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/moduleparam.h>
  35 #include <linux/gfp.h>
  36 #include <net/sock.h>
  37 #include <linux/in.h>
  38 #include <linux/list.h>
  39 #include <linux/ratelimit.h>
  40 #include <linux/export.h>
  41 #include <linux/sizes.h>
  42
  43 #include "rds.h"
  44
  45 /* When transmitting messages in rds_send_xmit, we need to emerge from
  46  * time to time and briefly release the CPU. Otherwise the softlock watchdog
  47  * will kick our shin.
  48  * Also, it seems fairer to not let one busy connection stall all the
  49  * others.
  50  *
  51  * send_batch_count is the number of times we'll loop in send_xmit. Setting
  52  * it to 0 will restore the old behavior (where we looped until we had
  53  * drained the queue).
  54  */
  55 static int send_batch_count = SZ_1K;
  56 module_param(send_batch_count, int, 0444);
  57 MODULE_PARM_DESC(send_batch_count, " batch factor when working the send queue");
  58
  59 static void rds_send_remove_from_sock(struct list_head *messages, int status);
  60
  61 /*
  62  * Reset the send state.  Callers must ensure that this doesn't race with
  63  * rds_send_xmit().
  64  */
  65 void rds_send_reset(struct rds_connection *conn)
  66 {
  67         struct rds_message *rm, *tmp;
  68         unsigned long flags;
  69
  70         if (conn->c_xmit_rm) {
  71                 rm = conn->c_xmit_rm;
  72                 conn->c_xmit_rm = NULL;
  73                 /* Tell the user the RDMA op is no longer mapped by the
  74                  * transport. This isn't entirely true (it's flushed out
  75                  * independently) but as the connection is down, there's
  76                  * no ongoing RDMA to/from that memory */
  77                 rds_message_unmapped(rm);
  78                 rds_message_put(rm);
  79         }
  80
  81         conn->c_xmit_sg = 0;
  82         conn->c_xmit_hdr_off = 0;
  83         conn->c_xmit_data_off = 0;
  84         conn->c_xmit_atomic_sent = 0;
  85         conn->c_xmit_rdma_sent = 0;
  86         conn->c_xmit_data_sent = 0;
  87
  88         conn->c_map_queued = 0;
  89
  90         conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
  91         conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
  92
  93         /* Mark messages as retransmissions, and move them to the send q */
  94         spin_lock_irqsave(&conn->c_lock, flags);
  95         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
  96                 set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
  97                 set_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags);
  98         }
  99         list_splice_init(&conn->c_retrans, &conn->c_send_queue);
 100         spin_unlock_irqrestore(&conn->c_lock, flags);
 101 }
 102
 103 static int acquire_in_xmit(struct rds_connection *conn)
 104 {
 105         return test_and_set_bit(RDS_IN_XMIT, &conn->c_flags) == 0;
 106 }
 107
 108 static void release_in_xmit(struct rds_connection *conn)
 109 {
 110         clear_bit(RDS_IN_XMIT, &conn->c_flags);
 111         smp_mb__after_atomic();
 112         /*
 113          * We don't use wait_on_bit()/wake_up_bit() because our waking is in a
 114          * hot path and finding waiters is very rare.  We don't want to walk
 115          * the system-wide hashed waitqueue buckets in the fast path only to
 116          * almost never find waiters.
 117          */
 118         if (waitqueue_active(&conn->c_waitq))
 119                 wake_up_all(&conn->c_waitq);
 120 }
 121
 122 /*
 123  * We're making the conscious trade-off here to only send one message
 124  * down the connection at a time.
 125  *   Pro:
 126  *      - tx queueing is a simple fifo list
 127  *      - reassembly is optional and easily done by transports per conn
 128  *      - no per flow rx lookup at all, straight to the socket
 129  *      - less per-frag memory and wire overhead
 130  *   Con:
 131  *      - queued acks can be delayed behind large messages
 132  *   Depends:
 133  *      - small message latency is higher behind queued large messages
 134  *      - large message latency isn't starved by intervening small sends
 135  */
 136 int rds_send_xmit(struct rds_connection *conn)
 137 {
 138         struct rds_message *rm;
 139         unsigned long flags;
 140         unsigned int tmp;
 141         struct scatterlist *sg;
 142         int ret = 0;
 143         LIST_HEAD(to_be_dropped);
 144         int batch_count;
 145         unsigned long send_gen = 0;
 146
 147 restart:
 148         batch_count = 0;
 149
 150         /*
 151          * sendmsg calls here after having queued its message on the send
 152          * queue.  We only have one task feeding the connection at a time.  If
 153          * another thread is already feeding the queue then we back off.  This
 154          * avoids blocking the caller and trading per-connection data between
 155          * caches per message.
 156          */
 157         if (!acquire_in_xmit(conn)) {
 158                 rds_stats_inc(s_send_lock_contention);
 159                 ret = -ENOMEM;
 160                 goto out;
 161         }
 162
 163         /*
 164          * we record the send generation after doing the xmit acquire.
 165          * if someone else manages to jump in and do some work, we'll use
 166          * this to avoid a goto restart farther down.
 167          *
 168          * The acquire_in_xmit() check above ensures that only one
 169          * caller can increment c_send_gen at any time.
 170          */
 171         conn->c_send_gen++;
 172         send_gen = conn->c_send_gen;
 173
 174         /*
 175          * rds_conn_shutdown() sets the conn state and then tests RDS_IN_XMIT,
 176          * we do the opposite to avoid races.
 177          */
 178         if (!rds_conn_up(conn)) {
 179                 release_in_xmit(conn);
 180                 ret = 0;
 181                 goto out;
 182         }
 183
 184         if (conn->c_trans->xmit_prepare)
 185                 conn->c_trans->xmit_prepare(conn);
 186
 187         /*
 188          * spin trying to push headers and data down the connection until
 189          * the connection doesn't make forward progress.
 190          */
 191         while (1) {
 192
 193                 rm = conn->c_xmit_rm;
 194
 195                 /*
 196                  * If between sending messages, we can send a pending congestion
 197                  * map update.
 198                  */
 199                 if (!rm && test_and_clear_bit(0, &conn->c_map_queued)) {
 200                         rm = rds_cong_update_alloc(conn);
 201                         if (IS_ERR(rm)) {
 202                                 ret = PTR_ERR(rm);
 203                                 break;
 204                         }
 205                         rm->data.op_active = 1;
 206
 207                         conn->c_xmit_rm = rm;
 208                 }
 209
 210                 /*
 211                  * If not already working on one, grab the next message.
 212                  *
 213                  * c_xmit_rm holds a ref while we're sending this message down
 214                  * the connction.  We can use this ref while holding the
 215                  * send_sem.. rds_send_reset() is serialized with it.
 216                  */
 217                 if (!rm) {
 218                         unsigned int len;
 219
 220                         batch_count++;
 221
 222                         /* we want to process as big a batch as we can, but
 223                          * we also want to avoid softlockups.  If we've been
 224                          * through a lot of messages, lets back off and see
 225                          * if anyone else jumps in
 226                          */
 227                         if (batch_count >= send_batch_count)
 228                                 goto over_batch;
 229
 230                         spin_lock_irqsave(&conn->c_lock, flags);
 231
 232                         if (!list_empty(&conn->c_send_queue)) {
 233                                 rm = list_entry(conn->c_send_queue.next,
 234                                                 struct rds_message,
 235                                                 m_conn_item);
 236                                 rds_message_addref(rm);
 237
 238                                 /*
 239                                  * Move the message from the send queue to the retransmit
 240                                  * list right away.
 241                                  */
 242                                 list_move_tail(&rm->m_conn_item, &conn->c_retrans);
 243                         }
 244
 245                         spin_unlock_irqrestore(&conn->c_lock, flags);
 246
 247                         if (!rm)
 248                                 break;
 249
 250                         /* Unfortunately, the way Infiniband deals with
 251                          * RDMA to a bad MR key is by moving the entire
 252                          * queue pair to error state. We cold possibly
 253                          * recover from that, but right now we drop the
 254                          * connection.
 255                          * Therefore, we never retransmit messages with RDMA ops.
 256                          */
 257                         if (rm->rdma.op_active &&
 258                             test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags)) {
 259                                 spin_lock_irqsave(&conn->c_lock, flags);
 260                                 if (test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags))
 261                                         list_move(&rm->m_conn_item, &to_be_dropped);
 262                                 spin_unlock_irqrestore(&conn->c_lock, flags);
 263                                 continue;
 264                         }
 265
 266                         /* Require an ACK every once in a while */
 267                         len = ntohl(rm->m_inc.i_hdr.h_len);
 268                         if (conn->c_unacked_packets == 0 ||
 269                             conn->c_unacked_bytes < len) {
 270                                 __set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
 271
 272                                 conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
 273                                 conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
 274                                 rds_stats_inc(s_send_ack_required);
 275                         } else {
 276                                 conn->c_unacked_bytes -= len;
 277                                 conn->c_unacked_packets--;
 278                         }
 279
 280                         conn->c_xmit_rm = rm;
 281                 }
 282
 283                 /* The transport either sends the whole rdma or none of it */
 284                 if (rm->rdma.op_active && !conn->c_xmit_rdma_sent) {
 285                         rm->m_final_op = &rm->rdma;
 286                         /* The transport owns the mapped memory for now.
 287                          * You can't unmap it while it's on the send queue
 288                          */
 289                         set_bit(RDS_MSG_MAPPED, &rm->m_flags);
 290                         ret = conn->c_trans->xmit_rdma(conn, &rm->rdma);
 291                         if (ret) {
 292                                 clear_bit(RDS_MSG_MAPPED, &rm->m_flags);
 293                                 wake_up_interruptible(&rm->m_flush_wait);
 294                                 break;
 295                         }
 296                         conn->c_xmit_rdma_sent = 1;
 297
 298                 }
 299
 300                 if (rm->atomic.op_active && !conn->c_xmit_atomic_sent) {
 301                         rm->m_final_op = &rm->atomic;
 302                         /* The transport owns the mapped memory for now.
 303                          * You can't unmap it while it's on the send queue
 304                          */
 305                         set_bit(RDS_MSG_MAPPED, &rm->m_flags);
 306                         ret = conn->c_trans->xmit_atomic(conn, &rm->atomic);
 307                         if (ret) {
 308                                 clear_bit(RDS_MSG_MAPPED, &rm->m_flags);
 309                                 wake_up_interruptible(&rm->m_flush_wait);
 310                                 break;
 311                         }
 312                         conn->c_xmit_atomic_sent = 1;
 313
 314                 }
 315
 316                 /*
 317                  * A number of cases require an RDS header to be sent
 318                  * even if there is no data.
 319                  * We permit 0-byte sends; rds-ping depends on this.
 320                  * However, if there are exclusively attached silent ops,
 321                  * we skip the hdr/data send, to enable silent operation.
 322                  */
 323                 if (rm->data.op_nents == 0) {
 324                         int ops_present;
 325                         int all_ops_are_silent = 1;
 326
 327                         ops_present = (rm->atomic.op_active || rm->rdma.op_active);
 328                         if (rm->atomic.op_active && !rm->atomic.op_silent)
 329                                 all_ops_are_silent = 0;
 330                         if (rm->rdma.op_active && !rm->rdma.op_silent)
 331                                 all_ops_are_silent = 0;
 332
 333                         if (ops_present && all_ops_are_silent
 334                             && !rm->m_rdma_cookie)
 335                                 rm->data.op_active = 0;
 336                 }
 337
 338                 if (rm->data.op_active && !conn->c_xmit_data_sent) {
 339                         rm->m_final_op = &rm->data;
 340                         ret = conn->c_trans->xmit(conn, rm,
 341                                                   conn->c_xmit_hdr_off,
 342                                                   conn->c_xmit_sg,
 343                                                   conn->c_xmit_data_off);
 344                         if (ret <= 0)
 345                                 break;
 346
 347                         if (conn->c_xmit_hdr_off < sizeof(struct rds_header)) {
 348                                 tmp = min_t(int, ret,
 349                                             sizeof(struct rds_header) -
 350                                             conn->c_xmit_hdr_off);
 351                                 conn->c_xmit_hdr_off += tmp;
 352                                 ret -= tmp;
 353                         }
 354
 355                         sg = &rm->data.op_sg[conn->c_xmit_sg];
 356                         while (ret) {
 357                                 tmp = min_t(int, ret, sg->length -
 358                                                       conn->c_xmit_data_off);
 359                                 conn->c_xmit_data_off += tmp;
 360                                 ret -= tmp;
 361                                 if (conn->c_xmit_data_off == sg->length) {
 362                                         conn->c_xmit_data_off = 0;
 363                                         sg++;
 364                                         conn->c_xmit_sg++;
 365                                         BUG_ON(ret != 0 &&
 366                                                conn->c_xmit_sg == rm->data.op_nents);
 367                                 }
 368                         }
 369
 370                         if (conn->c_xmit_hdr_off == sizeof(struct rds_header) &&
 371                             (conn->c_xmit_sg == rm->data.op_nents))
 372                                 conn->c_xmit_data_sent = 1;
 373                 }
 374
 375                 /*
 376                  * A rm will only take multiple times through this loop
 377                  * if there is a data op. Thus, if the data is sent (or there was
 378                  * none), then we're done with the rm.
 379                  */
 380                 if (!rm->data.op_active || conn->c_xmit_data_sent) {
 381                         conn->c_xmit_rm = NULL;
 382                         conn->c_xmit_sg = 0;
 383                         conn->c_xmit_hdr_off = 0;
 384                         conn->c_xmit_data_off = 0;
 385                         conn->c_xmit_rdma_sent = 0;
 386                         conn->c_xmit_atomic_sent = 0;
 387                         conn->c_xmit_data_sent = 0;
 388
 389                         rds_message_put(rm);
 390                 }
 391         }
 392
 393 over_batch:
 394         if (conn->c_trans->xmit_complete)
 395                 conn->c_trans->xmit_complete(conn);
 396         release_in_xmit(conn);
 397
 398         /* Nuke any messages we decided not to retransmit. */
 399         if (!list_empty(&to_be_dropped)) {
 400                 /* irqs on here, so we can put(), unlike above */
 401                 list_for_each_entry(rm, &to_be_dropped, m_conn_item)
 402                         rds_message_put(rm);
 403                 rds_send_remove_from_sock(&to_be_dropped, RDS_RDMA_DROPPED);
 404         }
 405
 406         /*
 407          * Other senders can queue a message after we last test the send queue
 408          * but before we clear RDS_IN_XMIT.  In that case they'd back off and
 409          * not try and send their newly queued message.  We need to check the
 410          * send queue after having cleared RDS_IN_XMIT so that their message
 411          * doesn't get stuck on the send queue.
 412          *
 413          * If the transport cannot continue (i.e ret != 0), then it must
 414          * call us when more room is available, such as from the tx
 415          * completion handler.
 416          *
 417          * We have an extra generation check here so that if someone manages
 418          * to jump in after our release_in_xmit, we'll see that they have done
 419          * some work and we will skip our goto
 420          */
 421         if (ret == 0) {
 422                 smp_mb();
 423                 if ((test_bit(0, &conn->c_map_queued) ||
 424                      !list_empty(&conn->c_send_queue)) &&
 425                     send_gen == conn->c_send_gen) {
 426                         rds_stats_inc(s_send_lock_queue_raced);
 427                         if (batch_count < send_batch_count)
 428                                 goto restart;
 429                         queue_delayed_work(rds_wq, &conn->c_send_w, 1);
 430                 }
 431         }
 432 out:
 433         return ret;
 434 }
 435
 436 static void rds_send_sndbuf_remove(struct rds_sock *rs, struct rds_message *rm)
 437 {
 438         u32 len = be32_to_cpu(rm->m_inc.i_hdr.h_len);
 439
 440         assert_spin_locked(&rs->rs_lock);
 441
 442         BUG_ON(rs->rs_snd_bytes < len);
 443         rs->rs_snd_bytes -= len;
 444
 445         if (rs->rs_snd_bytes == 0)
 446                 rds_stats_inc(s_send_queue_empty);
 447 }
 448
 449 static inline int rds_send_is_acked(struct rds_message *rm, u64 ack,
 450                                     is_acked_func is_acked)
 451 {
 452         if (is_acked)
 453                 return is_acked(rm, ack);
 454         return be64_to_cpu(rm->m_inc.i_hdr.h_sequence) <= ack;
 455 }
 456
 457 /*
 458  * This is pretty similar to what happens below in the ACK
 459  * handling code - except that we call here as soon as we get
 460  * the IB send completion on the RDMA op and the accompanying
 461  * message.
 462  */
 463 void rds_rdma_send_complete(struct rds_message *rm, int status)
 464 {
 465         struct rds_sock *rs = NULL;
 466         struct rm_rdma_op *ro;
 467         struct rds_notifier *notifier;
 468         unsigned long flags;
 469
 470         spin_lock_irqsave(&rm->m_rs_lock, flags);
 471
 472         ro = &rm->rdma;
 473         if (test_bit(RDS_MSG_ON_SOCK, &rm->m_flags) &&
 474             ro->op_active && ro->op_notify && ro->op_notifier) {
 475                 notifier = ro->op_notifier;
 476                 rs = rm->m_rs;
 477                 sock_hold(rds_rs_to_sk(rs));
 478
 479                 notifier->n_status = status;
 480                 spin_lock(&rs->rs_lock);
 481                 list_add_tail(&notifier->n_list, &rs->rs_notify_queue);
 482                 spin_unlock(&rs->rs_lock);
 483
 484                 ro->op_notifier = NULL;
 485         }
 486
 487         spin_unlock_irqrestore(&rm->m_rs_lock, flags);
 488
 489         if (rs) {
 490                 rds_wake_sk_sleep(rs);
 491                 sock_put(rds_rs_to_sk(rs));
 492         }
 493 }
 494 EXPORT_SYMBOL_GPL(rds_rdma_send_complete);
 495
 496 /*
 497  * Just like above, except looks at atomic op
 498  */
 499 void rds_atomic_send_complete(struct rds_message *rm, int status)
 500 {
 501         struct rds_sock *rs = NULL;
 502         struct rm_atomic_op *ao;
 503         struct rds_notifier *notifier;
 504         unsigned long flags;
 505
 506         spin_lock_irqsave(&rm->m_rs_lock, flags);
 507
 508         ao = &rm->atomic;
 509         if (test_bit(RDS_MSG_ON_SOCK, &rm->m_flags)
 510             && ao->op_active && ao->op_notify && ao->op_notifier) {
 511                 notifier = ao->op_notifier;
 512                 rs = rm->m_rs;
 513                 sock_hold(rds_rs_to_sk(rs));
 514
 515                 notifier->n_status = status;
 516                 spin_lock(&rs->rs_lock);
 517                 list_add_tail(&notifier->n_list, &rs->rs_notify_queue);
 518                 spin_unlock(&rs->rs_lock);
 519
 520                 ao->op_notifier = NULL;
 521         }
 522
 523         spin_unlock_irqrestore(&rm->m_rs_lock, flags);
 524
 525         if (rs) {
 526                 rds_wake_sk_sleep(rs);
 527                 sock_put(rds_rs_to_sk(rs));
 528         }
 529 }
 530 EXPORT_SYMBOL_GPL(rds_atomic_send_complete);
 531
 532 /*
 533  * This is the same as rds_rdma_send_complete except we
 534  * don't do any locking - we have all the ingredients (message,
 535  * socket, socket lock) and can just move the notifier.
 536  */
 537 static inline void
 538 __rds_send_complete(struct rds_sock *rs, struct rds_message *rm, int status)
 539 {
 540         struct rm_rdma_op *ro;
 541         struct rm_atomic_op *ao;
 542
 543         ro = &rm->rdma;
 544         if (ro->op_active && ro->op_notify && ro->op_notifier) {
 545                 ro->op_notifier->n_status = status;
 546                 list_add_tail(&ro->op_notifier->n_list, &rs->rs_notify_queue);
 547                 ro->op_notifier = NULL;
 548         }
 549
 550         ao = &rm->atomic;
 551         if (ao->op_active && ao->op_notify && ao->op_notifier) {
 552                 ao->op_notifier->n_status = status;
 553                 list_add_tail(&ao->op_notifier->n_list, &rs->rs_notify_queue);
 554                 ao->op_notifier = NULL;
 555         }
 556
 557         /* No need to wake the app - caller does this */
 558 }
 559
 560 /*
 561  * This is called from the IB send completion when we detect
 562  * a RDMA operation that failed with remote access error.
 563  * So speed is not an issue here.
 564  */
 565 struct rds_message *rds_send_get_message(struct rds_connection *conn,
 566                                          struct rm_rdma_op *op)
 567 {
 568         struct rds_message *rm, *tmp, *found = NULL;
 569         unsigned long flags;
 570
 571         spin_lock_irqsave(&conn->c_lock, flags);
 572
 573         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
 574                 if (&rm->rdma == op) {
 575                         atomic_inc(&rm->m_refcount);
 576                         found = rm;
 577                         goto out;
 578                 }
 579         }
 580
 581         list_for_each_entry_safe(rm, tmp, &conn->c_send_queue, m_conn_item) {
 582                 if (&rm->rdma == op) {
 583                         atomic_inc(&rm->m_refcount);
 584                         found = rm;
 585                         break;
 586                 }
 587         }
 588
 589 out:
 590         spin_unlock_irqrestore(&conn->c_lock, flags);
 591
 592         return found;
 593 }
 594 EXPORT_SYMBOL_GPL(rds_send_get_message);
 595
 596 /*
 597  * This removes messages from the socket's list if they're on it.  The list
 598  * argument must be private to the caller, we must be able to modify it
 599  * without locks.  The messages must have a reference held for their
 600  * position on the list.  This function will drop that reference after
 601  * removing the messages from the 'messages' list regardless of if it found
 602  * the messages on the socket list or not.
 603  */
 604 static void rds_send_remove_from_sock(struct list_head *messages, int status)
 605 {
 606         unsigned long flags;
 607         struct rds_sock *rs = NULL;
 608         struct rds_message *rm;
 609
 610         while (!list_empty(messages)) {
 611                 int was_on_sock = 0;
 612
 613                 rm = list_entry(messages->next, struct rds_message,
 614                                 m_conn_item);
 615                 list_del_init(&rm->m_conn_item);
 616
 617                 /*
 618                  * If we see this flag cleared then we're *sure* that someone
 619                  * else beat us to removing it from the sock.  If we race
 620                  * with their flag update we'll get the lock and then really
 621                  * see that the flag has been cleared.
 622                  *
 623                  * The message spinlock makes sure nobody clears rm->m_rs
 624                  * while we're messing with it. It does not prevent the
 625                  * message from being removed from the socket, though.
 626                  */
 627                 spin_lock_irqsave(&rm->m_rs_lock, flags);
 628                 if (!test_bit(RDS_MSG_ON_SOCK, &rm->m_flags))
 629                         goto unlock_and_drop;
 630
 631                 if (rs != rm->m_rs) {
 632                         if (rs) {
 633                                 rds_wake_sk_sleep(rs);
 634                                 sock_put(rds_rs_to_sk(rs));
 635                         }
 636                         rs = rm->m_rs;
 637                         if (rs)
 638                                 sock_hold(rds_rs_to_sk(rs));
 639                 }
 640                 if (!rs)
 641                         goto unlock_and_drop;
 642                 spin_lock(&rs->rs_lock);
 643
 644                 if (test_and_clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags)) {
 645                         struct rm_rdma_op *ro = &rm->rdma;
 646                         struct rds_notifier *notifier;
 647
 648                         list_del_init(&rm->m_sock_item);
 649                         rds_send_sndbuf_remove(rs, rm);
 650
 651                         if (ro->op_active && ro->op_notifier &&
 652                                (ro->op_notify || (ro->op_recverr && status))) {
 653                                 notifier = ro->op_notifier;
 654                                 list_add_tail(&notifier->n_list,
 655                                                 &rs->rs_notify_queue);
 656                                 if (!notifier->n_status)
 657                                         notifier->n_status = status;
 658                                 rm->rdma.op_notifier = NULL;
 659                         }
 660                         was_on_sock = 1;
 661                         rm->m_rs = NULL;
 662                 }
 663                 spin_unlock(&rs->rs_lock);
 664
 665 unlock_and_drop:
 666                 spin_unlock_irqrestore(&rm->m_rs_lock, flags);
 667                 rds_message_put(rm);
 668                 if (was_on_sock)
 669                         rds_message_put(rm);
 670         }
 671
 672         if (rs) {
 673                 rds_wake_sk_sleep(rs);
 674                 sock_put(rds_rs_to_sk(rs));
 675         }
 676 }
 677
 678 /*
 679  * Transports call here when they've determined that the receiver queued
 680  * messages up to, and including, the given sequence number.  Messages are
 681  * moved to the retrans queue when rds_send_xmit picks them off the send
 682  * queue. This means that in the TCP case, the message may not have been
 683  * assigned the m_ack_seq yet - but that's fine as long as tcp_is_acked
 684  * checks the RDS_MSG_HAS_ACK_SEQ bit.
 685  */
 686 void rds_send_drop_acked(struct rds_connection *conn, u64 ack,
 687                          is_acked_func is_acked)
 688 {
 689         struct rds_message *rm, *tmp;
 690         unsigned long flags;
 691         LIST_HEAD(list);
 692
 693         spin_lock_irqsave(&conn->c_lock, flags);
 694
 695         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
 696                 if (!rds_send_is_acked(rm, ack, is_acked))
 697                         break;
 698
 699                 list_move(&rm->m_conn_item, &list);
 700                 clear_bit(RDS_MSG_ON_CONN, &rm->m_flags);
 701         }
 702
 703         /* order flag updates with spin locks */
 704         if (!list_empty(&list))
 705                 smp_mb__after_atomic();
 706
 707         spin_unlock_irqrestore(&conn->c_lock, flags);
 708
 709         /* now remove the messages from the sock list as needed */
 710         rds_send_remove_from_sock(&list, RDS_RDMA_SUCCESS);
 711 }
 712 EXPORT_SYMBOL_GPL(rds_send_drop_acked);
 713
 714 void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest)
 715 {
 716         struct rds_message *rm, *tmp;
 717         struct rds_connection *conn;
 718         unsigned long flags;
 719         LIST_HEAD(list);
 720
 721         /* get all the messages we're dropping under the rs lock */
 722         spin_lock_irqsave(&rs->rs_lock, flags);
 723
 724         list_for_each_entry_safe(rm, tmp, &rs->rs_send_queue, m_sock_item) {
 725                 if (dest && (dest->sin_addr.s_addr != rm->m_daddr ||
 726                              dest->sin_port != rm->m_inc.i_hdr.h_dport))
 727                         continue;
 728
 729                 list_move(&rm->m_sock_item, &list);
 730                 rds_send_sndbuf_remove(rs, rm);
 731                 clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags);
 732         }
 733
 734         /* order flag updates with the rs lock */
 735         smp_mb__after_atomic();
 736
 737         spin_unlock_irqrestore(&rs->rs_lock, flags);
 738
 739         if (list_empty(&list))
 740                 return;
 741
 742         /* Remove the messages from the conn */
 743         list_for_each_entry(rm, &list, m_sock_item) {
 744
 745                 conn = rm->m_inc.i_conn;
 746
 747                 spin_lock_irqsave(&conn->c_lock, flags);
 748                 /*
 749                  * Maybe someone else beat us to removing rm from the conn.
 750                  * If we race with their flag update we'll get the lock and
 751                  * then really see that the flag has been cleared.
 752                  */
 753                 if (!test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags)) {
 754                         spin_unlock_irqrestore(&conn->c_lock, flags);
 755                         spin_lock_irqsave(&rm->m_rs_lock, flags);
 756                         rm->m_rs = NULL;
 757                         spin_unlock_irqrestore(&rm->m_rs_lock, flags);
 758                         continue;
 759                 }
 760                 list_del_init(&rm->m_conn_item);
 761                 spin_unlock_irqrestore(&conn->c_lock, flags);
 762
 763                 /*
 764                  * Couldn't grab m_rs_lock in top loop (lock ordering),
 765                  * but we can now.
 766                  */
 767                 spin_lock_irqsave(&rm->m_rs_lock, flags);
 768
 769                 spin_lock(&rs->rs_lock);
 770                 __rds_send_complete(rs, rm, RDS_RDMA_CANCELED);
 771                 spin_unlock(&rs->rs_lock);
 772
 773                 rm->m_rs = NULL;
 774                 spin_unlock_irqrestore(&rm->m_rs_lock, flags);
 775
 776                 rds_message_put(rm);
 777         }
 778
 779         rds_wake_sk_sleep(rs);
 780
 781         while (!list_empty(&list)) {
 782                 rm = list_entry(list.next, struct rds_message, m_sock_item);
 783                 list_del_init(&rm->m_sock_item);
 784                 rds_message_wait(rm);
 785
 786                 /* just in case the code above skipped this message
 787                  * because RDS_MSG_ON_CONN wasn't set, run it again here
 788                  * taking m_rs_lock is the only thing that keeps us
 789                  * from racing with ack processing.
 790                  */
 791                 spin_lock_irqsave(&rm->m_rs_lock, flags);
 792
 793                 spin_lock(&rs->rs_lock);
 794                 __rds_send_complete(rs, rm, RDS_RDMA_CANCELED);
 795                 spin_unlock(&rs->rs_lock);
 796
 797                 rm->m_rs = NULL;
 798                 spin_unlock_irqrestore(&rm->m_rs_lock, flags);
 799
 800                 rds_message_put(rm);
 801         }
 802 }
 803
 804 /*
 805  * we only want this to fire once so we use the callers 'queued'.  It's
 806  * possible that another thread can race with us and remove the
 807  * message from the flow with RDS_CANCEL_SENT_TO.
 808  */
 809 static int rds_send_queue_rm(struct rds_sock *rs, struct rds_connection *conn,
 810                              struct rds_message *rm, __be16 sport,
 811                              __be16 dport, int *queued)
 812 {
 813         unsigned long flags;
 814         u32 len;
 815
 816         if (*queued)
 817                 goto out;
 818
 819         len = be32_to_cpu(rm->m_inc.i_hdr.h_len);
 820
 821         /* this is the only place which holds both the socket's rs_lock
 822          * and the connection's c_lock */
 823         spin_lock_irqsave(&rs->rs_lock, flags);
 824
 825         /*
 826          * If there is a little space in sndbuf, we don't queue anything,
 827          * and userspace gets -EAGAIN. But poll() indicates there's send
 828          * room. This can lead to bad behavior (spinning) if snd_bytes isn't
 829          * freed up by incoming acks. So we check the *old* value of
 830          * rs_snd_bytes here to allow the last msg to exceed the buffer,
 831          * and poll() now knows no more data can be sent.
 832          */
 833         if (rs->rs_snd_bytes < rds_sk_sndbuf(rs)) {
 834                 rs->rs_snd_bytes += len;
 835
 836                 /* let recv side know we are close to send space exhaustion.
 837                  * This is probably not the optimal way to do it, as this
 838                  * means we set the flag on *all* messages as soon as our
 839                  * throughput hits a certain threshold.
 840                  */
 841                 if (rs->rs_snd_bytes >= rds_sk_sndbuf(rs) / 2)
 842                         __set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
 843
 844                 list_add_tail(&rm->m_sock_item, &rs->rs_send_queue);
 845                 set_bit(RDS_MSG_ON_SOCK, &rm->m_flags);
 846                 rds_message_addref(rm);
 847                 rm->m_rs = rs;
 848
 849                 /* The code ordering is a little weird, but we're
 850                    trying to minimize the time we hold c_lock */
 851                 rds_message_populate_header(&rm->m_inc.i_hdr, sport, dport, 0);
 852                 rm->m_inc.i_conn = conn;
 853                 rds_message_addref(rm);
 854
 855                 spin_lock(&conn->c_lock);
 856                 rm->m_inc.i_hdr.h_sequence = cpu_to_be64(conn->c_next_tx_seq++);
 857                 list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
 858                 set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
 859                 spin_unlock(&conn->c_lock);
 860
 861                 rdsdebug("queued msg %p len %d, rs %p bytes %d seq %llu\n",
 862                          rm, len, rs, rs->rs_snd_bytes,
 863                          (unsigned long long)be64_to_cpu(rm->m_inc.i_hdr.h_sequence));
 864
 865                 *queued = 1;
 866         }
 867
 868         spin_unlock_irqrestore(&rs->rs_lock, flags);
 869 out:
 870         return *queued;
 871 }
 872
 873 /*
 874  * rds_message is getting to be quite complicated, and we'd like to allocate
 875  * it all in one go. This figures out how big it needs to be up front.
 876  */
 877 static int rds_rm_size(struct msghdr *msg, int data_len)
 878 {
 879         struct cmsghdr *cmsg;
 880         int size = 0;
 881         int cmsg_groups = 0;
 882         int retval;
 883
 884         for_each_cmsghdr(cmsg, msg) {
 885                 if (!CMSG_OK(msg, cmsg))
 886                         return -EINVAL;
 887
 888                 if (cmsg->cmsg_level != SOL_RDS)
 889                         continue;
 890
 891                 switch (cmsg->cmsg_type) {
 892                 case RDS_CMSG_RDMA_ARGS:
 893                         cmsg_groups |= 1;
 894                         retval = rds_rdma_extra_size(CMSG_DATA(cmsg));
 895                         if (retval < 0)
 896                                 return retval;
 897                         size += retval;
 898
 899                         break;
 900
 901                 case RDS_CMSG_RDMA_DEST:
 902                 case RDS_CMSG_RDMA_MAP:
 903                         cmsg_groups |= 2;
 904                         /* these are valid but do no add any size */
 905                         break;
 906
 907                 case RDS_CMSG_ATOMIC_CSWP:
 908                 case RDS_CMSG_ATOMIC_FADD:
 909                 case RDS_CMSG_MASKED_ATOMIC_CSWP:
 910                 case RDS_CMSG_MASKED_ATOMIC_FADD:
 911                         cmsg_groups |= 1;
 912                         size += sizeof(struct scatterlist);
 913                         break;
 914
 915                 default:
 916                         return -EINVAL;
 917                 }
 918
 919         }
 920
 921         size += ceil(data_len, PAGE_SIZE) * sizeof(struct scatterlist);
 922
 923         /* Ensure (DEST, MAP) are never used with (ARGS, ATOMIC) */
 924         if (cmsg_groups == 3)
 925                 return -EINVAL;
 926
 927         return size;
 928 }
 929
 930 static int rds_cmsg_send(struct rds_sock *rs, struct rds_message *rm,
 931                          struct msghdr *msg, int *allocated_mr)
 932 {
 933         struct cmsghdr *cmsg;
 934         int ret = 0;
 935
 936         for_each_cmsghdr(cmsg, msg) {
 937                 if (!CMSG_OK(msg, cmsg))
 938                         return -EINVAL;
 939
 940                 if (cmsg->cmsg_level != SOL_RDS)
 941                         continue;
 942
 943                 /* As a side effect, RDMA_DEST and RDMA_MAP will set
 944                  * rm->rdma.m_rdma_cookie and rm->rdma.m_rdma_mr.
 945                  */
 946                 switch (cmsg->cmsg_type) {
 947                 case RDS_CMSG_RDMA_ARGS:
 948                         ret = rds_cmsg_rdma_args(rs, rm, cmsg);
 949                         break;
 950
 951                 case RDS_CMSG_RDMA_DEST:
 952                         ret = rds_cmsg_rdma_dest(rs, rm, cmsg);
 953                         break;
 954
 955                 case RDS_CMSG_RDMA_MAP:
 956                         ret = rds_cmsg_rdma_map(rs, rm, cmsg);
 957                         if (!ret)
 958                                 *allocated_mr = 1;
 959                         break;
 960                 case RDS_CMSG_ATOMIC_CSWP:
 961                 case RDS_CMSG_ATOMIC_FADD:
 962                 case RDS_CMSG_MASKED_ATOMIC_CSWP:
 963                 case RDS_CMSG_MASKED_ATOMIC_FADD:
 964                         ret = rds_cmsg_atomic(rs, rm, cmsg);
 965                         break;
 966
 967                 default:
 968                         return -EINVAL;
 969                 }
 970
 971                 if (ret)
 972                         break;
 973         }
 974
 975         return ret;
 976 }
 977
 978 int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
 979 {
 980         struct sock *sk = sock->sk;
 981         struct rds_sock *rs = rds_sk_to_rs(sk);
 982         DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
 983         __be32 daddr;
 984         __be16 dport;
 985         struct rds_message *rm = NULL;
 986         struct rds_connection *conn;
 987         int ret = 0;
 988         int queued = 0, allocated_mr = 0;
 989         int nonblock = msg->msg_flags & MSG_DONTWAIT;
 990         long timeo = sock_sndtimeo(sk, nonblock);
 991
 992         /* Mirror Linux UDP mirror of BSD error message compatibility */
 993         /* XXX: Perhaps MSG_MORE someday */
 994         if (msg->msg_flags & ~(MSG_DONTWAIT | MSG_CMSG_COMPAT)) {
 995                 ret = -EOPNOTSUPP;
 996                 goto out;
 997         }
 998
 999         if (msg->msg_namelen) {
1000                 /* XXX fail non-unicast destination IPs? */
1001                 if (msg->msg_namelen < sizeof(*usin) || usin->sin_family != AF_INET) {
1002                         ret = -EINVAL;
1003                         goto out;
1004                 }
1005                 daddr = usin->sin_addr.s_addr;
1006                 dport = usin->sin_port;
1007         } else {
1008                 /* We only care about consistency with ->connect() */
1009                 lock_sock(sk);
1010                 daddr = rs->rs_conn_addr;
1011                 dport = rs->rs_conn_port;
1012                 release_sock(sk);
1013         }
1014
1015         /* racing with another thread binding seems ok here */
1016         if (daddr == 0 || rs->rs_bound_addr == 0) {
1017                 ret = -ENOTCONN; /* XXX not a great errno */
1018                 goto out;
1019         }
1020
1021         if (payload_len > rds_sk_sndbuf(rs)) {
1022                 ret = -EMSGSIZE;
1023                 goto out;
1024         }
1025
1026         /* size of rm including all sgs */
1027         ret = rds_rm_size(msg, payload_len);
1028         if (ret < 0)
1029                 goto out;
1030
1031         rm = rds_message_alloc(ret, GFP_KERNEL);
1032         if (!rm) {
1033                 ret = -ENOMEM;
1034                 goto out;
1035         }
1036
1037         /* Attach data to the rm */
1038         if (payload_len) {
1039                 rm->data.op_sg = rds_message_alloc_sgs(rm, ceil(payload_len, PAGE_SIZE));
1040                 if (!rm->data.op_sg) {
1041                         ret = -ENOMEM;
1042                         goto out;
1043                 }
1044                 ret = rds_message_copy_from_user(rm, &msg->msg_iter);
1045                 if (ret)
1046                         goto out;
1047         }
1048         rm->data.op_active = 1;
1049
1050         rm->m_daddr = daddr;
1051
1052         /* rds_conn_create has a spinlock that runs with IRQ off.
1053          * Caching the conn in the socket helps a lot. */
1054         if (rs->rs_conn && rs->rs_conn->c_faddr == daddr)
1055                 conn = rs->rs_conn;
1056         else {
1057                 conn = rds_conn_create_outgoing(sock_net(sock->sk),
1058                                                 rs->rs_bound_addr, daddr,
1059                                         rs->rs_transport,
1060                                         sock->sk->sk_allocation);
1061                 if (IS_ERR(conn)) {
1062                         ret = PTR_ERR(conn);
1063                         goto out;
1064                 }
1065                 rs->rs_conn = conn;
1066         }
1067
1068         /* Parse any control messages the user may have included. */
1069         ret = rds_cmsg_send(rs, rm, msg, &allocated_mr);
1070         if (ret)
1071                 goto out;
1072
1073         if (rm->rdma.op_active && !conn->c_trans->xmit_rdma) {
1074                 printk_ratelimited(KERN_NOTICE "rdma_op %p conn xmit_rdma %p\n",
1075                                &rm->rdma, conn->c_trans->xmit_rdma);
1076                 ret = -EOPNOTSUPP;
1077                 goto out;
1078         }
1079
1080         if (rm->atomic.op_active && !conn->c_trans->xmit_atomic) {
1081                 printk_ratelimited(KERN_NOTICE "atomic_op %p conn xmit_atomic %p\n",
1082                                &rm->atomic, conn->c_trans->xmit_atomic);
1083                 ret = -EOPNOTSUPP;
1084                 goto out;
1085         }
1086
1087         rds_conn_connect_if_down(conn);
1088
1089         ret = rds_cong_wait(conn->c_fcong, dport, nonblock, rs);
1090         if (ret) {
1091                 rs->rs_seen_congestion = 1;
1092                 goto out;
1093         }
1094
1095         while (!rds_send_queue_rm(rs, conn, rm, rs->rs_bound_port,
1096                                   dport, &queued)) {
1097                 rds_stats_inc(s_send_queue_full);
1098
1099                 if (nonblock) {
1100                         ret = -EAGAIN;
1101                         goto out;
1102                 }
1103
1104                 timeo = wait_event_interruptible_timeout(*sk_sleep(sk),
1105                                         rds_send_queue_rm(rs, conn, rm,
1106                                                           rs->rs_bound_port,
1107                                                           dport,
1108                                                           &queued),
1109                                         timeo);
1110                 rdsdebug("sendmsg woke queued %d timeo %ld\n", queued, timeo);
1111                 if (timeo > 0 || timeo == MAX_SCHEDULE_TIMEOUT)
1112                         continue;
1113
1114                 ret = timeo;
1115                 if (ret == 0)
1116                         ret = -ETIMEDOUT;
1117                 goto out;
1118         }
1119
1120         /*
1121          * By now we've committed to the send.  We reuse rds_send_worker()
1122          * to retry sends in the rds thread if the transport asks us to.
1123          */
1124         rds_stats_inc(s_send_queued);
1125
1126         if (!test_bit(RDS_LL_SEND_FULL, &conn->c_flags))
1127                 rds_send_xmit(conn);
1128
1129         rds_message_put(rm);
1130         return payload_len;
1131
1132 out:
1133         /* If the user included a RDMA_MAP cmsg, we allocated a MR on the fly.
1134          * If the sendmsg goes through, we keep the MR. If it fails with EAGAIN
1135          * or in any other way, we need to destroy the MR again */
1136         if (allocated_mr)
1137                 rds_rdma_unuse(rs, rds_rdma_cookie_key(rm->m_rdma_cookie), 1);
1138
1139         if (rm)
1140                 rds_message_put(rm);
1141         return ret;
1142 }
1143
1144 /*
1145  * Reply to a ping packet.
1146  */
1147 int
1148 rds_send_pong(struct rds_connection *conn, __be16 dport)
1149 {
1150         struct rds_message *rm;
1151         unsigned long flags;
1152         int ret = 0;
1153
1154         rm = rds_message_alloc(0, GFP_ATOMIC);
1155         if (!rm) {
1156                 ret = -ENOMEM;
1157                 goto out;
1158         }
1159
1160         rm->m_daddr = conn->c_faddr;
1161         rm->data.op_active = 1;
1162
1163         rds_conn_connect_if_down(conn);
1164
1165         ret = rds_cong_wait(conn->c_fcong, dport, 1, NULL);
1166         if (ret)
1167                 goto out;
1168
1169         spin_lock_irqsave(&conn->c_lock, flags);
1170         list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
1171         set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
1172         rds_message_addref(rm);
1173         rm->m_inc.i_conn = conn;
1174
1175         rds_message_populate_header(&rm->m_inc.i_hdr, 0, dport,
1176                                     conn->c_next_tx_seq);
1177         conn->c_next_tx_seq++;
1178         spin_unlock_irqrestore(&conn->c_lock, flags);
1179
1180         rds_stats_inc(s_send_queued);
1181         rds_stats_inc(s_send_pong);
1182
1183         if (!test_bit(RDS_LL_SEND_FULL, &conn->c_flags))
1184                 queue_delayed_work(rds_wq, &conn->c_send_w, 0);
1185
1186         rds_message_put(rm);
1187         return 0;
1188
1189 out:
1190         if (rm)
1191                 rds_message_put(rm);
1192         return ret;
1193 }