drivers/infiniband/hw/ipath/ipath_rc.c

   1 /*
   2  * Copyright (c) 2006 QLogic, Inc. 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 "ipath_verbs.h"
  35 #include "ipath_kernel.h"
  36
  37 /* cut down ridiculously long IB macro names */
  38 #define OP(x) IB_OPCODE_RC_##x
  39
  40 /**
  41  * ipath_init_restart- initialize the qp->s_sge after a restart
  42  * @qp: the QP who's SGE we're restarting
  43  * @wqe: the work queue to initialize the QP's SGE from
  44  *
  45  * The QP s_lock should be held and interrupts disabled.
  46  */
  47 static void ipath_init_restart(struct ipath_qp *qp, struct ipath_swqe *wqe)
  48 {
  49         struct ipath_ibdev *dev;
  50         u32 len;
  51
  52         len = ((qp->s_psn - wqe->psn) & IPATH_PSN_MASK) *
  53                 ib_mtu_enum_to_int(qp->path_mtu);
  54         qp->s_sge.sge = wqe->sg_list[0];
  55         qp->s_sge.sg_list = wqe->sg_list + 1;
  56         qp->s_sge.num_sge = wqe->wr.num_sge;
  57         ipath_skip_sge(&qp->s_sge, len);
  58         qp->s_len = wqe->length - len;
  59         dev = to_idev(qp->ibqp.device);
  60         spin_lock(&dev->pending_lock);
  61         if (list_empty(&qp->timerwait))
  62                 list_add_tail(&qp->timerwait,
  63                               &dev->pending[dev->pending_index]);
  64         spin_unlock(&dev->pending_lock);
  65 }
  66
  67 /**
  68  * ipath_make_rc_ack - construct a response packet (ACK, NAK, or RDMA read)
  69  * @qp: a pointer to the QP
  70  * @ohdr: a pointer to the IB header being constructed
  71  * @pmtu: the path MTU
  72  *
  73  * Return bth0 if constructed; otherwise, return 0.
  74  * Note the QP s_lock must be held.
  75  */
  76 u32 ipath_make_rc_ack(struct ipath_qp *qp,
  77                       struct ipath_other_headers *ohdr,
  78                       u32 pmtu)
  79 {
  80         u32 hwords;
  81         u32 len;
  82         u32 bth0;
  83
  84         /* header size in 32-bit words LRH+BTH = (8+12)/4. */
  85         hwords = 5;
  86
  87         /*
  88          * Send a response.  Note that we are in the responder's
  89          * side of the QP context.
  90          */
  91         switch (qp->s_ack_state) {
  92         case OP(RDMA_READ_REQUEST):
  93                 qp->s_cur_sge = &qp->s_rdma_sge;
  94                 len = qp->s_rdma_len;
  95                 if (len > pmtu) {
  96                         len = pmtu;
  97                         qp->s_ack_state = OP(RDMA_READ_RESPONSE_FIRST);
  98                 } else
  99                         qp->s_ack_state = OP(RDMA_READ_RESPONSE_ONLY);
 100                 qp->s_rdma_len -= len;
 101                 bth0 = qp->s_ack_state << 24;
 102                 ohdr->u.aeth = ipath_compute_aeth(qp);
 103                 hwords++;
 104                 break;
 105
 106         case OP(RDMA_READ_RESPONSE_FIRST):
 107                 qp->s_ack_state = OP(RDMA_READ_RESPONSE_MIDDLE);
 108                 /* FALLTHROUGH */
 109         case OP(RDMA_READ_RESPONSE_MIDDLE):
 110                 qp->s_cur_sge = &qp->s_rdma_sge;
 111                 len = qp->s_rdma_len;
 112                 if (len > pmtu)
 113                         len = pmtu;
 114                 else {
 115                         ohdr->u.aeth = ipath_compute_aeth(qp);
 116                         hwords++;
 117                         qp->s_ack_state = OP(RDMA_READ_RESPONSE_LAST);
 118                 }
 119                 qp->s_rdma_len -= len;
 120                 bth0 = qp->s_ack_state << 24;
 121                 break;
 122
 123         case OP(RDMA_READ_RESPONSE_LAST):
 124         case OP(RDMA_READ_RESPONSE_ONLY):
 125                 /*
 126                  * We have to prevent new requests from changing
 127                  * the r_sge state while a ipath_verbs_send()
 128                  * is in progress.
 129                  */
 130                 qp->s_ack_state = OP(ACKNOWLEDGE);
 131                 bth0 = 0;
 132                 goto bail;
 133
 134         case OP(COMPARE_SWAP):
 135         case OP(FETCH_ADD):
 136                 qp->s_cur_sge = NULL;
 137                 len = 0;
 138                 /*
 139                  * Set the s_ack_state so the receive interrupt handler
 140                  * won't try to send an ACK (out of order) until this one
 141                  * is actually sent.
 142                  */
 143                 qp->s_ack_state = OP(RDMA_READ_RESPONSE_LAST);
 144                 bth0 = OP(ATOMIC_ACKNOWLEDGE) << 24;
 145                 ohdr->u.at.aeth = ipath_compute_aeth(qp);
 146                 ohdr->u.at.atomic_ack_eth = cpu_to_be64(qp->r_atomic_data);
 147                 hwords += sizeof(ohdr->u.at) / 4;
 148                 break;
 149
 150         default:
 151                 /* Send a regular ACK. */
 152                 qp->s_cur_sge = NULL;
 153                 len = 0;
 154                 /*
 155                  * Set the s_ack_state so the receive interrupt handler
 156                  * won't try to send an ACK (out of order) until this one
 157                  * is actually sent.
 158                  */
 159                 qp->s_ack_state = OP(RDMA_READ_RESPONSE_LAST);
 160                 bth0 = OP(ACKNOWLEDGE) << 24;
 161                 if (qp->s_nak_state)
 162                         ohdr->u.aeth = cpu_to_be32((qp->r_msn & IPATH_MSN_MASK) |
 163                                                     (qp->s_nak_state <<
 164                                                      IPATH_AETH_CREDIT_SHIFT));
 165                 else
 166                         ohdr->u.aeth = ipath_compute_aeth(qp);
 167                 hwords++;
 168         }
 169         qp->s_hdrwords = hwords;
 170         qp->s_cur_size = len;
 171
 172 bail:
 173         return bth0;
 174 }
 175
 176 /**
 177  * ipath_make_rc_req - construct a request packet (SEND, RDMA r/w, ATOMIC)
 178  * @qp: a pointer to the QP
 179  * @ohdr: a pointer to the IB header being constructed
 180  * @pmtu: the path MTU
 181  * @bth0p: pointer to the BTH opcode word
 182  * @bth2p: pointer to the BTH PSN word
 183  *
 184  * Return 1 if constructed; otherwise, return 0.
 185  * Note the QP s_lock must be held and interrupts disabled.
 186  */
 187 int ipath_make_rc_req(struct ipath_qp *qp,
 188                       struct ipath_other_headers *ohdr,
 189                       u32 pmtu, u32 *bth0p, u32 *bth2p)
 190 {
 191         struct ipath_ibdev *dev = to_idev(qp->ibqp.device);
 192         struct ipath_sge_state *ss;
 193         struct ipath_swqe *wqe;
 194         u32 hwords;
 195         u32 len;
 196         u32 bth0;
 197         u32 bth2;
 198         char newreq;
 199
 200         if (!(ib_ipath_state_ops[qp->state] & IPATH_PROCESS_SEND_OK) ||
 201             qp->s_rnr_timeout)
 202                 goto done;
 203
 204         /* Limit the number of packets sent without an ACK. */
 205         if (ipath_cmp24(qp->s_psn, qp->s_last_psn + IPATH_PSN_CREDIT) > 0) {
 206                 qp->s_wait_credit = 1;
 207                 dev->n_rc_stalls++;
 208                 spin_lock(&dev->pending_lock);
 209                 if (list_empty(&qp->timerwait))
 210                         list_add_tail(&qp->timerwait,
 211                                       &dev->pending[dev->pending_index]);
 212                 spin_unlock(&dev->pending_lock);
 213                 goto done;
 214         }
 215
 216         /* header size in 32-bit words LRH+BTH = (8+12)/4. */
 217         hwords = 5;
 218         bth0 = 0;
 219
 220         /* Send a request. */
 221         wqe = get_swqe_ptr(qp, qp->s_cur);
 222         switch (qp->s_state) {
 223         default:
 224                 /*
 225                  * Resend an old request or start a new one.
 226                  *
 227                  * We keep track of the current SWQE so that
 228                  * we don't reset the "furthest progress" state
 229                  * if we need to back up.
 230                  */
 231                 newreq = 0;
 232                 if (qp->s_cur == qp->s_tail) {
 233                         /* Check if send work queue is empty. */
 234                         if (qp->s_tail == qp->s_head)
 235                                 goto done;
 236                         wqe->psn = qp->s_next_psn;
 237                         newreq = 1;
 238                 }
 239                 /*
 240                  * Note that we have to be careful not to modify the
 241                  * original work request since we may need to resend
 242                  * it.
 243                  */
 244                 qp->s_sge.sge = wqe->sg_list[0];
 245                 qp->s_sge.sg_list = wqe->sg_list + 1;
 246                 qp->s_sge.num_sge = wqe->wr.num_sge;
 247                 qp->s_len = len = wqe->length;
 248                 ss = &qp->s_sge;
 249                 bth2 = 0;
 250                 switch (wqe->wr.opcode) {
 251                 case IB_WR_SEND:
 252                 case IB_WR_SEND_WITH_IMM:
 253                         /* If no credit, return. */
 254                         if (qp->s_lsn != (u32) -1 &&
 255                             ipath_cmp24(wqe->ssn, qp->s_lsn + 1) > 0)
 256                                 goto done;
 257                         wqe->lpsn = wqe->psn;
 258                         if (len > pmtu) {
 259                                 wqe->lpsn += (len - 1) / pmtu;
 260                                 qp->s_state = OP(SEND_FIRST);
 261                                 len = pmtu;
 262                                 break;
 263                         }
 264                         if (wqe->wr.opcode == IB_WR_SEND)
 265                                 qp->s_state = OP(SEND_ONLY);
 266                         else {
 267                                 qp->s_state = OP(SEND_ONLY_WITH_IMMEDIATE);
 268                                 /* Immediate data comes after the BTH */
 269                                 ohdr->u.imm_data = wqe->wr.imm_data;
 270                                 hwords += 1;
 271                         }
 272                         if (wqe->wr.send_flags & IB_SEND_SOLICITED)
 273                                 bth0 |= 1 << 23;
 274                         bth2 = 1 << 31; /* Request ACK. */
 275                         if (++qp->s_cur == qp->s_size)
 276                                 qp->s_cur = 0;
 277                         break;
 278
 279                 case IB_WR_RDMA_WRITE:
 280                         if (newreq && qp->s_lsn != (u32) -1)
 281                                 qp->s_lsn++;
 282                         /* FALLTHROUGH */
 283                 case IB_WR_RDMA_WRITE_WITH_IMM:
 284                         /* If no credit, return. */
 285                         if (qp->s_lsn != (u32) -1 &&
 286                             ipath_cmp24(wqe->ssn, qp->s_lsn + 1) > 0)
 287                                 goto done;
 288                         ohdr->u.rc.reth.vaddr =
 289                                 cpu_to_be64(wqe->wr.wr.rdma.remote_addr);
 290                         ohdr->u.rc.reth.rkey =
 291                                 cpu_to_be32(wqe->wr.wr.rdma.rkey);
 292                         ohdr->u.rc.reth.length = cpu_to_be32(len);
 293                         hwords += sizeof(struct ib_reth) / 4;
 294                         wqe->lpsn = wqe->psn;
 295                         if (len > pmtu) {
 296                                 wqe->lpsn += (len - 1) / pmtu;
 297                                 qp->s_state = OP(RDMA_WRITE_FIRST);
 298                                 len = pmtu;
 299                                 break;
 300                         }
 301                         if (wqe->wr.opcode == IB_WR_RDMA_WRITE)
 302                                 qp->s_state = OP(RDMA_WRITE_ONLY);
 303                         else {
 304                                 qp->s_state =
 305                                         OP(RDMA_WRITE_ONLY_WITH_IMMEDIATE);
 306                                 /* Immediate data comes after RETH */
 307                                 ohdr->u.rc.imm_data = wqe->wr.imm_data;
 308                                 hwords += 1;
 309                                 if (wqe->wr.send_flags & IB_SEND_SOLICITED)
 310                                         bth0 |= 1 << 23;
 311                         }
 312                         bth2 = 1 << 31; /* Request ACK. */
 313                         if (++qp->s_cur == qp->s_size)
 314                                 qp->s_cur = 0;
 315                         break;
 316
 317                 case IB_WR_RDMA_READ:
 318                         ohdr->u.rc.reth.vaddr =
 319                                 cpu_to_be64(wqe->wr.wr.rdma.remote_addr);
 320                         ohdr->u.rc.reth.rkey =
 321                                 cpu_to_be32(wqe->wr.wr.rdma.rkey);
 322                         ohdr->u.rc.reth.length = cpu_to_be32(len);
 323                         qp->s_state = OP(RDMA_READ_REQUEST);
 324                         hwords += sizeof(ohdr->u.rc.reth) / 4;
 325                         if (newreq) {
 326                                 if (qp->s_lsn != (u32) -1)
 327                                         qp->s_lsn++;
 328                                 /*
 329                                  * Adjust s_next_psn to count the
 330                                  * expected number of responses.
 331                                  */
 332                                 if (len > pmtu)
 333                                         qp->s_next_psn += (len - 1) / pmtu;
 334                                 wqe->lpsn = qp->s_next_psn++;
 335                         }
 336                         ss = NULL;
 337                         len = 0;
 338                         if (++qp->s_cur == qp->s_size)
 339                                 qp->s_cur = 0;
 340                         break;
 341
 342                 case IB_WR_ATOMIC_CMP_AND_SWP:
 343                 case IB_WR_ATOMIC_FETCH_AND_ADD:
 344                         if (wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP)
 345                                 qp->s_state = OP(COMPARE_SWAP);
 346                         else
 347                                 qp->s_state = OP(FETCH_ADD);
 348                         ohdr->u.atomic_eth.vaddr = cpu_to_be64(
 349                                 wqe->wr.wr.atomic.remote_addr);
 350                         ohdr->u.atomic_eth.rkey = cpu_to_be32(
 351                                 wqe->wr.wr.atomic.rkey);
 352                         ohdr->u.atomic_eth.swap_data = cpu_to_be64(
 353                                 wqe->wr.wr.atomic.swap);
 354                         ohdr->u.atomic_eth.compare_data = cpu_to_be64(
 355                                 wqe->wr.wr.atomic.compare_add);
 356                         hwords += sizeof(struct ib_atomic_eth) / 4;
 357                         if (newreq) {
 358                                 if (qp->s_lsn != (u32) -1)
 359                                         qp->s_lsn++;
 360                                 wqe->lpsn = wqe->psn;
 361                         }
 362                         if (++qp->s_cur == qp->s_size)
 363                                 qp->s_cur = 0;
 364                         ss = NULL;
 365                         len = 0;
 366                         break;
 367
 368                 default:
 369                         goto done;
 370                 }
 371                 if (newreq) {
 372                         qp->s_tail++;
 373                         if (qp->s_tail >= qp->s_size)
 374                                 qp->s_tail = 0;
 375                 }
 376                 bth2 |= qp->s_psn++ & IPATH_PSN_MASK;
 377                 if ((int)(qp->s_psn - qp->s_next_psn) > 0)
 378                         qp->s_next_psn = qp->s_psn;
 379                 /*
 380                  * Put the QP on the pending list so lost ACKs will cause
 381                  * a retry.  More than one request can be pending so the
 382                  * QP may already be on the dev->pending list.
 383                  */
 384                 spin_lock(&dev->pending_lock);
 385                 if (list_empty(&qp->timerwait))
 386                         list_add_tail(&qp->timerwait,
 387                                       &dev->pending[dev->pending_index]);
 388                 spin_unlock(&dev->pending_lock);
 389                 break;
 390
 391         case OP(RDMA_READ_RESPONSE_FIRST):
 392                 /*
 393                  * This case can only happen if a send is restarted.
 394                  * See ipath_restart_rc().
 395                  */
 396                 ipath_init_restart(qp, wqe);
 397                 /* FALLTHROUGH */
 398         case OP(SEND_FIRST):
 399                 qp->s_state = OP(SEND_MIDDLE);
 400                 /* FALLTHROUGH */
 401         case OP(SEND_MIDDLE):
 402                 bth2 = qp->s_psn++ & IPATH_PSN_MASK;
 403                 if ((int)(qp->s_psn - qp->s_next_psn) > 0)
 404                         qp->s_next_psn = qp->s_psn;
 405                 ss = &qp->s_sge;
 406                 len = qp->s_len;
 407                 if (len > pmtu) {
 408                         len = pmtu;
 409                         break;
 410                 }
 411                 if (wqe->wr.opcode == IB_WR_SEND)
 412                         qp->s_state = OP(SEND_LAST);
 413                 else {
 414                         qp->s_state = OP(SEND_LAST_WITH_IMMEDIATE);
 415                         /* Immediate data comes after the BTH */
 416                         ohdr->u.imm_data = wqe->wr.imm_data;
 417                         hwords += 1;
 418                 }
 419                 if (wqe->wr.send_flags & IB_SEND_SOLICITED)
 420                         bth0 |= 1 << 23;
 421                 bth2 |= 1 << 31;        /* Request ACK. */
 422                 qp->s_cur++;
 423                 if (qp->s_cur >= qp->s_size)
 424                         qp->s_cur = 0;
 425                 break;
 426
 427         case OP(RDMA_READ_RESPONSE_LAST):
 428                 /*
 429                  * This case can only happen if a RDMA write is restarted.
 430                  * See ipath_restart_rc().
 431                  */
 432                 ipath_init_restart(qp, wqe);
 433                 /* FALLTHROUGH */
 434         case OP(RDMA_WRITE_FIRST):
 435                 qp->s_state = OP(RDMA_WRITE_MIDDLE);
 436                 /* FALLTHROUGH */
 437         case OP(RDMA_WRITE_MIDDLE):
 438                 bth2 = qp->s_psn++ & IPATH_PSN_MASK;
 439                 if ((int)(qp->s_psn - qp->s_next_psn) > 0)
 440                         qp->s_next_psn = qp->s_psn;
 441                 ss = &qp->s_sge;
 442                 len = qp->s_len;
 443                 if (len > pmtu) {
 444                         len = pmtu;
 445                         break;
 446                 }
 447                 if (wqe->wr.opcode == IB_WR_RDMA_WRITE)
 448                         qp->s_state = OP(RDMA_WRITE_LAST);
 449                 else {
 450                         qp->s_state = OP(RDMA_WRITE_LAST_WITH_IMMEDIATE);
 451                         /* Immediate data comes after the BTH */
 452                         ohdr->u.imm_data = wqe->wr.imm_data;
 453                         hwords += 1;
 454                         if (wqe->wr.send_flags & IB_SEND_SOLICITED)
 455                                 bth0 |= 1 << 23;
 456                 }
 457                 bth2 |= 1 << 31;        /* Request ACK. */
 458                 qp->s_cur++;
 459                 if (qp->s_cur >= qp->s_size)
 460                         qp->s_cur = 0;
 461                 break;
 462
 463         case OP(RDMA_READ_RESPONSE_MIDDLE):
 464                 /*
 465                  * This case can only happen if a RDMA read is restarted.
 466                  * See ipath_restart_rc().
 467                  */
 468                 ipath_init_restart(qp, wqe);
 469                 len = ((qp->s_psn - wqe->psn) & IPATH_PSN_MASK) * pmtu;
 470                 ohdr->u.rc.reth.vaddr =
 471                         cpu_to_be64(wqe->wr.wr.rdma.remote_addr + len);
 472                 ohdr->u.rc.reth.rkey =
 473                         cpu_to_be32(wqe->wr.wr.rdma.rkey);
 474                 ohdr->u.rc.reth.length = cpu_to_be32(qp->s_len);
 475                 qp->s_state = OP(RDMA_READ_REQUEST);
 476                 hwords += sizeof(ohdr->u.rc.reth) / 4;
 477                 bth2 = qp->s_psn++ & IPATH_PSN_MASK;
 478                 if ((int)(qp->s_psn - qp->s_next_psn) > 0)
 479                         qp->s_next_psn = qp->s_psn;
 480                 ss = NULL;
 481                 len = 0;
 482                 qp->s_cur++;
 483                 if (qp->s_cur == qp->s_size)
 484                         qp->s_cur = 0;
 485                 break;
 486
 487         case OP(RDMA_READ_REQUEST):
 488         case OP(COMPARE_SWAP):
 489         case OP(FETCH_ADD):
 490                 /*
 491                  * We shouldn't start anything new until this request is
 492                  * finished.  The ACK will handle rescheduling us.  XXX The
 493                  * number of outstanding ones is negotiated at connection
 494                  * setup time (see pg. 258,289)?  XXX Also, if we support
 495                  * multiple outstanding requests, we need to check the WQE
 496                  * IB_SEND_FENCE flag and not send a new request if a RDMA
 497                  * read or atomic is pending.
 498                  */
 499                 goto done;
 500         }
 501         if (ipath_cmp24(qp->s_psn, qp->s_last_psn + IPATH_PSN_CREDIT - 1) >= 0)
 502                 bth2 |= 1 << 31;        /* Request ACK. */
 503         qp->s_len -= len;
 504         qp->s_hdrwords = hwords;
 505         qp->s_cur_sge = ss;
 506         qp->s_cur_size = len;
 507         *bth0p = bth0 | (qp->s_state << 24);
 508         *bth2p = bth2;
 509         return 1;
 510
 511 done:
 512         return 0;
 513 }
 514
 515 /**
 516  * send_rc_ack - Construct an ACK packet and send it
 517  * @qp: a pointer to the QP
 518  *
 519  * This is called from ipath_rc_rcv() and only uses the receive
 520  * side QP state.
 521  * Note that RDMA reads are handled in the send side QP state and tasklet.
 522  */
 523 static void send_rc_ack(struct ipath_qp *qp)
 524 {
 525         struct ipath_ibdev *dev = to_idev(qp->ibqp.device);
 526         u16 lrh0;
 527         u32 bth0;
 528         u32 hwords;
 529         struct ipath_ib_header hdr;
 530         struct ipath_other_headers *ohdr;
 531
 532         /* Construct the header. */
 533         ohdr = &hdr.u.oth;
 534         lrh0 = IPATH_LRH_BTH;
 535         /* header size in 32-bit words LRH+BTH+AETH = (8+12+4)/4. */
 536         hwords = 6;
 537         if (unlikely(qp->remote_ah_attr.ah_flags & IB_AH_GRH)) {
 538                 hwords += ipath_make_grh(dev, &hdr.u.l.grh,
 539                                          &qp->remote_ah_attr.grh,
 540                                          hwords, 0);
 541                 ohdr = &hdr.u.l.oth;
 542                 lrh0 = IPATH_LRH_GRH;
 543         }
 544         /* read pkey_index w/o lock (its atomic) */
 545         bth0 = ipath_get_pkey(dev->dd, qp->s_pkey_index);
 546         if (qp->r_nak_state)
 547                 ohdr->u.aeth = cpu_to_be32((qp->r_msn & IPATH_MSN_MASK) |
 548                                             (qp->r_nak_state <<
 549                                              IPATH_AETH_CREDIT_SHIFT));
 550         else
 551                 ohdr->u.aeth = ipath_compute_aeth(qp);
 552         if (qp->r_ack_state >= OP(COMPARE_SWAP)) {
 553                 bth0 |= OP(ATOMIC_ACKNOWLEDGE) << 24;
 554                 ohdr->u.at.atomic_ack_eth = cpu_to_be64(qp->r_atomic_data);
 555                 hwords += sizeof(ohdr->u.at.atomic_ack_eth) / 4;
 556         } else
 557                 bth0 |= OP(ACKNOWLEDGE) << 24;
 558         lrh0 |= qp->remote_ah_attr.sl << 4;
 559         hdr.lrh[0] = cpu_to_be16(lrh0);
 560         hdr.lrh[1] = cpu_to_be16(qp->remote_ah_attr.dlid);
 561         hdr.lrh[2] = cpu_to_be16(hwords + SIZE_OF_CRC);
 562         hdr.lrh[3] = cpu_to_be16(dev->dd->ipath_lid);
 563         ohdr->bth[0] = cpu_to_be32(bth0);
 564         ohdr->bth[1] = cpu_to_be32(qp->remote_qpn);
 565         ohdr->bth[2] = cpu_to_be32(qp->r_ack_psn & IPATH_PSN_MASK);
 566
 567         /*
 568          * If we can send the ACK, clear the ACK state.
 569          */
 570         if (ipath_verbs_send(dev->dd, hwords, (u32 *) &hdr, 0, NULL) == 0) {
 571                 qp->r_ack_state = OP(ACKNOWLEDGE);
 572                 dev->n_unicast_xmit++;
 573         } else {
 574                 /*
 575                  * We are out of PIO buffers at the moment.
 576                  * Pass responsibility for sending the ACK to the
 577                  * send tasklet so that when a PIO buffer becomes
 578                  * available, the ACK is sent ahead of other outgoing
 579                  * packets.
 580                  */
 581                 dev->n_rc_qacks++;
 582                 spin_lock_irq(&qp->s_lock);
 583                 /* Don't coalesce if a RDMA read or atomic is pending. */
 584                 if (qp->s_ack_state == OP(ACKNOWLEDGE) ||
 585                     qp->s_ack_state < OP(RDMA_READ_REQUEST)) {
 586                         qp->s_ack_state = qp->r_ack_state;
 587                         qp->s_nak_state = qp->r_nak_state;
 588                         qp->s_ack_psn = qp->r_ack_psn;
 589                         qp->r_ack_state = OP(ACKNOWLEDGE);
 590                 }
 591                 spin_unlock_irq(&qp->s_lock);
 592
 593                 /* Call ipath_do_rc_send() in another thread. */
 594                 tasklet_hi_schedule(&qp->s_task);
 595         }
 596 }
 597
 598 /**
 599  * reset_psn - reset the QP state to send starting from PSN
 600  * @qp: the QP
 601  * @psn: the packet sequence number to restart at
 602  *
 603  * This is called from ipath_rc_rcv() to process an incoming RC ACK
 604  * for the given QP.
 605  * Called at interrupt level with the QP s_lock held.
 606  */
 607 static void reset_psn(struct ipath_qp *qp, u32 psn)
 608 {
 609         u32 n = qp->s_last;
 610         struct ipath_swqe *wqe = get_swqe_ptr(qp, n);
 611         u32 opcode;
 612
 613         qp->s_cur = n;
 614
 615         /*
 616          * If we are starting the request from the beginning,
 617          * let the normal send code handle initialization.
 618          */
 619         if (ipath_cmp24(psn, wqe->psn) <= 0) {
 620                 qp->s_state = OP(SEND_LAST);
 621                 goto done;
 622         }
 623
 624         /* Find the work request opcode corresponding to the given PSN. */
 625         opcode = wqe->wr.opcode;
 626         for (;;) {
 627                 int diff;
 628
 629                 if (++n == qp->s_size)
 630                         n = 0;
 631                 if (n == qp->s_tail)
 632                         break;
 633                 wqe = get_swqe_ptr(qp, n);
 634                 diff = ipath_cmp24(psn, wqe->psn);
 635                 if (diff < 0)
 636                         break;
 637                 qp->s_cur = n;
 638                 /*
 639                  * If we are starting the request from the beginning,
 640                  * let the normal send code handle initialization.
 641                  */
 642                 if (diff == 0) {
 643                         qp->s_state = OP(SEND_LAST);
 644                         goto done;
 645                 }
 646                 opcode = wqe->wr.opcode;
 647         }
 648
 649         /*
 650          * Set the state to restart in the middle of a request.
 651          * Don't change the s_sge, s_cur_sge, or s_cur_size.
 652          * See ipath_do_rc_send().
 653          */
 654         switch (opcode) {
 655         case IB_WR_SEND:
 656         case IB_WR_SEND_WITH_IMM:
 657                 qp->s_state = OP(RDMA_READ_RESPONSE_FIRST);
 658                 break;
 659
 660         case IB_WR_RDMA_WRITE:
 661         case IB_WR_RDMA_WRITE_WITH_IMM:
 662                 qp->s_state = OP(RDMA_READ_RESPONSE_LAST);
 663                 break;
 664
 665         case IB_WR_RDMA_READ:
 666                 qp->s_state = OP(RDMA_READ_RESPONSE_MIDDLE);
 667                 break;
 668
 669         default:
 670                 /*
 671                  * This case shouldn't happen since its only
 672                  * one PSN per req.
 673                  */
 674                 qp->s_state = OP(SEND_LAST);
 675         }
 676 done:
 677         qp->s_psn = psn;
 678 }
 679
 680 /**
 681  * ipath_restart_rc - back up requester to resend the last un-ACKed request
 682  * @qp: the QP to restart
 683  * @psn: packet sequence number for the request
 684  * @wc: the work completion request
 685  *
 686  * The QP s_lock should be held and interrupts disabled.
 687  */
 688 void ipath_restart_rc(struct ipath_qp *qp, u32 psn, struct ib_wc *wc)
 689 {
 690         struct ipath_swqe *wqe = get_swqe_ptr(qp, qp->s_last);
 691         struct ipath_ibdev *dev;
 692
 693         /*
 694          * If there are no requests pending, we are done.
 695          */
 696         if (ipath_cmp24(psn, qp->s_next_psn) >= 0 ||
 697             qp->s_last == qp->s_tail)
 698                 goto done;
 699
 700         if (qp->s_retry == 0) {
 701                 wc->wr_id = wqe->wr.wr_id;
 702                 wc->status = IB_WC_RETRY_EXC_ERR;
 703                 wc->opcode = ib_ipath_wc_opcode[wqe->wr.opcode];
 704                 wc->vendor_err = 0;
 705                 wc->byte_len = 0;
 706                 wc->qp_num = qp->ibqp.qp_num;
 707                 wc->src_qp = qp->remote_qpn;
 708                 wc->pkey_index = 0;
 709                 wc->slid = qp->remote_ah_attr.dlid;
 710                 wc->sl = qp->remote_ah_attr.sl;
 711                 wc->dlid_path_bits = 0;
 712                 wc->port_num = 0;
 713                 ipath_sqerror_qp(qp, wc);
 714                 goto bail;
 715         }
 716         qp->s_retry--;
 717
 718         /*
 719          * Remove the QP from the timeout queue.
 720          * Note: it may already have been removed by ipath_ib_timer().
 721          */
 722         dev = to_idev(qp->ibqp.device);
 723         spin_lock(&dev->pending_lock);
 724         if (!list_empty(&qp->timerwait))
 725                 list_del_init(&qp->timerwait);
 726         spin_unlock(&dev->pending_lock);
 727
 728         if (wqe->wr.opcode == IB_WR_RDMA_READ)
 729                 dev->n_rc_resends++;
 730         else
 731                 dev->n_rc_resends += (int)qp->s_psn - (int)psn;
 732
 733         reset_psn(qp, psn);
 734
 735 done:
 736         tasklet_hi_schedule(&qp->s_task);
 737
 738 bail:
 739         return;
 740 }
 741
 742 static inline void update_last_psn(struct ipath_qp *qp, u32 psn)
 743 {
 744         if (qp->s_wait_credit) {
 745                 qp->s_wait_credit = 0;
 746                 tasklet_hi_schedule(&qp->s_task);
 747         }
 748         qp->s_last_psn = psn;
 749 }
 750
 751 /**
 752  * do_rc_ack - process an incoming RC ACK
 753  * @qp: the QP the ACK came in on
 754  * @psn: the packet sequence number of the ACK
 755  * @opcode: the opcode of the request that resulted in the ACK
 756  *
 757  * This is called from ipath_rc_rcv_resp() to process an incoming RC ACK
 758  * for the given QP.
 759  * Called at interrupt level with the QP s_lock held and interrupts disabled.
 760  * Returns 1 if OK, 0 if current operation should be aborted (NAK).
 761  */
 762 static int do_rc_ack(struct ipath_qp *qp, u32 aeth, u32 psn, int opcode)
 763 {
 764         struct ipath_ibdev *dev = to_idev(qp->ibqp.device);
 765         struct ib_wc wc;
 766         struct ipath_swqe *wqe;
 767         int ret = 0;
 768
 769         /*
 770          * Remove the QP from the timeout queue (or RNR timeout queue).
 771          * If ipath_ib_timer() has already removed it,
 772          * it's OK since we hold the QP s_lock and ipath_restart_rc()
 773          * just won't find anything to restart if we ACK everything.
 774          */
 775         spin_lock(&dev->pending_lock);
 776         if (!list_empty(&qp->timerwait))
 777                 list_del_init(&qp->timerwait);
 778         spin_unlock(&dev->pending_lock);
 779
 780         /*
 781          * Note that NAKs implicitly ACK outstanding SEND and RDMA write
 782          * requests and implicitly NAK RDMA read and atomic requests issued
 783          * before the NAK'ed request.  The MSN won't include the NAK'ed
 784          * request but will include an ACK'ed request(s).
 785          */
 786         wqe = get_swqe_ptr(qp, qp->s_last);
 787
 788         /* Nothing is pending to ACK/NAK. */
 789         if (qp->s_last == qp->s_tail)
 790                 goto bail;
 791
 792         /*
 793          * The MSN might be for a later WQE than the PSN indicates so
 794          * only complete WQEs that the PSN finishes.
 795          */
 796         while (ipath_cmp24(psn, wqe->lpsn) >= 0) {
 797                 /* If we are ACKing a WQE, the MSN should be >= the SSN. */
 798                 if (ipath_cmp24(aeth, wqe->ssn) < 0)
 799                         break;
 800                 /*
 801                  * If this request is a RDMA read or atomic, and the ACK is
 802                  * for a later operation, this ACK NAKs the RDMA read or
 803                  * atomic.  In other words, only a RDMA_READ_LAST or ONLY
 804                  * can ACK a RDMA read and likewise for atomic ops.  Note
 805                  * that the NAK case can only happen if relaxed ordering is
 806                  * used and requests are sent after an RDMA read or atomic
 807                  * is sent but before the response is received.
 808                  */
 809                 if ((wqe->wr.opcode == IB_WR_RDMA_READ &&
 810                      opcode != OP(RDMA_READ_RESPONSE_LAST)) ||
 811                     ((wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP ||
 812                       wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD) &&
 813                      (opcode != OP(ATOMIC_ACKNOWLEDGE) ||
 814                       ipath_cmp24(wqe->psn, psn) != 0))) {
 815                         /*
 816                          * The last valid PSN seen is the previous
 817                          * request's.
 818                          */
 819                         update_last_psn(qp, wqe->psn - 1);
 820                         /* Retry this request. */
 821                         ipath_restart_rc(qp, wqe->psn, &wc);
 822                         /*
 823                          * No need to process the ACK/NAK since we are
 824                          * restarting an earlier request.
 825                          */
 826                         goto bail;
 827                 }
 828                 /* Post a send completion queue entry if requested. */
 829                 if (!test_bit(IPATH_S_SIGNAL_REQ_WR, &qp->s_flags) ||
 830                     (wqe->wr.send_flags & IB_SEND_SIGNALED)) {
 831                         wc.wr_id = wqe->wr.wr_id;
 832                         wc.status = IB_WC_SUCCESS;
 833                         wc.opcode = ib_ipath_wc_opcode[wqe->wr.opcode];
 834                         wc.vendor_err = 0;
 835                         wc.byte_len = wqe->length;
 836                         wc.qp_num = qp->ibqp.qp_num;
 837                         wc.src_qp = qp->remote_qpn;
 838                         wc.pkey_index = 0;
 839                         wc.slid = qp->remote_ah_attr.dlid;
 840                         wc.sl = qp->remote_ah_attr.sl;
 841                         wc.dlid_path_bits = 0;
 842                         wc.port_num = 0;
 843                         ipath_cq_enter(to_icq(qp->ibqp.send_cq), &wc, 0);
 844                 }
 845                 qp->s_retry = qp->s_retry_cnt;
 846                 /*
 847                  * If we are completing a request which is in the process of
 848                  * being resent, we can stop resending it since we know the
 849                  * responder has already seen it.
 850                  */
 851                 if (qp->s_last == qp->s_cur) {
 852                         if (++qp->s_cur >= qp->s_size)
 853                                 qp->s_cur = 0;
 854                         wqe = get_swqe_ptr(qp, qp->s_cur);
 855                         qp->s_state = OP(SEND_LAST);
 856                         qp->s_psn = wqe->psn;
 857                 }
 858                 if (++qp->s_last >= qp->s_size)
 859                         qp->s_last = 0;
 860                 wqe = get_swqe_ptr(qp, qp->s_last);
 861                 if (qp->s_last == qp->s_tail)
 862                         break;
 863         }
 864
 865         switch (aeth >> 29) {
 866         case 0:         /* ACK */
 867                 dev->n_rc_acks++;
 868                 /* If this is a partial ACK, reset the retransmit timer. */
 869                 if (qp->s_last != qp->s_tail) {
 870                         spin_lock(&dev->pending_lock);
 871                         list_add_tail(&qp->timerwait,
 872                                       &dev->pending[dev->pending_index]);
 873                         spin_unlock(&dev->pending_lock);
 874                 }
 875                 ipath_get_credit(qp, aeth);
 876                 qp->s_rnr_retry = qp->s_rnr_retry_cnt;
 877                 qp->s_retry = qp->s_retry_cnt;
 878                 update_last_psn(qp, psn);
 879                 ret = 1;
 880                 goto bail;
 881
 882         case 1:         /* RNR NAK */
 883                 dev->n_rnr_naks++;
 884                 if (qp->s_rnr_retry == 0) {
 885                         if (qp->s_last == qp->s_tail)
 886                                 goto bail;
 887
 888                         wc.status = IB_WC_RNR_RETRY_EXC_ERR;
 889                         goto class_b;
 890                 }
 891                 if (qp->s_rnr_retry_cnt < 7)
 892                         qp->s_rnr_retry--;
 893                 if (qp->s_last == qp->s_tail)
 894                         goto bail;
 895
 896                 /* The last valid PSN is the previous PSN. */
 897                 update_last_psn(qp, psn - 1);
 898
 899                 dev->n_rc_resends += (int)qp->s_psn - (int)psn;
 900
 901                 reset_psn(qp, psn);
 902
 903                 qp->s_rnr_timeout =
 904                         ib_ipath_rnr_table[(aeth >> IPATH_AETH_CREDIT_SHIFT) &
 905                                            IPATH_AETH_CREDIT_MASK];
 906                 ipath_insert_rnr_queue(qp);
 907                 goto bail;
 908
 909         case 3:         /* NAK */
 910                 /* The last valid PSN seen is the previous request's. */
 911                 if (qp->s_last != qp->s_tail)
 912                         update_last_psn(qp, wqe->psn - 1);
 913                 switch ((aeth >> IPATH_AETH_CREDIT_SHIFT) &
 914                         IPATH_AETH_CREDIT_MASK) {
 915                 case 0: /* PSN sequence error */
 916                         dev->n_seq_naks++;
 917                         /*
 918                          * Back up to the responder's expected PSN.  XXX
 919                          * Note that we might get a NAK in the middle of an
 920                          * RDMA READ response which terminates the RDMA
 921                          * READ.
 922                          */
 923                         if (qp->s_last == qp->s_tail)
 924                                 break;
 925
 926                         if (ipath_cmp24(psn, wqe->psn) < 0)
 927                                 break;
 928
 929                         /* Retry the request. */
 930                         ipath_restart_rc(qp, psn, &wc);
 931                         break;
 932
 933                 case 1: /* Invalid Request */
 934                         wc.status = IB_WC_REM_INV_REQ_ERR;
 935                         dev->n_other_naks++;
 936                         goto class_b;
 937
 938                 case 2: /* Remote Access Error */
 939                         wc.status = IB_WC_REM_ACCESS_ERR;
 940                         dev->n_other_naks++;
 941                         goto class_b;
 942
 943                 case 3: /* Remote Operation Error */
 944                         wc.status = IB_WC_REM_OP_ERR;
 945                         dev->n_other_naks++;
 946                 class_b:
 947                         wc.wr_id = wqe->wr.wr_id;
 948                         wc.opcode = ib_ipath_wc_opcode[wqe->wr.opcode];
 949                         wc.vendor_err = 0;
 950                         wc.byte_len = 0;
 951                         wc.qp_num = qp->ibqp.qp_num;
 952                         wc.src_qp = qp->remote_qpn;
 953                         wc.pkey_index = 0;
 954                         wc.slid = qp->remote_ah_attr.dlid;
 955                         wc.sl = qp->remote_ah_attr.sl;
 956                         wc.dlid_path_bits = 0;
 957                         wc.port_num = 0;
 958                         ipath_sqerror_qp(qp, &wc);
 959                         break;
 960
 961                 default:
 962                         /* Ignore other reserved NAK error codes */
 963                         goto reserved;
 964                 }
 965                 qp->s_rnr_retry = qp->s_rnr_retry_cnt;
 966                 goto bail;
 967
 968         default:                /* 2: reserved */
 969         reserved:
 970                 /* Ignore reserved NAK codes. */
 971                 goto bail;
 972         }
 973
 974 bail:
 975         return ret;
 976 }
 977
 978 /**
 979  * ipath_rc_rcv_resp - process an incoming RC response packet
 980  * @dev: the device this packet came in on
 981  * @ohdr: the other headers for this packet
 982  * @data: the packet data
 983  * @tlen: the packet length
 984  * @qp: the QP for this packet
 985  * @opcode: the opcode for this packet
 986  * @psn: the packet sequence number for this packet
 987  * @hdrsize: the header length
 988  * @pmtu: the path MTU
 989  * @header_in_data: true if part of the header data is in the data buffer
 990  *
 991  * This is called from ipath_rc_rcv() to process an incoming RC response
 992  * packet for the given QP.
 993  * Called at interrupt level.
 994  */
 995 static inline void ipath_rc_rcv_resp(struct ipath_ibdev *dev,
 996                                      struct ipath_other_headers *ohdr,
 997                                      void *data, u32 tlen,
 998                                      struct ipath_qp *qp,
 999                                      u32 opcode,
1000                                      u32 psn, u32 hdrsize, u32 pmtu,
1001                                      int header_in_data)
1002 {
1003         unsigned long flags;
1004         struct ib_wc wc;
1005         int diff;
1006         u32 pad;
1007         u32 aeth;
1008
1009         spin_lock_irqsave(&qp->s_lock, flags);
1010
1011         /* Ignore invalid responses. */
1012         if (ipath_cmp24(psn, qp->s_next_psn) >= 0)
1013                 goto ack_done;
1014
1015         /* Ignore duplicate responses. */
1016         diff = ipath_cmp24(psn, qp->s_last_psn);
1017         if (unlikely(diff <= 0)) {
1018                 /* Update credits for "ghost" ACKs */
1019                 if (diff == 0 && opcode == OP(ACKNOWLEDGE)) {
1020                         if (!header_in_data)
1021                                 aeth = be32_to_cpu(ohdr->u.aeth);
1022                         else {
1023                                 aeth = be32_to_cpu(((__be32 *) data)[0]);
1024                                 data += sizeof(__be32);
1025                         }
1026                         if ((aeth >> 29) == 0)
1027                                 ipath_get_credit(qp, aeth);
1028                 }
1029                 goto ack_done;
1030         }
1031
1032         switch (opcode) {
1033         case OP(ACKNOWLEDGE):
1034         case OP(ATOMIC_ACKNOWLEDGE):
1035         case OP(RDMA_READ_RESPONSE_FIRST):
1036                 if (!header_in_data)
1037                         aeth = be32_to_cpu(ohdr->u.aeth);
1038                 else {
1039                         aeth = be32_to_cpu(((__be32 *) data)[0]);
1040                         data += sizeof(__be32);
1041                 }
1042                 if (opcode == OP(ATOMIC_ACKNOWLEDGE))
1043                         *(u64 *) qp->s_sge.sge.vaddr = *(u64 *) data;
1044                 if (!do_rc_ack(qp, aeth, psn, opcode) ||
1045                     opcode != OP(RDMA_READ_RESPONSE_FIRST))
1046                         goto ack_done;
1047                 hdrsize += 4;
1048                 /*
1049                  * do_rc_ack() has already checked the PSN so skip
1050                  * the sequence check.
1051                  */
1052                 goto rdma_read;
1053
1054         case OP(RDMA_READ_RESPONSE_MIDDLE):
1055                 /* no AETH, no ACK */
1056                 if (unlikely(ipath_cmp24(psn, qp->s_last_psn + 1))) {
1057                         dev->n_rdma_seq++;
1058                         ipath_restart_rc(qp, qp->s_last_psn + 1, &wc);
1059                         goto ack_done;
1060                 }
1061         rdma_read:
1062                 if (unlikely(qp->s_state != OP(RDMA_READ_REQUEST)))
1063                         goto ack_done;
1064                 if (unlikely(tlen != (hdrsize + pmtu + 4)))
1065                         goto ack_done;
1066                 if (unlikely(pmtu >= qp->s_len))
1067                         goto ack_done;
1068                 /* We got a response so update the timeout. */
1069                 if (unlikely(qp->s_last == qp->s_tail ||
1070                              get_swqe_ptr(qp, qp->s_last)->wr.opcode !=
1071                              IB_WR_RDMA_READ))
1072                         goto ack_done;
1073                 spin_lock(&dev->pending_lock);
1074                 if (qp->s_rnr_timeout == 0 && !list_empty(&qp->timerwait))
1075                         list_move_tail(&qp->timerwait,
1076                                        &dev->pending[dev->pending_index]);
1077                 spin_unlock(&dev->pending_lock);
1078                 /*
1079                  * Update the RDMA receive state but do the copy w/o
1080                  * holding the locks and blocking interrupts.
1081                  * XXX Yet another place that affects relaxed RDMA order
1082                  * since we don't want s_sge modified.
1083                  */
1084                 qp->s_len -= pmtu;
1085                 update_last_psn(qp, psn);
1086                 spin_unlock_irqrestore(&qp->s_lock, flags);
1087                 ipath_copy_sge(&qp->s_sge, data, pmtu);
1088                 goto bail;
1089
1090         case OP(RDMA_READ_RESPONSE_LAST):
1091                 /* ACKs READ req. */
1092                 if (unlikely(ipath_cmp24(psn, qp->s_last_psn + 1))) {
1093                         dev->n_rdma_seq++;
1094                         ipath_restart_rc(qp, qp->s_last_psn + 1, &wc);
1095                         goto ack_done;
1096                 }
1097                 /* FALLTHROUGH */
1098         case OP(RDMA_READ_RESPONSE_ONLY):
1099                 if (unlikely(qp->s_state != OP(RDMA_READ_REQUEST)))
1100                         goto ack_done;
1101                 /*
1102                  * Get the number of bytes the message was padded by.
1103                  */
1104                 pad = (be32_to_cpu(ohdr->bth[0]) >> 20) & 3;
1105                 /*
1106                  * Check that the data size is >= 1 && <= pmtu.
1107                  * Remember to account for the AETH header (4) and
1108                  * ICRC (4).
1109                  */
1110                 if (unlikely(tlen <= (hdrsize + pad + 8))) {
1111                         /* XXX Need to generate an error CQ entry. */
1112                         goto ack_done;
1113                 }
1114                 tlen -= hdrsize + pad + 8;
1115                 if (unlikely(tlen != qp->s_len)) {
1116                         /* XXX Need to generate an error CQ entry. */
1117                         goto ack_done;
1118                 }
1119                 if (!header_in_data)
1120                         aeth = be32_to_cpu(ohdr->u.aeth);
1121                 else {
1122                         aeth = be32_to_cpu(((__be32 *) data)[0]);
1123                         data += sizeof(__be32);
1124                 }
1125                 ipath_copy_sge(&qp->s_sge, data, tlen);
1126                 if (do_rc_ack(qp, aeth, psn, OP(RDMA_READ_RESPONSE_LAST))) {
1127                         /*
1128                          * Change the state so we contimue
1129                          * processing new requests and wake up the
1130                          * tasklet if there are posted sends.
1131                          */
1132                         qp->s_state = OP(SEND_LAST);
1133                         if (qp->s_tail != qp->s_head)
1134                                 tasklet_hi_schedule(&qp->s_task);
1135                 }
1136                 goto ack_done;
1137         }
1138
1139 ack_done:
1140         spin_unlock_irqrestore(&qp->s_lock, flags);
1141 bail:
1142         return;
1143 }
1144
1145 /**
1146  * ipath_rc_rcv_error - process an incoming duplicate or error RC packet
1147  * @dev: the device this packet came in on
1148  * @ohdr: the other headers for this packet
1149  * @data: the packet data
1150  * @qp: the QP for this packet
1151  * @opcode: the opcode for this packet
1152  * @psn: the packet sequence number for this packet
1153  * @diff: the difference between the PSN and the expected PSN
1154  * @header_in_data: true if part of the header data is in the data buffer
1155  *
1156  * This is called from ipath_rc_rcv() to process an unexpected
1157  * incoming RC packet for the given QP.
1158  * Called at interrupt level.
1159  * Return 1 if no more processing is needed; otherwise return 0 to
1160  * schedule a response to be sent and the s_lock unlocked.
1161  */
1162 static inline int ipath_rc_rcv_error(struct ipath_ibdev *dev,
1163                                      struct ipath_other_headers *ohdr,
1164                                      void *data,
1165                                      struct ipath_qp *qp,
1166                                      u32 opcode,
1167                                      u32 psn,
1168                                      int diff,
1169                                      int header_in_data)
1170 {
1171         struct ib_reth *reth;
1172
1173         if (diff > 0) {
1174                 /*
1175                  * Packet sequence error.
1176                  * A NAK will ACK earlier sends and RDMA writes.
1177                  * Don't queue the NAK if a RDMA read, atomic, or
1178                  * NAK is pending though.
1179                  */
1180                 if (qp->s_ack_state != OP(ACKNOWLEDGE) ||
1181                     qp->r_nak_state != 0)
1182                         goto done;
1183                 if (qp->r_ack_state < OP(COMPARE_SWAP)) {
1184                         qp->r_ack_state = OP(SEND_ONLY);
1185                         qp->r_nak_state = IB_NAK_PSN_ERROR;
1186                         /* Use the expected PSN. */
1187                         qp->r_ack_psn = qp->r_psn;
1188                 }
1189                 goto send_ack;
1190         }
1191
1192         /*
1193          * Handle a duplicate request.  Don't re-execute SEND, RDMA
1194          * write or atomic op.  Don't NAK errors, just silently drop
1195          * the duplicate request.  Note that r_sge, r_len, and
1196          * r_rcv_len may be in use so don't modify them.
1197          *
1198          * We are supposed to ACK the earliest duplicate PSN but we
1199          * can coalesce an outstanding duplicate ACK.  We have to
1200          * send the earliest so that RDMA reads can be restarted at
1201          * the requester's expected PSN.
1202          */
1203         if (opcode == OP(RDMA_READ_REQUEST)) {
1204                 /* RETH comes after BTH */
1205                 if (!header_in_data)
1206                         reth = &ohdr->u.rc.reth;
1207                 else {
1208                         reth = (struct ib_reth *)data;
1209                         data += sizeof(*reth);
1210                 }
1211                 /*
1212                  * If we receive a duplicate RDMA request, it means the
1213                  * requester saw a sequence error and needs to restart
1214                  * from an earlier point.  We can abort the current
1215                  * RDMA read send in that case.
1216                  */
1217                 spin_lock_irq(&qp->s_lock);
1218                 if (qp->s_ack_state != OP(ACKNOWLEDGE) &&
1219                     (qp->s_hdrwords || ipath_cmp24(psn, qp->s_ack_psn) >= 0)) {
1220                         /*
1221                          * We are already sending earlier requested data.
1222                          * Don't abort it to send later out of sequence data.
1223                          */
1224                         spin_unlock_irq(&qp->s_lock);
1225                         goto done;
1226                 }
1227                 qp->s_rdma_len = be32_to_cpu(reth->length);
1228                 if (qp->s_rdma_len != 0) {
1229                         u32 rkey = be32_to_cpu(reth->rkey);
1230                         u64 vaddr = be64_to_cpu(reth->vaddr);
1231                         int ok;
1232
1233                         /*
1234                          * Address range must be a subset of the original
1235                          * request and start on pmtu boundaries.
1236                          */
1237                         ok = ipath_rkey_ok(qp, &qp->s_rdma_sge,
1238                                            qp->s_rdma_len, vaddr, rkey,
1239                                            IB_ACCESS_REMOTE_READ);
1240                         if (unlikely(!ok)) {
1241                                 spin_unlock_irq(&qp->s_lock);
1242                                 goto done;
1243                         }
1244                 } else {
1245                         qp->s_rdma_sge.sg_list = NULL;
1246                         qp->s_rdma_sge.num_sge = 0;
1247                         qp->s_rdma_sge.sge.mr = NULL;
1248                         qp->s_rdma_sge.sge.vaddr = NULL;
1249                         qp->s_rdma_sge.sge.length = 0;
1250                         qp->s_rdma_sge.sge.sge_length = 0;
1251                 }
1252                 qp->s_ack_state = opcode;
1253                 qp->s_ack_psn = psn;
1254                 spin_unlock_irq(&qp->s_lock);
1255                 tasklet_hi_schedule(&qp->s_task);
1256                 goto send_ack;
1257         }
1258
1259         /*
1260          * A pending RDMA read will ACK anything before it so
1261          * ignore earlier duplicate requests.
1262          */
1263         if (qp->s_ack_state != OP(ACKNOWLEDGE))
1264                 goto done;
1265
1266         /*
1267          * If an ACK is pending, don't replace the pending ACK
1268          * with an earlier one since the later one will ACK the earlier.
1269          * Also, if we already have a pending atomic, send it.
1270          */
1271         if (qp->r_ack_state != OP(ACKNOWLEDGE) &&
1272             (ipath_cmp24(psn, qp->r_ack_psn) <= 0 ||
1273              qp->r_ack_state >= OP(COMPARE_SWAP)))
1274                 goto send_ack;
1275         switch (opcode) {
1276         case OP(COMPARE_SWAP):
1277         case OP(FETCH_ADD):
1278                 /*
1279                  * Check for the PSN of the last atomic operation
1280                  * performed and resend the result if found.
1281                  */
1282                 if ((psn & IPATH_PSN_MASK) != qp->r_atomic_psn)
1283                         goto done;
1284                 break;
1285         }
1286         qp->r_ack_state = opcode;
1287         qp->r_nak_state = 0;
1288         qp->r_ack_psn = psn;
1289 send_ack:
1290         return 0;
1291
1292 done:
1293         return 1;
1294 }
1295
1296 static void ipath_rc_error(struct ipath_qp *qp, enum ib_wc_status err)
1297 {
1298         spin_lock_irq(&qp->s_lock);
1299         qp->state = IB_QPS_ERR;
1300         ipath_error_qp(qp, err);
1301         spin_unlock_irq(&qp->s_lock);
1302 }
1303
1304 /**
1305  * ipath_rc_rcv - process an incoming RC packet
1306  * @dev: the device this packet came in on
1307  * @hdr: the header of this packet
1308  * @has_grh: true if the header has a GRH
1309  * @data: the packet data
1310  * @tlen: the packet length
1311  * @qp: the QP for this packet
1312  *
1313  * This is called from ipath_qp_rcv() to process an incoming RC packet
1314  * for the given QP.
1315  * Called at interrupt level.
1316  */
1317 void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
1318                   int has_grh, void *data, u32 tlen, struct ipath_qp *qp)
1319 {
1320         struct ipath_other_headers *ohdr;
1321         u32 opcode;
1322         u32 hdrsize;
1323         u32 psn;
1324         u32 pad;
1325         struct ib_wc wc;
1326         u32 pmtu = ib_mtu_enum_to_int(qp->path_mtu);
1327         int diff;
1328         struct ib_reth *reth;
1329         int header_in_data;
1330
1331         /* Validate the SLID. See Ch. 9.6.1.5 */
1332         if (unlikely(be16_to_cpu(hdr->lrh[3]) != qp->remote_ah_attr.dlid))
1333                 goto done;
1334
1335         /* Check for GRH */
1336         if (!has_grh) {
1337                 ohdr = &hdr->u.oth;
1338                 hdrsize = 8 + 12;       /* LRH + BTH */
1339                 psn = be32_to_cpu(ohdr->bth[2]);
1340                 header_in_data = 0;
1341         } else {
1342                 ohdr = &hdr->u.l.oth;
1343                 hdrsize = 8 + 40 + 12;  /* LRH + GRH + BTH */
1344                 /*
1345                  * The header with GRH is 60 bytes and the core driver sets
1346                  * the eager header buffer size to 56 bytes so the last 4
1347                  * bytes of the BTH header (PSN) is in the data buffer.
1348                  */
1349                 header_in_data = dev->dd->ipath_rcvhdrentsize == 16;
1350                 if (header_in_data) {
1351                         psn = be32_to_cpu(((__be32 *) data)[0]);
1352                         data += sizeof(__be32);
1353                 } else
1354                         psn = be32_to_cpu(ohdr->bth[2]);
1355         }
1356
1357         /*
1358          * Process responses (ACKs) before anything else.  Note that the
1359          * packet sequence number will be for something in the send work
1360          * queue rather than the expected receive packet sequence number.
1361          * In other words, this QP is the requester.
1362          */
1363         opcode = be32_to_cpu(ohdr->bth[0]) >> 24;
1364         if (opcode >= OP(RDMA_READ_RESPONSE_FIRST) &&
1365             opcode <= OP(ATOMIC_ACKNOWLEDGE)) {
1366                 ipath_rc_rcv_resp(dev, ohdr, data, tlen, qp, opcode, psn,
1367                                   hdrsize, pmtu, header_in_data);
1368                 goto done;
1369         }
1370
1371         /* Compute 24 bits worth of difference. */
1372         diff = ipath_cmp24(psn, qp->r_psn);
1373         if (unlikely(diff)) {
1374                 if (ipath_rc_rcv_error(dev, ohdr, data, qp, opcode,
1375                                        psn, diff, header_in_data))
1376                         goto done;
1377                 goto send_ack;
1378         }
1379
1380         /* Check for opcode sequence errors. */
1381         switch (qp->r_state) {
1382         case OP(SEND_FIRST):
1383         case OP(SEND_MIDDLE):
1384                 if (opcode == OP(SEND_MIDDLE) ||
1385                     opcode == OP(SEND_LAST) ||
1386                     opcode == OP(SEND_LAST_WITH_IMMEDIATE))
1387                         break;
1388         nack_inv:
1389                 /*
1390                  * A NAK will ACK earlier sends and RDMA writes.
1391                  * Don't queue the NAK if a RDMA read, atomic, or NAK
1392                  * is pending though.
1393                  */
1394                 if (qp->r_ack_state >= OP(COMPARE_SWAP))
1395                         goto send_ack;
1396                 ipath_rc_error(qp, IB_WC_REM_INV_REQ_ERR);
1397                 qp->r_ack_state = OP(SEND_ONLY);
1398                 qp->r_nak_state = IB_NAK_INVALID_REQUEST;
1399                 qp->r_ack_psn = qp->r_psn;
1400                 goto send_ack;
1401
1402         case OP(RDMA_WRITE_FIRST):
1403         case OP(RDMA_WRITE_MIDDLE):
1404                 if (opcode == OP(RDMA_WRITE_MIDDLE) ||
1405                     opcode == OP(RDMA_WRITE_LAST) ||
1406                     opcode == OP(RDMA_WRITE_LAST_WITH_IMMEDIATE))
1407                         break;
1408                 goto nack_inv;
1409
1410         default:
1411                 if (opcode == OP(SEND_MIDDLE) ||
1412                     opcode == OP(SEND_LAST) ||
1413                     opcode == OP(SEND_LAST_WITH_IMMEDIATE) ||
1414                     opcode == OP(RDMA_WRITE_MIDDLE) ||
1415                     opcode == OP(RDMA_WRITE_LAST) ||
1416                     opcode == OP(RDMA_WRITE_LAST_WITH_IMMEDIATE))
1417                         goto nack_inv;
1418                 /*
1419                  * Note that it is up to the requester to not send a new
1420                  * RDMA read or atomic operation before receiving an ACK
1421                  * for the previous operation.
1422                  */
1423                 break;
1424         }
1425
1426         wc.imm_data = 0;
1427         wc.wc_flags = 0;
1428
1429         /* OK, process the packet. */
1430         switch (opcode) {
1431         case OP(SEND_FIRST):
1432                 if (!ipath_get_rwqe(qp, 0)) {
1433                 rnr_nak:
1434                         /*
1435                          * A RNR NAK will ACK earlier sends and RDMA writes.
1436                          * Don't queue the NAK if a RDMA read or atomic
1437                          * is pending though.
1438                          */
1439                         if (qp->r_ack_state >= OP(COMPARE_SWAP))
1440                                 goto send_ack;
1441                         qp->r_ack_state = OP(SEND_ONLY);
1442                         qp->r_nak_state = IB_RNR_NAK | qp->r_min_rnr_timer;
1443                         qp->r_ack_psn = qp->r_psn;
1444                         goto send_ack;
1445                 }
1446                 qp->r_rcv_len = 0;
1447                 /* FALLTHROUGH */
1448         case OP(SEND_MIDDLE):
1449         case OP(RDMA_WRITE_MIDDLE):
1450         send_middle:
1451                 /* Check for invalid length PMTU or posted rwqe len. */
1452                 if (unlikely(tlen != (hdrsize + pmtu + 4)))
1453                         goto nack_inv;
1454                 qp->r_rcv_len += pmtu;
1455                 if (unlikely(qp->r_rcv_len > qp->r_len))
1456                         goto nack_inv;
1457                 ipath_copy_sge(&qp->r_sge, data, pmtu);
1458                 break;
1459
1460         case OP(RDMA_WRITE_LAST_WITH_IMMEDIATE):
1461                 /* consume RWQE */
1462                 if (!ipath_get_rwqe(qp, 1))
1463                         goto rnr_nak;
1464                 goto send_last_imm;
1465
1466         case OP(SEND_ONLY):
1467         case OP(SEND_ONLY_WITH_IMMEDIATE):
1468                 if (!ipath_get_rwqe(qp, 0))
1469                         goto rnr_nak;
1470                 qp->r_rcv_len = 0;
1471                 if (opcode == OP(SEND_ONLY))
1472                         goto send_last;
1473                 /* FALLTHROUGH */
1474         case OP(SEND_LAST_WITH_IMMEDIATE):
1475         send_last_imm:
1476                 if (header_in_data) {
1477                         wc.imm_data = *(__be32 *) data;
1478                         data += sizeof(__be32);
1479                 } else {
1480                         /* Immediate data comes after BTH */
1481                         wc.imm_data = ohdr->u.imm_data;
1482                 }
1483                 hdrsize += 4;
1484                 wc.wc_flags = IB_WC_WITH_IMM;
1485                 /* FALLTHROUGH */
1486         case OP(SEND_LAST):
1487         case OP(RDMA_WRITE_LAST):
1488         send_last:
1489                 /* Get the number of bytes the message was padded by. */
1490                 pad = (be32_to_cpu(ohdr->bth[0]) >> 20) & 3;
1491                 /* Check for invalid length. */
1492                 /* XXX LAST len should be >= 1 */
1493                 if (unlikely(tlen < (hdrsize + pad + 4)))
1494                         goto nack_inv;
1495                 /* Don't count the CRC. */
1496                 tlen -= (hdrsize + pad + 4);
1497                 wc.byte_len = tlen + qp->r_rcv_len;
1498                 if (unlikely(wc.byte_len > qp->r_len))
1499                         goto nack_inv;
1500                 ipath_copy_sge(&qp->r_sge, data, tlen);
1501                 qp->r_msn++;
1502                 if (!qp->r_wrid_valid)
1503                         break;
1504                 qp->r_wrid_valid = 0;
1505                 wc.wr_id = qp->r_wr_id;
1506                 wc.status = IB_WC_SUCCESS;
1507                 wc.opcode = IB_WC_RECV;
1508                 wc.vendor_err = 0;
1509                 wc.qp_num = qp->ibqp.qp_num;
1510                 wc.src_qp = qp->remote_qpn;
1511                 wc.pkey_index = 0;
1512                 wc.slid = qp->remote_ah_attr.dlid;
1513                 wc.sl = qp->remote_ah_attr.sl;
1514                 wc.dlid_path_bits = 0;
1515                 wc.port_num = 0;
1516                 /* Signal completion event if the solicited bit is set. */
1517                 ipath_cq_enter(to_icq(qp->ibqp.recv_cq), &wc,
1518                                (ohdr->bth[0] &
1519                                 __constant_cpu_to_be32(1 << 23)) != 0);
1520                 break;
1521
1522         case OP(RDMA_WRITE_FIRST):
1523         case OP(RDMA_WRITE_ONLY):
1524         case OP(RDMA_WRITE_ONLY_WITH_IMMEDIATE):
1525                 /* consume RWQE */
1526                 /* RETH comes after BTH */
1527                 if (!header_in_data)
1528                         reth = &ohdr->u.rc.reth;
1529                 else {
1530                         reth = (struct ib_reth *)data;
1531                         data += sizeof(*reth);
1532                 }
1533                 hdrsize += sizeof(*reth);
1534                 qp->r_len = be32_to_cpu(reth->length);
1535                 qp->r_rcv_len = 0;
1536                 if (qp->r_len != 0) {
1537                         u32 rkey = be32_to_cpu(reth->rkey);
1538                         u64 vaddr = be64_to_cpu(reth->vaddr);
1539                         int ok;
1540
1541                         /* Check rkey & NAK */
1542                         ok = ipath_rkey_ok(qp, &qp->r_sge,
1543                                            qp->r_len, vaddr, rkey,
1544                                            IB_ACCESS_REMOTE_WRITE);
1545                         if (unlikely(!ok))
1546                                 goto nack_acc;
1547                 } else {
1548                         qp->r_sge.sg_list = NULL;
1549                         qp->r_sge.sge.mr = NULL;
1550                         qp->r_sge.sge.vaddr = NULL;
1551                         qp->r_sge.sge.length = 0;
1552                         qp->r_sge.sge.sge_length = 0;
1553                 }
1554                 if (unlikely(!(qp->qp_access_flags &
1555                                IB_ACCESS_REMOTE_WRITE)))
1556                         goto nack_acc;
1557                 if (opcode == OP(RDMA_WRITE_FIRST))
1558                         goto send_middle;
1559                 else if (opcode == OP(RDMA_WRITE_ONLY))
1560                         goto send_last;
1561                 if (!ipath_get_rwqe(qp, 1))
1562                         goto rnr_nak;
1563                 goto send_last_imm;
1564
1565         case OP(RDMA_READ_REQUEST):
1566                 /* RETH comes after BTH */
1567                 if (!header_in_data)
1568                         reth = &ohdr->u.rc.reth;
1569                 else {
1570                         reth = (struct ib_reth *)data;
1571                         data += sizeof(*reth);
1572                 }
1573                 if (unlikely(!(qp->qp_access_flags &
1574                                IB_ACCESS_REMOTE_READ)))
1575                         goto nack_acc;
1576                 spin_lock_irq(&qp->s_lock);
1577                 qp->s_rdma_len = be32_to_cpu(reth->length);
1578                 if (qp->s_rdma_len != 0) {
1579                         u32 rkey = be32_to_cpu(reth->rkey);
1580                         u64 vaddr = be64_to_cpu(reth->vaddr);
1581                         int ok;
1582
1583                         /* Check rkey & NAK */
1584                         ok = ipath_rkey_ok(qp, &qp->s_rdma_sge,
1585                                            qp->s_rdma_len, vaddr, rkey,
1586                                            IB_ACCESS_REMOTE_READ);
1587                         if (unlikely(!ok)) {
1588                                 spin_unlock_irq(&qp->s_lock);
1589                                 goto nack_acc;
1590                         }
1591                         /*
1592                          * Update the next expected PSN.  We add 1 later
1593                          * below, so only add the remainder here.
1594                          */
1595                         if (qp->s_rdma_len > pmtu)
1596                                 qp->r_psn += (qp->s_rdma_len - 1) / pmtu;
1597                 } else {
1598                         qp->s_rdma_sge.sg_list = NULL;
1599                         qp->s_rdma_sge.num_sge = 0;
1600                         qp->s_rdma_sge.sge.mr = NULL;
1601                         qp->s_rdma_sge.sge.vaddr = NULL;
1602                         qp->s_rdma_sge.sge.length = 0;
1603                         qp->s_rdma_sge.sge.sge_length = 0;
1604                 }
1605                 /*
1606                  * We need to increment the MSN here instead of when we
1607                  * finish sending the result since a duplicate request would
1608                  * increment it more than once.
1609                  */
1610                 qp->r_msn++;
1611
1612                 qp->s_ack_state = opcode;
1613                 qp->s_ack_psn = psn;
1614                 spin_unlock_irq(&qp->s_lock);
1615
1616                 qp->r_psn++;
1617                 qp->r_state = opcode;
1618                 qp->r_nak_state = 0;
1619
1620                 /* Call ipath_do_rc_send() in another thread. */
1621                 tasklet_hi_schedule(&qp->s_task);
1622
1623                 goto done;
1624
1625         case OP(COMPARE_SWAP):
1626         case OP(FETCH_ADD): {
1627                 struct ib_atomic_eth *ateth;
1628                 u64 vaddr;
1629                 u64 sdata;
1630                 u32 rkey;
1631
1632                 if (!header_in_data)
1633                         ateth = &ohdr->u.atomic_eth;
1634                 else {
1635                         ateth = (struct ib_atomic_eth *)data;
1636                         data += sizeof(*ateth);
1637                 }
1638                 vaddr = be64_to_cpu(ateth->vaddr);
1639                 if (unlikely(vaddr & (sizeof(u64) - 1)))
1640                         goto nack_inv;
1641                 rkey = be32_to_cpu(ateth->rkey);
1642                 /* Check rkey & NAK */
1643                 if (unlikely(!ipath_rkey_ok(qp, &qp->r_sge,
1644                                             sizeof(u64), vaddr, rkey,
1645                                             IB_ACCESS_REMOTE_ATOMIC)))
1646                         goto nack_acc;
1647                 if (unlikely(!(qp->qp_access_flags &
1648                                IB_ACCESS_REMOTE_ATOMIC)))
1649                         goto nack_acc;
1650                 /* Perform atomic OP and save result. */
1651                 sdata = be64_to_cpu(ateth->swap_data);
1652                 spin_lock_irq(&dev->pending_lock);
1653                 qp->r_atomic_data = *(u64 *) qp->r_sge.sge.vaddr;
1654                 if (opcode == OP(FETCH_ADD))
1655                         *(u64 *) qp->r_sge.sge.vaddr =
1656                                 qp->r_atomic_data + sdata;
1657                 else if (qp->r_atomic_data ==
1658                          be64_to_cpu(ateth->compare_data))
1659                         *(u64 *) qp->r_sge.sge.vaddr = sdata;
1660                 spin_unlock_irq(&dev->pending_lock);
1661                 qp->r_msn++;
1662                 qp->r_atomic_psn = psn & IPATH_PSN_MASK;
1663                 psn |= 1 << 31;
1664                 break;
1665         }
1666
1667         default:
1668                 /* Drop packet for unknown opcodes. */
1669                 goto done;
1670         }
1671         qp->r_psn++;
1672         qp->r_state = opcode;
1673         qp->r_nak_state = 0;
1674         /* Send an ACK if requested or required. */
1675         if (psn & (1 << 31)) {
1676                 /*
1677                  * Coalesce ACKs unless there is a RDMA READ or
1678                  * ATOMIC pending.
1679                  */
1680                 if (qp->r_ack_state < OP(COMPARE_SWAP)) {
1681                         qp->r_ack_state = opcode;
1682                         qp->r_ack_psn = psn;
1683                 }
1684                 goto send_ack;
1685         }
1686         goto done;
1687
1688 nack_acc:
1689         /*
1690          * A NAK will ACK earlier sends and RDMA writes.
1691          * Don't queue the NAK if a RDMA read, atomic, or NAK
1692          * is pending though.
1693          */
1694         if (qp->r_ack_state < OP(COMPARE_SWAP)) {
1695                 ipath_rc_error(qp, IB_WC_REM_ACCESS_ERR);
1696                 qp->r_ack_state = OP(RDMA_WRITE_ONLY);
1697                 qp->r_nak_state = IB_NAK_REMOTE_ACCESS_ERROR;
1698                 qp->r_ack_psn = qp->r_psn;
1699         }
1700 send_ack:
1701         /* Send ACK right away unless the send tasklet has a pending ACK. */
1702         if (qp->s_ack_state == OP(ACKNOWLEDGE))
1703                 send_rc_ack(qp);
1704
1705 done:
1706         return;
1707 }