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   1 /*
   2  * Copyright (c) 2005-2007 Network Appliance, Inc. 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 BSD-type
   8  * license below:
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  *
  14  *      Redistributions of source code must retain the above copyright
  15  *      notice, this list of conditions and the following disclaimer.
  16  *
  17  *      Redistributions in binary form must reproduce the above
  18  *      copyright notice, this list of conditions and the following
  19  *      disclaimer in the documentation and/or other materials provided
  20  *      with the distribution.
  21  *
  22  *      Neither the name of the Network Appliance, Inc. nor the names of
  23  *      its contributors may be used to endorse or promote products
  24  *      derived from this software without specific prior written
  25  *      permission.
  26  *
  27  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  30  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  31  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  32  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  33  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  34  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  35  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  36  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  37  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  38  *
  39  * Author: Tom Tucker <tom@opengridcomputing.com>
  40  */
  41
  42 #include <linux/sunrpc/svc_xprt.h>
  43 #include <linux/sunrpc/debug.h>
  44 #include <linux/sunrpc/rpc_rdma.h>
  45 #include <linux/spinlock.h>
  46 #include <rdma/ib_verbs.h>
  47 #include <rdma/rdma_cm.h>
  48 #include <linux/sunrpc/svc_rdma.h>
  49
  50 #define RPCDBG_FACILITY RPCDBG_SVCXPRT
  51
  52 static struct svc_xprt *svc_rdma_create(struct svc_serv *serv,
  53                                         struct sockaddr *sa, int salen,
  54                                         int flags);
  55 static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt);
  56 static void svc_rdma_release_rqst(struct svc_rqst *);
  57 static void dto_tasklet_func(unsigned long data);
  58 static void svc_rdma_detach(struct svc_xprt *xprt);
  59 static void svc_rdma_free(struct svc_xprt *xprt);
  60 static int svc_rdma_has_wspace(struct svc_xprt *xprt);
  61 static void rq_cq_reap(struct svcxprt_rdma *xprt);
  62 static void sq_cq_reap(struct svcxprt_rdma *xprt);
  63
  64 DECLARE_TASKLET(dto_tasklet, dto_tasklet_func, 0UL);
  65 static DEFINE_SPINLOCK(dto_lock);
  66 static LIST_HEAD(dto_xprt_q);
  67
  68 static struct svc_xprt_ops svc_rdma_ops = {
  69         .xpo_create = svc_rdma_create,
  70         .xpo_recvfrom = svc_rdma_recvfrom,
  71         .xpo_sendto = svc_rdma_sendto,
  72         .xpo_release_rqst = svc_rdma_release_rqst,
  73         .xpo_detach = svc_rdma_detach,
  74         .xpo_free = svc_rdma_free,
  75         .xpo_prep_reply_hdr = svc_rdma_prep_reply_hdr,
  76         .xpo_has_wspace = svc_rdma_has_wspace,
  77         .xpo_accept = svc_rdma_accept,
  78 };
  79
  80 struct svc_xprt_class svc_rdma_class = {
  81         .xcl_name = "rdma",
  82         .xcl_owner = THIS_MODULE,
  83         .xcl_ops = &svc_rdma_ops,
  84         .xcl_max_payload = RPCSVC_MAXPAYLOAD_TCP,
  85 };
  86
  87 static int rdma_bump_context_cache(struct svcxprt_rdma *xprt)
  88 {
  89         int target;
  90         int at_least_one = 0;
  91         struct svc_rdma_op_ctxt *ctxt;
  92
  93         target = min(xprt->sc_ctxt_cnt + xprt->sc_ctxt_bump,
  94                      xprt->sc_ctxt_max);
  95
  96         spin_lock_bh(&xprt->sc_ctxt_lock);
  97         while (xprt->sc_ctxt_cnt < target) {
  98                 xprt->sc_ctxt_cnt++;
  99                 spin_unlock_bh(&xprt->sc_ctxt_lock);
 100
 101                 ctxt = kmalloc(sizeof(*ctxt), GFP_KERNEL);
 102
 103                 spin_lock_bh(&xprt->sc_ctxt_lock);
 104                 if (ctxt) {
 105                         at_least_one = 1;
 106                         INIT_LIST_HEAD(&ctxt->free_list);
 107                         list_add(&ctxt->free_list, &xprt->sc_ctxt_free);
 108                 } else {
 109                         /* kmalloc failed...give up for now */
 110                         xprt->sc_ctxt_cnt--;
 111                         break;
 112                 }
 113         }
 114         spin_unlock_bh(&xprt->sc_ctxt_lock);
 115         dprintk("svcrdma: sc_ctxt_max=%d, sc_ctxt_cnt=%d\n",
 116                 xprt->sc_ctxt_max, xprt->sc_ctxt_cnt);
 117         return at_least_one;
 118 }
 119
 120 struct svc_rdma_op_ctxt *svc_rdma_get_context(struct svcxprt_rdma *xprt)
 121 {
 122         struct svc_rdma_op_ctxt *ctxt;
 123
 124         while (1) {
 125                 spin_lock_bh(&xprt->sc_ctxt_lock);
 126                 if (unlikely(list_empty(&xprt->sc_ctxt_free))) {
 127                         /* Try to bump my cache. */
 128                         spin_unlock_bh(&xprt->sc_ctxt_lock);
 129
 130                         if (rdma_bump_context_cache(xprt))
 131                                 continue;
 132
 133                         printk(KERN_INFO "svcrdma: sleeping waiting for "
 134                                "context memory on xprt=%p\n",
 135                                xprt);
 136                         schedule_timeout_uninterruptible(msecs_to_jiffies(500));
 137                         continue;
 138                 }
 139                 ctxt = list_entry(xprt->sc_ctxt_free.next,
 140                                   struct svc_rdma_op_ctxt,
 141                                   free_list);
 142                 list_del_init(&ctxt->free_list);
 143                 spin_unlock_bh(&xprt->sc_ctxt_lock);
 144                 ctxt->xprt = xprt;
 145                 INIT_LIST_HEAD(&ctxt->dto_q);
 146                 ctxt->count = 0;
 147                 atomic_inc(&xprt->sc_ctxt_used);
 148                 break;
 149         }
 150         return ctxt;
 151 }
 152
 153 void svc_rdma_put_context(struct svc_rdma_op_ctxt *ctxt, int free_pages)
 154 {
 155         struct svcxprt_rdma *xprt;
 156         int i;
 157
 158         BUG_ON(!ctxt);
 159         xprt = ctxt->xprt;
 160         if (free_pages)
 161                 for (i = 0; i < ctxt->count; i++)
 162                         put_page(ctxt->pages[i]);
 163
 164         for (i = 0; i < ctxt->count; i++)
 165                 dma_unmap_single(xprt->sc_cm_id->device->dma_device,
 166                                  ctxt->sge[i].addr,
 167                                  ctxt->sge[i].length,
 168                                  ctxt->direction);
 169
 170         spin_lock_bh(&xprt->sc_ctxt_lock);
 171         list_add(&ctxt->free_list, &xprt->sc_ctxt_free);
 172         spin_unlock_bh(&xprt->sc_ctxt_lock);
 173         atomic_dec(&xprt->sc_ctxt_used);
 174 }
 175
 176 /* ib_cq event handler */
 177 static void cq_event_handler(struct ib_event *event, void *context)
 178 {
 179         struct svc_xprt *xprt = context;
 180         dprintk("svcrdma: received CQ event id=%d, context=%p\n",
 181                 event->event, context);
 182         set_bit(XPT_CLOSE, &xprt->xpt_flags);
 183 }
 184
 185 /* QP event handler */
 186 static void qp_event_handler(struct ib_event *event, void *context)
 187 {
 188         struct svc_xprt *xprt = context;
 189
 190         switch (event->event) {
 191         /* These are considered benign events */
 192         case IB_EVENT_PATH_MIG:
 193         case IB_EVENT_COMM_EST:
 194         case IB_EVENT_SQ_DRAINED:
 195         case IB_EVENT_QP_LAST_WQE_REACHED:
 196                 dprintk("svcrdma: QP event %d received for QP=%p\n",
 197                         event->event, event->element.qp);
 198                 break;
 199         /* These are considered fatal events */
 200         case IB_EVENT_PATH_MIG_ERR:
 201         case IB_EVENT_QP_FATAL:
 202         case IB_EVENT_QP_REQ_ERR:
 203         case IB_EVENT_QP_ACCESS_ERR:
 204         case IB_EVENT_DEVICE_FATAL:
 205         default:
 206                 dprintk("svcrdma: QP ERROR event %d received for QP=%p, "
 207                         "closing transport\n",
 208                         event->event, event->element.qp);
 209                 set_bit(XPT_CLOSE, &xprt->xpt_flags);
 210                 break;
 211         }
 212 }
 213
 214 /*
 215  * Data Transfer Operation Tasklet
 216  *
 217  * Walks a list of transports with I/O pending, removing entries as
 218  * they are added to the server's I/O pending list. Two bits indicate
 219  * if SQ, RQ, or both have I/O pending. The dto_lock is an irqsave
 220  * spinlock that serializes access to the transport list with the RQ
 221  * and SQ interrupt handlers.
 222  */
 223 static void dto_tasklet_func(unsigned long data)
 224 {
 225         struct svcxprt_rdma *xprt;
 226         unsigned long flags;
 227
 228         spin_lock_irqsave(&dto_lock, flags);
 229         while (!list_empty(&dto_xprt_q)) {
 230                 xprt = list_entry(dto_xprt_q.next,
 231                                   struct svcxprt_rdma, sc_dto_q);
 232                 list_del_init(&xprt->sc_dto_q);
 233                 spin_unlock_irqrestore(&dto_lock, flags);
 234
 235                 rq_cq_reap(xprt);
 236                 sq_cq_reap(xprt);
 237
 238                 svc_xprt_put(&xprt->sc_xprt);
 239                 spin_lock_irqsave(&dto_lock, flags);
 240         }
 241         spin_unlock_irqrestore(&dto_lock, flags);
 242 }
 243
 244 /*
 245  * Receive Queue Completion Handler
 246  *
 247  * Since an RQ completion handler is called on interrupt context, we
 248  * need to defer the handling of the I/O to a tasklet
 249  */
 250 static void rq_comp_handler(struct ib_cq *cq, void *cq_context)
 251 {
 252         struct svcxprt_rdma *xprt = cq_context;
 253         unsigned long flags;
 254
 255         /*
 256          * Set the bit regardless of whether or not it's on the list
 257          * because it may be on the list already due to an SQ
 258          * completion.
 259         */
 260         set_bit(RDMAXPRT_RQ_PENDING, &xprt->sc_flags);
 261
 262         /*
 263          * If this transport is not already on the DTO transport queue,
 264          * add it
 265          */
 266         spin_lock_irqsave(&dto_lock, flags);
 267         if (list_empty(&xprt->sc_dto_q)) {
 268                 svc_xprt_get(&xprt->sc_xprt);
 269                 list_add_tail(&xprt->sc_dto_q, &dto_xprt_q);
 270         }
 271         spin_unlock_irqrestore(&dto_lock, flags);
 272
 273         /* Tasklet does all the work to avoid irqsave locks. */
 274         tasklet_schedule(&dto_tasklet);
 275 }
 276
 277 /*
 278  * rq_cq_reap - Process the RQ CQ.
 279  *
 280  * Take all completing WC off the CQE and enqueue the associated DTO
 281  * context on the dto_q for the transport.
 282  *
 283  * Note that caller must hold a transport reference.
 284  */
 285 static void rq_cq_reap(struct svcxprt_rdma *xprt)
 286 {
 287         int ret;
 288         struct ib_wc wc;
 289         struct svc_rdma_op_ctxt *ctxt = NULL;
 290
 291         if (!test_and_clear_bit(RDMAXPRT_RQ_PENDING, &xprt->sc_flags))
 292                 return;
 293
 294         ib_req_notify_cq(xprt->sc_rq_cq, IB_CQ_NEXT_COMP);
 295         atomic_inc(&rdma_stat_rq_poll);
 296
 297         while ((ret = ib_poll_cq(xprt->sc_rq_cq, 1, &wc)) > 0) {
 298                 ctxt = (struct svc_rdma_op_ctxt *)(unsigned long)wc.wr_id;
 299                 ctxt->wc_status = wc.status;
 300                 ctxt->byte_len = wc.byte_len;
 301                 if (wc.status != IB_WC_SUCCESS) {
 302                         /* Close the transport */
 303                         dprintk("svcrdma: transport closing putting ctxt %p\n", ctxt);
 304                         set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
 305                         svc_rdma_put_context(ctxt, 1);
 306                         svc_xprt_put(&xprt->sc_xprt);
 307                         continue;
 308                 }
 309                 spin_lock_bh(&xprt->sc_rq_dto_lock);
 310                 list_add_tail(&ctxt->dto_q, &xprt->sc_rq_dto_q);
 311                 spin_unlock_bh(&xprt->sc_rq_dto_lock);
 312                 svc_xprt_put(&xprt->sc_xprt);
 313         }
 314
 315         if (ctxt)
 316                 atomic_inc(&rdma_stat_rq_prod);
 317
 318         set_bit(XPT_DATA, &xprt->sc_xprt.xpt_flags);
 319         /*
 320          * If data arrived before established event,
 321          * don't enqueue. This defers RPC I/O until the
 322          * RDMA connection is complete.
 323          */
 324         if (!test_bit(RDMAXPRT_CONN_PENDING, &xprt->sc_flags))
 325                 svc_xprt_enqueue(&xprt->sc_xprt);
 326 }
 327
 328 /*
 329  * Send Queue Completion Handler - potentially called on interrupt context.
 330  *
 331  * Note that caller must hold a transport reference.
 332  */
 333 static void sq_cq_reap(struct svcxprt_rdma *xprt)
 334 {
 335         struct svc_rdma_op_ctxt *ctxt = NULL;
 336         struct ib_wc wc;
 337         struct ib_cq *cq = xprt->sc_sq_cq;
 338         int ret;
 339
 340
 341         if (!test_and_clear_bit(RDMAXPRT_SQ_PENDING, &xprt->sc_flags))
 342                 return;
 343
 344         ib_req_notify_cq(xprt->sc_sq_cq, IB_CQ_NEXT_COMP);
 345         atomic_inc(&rdma_stat_sq_poll);
 346         while ((ret = ib_poll_cq(cq, 1, &wc)) > 0) {
 347                 ctxt = (struct svc_rdma_op_ctxt *)(unsigned long)wc.wr_id;
 348                 xprt = ctxt->xprt;
 349
 350                 if (wc.status != IB_WC_SUCCESS)
 351                         /* Close the transport */
 352                         set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
 353
 354                 /* Decrement used SQ WR count */
 355                 atomic_dec(&xprt->sc_sq_count);
 356                 wake_up(&xprt->sc_send_wait);
 357
 358                 switch (ctxt->wr_op) {
 359                 case IB_WR_SEND:
 360                 case IB_WR_RDMA_WRITE:
 361                         svc_rdma_put_context(ctxt, 1);
 362                         break;
 363
 364                 case IB_WR_RDMA_READ:
 365                         if (test_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags)) {
 366                                 struct svc_rdma_op_ctxt *read_hdr = ctxt->read_hdr;
 367                                 BUG_ON(!read_hdr);
 368                                 set_bit(XPT_DATA, &xprt->sc_xprt.xpt_flags);
 369                                 spin_lock_bh(&xprt->sc_read_complete_lock);
 370                                 list_add_tail(&read_hdr->dto_q,
 371                                               &xprt->sc_read_complete_q);
 372                                 spin_unlock_bh(&xprt->sc_read_complete_lock);
 373                                 svc_xprt_enqueue(&xprt->sc_xprt);
 374                         }
 375                         svc_rdma_put_context(ctxt, 0);
 376                         break;
 377
 378                 default:
 379                         printk(KERN_ERR "svcrdma: unexpected completion type, "
 380                                "opcode=%d, status=%d\n",
 381                                wc.opcode, wc.status);
 382                         break;
 383                 }
 384                 svc_xprt_put(&xprt->sc_xprt);
 385         }
 386
 387         if (ctxt)
 388                 atomic_inc(&rdma_stat_sq_prod);
 389 }
 390
 391 static void sq_comp_handler(struct ib_cq *cq, void *cq_context)
 392 {
 393         struct svcxprt_rdma *xprt = cq_context;
 394         unsigned long flags;
 395
 396         /*
 397          * Set the bit regardless of whether or not it's on the list
 398          * because it may be on the list already due to an RQ
 399          * completion.
 400         */
 401         set_bit(RDMAXPRT_SQ_PENDING, &xprt->sc_flags);
 402
 403         /*
 404          * If this transport is not already on the DTO transport queue,
 405          * add it
 406          */
 407         spin_lock_irqsave(&dto_lock, flags);
 408         if (list_empty(&xprt->sc_dto_q)) {
 409                 svc_xprt_get(&xprt->sc_xprt);
 410                 list_add_tail(&xprt->sc_dto_q, &dto_xprt_q);
 411         }
 412         spin_unlock_irqrestore(&dto_lock, flags);
 413
 414         /* Tasklet does all the work to avoid irqsave locks. */
 415         tasklet_schedule(&dto_tasklet);
 416 }
 417
 418 static void create_context_cache(struct svcxprt_rdma *xprt,
 419                                  int ctxt_count, int ctxt_bump, int ctxt_max)
 420 {
 421         struct svc_rdma_op_ctxt *ctxt;
 422         int i;
 423
 424         xprt->sc_ctxt_max = ctxt_max;
 425         xprt->sc_ctxt_bump = ctxt_bump;
 426         xprt->sc_ctxt_cnt = 0;
 427         atomic_set(&xprt->sc_ctxt_used, 0);
 428
 429         INIT_LIST_HEAD(&xprt->sc_ctxt_free);
 430         for (i = 0; i < ctxt_count; i++) {
 431                 ctxt = kmalloc(sizeof(*ctxt), GFP_KERNEL);
 432                 if (ctxt) {
 433                         INIT_LIST_HEAD(&ctxt->free_list);
 434                         list_add(&ctxt->free_list, &xprt->sc_ctxt_free);
 435                         xprt->sc_ctxt_cnt++;
 436                 }
 437         }
 438 }
 439
 440 static void destroy_context_cache(struct svcxprt_rdma *xprt)
 441 {
 442         while (!list_empty(&xprt->sc_ctxt_free)) {
 443                 struct svc_rdma_op_ctxt *ctxt;
 444                 ctxt = list_entry(xprt->sc_ctxt_free.next,
 445                                   struct svc_rdma_op_ctxt,
 446                                   free_list);
 447                 list_del_init(&ctxt->free_list);
 448                 kfree(ctxt);
 449         }
 450 }
 451
 452 static struct svcxprt_rdma *rdma_create_xprt(struct svc_serv *serv,
 453                                              int listener)
 454 {
 455         struct svcxprt_rdma *cma_xprt = kzalloc(sizeof *cma_xprt, GFP_KERNEL);
 456
 457         if (!cma_xprt)
 458                 return NULL;
 459         svc_xprt_init(&svc_rdma_class, &cma_xprt->sc_xprt, serv);
 460         INIT_LIST_HEAD(&cma_xprt->sc_accept_q);
 461         INIT_LIST_HEAD(&cma_xprt->sc_dto_q);
 462         INIT_LIST_HEAD(&cma_xprt->sc_rq_dto_q);
 463         INIT_LIST_HEAD(&cma_xprt->sc_read_complete_q);
 464         init_waitqueue_head(&cma_xprt->sc_send_wait);
 465
 466         spin_lock_init(&cma_xprt->sc_lock);
 467         spin_lock_init(&cma_xprt->sc_read_complete_lock);
 468         spin_lock_init(&cma_xprt->sc_ctxt_lock);
 469         spin_lock_init(&cma_xprt->sc_rq_dto_lock);
 470
 471         cma_xprt->sc_ord = svcrdma_ord;
 472
 473         cma_xprt->sc_max_req_size = svcrdma_max_req_size;
 474         cma_xprt->sc_max_requests = svcrdma_max_requests;
 475         cma_xprt->sc_sq_depth = svcrdma_max_requests * RPCRDMA_SQ_DEPTH_MULT;
 476         atomic_set(&cma_xprt->sc_sq_count, 0);
 477
 478         if (!listener) {
 479                 int reqs = cma_xprt->sc_max_requests;
 480                 create_context_cache(cma_xprt,
 481                                      reqs << 1, /* starting size */
 482                                      reqs,      /* bump amount */
 483                                      reqs +
 484                                      cma_xprt->sc_sq_depth +
 485                                      RPCRDMA_MAX_THREADS + 1); /* max */
 486                 if (list_empty(&cma_xprt->sc_ctxt_free)) {
 487                         kfree(cma_xprt);
 488                         return NULL;
 489                 }
 490                 clear_bit(XPT_LISTENER, &cma_xprt->sc_xprt.xpt_flags);
 491         } else
 492                 set_bit(XPT_LISTENER, &cma_xprt->sc_xprt.xpt_flags);
 493
 494         return cma_xprt;
 495 }
 496
 497 struct page *svc_rdma_get_page(void)
 498 {
 499         struct page *page;
 500
 501         while ((page = alloc_page(GFP_KERNEL)) == NULL) {
 502                 /* If we can't get memory, wait a bit and try again */
 503                 printk(KERN_INFO "svcrdma: out of memory...retrying in 1000 "
 504                        "jiffies.\n");
 505                 schedule_timeout_uninterruptible(msecs_to_jiffies(1000));
 506         }
 507         return page;
 508 }
 509
 510 int svc_rdma_post_recv(struct svcxprt_rdma *xprt)
 511 {
 512         struct ib_recv_wr recv_wr, *bad_recv_wr;
 513         struct svc_rdma_op_ctxt *ctxt;
 514         struct page *page;
 515         unsigned long pa;
 516         int sge_no;
 517         int buflen;
 518         int ret;
 519
 520         ctxt = svc_rdma_get_context(xprt);
 521         buflen = 0;
 522         ctxt->direction = DMA_FROM_DEVICE;
 523         for (sge_no = 0; buflen < xprt->sc_max_req_size; sge_no++) {
 524                 BUG_ON(sge_no >= xprt->sc_max_sge);
 525                 page = svc_rdma_get_page();
 526                 ctxt->pages[sge_no] = page;
 527                 pa = ib_dma_map_page(xprt->sc_cm_id->device,
 528                                      page, 0, PAGE_SIZE,
 529                                      DMA_FROM_DEVICE);
 530                 ctxt->sge[sge_no].addr = pa;
 531                 ctxt->sge[sge_no].length = PAGE_SIZE;
 532                 ctxt->sge[sge_no].lkey = xprt->sc_phys_mr->lkey;
 533                 buflen += PAGE_SIZE;
 534         }
 535         ctxt->count = sge_no;
 536         recv_wr.next = NULL;
 537         recv_wr.sg_list = &ctxt->sge[0];
 538         recv_wr.num_sge = ctxt->count;
 539         recv_wr.wr_id = (u64)(unsigned long)ctxt;
 540
 541         svc_xprt_get(&xprt->sc_xprt);
 542         ret = ib_post_recv(xprt->sc_qp, &recv_wr, &bad_recv_wr);
 543         if (ret) {
 544                 svc_xprt_put(&xprt->sc_xprt);
 545                 svc_rdma_put_context(ctxt, 1);
 546         }
 547         return ret;
 548 }
 549
 550 /*
 551  * This function handles the CONNECT_REQUEST event on a listening
 552  * endpoint. It is passed the cma_id for the _new_ connection. The context in
 553  * this cma_id is inherited from the listening cma_id and is the svc_xprt
 554  * structure for the listening endpoint.
 555  *
 556  * This function creates a new xprt for the new connection and enqueues it on
 557  * the accept queue for the listent xprt. When the listen thread is kicked, it
 558  * will call the recvfrom method on the listen xprt which will accept the new
 559  * connection.
 560  */
 561 static void handle_connect_req(struct rdma_cm_id *new_cma_id)
 562 {
 563         struct svcxprt_rdma *listen_xprt = new_cma_id->context;
 564         struct svcxprt_rdma *newxprt;
 565
 566         /* Create a new transport */
 567         newxprt = rdma_create_xprt(listen_xprt->sc_xprt.xpt_server, 0);
 568         if (!newxprt) {
 569                 dprintk("svcrdma: failed to create new transport\n");
 570                 return;
 571         }
 572         newxprt->sc_cm_id = new_cma_id;
 573         new_cma_id->context = newxprt;
 574         dprintk("svcrdma: Creating newxprt=%p, cm_id=%p, listenxprt=%p\n",
 575                 newxprt, newxprt->sc_cm_id, listen_xprt);
 576
 577         /*
 578          * Enqueue the new transport on the accept queue of the listening
 579          * transport
 580          */
 581         spin_lock_bh(&listen_xprt->sc_lock);
 582         list_add_tail(&newxprt->sc_accept_q, &listen_xprt->sc_accept_q);
 583         spin_unlock_bh(&listen_xprt->sc_lock);
 584
 585         /*
 586          * Can't use svc_xprt_received here because we are not on a
 587          * rqstp thread
 588         */
 589         set_bit(XPT_CONN, &listen_xprt->sc_xprt.xpt_flags);
 590         svc_xprt_enqueue(&listen_xprt->sc_xprt);
 591 }
 592
 593 /*
 594  * Handles events generated on the listening endpoint. These events will be
 595  * either be incoming connect requests or adapter removal  events.
 596  */
 597 static int rdma_listen_handler(struct rdma_cm_id *cma_id,
 598                                struct rdma_cm_event *event)
 599 {
 600         struct svcxprt_rdma *xprt = cma_id->context;
 601         int ret = 0;
 602
 603         switch (event->event) {
 604         case RDMA_CM_EVENT_CONNECT_REQUEST:
 605                 dprintk("svcrdma: Connect request on cma_id=%p, xprt = %p, "
 606                         "event=%d\n", cma_id, cma_id->context, event->event);
 607                 handle_connect_req(cma_id);
 608                 break;
 609
 610         case RDMA_CM_EVENT_ESTABLISHED:
 611                 /* Accept complete */
 612                 dprintk("svcrdma: Connection completed on LISTEN xprt=%p, "
 613                         "cm_id=%p\n", xprt, cma_id);
 614                 break;
 615
 616         case RDMA_CM_EVENT_DEVICE_REMOVAL:
 617                 dprintk("svcrdma: Device removal xprt=%p, cm_id=%p\n",
 618                         xprt, cma_id);
 619                 if (xprt)
 620                         set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
 621                 break;
 622
 623         default:
 624                 dprintk("svcrdma: Unexpected event on listening endpoint %p, "
 625                         "event=%d\n", cma_id, event->event);
 626                 break;
 627         }
 628
 629         return ret;
 630 }
 631
 632 static int rdma_cma_handler(struct rdma_cm_id *cma_id,
 633                             struct rdma_cm_event *event)
 634 {
 635         struct svc_xprt *xprt = cma_id->context;
 636         struct svcxprt_rdma *rdma =
 637                 container_of(xprt, struct svcxprt_rdma, sc_xprt);
 638         switch (event->event) {
 639         case RDMA_CM_EVENT_ESTABLISHED:
 640                 /* Accept complete */
 641                 svc_xprt_get(xprt);
 642                 dprintk("svcrdma: Connection completed on DTO xprt=%p, "
 643                         "cm_id=%p\n", xprt, cma_id);
 644                 clear_bit(RDMAXPRT_CONN_PENDING, &rdma->sc_flags);
 645                 svc_xprt_enqueue(xprt);
 646                 break;
 647         case RDMA_CM_EVENT_DISCONNECTED:
 648                 dprintk("svcrdma: Disconnect on DTO xprt=%p, cm_id=%p\n",
 649                         xprt, cma_id);
 650                 if (xprt) {
 651                         set_bit(XPT_CLOSE, &xprt->xpt_flags);
 652                         svc_xprt_enqueue(xprt);
 653                         svc_xprt_put(xprt);
 654                 }
 655                 break;
 656         case RDMA_CM_EVENT_DEVICE_REMOVAL:
 657                 dprintk("svcrdma: Device removal cma_id=%p, xprt = %p, "
 658                         "event=%d\n", cma_id, xprt, event->event);
 659                 if (xprt) {
 660                         set_bit(XPT_CLOSE, &xprt->xpt_flags);
 661                         svc_xprt_enqueue(xprt);
 662                 }
 663                 break;
 664         default:
 665                 dprintk("svcrdma: Unexpected event on DTO endpoint %p, "
 666                         "event=%d\n", cma_id, event->event);
 667                 break;
 668         }
 669         return 0;
 670 }
 671
 672 /*
 673  * Create a listening RDMA service endpoint.
 674  */
 675 static struct svc_xprt *svc_rdma_create(struct svc_serv *serv,
 676                                         struct sockaddr *sa, int salen,
 677                                         int flags)
 678 {
 679         struct rdma_cm_id *listen_id;
 680         struct svcxprt_rdma *cma_xprt;
 681         struct svc_xprt *xprt;
 682         int ret;
 683
 684         dprintk("svcrdma: Creating RDMA socket\n");
 685
 686         cma_xprt = rdma_create_xprt(serv, 1);
 687         if (!cma_xprt)
 688                 return ERR_PTR(-ENOMEM);
 689         xprt = &cma_xprt->sc_xprt;
 690
 691         listen_id = rdma_create_id(rdma_listen_handler, cma_xprt, RDMA_PS_TCP);
 692         if (IS_ERR(listen_id)) {
 693                 ret = PTR_ERR(listen_id);
 694                 dprintk("svcrdma: rdma_create_id failed = %d\n", ret);
 695                 goto err0;
 696         }
 697
 698         ret = rdma_bind_addr(listen_id, sa);
 699         if (ret) {
 700                 dprintk("svcrdma: rdma_bind_addr failed = %d\n", ret);
 701                 goto err1;
 702         }
 703         cma_xprt->sc_cm_id = listen_id;
 704
 705         ret = rdma_listen(listen_id, RPCRDMA_LISTEN_BACKLOG);
 706         if (ret) {
 707                 dprintk("svcrdma: rdma_listen failed = %d\n", ret);
 708                 goto err1;
 709         }
 710
 711         /*
 712          * We need to use the address from the cm_id in case the
 713          * caller specified 0 for the port number.
 714          */
 715         sa = (struct sockaddr *)&cma_xprt->sc_cm_id->route.addr.src_addr;
 716         svc_xprt_set_local(&cma_xprt->sc_xprt, sa, salen);
 717
 718         return &cma_xprt->sc_xprt;
 719
 720  err1:
 721         rdma_destroy_id(listen_id);
 722  err0:
 723         kfree(cma_xprt);
 724         return ERR_PTR(ret);
 725 }
 726
 727 /*
 728  * This is the xpo_recvfrom function for listening endpoints. Its
 729  * purpose is to accept incoming connections. The CMA callback handler
 730  * has already created a new transport and attached it to the new CMA
 731  * ID.
 732  *
 733  * There is a queue of pending connections hung on the listening
 734  * transport. This queue contains the new svc_xprt structure. This
 735  * function takes svc_xprt structures off the accept_q and completes
 736  * the connection.
 737  */
 738 static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
 739 {
 740         struct svcxprt_rdma *listen_rdma;
 741         struct svcxprt_rdma *newxprt = NULL;
 742         struct rdma_conn_param conn_param;
 743         struct ib_qp_init_attr qp_attr;
 744         struct ib_device_attr devattr;
 745         struct sockaddr *sa;
 746         int ret;
 747         int i;
 748
 749         listen_rdma = container_of(xprt, struct svcxprt_rdma, sc_xprt);
 750         clear_bit(XPT_CONN, &xprt->xpt_flags);
 751         /* Get the next entry off the accept list */
 752         spin_lock_bh(&listen_rdma->sc_lock);
 753         if (!list_empty(&listen_rdma->sc_accept_q)) {
 754                 newxprt = list_entry(listen_rdma->sc_accept_q.next,
 755                                      struct svcxprt_rdma, sc_accept_q);
 756                 list_del_init(&newxprt->sc_accept_q);
 757         }
 758         if (!list_empty(&listen_rdma->sc_accept_q))
 759                 set_bit(XPT_CONN, &listen_rdma->sc_xprt.xpt_flags);
 760         spin_unlock_bh(&listen_rdma->sc_lock);
 761         if (!newxprt)
 762                 return NULL;
 763
 764         dprintk("svcrdma: newxprt from accept queue = %p, cm_id=%p\n",
 765                 newxprt, newxprt->sc_cm_id);
 766
 767         ret = ib_query_device(newxprt->sc_cm_id->device, &devattr);
 768         if (ret) {
 769                 dprintk("svcrdma: could not query device attributes on "
 770                         "device %p, rc=%d\n", newxprt->sc_cm_id->device, ret);
 771                 goto errout;
 772         }
 773
 774         /* Qualify the transport resource defaults with the
 775          * capabilities of this particular device */
 776         newxprt->sc_max_sge = min((size_t)devattr.max_sge,
 777                                   (size_t)RPCSVC_MAXPAGES);
 778         newxprt->sc_max_requests = min((size_t)devattr.max_qp_wr,
 779                                    (size_t)svcrdma_max_requests);
 780         newxprt->sc_sq_depth = RPCRDMA_SQ_DEPTH_MULT * newxprt->sc_max_requests;
 781
 782         newxprt->sc_ord =  min((size_t)devattr.max_qp_rd_atom,
 783                                (size_t)svcrdma_ord);
 784
 785         newxprt->sc_pd = ib_alloc_pd(newxprt->sc_cm_id->device);
 786         if (IS_ERR(newxprt->sc_pd)) {
 787                 dprintk("svcrdma: error creating PD for connect request\n");
 788                 goto errout;
 789         }
 790         newxprt->sc_sq_cq = ib_create_cq(newxprt->sc_cm_id->device,
 791                                          sq_comp_handler,
 792                                          cq_event_handler,
 793                                          newxprt,
 794                                          newxprt->sc_sq_depth,
 795                                          0);
 796         if (IS_ERR(newxprt->sc_sq_cq)) {
 797                 dprintk("svcrdma: error creating SQ CQ for connect request\n");
 798                 goto errout;
 799         }
 800         newxprt->sc_rq_cq = ib_create_cq(newxprt->sc_cm_id->device,
 801                                          rq_comp_handler,
 802                                          cq_event_handler,
 803                                          newxprt,
 804                                          newxprt->sc_max_requests,
 805                                          0);
 806         if (IS_ERR(newxprt->sc_rq_cq)) {
 807                 dprintk("svcrdma: error creating RQ CQ for connect request\n");
 808                 goto errout;
 809         }
 810
 811         memset(&qp_attr, 0, sizeof qp_attr);
 812         qp_attr.event_handler = qp_event_handler;
 813         qp_attr.qp_context = &newxprt->sc_xprt;
 814         qp_attr.cap.max_send_wr = newxprt->sc_sq_depth;
 815         qp_attr.cap.max_recv_wr = newxprt->sc_max_requests;
 816         qp_attr.cap.max_send_sge = newxprt->sc_max_sge;
 817         qp_attr.cap.max_recv_sge = newxprt->sc_max_sge;
 818         qp_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
 819         qp_attr.qp_type = IB_QPT_RC;
 820         qp_attr.send_cq = newxprt->sc_sq_cq;
 821         qp_attr.recv_cq = newxprt->sc_rq_cq;
 822         dprintk("svcrdma: newxprt->sc_cm_id=%p, newxprt->sc_pd=%p\n"
 823                 "    cm_id->device=%p, sc_pd->device=%p\n"
 824                 "    cap.max_send_wr = %d\n"
 825                 "    cap.max_recv_wr = %d\n"
 826                 "    cap.max_send_sge = %d\n"
 827                 "    cap.max_recv_sge = %d\n",
 828                 newxprt->sc_cm_id, newxprt->sc_pd,
 829                 newxprt->sc_cm_id->device, newxprt->sc_pd->device,
 830                 qp_attr.cap.max_send_wr,
 831                 qp_attr.cap.max_recv_wr,
 832                 qp_attr.cap.max_send_sge,
 833                 qp_attr.cap.max_recv_sge);
 834
 835         ret = rdma_create_qp(newxprt->sc_cm_id, newxprt->sc_pd, &qp_attr);
 836         if (ret) {
 837                 /*
 838                  * XXX: This is a hack. We need a xx_request_qp interface
 839                  * that will adjust the qp_attr's with a best-effort
 840                  * number
 841                  */
 842                 qp_attr.cap.max_send_sge -= 2;
 843                 qp_attr.cap.max_recv_sge -= 2;
 844                 ret = rdma_create_qp(newxprt->sc_cm_id, newxprt->sc_pd,
 845                                      &qp_attr);
 846                 if (ret) {
 847                         dprintk("svcrdma: failed to create QP, ret=%d\n", ret);
 848                         goto errout;
 849                 }
 850                 newxprt->sc_max_sge = qp_attr.cap.max_send_sge;
 851                 newxprt->sc_max_sge = qp_attr.cap.max_recv_sge;
 852                 newxprt->sc_sq_depth = qp_attr.cap.max_send_wr;
 853                 newxprt->sc_max_requests = qp_attr.cap.max_recv_wr;
 854         }
 855         svc_xprt_get(&newxprt->sc_xprt);
 856         newxprt->sc_qp = newxprt->sc_cm_id->qp;
 857
 858         /* Register all of physical memory */
 859         newxprt->sc_phys_mr = ib_get_dma_mr(newxprt->sc_pd,
 860                                             IB_ACCESS_LOCAL_WRITE |
 861                                             IB_ACCESS_REMOTE_WRITE);
 862         if (IS_ERR(newxprt->sc_phys_mr)) {
 863                 dprintk("svcrdma: Failed to create DMA MR ret=%d\n", ret);
 864                 goto errout;
 865         }
 866
 867         /* Post receive buffers */
 868         for (i = 0; i < newxprt->sc_max_requests; i++) {
 869                 ret = svc_rdma_post_recv(newxprt);
 870                 if (ret) {
 871                         dprintk("svcrdma: failure posting receive buffers\n");
 872                         goto errout;
 873                 }
 874         }
 875
 876         /* Swap out the handler */
 877         newxprt->sc_cm_id->event_handler = rdma_cma_handler;
 878
 879         /* Accept Connection */
 880         set_bit(RDMAXPRT_CONN_PENDING, &newxprt->sc_flags);
 881         memset(&conn_param, 0, sizeof conn_param);
 882         conn_param.responder_resources = 0;
 883         conn_param.initiator_depth = newxprt->sc_ord;
 884         ret = rdma_accept(newxprt->sc_cm_id, &conn_param);
 885         if (ret) {
 886                 dprintk("svcrdma: failed to accept new connection, ret=%d\n",
 887                        ret);
 888                 goto errout;
 889         }
 890
 891         dprintk("svcrdma: new connection %p accepted with the following "
 892                 "attributes:\n"
 893                 "    local_ip        : %d.%d.%d.%d\n"
 894                 "    local_port      : %d\n"
 895                 "    remote_ip       : %d.%d.%d.%d\n"
 896                 "    remote_port     : %d\n"
 897                 "    max_sge         : %d\n"
 898                 "    sq_depth        : %d\n"
 899                 "    max_requests    : %d\n"
 900                 "    ord             : %d\n",
 901                 newxprt,
 902                 NIPQUAD(((struct sockaddr_in *)&newxprt->sc_cm_id->
 903                          route.addr.src_addr)->sin_addr.s_addr),
 904                 ntohs(((struct sockaddr_in *)&newxprt->sc_cm_id->
 905                        route.addr.src_addr)->sin_port),
 906                 NIPQUAD(((struct sockaddr_in *)&newxprt->sc_cm_id->
 907                          route.addr.dst_addr)->sin_addr.s_addr),
 908                 ntohs(((struct sockaddr_in *)&newxprt->sc_cm_id->
 909                        route.addr.dst_addr)->sin_port),
 910                 newxprt->sc_max_sge,
 911                 newxprt->sc_sq_depth,
 912                 newxprt->sc_max_requests,
 913                 newxprt->sc_ord);
 914
 915         /* Set the local and remote addresses in the transport */
 916         sa = (struct sockaddr *)&newxprt->sc_cm_id->route.addr.dst_addr;
 917         svc_xprt_set_remote(&newxprt->sc_xprt, sa, svc_addr_len(sa));
 918         sa = (struct sockaddr *)&newxprt->sc_cm_id->route.addr.src_addr;
 919         svc_xprt_set_local(&newxprt->sc_xprt, sa, svc_addr_len(sa));
 920
 921         ib_req_notify_cq(newxprt->sc_sq_cq, IB_CQ_NEXT_COMP);
 922         ib_req_notify_cq(newxprt->sc_rq_cq, IB_CQ_NEXT_COMP);
 923         return &newxprt->sc_xprt;
 924
 925  errout:
 926         dprintk("svcrdma: failure accepting new connection rc=%d.\n", ret);
 927         /* Take a reference in case the DTO handler runs */
 928         svc_xprt_get(&newxprt->sc_xprt);
 929         if (newxprt->sc_qp && !IS_ERR(newxprt->sc_qp)) {
 930                 ib_destroy_qp(newxprt->sc_qp);
 931                 svc_xprt_put(&newxprt->sc_xprt);
 932         }
 933         rdma_destroy_id(newxprt->sc_cm_id);
 934         /* This call to put will destroy the transport */
 935         svc_xprt_put(&newxprt->sc_xprt);
 936         return NULL;
 937 }
 938
 939 static void svc_rdma_release_rqst(struct svc_rqst *rqstp)
 940 {
 941 }
 942
 943 /*
 944  * When connected, an svc_xprt has at least three references:
 945  *
 946  * - A reference held by the QP. We still hold that here because this
 947  *   code deletes the QP and puts the reference.
 948  *
 949  * - A reference held by the cm_id between the ESTABLISHED and
 950  *   DISCONNECTED events. If the remote peer disconnected first, this
 951  *   reference could be gone.
 952  *
 953  * - A reference held by the svc_recv code that called this function
 954  *   as part of close processing.
 955  *
 956  * At a minimum two references should still be held.
 957  */
 958 static void svc_rdma_detach(struct svc_xprt *xprt)
 959 {
 960         struct svcxprt_rdma *rdma =
 961                 container_of(xprt, struct svcxprt_rdma, sc_xprt);
 962         dprintk("svc: svc_rdma_detach(%p)\n", xprt);
 963
 964         /* Disconnect and flush posted WQE */
 965         rdma_disconnect(rdma->sc_cm_id);
 966
 967         /* Destroy the QP if present (not a listener) */
 968         if (rdma->sc_qp && !IS_ERR(rdma->sc_qp)) {
 969                 ib_destroy_qp(rdma->sc_qp);
 970                 svc_xprt_put(xprt);
 971         }
 972
 973         /* Destroy the CM ID */
 974         rdma_destroy_id(rdma->sc_cm_id);
 975 }
 976
 977 static void __svc_rdma_free(struct work_struct *work)
 978 {
 979         struct svcxprt_rdma *rdma =
 980                 container_of(work, struct svcxprt_rdma, sc_work);
 981         dprintk("svcrdma: svc_rdma_free(%p)\n", rdma);
 982
 983         /* We should only be called from kref_put */
 984         BUG_ON(atomic_read(&rdma->sc_xprt.xpt_ref.refcount) != 0);
 985
 986         if (rdma->sc_sq_cq && !IS_ERR(rdma->sc_sq_cq))
 987                 ib_destroy_cq(rdma->sc_sq_cq);
 988
 989         if (rdma->sc_rq_cq && !IS_ERR(rdma->sc_rq_cq))
 990                 ib_destroy_cq(rdma->sc_rq_cq);
 991
 992         if (rdma->sc_phys_mr && !IS_ERR(rdma->sc_phys_mr))
 993                 ib_dereg_mr(rdma->sc_phys_mr);
 994
 995         if (rdma->sc_pd && !IS_ERR(rdma->sc_pd))
 996                 ib_dealloc_pd(rdma->sc_pd);
 997
 998         destroy_context_cache(rdma);
 999         kfree(rdma);
1000 }
1001
1002 static void svc_rdma_free(struct svc_xprt *xprt)
1003 {
1004         struct svcxprt_rdma *rdma =
1005                 container_of(xprt, struct svcxprt_rdma, sc_xprt);
1006         INIT_WORK(&rdma->sc_work, __svc_rdma_free);
1007         schedule_work(&rdma->sc_work);
1008 }
1009
1010 static int svc_rdma_has_wspace(struct svc_xprt *xprt)
1011 {
1012         struct svcxprt_rdma *rdma =
1013                 container_of(xprt, struct svcxprt_rdma, sc_xprt);
1014
1015         /*
1016          * If there are fewer SQ WR available than required to send a
1017          * simple response, return false.
1018          */
1019         if ((rdma->sc_sq_depth - atomic_read(&rdma->sc_sq_count) < 3))
1020                 return 0;
1021
1022         /*
1023          * ...or there are already waiters on the SQ,
1024          * return false.
1025          */
1026         if (waitqueue_active(&rdma->sc_send_wait))
1027                 return 0;
1028
1029         /* Otherwise return true. */
1030         return 1;
1031 }
1032
1033 int svc_rdma_send(struct svcxprt_rdma *xprt, struct ib_send_wr *wr)
1034 {
1035         struct ib_send_wr *bad_wr;
1036         int ret;
1037
1038         if (test_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags))
1039                 return -ENOTCONN;
1040
1041         BUG_ON(wr->send_flags != IB_SEND_SIGNALED);
1042         BUG_ON(((struct svc_rdma_op_ctxt *)(unsigned long)wr->wr_id)->wr_op !=
1043                 wr->opcode);
1044         /* If the SQ is full, wait until an SQ entry is available */
1045         while (1) {
1046                 spin_lock_bh(&xprt->sc_lock);
1047                 if (xprt->sc_sq_depth == atomic_read(&xprt->sc_sq_count)) {
1048                         spin_unlock_bh(&xprt->sc_lock);
1049                         atomic_inc(&rdma_stat_sq_starve);
1050
1051                         /* See if we can opportunistically reap SQ WR to make room */
1052                         sq_cq_reap(xprt);
1053
1054                         /* Wait until SQ WR available if SQ still full */
1055                         wait_event(xprt->sc_send_wait,
1056                                    atomic_read(&xprt->sc_sq_count) <
1057                                    xprt->sc_sq_depth);
1058                         if (test_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags))
1059                                 return 0;
1060                         continue;
1061                 }
1062                 /* Bumped used SQ WR count and post */
1063                 svc_xprt_get(&xprt->sc_xprt);
1064                 ret = ib_post_send(xprt->sc_qp, wr, &bad_wr);
1065                 if (!ret)
1066                         atomic_inc(&xprt->sc_sq_count);
1067                 else {
1068                         svc_xprt_put(&xprt->sc_xprt);
1069                         dprintk("svcrdma: failed to post SQ WR rc=%d, "
1070                                "sc_sq_count=%d, sc_sq_depth=%d\n",
1071                                ret, atomic_read(&xprt->sc_sq_count),
1072                                xprt->sc_sq_depth);
1073                 }
1074                 spin_unlock_bh(&xprt->sc_lock);
1075                 break;
1076         }
1077         return ret;
1078 }
1079
1080 int svc_rdma_send_error(struct svcxprt_rdma *xprt, struct rpcrdma_msg *rmsgp,
1081                         enum rpcrdma_errcode err)
1082 {
1083         struct ib_send_wr err_wr;
1084         struct ib_sge sge;
1085         struct page *p;
1086         struct svc_rdma_op_ctxt *ctxt;
1087         u32 *va;
1088         int length;
1089         int ret;
1090
1091         p = svc_rdma_get_page();
1092         va = page_address(p);
1093
1094         /* XDR encode error */
1095         length = svc_rdma_xdr_encode_error(xprt, rmsgp, err, va);
1096
1097         /* Prepare SGE for local address */
1098         sge.addr = ib_dma_map_page(xprt->sc_cm_id->device,
1099                                    p, 0, PAGE_SIZE, DMA_FROM_DEVICE);
1100         sge.lkey = xprt->sc_phys_mr->lkey;
1101         sge.length = length;
1102
1103         ctxt = svc_rdma_get_context(xprt);
1104         ctxt->count = 1;
1105         ctxt->pages[0] = p;
1106
1107         /* Prepare SEND WR */
1108         memset(&err_wr, 0, sizeof err_wr);
1109         ctxt->wr_op = IB_WR_SEND;
1110         err_wr.wr_id = (unsigned long)ctxt;
1111         err_wr.sg_list = &sge;
1112         err_wr.num_sge = 1;
1113         err_wr.opcode = IB_WR_SEND;
1114         err_wr.send_flags = IB_SEND_SIGNALED;
1115
1116         /* Post It */
1117         ret = svc_rdma_send(xprt, &err_wr);
1118         if (ret) {
1119                 dprintk("svcrdma: Error posting send = %d\n", ret);
1120                 svc_rdma_put_context(ctxt, 1);
1121         }
1122
1123         return ret;
1124 }