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
  61         qp = qib_lookup_qpn(ibp, swqe->wr.wr.ud.remote_qpn);
  62         if (!qp) {
  63                 ibp->n_pkt_drops++;
  64                 return;
  65         }
  66         if (qp->ibqp.qp_type != sqp->ibqp.qp_type ||
  67             !(ib_qib_state_ops[qp->state] & QIB_PROCESS_RECV_OK)) {
  68                 ibp->n_pkt_drops++;
  69                 goto drop;
  70         }
  71
  72         ah_attr = &to_iah(swqe->wr.wr.ud.ah)->attr;
  73         ppd = ppd_from_ibp(ibp);
  74
  75         if (qp->ibqp.qp_num > 1) {
  76                 u16 pkey1;
  77                 u16 pkey2;
  78                 u16 lid;
  79
  80                 pkey1 = qib_get_pkey(ibp, sqp->s_pkey_index);
  81                 pkey2 = qib_get_pkey(ibp, qp->s_pkey_index);
  82                 if (unlikely(!qib_pkey_ok(pkey1, pkey2))) {
  83                         lid = ppd->lid | (ah_attr->src_path_bits &
  84                                           ((1 << ppd->lmc) - 1));
  85                         qib_bad_pqkey(ibp, IB_NOTICE_TRAP_BAD_PKEY, pkey1,
  86                                       ah_attr->sl,
  87                                       sqp->ibqp.qp_num, qp->ibqp.qp_num,
  88                                       cpu_to_be16(lid),
  89                                       cpu_to_be16(ah_attr->dlid));
  90                         goto drop;
  91                 }
  92         }
  93
  94         /*
  95          * Check that the qkey matches (except for QP0, see 9.6.1.4.1).
  96          * Qkeys with the high order bit set mean use the
  97          * qkey from the QP context instead of the WR (see 10.2.5).
  98          */
  99         if (qp->ibqp.qp_num) {
 100                 u32 qkey;
 101
 102                 qkey = (int)swqe->wr.wr.ud.remote_qkey < 0 ?
 103                         sqp->qkey : swqe->wr.wr.ud.remote_qkey;
 104                 if (unlikely(qkey != qp->qkey)) {
 105                         u16 lid;
 106
 107                         lid = ppd->lid | (ah_attr->src_path_bits &
 108                                           ((1 << ppd->lmc) - 1));
 109                         qib_bad_pqkey(ibp, IB_NOTICE_TRAP_BAD_QKEY, qkey,
 110                                       ah_attr->sl,
 111                                       sqp->ibqp.qp_num, qp->ibqp.qp_num,
 112                                       cpu_to_be16(lid),
 113                                       cpu_to_be16(ah_attr->dlid));
 114                         goto drop;
 115                 }
 116         }
 117
 118         /*
 119          * A GRH is expected to precede the data even if not
 120          * present on the wire.
 121          */
 122         length = swqe->length;
 123         memset(&wc, 0, sizeof wc);
 124         wc.byte_len = length + sizeof(struct ib_grh);
 125
 126         if (swqe->wr.opcode == IB_WR_SEND_WITH_IMM) {
 127                 wc.wc_flags = IB_WC_WITH_IMM;
 128                 wc.ex.imm_data = swqe->wr.ex.imm_data;
 129         }
 130
 131         spin_lock_irqsave(&qp->r_lock, flags);
 132
 133         /*
 134          * Get the next work request entry to find where to put the data.
 135          */
 136         if (qp->r_flags & QIB_R_REUSE_SGE)
 137                 qp->r_flags &= ~QIB_R_REUSE_SGE;
 138         else {
 139                 int ret;
 140
 141                 ret = qib_get_rwqe(qp, 0);
 142                 if (ret < 0) {
 143                         qib_rc_error(qp, IB_WC_LOC_QP_OP_ERR);
 144                         goto bail_unlock;
 145                 }
 146                 if (!ret) {
 147                         if (qp->ibqp.qp_num == 0)
 148                                 ibp->n_vl15_dropped++;
 149                         goto bail_unlock;
 150                 }
 151         }
 152         /* Silently drop packets which are too big. */
 153         if (unlikely(wc.byte_len > qp->r_len)) {
 154                 qp->r_flags |= QIB_R_REUSE_SGE;
 155                 ibp->n_pkt_drops++;
 156                 goto bail_unlock;
 157         }
 158
 159         if (ah_attr->ah_flags & IB_AH_GRH) {
 160                 qib_copy_sge(&qp->r_sge, &ah_attr->grh,
 161                              sizeof(struct ib_grh), 1);
 162                 wc.wc_flags |= IB_WC_GRH;
 163         } else
 164                 qib_skip_sge(&qp->r_sge, sizeof(struct ib_grh), 1);
 165         ssge.sg_list = swqe->sg_list + 1;
 166         ssge.sge = *swqe->sg_list;
 167         ssge.num_sge = swqe->wr.num_sge;
 168         sge = &ssge.sge;
 169         while (length) {
 170                 u32 len = sge->length;
 171
 172                 if (len > length)
 173                         len = length;
 174                 if (len > sge->sge_length)
 175                         len = sge->sge_length;
 176                 BUG_ON(len == 0);
 177                 qib_copy_sge(&qp->r_sge, sge->vaddr, len, 1);
 178                 sge->vaddr += len;
 179                 sge->length -= len;
 180                 sge->sge_length -= len;
 181                 if (sge->sge_length == 0) {
 182                         if (--ssge.num_sge)
 183                                 *sge = *ssge.sg_list++;
 184                 } else if (sge->length == 0 && sge->mr->lkey) {
 185                         if (++sge->n >= QIB_SEGSZ) {
 186                                 if (++sge->m >= sge->mr->mapsz)
 187                                         break;
 188                                 sge->n = 0;
 189                         }
 190                         sge->vaddr =
 191                                 sge->mr->map[sge->m]->segs[sge->n].vaddr;
 192                         sge->length =
 193                                 sge->mr->map[sge->m]->segs[sge->n].length;
 194                 }
 195                 length -= len;
 196         }
 197         while (qp->r_sge.num_sge) {
 198                 atomic_dec(&qp->r_sge.sge.mr->refcount);
 199                 if (--qp->r_sge.num_sge)
 200                         qp->r_sge.sge = *qp->r_sge.sg_list++;
 201         }
 202         if (!test_and_clear_bit(QIB_R_WRID_VALID, &qp->r_aflags))
 203                 goto bail_unlock;
 204         wc.wr_id = qp->r_wr_id;
 205         wc.status = IB_WC_SUCCESS;
 206         wc.opcode = IB_WC_RECV;
 207         wc.qp = &qp->ibqp;
 208         wc.src_qp = sqp->ibqp.qp_num;
 209         wc.pkey_index = qp->ibqp.qp_type == IB_QPT_GSI ?
 210                 swqe->wr.wr.ud.pkey_index : 0;
 211         wc.slid = ppd->lid | (ah_attr->src_path_bits & ((1 << ppd->lmc) - 1));
 212         wc.sl = ah_attr->sl;
 213         wc.dlid_path_bits = ah_attr->dlid & ((1 << ppd->lmc) - 1);
 214         wc.port_num = qp->port_num;
 215         /* Signal completion event if the solicited bit is set. */
 216         qib_cq_enter(to_icq(qp->ibqp.recv_cq), &wc,
 217                      swqe->wr.send_flags & IB_SEND_SOLICITED);
 218         ibp->n_loop_pkts++;
 219 bail_unlock:
 220         spin_unlock_irqrestore(&qp->r_lock, flags);
 221 drop:
 222         if (atomic_dec_and_test(&qp->refcount))
 223                 wake_up(&qp->wait);
 224 }
 225
 226 /**
 227  * qib_make_ud_req - construct a UD request packet
 228  * @qp: the QP
 229  *
 230  * Return 1 if constructed; otherwise, return 0.
 231  */
 232 int qib_make_ud_req(struct qib_qp *qp)
 233 {
 234         struct qib_other_headers *ohdr;
 235         struct ib_ah_attr *ah_attr;
 236         struct qib_pportdata *ppd;
 237         struct qib_ibport *ibp;
 238         struct qib_swqe *wqe;
 239         unsigned long flags;
 240         u32 nwords;
 241         u32 extra_bytes;
 242         u32 bth0;
 243         u16 lrh0;
 244         u16 lid;
 245         int ret = 0;
 246         int next_cur;
 247
 248         spin_lock_irqsave(&qp->s_lock, flags);
 249
 250         if (!(ib_qib_state_ops[qp->state] & QIB_PROCESS_NEXT_SEND_OK)) {
 251                 if (!(ib_qib_state_ops[qp->state] & QIB_FLUSH_SEND))
 252                         goto bail;
 253                 /* We are in the error state, flush the work request. */
 254                 if (qp->s_last == qp->s_head)
 255                         goto bail;
 256                 /* If DMAs are in progress, we can't flush immediately. */
 257                 if (atomic_read(&qp->s_dma_busy)) {
 258                         qp->s_flags |= QIB_S_WAIT_DMA;
 259                         goto bail;
 260                 }
 261                 wqe = get_swqe_ptr(qp, qp->s_last);
 262                 qib_send_complete(qp, wqe, IB_WC_WR_FLUSH_ERR);
 263                 goto done;
 264         }
 265
 266         if (qp->s_cur == qp->s_head)
 267                 goto bail;
 268
 269         wqe = get_swqe_ptr(qp, qp->s_cur);
 270         next_cur = qp->s_cur + 1;
 271         if (next_cur >= qp->s_size)
 272                 next_cur = 0;
 273
 274         /* Construct the header. */
 275         ibp = to_iport(qp->ibqp.device, qp->port_num);
 276         ppd = ppd_from_ibp(ibp);
 277         ah_attr = &to_iah(wqe->wr.wr.ud.ah)->attr;
 278         if (ah_attr->dlid >= QIB_MULTICAST_LID_BASE) {
 279                 if (ah_attr->dlid != QIB_PERMISSIVE_LID)
 280                         ibp->n_multicast_xmit++;
 281                 else
 282                         ibp->n_unicast_xmit++;
 283         } else {
 284                 ibp->n_unicast_xmit++;
 285                 lid = ah_attr->dlid & ~((1 << ppd->lmc) - 1);
 286                 if (unlikely(lid == ppd->lid)) {
 287                         /*
 288                          * If DMAs are in progress, we can't generate
 289                          * a completion for the loopback packet since
 290                          * it would be out of order.
 291                          * XXX Instead of waiting, we could queue a
 292                          * zero length descriptor so we get a callback.
 293                          */
 294                         if (atomic_read(&qp->s_dma_busy)) {
 295                                 qp->s_flags |= QIB_S_WAIT_DMA;
 296                                 goto bail;
 297                         }
 298                         qp->s_cur = next_cur;
 299                         spin_unlock_irqrestore(&qp->s_lock, flags);
 300                         qib_ud_loopback(qp, wqe);
 301                         spin_lock_irqsave(&qp->s_lock, flags);
 302                         qib_send_complete(qp, wqe, IB_WC_SUCCESS);
 303                         goto done;
 304                 }
 305         }
 306
 307         qp->s_cur = next_cur;
 308         extra_bytes = -wqe->length & 3;
 309         nwords = (wqe->length + extra_bytes) >> 2;
 310
 311         /* header size in 32-bit words LRH+BTH+DETH = (8+12+8)/4. */
 312         qp->s_hdrwords = 7;
 313         qp->s_cur_size = wqe->length;
 314         qp->s_cur_sge = &qp->s_sge;
 315         qp->s_srate = ah_attr->static_rate;
 316         qp->s_wqe = wqe;
 317         qp->s_sge.sge = wqe->sg_list[0];
 318         qp->s_sge.sg_list = wqe->sg_list + 1;
 319         qp->s_sge.num_sge = wqe->wr.num_sge;
 320         qp->s_sge.total_len = wqe->length;
 321
 322         if (ah_attr->ah_flags & IB_AH_GRH) {
 323                 /* Header size in 32-bit words. */
 324                 qp->s_hdrwords += qib_make_grh(ibp, &qp->s_hdr.u.l.grh,
 325                                                &ah_attr->grh,
 326                                                qp->s_hdrwords, nwords);
 327                 lrh0 = QIB_LRH_GRH;
 328                 ohdr = &qp->s_hdr.u.l.oth;
 329                 /*
 330                  * Don't worry about sending to locally attached multicast
 331                  * QPs.  It is unspecified by the spec. what happens.
 332                  */
 333         } else {
 334                 /* Header size in 32-bit words. */
 335                 lrh0 = QIB_LRH_BTH;
 336                 ohdr = &qp->s_hdr.u.oth;
 337         }
 338         if (wqe->wr.opcode == IB_WR_SEND_WITH_IMM) {
 339                 qp->s_hdrwords++;
 340                 ohdr->u.ud.imm_data = wqe->wr.ex.imm_data;
 341                 bth0 = IB_OPCODE_UD_SEND_ONLY_WITH_IMMEDIATE << 24;
 342         } else
 343                 bth0 = IB_OPCODE_UD_SEND_ONLY << 24;
 344         lrh0 |= ah_attr->sl << 4;
 345         if (qp->ibqp.qp_type == IB_QPT_SMI)
 346                 lrh0 |= 0xF000; /* Set VL (see ch. 13.5.3.1) */
 347         else
 348                 lrh0 |= ibp->sl_to_vl[ah_attr->sl] << 12;
 349         qp->s_hdr.lrh[0] = cpu_to_be16(lrh0);
 350         qp->s_hdr.lrh[1] = cpu_to_be16(ah_attr->dlid);  /* DEST LID */
 351         qp->s_hdr.lrh[2] = cpu_to_be16(qp->s_hdrwords + nwords + SIZE_OF_CRC);
 352         lid = ppd->lid;
 353         if (lid) {
 354                 lid |= ah_attr->src_path_bits & ((1 << ppd->lmc) - 1);
 355                 qp->s_hdr.lrh[3] = cpu_to_be16(lid);
 356         } else
 357                 qp->s_hdr.lrh[3] = IB_LID_PERMISSIVE;
 358         if (wqe->wr.send_flags & IB_SEND_SOLICITED)
 359                 bth0 |= IB_BTH_SOLICITED;
 360         bth0 |= extra_bytes << 20;
 361         bth0 |= qp->ibqp.qp_type == IB_QPT_SMI ? QIB_DEFAULT_P_KEY :
 362                 qib_get_pkey(ibp, qp->ibqp.qp_type == IB_QPT_GSI ?
 363                              wqe->wr.wr.ud.pkey_index : qp->s_pkey_index);
 364         ohdr->bth[0] = cpu_to_be32(bth0);
 365         /*
 366          * Use the multicast QP if the destination LID is a multicast LID.
 367          */
 368         ohdr->bth[1] = ah_attr->dlid >= QIB_MULTICAST_LID_BASE &&
 369                 ah_attr->dlid != QIB_PERMISSIVE_LID ?
 370                 cpu_to_be32(QIB_MULTICAST_QPN) :
 371                 cpu_to_be32(wqe->wr.wr.ud.remote_qpn);
 372         ohdr->bth[2] = cpu_to_be32(qp->s_next_psn++ & QIB_PSN_MASK);
 373         /*
 374          * Qkeys with the high order bit set mean use the
 375          * qkey from the QP context instead of the WR (see 10.2.5).
 376          */
 377         ohdr->u.ud.deth[0] = cpu_to_be32((int)wqe->wr.wr.ud.remote_qkey < 0 ?
 378                                          qp->qkey : wqe->wr.wr.ud.remote_qkey);
 379         ohdr->u.ud.deth[1] = cpu_to_be32(qp->ibqp.qp_num);
 380
 381 done:
 382         ret = 1;
 383         goto unlock;
 384
 385 bail:
 386         qp->s_flags &= ~QIB_S_BUSY;
 387 unlock:
 388         spin_unlock_irqrestore(&qp->s_lock, flags);
 389         return ret;
 390 }
 391
 392 static unsigned qib_lookup_pkey(struct qib_ibport *ibp, u16 pkey)
 393 {
 394         struct qib_pportdata *ppd = ppd_from_ibp(ibp);
 395         struct qib_devdata *dd = ppd->dd;
 396         unsigned ctxt = ppd->hw_pidx;
 397         unsigned i;
 398
 399         pkey &= 0x7fff; /* remove limited/full membership bit */
 400
 401         for (i = 0; i < ARRAY_SIZE(dd->rcd[ctxt]->pkeys); ++i)
 402                 if ((dd->rcd[ctxt]->pkeys[i] & 0x7fff) == pkey)
 403                         return i;
 404
 405         /*
 406          * Should not get here, this means hardware failed to validate pkeys.
 407          * Punt and return index 0.
 408          */
 409         return 0;
 410 }
 411
 412 /**
 413  * qib_ud_rcv - receive an incoming UD packet
 414  * @ibp: the port the packet came in on
 415  * @hdr: the packet header
 416  * @has_grh: true if the packet has a GRH
 417  * @data: the packet data
 418  * @tlen: the packet length
 419  * @qp: the QP the packet came on
 420  *
 421  * This is called from qib_qp_rcv() to process an incoming UD packet
 422  * for the given QP.
 423  * Called at interrupt level.
 424  */
 425 void qib_ud_rcv(struct qib_ibport *ibp, struct qib_ib_header *hdr,
 426                 int has_grh, void *data, u32 tlen, struct qib_qp *qp)
 427 {
 428         struct qib_other_headers *ohdr;
 429         int opcode;
 430         u32 hdrsize;
 431         u32 pad;
 432         struct ib_wc wc;
 433         u32 qkey;
 434         u32 src_qp;
 435         u16 dlid;
 436
 437         /* Check for GRH */
 438         if (!has_grh) {
 439                 ohdr = &hdr->u.oth;
 440                 hdrsize = 8 + 12 + 8;   /* LRH + BTH + DETH */
 441         } else {
 442                 ohdr = &hdr->u.l.oth;
 443                 hdrsize = 8 + 40 + 12 + 8; /* LRH + GRH + BTH + DETH */
 444         }
 445         qkey = be32_to_cpu(ohdr->u.ud.deth[0]);
 446         src_qp = be32_to_cpu(ohdr->u.ud.deth[1]) & QIB_QPN_MASK;
 447
 448         /*
 449          * Get the number of bytes the message was padded by
 450          * and drop incomplete packets.
 451          */
 452         pad = (be32_to_cpu(ohdr->bth[0]) >> 20) & 3;
 453         if (unlikely(tlen < (hdrsize + pad + 4)))
 454                 goto drop;
 455
 456         tlen -= hdrsize + pad + 4;
 457
 458         /*
 459          * Check that the permissive LID is only used on QP0
 460          * and the QKEY matches (see 9.6.1.4.1 and 9.6.1.5.1).
 461          */
 462         if (qp->ibqp.qp_num) {
 463                 if (unlikely(hdr->lrh[1] == IB_LID_PERMISSIVE ||
 464                              hdr->lrh[3] == IB_LID_PERMISSIVE))
 465                         goto drop;
 466                 if (qp->ibqp.qp_num > 1) {
 467                         u16 pkey1, pkey2;
 468
 469                         pkey1 = be32_to_cpu(ohdr->bth[0]);
 470                         pkey2 = qib_get_pkey(ibp, qp->s_pkey_index);
 471                         if (unlikely(!qib_pkey_ok(pkey1, pkey2))) {
 472                                 qib_bad_pqkey(ibp, IB_NOTICE_TRAP_BAD_PKEY,
 473                                               pkey1,
 474                                               (be16_to_cpu(hdr->lrh[0]) >> 4) &
 475                                                 0xF,
 476                                               src_qp, qp->ibqp.qp_num,
 477                                               hdr->lrh[3], hdr->lrh[1]);
 478                                 return;
 479                         }
 480                 }
 481                 if (unlikely(qkey != qp->qkey)) {
 482                         qib_bad_pqkey(ibp, IB_NOTICE_TRAP_BAD_QKEY, qkey,
 483                                       (be16_to_cpu(hdr->lrh[0]) >> 4) & 0xF,
 484                                       src_qp, qp->ibqp.qp_num,
 485                                       hdr->lrh[3], hdr->lrh[1]);
 486                         return;
 487                 }
 488                 /* Drop invalid MAD packets (see 13.5.3.1). */
 489                 if (unlikely(qp->ibqp.qp_num == 1 &&
 490                              (tlen != 256 ||
 491                               (be16_to_cpu(hdr->lrh[0]) >> 12) == 15)))
 492                         goto drop;
 493         } else {
 494                 struct ib_smp *smp;
 495
 496                 /* Drop invalid MAD packets (see 13.5.3.1). */
 497                 if (tlen != 256 || (be16_to_cpu(hdr->lrh[0]) >> 12) != 15)
 498                         goto drop;
 499                 smp = (struct ib_smp *) data;
 500                 if ((hdr->lrh[1] == IB_LID_PERMISSIVE ||
 501                      hdr->lrh[3] == IB_LID_PERMISSIVE) &&
 502                     smp->mgmt_class != IB_MGMT_CLASS_SUBN_DIRECTED_ROUTE)
 503                         goto drop;
 504         }
 505
 506         /*
 507          * The opcode is in the low byte when its in network order
 508          * (top byte when in host order).
 509          */
 510         opcode = be32_to_cpu(ohdr->bth[0]) >> 24;
 511         if (qp->ibqp.qp_num > 1 &&
 512             opcode == IB_OPCODE_UD_SEND_ONLY_WITH_IMMEDIATE) {
 513                 wc.ex.imm_data = ohdr->u.ud.imm_data;
 514                 wc.wc_flags = IB_WC_WITH_IMM;
 515                 tlen -= sizeof(u32);
 516         } else if (opcode == IB_OPCODE_UD_SEND_ONLY) {
 517                 wc.ex.imm_data = 0;
 518                 wc.wc_flags = 0;
 519         } else
 520                 goto drop;
 521
 522         /*
 523          * A GRH is expected to precede the data even if not
 524          * present on the wire.
 525          */
 526         wc.byte_len = tlen + sizeof(struct ib_grh);
 527
 528         /*
 529          * Get the next work request entry to find where to put the data.
 530          */
 531         if (qp->r_flags & QIB_R_REUSE_SGE)
 532                 qp->r_flags &= ~QIB_R_REUSE_SGE;
 533         else {
 534                 int ret;
 535
 536                 ret = qib_get_rwqe(qp, 0);
 537                 if (ret < 0) {
 538                         qib_rc_error(qp, IB_WC_LOC_QP_OP_ERR);
 539                         return;
 540                 }
 541                 if (!ret) {
 542                         if (qp->ibqp.qp_num == 0)
 543                                 ibp->n_vl15_dropped++;
 544                         return;
 545                 }
 546         }
 547         /* Silently drop packets which are too big. */
 548         if (unlikely(wc.byte_len > qp->r_len)) {
 549                 qp->r_flags |= QIB_R_REUSE_SGE;
 550                 goto drop;
 551         }
 552         if (has_grh) {
 553                 qib_copy_sge(&qp->r_sge, &hdr->u.l.grh,
 554                              sizeof(struct ib_grh), 1);
 555                 wc.wc_flags |= IB_WC_GRH;
 556         } else
 557                 qib_skip_sge(&qp->r_sge, sizeof(struct ib_grh), 1);
 558         qib_copy_sge(&qp->r_sge, data, wc.byte_len - sizeof(struct ib_grh), 1);
 559         while (qp->r_sge.num_sge) {
 560                 atomic_dec(&qp->r_sge.sge.mr->refcount);
 561                 if (--qp->r_sge.num_sge)
 562                         qp->r_sge.sge = *qp->r_sge.sg_list++;
 563         }
 564         if (!test_and_clear_bit(QIB_R_WRID_VALID, &qp->r_aflags))
 565                 return;
 566         wc.wr_id = qp->r_wr_id;
 567         wc.status = IB_WC_SUCCESS;
 568         wc.opcode = IB_WC_RECV;
 569         wc.vendor_err = 0;
 570         wc.qp = &qp->ibqp;
 571         wc.src_qp = src_qp;
 572         wc.pkey_index = qp->ibqp.qp_type == IB_QPT_GSI ?
 573                 qib_lookup_pkey(ibp, be32_to_cpu(ohdr->bth[0])) : 0;
 574         wc.slid = be16_to_cpu(hdr->lrh[3]);
 575         wc.sl = (be16_to_cpu(hdr->lrh[0]) >> 4) & 0xF;
 576         dlid = be16_to_cpu(hdr->lrh[1]);
 577         /*
 578          * Save the LMC lower bits if the destination LID is a unicast LID.
 579          */
 580         wc.dlid_path_bits = dlid >= QIB_MULTICAST_LID_BASE ? 0 :
 581                 dlid & ((1 << ppd_from_ibp(ibp)->lmc) - 1);
 582         wc.port_num = qp->port_num;
 583         /* Signal completion event if the solicited bit is set. */
 584         qib_cq_enter(to_icq(qp->ibqp.recv_cq), &wc,
 585                      (ohdr->bth[0] &
 586                         cpu_to_be32(IB_BTH_SOLICITED)) != 0);
 587         return;
 588
 589 drop:
 590         ibp->n_pkt_drops++;
 591 }