drivers/infiniband/hw/qib/qib_ud.c

   1 /*
   2  * Copyright (c) 2006, 2007, 2008, 2009 QLogic Corporation. All rights reserved.
   3  * Copyright (c) 2005, 2006 PathScale, Inc. All rights reserved.
   4  *
   5  * This software is available to you under a choice of one of two
   6  * licenses.  You may choose to be licensed under the terms of the GNU
   7  * General Public License (GPL) Version 2, available from the file
   8  * COPYING in the main directory of this source tree, or the
   9  * OpenIB.org BSD license below:
  10  *
  11  *     Redistribution and use in source and binary forms, with or
  12  *     without modification, are permitted provided that the following
  13  *     conditions are met:
  14  *
  15  *      - Redistributions of source code must retain the above
  16  *        copyright notice, this list of conditions and the following
  17  *        disclaimer.
  18  *
  19  *      - Redistributions in binary form must reproduce the above
  20  *        copyright notice, this list of conditions and the following
  21  *        disclaimer in the documentation and/or other materials
  22  *        provided with the distribution.
  23  *
  24  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  25  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  26  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  27  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  28  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  29  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  30  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  31  * SOFTWARE.
  32  */
  33
  34 #include <rdma/ib_smi.h>
  35
  36 #include "qib.h"
  37 #include "qib_mad.h"
  38
  39 /**
  40  * qib_ud_loopback - handle send on loopback QPs
  41  * @sqp: the sending QP
  42  * @swqe: the send work request
  43  *
  44  * This is called from qib_make_ud_req() to forward a WQE addressed
  45  * to the same HCA.
  46  * Note that the receive interrupt handler may be calling qib_ud_rcv()
  47  * while this is being called.
  48  */
  49 static void qib_ud_loopback(struct qib_qp *sqp, struct qib_swqe *swqe)
  50 {
  51         struct qib_ibport *ibp = to_iport(sqp->ibqp.device, sqp->port_num);
  52         struct qib_pportdata *ppd;
  53         struct qib_qp *qp;
  54         struct ib_ah_attr *ah_attr;
  55         unsigned long flags;
  56         struct qib_sge_state ssge;
  57         struct qib_sge *sge;
  58         struct ib_wc wc;
  59         u32 length;
  60         enum ib_qp_type sqptype, dqptype;
  61
  62         qp = qib_lookup_qpn(ibp, swqe->wr.wr.ud.remote_qpn);
  63         if (!qp) {
  64                 ibp->n_pkt_drops++;
  65                 return;
  66         }
  67
  68         sqptype = sqp->ibqp.qp_type == IB_QPT_GSI ?
  69                         IB_QPT_UD : sqp->ibqp.qp_type;
  70         dqptype = qp->ibqp.qp_type == IB_QPT_GSI ?
  71                         IB_QPT_UD : qp->ibqp.qp_type;
  72
  73         if (dqptype != sqptype ||
  74             !(ib_qib_state_ops[qp->state] & QIB_PROCESS_RECV_OK)) {
  75                 ibp->n_pkt_drops++;
  76                 goto drop;
  77         }
  78
  79         ah_attr = &to_iah(swqe->wr.wr.ud.ah)->attr;
  80         ppd = ppd_from_ibp(ibp);
  81
  82         if (qp->ibqp.qp_num > 1) {
  83                 u16 pkey1;
  84                 u16 pkey2;
  85                 u16 lid;
  86
  87                 pkey1 = qib_get_pkey(ibp, sqp->s_pkey_index);
  88                 pkey2 = qib_get_pkey(ibp, qp->s_pkey_index);
  89                 if (unlikely(!qib_pkey_ok(pkey1, pkey2))) {
  90                         lid = ppd->lid | (ah_attr->src_path_bits &
  91                                           ((1 << ppd->lmc) - 1));
  92                         qib_bad_pqkey(ibp, IB_NOTICE_TRAP_BAD_PKEY, pkey1,
  93                                       ah_attr->sl,
  94                                       sqp->ibqp.qp_num, qp->ibqp.qp_num,
  95                                       cpu_to_be16(lid),
  96                                       cpu_to_be16(ah_attr->dlid));
  97                         goto drop;
  98                 }
  99         }
 100
 101         /*
 102          * Check that the qkey matches (except for QP0, see 9.6.1.4.1).
 103          * Qkeys with the high order bit set mean use the
 104          * qkey from the QP context instead of the WR (see 10.2.5).
 105          */
 106         if (qp->ibqp.qp_num) {
 107                 u32 qkey;
 108
 109                 qkey = (int)swqe->wr.wr.ud.remote_qkey < 0 ?
 110                         sqp->qkey : swqe->wr.wr.ud.remote_qkey;
 111                 if (unlikely(qkey != qp->qkey)) {
 112                         u16 lid;
 113
 114                         lid = ppd->lid | (ah_attr->src_path_bits &
 115                                           ((1 << ppd->lmc) - 1));
 116                         qib_bad_pqkey(ibp, IB_NOTICE_TRAP_BAD_QKEY, qkey,
 117                                       ah_attr->sl,
 118                                       sqp->ibqp.qp_num, qp->ibqp.qp_num,
 119                                       cpu_to_be16(lid),
 120                                       cpu_to_be16(ah_attr->dlid));
 121                         goto drop;
 122                 }
 123         }
 124
 125         /*
 126          * A GRH is expected to precede the data even if not
 127          * present on the wire.
 128          */
 129         length = swqe->length;
 130         memset(&wc, 0, sizeof wc);
 131         wc.byte_len = length + sizeof(struct ib_grh);
 132
 133         if (swqe->wr.opcode == IB_WR_SEND_WITH_IMM) {
 134                 wc.wc_flags = IB_WC_WITH_IMM;
 135                 wc.ex.imm_data = swqe->wr.ex.imm_data;
 136         }
 137
 138         spin_lock_irqsave(&qp->r_lock, flags);
 139
 140         /*
 141          * Get the next work request entry to find where to put the data.
 142          */
 143         if (qp->r_flags & QIB_R_REUSE_SGE)
 144                 qp->r_flags &= ~QIB_R_REUSE_SGE;
 145         else {
 146                 int ret;
 147
 148                 ret = qib_get_rwqe(qp, 0);
 149                 if (ret < 0) {
 150                         qib_rc_error(qp, IB_WC_LOC_QP_OP_ERR);
 151                         goto bail_unlock;
 152                 }
 153                 if (!ret) {
 154                         if (qp->ibqp.qp_num == 0)
 155                                 ibp->n_vl15_dropped++;
 156                         goto bail_unlock;
 157                 }
 158         }
 159         /* Silently drop packets which are too big. */
 160         if (unlikely(wc.byte_len > qp->r_len)) {
 161                 qp->r_flags |= QIB_R_REUSE_SGE;
 162                 ibp->n_pkt_drops++;
 163                 goto bail_unlock;
 164         }
 165
 166         if (ah_attr->ah_flags & IB_AH_GRH) {
 167                 qib_copy_sge(&qp->r_sge, &ah_attr->grh,
 168                              sizeof(struct ib_grh), 1);
 169                 wc.wc_flags |= IB_WC_GRH;
 170         } else
 171                 qib_skip_sge(&qp->r_sge, sizeof(struct ib_grh), 1);
 172         ssge.sg_list = swqe->sg_list + 1;
 173         ssge.sge = *swqe->sg_list;
 174         ssge.num_sge = swqe->wr.num_sge;
 175         sge = &ssge.sge;
 176         while (length) {
 177                 u32 len = sge->length;
 178
 179                 if (len > length)
 180                         len = length;
 181                 if (len > sge->sge_length)
 182                         len = sge->sge_length;
 183                 BUG_ON(len == 0);
 184                 qib_copy_sge(&qp->r_sge, sge->vaddr, len, 1);
 185                 sge->vaddr += len;
 186                 sge->length -= len;
 187                 sge->sge_length -= len;
 188                 if (sge->sge_length == 0) {
 189                         if (--ssge.num_sge)
 190                                 *sge = *ssge.sg_list++;
 191                 } else if (sge->length == 0 && sge->mr->lkey) {
 192                         if (++sge->n >= QIB_SEGSZ) {
 193                                 if (++sge->m >= sge->mr->mapsz)
 194                                         break;
 195                                 sge->n = 0;
 196                         }
 197                         sge->vaddr =
 198                                 sge->mr->map[sge->m]->segs[sge->n].vaddr;
 199                         sge->length =
 200                                 sge->mr->map[sge->m]->segs[sge->n].length;
 201                 }
 202                 length -= len;
 203         }
 204         qib_put_ss(&qp->r_sge);
 205         if (!test_and_clear_bit(QIB_R_WRID_VALID, &qp->r_aflags))
 206                 goto bail_unlock;
 207         wc.wr_id = qp->r_wr_id;
 208         wc.status = IB_WC_SUCCESS;
 209         wc.opcode = IB_WC_RECV;
 210         wc.qp = &qp->ibqp;
 211         wc.src_qp = sqp->ibqp.qp_num;
 212         wc.pkey_index = qp->ibqp.qp_type == IB_QPT_GSI ?
 213                 swqe->wr.wr.ud.pkey_index : 0;
 214         wc.slid = ppd->lid | (ah_attr->src_path_bits & ((1 << ppd->lmc) - 1));
 215         wc.sl = ah_attr->sl;
 216         wc.dlid_path_bits = ah_attr->dlid & ((1 << ppd->lmc) - 1);
 217         wc.port_num = qp->port_num;
 218         /* Signal completion event if the solicited bit is set. */
 219         qib_cq_enter(to_icq(qp->ibqp.recv_cq), &wc,
 220                      swqe->wr.send_flags & IB_SEND_SOLICITED);
 221         ibp->n_loop_pkts++;
 222 bail_unlock:
 223         spin_unlock_irqrestore(&qp->r_lock, flags);
 224 drop:
 225         if (atomic_dec_and_test(&qp->refcount))
 226                 wake_up(&qp->wait);
 227 }
 228
 229 /**
 230  * qib_make_ud_req - construct a UD request packet
 231  * @qp: the QP
 232  *
 233  * Return 1 if constructed; otherwise, return 0.
 234  */
 235 int qib_make_ud_req(struct qib_qp *qp)
 236 {
 237         struct qib_other_headers *ohdr;
 238         struct ib_ah_attr *ah_attr;
 239         struct qib_pportdata *ppd;
 240         struct qib_ibport *ibp;
 241         struct qib_swqe *wqe;
 242         unsigned long flags;
 243         u32 nwords;
 244         u32 extra_bytes;
 245         u32 bth0;
 246         u16 lrh0;
 247         u16 lid;
 248         int ret = 0;
 249         int next_cur;
 250
 251         spin_lock_irqsave(&qp->s_lock, flags);
 252
 253         if (!(ib_qib_state_ops[qp->state] & QIB_PROCESS_NEXT_SEND_OK)) {
 254                 if (!(ib_qib_state_ops[qp->state] & QIB_FLUSH_SEND))
 255                         goto bail;
 256                 /* We are in the error state, flush the work request. */
 257                 if (qp->s_last == qp->s_head)
 258                         goto bail;
 259                 /* If DMAs are in progress, we can't flush immediately. */
 260                 if (atomic_read(&qp->s_dma_busy)) {
 261                         qp->s_flags |= QIB_S_WAIT_DMA;
 262                         goto bail;
 263                 }
 264                 wqe = get_swqe_ptr(qp, qp->s_last);
 265                 qib_send_complete(qp, wqe, IB_WC_WR_FLUSH_ERR);
 266                 goto done;
 267         }
 268
 269         if (qp->s_cur == qp->s_head)
 270                 goto bail;
 271
 272         wqe = get_swqe_ptr(qp, qp->s_cur);
 273         next_cur = qp->s_cur + 1;
 274         if (next_cur >= qp->s_size)
 275                 next_cur = 0;
 276
 277         /* Construct the header. */
 278         ibp = to_iport(qp->ibqp.device, qp->port_num);
 279         ppd = ppd_from_ibp(ibp);
 280         ah_attr = &to_iah(wqe->wr.wr.ud.ah)->attr;
 281         if (ah_attr->dlid >= QIB_MULTICAST_LID_BASE) {
 282                 if (ah_attr->dlid != QIB_PERMISSIVE_LID)
 283                         ibp->n_multicast_xmit++;
 284                 else
 285                         ibp->n_unicast_xmit++;
 286         } else {
 287                 ibp->n_unicast_xmit++;
 288                 lid = ah_attr->dlid & ~((1 << ppd->lmc) - 1);
 289                 if (unlikely(lid == ppd->lid)) {
 290                         /*
 291                          * If DMAs are in progress, we can't generate
 292                          * a completion for the loopback packet since
 293                          * it would be out of order.
 294                          * XXX Instead of waiting, we could queue a
 295                          * zero length descriptor so we get a callback.
 296                          */
 297                         if (atomic_read(&qp->s_dma_busy)) {
 298                                 qp->s_flags |= QIB_S_WAIT_DMA;
 299                                 goto bail;
 300                         }
 301                         qp->s_cur = next_cur;
 302                         spin_unlock_irqrestore(&qp->s_lock, flags);
 303                         qib_ud_loopback(qp, wqe);
 304                         spin_lock_irqsave(&qp->s_lock, flags);
 305                         qib_send_complete(qp, wqe, IB_WC_SUCCESS);
 306                         goto done;
 307                 }
 308         }
 309
 310         qp->s_cur = next_cur;
 311         extra_bytes = -wqe->length & 3;
 312         nwords = (wqe->length + extra_bytes) >> 2;
 313
 314         /* header size in 32-bit words LRH+BTH+DETH = (8+12+8)/4. */
 315         qp->s_hdrwords = 7;
 316         qp->s_cur_size = wqe->length;
 317         qp->s_cur_sge = &qp->s_sge;
 318         qp->s_srate = ah_attr->static_rate;
 319         qp->s_wqe = wqe;
 320         qp->s_sge.sge = wqe->sg_list[0];
 321         qp->s_sge.sg_list = wqe->sg_list + 1;
 322         qp->s_sge.num_sge = wqe->wr.num_sge;
 323         qp->s_sge.total_len = wqe->length;
 324
 325         if (ah_attr->ah_flags & IB_AH_GRH) {
 326                 /* Header size in 32-bit words. */
 327                 qp->s_hdrwords += qib_make_grh(ibp, &qp->s_hdr->u.l.grh,
 328                                                &ah_attr->grh,
 329                                                qp->s_hdrwords, nwords);
 330                 lrh0 = QIB_LRH_GRH;
 331                 ohdr = &qp->s_hdr->u.l.oth;
 332                 /*
 333                  * Don't worry about sending to locally attached multicast
 334                  * QPs.  It is unspecified by the spec. what happens.
 335                  */
 336         } else {
 337                 /* Header size in 32-bit words. */
 338                 lrh0 = QIB_LRH_BTH;
 339                 ohdr = &qp->s_hdr->u.oth;
 340         }
 341         if (wqe->wr.opcode == IB_WR_SEND_WITH_IMM) {
 342                 qp->s_hdrwords++;
 343                 ohdr->u.ud.imm_data = wqe->wr.ex.imm_data;
 344                 bth0 = IB_OPCODE_UD_SEND_ONLY_WITH_IMMEDIATE << 24;
 345         } else
 346                 bth0 = IB_OPCODE_UD_SEND_ONLY << 24;
 347         lrh0 |= ah_attr->sl << 4;
 348         if (qp->ibqp.qp_type == IB_QPT_SMI)
 349                 lrh0 |= 0xF000; /* Set VL (see ch. 13.5.3.1) */
 350         else
 351                 lrh0 |= ibp->sl_to_vl[ah_attr->sl] << 12;
 352         qp->s_hdr->lrh[0] = cpu_to_be16(lrh0);
 353         qp->s_hdr->lrh[1] = cpu_to_be16(ah_attr->dlid);  /* DEST LID */
 354         qp->s_hdr->lrh[2] = cpu_to_be16(qp->s_hdrwords + nwords + SIZE_OF_CRC);
 355         lid = ppd->lid;
 356         if (lid) {
 357                 lid |= ah_attr->src_path_bits & ((1 << ppd->lmc) - 1);
 358                 qp->s_hdr->lrh[3] = cpu_to_be16(lid);
 359         } else
 360                 qp->s_hdr->lrh[3] = IB_LID_PERMISSIVE;
 361         if (wqe->wr.send_flags & IB_SEND_SOLICITED)
 362                 bth0 |= IB_BTH_SOLICITED;
 363         bth0 |= extra_bytes << 20;
 364         bth0 |= qp->ibqp.qp_type == IB_QPT_SMI ? QIB_DEFAULT_P_KEY :
 365                 qib_get_pkey(ibp, qp->ibqp.qp_type == IB_QPT_GSI ?
 366                              wqe->wr.wr.ud.pkey_index : qp->s_pkey_index);
 367         ohdr->bth[0] = cpu_to_be32(bth0);
 368         /*
 369          * Use the multicast QP if the destination LID is a multicast LID.
 370          */
 371         ohdr->bth[1] = ah_attr->dlid >= QIB_MULTICAST_LID_BASE &&
 372                 ah_attr->dlid != QIB_PERMISSIVE_LID ?
 373                 cpu_to_be32(QIB_MULTICAST_QPN) :
 374                 cpu_to_be32(wqe->wr.wr.ud.remote_qpn);
 375         ohdr->bth[2] = cpu_to_be32(qp->s_next_psn++ & QIB_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)wqe->wr.wr.ud.remote_qkey < 0 ?
 381                                          qp->qkey : wqe->wr.wr.ud.remote_qkey);
 382         ohdr->u.ud.deth[1] = cpu_to_be32(qp->ibqp.qp_num);
 383
 384 done:
 385         ret = 1;
 386         goto unlock;
 387
 388 bail:
 389         qp->s_flags &= ~QIB_S_BUSY;
 390 unlock:
 391         spin_unlock_irqrestore(&qp->s_lock, flags);
 392         return ret;
 393 }
 394
 395 static unsigned qib_lookup_pkey(struct qib_ibport *ibp, u16 pkey)
 396 {
 397         struct qib_pportdata *ppd = ppd_from_ibp(ibp);
 398         struct qib_devdata *dd = ppd->dd;
 399         unsigned ctxt = ppd->hw_pidx;
 400         unsigned i;
 401
 402         pkey &= 0x7fff; /* remove limited/full membership bit */
 403
 404         for (i = 0; i < ARRAY_SIZE(dd->rcd[ctxt]->pkeys); ++i)
 405                 if ((dd->rcd[ctxt]->pkeys[i] & 0x7fff) == pkey)
 406                         return i;
 407
 408         /*
 409          * Should not get here, this means hardware failed to validate pkeys.
 410          * Punt and return index 0.
 411          */
 412         return 0;
 413 }
 414
 415 /**
 416  * qib_ud_rcv - receive an incoming UD packet
 417  * @ibp: the port the packet came in on
 418  * @hdr: the packet header
 419  * @has_grh: true if the packet has a GRH
 420  * @data: the packet data
 421  * @tlen: the packet length
 422  * @qp: the QP the packet came on
 423  *
 424  * This is called from qib_qp_rcv() to process an incoming UD packet
 425  * for the given QP.
 426  * Called at interrupt level.
 427  */
 428 void qib_ud_rcv(struct qib_ibport *ibp, struct qib_ib_header *hdr,
 429                 int has_grh, void *data, u32 tlen, struct qib_qp *qp)
 430 {
 431         struct qib_other_headers *ohdr;
 432         int opcode;
 433         u32 hdrsize;
 434         u32 pad;
 435         struct ib_wc wc;
 436         u32 qkey;
 437         u32 src_qp;
 438         u16 dlid;
 439
 440         /* Check for GRH */
 441         if (!has_grh) {
 442                 ohdr = &hdr->u.oth;
 443                 hdrsize = 8 + 12 + 8;   /* LRH + BTH + DETH */
 444         } else {
 445                 ohdr = &hdr->u.l.oth;
 446                 hdrsize = 8 + 40 + 12 + 8; /* LRH + GRH + BTH + DETH */
 447         }
 448         qkey = be32_to_cpu(ohdr->u.ud.deth[0]);
 449         src_qp = be32_to_cpu(ohdr->u.ud.deth[1]) & QIB_QPN_MASK;
 450
 451         /*
 452          * Get the number of bytes the message was padded by
 453          * and drop incomplete packets.
 454          */
 455         pad = (be32_to_cpu(ohdr->bth[0]) >> 20) & 3;
 456         if (unlikely(tlen < (hdrsize + pad + 4)))
 457                 goto drop;
 458
 459         tlen -= hdrsize + pad + 4;
 460
 461         /*
 462          * Check that the permissive LID is only used on QP0
 463          * and the QKEY matches (see 9.6.1.4.1 and 9.6.1.5.1).
 464          */
 465         if (qp->ibqp.qp_num) {
 466                 if (unlikely(hdr->lrh[1] == IB_LID_PERMISSIVE ||
 467                              hdr->lrh[3] == IB_LID_PERMISSIVE))
 468                         goto drop;
 469                 if (qp->ibqp.qp_num > 1) {
 470                         u16 pkey1, pkey2;
 471
 472                         pkey1 = be32_to_cpu(ohdr->bth[0]);
 473                         pkey2 = qib_get_pkey(ibp, qp->s_pkey_index);
 474                         if (unlikely(!qib_pkey_ok(pkey1, pkey2))) {
 475                                 qib_bad_pqkey(ibp, IB_NOTICE_TRAP_BAD_PKEY,
 476                                               pkey1,
 477                                               (be16_to_cpu(hdr->lrh[0]) >> 4) &
 478                                                 0xF,
 479                                               src_qp, qp->ibqp.qp_num,
 480                                               hdr->lrh[3], hdr->lrh[1]);
 481                                 return;
 482                         }
 483                 }
 484                 if (unlikely(qkey != qp->qkey)) {
 485                         qib_bad_pqkey(ibp, IB_NOTICE_TRAP_BAD_QKEY, qkey,
 486                                       (be16_to_cpu(hdr->lrh[0]) >> 4) & 0xF,
 487                                       src_qp, qp->ibqp.qp_num,
 488                                       hdr->lrh[3], hdr->lrh[1]);
 489                         return;
 490                 }
 491                 /* Drop invalid MAD packets (see 13.5.3.1). */
 492                 if (unlikely(qp->ibqp.qp_num == 1 &&
 493                              (tlen != 256 ||
 494                               (be16_to_cpu(hdr->lrh[0]) >> 12) == 15)))
 495                         goto drop;
 496         } else {
 497                 struct ib_smp *smp;
 498
 499                 /* Drop invalid MAD packets (see 13.5.3.1). */
 500                 if (tlen != 256 || (be16_to_cpu(hdr->lrh[0]) >> 12) != 15)
 501                         goto drop;
 502                 smp = (struct ib_smp *) data;
 503                 if ((hdr->lrh[1] == IB_LID_PERMISSIVE ||
 504                      hdr->lrh[3] == IB_LID_PERMISSIVE) &&
 505                     smp->mgmt_class != IB_MGMT_CLASS_SUBN_DIRECTED_ROUTE)
 506                         goto drop;
 507         }
 508
 509         /*
 510          * The opcode is in the low byte when its in network order
 511          * (top byte when in host order).
 512          */
 513         opcode = be32_to_cpu(ohdr->bth[0]) >> 24;
 514         if (qp->ibqp.qp_num > 1 &&
 515             opcode == IB_OPCODE_UD_SEND_ONLY_WITH_IMMEDIATE) {
 516                 wc.ex.imm_data = ohdr->u.ud.imm_data;
 517                 wc.wc_flags = IB_WC_WITH_IMM;
 518                 tlen -= sizeof(u32);
 519         } else if (opcode == IB_OPCODE_UD_SEND_ONLY) {
 520                 wc.ex.imm_data = 0;
 521                 wc.wc_flags = 0;
 522         } else
 523                 goto drop;
 524
 525         /*
 526          * A GRH is expected to precede the data even if not
 527          * present on the wire.
 528          */
 529         wc.byte_len = tlen + sizeof(struct ib_grh);
 530
 531         /*
 532          * Get the next work request entry to find where to put the data.
 533          */
 534         if (qp->r_flags & QIB_R_REUSE_SGE)
 535                 qp->r_flags &= ~QIB_R_REUSE_SGE;
 536         else {
 537                 int ret;
 538
 539                 ret = qib_get_rwqe(qp, 0);
 540                 if (ret < 0) {
 541                         qib_rc_error(qp, IB_WC_LOC_QP_OP_ERR);
 542                         return;
 543                 }
 544                 if (!ret) {
 545                         if (qp->ibqp.qp_num == 0)
 546                                 ibp->n_vl15_dropped++;
 547                         return;
 548                 }
 549         }
 550         /* Silently drop packets which are too big. */
 551         if (unlikely(wc.byte_len > qp->r_len)) {
 552                 qp->r_flags |= QIB_R_REUSE_SGE;
 553                 goto drop;
 554         }
 555         if (has_grh) {
 556                 qib_copy_sge(&qp->r_sge, &hdr->u.l.grh,
 557                              sizeof(struct ib_grh), 1);
 558                 wc.wc_flags |= IB_WC_GRH;
 559         } else
 560                 qib_skip_sge(&qp->r_sge, sizeof(struct ib_grh), 1);
 561         qib_copy_sge(&qp->r_sge, data, wc.byte_len - sizeof(struct ib_grh), 1);
 562         qib_put_ss(&qp->r_sge);
 563         if (!test_and_clear_bit(QIB_R_WRID_VALID, &qp->r_aflags))
 564                 return;
 565         wc.wr_id = qp->r_wr_id;
 566         wc.status = IB_WC_SUCCESS;
 567         wc.opcode = IB_WC_RECV;
 568         wc.vendor_err = 0;
 569         wc.qp = &qp->ibqp;
 570         wc.src_qp = src_qp;
 571         wc.pkey_index = qp->ibqp.qp_type == IB_QPT_GSI ?
 572                 qib_lookup_pkey(ibp, be32_to_cpu(ohdr->bth[0])) : 0;
 573         wc.slid = be16_to_cpu(hdr->lrh[3]);
 574         wc.sl = (be16_to_cpu(hdr->lrh[0]) >> 4) & 0xF;
 575         dlid = be16_to_cpu(hdr->lrh[1]);
 576         /*
 577          * Save the LMC lower bits if the destination LID is a unicast LID.
 578          */
 579         wc.dlid_path_bits = dlid >= QIB_MULTICAST_LID_BASE ? 0 :
 580                 dlid & ((1 << ppd_from_ibp(ibp)->lmc) - 1);
 581         wc.port_num = qp->port_num;
 582         /* Signal completion event if the solicited bit is set. */
 583         qib_cq_enter(to_icq(qp->ibqp.recv_cq), &wc,
 584                      (ohdr->bth[0] &
 585                         cpu_to_be32(IB_BTH_SOLICITED)) != 0);
 586         return;
 587
 588 drop:
 589         ibp->n_pkt_drops++;
 590 }