens below in the ACK
 409  * handling code - except that we call here as soon as we get
 410  * the IB send completion on the RDMA op and the accompanying
 411  * message.
 412  */
 413 void rds_rdma_send_complete(struct rds_message *rm, int status)
 414 {
 415         struct rds_sock *rs = NULL;
 416         struct rds_rdma_op *ro;
 417         struct rds_notifier *notifier;
 418         unsigned long flags;
 419
 420         spin_lock_irqsave(&rm->m_rs_lock, flags);
 421
 422         ro = rm->m_rdma_op;
 423         if (test_bit(RDS_MSG_ON_SOCK, &rm->m_flags) &&
 424             ro && ro->r_notify && ro->r_notifier) {
 425                 notifier = ro->r_notifier;
 426                 rs = rm->m_rs;
 427                 sock_hold(rds_rs_to_sk(rs));
 428
 429                 notifier->n_status = status;
 430                 spin_lock(&rs->rs_lock);
 431                 list_add_tail(&notifier->n_list, &rs->rs_notify_queue);
 432                 spin_unlock(&rs->rs_lock);
 433
 434                 ro->r_notifier = NULL;
 435         }
 436
 437         spin_unlock_irqrestore(&rm->m_rs_lock, flags);
 438
 439         if (rs) {
 440                 rds_wake_sk_sleep(rs);
 441                 sock_put(rds_rs_to_sk(rs));
 442         }
 443 }
 444 EXPORT_SYMBOL_GPL(rds_rdma_send_complete);
 445
 446 /*
 447  * This is the same as rds_rdma_send_complete except we
 448  * don't do any locking - we have all the ingredients (message,
 449  * socket, socket lock) and can just move the notifier.
 450  */
 451 static inline void
 452 __rds_rdma_send_complete(struct rds_sock *rs, struct rds_message *rm, int status)
 453 {
 454         struct rds_rdma_op *ro;
 455
 456         ro = rm->m_rdma_op;
 457         if (ro && ro->r_notify && ro->r_notifier) {
 458                 ro->r_notifier->n_status = status;
 459                 list_add_tail(&ro->r_notifier->n_list, &rs->rs_notify_queue);
 460                 ro->r_notifier = NULL;
 461         }
 462
 463         /* No need to wake the app - caller does this */
 464 }
 465
 466 /*
 467  * This is called from the IB send completion when we detect
 468  * a RDMA operation that failed with remote access error.
 469  * So speed is not an issue here.
 470  */
 471 struct rds_message *rds_send_get_message(struct rds_connection *conn,
 472                                          struct rds_rdma_op *op)
 473 {
 474         struct rds_message *rm, *tmp, *found = NULL;
 475         unsigned long flags;
 476
 477         spin_lock_irqsave(&conn->c_lock, flags);
 478
 479         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
 480                 if (rm->m_rdma_op == op) {
 481                         atomic_inc(&rm->m_refcount);
 482                         found = rm;
 483                         goto out;
 484                 }
 485         }
 486
 487         list_for_each_entry_safe(rm, tmp, &conn->c_send_queue, m_conn_item) {
 488                 if (rm->m_rdma_op == op) {
 489                         atomic_inc(&rm->m_refcount);
 490                         found = rm;
 491                         break;
 492                 }
 493         }
 494
 495 out:
 496         spin_unlock_irqrestore(&conn->c_lock, flags);
 497
 498         return found;
 499 }
 500 EXPORT_SYMBOL_GPL(rds_send_get_message);
 501
 502 /*
 503  * This removes messages from the socket's list if they're on it.  The list
 504  * argument must be private to the caller, we must be able to modify it
 505  * without locks.  The messages must have a reference held for their
 506  * position on the list.  This function will drop that reference after
 507  * removing the messages from the 'messages' list regardless of if it found
 508  * the messages on the socket list or not.
 509  */
 510 void rds_send_remove_from_sock(struct list_head *messages, int status)
 511 {
 512         unsigned long flags;
 513         struct rds_sock *rs = NULL;
 514         struct rds_message *rm;
 515
 516         while (!list_empty(messages)) {
 517                 int was_on_sock = 0;
 518
 519                 rm = list_entry(messages->next, struct rds_message,
 520                                 m_conn_item);
 521                 list_del_init(&rm->m_conn_item);
 522
 523                 /*
 524                  * If we see this flag cleared then we're *sure* that someone
 525                  * else beat us to removing it from the sock.  If we race
 526                  * with their flag update we'll get the lock and then really
 527                  * see that the flag has been cleared.
 528                  *
 529                  * The message spinlock makes sure nobody clears rm->m_rs
 530                  * while we're messing with it. It does not prevent the
 531                  * message from being removed from the socket, though.
 532                  */
 533                 spin_lock_irqsave(&rm->m_rs_lock, flags);
 534                 if (!test_bit(RDS_MSG_ON_SOCK, &rm->m_flags))
 535                         goto unlock_and_drop;
 536
 537                 if (rs != rm->m_rs) {
 538                         if (rs) {
 539                                 rds_wake_sk_sleep(rs);
 540                                 sock_put(rds_rs_to_sk(rs));
 541                         }
 542                         rs = rm->m_rs;
 543                         sock_hold(rds_rs_to_sk(rs));
 544                 }
 545                 spin_lock(&rs->rs_lock);
 546
 547                 if (test_and_clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags)) {
 548                         struct rds_rdma_op *ro = rm->m_rdma_op;
 549                         struct rds_notifier *notifier;
 550
 551                         list_del_init(&rm->m_sock_item);
 552                         rds_send_sndbuf_remove(rs, rm);
 553
 554                         if (ro && ro->r_notifier && (status || ro->r_notify)) {
 555                                 notifier = ro->r_notifier;
 556                                 list_add_tail(&notifier->n_list,
 557                                                 &rs->rs_notify_queue);
 558                                 if (!notifier->n_status)
 559                                         notifier->n_status = status;
 560                                 rm->m_rdma_op->r_notifier = NULL;
 561                         }
 562                         was_on_sock = 1;
 563                         rm->m_rs = NULL;
 564                 }
 565                 spin_unlock(&rs->rs_lock);
 566
 567 unlock_and_drop:
 568                 spin_unlock_irqrestore(&rm->m_rs_lock, flags);
 569                 rds_message_put(rm);
 570                 if (was_on_sock)
 571                         rds_message_put(rm);
 572         }
 573
 574         if (rs) {
 575                 rds_wake_sk_sleep(rs);
 576                 sock_put(rds_rs_to_sk(rs));
 577         }
 578 }
 579
 580 /*
 581  * Transports call here when they've determined that the receiver queued
 582  * messages up to, and including, the given sequence number.  Messages are
 583  * moved to the retrans queue when rds_send_xmit picks them off the send
 584  * queue. This means that in the TCP case, the message may not have been
 585  * assigned the m_ack_seq yet - but that's fine as long as tcp_is_acked
 586  * checks the RDS_MSG_HAS_ACK_SEQ bit.
 587  *
 588  * XXX It's not clear to me how this is safely serialized with socket
 589  * destruction.  Maybe it should bail if it sees SOCK_DEAD.
 590  */
 591 void rds_send_drop_acked(struct rds_connection *conn, u64 ack,
 592                          is_acked_func is_acked)
 593 {
 594         struct rds_message *rm, *tmp;
 595         unsigned long flags;
 596         LIST_HEAD(list);
 597
 598         spin_lock_irqsave(&conn->c_lock, flags);
 599
 600         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
 601                 if (!rds_send_is_acked(rm, ack, is_acked))
 602                         break;
 603
 604                 list_move(&rm->m_conn_item, &list);
 605                 clear_bit(RDS_MSG_ON_CONN, &rm->m_flags);
 606         }
 607
 608         /* order flag updates with spin locks */
 609         if (!list_empty(&list))
 610                 smp_mb__after_clear_bit();
 611
 612         spin_unlock_irqrestore(&conn->c_lock, flags);
 613
 614         /* now remove the messages from the sock list as needed */
 615         rds_send_remove_from_sock(&list, RDS_RDMA_SUCCESS);
 616 }
 617 EXPORT_SYMBOL_GPL(rds_send_drop_acked);
 618
 619 void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest)
 620 {
 621         struct rds_message *rm, *tmp;
 622         struct rds_connection *conn;
 623         unsigned long flags;
 624         LIST_HEAD(list);
 625
 626         /* get all the messages we're dropping under the rs lock */
 627         spin_lock_irqsave(&rs->rs_lock, flags);
 628
 629         list_for_each_entry_safe(rm, tmp, &rs->rs_send_queue, m_sock_item) {
 630                 if (dest && (dest->sin_addr.s_addr != rm->m_daddr ||
 631                              dest->sin_port != rm->m_inc.i_hdr.h_dport))
 632                         continue;
 633
 634                 list_move(&rm->m_sock_item, &list);
 635                 rds_send_sndbuf_remove(rs, rm);
 636                 clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags);
 637         }
 638
 639         /* order flag updates with the rs lock */
 640         smp_mb__after_clear_bit();
 641
 642         spin_unlock_irqrestore(&rs->rs_lock, flags);
 643
 644         if (list_empty(&list))
 645                 return;
 646
 647         /* Remove the messages from the conn */
 648         list_for_each_entry(rm, &list, m_sock_item) {
 649
 650                 conn = rm->m_inc.i_conn;
 651
 652                 spin_lock_irqsave(&conn->c_lock, flags);
 653                 /*
 654                  * Maybe someone else beat us to removing rm from the conn.
 655                  * If we race with their flag update we'll get the lock and
 656                  * then really see that the flag has been cleared.
 657                  */
 658                 if (!test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags)) {
 659                         spin_unlock_irqrestore(&conn->c_lock, flags);
 660                         continue;
 661                 }
 662                 list_del_init(&rm->m_conn_item);
 663                 spin_unlock_irqrestore(&conn->c_lock, flags);
 664
 665                 /*
 666                  * Couldn't grab m_rs_lock in top loop (lock ordering),
 667                  * but we can now.
 668                  */
 669                 spin_lock_irqsave(&rm->m_rs_lock, flags);
 670
 671                 spin_lock(&rs->rs_lock);
 672                 __rds_rdma_send_complete(rs, rm, RDS_RDMA_CANCELED);
 673                 spin_unlock(&rs->rs_lock);
 674
 675                 rm->m_rs = NULL;
 676                 spin_unlock_irqrestore(&rm->m_rs_lock, flags);
 677
 678                 rds_message_put(rm);
 679         }
 680
 681         rds_wake_sk_sleep(rs);
 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_sndtimeo(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                 rs->rs_seen_congestion = 1;
 897                 goto out;
 898         }
 899
 900         while (!rds_send_queue_rm(rs, conn, rm, rs->rs_bound_port,
 901                                   dport, &queued)) {
 902                 rds_stats_inc(s_send_queue_full);
 903                 /* XXX make sure this is reasonable */
 904                 if (payload_len > rds_sk_sndbuf(rs)) {
 905                         ret = -EMSGSIZE;
 906                         goto out;
 907                 }
 908                 if (nonblock) {
 909                         ret = -EAGAIN;
 910                         goto out;
 911                 }
 912
 913                 timeo = wait_event_interruptible_timeout(*sk_sleep(sk),
 914                                         rds_send_queue_rm(rs, conn, rm,
 915                                                           rs->rs_bound_port,
 916                                                           dport,
 917                                                           &queued),
 918                                         timeo);
 919                 rdsdebug("sendmsg woke queued %d timeo %ld\n", queued, timeo);
 920                 if (timeo > 0 || timeo == MAX_SCHEDULE_TIMEOUT)
 921                         continue;
 922
 923                 ret = timeo;
 924                 if (ret == 0)
 925                         ret = -ETIMEDOUT;
 926                 goto out;
 927         }
 928
 929         /*
 930          * By now we've committed to the send.  We reuse rds_send_worker()
 931          * to retry sends in the rds thread if the transport asks us to.
 932          */
 933         rds_stats_inc(s_send_queued);
 934
 935         if (!test_bit(RDS_LL_SEND_FULL, &conn->c_flags))
 936                 rds_send_worker(&conn->c_send_w.work);
 937
 938         rds_message_put(rm);
 939         return payload_len;
 940
 941 out:
 942         /* If the user included a RDMA_MAP cmsg, we allocated a MR on the fly.
 943          * If the sendmsg goes through, we keep the MR. If it fails with EAGAIN
 944          * or in any other way, we need to destroy the MR again */
 945         if (allocated_mr)
 946                 rds_rdma_unuse(rs, rds_rdma_cookie_key(rm->m_rdma_cookie), 1);
 947
 948         if (rm)
 949                 rds_message_put(rm);
 950         return ret;
 951 }
 952
 953 /*
 954  * Reply to a ping packet.
 955  */
 956 int
 957 rds_send_pong(struct rds_connection *conn, __be16 dport)
 958 {
 959         struct rds_message *rm;
 960         unsigned long flags;
 961         int ret = 0;
 962
 963         rm = rds_message_alloc(0, GFP_ATOMIC);
 964         if (rm == NULL) {
 965                 ret = -ENOMEM;
 966                 goto out;
 967         }
 968
 969         rm->m_daddr = conn->c_faddr;
 970
 971         /* If the connection is down, trigger a connect. We may
 972          * have scheduled a delayed reconnect however - in this case
 973          * we should not interfere.
 974          */
 975         if (rds_conn_state(conn) == RDS_CONN_DOWN &&
 976             !test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
 977                 queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
 978
 979         ret = rds_cong_wait(conn->c_fcong, dport, 1, NULL);
 980         if (ret)
 981                 goto out;
 982
 983         spin_lock_irqsave(&conn->c_lock, flags);
 984         list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
 985         set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
 986         rds_message_addref(rm);
 987         rm->m_inc.i_conn = conn;
 988
 989         rds_message_populate_header(&rm->m_inc.i_hdr, 0, dport,
 990                                     conn->c_next_tx_seq);
 991         conn->c_next_tx_seq++;
 992         spin_unlock_irqrestore(&conn->c_lock, flags);
 993
 994         rds_stats_inc(s_send_queued);
 995         rds_stats_inc(s_send_pong);
 996
 997         queue_delayed_work(rds_wq, &conn->c_send_w, 0);
 998         rds_message_put(rm);
 999         return 0;
1000
1001 out:
1002         if (rm)
1003                 rds_message_put(rm);
1004         return ret;
1005 }