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                 len = wqe->length;
 245                 ss = &qp->s_sge;
 246                 bth2 = 0;
 247                 switch (wqe->wr.opcode) {
 248                 case IB_WR_SEND:
 249                 case IB_WR_SEND_WITH_IMM:
 250                         /* If no credit, return. */
 251                         if (qp->s_lsn != (u32) -1 &&
 252                             ipath_cmp24(wqe->ssn, qp->s_lsn + 1) > 0)
 253                                 goto done;
 254                         wqe->lpsn = wqe->psn;
 255                         if (len > pmtu) {
 256                                 wqe->lpsn += (len - 1) / pmtu;
 257                                 qp->s_state = OP(SEND_FIRST);
 258                                 len = pmtu;
 259                                 break;
 260                         }
 261                         if (wqe->wr.opcode == IB_WR_SEND)
 262                                 qp->s_state = OP(SEND_ONLY);
 263                         else {
 264                                 qp->s_state = OP(SEND_ONLY_WITH_IMMEDIATE);
 265                                 /* Immediate data comes after the BTH */
 266                                 ohdr->u.imm_data = wqe->wr.imm_data;
 267                                 hwords += 1;
 268                         }
 269                         if (wqe->wr.send_flags & IB_SEND_SOLICITED)
 270                                 bth0 |= 1 << 23;
 271                         bth2 = 1 << 31; /* Request ACK. */
 272                         if (++qp->s_cur == qp->s_size)
 273                                 qp->s_cur = 0;
 274                         break;
 275
 276                 case IB_WR_RDMA_WRITE:
 277                         if (newreq && qp->s_lsn != (u32) -1)
 278                                 qp->s_lsn++;
 279                         /* FALLTHROUGH */
 280                 case IB_WR_RDMA_WRITE_WITH_IMM:
 281                         /* If no credit, return. */
 282                         if (qp->s_lsn != (u32) -1 &&
 283                             ipath_cmp24(wqe->ssn, qp->s_lsn + 1) > 0)
 284                                 goto done;
 285                         ohdr->u.rc.reth.vaddr =
 286                                 cpu_to_be64(wqe->wr.wr.rdma.remote_addr);
 287                         ohdr->u.rc.reth.rkey =
 288                                 cpu_to_be32(wqe->wr.wr.rdma.rkey);
 289                         ohdr->u.rc.reth.length = cpu_to_be32(len);
 290                         hwords += sizeof(struct ib_reth) / 4;
 291                         wqe->lpsn = wqe->psn;
 292                         if (len > pmtu) {
 293                                 wqe->lpsn += (len - 1) / pmtu;
 294                                 qp->s_state = OP(RDMA_WRITE_FIRST);
 295                                 len = pmtu;
 296                                 break;
 297                         }
 298                         if (wqe->wr.opcode == IB_WR_RDMA_WRITE)
 299                                 qp->s_state = OP(RDMA_WRITE_ONLY);
 300                         else {
 301                                 qp->s_state =
 302                                         OP(RDMA_WRITE_ONLY_WITH_IMMEDIATE);
 303                                 /* Immediate data comes after RETH */
 304                                 ohdr->u.rc.imm_data = wqe->wr.imm_data;
 305                                 hwords += 1;
 306                                 if (wqe->wr.send_flags & IB_SEND_SOLICITED)
 307                                         bth0 |= 1 << 23;
 308                         }
 309                         bth2 = 1 << 31; /* Request ACK. */
 310                         if (++qp->s_cur == qp->s_size)
 311                                 qp->s_cur = 0;
 312                         break;
 313
 314                 case IB_WR_RDMA_READ:
 315                         ohdr->u.rc.reth.vaddr =
 316                                 cpu_to_be64(wqe->wr.wr.rdma.remote_addr);
 317                         ohdr->u.rc.reth.rkey =
 318                                 cpu_to_be32(wqe->wr.wr.rdma.rkey);
 319                         ohdr->u.rc.reth.length = cpu_to_be32(len);
 320                         qp->s_state = OP(RDMA_READ_REQUEST);
 321                         hwords += sizeof(ohdr->u.rc.reth) / 4;
 322                         if (newreq) {
 323                                 if (qp->s_lsn != (u32) -1)
 324                                         qp->s_lsn++;
 325                                 /*
 326                                  * Adjust s_next_psn to count the
 327                                  * expected number of responses.
 328                                  */
 329                                 if (len > pmtu)
 330                                         qp->s_next_psn += (len - 1) / pmtu;
 331                                 wqe->lpsn = qp->s_next_psn++;
 332                         }
 333                         ss = NULL;
 334                         len = 0;
 335                         if (++qp->s_cur == qp->s_size)
 336                                 qp->s_cur = 0;
 337                         break;
 338
 339                 case IB_WR_ATOMIC_CMP_AND_SWP:
 340                 case IB_WR_ATOMIC_FETCH_AND_ADD:
 341                         if (wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP)
 342                                 qp->s_state = OP(COMPARE_SWAP);
 343                         else
 344                                 qp->s_state = OP(FETCH_ADD);
 345                         ohdr->u.atomic_eth.vaddr = cpu_to_be64(
 346                                 wqe->wr.wr.atomic.remote_addr);
 347                         ohdr->u.atomic_eth.rkey = cpu_to_be32(
 348                                 wqe->wr.wr.atomic.rkey);
 349                         ohdr->u.atomic_eth.swap_data = cpu_to_be64(
 350                                 wqe->wr.wr.atomic.swap);
 351                         ohdr->u.atomic_eth.compare_data = cpu_to_be64(
 352                                 wqe->wr.wr.atomic.compare_add);
 353                         hwords += sizeof(struct ib_atomic_eth) / 4;
 354                         if (newreq) {
 355                                 if (qp->s_lsn != (u32) -1)
 356                                         qp->s_lsn++;
 357                                 wqe->lpsn = wqe->psn;
 358                         }
 359                         if (++qp->s_cur == qp->s_size)
 360                                 qp->s_cur = 0;
 361                         ss = NULL;
 362                         len = 0;
 363                         break;
 364
 365                 default:
 366                         goto done;
 367                 }
 368                 qp->s_sge.sge = wqe->sg_list[0];
 369                 qp->s_sge.sg_list = wqe->sg_list + 1;
 370                 qp->s_sge.num_sge = wqe->wr.num_sge;
 371                 qp->s_len = wqe->length;
 372                 if (newreq) {
 373                         qp->s_tail++;
 374                         if (qp->s_tail >= qp->s_size)
 375                                 qp->s_tail = 0;
 376                 }
 377                 bth2 |= qp->s_psn & IPATH_PSN_MASK;
 378                 if (wqe->wr.opcode == IB_WR_RDMA_READ)
 379                         qp->s_psn = wqe->lpsn + 1;
 380                 else {
 381                         qp->s_psn++;
 382                         if ((int)(qp->s_psn - qp->s_next_psn) > 0)
 383                                 qp->s_next_psn = qp->s_psn;
 384                 }
 385                 /*
 386                  * Put the QP on the pending list so lost ACKs will cause
 387                  * a retry.  More than one request can be pending so the
 388                  * QP may already be on the dev->pending list.
 389                  */
 390                 spin_lock(&dev->pending_lock);
 391                 if (list_empty(&qp->timerwait))
 392                         list_add_tail(&qp->timerwait,
 393                                       &dev->pending[dev->pending_index]);
 394                 spin_unlock(&dev->pending_lock);
 395                 break;
 396
 397         case OP(RDMA_READ_RESPONSE_FIRST):
 398                 /*
 399                  * This case can only happen if a send is restarted.
 400                  * See ipath_restart_rc().
 401                  */
 402                 ipath_init_restart(qp, wqe);
 403                 /* FALLTHROUGH */
 404         case OP(SEND_FIRST):
 405                 qp->s_state = OP(SEND_MIDDLE);
 406                 /* FALLTHROUGH */
 407         case OP(SEND_MIDDLE):
 408                 bth2 = qp->s_psn++ & IPATH_PSN_MASK;
 409                 if ((int)(qp->s_psn - qp->s_next_psn) > 0)
 410                         qp->s_next_psn = qp->s_psn;
 411                 ss = &qp->s_sge;
 412                 len = qp->s_len;
 413                 if (len > pmtu) {
 414                         len = pmtu;
 415                         break;
 416                 }
 417                 if (wqe->wr.opcode == IB_WR_SEND)
 418                         qp->s_state = OP(SEND_LAST);
 419                 else {
 420                         qp->s_state = OP(SEND_LAST_WITH_IMMEDIATE);
 421                         /* Immediate data comes after the BTH */
 422                         ohdr->u.imm_data = wqe->wr.imm_data;
 423                         hwords += 1;
 424                 }
 425                 if (wqe->wr.send_flags & IB_SEND_SOLICITED)
 426                         bth0 |= 1 << 23;
 427                 bth2 |= 1 << 31;        /* Request ACK. */
 428                 qp->s_cur++;
 429                 if (qp->s_cur >= qp->s_size)
 430                         qp->s_cur = 0;
 431                 break;
 432
 433         case OP(RDMA_READ_RESPONSE_LAST):
 434                 /*
 435                  * This case can only happen if a RDMA write is restarted.
 436                  * See ipath_restart_rc().
 437                  */
 438                 ipath_init_restart(qp, wqe);
 439                 /* FALLTHROUGH */
 440         case OP(RDMA_WRITE_FIRST):
 441                 qp->s_state = OP(RDMA_WRITE_MIDDLE);
 442                 /* FALLTHROUGH */
 443         case OP(RDMA_WRITE_MIDDLE):
 444                 bth2 = qp->s_psn++ & IPATH_PSN_MASK;
 445                 if ((int)(qp->s_psn - qp->s_next_psn) > 0)
 446                         qp->s_next_psn = qp->s_psn;
 447                 ss = &qp->s_sge;
 448                 len = qp->s_len;
 449                 if (len > pmtu) {
 450                         len = pmtu;
 451                         break;
 452                 }
 453                 if (wqe->wr.opcode == IB_WR_RDMA_WRITE)
 454                         qp->s_state = OP(RDMA_WRITE_LAST);
 455                 else {
 456                         qp->s_state = OP(RDMA_WRITE_LAST_WITH_IMMEDIATE);
 457                         /* Immediate data comes after the BTH */
 458                         ohdr->u.imm_data = wqe->wr.imm_data;
 459                         hwords += 1;
 460                         if (wqe->wr.send_flags & IB_SEND_SOLICITED)
 461                                 bth0 |= 1 << 23;
 462                 }
 463                 bth2 |= 1 << 31;        /* Request ACK. */
 464                 qp->s_cur++;
 465                 if (qp->s_cur >= qp->s_size)
 466                         qp->s_cur = 0;
 467                 break;
 468
 469         case OP(RDMA_READ_RESPONSE_MIDDLE):
 470                 /*
 471                  * This case can only happen if a RDMA read is restarted.
 472                  * See ipath_restart_rc().
 473                  */
 474                 ipath_init_restart(qp, wqe);
 475                 len = ((qp->s_psn - wqe->psn) & IPATH_PSN_MASK) * pmtu;
 476                 ohdr->u.rc.reth.vaddr =
 477                         cpu_to_be64(wqe->wr.wr.rdma.remote_addr + len);
 478                 ohdr->u.rc.reth.rkey =
 479                         cpu_to_be32(wqe->wr.wr.rdma.rkey);
 480                 ohdr->u.rc.reth.length = cpu_to_be32(qp->s_len);
 481                 qp->s_state = OP(RDMA_READ_REQUEST);
 482                 hwords += sizeof(ohdr->u.rc.reth) / 4;
 483                 bth2 = qp->s_psn++ & IPATH_PSN_MASK;
 484                 if ((int)(qp->s_psn - qp->s_next_psn) > 0)
 485                         qp->s_next_psn = qp->s_psn;
 486                 ss = NULL;
 487                 len = 0;
 488                 qp->s_cur++;
 489                 if (qp->s_cur == qp->s_size)
 490                         qp->s_cur = 0;
 491                 break;
 492
 493         case OP(RDMA_READ_REQUEST):
 494         case OP(COMPARE_SWAP):
 495         case OP(FETCH_ADD):
 496                 /*
 497                  * We shouldn't start anything new until this request is
 498                  * finished.  The ACK will handle rescheduling us.  XXX The
 499                  * number of outstanding ones is negotiated at connection
 500                  * setup time (see pg. 258,289)?  XXX Also, if we support
 501                  * multiple outstanding requests, we need to check the WQE
 502                  * IB_SEND_FENCE flag and not send a new request if a RDMA
 503                  * read or atomic is pending.
 504                  */
 505                 goto done;
 506         }
 507         if (ipath_cmp24(qp->s_psn, qp->s_last_psn + IPATH_PSN_CREDIT - 1) >= 0)
 508                 bth2 |= 1 << 31;        /* Request ACK. */
 509         qp->s_len -= len;
 510         qp->s_hdrwords = hwords;
 511         qp->s_cur_sge = ss;
 512         qp->s_cur_size = len;
 513         *bth0p = bth0 | (qp->s_state << 24);
 514         *bth2p = bth2;
 515         return 1;
 516
 517 done:
 518         return 0;
 519 }
 520
 521 /**
 522  * send_rc_ack - Construct an ACK packet and send it
 523  * @qp: a pointer to the QP
 524  *
 525  * This is called from ipath_rc_rcv() and only uses the receive
 526  * side QP state.
 527  * Note that RDMA reads are handled in the send side QP state and tasklet.
 528  */
 529 static void send_rc_ack(struct ipath_qp *qp)
 530 {
 531         struct ipath_ibdev *dev = to_idev(qp->ibqp.device);
 532         u16 lrh0;
 533         u32 bth0;
 534         u32 hwords;
 535         struct ipath_ib_header hdr;
 536         struct ipath_other_headers *ohdr;
 537
 538         /* Construct the header. */
 539         ohdr = &hdr.u.oth;
 540         lrh0 = IPATH_LRH_BTH;
 541         /* header size in 32-bit words LRH+BTH+AETH = (8+12+4)/4. */
 542         hwords = 6;
 543         if (unlikely(qp->remote_ah_attr.ah_flags & IB_AH_GRH)) {
 544                 hwords += ipath_make_grh(dev, &hdr.u.l.grh,
 545                                          &qp->remote_ah_attr.grh,
 546                                          hwords, 0);
 547                 ohdr = &hdr.u.l.oth;
 548                 lrh0 = IPATH_LRH_GRH;
 549         }
 550         /* read pkey_index w/o lock (its atomic) */
 551         bth0 = ipath_get_pkey(dev->dd, qp->s_pkey_index);
 552         if (qp->r_nak_state)
 553                 ohdr->u.aeth = cpu_to_be32((qp->r_msn & IPATH_MSN_MASK) |
 554                                             (qp->r_nak_state <<
 555                                              IPATH_AETH_CREDIT_SHIFT));
 556         else
 557                 ohdr->u.aeth = ipath_compute_aeth(qp);
 558         if (qp->r_ack_state >= OP(COMPARE_SWAP)) {
 559                 bth0 |= OP(ATOMIC_ACKNOWLEDGE) << 24;
 560                 ohdr->u.at.atomic_ack_eth = cpu_to_be64(qp->r_atomic_data);
 561                 hwords += sizeof(ohdr->u.at.atomic_ack_eth) / 4;
 562         } else
 563                 bth0 |= OP(ACKNOWLEDGE) << 24;
 564         lrh0 |= qp->remote_ah_attr.sl << 4;
 565         hdr.lrh[0] = cpu_to_be16(lrh0);
 566         hdr.lrh[1] = cpu_to_be16(qp->remote_ah_attr.dlid);
 567         hdr.lrh[2] = cpu_to_be16(hwords + SIZE_OF_CRC);
 568         hdr.lrh[3] = cpu_to_be16(dev->dd->ipath_lid);
 569         ohdr->bth[0] = cpu_to_be32(bth0);
 570         ohdr->bth[1] = cpu_to_be32(qp->remote_qpn);
 571         ohdr->bth[2] = cpu_to_be32(qp->r_ack_psn & IPATH_PSN_MASK);
 572
 573         /*
 574          * If we can send the ACK, clear the ACK state.
 575          */
 576         if (ipath_verbs_send(dev->dd, hwords, (u32 *) &hdr, 0, NULL) == 0) {
 577                 qp->r_ack_state = OP(ACKNOWLEDGE);
 578                 dev->n_unicast_xmit++;
 579         } else {
 580                 /*
 581                  * We are out of PIO buffers at the moment.
 582                  * Pass responsibility for sending the ACK to the
 583                  * send tasklet so that when a PIO buffer becomes
 584                  * available, the ACK is sent ahead of other outgoing
 585                  * packets.
 586                  */
 587                 dev->n_rc_qacks++;
 588                 spin_lock_irq(&qp->s_lock);
 589                 /* Don't coalesce if a RDMA read or atomic is pending. */
 590                 if (qp->s_ack_state == OP(ACKNOWLEDGE) ||
 591                     qp->s_ack_state < OP(RDMA_READ_REQUEST)) {
 592                         qp->s_ack_state = qp->r_ack_state;
 593                         qp->s_nak_state = qp->r_nak_state;
 594                         qp->s_ack_psn = qp->r_ack_psn;
 595                         qp->r_ack_state = OP(ACKNOWLEDGE);
 596                 }
 597                 spin_unlock_irq(&qp->s_lock);
 598
 599                 /* Call ipath_do_rc_send() in another thread. */
 600                 tasklet_hi_schedule(&qp->s_task);
 601         }
 602 }
 603
 604 /**
 605  * reset_psn - reset the QP state to send starting from PSN
 606  * @qp: the QP
 607  * @psn: the packet sequence number to restart at
 608  *
 609  * This is called from ipath_rc_rcv() to process an incoming RC ACK
 610  * for the given QP.
 611  * Called at interrupt level with the QP s_lock held.
 612  */
 613 static void reset_psn(struct ipath_qp *qp, u32 psn)
 614 {
 615         u32 n = qp->s_last;
 616         struct ipath_swqe *wqe = get_swqe_ptr(qp, n);
 617         u32 opcode;
 618
 619         qp->s_cur = n;
 620
 621         /*
 622          * If we are starting the request from the beginning,
 623          * let the normal send code handle initialization.
 624          */
 625         if (ipath_cmp24(psn, wqe->psn) <= 0) {
 626                 qp->s_state = OP(SEND_LAST);
 627                 goto done;
 628         }
 629
 630         /* Find the work request opcode corresponding to the given PSN. */
 631         opcode = wqe->wr.opcode;
 632         for (;;) {
 633                 int diff;
 634
 635                 if (++n == qp->s_size)
 636                         n = 0;
 637                 if (n == qp->s_tail)
 638                         break;
 639                 wqe = get_swqe_ptr(qp, n);
 640                 diff = ipath_cmp24(psn, wqe->psn);
 641                 if (diff < 0)
 642                         break;
 643                 qp->s_cur = n;
 644                 /*
 645                  * If we are starting the request from the beginning,
 646                  * let the normal send code handle initialization.
 647                  */
 648                 if (diff == 0) {
 649                         qp->s_state = OP(SEND_LAST);
 650                         goto done;
 651                 }
 652                 opcode = wqe->wr.opcode;
 653         }
 654
 655         /*
 656          * Set the state to restart in the middle of a request.
 657          * Don't change the s_sge, s_cur_sge, or s_cur_size.
 658          * See ipath_do_rc_send().
 659          */
 660         switch (opcode) {
 661         case IB_WR_SEND:
 662         case IB_WR_SEND_WITH_IMM:
 663                 qp->s_state = OP(RDMA_READ_RESPONSE_FIRST);
 664                 break;
 665
 666         case IB_WR_RDMA_WRITE:
 667         case IB_WR_RDMA_WRITE_WITH_IMM:
 668                 qp->s_state = OP(RDMA_READ_RESPONSE_LAST);
 669                 break;
 670
 671         case IB_WR_RDMA_READ:
 672                 qp->s_state = OP(RDMA_READ_RESPONSE_MIDDLE);
 673                 break;
 674
 675         default:
 676                 /*
 677                  * This case shouldn't happen since its only
 678                  * one PSN per req.
 679                  */
 680                 qp->s_state = OP(SEND_LAST);
 681         }
 682 done:
 683         qp->s_psn = psn;
 684 }
 685
 686 /**
 687  * ipath_restart_rc - back up requester to resend the last un-ACKed request
 688  * @qp: the QP to restart
 689  * @psn: packet sequence number for the request
 690  * @wc: the work completion request
 691  *
 692  * The QP s_lock should be held and interrupts disabled.
 693  */
 694 void ipath_restart_rc(struct ipath_qp *qp, u32 psn, struct ib_wc *wc)
 695 {
 696         struct ipath_swqe *wqe = get_swqe_ptr(qp, qp->s_last);
 697         struct ipath_ibdev *dev;
 698
 699         if (qp->s_retry == 0) {
 700                 wc->wr_id = wqe->wr.wr_id;
 701                 wc->status = IB_WC_RETRY_EXC_ERR;
 702                 wc->opcode = ib_ipath_wc_opcode[wqe->wr.opcode];
 703                 wc->vendor_err = 0;
 704                 wc->byte_len = 0;
 705                 wc->qp_num = qp->ibqp.qp_num;
 706                 wc->src_qp = qp->remote_qpn;
 707                 wc->pkey_index = 0;
 708                 wc->slid = qp->remote_ah_attr.dlid;
 709                 wc->sl = qp->remote_ah_attr.sl;
 710                 wc->dlid_path_bits = 0;
 711                 wc->port_num = 0;
 712                 ipath_sqerror_qp(qp, wc);
 713                 goto bail;
 714         }
 715         qp->s_retry--;
 716
 717         /*
 718          * Remove the QP from the timeout queue.
 719          * Note: it may already have been removed by ipath_ib_timer().
 720          */
 721         dev = to_idev(qp->ibqp.device);
 722         spin_lock(&dev->pending_lock);
 723         if (!list_empty(&qp->timerwait))
 724                 list_del_init(&qp->timerwait);
 725         spin_unlock(&dev->pending_lock);
 726
 727         if (wqe->wr.opcode == IB_WR_RDMA_READ)
 728                 dev->n_rc_resends++;
 729         else
 730                 dev->n_rc_resends += (int)qp->s_psn - (int)psn;
 731
 732         reset_psn(qp, psn);
 733         tasklet_hi_schedule(&qp->s_task);
 734
 735 bail:
 736         return;
 737 }
 738
 739 static inline void update_last_psn(struct ipath_qp *qp, u32 psn)
 740 {
 741         if (qp->s_wait_credit) {
 742                 qp->s_wait_credit = 0;
 743                 tasklet_hi_schedule(&qp->s_task);
 744         }
 745         qp->s_last_psn = psn;
 746 }
 747
 748 /**
 749  * do_rc_ack - process an incoming RC ACK
 750  * @qp: the QP the ACK came in on
 751  * @psn: the packet sequence number of the ACK
 752  * @opcode: the opcode of the request that resulted in the ACK
 753  *
 754  * This is called from ipath_rc_rcv_resp() to process an incoming RC ACK
 755  * for the given QP.
 756  * Called at interrupt level with the QP s_lock held and interrupts disabled.
 757  * Returns 1 if OK, 0 if current operation should be aborted (NAK).
 758  */
 759 static int do_rc_ack(struct ipath_qp *qp, u32 aeth, u32 psn, int opcode)
 760 {
 761         struct ipath_ibdev *dev = to_idev(qp->ibqp.device);
 762         struct ib_wc wc;
 763         struct ipath_swqe *wqe;
 764         int ret = 0;
 765         u32 ack_psn;
 766
 767         /*
 768          * Remove the QP from the timeout queue (or RNR timeout queue).
 769          * If ipath_ib_timer() has already removed it,
 770          * it's OK since we hold the QP s_lock and ipath_restart_rc()
 771          * just won't find anything to restart if we ACK everything.
 772          */
 773         spin_lock(&dev->pending_lock);
 774         if (!list_empty(&qp->timerwait))
 775                 list_del_init(&qp->timerwait);
 776         spin_unlock(&dev->pending_lock);
 777
 778         /* Nothing is pending to ACK/NAK. */
 779         if (unlikely(qp->s_last == qp->s_tail))
 780                 goto bail;
 781
 782         /*
 783          * Note that NAKs implicitly ACK outstanding SEND and RDMA write
 784          * requests and implicitly NAK RDMA read and atomic requests issued
 785          * before the NAK'ed request.  The MSN won't include the NAK'ed
 786          * request but will include an ACK'ed request(s).
 787          */
 788         ack_psn = psn;
 789         if (aeth >> 29)
 790                 ack_psn--;
 791         wqe = get_swqe_ptr(qp, qp->s_last);
 792
 793         /*
 794          * The MSN might be for a later WQE than the PSN indicates so
 795          * only complete WQEs that the PSN finishes.
 796          */
 797         while (ipath_cmp24(ack_psn, wqe->lpsn) >= 0) {
 798                 /*
 799                  * If this request is a RDMA read or atomic, and the ACK is
 800                  * for a later operation, this ACK NAKs the RDMA read or
 801                  * atomic.  In other words, only a RDMA_READ_LAST or ONLY
 802                  * can ACK a RDMA read and likewise for atomic ops.  Note
 803                  * that the NAK case can only happen if relaxed ordering is
 804                  * used and requests are sent after an RDMA read or atomic
 805                  * is sent but before the response is received.
 806                  */
 807                 if ((wqe->wr.opcode == IB_WR_RDMA_READ &&
 808                      (opcode != OP(RDMA_READ_RESPONSE_LAST) ||
 809                        ipath_cmp24(ack_psn, wqe->lpsn) != 0)) ||
 810                     ((wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP ||
 811                       wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD) &&
 812                      (opcode != OP(ATOMIC_ACKNOWLEDGE) ||
 813                       ipath_cmp24(wqe->psn, psn) != 0))) {
 814                         /*
 815                          * The last valid PSN seen is the previous
 816                          * request's.
 817                          */
 818                         update_last_psn(qp, wqe->psn - 1);
 819                         /* Retry this request. */
 820                         ipath_restart_rc(qp, wqe->psn, &wc);
 821                         /*
 822                          * No need to process the ACK/NAK since we are
 823                          * restarting an earlier request.
 824                          */
 825                         goto bail;
 826                 }
 827                 if (wqe->wr.opcode == IB_WR_RDMA_READ ||
 828                     wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP ||
 829                     wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD)
 830                         tasklet_hi_schedule(&qp->s_task);
 831                 /* Post a send completion queue entry if requested. */
 832                 if (!test_bit(IPATH_S_SIGNAL_REQ_WR, &qp->s_flags) ||
 833                     (wqe->wr.send_flags & IB_SEND_SIGNALED)) {
 834                         wc.wr_id = wqe->wr.wr_id;
 835                         wc.status = IB_WC_SUCCESS;
 836                         wc.opcode = ib_ipath_wc_opcode[wqe->wr.opcode];
 837                         wc.vendor_err = 0;
 838                         wc.byte_len = wqe->length;
 839                         wc.qp_num = qp->ibqp.qp_num;
 840                         wc.src_qp = qp->remote_qpn;
 841                         wc.pkey_index = 0;
 842                         wc.slid = qp->remote_ah_attr.dlid;
 843                         wc.sl = qp->remote_ah_attr.sl;
 844                         wc.dlid_path_bits = 0;
 845                         wc.port_num = 0;
 846                         ipath_cq_enter(to_icq(qp->ibqp.send_cq), &wc, 0);
 847                 }
 848                 qp->s_retry = qp->s_retry_cnt;
 849                 /*
 850                  * If we are completing a request which is in the process of
 851                  * being resent, we can stop resending it since we know the
 852                  * responder has already seen it.
 853                  */
 854                 if (qp->s_last == qp->s_cur) {
 855                         if (++qp->s_cur >= qp->s_size)
 856                                 qp->s_cur = 0;
 857                         wqe = get_swqe_ptr(qp, qp->s_cur);
 858                         qp->s_state = OP(SEND_LAST);
 859                         qp->s_psn = wqe->psn;
 860                 }
 861                 if (++qp->s_last >= qp->s_size)
 862                         qp->s_last = 0;
 863                 wqe = get_swqe_ptr(qp, qp->s_last);
 864                 if (qp->s_last == qp->s_tail)
 865                         break;
 866         }
 867
 868         switch (aeth >> 29) {
 869         case 0:         /* ACK */
 870                 dev->n_rc_acks++;
 871                 /* If this is a partial ACK, reset the retransmit timer. */
 872                 if (qp->s_last != qp->s_tail) {
 873                         spin_lock(&dev->pending_lock);
 874                         list_add_tail(&qp->timerwait,
 875                                       &dev->pending[dev->pending_index]);
 876                         spin_unlock(&dev->pending_lock);
 877                 }
 878                 ipath_get_credit(qp, aeth);
 879                 qp->s_rnr_retry = qp->s_rnr_retry_cnt;
 880                 qp->s_retry = qp->s_retry_cnt;
 881                 update_last_psn(qp, psn);
 882                 ret = 1;
 883                 goto bail;
 884
 885         case 1:         /* RNR NAK */
 886                 dev->n_rnr_naks++;
 887                 if (qp->s_rnr_retry == 0) {
 888                         if (qp->s_last == qp->s_tail)
 889                                 goto bail;
 890
 891                         wc.status = IB_WC_RNR_RETRY_EXC_ERR;
 892                         goto class_b;
 893                 }
 894                 if (qp->s_rnr_retry_cnt < 7)
 895                         qp->s_rnr_retry--;
 896                 if (qp->s_last == qp->s_tail)
 897                         goto bail;
 898
 899                 /* The last valid PSN is the previous PSN. */
 900                 update_last_psn(qp, psn - 1);
 901
 902                 dev->n_rc_resends += (int)qp->s_psn - (int)psn;
 903
 904                 reset_psn(qp, psn);
 905
 906                 qp->s_rnr_timeout =
 907                         ib_ipath_rnr_table[(aeth >> IPATH_AETH_CREDIT_SHIFT) &
 908                                            IPATH_AETH_CREDIT_MASK];
 909                 ipath_insert_rnr_queue(qp);
 910                 goto bail;
 911
 912         case 3:         /* NAK */
 913                 /* The last valid PSN seen is the previous request's. */
 914                 if (qp->s_last != qp->s_tail)
 915                         update_last_psn(qp, wqe->psn - 1);
 916                 switch ((aeth >> IPATH_AETH_CREDIT_SHIFT) &
 917                         IPATH_AETH_CREDIT_MASK) {
 918                 case 0: /* PSN sequence error */
 919                         dev->n_seq_naks++;
 920                         /*
 921                          * Back up to the responder's expected PSN.  XXX
 922                          * Note that we might get a NAK in the middle of an
 923                          * RDMA READ response which terminates the RDMA
 924                          * READ.
 925                          */
 926                         if (qp->s_last == qp->s_tail)
 927                                 break;
 928
 929                         if (ipath_cmp24(psn, wqe->psn) < 0)
 930                                 break;
 931
 932                         /* Retry the request. */
 933                         ipath_restart_rc(qp, psn, &wc);
 934                         break;
 935
 936                 case 1: /* Invalid Request */
 937                         wc.status = IB_WC_REM_INV_REQ_ERR;
 938                         dev->n_other_naks++;
 939                         goto class_b;
 940
 941                 case 2: /* Remote Access Error */
 942                         wc.status = IB_WC_REM_ACCESS_ERR;
 943                         dev->n_other_naks++;
 944                         goto class_b;
 945
 946                 case 3: /* Remote Operation Error */
 947                         wc.status = IB_WC_REM_OP_ERR;
 948                         dev->n_other_naks++;
 949                 class_b:
 950                         wc.wr_id = wqe->wr.wr_id;
 951                         wc.opcode = ib_ipath_wc_opcode[wqe->wr.opcode];
 952                         wc.vendor_err = 0;
 953                         wc.byte_len = 0;
 954                         wc.qp_num = qp->ibqp.qp_num;
 955                         wc.src_qp = qp->remote_qpn;
 956                         wc.pkey_index = 0;
 957                         wc.slid = qp->remote_ah_attr.dlid;
 958                         wc.sl = qp->remote_ah_attr.sl;
 959                         wc.dlid_path_bits = 0;
 960                         wc.port_num = 0;
 961                         ipath_sqerror_qp(qp, &wc);
 962                         break;
 963
 964                 default:
 965                         /* Ignore other reserved NAK error codes */
 966                         goto reserved;
 967                 }
 968                 qp->s_rnr_retry = qp->s_rnr_retry_cnt;
 969                 goto bail;
 970
 971         default:                /* 2: reserved */
 972         reserved:
 973                 /* Ignore reserved NAK codes. */
 974                 goto bail;
 975         }
 976
 977 bail:
 978         return ret;
 979 }
 980
 981 /**
 982  * ipath_rc_rcv_resp - process an incoming RC response packet
 983  * @dev: the device this packet came in on
 984  * @ohdr: the other headers for this packet
 985  * @data: the packet data
 986  * @tlen: the packet length
 987  * @qp: the QP for this packet
 988  * @opcode: the opcode for this packet
 989  * @psn: the packet sequence number for this packet
 990  * @hdrsize: the header length
 991  * @pmtu: the path MTU
 992  * @header_in_data: true if part of the header data is in the data buffer
 993  *
 994  * This is called from ipath_rc_rcv() to process an incoming RC response
 995  * packet for the given QP.
 996  * Called at interrupt level.
 997  */
 998 static inline void ipath_rc_rcv_resp(struct ipath_ibdev *dev,
 999                                      struct ipath_other_headers *ohdr,
1000                                      void *data, u32 tlen,
1001                                      struct ipath_qp *qp,
1002                                      u32 opcode,
1003                                      u32 psn, u32 hdrsize, u32 pmtu,
1004                                      int header_in_data)
1005 {
1006         unsigned long flags;
1007         struct ib_wc wc;
1008         int diff;
1009         u32 pad;
1010         u32 aeth;
1011
1012         spin_lock_irqsave(&qp->s_lock, flags);
1013
1014         /* Ignore invalid responses. */
1015         if (ipath_cmp24(psn, qp->s_next_psn) >= 0)
1016                 goto ack_done;
1017
1018         /* Ignore duplicate responses. */
1019         diff = ipath_cmp24(psn, qp->s_last_psn);
1020         if (unlikely(diff <= 0)) {
1021                 /* Update credits for "ghost" ACKs */
1022                 if (diff == 0 && opcode == OP(ACKNOWLEDGE)) {
1023                         if (!header_in_data)
1024                                 aeth = be32_to_cpu(ohdr->u.aeth);
1025                         else {
1026                                 aeth = be32_to_cpu(((__be32 *) data)[0]);
1027                                 data += sizeof(__be32);
1028                         }
1029                         if ((aeth >> 29) == 0)
1030                                 ipath_get_credit(qp, aeth);
1031                 }
1032                 goto ack_done;
1033         }
1034
1035         switch (opcode) {
1036         case OP(ACKNOWLEDGE):
1037         case OP(ATOMIC_ACKNOWLEDGE):
1038         case OP(RDMA_READ_RESPONSE_FIRST):
1039                 if (!header_in_data)
1040                         aeth = be32_to_cpu(ohdr->u.aeth);
1041                 else {
1042                         aeth = be32_to_cpu(((__be32 *) data)[0]);
1043                         data += sizeof(__be32);
1044                 }
1045                 if (opcode == OP(ATOMIC_ACKNOWLEDGE))
1046                         *(u64 *) qp->s_sge.sge.vaddr = *(u64 *) data;
1047                 if (!do_rc_ack(qp, aeth, psn, opcode) ||
1048                     opcode != OP(RDMA_READ_RESPONSE_FIRST))
1049                         goto ack_done;
1050                 hdrsize += 4;
1051                 /*
1052                  * do_rc_ack() has already checked the PSN so skip
1053                  * the sequence check.
1054                  */
1055                 goto rdma_read;
1056
1057         case OP(RDMA_READ_RESPONSE_MIDDLE):
1058                 /* no AETH, no ACK */
1059                 if (unlikely(ipath_cmp24(psn, qp->s_last_psn + 1))) {
1060                         dev->n_rdma_seq++;
1061                         if (qp->s_last != qp->s_tail)
1062                                 ipath_restart_rc(qp, qp->s_last_psn + 1, &wc);
1063                         goto ack_done;
1064                 }
1065         rdma_read:
1066                 if (unlikely(qp->s_state != OP(RDMA_READ_REQUEST)))
1067                         goto ack_done;
1068                 if (unlikely(tlen != (hdrsize + pmtu + 4)))
1069                         goto ack_done;
1070                 if (unlikely(pmtu >= qp->s_len))
1071                         goto ack_done;
1072                 /* We got a response so update the timeout. */
1073                 if (unlikely(qp->s_last == qp->s_tail ||
1074                              get_swqe_ptr(qp, qp->s_last)->wr.opcode !=
1075                              IB_WR_RDMA_READ))
1076                         goto ack_done;
1077                 spin_lock(&dev->pending_lock);
1078                 if (qp->s_rnr_timeout == 0 && !list_empty(&qp->timerwait))
1079                         list_move_tail(&qp->timerwait,
1080                                        &dev->pending[dev->pending_index]);
1081                 spin_unlock(&dev->pending_lock);
1082                 /*
1083                  * Update the RDMA receive state but do the copy w/o
1084                  * holding the locks and blocking interrupts.
1085                  * XXX Yet another place that affects relaxed RDMA order
1086                  * since we don't want s_sge modified.
1087                  */
1088                 qp->s_len -= pmtu;
1089                 update_last_psn(qp, psn);
1090                 spin_unlock_irqrestore(&qp->s_lock, flags);
1091                 ipath_copy_sge(&qp->s_sge, data, pmtu);
1092                 goto bail;
1093
1094         case OP(RDMA_READ_RESPONSE_LAST):
1095                 /* ACKs READ req. */
1096                 if (unlikely(ipath_cmp24(psn, qp->s_last_psn + 1))) {
1097                         dev->n_rdma_seq++;
1098                         if (qp->s_last != qp->s_tail)
1099                                 ipath_restart_rc(qp, qp->s_last_psn + 1, &wc);
1100                         goto ack_done;
1101                 }
1102                 /* FALLTHROUGH */
1103         case OP(RDMA_READ_RESPONSE_ONLY):
1104                 if (unlikely(qp->s_state != OP(RDMA_READ_REQUEST)))
1105                         goto ack_done;
1106                 /*
1107                  * Get the number of bytes the message was padded by.
1108                  */
1109                 pad = (be32_to_cpu(ohdr->bth[0]) >> 20) & 3;
1110                 /*
1111                  * Check that the data size is >= 1 && <= pmtu.
1112                  * Remember to account for the AETH header (4) and
1113                  * ICRC (4).
1114                  */
1115                 if (unlikely(tlen <= (hdrsize + pad + 8))) {
1116                         /* XXX Need to generate an error CQ entry. */
1117                         goto ack_done;
1118                 }
1119                 tlen -= hdrsize + pad + 8;
1120                 if (unlikely(tlen != qp->s_len)) {
1121                         /* XXX Need to generate an error CQ entry. */
1122                         goto ack_done;
1123                 }
1124                 if (!header_in_data)
1125                         aeth = be32_to_cpu(ohdr->u.aeth);
1126                 else {
1127                         aeth = be32_to_cpu(((__be32 *) data)[0]);
1128                         data += sizeof(__be32);
1129                 }
1130                 ipath_copy_sge(&qp->s_sge, data, tlen);
1131                 if (do_rc_ack(qp, aeth, psn, OP(RDMA_READ_RESPONSE_LAST))) {
1132                         /*
1133                          * Change the state so we contimue
1134                          * processing new requests and wake up the
1135                          * tasklet if there are posted sends.
1136                          */
1137                         qp->s_state = OP(SEND_LAST);
1138                         if (qp->s_tail != qp->s_head)
1139                                 tasklet_hi_schedule(&qp->s_task);
1140                 }
1141                 goto ack_done;
1142         }
1143
1144 ack_done:
1145         spin_unlock_irqrestore(&qp->s_lock, flags);
1146 bail:
1147         return;
1148 }
1149
1150 /**
1151  * ipath_rc_rcv_error - process an incoming duplicate or error RC packet
1152  * @dev: the device this packet came in on
1153  * @ohdr: the other headers for this packet
1154  * @data: the packet data
1155  * @qp: the QP for this packet
1156  * @opcode: the opcode for this packet
1157  * @psn: the packet sequence number for this packet
1158  * @diff: the difference between the PSN and the expected PSN
1159  * @header_in_data: true if part of the header data is in the data buffer
1160  *
1161  * This is called from ipath_rc_rcv() to process an unexpected
1162  * incoming RC packet for the given QP.
1163  * Called at interrupt level.
1164  * Return 1 if no more processing is needed; otherwise return 0 to
1165  * schedule a response to be sent and the s_lock unlocked.
1166  */
1167 static inline int ipath_rc_rcv_error(struct ipath_ibdev *dev,
1168                                      struct ipath_other_headers *ohdr,
1169                                      void *data,
1170                                      struct ipath_qp *qp,
1171                                      u32 opcode,
1172                                      u32 psn,
1173                                      int diff,
1174                                      int header_in_data)
1175 {
1176         struct ib_reth *reth;
1177
1178         if (diff > 0) {
1179                 /*
1180                  * Packet sequence error.
1181                  * A NAK will ACK earlier sends and RDMA writes.
1182                  * Don't queue the NAK if a RDMA read, atomic, or
1183                  * NAK is pending though.
1184                  */
1185                 if (qp->s_ack_state != OP(ACKNOWLEDGE) ||
1186                     qp->r_nak_state != 0)
1187                         goto done;
1188                 if (qp->r_ack_state < OP(COMPARE_SWAP)) {
1189                         qp->r_ack_state = OP(SEND_ONLY);
1190                         qp->r_nak_state = IB_NAK_PSN_ERROR;
1191                         /* Use the expected PSN. */
1192                         qp->r_ack_psn = qp->r_psn;
1193                 }
1194                 goto send_ack;
1195         }
1196
1197         /*
1198          * Handle a duplicate request.  Don't re-execute SEND, RDMA
1199          * write or atomic op.  Don't NAK errors, just silently drop
1200          * the duplicate request.  Note that r_sge, r_len, and
1201          * r_rcv_len may be in use so don't modify them.
1202          *
1203          * We are supposed to ACK the earliest duplicate PSN but we
1204          * can coalesce an outstanding duplicate ACK.  We have to
1205          * send the earliest so that RDMA reads can be restarted at
1206          * the requester's expected PSN.
1207          */
1208         if (opcode == OP(RDMA_READ_REQUEST)) {
1209                 /* RETH comes after BTH */
1210                 if (!header_in_data)
1211                         reth = &ohdr->u.rc.reth;
1212                 else {
1213                         reth = (struct ib_reth *)data;
1214                         data += sizeof(*reth);
1215                 }
1216                 /*
1217                  * If we receive a duplicate RDMA request, it means the
1218                  * requester saw a sequence error and needs to restart
1219                  * from an earlier point.  We can abort the current
1220                  * RDMA read send in that case.
1221                  */
1222                 spin_lock_irq(&qp->s_lock);
1223                 if (qp->s_ack_state != OP(ACKNOWLEDGE) &&
1224                     (qp->s_hdrwords || ipath_cmp24(psn, qp->s_ack_psn) >= 0)) {
1225                         /*
1226                          * We are already sending earlier requested data.
1227                          * Don't abort it to send later out of sequence data.
1228                          */
1229                         spin_unlock_irq(&qp->s_lock);
1230                         goto done;
1231                 }
1232                 qp->s_rdma_len = be32_to_cpu(reth->length);
1233                 if (qp->s_rdma_len != 0) {
1234                         u32 rkey = be32_to_cpu(reth->rkey);
1235                         u64 vaddr = be64_to_cpu(reth->vaddr);
1236                         int ok;
1237
1238                         /*
1239                          * Address range must be a subset of the original
1240                          * request and start on pmtu boundaries.
1241                          */
1242                         ok = ipath_rkey_ok(qp, &qp->s_rdma_sge,
1243                                            qp->s_rdma_len, vaddr, rkey,
1244                                            IB_ACCESS_REMOTE_READ);
1245                         if (unlikely(!ok)) {
1246                                 spin_unlock_irq(&qp->s_lock);
1247                                 goto done;
1248                         }
1249                 } else {
1250                         qp->s_rdma_sge.sg_list = NULL;
1251                         qp->s_rdma_sge.num_sge = 0;
1252                         qp->s_rdma_sge.sge.mr = NULL;
1253                         qp->s_rdma_sge.sge.vaddr = NULL;
1254                         qp->s_rdma_sge.sge.length = 0;
1255                         qp->s_rdma_sge.sge.sge_length = 0;
1256                 }
1257                 qp->s_ack_state = opcode;
1258                 qp->s_ack_psn = psn;
1259                 spin_unlock_irq(&qp->s_lock);
1260                 tasklet_hi_schedule(&qp->s_task);
1261                 goto send_ack;
1262         }
1263
1264         /*
1265          * A pending RDMA read will ACK anything before it so
1266          * ignore earlier duplicate requests.
1267          */
1268         if (qp->s_ack_state != OP(ACKNOWLEDGE))
1269                 goto done;
1270
1271         /*
1272          * If an ACK is pending, don't replace the pending ACK
1273          * with an earlier one since the later one will ACK the earlier.
1274          * Also, if we already have a pending atomic, send it.
1275          */
1276         if (qp->r_ack_state != OP(ACKNOWLEDGE) &&
1277             (ipath_cmp24(psn, qp->r_ack_psn) <= 0 ||
1278              qp->r_ack_state >= OP(COMPARE_SWAP)))
1279                 goto send_ack;
1280         switch (opcode) {
1281         case OP(COMPARE_SWAP):
1282         case OP(FETCH_ADD):
1283                 /*
1284                  * Check for the PSN of the last atomic operation
1285                  * performed and resend the result if found.
1286                  */
1287                 if ((psn & IPATH_PSN_MASK) != qp->r_atomic_psn)
1288                         goto done;
1289                 break;
1290         }
1291         qp->r_ack_state = opcode;
1292         qp->r_nak_state = 0;
1293         qp->r_ack_psn = psn;
1294 send_ack:
1295         return 0;
1296
1297 done:
1298         return 1;
1299 }
1300
1301 static void ipath_rc_error(struct ipath_qp *qp, enum ib_wc_status err)
1302 {
1303         spin_lock_irq(&qp->s_lock);
1304         qp->state = IB_QPS_ERR;
1305         ipath_error_qp(qp, err);
1306         spin_unlock_irq(&qp->s_lock);
1307 }
1308
1309 /**
1310  * ipath_rc_rcv - process an incoming RC packet
1311  * @dev: the device this packet came in on
1312  * @hdr: the header of this packet
1313  * @has_grh: true if the header has a GRH
1314  * @data: the packet data
1315  * @tlen: the packet length
1316  * @qp: the QP for this packet
1317  *
1318  * This is called from ipath_qp_rcv() to process an incoming RC packet
1319  * for the given QP.
1320  * Called at interrupt level.
1321  */
1322 void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
1323                   int has_grh, void *data, u32 tlen, struct ipath_qp *qp)
1324 {
1325         struct ipath_other_headers *ohdr;
1326         u32 opcode;
1327         u32 hdrsize;
1328         u32 psn;
1329         u32 pad;
1330         struct ib_wc wc;
1331         u32 pmtu = ib_mtu_enum_to_int(qp->path_mtu);
1332         int diff;
1333         struct ib_reth *reth;
1334         int header_in_data;
1335
1336         /* Validate the SLID. See Ch. 9.6.1.5 */
1337         if (unlikely(be16_to_cpu(hdr->lrh[3]) != qp->remote_ah_attr.dlid))
1338                 goto done;
1339
1340         /* Check for GRH */
1341         if (!has_grh) {
1342                 ohdr = &hdr->u.oth;
1343                 hdrsize = 8 + 12;       /* LRH + BTH */
1344                 psn = be32_to_cpu(ohdr->bth[2]);
1345                 header_in_data = 0;
1346         } else {
1347                 ohdr = &hdr->u.l.oth;
1348                 hdrsize = 8 + 40 + 12;  /* LRH + GRH + BTH */
1349                 /*
1350                  * The header with GRH is 60 bytes and the core driver sets
1351                  * the eager header buffer size to 56 bytes so the last 4
1352                  * bytes of the BTH header (PSN) is in the data buffer.
1353                  */
1354                 header_in_data = dev->dd->ipath_rcvhdrentsize == 16;
1355                 if (header_in_data) {
1356                         psn = be32_to_cpu(((__be32 *) data)[0]);
1357                         data += sizeof(__be32);
1358                 } else
1359                         psn = be32_to_cpu(ohdr->bth[2]);
1360         }
1361
1362         /*
1363          * Process responses (ACKs) before anything else.  Note that the
1364          * packet sequence number will be for something in the send work
1365          * queue rather than the expected receive packet sequence number.
1366          * In other words, this QP is the requester.
1367          */
1368         opcode = be32_to_cpu(ohdr->bth[0]) >> 24;
1369         if (opcode >= OP(RDMA_READ_RESPONSE_FIRST) &&
1370             opcode <= OP(ATOMIC_ACKNOWLEDGE)) {
1371                 ipath_rc_rcv_resp(dev, ohdr, data, tlen, qp, opcode, psn,
1372                                   hdrsize, pmtu, header_in_data);
1373                 goto done;
1374         }
1375
1376         /* Compute 24 bits worth of difference. */
1377         diff = ipath_cmp24(psn, qp->r_psn);
1378         if (unlikely(diff)) {
1379                 if (ipath_rc_rcv_error(dev, ohdr, data, qp, opcode,
1380                                        psn, diff, header_in_data))
1381                         goto done;
1382                 goto send_ack;
1383         }
1384
1385         /* Check for opcode sequence errors. */
1386         switch (qp->r_state) {
1387         case OP(SEND_FIRST):
1388         case OP(SEND_MIDDLE):
1389                 if (opcode == OP(SEND_MIDDLE) ||
1390                     opcode == OP(SEND_LAST) ||
1391                     opcode == OP(SEND_LAST_WITH_IMMEDIATE))
1392                         break;
1393         nack_inv:
1394                 /*
1395                  * A NAK will ACK earlier sends and RDMA writes.
1396                  * Don't queue the NAK if a RDMA read, atomic, or NAK
1397                  * is pending though.
1398                  */
1399                 if (qp->r_ack_state >= OP(COMPARE_SWAP))
1400                         goto send_ack;
1401                 ipath_rc_error(qp, IB_WC_REM_INV_REQ_ERR);
1402                 qp->r_ack_state = OP(SEND_ONLY);
1403                 qp->r_nak_state = IB_NAK_INVALID_REQUEST;
1404                 qp->r_ack_psn = qp->r_psn;
1405                 goto send_ack;
1406
1407         case OP(RDMA_WRITE_FIRST):
1408         case OP(RDMA_WRITE_MIDDLE):
1409                 if (opcode == OP(RDMA_WRITE_MIDDLE) ||
1410                     opcode == OP(RDMA_WRITE_LAST) ||
1411                     opcode == OP(RDMA_WRITE_LAST_WITH_IMMEDIATE))
1412                         break;
1413                 goto nack_inv;
1414
1415         default:
1416                 if (opcode == OP(SEND_MIDDLE) ||
1417                     opcode == OP(SEND_LAST) ||
1418                     opcode == OP(SEND_LAST_WITH_IMMEDIATE) ||
1419                     opcode == OP(RDMA_WRITE_MIDDLE) ||
1420                     opcode == OP(RDMA_WRITE_LAST) ||
1421                     opcode == OP(RDMA_WRITE_LAST_WITH_IMMEDIATE))
1422                         goto nack_inv;
1423                 /*
1424                  * Note that it is up to the requester to not send a new
1425                  * RDMA read or atomic operation before receiving an ACK
1426                  * for the previous operation.
1427                  */
1428                 break;
1429         }
1430
1431         wc.imm_data = 0;
1432         wc.wc_flags = 0;
1433
1434         /* OK, process the packet. */
1435         switch (opcode) {
1436         case OP(SEND_FIRST):
1437                 if (!ipath_get_rwqe(qp, 0)) {
1438                 rnr_nak:
1439                         /*
1440                          * A RNR NAK will ACK earlier sends and RDMA writes.
1441                          * Don't queue the NAK if a RDMA read or atomic
1442                          * is pending though.
1443                          */
1444                         if (qp->r_ack_state >= OP(COMPARE_SWAP))
1445                                 goto send_ack;
1446                         qp->r_ack_state = OP(SEND_ONLY);
1447                         qp->r_nak_state = IB_RNR_NAK | qp->r_min_rnr_timer;
1448                         qp->r_ack_psn = qp->r_psn;
1449                         goto send_ack;
1450                 }
1451                 qp->r_rcv_len = 0;
1452                 /* FALLTHROUGH */
1453         case OP(SEND_MIDDLE):
1454         case OP(RDMA_WRITE_MIDDLE):
1455         send_middle:
1456                 /* Check for invalid length PMTU or posted rwqe len. */
1457                 if (unlikely(tlen != (hdrsize + pmtu + 4)))
1458                         goto nack_inv;
1459                 qp->r_rcv_len += pmtu;
1460                 if (unlikely(qp->r_rcv_len > qp->r_len))
1461                         goto nack_inv;
1462                 ipath_copy_sge(&qp->r_sge, data, pmtu);
1463                 break;
1464
1465         case OP(RDMA_WRITE_LAST_WITH_IMMEDIATE):
1466                 /* consume RWQE */
1467                 if (!ipath_get_rwqe(qp, 1))
1468                         goto rnr_nak;
1469                 goto send_last_imm;
1470
1471         case OP(SEND_ONLY):
1472         case OP(SEND_ONLY_WITH_IMMEDIATE):
1473                 if (!ipath_get_rwqe(qp, 0))
1474                         goto rnr_nak;
1475                 qp->r_rcv_len = 0;
1476                 if (opcode == OP(SEND_ONLY))
1477                         goto send_last;
1478                 /* FALLTHROUGH */
1479         case OP(SEND_LAST_WITH_IMMEDIATE):
1480         send_last_imm:
1481                 if (header_in_data) {
1482                         wc.imm_data = *(__be32 *) data;
1483                         data += sizeof(__be32);
1484                 } else {
1485                         /* Immediate data comes after BTH */
1486                         wc.imm_data = ohdr->u.imm_data;
1487                 }
1488                 hdrsize += 4;
1489                 wc.wc_flags = IB_WC_WITH_IMM;
1490                 /* FALLTHROUGH */
1491         case OP(SEND_LAST):
1492         case OP(RDMA_WRITE_LAST):
1493         send_last:
1494                 /* Get the number of bytes the message was padded by. */
1495                 pad = (be32_to_cpu(ohdr->bth[0]) >> 20) & 3;
1496                 /* Check for invalid length. */
1497                 /* XXX LAST len should be >= 1 */
1498                 if (unlikely(tlen < (hdrsize + pad + 4)))
1499                         goto nack_inv;
1500                 /* Don't count the CRC. */
1501                 tlen -= (hdrsize + pad + 4);
1502                 wc.byte_len = tlen + qp->r_rcv_len;
1503                 if (unlikely(wc.byte_len > qp->r_len))
1504                         goto nack_inv;
1505                 ipath_copy_sge(&qp->r_sge, data, tlen);
1506                 qp->r_msn++;
1507                 if (!qp->r_wrid_valid)
1508                         break;
1509                 qp->r_wrid_valid = 0;
1510                 wc.wr_id = qp->r_wr_id;
1511                 wc.status = IB_WC_SUCCESS;
1512                 wc.opcode = IB_WC_RECV;
1513                 wc.vendor_err = 0;
1514                 wc.qp_num = qp->ibqp.qp_num;
1515                 wc.src_qp = qp->remote_qpn;
1516                 wc.pkey_index = 0;
1517                 wc.slid = qp->remote_ah_attr.dlid;
1518                 wc.sl = qp->remote_ah_attr.sl;
1519                 wc.dlid_path_bits = 0;
1520                 wc.port_num = 0;
1521                 /* Signal completion event if the solicited bit is set. */
1522                 ipath_cq_enter(to_icq(qp->ibqp.recv_cq), &wc,
1523                                (ohdr->bth[0] &
1524                                 __constant_cpu_to_be32(1 << 23)) != 0);
1525                 break;
1526
1527         case OP(RDMA_WRITE_FIRST):
1528         case OP(RDMA_WRITE_ONLY):
1529         case OP(RDMA_WRITE_ONLY_WITH_IMMEDIATE):
1530                 /* consume RWQE */
1531                 /* RETH comes after BTH */
1532                 if (!header_in_data)
1533                         reth = &ohdr->u.rc.reth;
1534                 else {
1535                         reth = (struct ib_reth *)data;
1536                         data += sizeof(*reth);
1537                 }
1538                 hdrsize += sizeof(*reth);
1539                 qp->r_len = be32_to_cpu(reth->length);
1540                 qp->r_rcv_len = 0;
1541                 if (qp->r_len != 0) {
1542                         u32 rkey = be32_to_cpu(reth->rkey);
1543                         u64 vaddr = be64_to_cpu(reth->vaddr);
1544                         int ok;
1545
1546                         /* Check rkey & NAK */
1547                         ok = ipath_rkey_ok(qp, &qp->r_sge,
1548                                            qp->r_len, vaddr, rkey,
1549                                            IB_ACCESS_REMOTE_WRITE);
1550                         if (unlikely(!ok))
1551                                 goto nack_acc;
1552                 } else {
1553                         qp->r_sge.sg_list = NULL;
1554                         qp->r_sge.sge.mr = NULL;
1555                         qp->r_sge.sge.vaddr = NULL;
1556                         qp->r_sge.sge.length = 0;
1557                         qp->r_sge.sge.sge_length = 0;
1558                 }
1559                 if (unlikely(!(qp->qp_access_flags &
1560                                IB_ACCESS_REMOTE_WRITE)))
1561                         goto nack_acc;
1562                 if (opcode == OP(RDMA_WRITE_FIRST))
1563                         goto send_middle;
1564                 else if (opcode == OP(RDMA_WRITE_ONLY))
1565                         goto send_last;
1566                 if (!ipath_get_rwqe(qp, 1))
1567                         goto rnr_nak;
1568                 goto send_last_imm;
1569
1570         case OP(RDMA_READ_REQUEST):
1571                 /* RETH comes after BTH */
1572                 if (!header_in_data)
1573                         reth = &ohdr->u.rc.reth;
1574                 else {
1575                         reth = (struct ib_reth *)data;
1576                         data += sizeof(*reth);
1577                 }
1578                 if (unlikely(!(qp->qp_access_flags &
1579                                IB_ACCESS_REMOTE_READ)))
1580                         goto nack_acc;
1581                 spin_lock_irq(&qp->s_lock);
1582                 qp->s_rdma_len = be32_to_cpu(reth->length);
1583                 if (qp->s_rdma_len != 0) {
1584                         u32 rkey = be32_to_cpu(reth->rkey);
1585                         u64 vaddr = be64_to_cpu(reth->vaddr);
1586                         int ok;
1587
1588                         /* Check rkey & NAK */
1589                         ok = ipath_rkey_ok(qp, &qp->s_rdma_sge,
1590                                            qp->s_rdma_len, vaddr, rkey,
1591                                            IB_ACCESS_REMOTE_READ);
1592                         if (unlikely(!ok)) {
1593                                 spin_unlock_irq(&qp->s_lock);
1594                                 goto nack_acc;
1595                         }
1596                         /*
1597                          * Update the next expected PSN.  We add 1 later
1598                          * below, so only add the remainder here.
1599                          */
1600                         if (qp->s_rdma_len > pmtu)
1601                                 qp->r_psn += (qp->s_rdma_len - 1) / pmtu;
1602                 } else {
1603                         qp->s_rdma_sge.sg_list = NULL;
1604                         qp->s_rdma_sge.num_sge = 0;
1605                         qp->s_rdma_sge.sge.mr = NULL;
1606                         qp->s_rdma_sge.sge.vaddr = NULL;
1607                         qp->s_rdma_sge.sge.length = 0;
1608                         qp->s_rdma_sge.sge.sge_length = 0;
1609                 }
1610                 /*
1611                  * We need to increment the MSN here instead of when we
1612                  * finish sending the result since a duplicate request would
1613                  * increment it more than once.
1614                  */
1615                 qp->r_msn++;
1616
1617                 qp->s_ack_state = opcode;
1618                 qp->s_ack_psn = psn;
1619                 spin_unlock_irq(&qp->s_lock);
1620
1621                 qp->r_psn++;
1622                 qp->r_state = opcode;
1623                 qp->r_nak_state = 0;
1624
1625                 /* Call ipath_do_rc_send() in another thread. */
1626                 tasklet_hi_schedule(&qp->s_task);
1627
1628                 goto done;
1629
1630         case OP(COMPARE_SWAP):
1631         case OP(FETCH_ADD): {
1632                 struct ib_atomic_eth *ateth;
1633                 u64 vaddr;
1634                 u64 sdata;
1635                 u32 rkey;
1636
1637                 if (!header_in_data)
1638                         ateth = &ohdr->u.atomic_eth;
1639                 else {
1640                         ateth = (struct ib_atomic_eth *)data;
1641                         data += sizeof(*ateth);
1642                 }
1643                 vaddr = be64_to_cpu(ateth->vaddr);
1644                 if (unlikely(vaddr & (sizeof(u64) - 1)))
1645                         goto nack_inv;
1646                 rkey = be32_to_cpu(ateth->rkey);
1647                 /* Check rkey & NAK */
1648                 if (unlikely(!ipath_rkey_ok(qp, &qp->r_sge,
1649                                             sizeof(u64), vaddr, rkey,
1650                                             IB_ACCESS_REMOTE_ATOMIC)))
1651                         goto nack_acc;
1652                 if (unlikely(!(qp->qp_access_flags &
1653                                IB_ACCESS_REMOTE_ATOMIC)))
1654                         goto nack_acc;
1655                 /* Perform atomic OP and save result. */
1656                 sdata = be64_to_cpu(ateth->swap_data);
1657                 spin_lock_irq(&dev->pending_lock);
1658                 qp->r_atomic_data = *(u64 *) qp->r_sge.sge.vaddr;
1659                 if (opcode == OP(FETCH_ADD))
1660                         *(u64 *) qp->r_sge.sge.vaddr =
1661                                 qp->r_atomic_data + sdata;
1662                 else if (qp->r_atomic_data ==
1663                          be64_to_cpu(ateth->compare_data))
1664                         *(u64 *) qp->r_sge.sge.vaddr = sdata;
1665                 spin_unlock_irq(&dev->pending_lock);
1666                 qp->r_msn++;
1667                 qp->r_atomic_psn = psn & IPATH_PSN_MASK;
1668                 psn |= 1 << 31;
1669                 break;
1670         }
1671
1672         default:
1673                 /* Drop packet for unknown opcodes. */
1674                 goto done;
1675         }
1676         qp->r_psn++;
1677         qp->r_state = opcode;
1678         qp->r_nak_state = 0;
1679         /* Send an ACK if requested or required. */
1680         if (psn & (1 << 31)) {
1681                 /*
1682                  * Coalesce ACKs unless there is a RDMA READ or
1683                  * ATOMIC pending.
1684                  */
1685                 if (qp->r_ack_state < OP(COMPARE_SWAP)) {
1686                         qp->r_ack_state = opcode;
1687                         qp->r_ack_psn = psn;
1688                 }
1689                 goto send_ack;
1690         }
1691         goto done;
1692
1693 nack_acc:
1694         /*
1695          * A NAK will ACK earlier sends and RDMA writes.
1696          * Don't queue the NAK if a RDMA read, atomic, or NAK
1697          * is pending though.
1698          */
1699         if (qp->r_ack_state < OP(COMPARE_SWAP)) {
1700                 ipath_rc_error(qp, IB_WC_REM_ACCESS_ERR);
1701                 qp->r_ack_state = OP(RDMA_WRITE_ONLY);
1702                 qp->r_nak_state = IB_NAK_REMOTE_ACCESS_ERROR;
1703                 qp->r_ack_psn = qp->r_psn;
1704         }
1705 send_ack:
1706         /* Send ACK right away unless the send tasklet has a pending ACK. */
1707         if (qp->s_ack_state == OP(ACKNOWLEDGE))
1708                 send_rc_ack(qp);
1709
1710 done:
1711         return;
1712 }