drivers/infiniband/sw/rxe/rxe_comp.c

   1 /*
   2  * Copyright (c) 2016 Mellanox Technologies Ltd. All rights reserved.
   3  * Copyright (c) 2015 System Fabric Works, 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 <linux/skbuff.h>
  35
  36 #include "rxe.h"
  37 #include "rxe_loc.h"
  38 #include "rxe_queue.h"
  39 #include "rxe_task.h"
  40
  41 enum comp_state {
  42         COMPST_GET_ACK,
  43         COMPST_GET_WQE,
  44         COMPST_COMP_WQE,
  45         COMPST_COMP_ACK,
  46         COMPST_CHECK_PSN,
  47         COMPST_CHECK_ACK,
  48         COMPST_READ,
  49         COMPST_ATOMIC,
  50         COMPST_WRITE_SEND,
  51         COMPST_UPDATE_COMP,
  52         COMPST_ERROR_RETRY,
  53         COMPST_RNR_RETRY,
  54         COMPST_ERROR,
  55         COMPST_EXIT, /* We have an issue, and we want to rerun the completer */
  56         COMPST_DONE, /* The completer finished successflly */
  57 };
  58
  59 static char *comp_state_name[] =  {
  60         [COMPST_GET_ACK]                = "GET ACK",
  61         [COMPST_GET_WQE]                = "GET WQE",
  62         [COMPST_COMP_WQE]               = "COMP WQE",
  63         [COMPST_COMP_ACK]               = "COMP ACK",
  64         [COMPST_CHECK_PSN]              = "CHECK PSN",
  65         [COMPST_CHECK_ACK]              = "CHECK ACK",
  66         [COMPST_READ]                   = "READ",
  67         [COMPST_ATOMIC]                 = "ATOMIC",
  68         [COMPST_WRITE_SEND]             = "WRITE/SEND",
  69         [COMPST_UPDATE_COMP]            = "UPDATE COMP",
  70         [COMPST_ERROR_RETRY]            = "ERROR RETRY",
  71         [COMPST_RNR_RETRY]              = "RNR RETRY",
  72         [COMPST_ERROR]                  = "ERROR",
  73         [COMPST_EXIT]                   = "EXIT",
  74         [COMPST_DONE]                   = "DONE",
  75 };
  76
  77 static unsigned long rnrnak_usec[32] = {
  78         [IB_RNR_TIMER_655_36] = 655360,
  79         [IB_RNR_TIMER_000_01] = 10,
  80         [IB_RNR_TIMER_000_02] = 20,
  81         [IB_RNR_TIMER_000_03] = 30,
  82         [IB_RNR_TIMER_000_04] = 40,
  83         [IB_RNR_TIMER_000_06] = 60,
  84         [IB_RNR_TIMER_000_08] = 80,
  85         [IB_RNR_TIMER_000_12] = 120,
  86         [IB_RNR_TIMER_000_16] = 160,
  87         [IB_RNR_TIMER_000_24] = 240,
  88         [IB_RNR_TIMER_000_32] = 320,
  89         [IB_RNR_TIMER_000_48] = 480,
  90         [IB_RNR_TIMER_000_64] = 640,
  91         [IB_RNR_TIMER_000_96] = 960,
  92         [IB_RNR_TIMER_001_28] = 1280,
  93         [IB_RNR_TIMER_001_92] = 1920,
  94         [IB_RNR_TIMER_002_56] = 2560,
  95         [IB_RNR_TIMER_003_84] = 3840,
  96         [IB_RNR_TIMER_005_12] = 5120,
  97         [IB_RNR_TIMER_007_68] = 7680,
  98         [IB_RNR_TIMER_010_24] = 10240,
  99         [IB_RNR_TIMER_015_36] = 15360,
 100         [IB_RNR_TIMER_020_48] = 20480,
 101         [IB_RNR_TIMER_030_72] = 30720,
 102         [IB_RNR_TIMER_040_96] = 40960,
 103         [IB_RNR_TIMER_061_44] = 61410,
 104         [IB_RNR_TIMER_081_92] = 81920,
 105         [IB_RNR_TIMER_122_88] = 122880,
 106         [IB_RNR_TIMER_163_84] = 163840,
 107         [IB_RNR_TIMER_245_76] = 245760,
 108         [IB_RNR_TIMER_327_68] = 327680,
 109         [IB_RNR_TIMER_491_52] = 491520,
 110 };
 111
 112 static inline unsigned long rnrnak_jiffies(u8 timeout)
 113 {
 114         return max_t(unsigned long,
 115                 usecs_to_jiffies(rnrnak_usec[timeout]), 1);
 116 }
 117
 118 static enum ib_wc_opcode wr_to_wc_opcode(enum ib_wr_opcode opcode)
 119 {
 120         switch (opcode) {
 121         case IB_WR_RDMA_WRITE:                  return IB_WC_RDMA_WRITE;
 122         case IB_WR_RDMA_WRITE_WITH_IMM:         return IB_WC_RDMA_WRITE;
 123         case IB_WR_SEND:                        return IB_WC_SEND;
 124         case IB_WR_SEND_WITH_IMM:               return IB_WC_SEND;
 125         case IB_WR_RDMA_READ:                   return IB_WC_RDMA_READ;
 126         case IB_WR_ATOMIC_CMP_AND_SWP:          return IB_WC_COMP_SWAP;
 127         case IB_WR_ATOMIC_FETCH_AND_ADD:        return IB_WC_FETCH_ADD;
 128         case IB_WR_LSO:                         return IB_WC_LSO;
 129         case IB_WR_SEND_WITH_INV:               return IB_WC_SEND;
 130         case IB_WR_RDMA_READ_WITH_INV:          return IB_WC_RDMA_READ;
 131         case IB_WR_LOCAL_INV:                   return IB_WC_LOCAL_INV;
 132         case IB_WR_REG_MR:                      return IB_WC_REG_MR;
 133
 134         default:
 135                 return 0xff;
 136         }
 137 }
 138
 139 void retransmit_timer(unsigned long data)
 140 {
 141         struct rxe_qp *qp = (struct rxe_qp *)data;
 142
 143         if (qp->valid) {
 144                 qp->comp.timeout = 1;
 145                 rxe_run_task(&qp->comp.task, 1);
 146         }
 147 }
 148
 149 void rxe_comp_queue_pkt(struct rxe_dev *rxe, struct rxe_qp *qp,
 150                         struct sk_buff *skb)
 151 {
 152         int must_sched;
 153
 154         skb_queue_tail(&qp->resp_pkts, skb);
 155
 156         must_sched = skb_queue_len(&qp->resp_pkts) > 1;
 157         rxe_run_task(&qp->comp.task, must_sched);
 158 }
 159
 160 static inline enum comp_state get_wqe(struct rxe_qp *qp,
 161                                       struct rxe_pkt_info *pkt,
 162                                       struct rxe_send_wqe **wqe_p)
 163 {
 164         struct rxe_send_wqe *wqe;
 165
 166         /* we come here whether or not we found a response packet to see if
 167          * there are any posted WQEs
 168          */
 169         wqe = queue_head(qp->sq.queue);
 170         *wqe_p = wqe;
 171
 172         /* no WQE or requester has not started it yet */
 173         if (!wqe || wqe->state == wqe_state_posted)
 174                 return pkt ? COMPST_DONE : COMPST_EXIT;
 175
 176         /* WQE does not require an ack */
 177         if (wqe->state == wqe_state_done)
 178                 return COMPST_COMP_WQE;
 179
 180         /* WQE caused an error */
 181         if (wqe->state == wqe_state_error)
 182                 return COMPST_ERROR;
 183
 184         /* we have a WQE, if we also have an ack check its PSN */
 185         return pkt ? COMPST_CHECK_PSN : COMPST_EXIT;
 186 }
 187
 188 static inline void reset_retry_counters(struct rxe_qp *qp)
 189 {
 190         qp->comp.retry_cnt = qp->attr.retry_cnt;
 191         qp->comp.rnr_retry = qp->attr.rnr_retry;
 192 }
 193
 194 static inline enum comp_state check_psn(struct rxe_qp *qp,
 195                                         struct rxe_pkt_info *pkt,
 196                                         struct rxe_send_wqe *wqe)
 197 {
 198         s32 diff;
 199
 200         /* check to see if response is past the oldest WQE. if it is, complete
 201          * send/write or error read/atomic
 202          */
 203         diff = psn_compare(pkt->psn, wqe->last_psn);
 204         if (diff > 0) {
 205                 if (wqe->state == wqe_state_pending) {
 206                         if (wqe->mask & WR_ATOMIC_OR_READ_MASK)
 207                                 return COMPST_ERROR_RETRY;
 208
 209                         reset_retry_counters(qp);
 210                         return COMPST_COMP_WQE;
 211                 } else {
 212                         return COMPST_DONE;
 213                 }
 214         }
 215
 216         /* compare response packet to expected response */
 217         diff = psn_compare(pkt->psn, qp->comp.psn);
 218         if (diff < 0) {
 219                 /* response is most likely a retried packet if it matches an
 220                  * uncompleted WQE go complete it else ignore it
 221                  */
 222                 if (pkt->psn == wqe->last_psn)
 223                         return COMPST_COMP_ACK;
 224                 else
 225                         return COMPST_DONE;
 226         } else if ((diff > 0) && (wqe->mask & WR_ATOMIC_OR_READ_MASK)) {
 227                 return COMPST_ERROR_RETRY;
 228         } else {
 229                 return COMPST_CHECK_ACK;
 230         }
 231 }
 232
 233 static inline enum comp_state check_ack(struct rxe_qp *qp,
 234                                         struct rxe_pkt_info *pkt,
 235                                         struct rxe_send_wqe *wqe)
 236 {
 237         unsigned int mask = pkt->mask;
 238         u8 syn;
 239
 240         /* Check the sequence only */
 241         switch (qp->comp.opcode) {
 242         case -1:
 243                 /* Will catch all *_ONLY cases. */
 244                 if (!(mask & RXE_START_MASK))
 245                         return COMPST_ERROR;
 246
 247                 break;
 248
 249         case IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST:
 250         case IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE:
 251                 if (pkt->opcode != IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE &&
 252                     pkt->opcode != IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST) {
 253                         /* read retries of partial data may restart from
 254                          * read response first or response only.
 255                          */
 256                         if ((pkt->psn == wqe->first_psn &&
 257                              pkt->opcode ==
 258                              IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST) ||
 259                             (wqe->first_psn == wqe->last_psn &&
 260                              pkt->opcode ==
 261                              IB_OPCODE_RC_RDMA_READ_RESPONSE_ONLY))
 262                                 break;
 263
 264                         return COMPST_ERROR;
 265                 }
 266                 break;
 267         default:
 268                 WARN_ON(1);
 269         }
 270
 271         /* Check operation validity. */
 272         switch (pkt->opcode) {
 273         case IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST:
 274         case IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST:
 275         case IB_OPCODE_RC_RDMA_READ_RESPONSE_ONLY:
 276                 syn = aeth_syn(pkt);
 277
 278                 if ((syn & AETH_TYPE_MASK) != AETH_ACK)
 279                         return COMPST_ERROR;
 280
 281                 /* Fall through (IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE
 282                  * doesn't have an AETH)
 283                  */
 284         case IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE:
 285                 if (wqe->wr.opcode != IB_WR_RDMA_READ &&
 286                     wqe->wr.opcode != IB_WR_RDMA_READ_WITH_INV) {
 287                         wqe->status = IB_WC_FATAL_ERR;
 288                         return COMPST_ERROR;
 289                 }
 290                 reset_retry_counters(qp);
 291                 return COMPST_READ;
 292
 293         case IB_OPCODE_RC_ATOMIC_ACKNOWLEDGE:
 294                 syn = aeth_syn(pkt);
 295
 296                 if ((syn & AETH_TYPE_MASK) != AETH_ACK)
 297                         return COMPST_ERROR;
 298
 299                 if (wqe->wr.opcode != IB_WR_ATOMIC_CMP_AND_SWP &&
 300                     wqe->wr.opcode != IB_WR_ATOMIC_FETCH_AND_ADD)
 301                         return COMPST_ERROR;
 302                 reset_retry_counters(qp);
 303                 return COMPST_ATOMIC;
 304
 305         case IB_OPCODE_RC_ACKNOWLEDGE:
 306                 syn = aeth_syn(pkt);
 307                 switch (syn & AETH_TYPE_MASK) {
 308                 case AETH_ACK:
 309                         reset_retry_counters(qp);
 310                         return COMPST_WRITE_SEND;
 311
 312                 case AETH_RNR_NAK:
 313                         return COMPST_RNR_RETRY;
 314
 315                 case AETH_NAK:
 316                         switch (syn) {
 317                         case AETH_NAK_PSN_SEQ_ERROR:
 318                                 /* a nak implicitly acks all packets with psns
 319                                  * before
 320                                  */
 321                                 if (psn_compare(pkt->psn, qp->comp.psn) > 0) {
 322                                         qp->comp.psn = pkt->psn;
 323                                         if (qp->req.wait_psn) {
 324                                                 qp->req.wait_psn = 0;
 325                                                 rxe_run_task(&qp->req.task, 1);
 326                                         }
 327                                 }
 328                                 return COMPST_ERROR_RETRY;
 329
 330                         case AETH_NAK_INVALID_REQ:
 331                                 wqe->status = IB_WC_REM_INV_REQ_ERR;
 332                                 return COMPST_ERROR;
 333
 334                         case AETH_NAK_REM_ACC_ERR:
 335                                 wqe->status = IB_WC_REM_ACCESS_ERR;
 336                                 return COMPST_ERROR;
 337
 338                         case AETH_NAK_REM_OP_ERR:
 339                                 wqe->status = IB_WC_REM_OP_ERR;
 340                                 return COMPST_ERROR;
 341
 342                         default:
 343                                 pr_warn("unexpected nak %x\n", syn);
 344                                 wqe->status = IB_WC_REM_OP_ERR;
 345                                 return COMPST_ERROR;
 346                         }
 347
 348                 default:
 349                         return COMPST_ERROR;
 350                 }
 351                 break;
 352
 353         default:
 354                 pr_warn("unexpected opcode\n");
 355         }
 356
 357         return COMPST_ERROR;
 358 }
 359
 360 static inline enum comp_state do_read(struct rxe_qp *qp,
 361                                       struct rxe_pkt_info *pkt,
 362                                       struct rxe_send_wqe *wqe)
 363 {
 364         struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
 365         int ret;
 366
 367         ret = copy_data(rxe, qp->pd, IB_ACCESS_LOCAL_WRITE,
 368                         &wqe->dma, payload_addr(pkt),
 369                         payload_size(pkt), to_mem_obj, NULL);
 370         if (ret)
 371                 return COMPST_ERROR;
 372
 373         if (wqe->dma.resid == 0 && (pkt->mask & RXE_END_MASK))
 374                 return COMPST_COMP_ACK;
 375         else
 376                 return COMPST_UPDATE_COMP;
 377 }
 378
 379 static inline enum comp_state do_atomic(struct rxe_qp *qp,
 380                                         struct rxe_pkt_info *pkt,
 381                                         struct rxe_send_wqe *wqe)
 382 {
 383         struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
 384         int ret;
 385
 386         u64 atomic_orig = atmack_orig(pkt);
 387
 388         ret = copy_data(rxe, qp->pd, IB_ACCESS_LOCAL_WRITE,
 389                         &wqe->dma, &atomic_orig,
 390                         sizeof(u64), to_mem_obj, NULL);
 391         if (ret)
 392                 return COMPST_ERROR;
 393         else
 394                 return COMPST_COMP_ACK;
 395 }
 396
 397 static void make_send_cqe(struct rxe_qp *qp, struct rxe_send_wqe *wqe,
 398                           struct rxe_cqe *cqe)
 399 {
 400         memset(cqe, 0, sizeof(*cqe));
 401
 402         if (!qp->is_user) {
 403                 struct ib_wc            *wc     = &cqe->ibwc;
 404
 405                 wc->wr_id               = wqe->wr.wr_id;
 406                 wc->status              = wqe->status;
 407                 wc->opcode              = wr_to_wc_opcode(wqe->wr.opcode);
 408                 if (wqe->wr.opcode == IB_WR_RDMA_WRITE_WITH_IMM ||
 409                     wqe->wr.opcode == IB_WR_SEND_WITH_IMM)
 410                         wc->wc_flags = IB_WC_WITH_IMM;
 411                 wc->byte_len            = wqe->dma.length;
 412                 wc->qp                  = &qp->ibqp;
 413         } else {
 414                 struct ib_uverbs_wc     *uwc    = &cqe->uibwc;
 415
 416                 uwc->wr_id              = wqe->wr.wr_id;
 417                 uwc->status             = wqe->status;
 418                 uwc->opcode             = wr_to_wc_opcode(wqe->wr.opcode);
 419                 if (wqe->wr.opcode == IB_WR_RDMA_WRITE_WITH_IMM ||
 420                     wqe->wr.opcode == IB_WR_SEND_WITH_IMM)
 421                         uwc->wc_flags = IB_WC_WITH_IMM;
 422                 uwc->byte_len           = wqe->dma.length;
 423                 uwc->qp_num             = qp->ibqp.qp_num;
 424         }
 425 }
 426
 427 static void do_complete(struct rxe_qp *qp, struct rxe_send_wqe *wqe)
 428 {
 429         struct rxe_cqe cqe;
 430
 431         if ((qp->sq_sig_type == IB_SIGNAL_ALL_WR) ||
 432             (wqe->wr.send_flags & IB_SEND_SIGNALED) ||
 433             (qp->req.state == QP_STATE_ERROR)) {
 434                 make_send_cqe(qp, wqe, &cqe);
 435                 rxe_cq_post(qp->scq, &cqe, 0);
 436         }
 437
 438         advance_consumer(qp->sq.queue);
 439
 440         /*
 441          * we completed something so let req run again
 442          * if it is trying to fence
 443          */
 444         if (qp->req.wait_fence) {
 445                 qp->req.wait_fence = 0;
 446                 rxe_run_task(&qp->req.task, 1);
 447         }
 448 }
 449
 450 static inline enum comp_state complete_ack(struct rxe_qp *qp,
 451                                            struct rxe_pkt_info *pkt,
 452                                            struct rxe_send_wqe *wqe)
 453 {
 454         unsigned long flags;
 455
 456         if (wqe->has_rd_atomic) {
 457                 wqe->has_rd_atomic = 0;
 458                 atomic_inc(&qp->req.rd_atomic);
 459                 if (qp->req.need_rd_atomic) {
 460                         qp->comp.timeout_retry = 0;
 461                         qp->req.need_rd_atomic = 0;
 462                         rxe_run_task(&qp->req.task, 1);
 463                 }
 464         }
 465
 466         if (unlikely(qp->req.state == QP_STATE_DRAIN)) {
 467                 /* state_lock used by requester & completer */
 468                 spin_lock_irqsave(&qp->state_lock, flags);
 469                 if ((qp->req.state == QP_STATE_DRAIN) &&
 470                     (qp->comp.psn == qp->req.psn)) {
 471                         qp->req.state = QP_STATE_DRAINED;
 472                         spin_unlock_irqrestore(&qp->state_lock, flags);
 473
 474                         if (qp->ibqp.event_handler) {
 475                                 struct ib_event ev;
 476
 477                                 ev.device = qp->ibqp.device;
 478                                 ev.element.qp = &qp->ibqp;
 479                                 ev.event = IB_EVENT_SQ_DRAINED;
 480                                 qp->ibqp.event_handler(&ev,
 481                                         qp->ibqp.qp_context);
 482                         }
 483                 } else {
 484                         spin_unlock_irqrestore(&qp->state_lock, flags);
 485                 }
 486         }
 487
 488         do_complete(qp, wqe);
 489
 490         if (psn_compare(pkt->psn, qp->comp.psn) >= 0)
 491                 return COMPST_UPDATE_COMP;
 492         else
 493                 return COMPST_DONE;
 494 }
 495
 496 static inline enum comp_state complete_wqe(struct rxe_qp *qp,
 497                                            struct rxe_pkt_info *pkt,
 498                                            struct rxe_send_wqe *wqe)
 499 {
 500         if (pkt && wqe->state == wqe_state_pending) {
 501                 if (psn_compare(wqe->last_psn, qp->comp.psn) >= 0) {
 502                         qp->comp.psn = (wqe->last_psn + 1) & BTH_PSN_MASK;
 503                         qp->comp.opcode = -1;
 504                 }
 505
 506                 if (qp->req.wait_psn) {
 507                         qp->req.wait_psn = 0;
 508                         rxe_run_task(&qp->req.task, 1);
 509                 }
 510         }
 511
 512         do_complete(qp, wqe);
 513
 514         return COMPST_GET_WQE;
 515 }
 516
 517 int rxe_completer(void *arg)
 518 {
 519         struct rxe_qp *qp = (struct rxe_qp *)arg;
 520         struct rxe_send_wqe *wqe = wqe;
 521         struct sk_buff *skb = NULL;
 522         struct rxe_pkt_info *pkt = NULL;
 523         enum comp_state state;
 524
 525         if (!qp->valid) {
 526                 while ((skb = skb_dequeue(&qp->resp_pkts))) {
 527                         rxe_drop_ref(qp);
 528                         kfree_skb(skb);
 529                 }
 530                 skb = NULL;
 531                 pkt = NULL;
 532
 533                 while (queue_head(qp->sq.queue))
 534                         advance_consumer(qp->sq.queue);
 535
 536                 goto exit;
 537         }
 538
 539         if (qp->req.state == QP_STATE_ERROR) {
 540                 while ((skb = skb_dequeue(&qp->resp_pkts))) {
 541                         rxe_drop_ref(qp);
 542                         kfree_skb(skb);
 543                 }
 544                 skb = NULL;
 545                 pkt = NULL;
 546
 547                 while ((wqe = queue_head(qp->sq.queue))) {
 548                         wqe->status = IB_WC_WR_FLUSH_ERR;
 549                         do_complete(qp, wqe);
 550                 }
 551
 552                 goto exit;
 553         }
 554
 555         if (qp->req.state == QP_STATE_RESET) {
 556                 while ((skb = skb_dequeue(&qp->resp_pkts))) {
 557                         rxe_drop_ref(qp);
 558                         kfree_skb(skb);
 559                 }
 560                 skb = NULL;
 561                 pkt = NULL;
 562
 563                 while (queue_head(qp->sq.queue))
 564                         advance_consumer(qp->sq.queue);
 565
 566                 goto exit;
 567         }
 568
 569         if (qp->comp.timeout) {
 570                 qp->comp.timeout_retry = 1;
 571                 qp->comp.timeout = 0;
 572         } else {
 573                 qp->comp.timeout_retry = 0;
 574         }
 575
 576         if (qp->req.need_retry)
 577                 goto exit;
 578
 579         state = COMPST_GET_ACK;
 580
 581         while (1) {
 582                 pr_debug("qp#%d state = %s\n", qp_num(qp),
 583                          comp_state_name[state]);
 584                 switch (state) {
 585                 case COMPST_GET_ACK:
 586                         skb = skb_dequeue(&qp->resp_pkts);
 587                         if (skb) {
 588                                 pkt = SKB_TO_PKT(skb);
 589                                 qp->comp.timeout_retry = 0;
 590                         }
 591                         state = COMPST_GET_WQE;
 592                         break;
 593
 594                 case COMPST_GET_WQE:
 595                         state = get_wqe(qp, pkt, &wqe);
 596                         break;
 597
 598                 case COMPST_CHECK_PSN:
 599                         state = check_psn(qp, pkt, wqe);
 600                         break;
 601
 602                 case COMPST_CHECK_ACK:
 603                         state = check_ack(qp, pkt, wqe);
 604                         break;
 605
 606                 case COMPST_READ:
 607                         state = do_read(qp, pkt, wqe);
 608                         break;
 609
 610                 case COMPST_ATOMIC:
 611                         state = do_atomic(qp, pkt, wqe);
 612                         break;
 613
 614                 case COMPST_WRITE_SEND:
 615                         if (wqe->state == wqe_state_pending &&
 616                             wqe->last_psn == pkt->psn)
 617                                 state = COMPST_COMP_ACK;
 618                         else
 619                                 state = COMPST_UPDATE_COMP;
 620                         break;
 621
 622                 case COMPST_COMP_ACK:
 623                         state = complete_ack(qp, pkt, wqe);
 624                         break;
 625
 626                 case COMPST_COMP_WQE:
 627                         state = complete_wqe(qp, pkt, wqe);
 628                         break;
 629
 630                 case COMPST_UPDATE_COMP:
 631                         if (pkt->mask & RXE_END_MASK)
 632                                 qp->comp.opcode = -1;
 633                         else
 634                                 qp->comp.opcode = pkt->opcode;
 635
 636                         if (psn_compare(pkt->psn, qp->comp.psn) >= 0)
 637                                 qp->comp.psn = (pkt->psn + 1) & BTH_PSN_MASK;
 638
 639                         if (qp->req.wait_psn) {
 640                                 qp->req.wait_psn = 0;
 641                                 rxe_run_task(&qp->req.task, 1);
 642                         }
 643
 644                         state = COMPST_DONE;
 645                         break;
 646
 647                 case COMPST_DONE:
 648                         if (pkt) {
 649                                 rxe_drop_ref(pkt->qp);
 650                                 kfree_skb(skb);
 651                         }
 652                         goto done;
 653
 654                 case COMPST_EXIT:
 655                         if (qp->comp.timeout_retry && wqe) {
 656                                 state = COMPST_ERROR_RETRY;
 657                                 break;
 658                         }
 659
 660                         /* re reset the timeout counter if
 661                          * (1) QP is type RC
 662                          * (2) the QP is alive
 663                          * (3) there is a packet sent by the requester that
 664                          *     might be acked (we still might get spurious
 665                          *     timeouts but try to keep them as few as possible)
 666                          * (4) the timeout parameter is set
 667                          */
 668                         if ((qp_type(qp) == IB_QPT_RC) &&
 669                             (qp->req.state == QP_STATE_READY) &&
 670                             (psn_compare(qp->req.psn, qp->comp.psn) > 0) &&
 671                             qp->qp_timeout_jiffies)
 672                                 mod_timer(&qp->retrans_timer,
 673                                           jiffies + qp->qp_timeout_jiffies);
 674                         goto exit;
 675
 676                 case COMPST_ERROR_RETRY:
 677                         /* we come here if the retry timer fired and we did
 678                          * not receive a response packet. try to retry the send
 679                          * queue if that makes sense and the limits have not
 680                          * been exceeded. remember that some timeouts are
 681                          * spurious since we do not reset the timer but kick
 682                          * it down the road or let it expire
 683                          */
 684
 685                         /* there is nothing to retry in this case */
 686                         if (!wqe || (wqe->state == wqe_state_posted))
 687                                 goto exit;
 688
 689                         if (qp->comp.retry_cnt > 0) {
 690                                 if (qp->comp.retry_cnt != 7)
 691                                         qp->comp.retry_cnt--;
 692
 693                                 /* no point in retrying if we have already
 694                                  * seen the last ack that the requester could
 695                                  * have caused
 696                                  */
 697                                 if (psn_compare(qp->req.psn,
 698                                                 qp->comp.psn) > 0) {
 699                                         /* tell the requester to retry the
 700                                          * send send queue next time around
 701                                          */
 702                                         qp->req.need_retry = 1;
 703                                         rxe_run_task(&qp->req.task, 1);
 704                                 }
 705
 706                                 if (pkt) {
 707                                         rxe_drop_ref(pkt->qp);
 708                                         kfree_skb(skb);
 709                                 }
 710
 711                                 goto exit;
 712
 713                         } else {
 714                                 wqe->status = IB_WC_RETRY_EXC_ERR;
 715                                 state = COMPST_ERROR;
 716                         }
 717                         break;
 718
 719                 case COMPST_RNR_RETRY:
 720                         if (qp->comp.rnr_retry > 0) {
 721                                 if (qp->comp.rnr_retry != 7)
 722                                         qp->comp.rnr_retry--;
 723
 724                                 qp->req.need_retry = 1;
 725                                 pr_debug("qp#%d set rnr nak timer\n",
 726                                          qp_num(qp));
 727                                 mod_timer(&qp->rnr_nak_timer,
 728                                           jiffies + rnrnak_jiffies(aeth_syn(pkt)
 729                                                 & ~AETH_TYPE_MASK));
 730                                 goto exit;
 731                         } else {
 732                                 wqe->status = IB_WC_RNR_RETRY_EXC_ERR;
 733                                 state = COMPST_ERROR;
 734                         }
 735                         break;
 736
 737                 case COMPST_ERROR:
 738                         do_complete(qp, wqe);
 739                         rxe_qp_error(qp);
 740
 741                         if (pkt) {
 742                                 rxe_drop_ref(pkt->qp);
 743                                 kfree_skb(skb);
 744                         }
 745
 746                         goto exit;
 747                 }
 748         }
 749
 750 exit:
 751         /* we come here if we are done with processing and want the task to
 752          * exit from the loop calling us
 753          */
 754         return -EAGAIN;
 755
 756 done:
 757         /* we come here if we have processed a packet we want the task to call
 758          * us again to see if there is anything else to do
 759          */
 760         return 0;
 761 }