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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 static void rq_cq_reap(struct svcxprt_rdma *xprt)
 284 {
 285         int ret;
 286         struct ib_wc wc;
 287         struct svc_rdma_op_ctxt *ctxt = NULL;
 288
 289         if (!test_and_clear_bit(RDMAXPRT_RQ_PENDING, &xprt->sc_flags))
 290                 return;
 291
 292         ib_req_notify_cq(xprt->sc_rq_cq, IB_CQ_NEXT_COMP);
 293         atomic_inc(&rdma_stat_rq_poll);
 294
 295         spin_lock_bh(&xprt->sc_rq_dto_lock);
 296         while ((ret = ib_poll_cq(xprt->sc_rq_cq, 1, &wc)) > 0) {
 297                 ctxt = (struct svc_rdma_op_ctxt *)(unsigned long)wc.wr_id;
 298                 ctxt->wc_status = wc.status;
 299                 ctxt->byte_len = wc.byte_len;
 300                 if (wc.status != IB_WC_SUCCESS) {
 301                         /* Close the transport */
 302                         set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
 303                         svc_rdma_put_context(ctxt, 1);
 304                         continue;
 305                 }
 306                 list_add_tail(&ctxt->dto_q, &xprt->sc_rq_dto_q);
 307         }
 308         spin_unlock_bh(&xprt->sc_rq_dto_lock);
 309
 310         if (ctxt)
 311                 atomic_inc(&rdma_stat_rq_prod);
 312
 313         set_bit(XPT_DATA, &xprt->sc_xprt.xpt_flags);
 314         /*
 315          * If data arrived before established event,
 316          * don't enqueue. This defers RPC I/O until the
 317          * RDMA connection is complete.
 318          */
 319         if (!test_bit(RDMAXPRT_CONN_PENDING, &xprt->sc_flags))
 320                 svc_xprt_enqueue(&xprt->sc_xprt);
 321 }
 322
 323 /*
 324  * Send Queue Completion Handler - potentially called on interrupt context.
 325  */
 326 static void sq_cq_reap(struct svcxprt_rdma *xprt)
 327 {
 328         struct svc_rdma_op_ctxt *ctxt = NULL;
 329         struct ib_wc wc;
 330         struct ib_cq *cq = xprt->sc_sq_cq;
 331         int ret;
 332
 333
 334         if (!test_and_clear_bit(RDMAXPRT_SQ_PENDING, &xprt->sc_flags))
 335                 return;
 336
 337         ib_req_notify_cq(xprt->sc_sq_cq, IB_CQ_NEXT_COMP);
 338         atomic_inc(&rdma_stat_sq_poll);
 339         while ((ret = ib_poll_cq(cq, 1, &wc)) > 0) {
 340                 ctxt = (struct svc_rdma_op_ctxt *)(unsigned long)wc.wr_id;
 341                 xprt = ctxt->xprt;
 342
 343                 if (wc.status != IB_WC_SUCCESS)
 344                         /* Close the transport */
 345                         set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
 346
 347                 /* Decrement used SQ WR count */
 348                 atomic_dec(&xprt->sc_sq_count);
 349                 wake_up(&xprt->sc_send_wait);
 350
 351                 switch (ctxt->wr_op) {
 352                 case IB_WR_SEND:
 353                 case IB_WR_RDMA_WRITE:
 354                         svc_rdma_put_context(ctxt, 1);
 355                         break;
 356
 357                 case IB_WR_RDMA_READ:
 358                         if (test_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags)) {
 359                                 struct svc_rdma_op_ctxt *read_hdr = ctxt->read_hdr;
 360                                 BUG_ON(!read_hdr);
 361                                 set_bit(XPT_DATA, &xprt->sc_xprt.xpt_flags);
 362                                 spin_lock_bh(&xprt->sc_read_complete_lock);
 363                                 list_add_tail(&read_hdr->dto_q,
 364                                               &xprt->sc_read_complete_q);
 365                                 spin_unlock_bh(&xprt->sc_read_complete_lock);
 366                                 svc_xprt_enqueue(&xprt->sc_xprt);
 367                         }
 368                         svc_rdma_put_context(ctxt, 0);
 369                         break;
 370
 371                 default:
 372                         printk(KERN_ERR "svcrdma: unexpected completion type, "
 373                                "opcode=%d, status=%d\n",
 374                                wc.opcode, wc.status);
 375                         break;
 376                 }
 377         }
 378
 379         if (ctxt)
 380                 atomic_inc(&rdma_stat_sq_prod);
 381 }
 382
 383 static void sq_comp_handler(struct ib_cq *cq, void *cq_context)
 384 {
 385         struct svcxprt_rdma *xprt = cq_context;
 386         unsigned long flags;
 387
 388         /*
 389          * Set the bit regardless of whether or not it's on the list
 390          * because it may be on the list already due to an RQ
 391          * completion.
 392         */
 393         set_bit(RDMAXPRT_SQ_PENDING, &xprt->sc_flags);
 394
 395         /*
 396          * If this transport is not already on the DTO transport queue,
 397          * add it
 398          */
 399         spin_lock_irqsave(&dto_lock, flags);
 400         if (list_empty(&xprt->sc_dto_q)) {
 401                 svc_xprt_get(&xprt->sc_xprt);
 402                 list_add_tail(&xprt->sc_dto_q, &dto_xprt_q);
 403         }
 404         spin_unlock_irqrestore(&dto_lock, flags);
 405
 406         /* Tasklet does all the work to avoid irqsave locks. */
 407         tasklet_schedule(&dto_tasklet);
 408 }
 409
 410 static void create_context_cache(struct svcxprt_rdma *xprt,
 411                                  int ctxt_count, int ctxt_bump, int ctxt_max)
 412 {
 413         struct svc_rdma_op_ctxt *ctxt;
 414         int i;
 415
 416         xprt->sc_ctxt_max = ctxt_max;
 417         xprt->sc_ctxt_bump = ctxt_bump;
 418         xprt->sc_ctxt_cnt = 0;
 419         atomic_set(&xprt->sc_ctxt_used, 0);
 420
 421         INIT_LIST_HEAD(&xprt->sc_ctxt_free);
 422         for (i = 0; i < ctxt_count; i++) {
 423                 ctxt = kmalloc(sizeof(*ctxt), GFP_KERNEL);
 424                 if (ctxt) {
 425                         INIT_LIST_HEAD(&ctxt->free_list);
 426                         list_add(&ctxt->free_list, &xprt->sc_ctxt_free);
 427                         xprt->sc_ctxt_cnt++;
 428                 }
 429         }
 430 }
 431
 432 static void destroy_context_cache(struct svcxprt_rdma *xprt)
 433 {
 434         while (!list_empty(&xprt->sc_ctxt_free)) {
 435                 struct svc_rdma_op_ctxt *ctxt;
 436                 ctxt = list_entry(xprt->sc_ctxt_free.next,
 437                                   struct svc_rdma_op_ctxt,
 438                                   free_list);
 439                 list_del_init(&ctxt->free_list);
 440                 kfree(ctxt);
 441         }
 442 }
 443
 444 static struct svcxprt_rdma *rdma_create_xprt(struct svc_serv *serv,
 445                                              int listener)
 446 {
 447         struct svcxprt_rdma *cma_xprt = kzalloc(sizeof *cma_xprt, GFP_KERNEL);
 448
 449         if (!cma_xprt)
 450                 return NULL;
 451         svc_xprt_init(&svc_rdma_class, &cma_xprt->sc_xprt, serv);
 452         INIT_LIST_HEAD(&cma_xprt->sc_accept_q);
 453         INIT_LIST_HEAD(&cma_xprt->sc_dto_q);
 454         INIT_LIST_HEAD(&cma_xprt->sc_rq_dto_q);
 455         INIT_LIST_HEAD(&cma_xprt->sc_read_complete_q);
 456         init_waitqueue_head(&cma_xprt->sc_send_wait);
 457
 458         spin_lock_init(&cma_xprt->sc_lock);
 459         spin_lock_init(&cma_xprt->sc_read_complete_lock);
 460         spin_lock_init(&cma_xprt->sc_ctxt_lock);
 461         spin_lock_init(&cma_xprt->sc_rq_dto_lock);
 462
 463         cma_xprt->sc_ord = svcrdma_ord;
 464
 465         cma_xprt->sc_max_req_size = svcrdma_max_req_size;
 466         cma_xprt->sc_max_requests = svcrdma_max_requests;
 467         cma_xprt->sc_sq_depth = svcrdma_max_requests * RPCRDMA_SQ_DEPTH_MULT;
 468         atomic_set(&cma_xprt->sc_sq_count, 0);
 469
 470         if (!listener) {
 471                 int reqs = cma_xprt->sc_max_requests;
 472                 create_context_cache(cma_xprt,
 473                                      reqs << 1, /* starting size */
 474                                      reqs,      /* bump amount */
 475                                      reqs +
 476                                      cma_xprt->sc_sq_depth +
 477                                      RPCRDMA_MAX_THREADS + 1); /* max */
 478                 if (list_empty(&cma_xprt->sc_ctxt_free)) {
 479                         kfree(cma_xprt);
 480                         return NULL;
 481                 }
 482                 clear_bit(XPT_LISTENER, &cma_xprt->sc_xprt.xpt_flags);
 483         } else
 484                 set_bit(XPT_LISTENER, &cma_xprt->sc_xprt.xpt_flags);
 485
 486         return cma_xprt;
 487 }
 488
 489 struct page *svc_rdma_get_page(void)
 490 {
 491         struct page *page;
 492
 493         while ((page = alloc_page(GFP_KERNEL)) == NULL) {
 494                 /* If we can't get memory, wait a bit and try again */
 495                 printk(KERN_INFO "svcrdma: out of memory...retrying in 1000 "
 496                        "jiffies.\n");
 497                 schedule_timeout_uninterruptible(msecs_to_jiffies(1000));
 498         }
 499         return page;
 500 }
 501
 502 int svc_rdma_post_recv(struct svcxprt_rdma *xprt)
 503 {
 504         struct ib_recv_wr recv_wr, *bad_recv_wr;
 505         struct svc_rdma_op_ctxt *ctxt;
 506         struct page *page;
 507         unsigned long pa;
 508         int sge_no;
 509         int buflen;
 510         int ret;
 511
 512         ctxt = svc_rdma_get_context(xprt);
 513         buflen = 0;
 514         ctxt->direction = DMA_FROM_DEVICE;
 515         for (sge_no = 0; buflen < xprt->sc_max_req_size; sge_no++) {
 516                 BUG_ON(sge_no >= xprt->sc_max_sge);
 517                 page = svc_rdma_get_page();
 518                 ctxt->pages[sge_no] = page;
 519                 pa = ib_dma_map_page(xprt->sc_cm_id->device,
 520                                      page, 0, PAGE_SIZE,
 521                                      DMA_FROM_DEVICE);
 522                 ctxt->sge[sge_no].addr = pa;
 523                 ctxt->sge[sge_no].length = PAGE_SIZE;
 524                 ctxt->sge[sge_no].lkey = xprt->sc_phys_mr->lkey;
 525                 buflen += PAGE_SIZE;
 526         }
 527         ctxt->count = sge_no;
 528         recv_wr.next = NULL;
 529         recv_wr.sg_list = &ctxt->sge[0];
 530         recv_wr.num_sge = ctxt->count;
 531         recv_wr.wr_id = (u64)(unsigned long)ctxt;
 532
 533         ret = ib_post_recv(xprt->sc_qp, &recv_wr, &bad_recv_wr);
 534         if (ret)
 535                 svc_rdma_put_context(ctxt, 1);
 536         return ret;
 537 }
 538
 539 /*
 540  * This function handles the CONNECT_REQUEST event on a listening
 541  * endpoint. It is passed the cma_id for the _new_ connection. The context in
 542  * this cma_id is inherited from the listening cma_id and is the svc_xprt
 543  * structure for the listening endpoint.
 544  *
 545  * This function creates a new xprt for the new connection and enqueues it on
 546  * the accept queue for the listent xprt. When the listen thread is kicked, it
 547  * will call the recvfrom method on the listen xprt which will accept the new
 548  * connection.
 549  */
 550 static void handle_connect_req(struct rdma_cm_id *new_cma_id)
 551 {
 552         struct svcxprt_rdma *listen_xprt = new_cma_id->context;
 553         struct svcxprt_rdma *newxprt;
 554
 555         /* Create a new transport */
 556         newxprt = rdma_create_xprt(listen_xprt->sc_xprt.xpt_server, 0);
 557         if (!newxprt) {
 558                 dprintk("svcrdma: failed to create new transport\n");
 559                 return;
 560         }
 561         newxprt->sc_cm_id = new_cma_id;
 562         new_cma_id->context = newxprt;
 563         dprintk("svcrdma: Creating newxprt=%p, cm_id=%p, listenxprt=%p\n",
 564                 newxprt, newxprt->sc_cm_id, listen_xprt);
 565
 566         /*
 567          * Enqueue the new transport on the accept queue of the listening
 568          * transport
 569          */
 570         spin_lock_bh(&listen_xprt->sc_lock);
 571         list_add_tail(&newxprt->sc_accept_q, &listen_xprt->sc_accept_q);
 572         spin_unlock_bh(&listen_xprt->sc_lock);
 573
 574         /*
 575          * Can't use svc_xprt_received here because we are not on a
 576          * rqstp thread
 577         */
 578         set_bit(XPT_CONN, &listen_xprt->sc_xprt.xpt_flags);
 579         svc_xprt_enqueue(&listen_xprt->sc_xprt);
 580 }
 581
 582 /*
 583  * Handles events generated on the listening endpoint. These events will be
 584  * either be incoming connect requests or adapter removal  events.
 585  */
 586 static int rdma_listen_handler(struct rdma_cm_id *cma_id,
 587                                struct rdma_cm_event *event)
 588 {
 589         struct svcxprt_rdma *xprt = cma_id->context;
 590         int ret = 0;
 591
 592         switch (event->event) {
 593         case RDMA_CM_EVENT_CONNECT_REQUEST:
 594                 dprintk("svcrdma: Connect request on cma_id=%p, xprt = %p, "
 595                         "event=%d\n", cma_id, cma_id->context, event->event);
 596                 handle_connect_req(cma_id);
 597                 break;
 598
 599         case RDMA_CM_EVENT_ESTABLISHED:
 600                 /* Accept complete */
 601                 dprintk("svcrdma: Connection completed on LISTEN xprt=%p, "
 602                         "cm_id=%p\n", xprt, cma_id);
 603                 break;
 604
 605         case RDMA_CM_EVENT_DEVICE_REMOVAL:
 606                 dprintk("svcrdma: Device removal xprt=%p, cm_id=%p\n",
 607                         xprt, cma_id);
 608                 if (xprt)
 609                         set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
 610                 break;
 611
 612         default:
 613                 dprintk("svcrdma: Unexpected event on listening endpoint %p, "
 614                         "event=%d\n", cma_id, event->event);
 615                 break;
 616         }
 617
 618         return ret;
 619 }
 620
 621 static int rdma_cma_handler(struct rdma_cm_id *cma_id,
 622                             struct rdma_cm_event *event)
 623 {
 624         struct svc_xprt *xprt = cma_id->context;
 625         struct svcxprt_rdma *rdma =
 626                 container_of(xprt, struct svcxprt_rdma, sc_xprt);
 627         switch (event->event) {
 628         case RDMA_CM_EVENT_ESTABLISHED:
 629                 /* Accept complete */
 630                 svc_xprt_get(xprt);
 631                 dprintk("svcrdma: Connection completed on DTO xprt=%p, "
 632                         "cm_id=%p\n", xprt, cma_id);
 633                 clear_bit(RDMAXPRT_CONN_PENDING, &rdma->sc_flags);
 634                 svc_xprt_enqueue(xprt);
 635                 break;
 636         case RDMA_CM_EVENT_DISCONNECTED:
 637                 dprintk("svcrdma: Disconnect on DTO xprt=%p, cm_id=%p\n",
 638                         xprt, cma_id);
 639                 if (xprt) {
 640                         set_bit(XPT_CLOSE, &xprt->xpt_flags);
 641                         svc_xprt_enqueue(xprt);
 642                         svc_xprt_put(xprt);
 643                 }
 644                 break;
 645         case RDMA_CM_EVENT_DEVICE_REMOVAL:
 646                 dprintk("svcrdma: Device removal cma_id=%p, xprt = %p, "
 647                         "event=%d\n", cma_id, xprt, event->event);
 648                 if (xprt) {
 649                         set_bit(XPT_CLOSE, &xprt->xpt_flags);
 650                         svc_xprt_enqueue(xprt);
 651                 }
 652                 break;
 653         default:
 654                 dprintk("svcrdma: Unexpected event on DTO endpoint %p, "
 655                         "event=%d\n", cma_id, event->event);
 656                 break;
 657         }
 658         return 0;
 659 }
 660
 661 /*
 662  * Create a listening RDMA service endpoint.
 663  */
 664 static struct svc_xprt *svc_rdma_create(struct svc_serv *serv,
 665                                         struct sockaddr *sa, int salen,
 666                                         int flags)
 667 {
 668         struct rdma_cm_id *listen_id;
 669         struct svcxprt_rdma *cma_xprt;
 670         struct svc_xprt *xprt;
 671         int ret;
 672
 673         dprintk("svcrdma: Creating RDMA socket\n");
 674
 675         cma_xprt = rdma_create_xprt(serv, 1);
 676         if (!cma_xprt)
 677                 return ERR_PTR(-ENOMEM);
 678         xprt = &cma_xprt->sc_xprt;
 679
 680         listen_id = rdma_create_id(rdma_listen_handler, cma_xprt, RDMA_PS_TCP);
 681         if (IS_ERR(listen_id)) {
 682                 ret = PTR_ERR(listen_id);
 683                 dprintk("svcrdma: rdma_create_id failed = %d\n", ret);
 684                 goto err0;
 685         }
 686
 687         ret = rdma_bind_addr(listen_id, sa);
 688         if (ret) {
 689                 dprintk("svcrdma: rdma_bind_addr failed = %d\n", ret);
 690                 goto err1;
 691         }
 692         cma_xprt->sc_cm_id = listen_id;
 693
 694         ret = rdma_listen(listen_id, RPCRDMA_LISTEN_BACKLOG);
 695         if (ret) {
 696                 dprintk("svcrdma: rdma_listen failed = %d\n", ret);
 697                 goto err1;
 698         }
 699
 700         /*
 701          * We need to use the address from the cm_id in case the
 702          * caller specified 0 for the port number.
 703          */
 704         sa = (struct sockaddr *)&cma_xprt->sc_cm_id->route.addr.src_addr;
 705         svc_xprt_set_local(&cma_xprt->sc_xprt, sa, salen);
 706
 707         return &cma_xprt->sc_xprt;
 708
 709  err1:
 710         rdma_destroy_id(listen_id);
 711  err0:
 712         kfree(cma_xprt);
 713         return ERR_PTR(ret);
 714 }
 715
 716 /*
 717  * This is the xpo_recvfrom function for listening endpoints. Its
 718  * purpose is to accept incoming connections. The CMA callback handler
 719  * has already created a new transport and attached it to the new CMA
 720  * ID.
 721  *
 722  * There is a queue of pending connections hung on the listening
 723  * transport. This queue contains the new svc_xprt structure. This
 724  * function takes svc_xprt structures off the accept_q and completes
 725  * the connection.
 726  */
 727 static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
 728 {
 729         struct svcxprt_rdma *listen_rdma;
 730         struct svcxprt_rdma *newxprt = NULL;
 731         struct rdma_conn_param conn_param;
 732         struct ib_qp_init_attr qp_attr;
 733         struct ib_device_attr devattr;
 734         struct sockaddr *sa;
 735         int ret;
 736         int i;
 737
 738         listen_rdma = container_of(xprt, struct svcxprt_rdma, sc_xprt);
 739         clear_bit(XPT_CONN, &xprt->xpt_flags);
 740         /* Get the next entry off the accept list */
 741         spin_lock_bh(&listen_rdma->sc_lock);
 742         if (!list_empty(&listen_rdma->sc_accept_q)) {
 743                 newxprt = list_entry(listen_rdma->sc_accept_q.next,
 744                                      struct svcxprt_rdma, sc_accept_q);
 745                 list_del_init(&newxprt->sc_accept_q);
 746         }
 747         if (!list_empty(&listen_rdma->sc_accept_q))
 748                 set_bit(XPT_CONN, &listen_rdma->sc_xprt.xpt_flags);
 749         spin_unlock_bh(&listen_rdma->sc_lock);
 750         if (!newxprt)
 751                 return NULL;
 752
 753         dprintk("svcrdma: newxprt from accept queue = %p, cm_id=%p\n",
 754                 newxprt, newxprt->sc_cm_id);
 755
 756         ret = ib_query_device(newxprt->sc_cm_id->device, &devattr);
 757         if (ret) {
 758                 dprintk("svcrdma: could not query device attributes on "
 759                         "device %p, rc=%d\n", newxprt->sc_cm_id->device, ret);
 760                 goto errout;
 761         }
 762
 763         /* Qualify the transport resource defaults with the
 764          * capabilities of this particular device */
 765         newxprt->sc_max_sge = min((size_t)devattr.max_sge,
 766                                   (size_t)RPCSVC_MAXPAGES);
 767         newxprt->sc_max_requests = min((size_t)devattr.max_qp_wr,
 768                                    (size_t)svcrdma_max_requests);
 769         newxprt->sc_sq_depth = RPCRDMA_SQ_DEPTH_MULT * newxprt->sc_max_requests;
 770
 771         newxprt->sc_ord =  min((size_t)devattr.max_qp_rd_atom,
 772                                (size_t)svcrdma_ord);
 773
 774         newxprt->sc_pd = ib_alloc_pd(newxprt->sc_cm_id->device);
 775         if (IS_ERR(newxprt->sc_pd)) {
 776                 dprintk("svcrdma: error creating PD for connect request\n");
 777                 goto errout;
 778         }
 779         newxprt->sc_sq_cq = ib_create_cq(newxprt->sc_cm_id->device,
 780                                          sq_comp_handler,
 781                                          cq_event_handler,
 782                                          newxprt,
 783                                          newxprt->sc_sq_depth,
 784                                          0);
 785         if (IS_ERR(newxprt->sc_sq_cq)) {
 786                 dprintk("svcrdma: error creating SQ CQ for connect request\n");
 787                 goto errout;
 788         }
 789         newxprt->sc_rq_cq = ib_create_cq(newxprt->sc_cm_id->device,
 790                                          rq_comp_handler,
 791                                          cq_event_handler,
 792                                          newxprt,
 793                                          newxprt->sc_max_requests,
 794                                          0);
 795         if (IS_ERR(newxprt->sc_rq_cq)) {
 796                 dprintk("svcrdma: error creating RQ CQ for connect request\n");
 797                 goto errout;
 798         }
 799
 800         memset(&qp_attr, 0, sizeof qp_attr);
 801         qp_attr.event_handler = qp_event_handler;
 802         qp_attr.qp_context = &newxprt->sc_xprt;
 803         qp_attr.cap.max_send_wr = newxprt->sc_sq_depth;
 804         qp_attr.cap.max_recv_wr = newxprt->sc_max_requests;
 805         qp_attr.cap.max_send_sge = newxprt->sc_max_sge;
 806         qp_attr.cap.max_recv_sge = newxprt->sc_max_sge;
 807         qp_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
 808         qp_attr.qp_type = IB_QPT_RC;
 809         qp_attr.send_cq = newxprt->sc_sq_cq;
 810         qp_attr.recv_cq = newxprt->sc_rq_cq;
 811         dprintk("svcrdma: newxprt->sc_cm_id=%p, newxprt->sc_pd=%p\n"
 812                 "    cm_id->device=%p, sc_pd->device=%p\n"
 813                 "    cap.max_send_wr = %d\n"
 814                 "    cap.max_recv_wr = %d\n"
 815                 "    cap.max_send_sge = %d\n"
 816                 "    cap.max_recv_sge = %d\n",
 817                 newxprt->sc_cm_id, newxprt->sc_pd,
 818                 newxprt->sc_cm_id->device, newxprt->sc_pd->device,
 819                 qp_attr.cap.max_send_wr,
 820                 qp_attr.cap.max_recv_wr,
 821                 qp_attr.cap.max_send_sge,
 822                 qp_attr.cap.max_recv_sge);
 823
 824         ret = rdma_create_qp(newxprt->sc_cm_id, newxprt->sc_pd, &qp_attr);
 825         if (ret) {
 826                 /*
 827                  * XXX: This is a hack. We need a xx_request_qp interface
 828                  * that will adjust the qp_attr's with a best-effort
 829                  * number
 830                  */
 831                 qp_attr.cap.max_send_sge -= 2;
 832                 qp_attr.cap.max_recv_sge -= 2;
 833                 ret = rdma_create_qp(newxprt->sc_cm_id, newxprt->sc_pd,
 834                                      &qp_attr);
 835                 if (ret) {
 836                         dprintk("svcrdma: failed to create QP, ret=%d\n", ret);
 837                         goto errout;
 838                 }
 839                 newxprt->sc_max_sge = qp_attr.cap.max_send_sge;
 840                 newxprt->sc_max_sge = qp_attr.cap.max_recv_sge;
 841                 newxprt->sc_sq_depth = qp_attr.cap.max_send_wr;
 842                 newxprt->sc_max_requests = qp_attr.cap.max_recv_wr;
 843         }
 844         svc_xprt_get(&newxprt->sc_xprt);
 845         newxprt->sc_qp = newxprt->sc_cm_id->qp;
 846
 847         /* Register all of physical memory */
 848         newxprt->sc_phys_mr = ib_get_dma_mr(newxprt->sc_pd,
 849                                             IB_ACCESS_LOCAL_WRITE |
 850                                             IB_ACCESS_REMOTE_WRITE);
 851         if (IS_ERR(newxprt->sc_phys_mr)) {
 852                 dprintk("svcrdma: Failed to create DMA MR ret=%d\n", ret);
 853                 goto errout;
 854         }
 855
 856         /* Post receive buffers */
 857         for (i = 0; i < newxprt->sc_max_requests; i++) {
 858                 ret = svc_rdma_post_recv(newxprt);
 859                 if (ret) {
 860                         dprintk("svcrdma: failure posting receive buffers\n");
 861                         goto errout;
 862                 }
 863         }
 864
 865         /* Swap out the handler */
 866         newxprt->sc_cm_id->event_handler = rdma_cma_handler;
 867
 868         /* Accept Connection */
 869         set_bit(RDMAXPRT_CONN_PENDING, &newxprt->sc_flags);
 870         memset(&conn_param, 0, sizeof conn_param);
 871         conn_param.responder_resources = 0;
 872         conn_param.initiator_depth = newxprt->sc_ord;
 873         ret = rdma_accept(newxprt->sc_cm_id, &conn_param);
 874         if (ret) {
 875                 dprintk("svcrdma: failed to accept new connection, ret=%d\n",
 876                        ret);
 877                 goto errout;
 878         }
 879
 880         dprintk("svcrdma: new connection %p accepted with the following "
 881                 "attributes:\n"
 882                 "    local_ip        : %d.%d.%d.%d\n"
 883                 "    local_port      : %d\n"
 884                 "    remote_ip       : %d.%d.%d.%d\n"
 885                 "    remote_port     : %d\n"
 886                 "    max_sge         : %d\n"
 887                 "    sq_depth        : %d\n"
 888                 "    max_requests    : %d\n"
 889                 "    ord             : %d\n",
 890                 newxprt,
 891                 NIPQUAD(((struct sockaddr_in *)&newxprt->sc_cm_id->
 892                          route.addr.src_addr)->sin_addr.s_addr),
 893                 ntohs(((struct sockaddr_in *)&newxprt->sc_cm_id->
 894                        route.addr.src_addr)->sin_port),
 895                 NIPQUAD(((struct sockaddr_in *)&newxprt->sc_cm_id->
 896                          route.addr.dst_addr)->sin_addr.s_addr),
 897                 ntohs(((struct sockaddr_in *)&newxprt->sc_cm_id->
 898                        route.addr.dst_addr)->sin_port),
 899                 newxprt->sc_max_sge,
 900                 newxprt->sc_sq_depth,
 901                 newxprt->sc_max_requests,
 902                 newxprt->sc_ord);
 903
 904         /* Set the local and remote addresses in the transport */
 905         sa = (struct sockaddr *)&newxprt->sc_cm_id->route.addr.dst_addr;
 906         svc_xprt_set_remote(&newxprt->sc_xprt, sa, svc_addr_len(sa));
 907         sa = (struct sockaddr *)&newxprt->sc_cm_id->route.addr.src_addr;
 908         svc_xprt_set_local(&newxprt->sc_xprt, sa, svc_addr_len(sa));
 909
 910         ib_req_notify_cq(newxprt->sc_sq_cq, IB_CQ_NEXT_COMP);
 911         ib_req_notify_cq(newxprt->sc_rq_cq, IB_CQ_NEXT_COMP);
 912         return &newxprt->sc_xprt;
 913
 914  errout:
 915         dprintk("svcrdma: failure accepting new connection rc=%d.\n", ret);
 916         /* Take a reference in case the DTO handler runs */
 917         svc_xprt_get(&newxprt->sc_xprt);
 918         if (newxprt->sc_qp && !IS_ERR(newxprt->sc_qp)) {
 919                 ib_destroy_qp(newxprt->sc_qp);
 920                 svc_xprt_put(&newxprt->sc_xprt);
 921         }
 922         rdma_destroy_id(newxprt->sc_cm_id);
 923         /* This call to put will destroy the transport */
 924         svc_xprt_put(&newxprt->sc_xprt);
 925         return NULL;
 926 }
 927
 928 static void svc_rdma_release_rqst(struct svc_rqst *rqstp)
 929 {
 930 }
 931
 932 /*
 933  * When connected, an svc_xprt has at least three references:
 934  *
 935  * - A reference held by the QP. We still hold that here because this
 936  *   code deletes the QP and puts the reference.
 937  *
 938  * - A reference held by the cm_id between the ESTABLISHED and
 939  *   DISCONNECTED events. If the remote peer disconnected first, this
 940  *   reference could be gone.
 941  *
 942  * - A reference held by the svc_recv code that called this function
 943  *   as part of close processing.
 944  *
 945  * At a minimum two references should still be held.
 946  */
 947 static void svc_rdma_detach(struct svc_xprt *xprt)
 948 {
 949         struct svcxprt_rdma *rdma =
 950                 container_of(xprt, struct svcxprt_rdma, sc_xprt);
 951         dprintk("svc: svc_rdma_detach(%p)\n", xprt);
 952
 953         /* Disconnect and flush posted WQE */
 954         rdma_disconnect(rdma->sc_cm_id);
 955
 956         /* Destroy the QP if present (not a listener) */
 957         if (rdma->sc_qp && !IS_ERR(rdma->sc_qp)) {
 958                 ib_destroy_qp(rdma->sc_qp);
 959                 svc_xprt_put(xprt);
 960         }
 961
 962         /* Destroy the CM ID */
 963         rdma_destroy_id(rdma->sc_cm_id);
 964 }
 965
 966 static void svc_rdma_free(struct svc_xprt *xprt)
 967 {
 968         struct svcxprt_rdma *rdma = (struct svcxprt_rdma *)xprt;
 969         dprintk("svcrdma: svc_rdma_free(%p)\n", rdma);
 970         /* We should only be called from kref_put */
 971         BUG_ON(atomic_read(&xprt->xpt_ref.refcount) != 0);
 972         if (rdma->sc_sq_cq && !IS_ERR(rdma->sc_sq_cq))
 973                 ib_destroy_cq(rdma->sc_sq_cq);
 974
 975         if (rdma->sc_rq_cq && !IS_ERR(rdma->sc_rq_cq))
 976                 ib_destroy_cq(rdma->sc_rq_cq);
 977
 978         if (rdma->sc_phys_mr && !IS_ERR(rdma->sc_phys_mr))
 979                 ib_dereg_mr(rdma->sc_phys_mr);
 980
 981         if (rdma->sc_pd && !IS_ERR(rdma->sc_pd))
 982                 ib_dealloc_pd(rdma->sc_pd);
 983
 984         destroy_context_cache(rdma);
 985         kfree(rdma);
 986 }
 987
 988 static int svc_rdma_has_wspace(struct svc_xprt *xprt)
 989 {
 990         struct svcxprt_rdma *rdma =
 991                 container_of(xprt, struct svcxprt_rdma, sc_xprt);
 992
 993         /*
 994          * If there are fewer SQ WR available than required to send a
 995          * simple response, return false.
 996          */
 997         if ((rdma->sc_sq_depth - atomic_read(&rdma->sc_sq_count) < 3))
 998                 return 0;
 999
1000         /*
1001          * ...or there are already waiters on the SQ,
1002          * return false.
1003          */
1004         if (waitqueue_active(&rdma->sc_send_wait))
1005                 return 0;
1006
1007         /* Otherwise return true. */
1008         return 1;
1009 }
1010
1011 int svc_rdma_send(struct svcxprt_rdma *xprt, struct ib_send_wr *wr)
1012 {
1013         struct ib_send_wr *bad_wr;
1014         int ret;
1015
1016         if (test_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags))
1017                 return -ENOTCONN;
1018
1019         BUG_ON(wr->send_flags != IB_SEND_SIGNALED);
1020         BUG_ON(((struct svc_rdma_op_ctxt *)(unsigned long)wr->wr_id)->wr_op !=
1021                 wr->opcode);
1022         /* If the SQ is full, wait until an SQ entry is available */
1023         while (1) {
1024                 spin_lock_bh(&xprt->sc_lock);
1025                 if (xprt->sc_sq_depth == atomic_read(&xprt->sc_sq_count)) {
1026                         spin_unlock_bh(&xprt->sc_lock);
1027                         atomic_inc(&rdma_stat_sq_starve);
1028
1029                         /* See if we can opportunistically reap SQ WR to make room */
1030                         sq_cq_reap(xprt);
1031
1032                         /* Wait until SQ WR available if SQ still full */
1033                         wait_event(xprt->sc_send_wait,
1034                                    atomic_read(&xprt->sc_sq_count) <
1035                                    xprt->sc_sq_depth);
1036                         if (test_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags))
1037                                 return 0;
1038                         continue;
1039                 }
1040                 /* Bumped used SQ WR count and post */
1041                 ret = ib_post_send(xprt->sc_qp, wr, &bad_wr);
1042                 if (!ret)
1043                         atomic_inc(&xprt->sc_sq_count);
1044                 else
1045                         dprintk("svcrdma: failed to post SQ WR rc=%d, "
1046                                "sc_sq_count=%d, sc_sq_depth=%d\n",
1047                                ret, atomic_read(&xprt->sc_sq_count),
1048                                xprt->sc_sq_depth);
1049                 spin_unlock_bh(&xprt->sc_lock);
1050                 break;
1051         }
1052         return ret;
1053 }
1054
1055 int svc_rdma_send_error(struct svcxprt_rdma *xprt, struct rpcrdma_msg *rmsgp,
1056                         enum rpcrdma_errcode err)
1057 {
1058         struct ib_send_wr err_wr;
1059         struct ib_sge sge;
1060         struct page *p;
1061         struct svc_rdma_op_ctxt *ctxt;
1062         u32 *va;
1063         int length;
1064         int ret;
1065
1066         p = svc_rdma_get_page();
1067         va = page_address(p);
1068
1069         /* XDR encode error */
1070         length = svc_rdma_xdr_encode_error(xprt, rmsgp, err, va);
1071
1072         /* Prepare SGE for local address */
1073         sge.addr = ib_dma_map_page(xprt->sc_cm_id->device,
1074                                    p, 0, PAGE_SIZE, DMA_FROM_DEVICE);
1075         sge.lkey = xprt->sc_phys_mr->lkey;
1076         sge.length = length;
1077
1078         ctxt = svc_rdma_get_context(xprt);
1079         ctxt->count = 1;
1080         ctxt->pages[0] = p;
1081
1082         /* Prepare SEND WR */
1083         memset(&err_wr, 0, sizeof err_wr);
1084         ctxt->wr_op = IB_WR_SEND;
1085         err_wr.wr_id = (unsigned long)ctxt;
1086         err_wr.sg_list = &sge;
1087         err_wr.num_sge = 1;
1088         err_wr.opcode = IB_WR_SEND;
1089         err_wr.send_flags = IB_SEND_SIGNALED;
1090
1091         /* Post It */
1092         ret = svc_rdma_send(xprt, &err_wr);
1093         if (ret) {
1094                 dprintk("svcrdma: Error posting send = %d\n", ret);
1095                 svc_rdma_put_context(ctxt, 1);
1096         }
1097
1098         return ret;
1099 }