drivers/infiniband/hw/ipath/ipath_ud.c

   1 /*
   2  * Copyright (c) 2005, 2006 PathScale, 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
   8  * OpenIB.org BSD license below:
   9  *
  10  *     Redistribution and use in source and binary forms, with or
  11  *     without modification, are permitted provided that the following
  12  *     conditions are met:
  13  *
  14  *      - Redistributions of source code must retain the above
  15  *        copyright notice, this list of conditions and the following
  16  *        disclaimer.
  17  *
  18  *      - Redistributions in binary form must reproduce the above
  19  *        copyright notice, this list of conditions and the following
  20  *        disclaimer in the documentation and/or other materials
  21  *        provided with the distribution.
  22  *
  23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  30  * SOFTWARE.
  31  */
  32
  33 #include <rdma/ib_smi.h>
  34
  35 #include "ipath_verbs.h"
  36 #include "ips_common.h"
  37
  38 /**
  39  * ipath_ud_loopback - handle send on loopback QPs
  40  * @sqp: the QP
  41  * @ss: the SGE state
  42  * @length: the length of the data to send
  43  * @wr: the work request
  44  * @wc: the work completion entry
  45  *
  46  * This is called from ipath_post_ud_send() to forward a WQE addressed
  47  * to the same HCA.
  48  */
  49 static void ipath_ud_loopback(struct ipath_qp *sqp,
  50                               struct ipath_sge_state *ss,
  51                               u32 length, struct ib_send_wr *wr,
  52                               struct ib_wc *wc)
  53 {
  54         struct ipath_ibdev *dev = to_idev(sqp->ibqp.device);
  55         struct ipath_qp *qp;
  56         struct ib_ah_attr *ah_attr;
  57         unsigned long flags;
  58         struct ipath_rq *rq;
  59         struct ipath_srq *srq;
  60         struct ipath_sge_state rsge;
  61         struct ipath_sge *sge;
  62         struct ipath_rwqe *wqe;
  63
  64         qp = ipath_lookup_qpn(&dev->qp_table, wr->wr.ud.remote_qpn);
  65         if (!qp)
  66                 return;
  67
  68         /*
  69          * Check that the qkey matches (except for QP0, see 9.6.1.4.1).
  70          * Qkeys with the high order bit set mean use the
  71          * qkey from the QP context instead of the WR (see 10.2.5).
  72          */
  73         if (unlikely(qp->ibqp.qp_num &&
  74                      ((int) wr->wr.ud.remote_qkey < 0
  75                       ? qp->qkey : wr->wr.ud.remote_qkey) != qp->qkey)) {
  76                 /* XXX OK to lose a count once in a while. */
  77                 dev->qkey_violations++;
  78                 dev->n_pkt_drops++;
  79                 goto done;
  80         }
  81
  82         /*
  83          * A GRH is expected to preceed the data even if not
  84          * present on the wire.
  85          */
  86         wc->byte_len = length + sizeof(struct ib_grh);
  87
  88         if (wr->opcode == IB_WR_SEND_WITH_IMM) {
  89                 wc->wc_flags = IB_WC_WITH_IMM;
  90                 wc->imm_data = wr->imm_data;
  91         } else {
  92                 wc->wc_flags = 0;
  93                 wc->imm_data = 0;
  94         }
  95
  96         /*
  97          * Get the next work request entry to find where to put the data.
  98          * Note that it is safe to drop the lock after changing rq->tail
  99          * since ipath_post_receive() won't fill the empty slot.
 100          */
 101         if (qp->ibqp.srq) {
 102                 srq = to_isrq(qp->ibqp.srq);
 103                 rq = &srq->rq;
 104         } else {
 105                 srq = NULL;
 106                 rq = &qp->r_rq;
 107         }
 108         spin_lock_irqsave(&rq->lock, flags);
 109         if (rq->tail == rq->head) {
 110                 spin_unlock_irqrestore(&rq->lock, flags);
 111                 dev->n_pkt_drops++;
 112                 goto done;
 113         }
 114         /* Silently drop packets which are too big. */
 115         wqe = get_rwqe_ptr(rq, rq->tail);
 116         if (wc->byte_len > wqe->length) {
 117                 spin_unlock_irqrestore(&rq->lock, flags);
 118                 dev->n_pkt_drops++;
 119                 goto done;
 120         }
 121         wc->wr_id = wqe->wr_id;
 122         rsge.sge = wqe->sg_list[0];
 123         rsge.sg_list = wqe->sg_list + 1;
 124         rsge.num_sge = wqe->num_sge;
 125         if (++rq->tail >= rq->size)
 126                 rq->tail = 0;
 127         if (srq && srq->ibsrq.event_handler) {
 128                 u32 n;
 129
 130                 if (rq->head < rq->tail)
 131                         n = rq->size + rq->head - rq->tail;
 132                 else
 133                         n = rq->head - rq->tail;
 134                 if (n < srq->limit) {
 135                         struct ib_event ev;
 136
 137                         srq->limit = 0;
 138                         spin_unlock_irqrestore(&rq->lock, flags);
 139                         ev.device = qp->ibqp.device;
 140                         ev.element.srq = qp->ibqp.srq;
 141                         ev.event = IB_EVENT_SRQ_LIMIT_REACHED;
 142                         srq->ibsrq.event_handler(&ev,
 143                                                  srq->ibsrq.srq_context);
 144                 } else
 145                         spin_unlock_irqrestore(&rq->lock, flags);
 146         } else
 147                 spin_unlock_irqrestore(&rq->lock, flags);
 148         ah_attr = &to_iah(wr->wr.ud.ah)->attr;
 149         if (ah_attr->ah_flags & IB_AH_GRH) {
 150                 ipath_copy_sge(&rsge, &ah_attr->grh, sizeof(struct ib_grh));
 151                 wc->wc_flags |= IB_WC_GRH;
 152         } else
 153                 ipath_skip_sge(&rsge, sizeof(struct ib_grh));
 154         sge = &ss->sge;
 155         while (length) {
 156                 u32 len = sge->length;
 157
 158                 if (len > length)
 159                         len = length;
 160                 BUG_ON(len == 0);
 161                 ipath_copy_sge(&rsge, sge->vaddr, len);
 162                 sge->vaddr += len;
 163                 sge->length -= len;
 164                 sge->sge_length -= len;
 165                 if (sge->sge_length == 0) {
 166                         if (--ss->num_sge)
 167                                 *sge = *ss->sg_list++;
 168                 } else if (sge->length == 0 && sge->mr != NULL) {
 169                         if (++sge->n >= IPATH_SEGSZ) {
 170                                 if (++sge->m >= sge->mr->mapsz)
 171                                         break;
 172                                 sge->n = 0;
 173                         }
 174                         sge->vaddr =
 175                                 sge->mr->map[sge->m]->segs[sge->n].vaddr;
 176                         sge->length =
 177                                 sge->mr->map[sge->m]->segs[sge->n].length;
 178                 }
 179                 length -= len;
 180         }
 181         wc->status = IB_WC_SUCCESS;
 182         wc->opcode = IB_WC_RECV;
 183         wc->vendor_err = 0;
 184         wc->qp_num = qp->ibqp.qp_num;
 185         wc->src_qp = sqp->ibqp.qp_num;
 186         /* XXX do we know which pkey matched? Only needed for GSI. */
 187         wc->pkey_index = 0;
 188         wc->slid = ipath_layer_get_lid(dev->dd) |
 189                 (ah_attr->src_path_bits &
 190                  ((1 << (dev->mkeyprot_resv_lmc & 7)) - 1));
 191         wc->sl = ah_attr->sl;
 192         wc->dlid_path_bits =
 193                 ah_attr->dlid & ((1 << (dev->mkeyprot_resv_lmc & 7)) - 1);
 194         /* Signal completion event if the solicited bit is set. */
 195         ipath_cq_enter(to_icq(qp->ibqp.recv_cq), wc,
 196                        wr->send_flags & IB_SEND_SOLICITED);
 197
 198 done:
 199         if (atomic_dec_and_test(&qp->refcount))
 200                 wake_up(&qp->wait);
 201 }
 202
 203 /**
 204  * ipath_post_ud_send - post a UD send on QP
 205  * @qp: the QP
 206  * @wr: the work request
 207  *
 208  * Note that we actually send the data as it is posted instead of putting
 209  * the request into a ring buffer.  If we wanted to use a ring buffer,
 210  * we would need to save a reference to the destination address in the SWQE.
 211  */
 212 int ipath_post_ud_send(struct ipath_qp *qp, struct ib_send_wr *wr)
 213 {
 214         struct ipath_ibdev *dev = to_idev(qp->ibqp.device);
 215         struct ipath_other_headers *ohdr;
 216         struct ib_ah_attr *ah_attr;
 217         struct ipath_sge_state ss;
 218         struct ipath_sge *sg_list;
 219         struct ib_wc wc;
 220         u32 hwords;
 221         u32 nwords;
 222         u32 len;
 223         u32 extra_bytes;
 224         u32 bth0;
 225         u16 lrh0;
 226         u16 lid;
 227         int i;
 228         int ret;
 229
 230         if (!(ib_ipath_state_ops[qp->state] & IPATH_PROCESS_SEND_OK)) {
 231                 ret = 0;
 232                 goto bail;
 233         }
 234
 235         /* IB spec says that num_sge == 0 is OK. */
 236         if (wr->num_sge > qp->s_max_sge) {
 237                 ret = -EINVAL;
 238                 goto bail;
 239         }
 240
 241         if (wr->num_sge > 1) {
 242                 sg_list = kmalloc((qp->s_max_sge - 1) * sizeof(*sg_list),
 243                                   GFP_ATOMIC);
 244                 if (!sg_list) {
 245                         ret = -ENOMEM;
 246                         goto bail;
 247                 }
 248         } else
 249                 sg_list = NULL;
 250
 251         /* Check the buffer to send. */
 252         ss.sg_list = sg_list;
 253         ss.sge.mr = NULL;
 254         ss.sge.vaddr = NULL;
 255         ss.sge.length = 0;
 256         ss.sge.sge_length = 0;
 257         ss.num_sge = 0;
 258         len = 0;
 259         for (i = 0; i < wr->num_sge; i++) {
 260                 /* Check LKEY */
 261                 if (to_ipd(qp->ibqp.pd)->user && wr->sg_list[i].lkey == 0) {
 262                         ret = -EINVAL;
 263                         goto bail;
 264                 }
 265
 266                 if (wr->sg_list[i].length == 0)
 267                         continue;
 268                 if (!ipath_lkey_ok(&dev->lk_table, ss.num_sge ?
 269                                    sg_list + ss.num_sge - 1 : &ss.sge,
 270                                    &wr->sg_list[i], 0)) {
 271                         ret = -EINVAL;
 272                         goto bail;
 273                 }
 274                 len += wr->sg_list[i].length;
 275                 ss.num_sge++;
 276         }
 277         extra_bytes = (4 - len) & 3;
 278         nwords = (len + extra_bytes) >> 2;
 279
 280         /* Construct the header. */
 281         ah_attr = &to_iah(wr->wr.ud.ah)->attr;
 282         if (ah_attr->dlid == 0) {
 283                 ret = -EINVAL;
 284                 goto bail;
 285         }
 286         if (ah_attr->dlid >= IPS_MULTICAST_LID_BASE) {
 287                 if (ah_attr->dlid != IPS_PERMISSIVE_LID)
 288                         dev->n_multicast_xmit++;
 289                 else
 290                         dev->n_unicast_xmit++;
 291         } else {
 292                 dev->n_unicast_xmit++;
 293                 lid = ah_attr->dlid &
 294                         ~((1 << (dev->mkeyprot_resv_lmc & 7)) - 1);
 295                 if (unlikely(lid == ipath_layer_get_lid(dev->dd))) {
 296                         /*
 297                          * Pass in an uninitialized ib_wc to save stack
 298                          * space.
 299                          */
 300                         ipath_ud_loopback(qp, &ss, len, wr, &wc);
 301                         goto done;
 302                 }
 303         }
 304         if (ah_attr->ah_flags & IB_AH_GRH) {
 305                 /* Header size in 32-bit words. */
 306                 hwords = 17;
 307                 lrh0 = IPS_LRH_GRH;
 308                 ohdr = &qp->s_hdr.u.l.oth;
 309                 qp->s_hdr.u.l.grh.version_tclass_flow =
 310                         cpu_to_be32((6 << 28) |
 311                                     (ah_attr->grh.traffic_class << 20) |
 312                                     ah_attr->grh.flow_label);
 313                 qp->s_hdr.u.l.grh.paylen =
 314                         cpu_to_be16(((wr->opcode ==
 315                                       IB_WR_SEND_WITH_IMM ? 6 : 5) +
 316                                      nwords + SIZE_OF_CRC) << 2);
 317                 /* next_hdr is defined by C8-7 in ch. 8.4.1 */
 318                 qp->s_hdr.u.l.grh.next_hdr = 0x1B;
 319                 qp->s_hdr.u.l.grh.hop_limit = ah_attr->grh.hop_limit;
 320                 /* The SGID is 32-bit aligned. */
 321                 qp->s_hdr.u.l.grh.sgid.global.subnet_prefix =
 322                         dev->gid_prefix;
 323                 qp->s_hdr.u.l.grh.sgid.global.interface_id =
 324                         ipath_layer_get_guid(dev->dd);
 325                 qp->s_hdr.u.l.grh.dgid = ah_attr->grh.dgid;
 326                 /*
 327                  * Don't worry about sending to locally attached multicast
 328                  * QPs.  It is unspecified by the spec. what happens.
 329                  */
 330         } else {
 331                 /* Header size in 32-bit words. */
 332                 hwords = 7;
 333                 lrh0 = IPS_LRH_BTH;
 334                 ohdr = &qp->s_hdr.u.oth;
 335         }
 336         if (wr->opcode == IB_WR_SEND_WITH_IMM) {
 337                 ohdr->u.ud.imm_data = wr->imm_data;
 338                 wc.imm_data = wr->imm_data;
 339                 hwords += 1;
 340                 bth0 = IB_OPCODE_UD_SEND_ONLY_WITH_IMMEDIATE << 24;
 341         } else if (wr->opcode == IB_WR_SEND) {
 342                 wc.imm_data = 0;
 343                 bth0 = IB_OPCODE_UD_SEND_ONLY << 24;
 344         } else {
 345                 ret = -EINVAL;
 346                 goto bail;
 347         }
 348         lrh0 |= ah_attr->sl << 4;
 349         if (qp->ibqp.qp_type == IB_QPT_SMI)
 350                 lrh0 |= 0xF000; /* Set VL (see ch. 13.5.3.1) */
 351         qp->s_hdr.lrh[0] = cpu_to_be16(lrh0);
 352         qp->s_hdr.lrh[1] = cpu_to_be16(ah_attr->dlid);  /* DEST LID */
 353         qp->s_hdr.lrh[2] = cpu_to_be16(hwords + nwords + SIZE_OF_CRC);
 354         lid = ipath_layer_get_lid(dev->dd);
 355         if (lid) {
 356                 lid |= ah_attr->src_path_bits &
 357                         ((1 << (dev->mkeyprot_resv_lmc & 7)) - 1);
 358                 qp->s_hdr.lrh[3] = cpu_to_be16(lid);
 359         } else
 360                 qp->s_hdr.lrh[3] = IB_LID_PERMISSIVE;
 361         if (wr->send_flags & IB_SEND_SOLICITED)
 362                 bth0 |= 1 << 23;
 363         bth0 |= extra_bytes << 20;
 364         bth0 |= qp->ibqp.qp_type == IB_QPT_SMI ? IPS_DEFAULT_P_KEY :
 365                 ipath_layer_get_pkey(dev->dd, qp->s_pkey_index);
 366         ohdr->bth[0] = cpu_to_be32(bth0);
 367         /*
 368          * Use the multicast QP if the destination LID is a multicast LID.
 369          */
 370         ohdr->bth[1] = ah_attr->dlid >= IPS_MULTICAST_LID_BASE &&
 371                 ah_attr->dlid != IPS_PERMISSIVE_LID ?
 372                 __constant_cpu_to_be32(IPS_MULTICAST_QPN) :
 373                 cpu_to_be32(wr->wr.ud.remote_qpn);
 374         /* XXX Could lose a PSN count but not worth locking */
 375         ohdr->bth[2] = cpu_to_be32(qp->s_next_psn++ & IPS_PSN_MASK);
 376         /*
 377          * Qkeys with the high order bit set mean use the
 378          * qkey from the QP context instead of the WR (see 10.2.5).
 379          */
 380         ohdr->u.ud.deth[0] = cpu_to_be32((int)wr->wr.ud.remote_qkey < 0 ?
 381                                          qp->qkey : wr->wr.ud.remote_qkey);
 382         ohdr->u.ud.deth[1] = cpu_to_be32(qp->ibqp.qp_num);
 383         if (ipath_verbs_send(dev->dd, hwords, (u32 *) &qp->s_hdr,
 384                              len, &ss))
 385                 dev->n_no_piobuf++;
 386
 387 done:
 388         /* Queue the completion status entry. */
 389         if (!test_bit(IPATH_S_SIGNAL_REQ_WR, &qp->s_flags) ||
 390             (wr->send_flags & IB_SEND_SIGNALED)) {
 391                 wc.wr_id = wr->wr_id;
 392                 wc.status = IB_WC_SUCCESS;
 393                 wc.vendor_err = 0;
 394                 wc.opcode = IB_WC_SEND;
 395                 wc.byte_len = len;
 396                 wc.qp_num = qp->ibqp.qp_num;
 397                 wc.src_qp = 0;
 398                 wc.wc_flags = 0;
 399                 /* XXX initialize other fields? */
 400                 ipath_cq_enter(to_icq(qp->ibqp.send_cq), &wc, 0);
 401         }
 402         kfree(sg_list);
 403
 404         ret = 0;
 405
 406 bail:
 407         return ret;
 408 }
 409
 410 /**
 411  * ipath_ud_rcv - receive an incoming UD packet
 412  * @dev: the device the packet came in on
 413  * @hdr: the packet header
 414  * @has_grh: true if the packet has a GRH
 415  * @data: the packet data
 416  * @tlen: the packet length
 417  * @qp: the QP the packet came on
 418  *
 419  * This is called from ipath_qp_rcv() to process an incoming UD packet
 420  * for the given QP.
 421  * Called at interrupt level.
 422  */
 423 void ipath_ud_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
 424                   int has_grh, void *data, u32 tlen, struct ipath_qp *qp)
 425 {
 426         struct ipath_other_headers *ohdr;
 427         int opcode;
 428         u32 hdrsize;
 429         u32 pad;
 430         unsigned long flags;
 431         struct ib_wc wc;
 432         u32 qkey;
 433         u32 src_qp;
 434         struct ipath_rq *rq;
 435         struct ipath_srq *srq;
 436         struct ipath_rwqe *wqe;
 437         u16 dlid;
 438         int header_in_data;
 439
 440         /* Check for GRH */
 441         if (!has_grh) {
 442                 ohdr = &hdr->u.oth;
 443                 hdrsize = 8 + 12 + 8;   /* LRH + BTH + DETH */
 444                 qkey = be32_to_cpu(ohdr->u.ud.deth[0]);
 445                 src_qp = be32_to_cpu(ohdr->u.ud.deth[1]);
 446                 header_in_data = 0;
 447         } else {
 448                 ohdr = &hdr->u.l.oth;
 449                 hdrsize = 8 + 40 + 12 + 8; /* LRH + GRH + BTH + DETH */
 450                 /*
 451                  * The header with GRH is 68 bytes and the core driver sets
 452                  * the eager header buffer size to 56 bytes so the last 12
 453                  * bytes of the IB header is in the data buffer.
 454                  */
 455                 header_in_data =
 456                         ipath_layer_get_rcvhdrentsize(dev->dd) == 16;
 457                 if (header_in_data) {
 458                         qkey = be32_to_cpu(((__be32 *) data)[1]);
 459                         src_qp = be32_to_cpu(((__be32 *) data)[2]);
 460                         data += 12;
 461                 } else {
 462                         qkey = be32_to_cpu(ohdr->u.ud.deth[0]);
 463                         src_qp = be32_to_cpu(ohdr->u.ud.deth[1]);
 464                 }
 465         }
 466         src_qp &= IPS_QPN_MASK;
 467
 468         /*
 469          * Check that the permissive LID is only used on QP0
 470          * and the QKEY matches (see 9.6.1.4.1 and 9.6.1.5.1).
 471          */
 472         if (qp->ibqp.qp_num) {
 473                 if (unlikely(hdr->lrh[1] == IB_LID_PERMISSIVE ||
 474                              hdr->lrh[3] == IB_LID_PERMISSIVE)) {
 475                         dev->n_pkt_drops++;
 476                         goto bail;
 477                 }
 478                 if (unlikely(qkey != qp->qkey)) {
 479                         /* XXX OK to lose a count once in a while. */
 480                         dev->qkey_violations++;
 481                         dev->n_pkt_drops++;
 482                         goto bail;
 483                 }
 484         } else if (hdr->lrh[1] == IB_LID_PERMISSIVE ||
 485                    hdr->lrh[3] == IB_LID_PERMISSIVE) {
 486                 struct ib_smp *smp = (struct ib_smp *) data;
 487
 488                 if (smp->mgmt_class != IB_MGMT_CLASS_SUBN_DIRECTED_ROUTE) {
 489                         dev->n_pkt_drops++;
 490                         goto bail;
 491                 }
 492         }
 493
 494         /* Get the number of bytes the message was padded by. */
 495         pad = (be32_to_cpu(ohdr->bth[0]) >> 20) & 3;
 496         if (unlikely(tlen < (hdrsize + pad + 4))) {
 497                 /* Drop incomplete packets. */
 498                 dev->n_pkt_drops++;
 499                 goto bail;
 500         }
 501         tlen -= hdrsize + pad + 4;
 502
 503         /* Drop invalid MAD packets (see 13.5.3.1). */
 504         if (unlikely((qp->ibqp.qp_num == 0 &&
 505                       (tlen != 256 ||
 506                        (be16_to_cpu(hdr->lrh[0]) >> 12) != 15)) ||
 507                      (qp->ibqp.qp_num == 1 &&
 508                       (tlen != 256 ||
 509                        (be16_to_cpu(hdr->lrh[0]) >> 12) == 15)))) {
 510                 dev->n_pkt_drops++;
 511                 goto bail;
 512         }
 513
 514         /*
 515          * A GRH is expected to preceed the data even if not
 516          * present on the wire.
 517          */
 518         wc.byte_len = tlen + sizeof(struct ib_grh);
 519
 520         /*
 521          * The opcode is in the low byte when its in network order
 522          * (top byte when in host order).
 523          */
 524         opcode = be32_to_cpu(ohdr->bth[0]) >> 24;
 525         if (qp->ibqp.qp_num > 1 &&
 526             opcode == IB_OPCODE_UD_SEND_ONLY_WITH_IMMEDIATE) {
 527                 if (header_in_data) {
 528                         wc.imm_data = *(__be32 *) data;
 529                         data += sizeof(__be32);
 530                 } else
 531                         wc.imm_data = ohdr->u.ud.imm_data;
 532                 wc.wc_flags = IB_WC_WITH_IMM;
 533                 hdrsize += sizeof(u32);
 534         } else if (opcode == IB_OPCODE_UD_SEND_ONLY) {
 535                 wc.imm_data = 0;
 536                 wc.wc_flags = 0;
 537         } else {
 538                 dev->n_pkt_drops++;
 539                 goto bail;
 540         }
 541
 542         /*
 543          * Get the next work request entry to find where to put the data.
 544          * Note that it is safe to drop the lock after changing rq->tail
 545          * since ipath_post_receive() won't fill the empty slot.
 546          */
 547         if (qp->ibqp.srq) {
 548                 srq = to_isrq(qp->ibqp.srq);
 549                 rq = &srq->rq;
 550         } else {
 551                 srq = NULL;
 552                 rq = &qp->r_rq;
 553         }
 554         spin_lock_irqsave(&rq->lock, flags);
 555         if (rq->tail == rq->head) {
 556                 spin_unlock_irqrestore(&rq->lock, flags);
 557                 dev->n_pkt_drops++;
 558                 goto bail;
 559         }
 560         /* Silently drop packets which are too big. */
 561         wqe = get_rwqe_ptr(rq, rq->tail);
 562         if (wc.byte_len > wqe->length) {
 563                 spin_unlock_irqrestore(&rq->lock, flags);
 564                 dev->n_pkt_drops++;
 565                 goto bail;
 566         }
 567         wc.wr_id = wqe->wr_id;
 568         qp->r_sge.sge = wqe->sg_list[0];
 569         qp->r_sge.sg_list = wqe->sg_list + 1;
 570         qp->r_sge.num_sge = wqe->num_sge;
 571         if (++rq->tail >= rq->size)
 572                 rq->tail = 0;
 573         if (srq && srq->ibsrq.event_handler) {
 574                 u32 n;
 575
 576                 if (rq->head < rq->tail)
 577                         n = rq->size + rq->head - rq->tail;
 578                 else
 579                         n = rq->head - rq->tail;
 580                 if (n < srq->limit) {
 581                         struct ib_event ev;
 582
 583                         srq->limit = 0;
 584                         spin_unlock_irqrestore(&rq->lock, flags);
 585                         ev.device = qp->ibqp.device;
 586                         ev.element.srq = qp->ibqp.srq;
 587                         ev.event = IB_EVENT_SRQ_LIMIT_REACHED;
 588                         srq->ibsrq.event_handler(&ev,
 589                                                  srq->ibsrq.srq_context);
 590                 } else
 591                         spin_unlock_irqrestore(&rq->lock, flags);
 592         } else
 593                 spin_unlock_irqrestore(&rq->lock, flags);
 594         if (has_grh) {
 595                 ipath_copy_sge(&qp->r_sge, &hdr->u.l.grh,
 596                                sizeof(struct ib_grh));
 597                 wc.wc_flags |= IB_WC_GRH;
 598         } else
 599                 ipath_skip_sge(&qp->r_sge, sizeof(struct ib_grh));
 600         ipath_copy_sge(&qp->r_sge, data,
 601                        wc.byte_len - sizeof(struct ib_grh));
 602         wc.status = IB_WC_SUCCESS;
 603         wc.opcode = IB_WC_RECV;
 604         wc.vendor_err = 0;
 605         wc.qp_num = qp->ibqp.qp_num;
 606         wc.src_qp = src_qp;
 607         /* XXX do we know which pkey matched? Only needed for GSI. */
 608         wc.pkey_index = 0;
 609         wc.slid = be16_to_cpu(hdr->lrh[3]);
 610         wc.sl = (be16_to_cpu(hdr->lrh[0]) >> 4) & 0xF;
 611         dlid = be16_to_cpu(hdr->lrh[1]);
 612         /*
 613          * Save the LMC lower bits if the destination LID is a unicast LID.
 614          */
 615         wc.dlid_path_bits = dlid >= IPS_MULTICAST_LID_BASE ? 0 :
 616                 dlid & ((1 << (dev->mkeyprot_resv_lmc & 7)) - 1);
 617         /* Signal completion event if the solicited bit is set. */
 618         ipath_cq_enter(to_icq(qp->ibqp.recv_cq), &wc,
 619                        (ohdr->bth[0] &
 620                         __constant_cpu_to_be32(1 << 23)) != 0);
 621
 622 bail:;
 623 }