linux/net/rds/iw_send.c
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   1/*
   2 * Copyright (c) 2006 Oracle.  All rights reserved.
   3 *
   4 * This software is available to you under a choice of one of two
   5 * licenses.  You may choose to be licensed under the terms of the GNU
   6 * General Public License (GPL) Version 2, available from the file
   7 * COPYING in the main directory of this source tree, or the
   8 * OpenIB.org BSD license below:
   9 *
  10 *     Redistribution and use in source and binary forms, with or
  11 *     without modification, are permitted provided that the following
  12 *     conditions are met:
  13 *
  14 *      - Redistributions of source code must retain the above
  15 *        copyright notice, this list of conditions and the following
  16 *        disclaimer.
  17 *
  18 *      - Redistributions in binary form must reproduce the above
  19 *        copyright notice, this list of conditions and the following
  20 *        disclaimer in the documentation and/or other materials
  21 *        provided with the distribution.
  22 *
  23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  30 * SOFTWARE.
  31 *
  32 */
  33#include <linux/kernel.h>
  34#include <linux/in.h>
  35#include <linux/device.h>
  36#include <linux/dmapool.h>
  37#include <linux/ratelimit.h>
  38
  39#include "rds.h"
  40#include "iw.h"
  41
  42static void rds_iw_send_rdma_complete(struct rds_message *rm,
  43                                      int wc_status)
  44{
  45        int notify_status;
  46
  47        switch (wc_status) {
  48        case IB_WC_WR_FLUSH_ERR:
  49                return;
  50
  51        case IB_WC_SUCCESS:
  52                notify_status = RDS_RDMA_SUCCESS;
  53                break;
  54
  55        case IB_WC_REM_ACCESS_ERR:
  56                notify_status = RDS_RDMA_REMOTE_ERROR;
  57                break;
  58
  59        default:
  60                notify_status = RDS_RDMA_OTHER_ERROR;
  61                break;
  62        }
  63        rds_rdma_send_complete(rm, notify_status);
  64}
  65
  66static void rds_iw_send_unmap_rdma(struct rds_iw_connection *ic,
  67                                   struct rm_rdma_op *op)
  68{
  69        if (op->op_mapped) {
  70                ib_dma_unmap_sg(ic->i_cm_id->device,
  71                        op->op_sg, op->op_nents,
  72                        op->op_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
  73                op->op_mapped = 0;
  74        }
  75}
  76
  77static void rds_iw_send_unmap_rm(struct rds_iw_connection *ic,
  78                          struct rds_iw_send_work *send,
  79                          int wc_status)
  80{
  81        struct rds_message *rm = send->s_rm;
  82
  83        rdsdebug("ic %p send %p rm %p\n", ic, send, rm);
  84
  85        ib_dma_unmap_sg(ic->i_cm_id->device,
  86                     rm->data.op_sg, rm->data.op_nents,
  87                     DMA_TO_DEVICE);
  88
  89        if (rm->rdma.op_active) {
  90                rds_iw_send_unmap_rdma(ic, &rm->rdma);
  91
  92                /* If the user asked for a completion notification on this
  93                 * message, we can implement three different semantics:
  94                 *  1.  Notify when we received the ACK on the RDS message
  95                 *      that was queued with the RDMA. This provides reliable
  96                 *      notification of RDMA status at the expense of a one-way
  97                 *      packet delay.
  98                 *  2.  Notify when the IB stack gives us the completion event for
  99                 *      the RDMA operation.
 100                 *  3.  Notify when the IB stack gives us the completion event for
 101                 *      the accompanying RDS messages.
 102                 * Here, we implement approach #3. To implement approach #2,
 103                 * call rds_rdma_send_complete from the cq_handler. To implement #1,
 104                 * don't call rds_rdma_send_complete at all, and fall back to the notify
 105                 * handling in the ACK processing code.
 106                 *
 107                 * Note: There's no need to explicitly sync any RDMA buffers using
 108                 * ib_dma_sync_sg_for_cpu - the completion for the RDMA
 109                 * operation itself unmapped the RDMA buffers, which takes care
 110                 * of synching.
 111                 */
 112                rds_iw_send_rdma_complete(rm, wc_status);
 113
 114                if (rm->rdma.op_write)
 115                        rds_stats_add(s_send_rdma_bytes, rm->rdma.op_bytes);
 116                else
 117                        rds_stats_add(s_recv_rdma_bytes, rm->rdma.op_bytes);
 118        }
 119
 120        /* If anyone waited for this message to get flushed out, wake
 121         * them up now */
 122        rds_message_unmapped(rm);
 123
 124        rds_message_put(rm);
 125        send->s_rm = NULL;
 126}
 127
 128void rds_iw_send_init_ring(struct rds_iw_connection *ic)
 129{
 130        struct rds_iw_send_work *send;
 131        u32 i;
 132
 133        for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
 134                struct ib_sge *sge;
 135
 136                send->s_rm = NULL;
 137                send->s_op = NULL;
 138                send->s_mapping = NULL;
 139
 140                send->s_wr.next = NULL;
 141                send->s_wr.wr_id = i;
 142                send->s_wr.sg_list = send->s_sge;
 143                send->s_wr.num_sge = 1;
 144                send->s_wr.opcode = IB_WR_SEND;
 145                send->s_wr.send_flags = 0;
 146                send->s_wr.ex.imm_data = 0;
 147
 148                sge = rds_iw_data_sge(ic, send->s_sge);
 149                sge->lkey = 0;
 150
 151                sge = rds_iw_header_sge(ic, send->s_sge);
 152                sge->addr = ic->i_send_hdrs_dma + (i * sizeof(struct rds_header));
 153                sge->length = sizeof(struct rds_header);
 154                sge->lkey = 0;
 155
 156                send->s_mr = ib_alloc_fast_reg_mr(ic->i_pd, fastreg_message_size);
 157                if (IS_ERR(send->s_mr)) {
 158                        printk(KERN_WARNING "RDS/IW: ib_alloc_fast_reg_mr failed\n");
 159                        break;
 160                }
 161
 162                send->s_page_list = ib_alloc_fast_reg_page_list(
 163                        ic->i_cm_id->device, fastreg_message_size);
 164                if (IS_ERR(send->s_page_list)) {
 165                        printk(KERN_WARNING "RDS/IW: ib_alloc_fast_reg_page_list failed\n");
 166                        break;
 167                }
 168        }
 169}
 170
 171void rds_iw_send_clear_ring(struct rds_iw_connection *ic)
 172{
 173        struct rds_iw_send_work *send;
 174        u32 i;
 175
 176        for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
 177                BUG_ON(!send->s_mr);
 178                ib_dereg_mr(send->s_mr);
 179                BUG_ON(!send->s_page_list);
 180                ib_free_fast_reg_page_list(send->s_page_list);
 181                if (send->s_wr.opcode == 0xdead)
 182                        continue;
 183                if (send->s_rm)
 184                        rds_iw_send_unmap_rm(ic, send, IB_WC_WR_FLUSH_ERR);
 185                if (send->s_op)
 186                        rds_iw_send_unmap_rdma(ic, send->s_op);
 187        }
 188}
 189
 190/*
 191 * The _oldest/_free ring operations here race cleanly with the alloc/unalloc
 192 * operations performed in the send path.  As the sender allocs and potentially
 193 * unallocs the next free entry in the ring it doesn't alter which is
 194 * the next to be freed, which is what this is concerned with.
 195 */
 196void rds_iw_send_cq_comp_handler(struct ib_cq *cq, void *context)
 197{
 198        struct rds_connection *conn = context;
 199        struct rds_iw_connection *ic = conn->c_transport_data;
 200        struct ib_wc wc;
 201        struct rds_iw_send_work *send;
 202        u32 completed;
 203        u32 oldest;
 204        u32 i;
 205        int ret;
 206
 207        rdsdebug("cq %p conn %p\n", cq, conn);
 208        rds_iw_stats_inc(s_iw_tx_cq_call);
 209        ret = ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
 210        if (ret)
 211                rdsdebug("ib_req_notify_cq send failed: %d\n", ret);
 212
 213        while (ib_poll_cq(cq, 1, &wc) > 0) {
 214                rdsdebug("wc wr_id 0x%llx status %u byte_len %u imm_data %u\n",
 215                         (unsigned long long)wc.wr_id, wc.status, wc.byte_len,
 216                         be32_to_cpu(wc.ex.imm_data));
 217                rds_iw_stats_inc(s_iw_tx_cq_event);
 218
 219                if (wc.status != IB_WC_SUCCESS) {
 220                        printk(KERN_ERR "WC Error:  status = %d opcode = %d\n", wc.status, wc.opcode);
 221                        break;
 222                }
 223
 224                if (wc.opcode == IB_WC_LOCAL_INV && wc.wr_id == RDS_IW_LOCAL_INV_WR_ID) {
 225                        ic->i_fastreg_posted = 0;
 226                        continue;
 227                }
 228
 229                if (wc.opcode == IB_WC_FAST_REG_MR && wc.wr_id == RDS_IW_FAST_REG_WR_ID) {
 230                        ic->i_fastreg_posted = 1;
 231                        continue;
 232                }
 233
 234                if (wc.wr_id == RDS_IW_ACK_WR_ID) {
 235                        if (ic->i_ack_queued + HZ/2 < jiffies)
 236                                rds_iw_stats_inc(s_iw_tx_stalled);
 237                        rds_iw_ack_send_complete(ic);
 238                        continue;
 239                }
 240
 241                oldest = rds_iw_ring_oldest(&ic->i_send_ring);
 242
 243                completed = rds_iw_ring_completed(&ic->i_send_ring, wc.wr_id, oldest);
 244
 245                for (i = 0; i < completed; i++) {
 246                        send = &ic->i_sends[oldest];
 247
 248                        /* In the error case, wc.opcode sometimes contains garbage */
 249                        switch (send->s_wr.opcode) {
 250                        case IB_WR_SEND:
 251                                if (send->s_rm)
 252                                        rds_iw_send_unmap_rm(ic, send, wc.status);
 253                                break;
 254                        case IB_WR_FAST_REG_MR:
 255                        case IB_WR_RDMA_WRITE:
 256                        case IB_WR_RDMA_READ:
 257                        case IB_WR_RDMA_READ_WITH_INV:
 258                                /* Nothing to be done - the SG list will be unmapped
 259                                 * when the SEND completes. */
 260                                break;
 261                        default:
 262                                printk_ratelimited(KERN_NOTICE
 263                                                "RDS/IW: %s: unexpected opcode 0x%x in WR!\n",
 264                                                __func__, send->s_wr.opcode);
 265                                break;
 266                        }
 267
 268                        send->s_wr.opcode = 0xdead;
 269                        send->s_wr.num_sge = 1;
 270                        if (send->s_queued + HZ/2 < jiffies)
 271                                rds_iw_stats_inc(s_iw_tx_stalled);
 272
 273                        /* If a RDMA operation produced an error, signal this right
 274                         * away. If we don't, the subsequent SEND that goes with this
 275                         * RDMA will be canceled with ERR_WFLUSH, and the application
 276                         * never learn that the RDMA failed. */
 277                        if (unlikely(wc.status == IB_WC_REM_ACCESS_ERR && send->s_op)) {
 278                                struct rds_message *rm;
 279
 280                                rm = rds_send_get_message(conn, send->s_op);
 281                                if (rm)
 282                                        rds_iw_send_rdma_complete(rm, wc.status);
 283                        }
 284
 285                        oldest = (oldest + 1) % ic->i_send_ring.w_nr;
 286                }
 287
 288                rds_iw_ring_free(&ic->i_send_ring, completed);
 289
 290                if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags) ||
 291                    test_bit(0, &conn->c_map_queued))
 292                        queue_delayed_work(rds_wq, &conn->c_send_w, 0);
 293
 294                /* We expect errors as the qp is drained during shutdown */
 295                if (wc.status != IB_WC_SUCCESS && rds_conn_up(conn)) {
 296                        rds_iw_conn_error(conn,
 297                                "send completion on %pI4 "
 298                                "had status %u, disconnecting and reconnecting\n",
 299                                &conn->c_faddr, wc.status);
 300                }
 301        }
 302}
 303
 304/*
 305 * This is the main function for allocating credits when sending
 306 * messages.
 307 *
 308 * Conceptually, we have two counters:
 309 *  -   send credits: this tells us how many WRs we're allowed
 310 *      to submit without overruning the receiver's queue. For
 311 *      each SEND WR we post, we decrement this by one.
 312 *
 313 *  -   posted credits: this tells us how many WRs we recently
 314 *      posted to the receive queue. This value is transferred
 315 *      to the peer as a "credit update" in a RDS header field.
 316 *      Every time we transmit credits to the peer, we subtract
 317 *      the amount of transferred credits from this counter.
 318 *
 319 * It is essential that we avoid situations where both sides have
 320 * exhausted their send credits, and are unable to send new credits
 321 * to the peer. We achieve this by requiring that we send at least
 322 * one credit update to the peer before exhausting our credits.
 323 * When new credits arrive, we subtract one credit that is withheld
 324 * until we've posted new buffers and are ready to transmit these
 325 * credits (see rds_iw_send_add_credits below).
 326 *
 327 * The RDS send code is essentially single-threaded; rds_send_xmit
 328 * grabs c_send_lock to ensure exclusive access to the send ring.
 329 * However, the ACK sending code is independent and can race with
 330 * message SENDs.
 331 *
 332 * In the send path, we need to update the counters for send credits
 333 * and the counter of posted buffers atomically - when we use the
 334 * last available credit, we cannot allow another thread to race us
 335 * and grab the posted credits counter.  Hence, we have to use a
 336 * spinlock to protect the credit counter, or use atomics.
 337 *
 338 * Spinlocks shared between the send and the receive path are bad,
 339 * because they create unnecessary delays. An early implementation
 340 * using a spinlock showed a 5% degradation in throughput at some
 341 * loads.
 342 *
 343 * This implementation avoids spinlocks completely, putting both
 344 * counters into a single atomic, and updating that atomic using
 345 * atomic_add (in the receive path, when receiving fresh credits),
 346 * and using atomic_cmpxchg when updating the two counters.
 347 */
 348int rds_iw_send_grab_credits(struct rds_iw_connection *ic,
 349                             u32 wanted, u32 *adv_credits, int need_posted, int max_posted)
 350{
 351        unsigned int avail, posted, got = 0, advertise;
 352        long oldval, newval;
 353
 354        *adv_credits = 0;
 355        if (!ic->i_flowctl)
 356                return wanted;
 357
 358try_again:
 359        advertise = 0;
 360        oldval = newval = atomic_read(&ic->i_credits);
 361        posted = IB_GET_POST_CREDITS(oldval);
 362        avail = IB_GET_SEND_CREDITS(oldval);
 363
 364        rdsdebug("rds_iw_send_grab_credits(%u): credits=%u posted=%u\n",
 365                        wanted, avail, posted);
 366
 367        /* The last credit must be used to send a credit update. */
 368        if (avail && !posted)
 369                avail--;
 370
 371        if (avail < wanted) {
 372                struct rds_connection *conn = ic->i_cm_id->context;
 373
 374                /* Oops, there aren't that many credits left! */
 375                set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
 376                got = avail;
 377        } else {
 378                /* Sometimes you get what you want, lalala. */
 379                got = wanted;
 380        }
 381        newval -= IB_SET_SEND_CREDITS(got);
 382
 383        /*
 384         * If need_posted is non-zero, then the caller wants
 385         * the posted regardless of whether any send credits are
 386         * available.
 387         */
 388        if (posted && (got || need_posted)) {
 389                advertise = min_t(unsigned int, posted, max_posted);
 390                newval -= IB_SET_POST_CREDITS(advertise);
 391        }
 392
 393        /* Finally bill everything */
 394        if (atomic_cmpxchg(&ic->i_credits, oldval, newval) != oldval)
 395                goto try_again;
 396
 397        *adv_credits = advertise;
 398        return got;
 399}
 400
 401void rds_iw_send_add_credits(struct rds_connection *conn, unsigned int credits)
 402{
 403        struct rds_iw_connection *ic = conn->c_transport_data;
 404
 405        if (credits == 0)
 406                return;
 407
 408        rdsdebug("rds_iw_send_add_credits(%u): current=%u%s\n",
 409                        credits,
 410                        IB_GET_SEND_CREDITS(atomic_read(&ic->i_credits)),
 411                        test_bit(RDS_LL_SEND_FULL, &conn->c_flags) ? ", ll_send_full" : "");
 412
 413        atomic_add(IB_SET_SEND_CREDITS(credits), &ic->i_credits);
 414        if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags))
 415                queue_delayed_work(rds_wq, &conn->c_send_w, 0);
 416
 417        WARN_ON(IB_GET_SEND_CREDITS(credits) >= 16384);
 418
 419        rds_iw_stats_inc(s_iw_rx_credit_updates);
 420}
 421
 422void rds_iw_advertise_credits(struct rds_connection *conn, unsigned int posted)
 423{
 424        struct rds_iw_connection *ic = conn->c_transport_data;
 425
 426        if (posted == 0)
 427                return;
 428
 429        atomic_add(IB_SET_POST_CREDITS(posted), &ic->i_credits);
 430
 431        /* Decide whether to send an update to the peer now.
 432         * If we would send a credit update for every single buffer we
 433         * post, we would end up with an ACK storm (ACK arrives,
 434         * consumes buffer, we refill the ring, send ACK to remote
 435         * advertising the newly posted buffer... ad inf)
 436         *
 437         * Performance pretty much depends on how often we send
 438         * credit updates - too frequent updates mean lots of ACKs.
 439         * Too infrequent updates, and the peer will run out of
 440         * credits and has to throttle.
 441         * For the time being, 16 seems to be a good compromise.
 442         */
 443        if (IB_GET_POST_CREDITS(atomic_read(&ic->i_credits)) >= 16)
 444                set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
 445}
 446
 447static inline void
 448rds_iw_xmit_populate_wr(struct rds_iw_connection *ic,
 449                struct rds_iw_send_work *send, unsigned int pos,
 450                unsigned long buffer, unsigned int length,
 451                int send_flags)
 452{
 453        struct ib_sge *sge;
 454
 455        WARN_ON(pos != send - ic->i_sends);
 456
 457        send->s_wr.send_flags = send_flags;
 458        send->s_wr.opcode = IB_WR_SEND;
 459        send->s_wr.num_sge = 2;
 460        send->s_wr.next = NULL;
 461        send->s_queued = jiffies;
 462        send->s_op = NULL;
 463
 464        if (length != 0) {
 465                sge = rds_iw_data_sge(ic, send->s_sge);
 466                sge->addr = buffer;
 467                sge->length = length;
 468                sge->lkey = rds_iw_local_dma_lkey(ic);
 469
 470                sge = rds_iw_header_sge(ic, send->s_sge);
 471        } else {
 472                /* We're sending a packet with no payload. There is only
 473                 * one SGE */
 474                send->s_wr.num_sge = 1;
 475                sge = &send->s_sge[0];
 476        }
 477
 478        sge->addr = ic->i_send_hdrs_dma + (pos * sizeof(struct rds_header));
 479        sge->length = sizeof(struct rds_header);
 480        sge->lkey = rds_iw_local_dma_lkey(ic);
 481}
 482
 483/*
 484 * This can be called multiple times for a given message.  The first time
 485 * we see a message we map its scatterlist into the IB device so that
 486 * we can provide that mapped address to the IB scatter gather entries
 487 * in the IB work requests.  We translate the scatterlist into a series
 488 * of work requests that fragment the message.  These work requests complete
 489 * in order so we pass ownership of the message to the completion handler
 490 * once we send the final fragment.
 491 *
 492 * The RDS core uses the c_send_lock to only enter this function once
 493 * per connection.  This makes sure that the tx ring alloc/unalloc pairs
 494 * don't get out of sync and confuse the ring.
 495 */
 496int rds_iw_xmit(struct rds_connection *conn, struct rds_message *rm,
 497                unsigned int hdr_off, unsigned int sg, unsigned int off)
 498{
 499        struct rds_iw_connection *ic = conn->c_transport_data;
 500        struct ib_device *dev = ic->i_cm_id->device;
 501        struct rds_iw_send_work *send = NULL;
 502        struct rds_iw_send_work *first;
 503        struct rds_iw_send_work *prev;
 504        struct ib_send_wr *failed_wr;
 505        struct scatterlist *scat;
 506        u32 pos;
 507        u32 i;
 508        u32 work_alloc;
 509        u32 credit_alloc;
 510        u32 posted;
 511        u32 adv_credits = 0;
 512        int send_flags = 0;
 513        int sent;
 514        int ret;
 515        int flow_controlled = 0;
 516
 517        BUG_ON(off % RDS_FRAG_SIZE);
 518        BUG_ON(hdr_off != 0 && hdr_off != sizeof(struct rds_header));
 519
 520        /* Fastreg support */
 521        if (rds_rdma_cookie_key(rm->m_rdma_cookie) && !ic->i_fastreg_posted) {
 522                ret = -EAGAIN;
 523                goto out;
 524        }
 525
 526        /* FIXME we may overallocate here */
 527        if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0)
 528                i = 1;
 529        else
 530                i = ceil(be32_to_cpu(rm->m_inc.i_hdr.h_len), RDS_FRAG_SIZE);
 531
 532        work_alloc = rds_iw_ring_alloc(&ic->i_send_ring, i, &pos);
 533        if (work_alloc == 0) {
 534                set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
 535                rds_iw_stats_inc(s_iw_tx_ring_full);
 536                ret = -ENOMEM;
 537                goto out;
 538        }
 539
 540        credit_alloc = work_alloc;
 541        if (ic->i_flowctl) {
 542                credit_alloc = rds_iw_send_grab_credits(ic, work_alloc, &posted, 0, RDS_MAX_ADV_CREDIT);
 543                adv_credits += posted;
 544                if (credit_alloc < work_alloc) {
 545                        rds_iw_ring_unalloc(&ic->i_send_ring, work_alloc - credit_alloc);
 546                        work_alloc = credit_alloc;
 547                        flow_controlled++;
 548                }
 549                if (work_alloc == 0) {
 550                        set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
 551                        rds_iw_stats_inc(s_iw_tx_throttle);
 552                        ret = -ENOMEM;
 553                        goto out;
 554                }
 555        }
 556
 557        /* map the message the first time we see it */
 558        if (!ic->i_rm) {
 559                /*
 560                printk(KERN_NOTICE "rds_iw_xmit prep msg dport=%u flags=0x%x len=%d\n",
 561                                be16_to_cpu(rm->m_inc.i_hdr.h_dport),
 562                                rm->m_inc.i_hdr.h_flags,
 563                                be32_to_cpu(rm->m_inc.i_hdr.h_len));
 564                   */
 565                if (rm->data.op_nents) {
 566                        rm->data.op_count = ib_dma_map_sg(dev,
 567                                                          rm->data.op_sg,
 568                                                          rm->data.op_nents,
 569                                                          DMA_TO_DEVICE);
 570                        rdsdebug("ic %p mapping rm %p: %d\n", ic, rm, rm->data.op_count);
 571                        if (rm->data.op_count == 0) {
 572                                rds_iw_stats_inc(s_iw_tx_sg_mapping_failure);
 573                                rds_iw_ring_unalloc(&ic->i_send_ring, work_alloc);
 574                                ret = -ENOMEM; /* XXX ? */
 575                                goto out;
 576                        }
 577                } else {
 578                        rm->data.op_count = 0;
 579                }
 580
 581                ic->i_unsignaled_wrs = rds_iw_sysctl_max_unsig_wrs;
 582                ic->i_unsignaled_bytes = rds_iw_sysctl_max_unsig_bytes;
 583                rds_message_addref(rm);
 584                ic->i_rm = rm;
 585
 586                /* Finalize the header */
 587                if (test_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags))
 588                        rm->m_inc.i_hdr.h_flags |= RDS_FLAG_ACK_REQUIRED;
 589                if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags))
 590                        rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED;
 591
 592                /* If it has a RDMA op, tell the peer we did it. This is
 593                 * used by the peer to release use-once RDMA MRs. */
 594                if (rm->rdma.op_active) {
 595                        struct rds_ext_header_rdma ext_hdr;
 596
 597                        ext_hdr.h_rdma_rkey = cpu_to_be32(rm->rdma.op_rkey);
 598                        rds_message_add_extension(&rm->m_inc.i_hdr,
 599                                        RDS_EXTHDR_RDMA, &ext_hdr, sizeof(ext_hdr));
 600                }
 601                if (rm->m_rdma_cookie) {
 602                        rds_message_add_rdma_dest_extension(&rm->m_inc.i_hdr,
 603                                        rds_rdma_cookie_key(rm->m_rdma_cookie),
 604                                        rds_rdma_cookie_offset(rm->m_rdma_cookie));
 605                }
 606
 607                /* Note - rds_iw_piggyb_ack clears the ACK_REQUIRED bit, so
 608                 * we should not do this unless we have a chance of at least
 609                 * sticking the header into the send ring. Which is why we
 610                 * should call rds_iw_ring_alloc first. */
 611                rm->m_inc.i_hdr.h_ack = cpu_to_be64(rds_iw_piggyb_ack(ic));
 612                rds_message_make_checksum(&rm->m_inc.i_hdr);
 613
 614                /*
 615                 * Update adv_credits since we reset the ACK_REQUIRED bit.
 616                 */
 617                rds_iw_send_grab_credits(ic, 0, &posted, 1, RDS_MAX_ADV_CREDIT - adv_credits);
 618                adv_credits += posted;
 619                BUG_ON(adv_credits > 255);
 620        }
 621
 622        send = &ic->i_sends[pos];
 623        first = send;
 624        prev = NULL;
 625        scat = &rm->data.op_sg[sg];
 626        sent = 0;
 627        i = 0;
 628
 629        /* Sometimes you want to put a fence between an RDMA
 630         * READ and the following SEND.
 631         * We could either do this all the time
 632         * or when requested by the user. Right now, we let
 633         * the application choose.
 634         */
 635        if (rm->rdma.op_active && rm->rdma.op_fence)
 636                send_flags = IB_SEND_FENCE;
 637
 638        /*
 639         * We could be copying the header into the unused tail of the page.
 640         * That would need to be changed in the future when those pages might
 641         * be mapped userspace pages or page cache pages.  So instead we always
 642         * use a second sge and our long-lived ring of mapped headers.  We send
 643         * the header after the data so that the data payload can be aligned on
 644         * the receiver.
 645         */
 646
 647        /* handle a 0-len message */
 648        if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0) {
 649                rds_iw_xmit_populate_wr(ic, send, pos, 0, 0, send_flags);
 650                goto add_header;
 651        }
 652
 653        /* if there's data reference it with a chain of work reqs */
 654        for (; i < work_alloc && scat != &rm->data.op_sg[rm->data.op_count]; i++) {
 655                unsigned int len;
 656
 657                send = &ic->i_sends[pos];
 658
 659                len = min(RDS_FRAG_SIZE, ib_sg_dma_len(dev, scat) - off);
 660                rds_iw_xmit_populate_wr(ic, send, pos,
 661                                ib_sg_dma_address(dev, scat) + off, len,
 662                                send_flags);
 663
 664                /*
 665                 * We want to delay signaling completions just enough to get
 666                 * the batching benefits but not so much that we create dead time
 667                 * on the wire.
 668                 */
 669                if (ic->i_unsignaled_wrs-- == 0) {
 670                        ic->i_unsignaled_wrs = rds_iw_sysctl_max_unsig_wrs;
 671                        send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
 672                }
 673
 674                ic->i_unsignaled_bytes -= len;
 675                if (ic->i_unsignaled_bytes <= 0) {
 676                        ic->i_unsignaled_bytes = rds_iw_sysctl_max_unsig_bytes;
 677                        send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
 678                }
 679
 680                /*
 681                 * Always signal the last one if we're stopping due to flow control.
 682                 */
 683                if (flow_controlled && i == (work_alloc-1))
 684                        send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
 685
 686                rdsdebug("send %p wr %p num_sge %u next %p\n", send,
 687                         &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
 688
 689                sent += len;
 690                off += len;
 691                if (off == ib_sg_dma_len(dev, scat)) {
 692                        scat++;
 693                        off = 0;
 694                }
 695
 696add_header:
 697                /* Tack on the header after the data. The header SGE should already
 698                 * have been set up to point to the right header buffer. */
 699                memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header));
 700
 701                if (0) {
 702                        struct rds_header *hdr = &ic->i_send_hdrs[pos];
 703
 704                        printk(KERN_NOTICE "send WR dport=%u flags=0x%x len=%d\n",
 705                                be16_to_cpu(hdr->h_dport),
 706                                hdr->h_flags,
 707                                be32_to_cpu(hdr->h_len));
 708                }
 709                if (adv_credits) {
 710                        struct rds_header *hdr = &ic->i_send_hdrs[pos];
 711
 712                        /* add credit and redo the header checksum */
 713                        hdr->h_credit = adv_credits;
 714                        rds_message_make_checksum(hdr);
 715                        adv_credits = 0;
 716                        rds_iw_stats_inc(s_iw_tx_credit_updates);
 717                }
 718
 719                if (prev)
 720                        prev->s_wr.next = &send->s_wr;
 721                prev = send;
 722
 723                pos = (pos + 1) % ic->i_send_ring.w_nr;
 724        }
 725
 726        /* Account the RDS header in the number of bytes we sent, but just once.
 727         * The caller has no concept of fragmentation. */
 728        if (hdr_off == 0)
 729                sent += sizeof(struct rds_header);
 730
 731        /* if we finished the message then send completion owns it */
 732        if (scat == &rm->data.op_sg[rm->data.op_count]) {
 733                prev->s_rm = ic->i_rm;
 734                prev->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
 735                ic->i_rm = NULL;
 736        }
 737
 738        if (i < work_alloc) {
 739                rds_iw_ring_unalloc(&ic->i_send_ring, work_alloc - i);
 740                work_alloc = i;
 741        }
 742        if (ic->i_flowctl && i < credit_alloc)
 743                rds_iw_send_add_credits(conn, credit_alloc - i);
 744
 745        /* XXX need to worry about failed_wr and partial sends. */
 746        failed_wr = &first->s_wr;
 747        ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
 748        rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
 749                 first, &first->s_wr, ret, failed_wr);
 750        BUG_ON(failed_wr != &first->s_wr);
 751        if (ret) {
 752                printk(KERN_WARNING "RDS/IW: ib_post_send to %pI4 "
 753                       "returned %d\n", &conn->c_faddr, ret);
 754                rds_iw_ring_unalloc(&ic->i_send_ring, work_alloc);
 755                if (prev->s_rm) {
 756                        ic->i_rm = prev->s_rm;
 757                        prev->s_rm = NULL;
 758                }
 759                goto out;
 760        }
 761
 762        ret = sent;
 763out:
 764        BUG_ON(adv_credits);
 765        return ret;
 766}
 767
 768static void rds_iw_build_send_fastreg(struct rds_iw_device *rds_iwdev, struct rds_iw_connection *ic, struct rds_iw_send_work *send, int nent, int len, u64 sg_addr)
 769{
 770        BUG_ON(nent > send->s_page_list->max_page_list_len);
 771        /*
 772         * Perform a WR for the fast_reg_mr. Each individual page
 773         * in the sg list is added to the fast reg page list and placed
 774         * inside the fast_reg_mr WR.
 775         */
 776        send->s_wr.opcode = IB_WR_FAST_REG_MR;
 777        send->s_wr.wr.fast_reg.length = len;
 778        send->s_wr.wr.fast_reg.rkey = send->s_mr->rkey;
 779        send->s_wr.wr.fast_reg.page_list = send->s_page_list;
 780        send->s_wr.wr.fast_reg.page_list_len = nent;
 781        send->s_wr.wr.fast_reg.page_shift = PAGE_SHIFT;
 782        send->s_wr.wr.fast_reg.access_flags = IB_ACCESS_REMOTE_WRITE;
 783        send->s_wr.wr.fast_reg.iova_start = sg_addr;
 784
 785        ib_update_fast_reg_key(send->s_mr, send->s_remap_count++);
 786}
 787
 788int rds_iw_xmit_rdma(struct rds_connection *conn, struct rm_rdma_op *op)
 789{
 790        struct rds_iw_connection *ic = conn->c_transport_data;
 791        struct rds_iw_send_work *send = NULL;
 792        struct rds_iw_send_work *first;
 793        struct rds_iw_send_work *prev;
 794        struct ib_send_wr *failed_wr;
 795        struct rds_iw_device *rds_iwdev;
 796        struct scatterlist *scat;
 797        unsigned long len;
 798        u64 remote_addr = op->op_remote_addr;
 799        u32 pos, fr_pos;
 800        u32 work_alloc;
 801        u32 i;
 802        u32 j;
 803        int sent;
 804        int ret;
 805        int num_sge;
 806
 807        rds_iwdev = ib_get_client_data(ic->i_cm_id->device, &rds_iw_client);
 808
 809        /* map the message the first time we see it */
 810        if (!op->op_mapped) {
 811                op->op_count = ib_dma_map_sg(ic->i_cm_id->device,
 812                                             op->op_sg, op->op_nents, (op->op_write) ?
 813                                             DMA_TO_DEVICE : DMA_FROM_DEVICE);
 814                rdsdebug("ic %p mapping op %p: %d\n", ic, op, op->op_count);
 815                if (op->op_count == 0) {
 816                        rds_iw_stats_inc(s_iw_tx_sg_mapping_failure);
 817                        ret = -ENOMEM; /* XXX ? */
 818                        goto out;
 819                }
 820
 821                op->op_mapped = 1;
 822        }
 823
 824        if (!op->op_write) {
 825                /* Alloc space on the send queue for the fastreg */
 826                work_alloc = rds_iw_ring_alloc(&ic->i_send_ring, 1, &fr_pos);
 827                if (work_alloc != 1) {
 828                        rds_iw_ring_unalloc(&ic->i_send_ring, work_alloc);
 829                        rds_iw_stats_inc(s_iw_tx_ring_full);
 830                        ret = -ENOMEM;
 831                        goto out;
 832                }
 833        }
 834
 835        /*
 836         * Instead of knowing how to return a partial rdma read/write we insist that there
 837         * be enough work requests to send the entire message.
 838         */
 839        i = ceil(op->op_count, rds_iwdev->max_sge);
 840
 841        work_alloc = rds_iw_ring_alloc(&ic->i_send_ring, i, &pos);
 842        if (work_alloc != i) {
 843                rds_iw_ring_unalloc(&ic->i_send_ring, work_alloc);
 844                rds_iw_stats_inc(s_iw_tx_ring_full);
 845                ret = -ENOMEM;
 846                goto out;
 847        }
 848
 849        send = &ic->i_sends[pos];
 850        if (!op->op_write) {
 851                first = prev = &ic->i_sends[fr_pos];
 852        } else {
 853                first = send;
 854                prev = NULL;
 855        }
 856        scat = &op->op_sg[0];
 857        sent = 0;
 858        num_sge = op->op_count;
 859
 860        for (i = 0; i < work_alloc && scat != &op->op_sg[op->op_count]; i++) {
 861                send->s_wr.send_flags = 0;
 862                send->s_queued = jiffies;
 863
 864                /*
 865                 * We want to delay signaling completions just enough to get
 866                 * the batching benefits but not so much that we create dead time on the wire.
 867                 */
 868                if (ic->i_unsignaled_wrs-- == 0) {
 869                        ic->i_unsignaled_wrs = rds_iw_sysctl_max_unsig_wrs;
 870                        send->s_wr.send_flags = IB_SEND_SIGNALED;
 871                }
 872
 873                /* To avoid the need to have the plumbing to invalidate the fastreg_mr used
 874                 * for local access after RDS is finished with it, using
 875                 * IB_WR_RDMA_READ_WITH_INV will invalidate it after the read has completed.
 876                 */
 877                if (op->op_write)
 878                        send->s_wr.opcode = IB_WR_RDMA_WRITE;
 879                else
 880                        send->s_wr.opcode = IB_WR_RDMA_READ_WITH_INV;
 881
 882                send->s_wr.wr.rdma.remote_addr = remote_addr;
 883                send->s_wr.wr.rdma.rkey = op->op_rkey;
 884                send->s_op = op;
 885
 886                if (num_sge > rds_iwdev->max_sge) {
 887                        send->s_wr.num_sge = rds_iwdev->max_sge;
 888                        num_sge -= rds_iwdev->max_sge;
 889                } else
 890                        send->s_wr.num_sge = num_sge;
 891
 892                send->s_wr.next = NULL;
 893
 894                if (prev)
 895                        prev->s_wr.next = &send->s_wr;
 896
 897                for (j = 0; j < send->s_wr.num_sge && scat != &op->op_sg[op->op_count]; j++) {
 898                        len = ib_sg_dma_len(ic->i_cm_id->device, scat);
 899
 900                        if (send->s_wr.opcode == IB_WR_RDMA_READ_WITH_INV)
 901                                send->s_page_list->page_list[j] = ib_sg_dma_address(ic->i_cm_id->device, scat);
 902                        else {
 903                                send->s_sge[j].addr = ib_sg_dma_address(ic->i_cm_id->device, scat);
 904                                send->s_sge[j].length = len;
 905                                send->s_sge[j].lkey = rds_iw_local_dma_lkey(ic);
 906                        }
 907
 908                        sent += len;
 909                        rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr);
 910                        remote_addr += len;
 911
 912                        scat++;
 913                }
 914
 915                if (send->s_wr.opcode == IB_WR_RDMA_READ_WITH_INV) {
 916                        send->s_wr.num_sge = 1;
 917                        send->s_sge[0].addr = conn->c_xmit_rm->m_rs->rs_user_addr;
 918                        send->s_sge[0].length = conn->c_xmit_rm->m_rs->rs_user_bytes;
 919                        send->s_sge[0].lkey = ic->i_sends[fr_pos].s_mr->lkey;
 920                }
 921
 922                rdsdebug("send %p wr %p num_sge %u next %p\n", send,
 923                        &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
 924
 925                prev = send;
 926                if (++send == &ic->i_sends[ic->i_send_ring.w_nr])
 927                        send = ic->i_sends;
 928        }
 929
 930        /* if we finished the message then send completion owns it */
 931        if (scat == &op->op_sg[op->op_count])
 932                first->s_wr.send_flags = IB_SEND_SIGNALED;
 933
 934        if (i < work_alloc) {
 935                rds_iw_ring_unalloc(&ic->i_send_ring, work_alloc - i);
 936                work_alloc = i;
 937        }
 938
 939        /* On iWARP, local memory access by a remote system (ie, RDMA Read) is not
 940         * recommended.  Putting the lkey on the wire is a security hole, as it can
 941         * allow for memory access to all of memory on the remote system.  Some
 942         * adapters do not allow using the lkey for this at all.  To bypass this use a
 943         * fastreg_mr (or possibly a dma_mr)
 944         */
 945        if (!op->op_write) {
 946                rds_iw_build_send_fastreg(rds_iwdev, ic, &ic->i_sends[fr_pos],
 947                        op->op_count, sent, conn->c_xmit_rm->m_rs->rs_user_addr);
 948                work_alloc++;
 949        }
 950
 951        failed_wr = &first->s_wr;
 952        ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
 953        rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
 954                 first, &first->s_wr, ret, failed_wr);
 955        BUG_ON(failed_wr != &first->s_wr);
 956        if (ret) {
 957                printk(KERN_WARNING "RDS/IW: rdma ib_post_send to %pI4 "
 958                       "returned %d\n", &conn->c_faddr, ret);
 959                rds_iw_ring_unalloc(&ic->i_send_ring, work_alloc);
 960                goto out;
 961        }
 962
 963out:
 964        return ret;
 965}
 966
 967void rds_iw_xmit_complete(struct rds_connection *conn)
 968{
 969        struct rds_iw_connection *ic = conn->c_transport_data;
 970
 971        /* We may have a pending ACK or window update we were unable
 972         * to send previously (due to flow control). Try again. */
 973        rds_iw_attempt_ack(ic);
 974}
 975
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