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_DONE;
 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                         return COMPST_ERROR;
 254                 }
 255                 break;
 256         default:
 257                 WARN_ON(1);
 258         }
 259
 260         /* Check operation validity. */
 261         switch (pkt->opcode) {
 262         case IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST:
 263         case IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST:
 264         case IB_OPCODE_RC_RDMA_READ_RESPONSE_ONLY:
 265                 syn = aeth_syn(pkt);
 266
 267                 if ((syn & AETH_TYPE_MASK) != AETH_ACK)
 268                         return COMPST_ERROR;
 269
 270                 /* Fall through (IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE
 271                  * doesn't have an AETH)
 272                  */
 273         case IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE:
 274                 if (wqe->wr.opcode != IB_WR_RDMA_READ &&
 275                     wqe->wr.opcode != IB_WR_RDMA_READ_WITH_INV) {
 276                         return COMPST_ERROR;
 277                 }
 278                 reset_retry_counters(qp);
 279                 return COMPST_READ;
 280
 281         case IB_OPCODE_RC_ATOMIC_ACKNOWLEDGE:
 282                 syn = aeth_syn(pkt);
 283
 284                 if ((syn & AETH_TYPE_MASK) != AETH_ACK)
 285                         return COMPST_ERROR;
 286
 287                 if (wqe->wr.opcode != IB_WR_ATOMIC_CMP_AND_SWP &&
 288                     wqe->wr.opcode != IB_WR_ATOMIC_FETCH_AND_ADD)
 289                         return COMPST_ERROR;
 290                 reset_retry_counters(qp);
 291                 return COMPST_ATOMIC;
 292
 293         case IB_OPCODE_RC_ACKNOWLEDGE:
 294                 syn = aeth_syn(pkt);
 295                 switch (syn & AETH_TYPE_MASK) {
 296                 case AETH_ACK:
 297                         reset_retry_counters(qp);
 298                         return COMPST_WRITE_SEND;
 299
 300                 case AETH_RNR_NAK:
 301                         return COMPST_RNR_RETRY;
 302
 303                 case AETH_NAK:
 304                         switch (syn) {
 305                         case AETH_NAK_PSN_SEQ_ERROR:
 306                                 /* a nak implicitly acks all packets with psns
 307                                  * before
 308                                  */
 309                                 if (psn_compare(pkt->psn, qp->comp.psn) > 0) {
 310                                         qp->comp.psn = pkt->psn;
 311                                         if (qp->req.wait_psn) {
 312                                                 qp->req.wait_psn = 0;
 313                                                 rxe_run_task(&qp->req.task, 1);
 314                                         }
 315                                 }
 316                                 return COMPST_ERROR_RETRY;
 317
 318                         case AETH_NAK_INVALID_REQ:
 319                                 wqe->status = IB_WC_REM_INV_REQ_ERR;
 320                                 return COMPST_ERROR;
 321
 322                         case AETH_NAK_REM_ACC_ERR:
 323                                 wqe->status = IB_WC_REM_ACCESS_ERR;
 324                                 return COMPST_ERROR;
 325
 326                         case AETH_NAK_REM_OP_ERR:
 327                                 wqe->status = IB_WC_REM_OP_ERR;
 328                                 return COMPST_ERROR;
 329
 330                         default:
 331                                 pr_warn("unexpected nak %x\n", syn);
 332                                 wqe->status = IB_WC_REM_OP_ERR;
 333                                 return COMPST_ERROR;
 334                         }
 335
 336                 default:
 337                         return COMPST_ERROR;
 338                 }
 339                 break;
 340
 341         default:
 342                 pr_warn("unexpected opcode\n");
 343         }
 344
 345         return COMPST_ERROR;
 346 }
 347
 348 static inline enum comp_state do_read(struct rxe_qp *qp,
 349                                       struct rxe_pkt_info *pkt,
 350                                       struct rxe_send_wqe *wqe)
 351 {
 352         struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
 353         int ret;
 354
 355         ret = copy_data(rxe, qp->pd, IB_ACCESS_LOCAL_WRITE,
 356                         &wqe->dma, payload_addr(pkt),
 357                         payload_size(pkt), to_mem_obj, NULL);
 358         if (ret)
 359                 return COMPST_ERROR;
 360
 361         if (wqe->dma.resid == 0 && (pkt->mask & RXE_END_MASK))
 362                 return COMPST_COMP_ACK;
 363         else
 364                 return COMPST_UPDATE_COMP;
 365 }
 366
 367 static inline enum comp_state do_atomic(struct rxe_qp *qp,
 368                                         struct rxe_pkt_info *pkt,
 369                                         struct rxe_send_wqe *wqe)
 370 {
 371         struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
 372         int ret;
 373
 374         u64 atomic_orig = atmack_orig(pkt);
 375
 376         ret = copy_data(rxe, qp->pd, IB_ACCESS_LOCAL_WRITE,
 377                         &wqe->dma, &atomic_orig,
 378                         sizeof(u64), to_mem_obj, NULL);
 379         if (ret)
 380                 return COMPST_ERROR;
 381         else
 382                 return COMPST_COMP_ACK;
 383 }
 384
 385 static void make_send_cqe(struct rxe_qp *qp, struct rxe_send_wqe *wqe,
 386                           struct rxe_cqe *cqe)
 387 {
 388         memset(cqe, 0, sizeof(*cqe));
 389
 390         if (!qp->is_user) {
 391                 struct ib_wc            *wc     = &cqe->ibwc;
 392
 393                 wc->wr_id               = wqe->wr.wr_id;
 394                 wc->status              = wqe->status;
 395                 wc->opcode              = wr_to_wc_opcode(wqe->wr.opcode);
 396                 if (wqe->wr.opcode == IB_WR_RDMA_WRITE_WITH_IMM ||
 397                     wqe->wr.opcode == IB_WR_SEND_WITH_IMM)
 398                         wc->wc_flags = IB_WC_WITH_IMM;
 399                 wc->byte_len            = wqe->dma.length;
 400                 wc->qp                  = &qp->ibqp;
 401         } else {
 402                 struct ib_uverbs_wc     *uwc    = &cqe->uibwc;
 403
 404                 uwc->wr_id              = wqe->wr.wr_id;
 405                 uwc->status             = wqe->status;
 406                 uwc->opcode             = wr_to_wc_opcode(wqe->wr.opcode);
 407                 if (wqe->wr.opcode == IB_WR_RDMA_WRITE_WITH_IMM ||
 408                     wqe->wr.opcode == IB_WR_SEND_WITH_IMM)
 409                         uwc->wc_flags = IB_WC_WITH_IMM;
 410                 uwc->byte_len           = wqe->dma.length;
 411                 uwc->qp_num             = qp->ibqp.qp_num;
 412         }
 413 }
 414
 415 static void do_complete(struct rxe_qp *qp, struct rxe_send_wqe *wqe)
 416 {
 417         struct rxe_cqe cqe;
 418
 419         if ((qp->sq_sig_type == IB_SIGNAL_ALL_WR) ||
 420             (wqe->wr.send_flags & IB_SEND_SIGNALED) ||
 421             (qp->req.state == QP_STATE_ERROR)) {
 422                 make_send_cqe(qp, wqe, &cqe);
 423                 advance_consumer(qp->sq.queue);
 424                 rxe_cq_post(qp->scq, &cqe, 0);
 425         } else {
 426                 advance_consumer(qp->sq.queue);
 427         }
 428
 429         /*
 430          * we completed something so let req run again
 431          * if it is trying to fence
 432          */
 433         if (qp->req.wait_fence) {
 434                 qp->req.wait_fence = 0;
 435                 rxe_run_task(&qp->req.task, 1);
 436         }
 437 }
 438
 439 static inline enum comp_state complete_ack(struct rxe_qp *qp,
 440                                            struct rxe_pkt_info *pkt,
 441                                            struct rxe_send_wqe *wqe)
 442 {
 443         unsigned long flags;
 444
 445         if (wqe->has_rd_atomic) {
 446                 wqe->has_rd_atomic = 0;
 447                 atomic_inc(&qp->req.rd_atomic);
 448                 if (qp->req.need_rd_atomic) {
 449                         qp->comp.timeout_retry = 0;
 450                         qp->req.need_rd_atomic = 0;
 451                         rxe_run_task(&qp->req.task, 1);
 452                 }
 453         }
 454
 455         if (unlikely(qp->req.state == QP_STATE_DRAIN)) {
 456                 /* state_lock used by requester & completer */
 457                 spin_lock_irqsave(&qp->state_lock, flags);
 458                 if ((qp->req.state == QP_STATE_DRAIN) &&
 459                     (qp->comp.psn == qp->req.psn)) {
 460                         qp->req.state = QP_STATE_DRAINED;
 461                         spin_unlock_irqrestore(&qp->state_lock, flags);
 462
 463                         if (qp->ibqp.event_handler) {
 464                                 struct ib_event ev;
 465
 466                                 ev.device = qp->ibqp.device;
 467                                 ev.element.qp = &qp->ibqp;
 468                                 ev.event = IB_EVENT_SQ_DRAINED;
 469                                 qp->ibqp.event_handler(&ev,
 470                                         qp->ibqp.qp_context);
 471                         }
 472                 } else {
 473                         spin_unlock_irqrestore(&qp->state_lock, flags);
 474                 }
 475         }
 476
 477         do_complete(qp, wqe);
 478
 479         if (psn_compare(pkt->psn, qp->comp.psn) >= 0)
 480                 return COMPST_UPDATE_COMP;
 481         else
 482                 return COMPST_DONE;
 483 }
 484
 485 static inline enum comp_state complete_wqe(struct rxe_qp *qp,
 486                                            struct rxe_pkt_info *pkt,
 487                                            struct rxe_send_wqe *wqe)
 488 {
 489         qp->comp.opcode = -1;
 490
 491         if (pkt) {
 492                 if (psn_compare(pkt->psn, qp->comp.psn) >= 0)
 493                         qp->comp.psn = (pkt->psn + 1) & BTH_PSN_MASK;
 494
 495                 if (qp->req.wait_psn) {
 496                         qp->req.wait_psn = 0;
 497                         rxe_run_task(&qp->req.task, 1);
 498                 }
 499         }
 500
 501         do_complete(qp, wqe);
 502
 503         return COMPST_GET_WQE;
 504 }
 505
 506 int rxe_completer(void *arg)
 507 {
 508         struct rxe_qp *qp = (struct rxe_qp *)arg;
 509         struct rxe_send_wqe *wqe = wqe;
 510         struct sk_buff *skb = NULL;
 511         struct rxe_pkt_info *pkt = NULL;
 512         enum comp_state state;
 513
 514         rxe_add_ref(qp);
 515
 516         if (!qp->valid) {
 517                 while ((skb = skb_dequeue(&qp->resp_pkts))) {
 518                         rxe_drop_ref(qp);
 519                         kfree_skb(skb);
 520                 }
 521                 skb = NULL;
 522                 pkt = NULL;
 523
 524                 while (queue_head(qp->sq.queue))
 525                         advance_consumer(qp->sq.queue);
 526
 527                 goto exit;
 528         }
 529
 530         if (qp->req.state == QP_STATE_ERROR) {
 531                 while ((skb = skb_dequeue(&qp->resp_pkts))) {
 532                         rxe_drop_ref(qp);
 533                         kfree_skb(skb);
 534                 }
 535                 skb = NULL;
 536                 pkt = NULL;
 537
 538                 while ((wqe = queue_head(qp->sq.queue))) {
 539                         wqe->status = IB_WC_WR_FLUSH_ERR;
 540                         do_complete(qp, wqe);
 541                 }
 542
 543                 goto exit;
 544         }
 545
 546         if (qp->req.state == QP_STATE_RESET) {
 547                 while ((skb = skb_dequeue(&qp->resp_pkts))) {
 548                         rxe_drop_ref(qp);
 549                         kfree_skb(skb);
 550                 }
 551                 skb = NULL;
 552                 pkt = NULL;
 553
 554                 while (queue_head(qp->sq.queue))
 555                         advance_consumer(qp->sq.queue);
 556
 557                 goto exit;
 558         }
 559
 560         if (qp->comp.timeout) {
 561                 qp->comp.timeout_retry = 1;
 562                 qp->comp.timeout = 0;
 563         } else {
 564                 qp->comp.timeout_retry = 0;
 565         }
 566
 567         if (qp->req.need_retry)
 568                 goto exit;
 569
 570         state = COMPST_GET_ACK;
 571
 572         while (1) {
 573                 pr_debug("qp#%d state = %s\n", qp_num(qp),
 574                          comp_state_name[state]);
 575                 switch (state) {
 576                 case COMPST_GET_ACK:
 577                         skb = skb_dequeue(&qp->resp_pkts);
 578                         if (skb) {
 579                                 pkt = SKB_TO_PKT(skb);
 580                                 qp->comp.timeout_retry = 0;
 581                         }
 582                         state = COMPST_GET_WQE;
 583                         break;
 584
 585                 case COMPST_GET_WQE:
 586                         state = get_wqe(qp, pkt, &wqe);
 587                         break;
 588
 589                 case COMPST_CHECK_PSN:
 590                         state = check_psn(qp, pkt, wqe);
 591                         break;
 592
 593                 case COMPST_CHECK_ACK:
 594                         state = check_ack(qp, pkt, wqe);
 595                         break;
 596
 597                 case COMPST_READ:
 598                         state = do_read(qp, pkt, wqe);
 599                         break;
 600
 601                 case COMPST_ATOMIC:
 602                         state = do_atomic(qp, pkt, wqe);
 603                         break;
 604
 605                 case COMPST_WRITE_SEND:
 606                         if (wqe->state == wqe_state_pending &&
 607                             wqe->last_psn == pkt->psn)
 608                                 state = COMPST_COMP_ACK;
 609                         else
 610                                 state = COMPST_UPDATE_COMP;
 611                         break;
 612
 613                 case COMPST_COMP_ACK:
 614                         state = complete_ack(qp, pkt, wqe);
 615                         break;
 616
 617                 case COMPST_COMP_WQE:
 618                         state = complete_wqe(qp, pkt, wqe);
 619                         break;
 620
 621                 case COMPST_UPDATE_COMP:
 622                         if (pkt->mask & RXE_END_MASK)
 623                                 qp->comp.opcode = -1;
 624                         else
 625                                 qp->comp.opcode = pkt->opcode;
 626
 627                         if (psn_compare(pkt->psn, qp->comp.psn) >= 0)
 628                                 qp->comp.psn = (pkt->psn + 1) & BTH_PSN_MASK;
 629
 630                         if (qp->req.wait_psn) {
 631                                 qp->req.wait_psn = 0;
 632                                 rxe_run_task(&qp->req.task, 1);
 633                         }
 634
 635                         state = COMPST_DONE;
 636                         break;
 637
 638                 case COMPST_DONE:
 639                         if (pkt) {
 640                                 rxe_drop_ref(pkt->qp);
 641                                 kfree_skb(skb);
 642                         }
 643                         goto done;
 644
 645                 case COMPST_EXIT:
 646                         if (qp->comp.timeout_retry && wqe) {
 647                                 state = COMPST_ERROR_RETRY;
 648                                 break;
 649                         }
 650
 651                         /* re reset the timeout counter if
 652                          * (1) QP is type RC
 653                          * (2) the QP is alive
 654                          * (3) there is a packet sent by the requester that
 655                          *     might be acked (we still might get spurious
 656                          *     timeouts but try to keep them as few as possible)
 657                          * (4) the timeout parameter is set
 658                          */
 659                         if ((qp_type(qp) == IB_QPT_RC) &&
 660                             (qp->req.state == QP_STATE_READY) &&
 661                             (psn_compare(qp->req.psn, qp->comp.psn) > 0) &&
 662                             qp->qp_timeout_jiffies)
 663                                 mod_timer(&qp->retrans_timer,
 664                                           jiffies + qp->qp_timeout_jiffies);
 665                         goto exit;
 666
 667                 case COMPST_ERROR_RETRY:
 668                         /* we come here if the retry timer fired and we did
 669                          * not receive a response packet. try to retry the send
 670                          * queue if that makes sense and the limits have not
 671                          * been exceeded. remember that some timeouts are
 672                          * spurious since we do not reset the timer but kick
 673                          * it down the road or let it expire
 674                          */
 675
 676                         /* there is nothing to retry in this case */
 677                         if (!wqe || (wqe->state == wqe_state_posted))
 678                                 goto exit;
 679
 680                         if (qp->comp.retry_cnt > 0) {
 681                                 if (qp->comp.retry_cnt != 7)
 682                                         qp->comp.retry_cnt--;
 683
 684                                 /* no point in retrying if we have already
 685                                  * seen the last ack that the requester could
 686                                  * have caused
 687                                  */
 688                                 if (psn_compare(qp->req.psn,
 689                                                 qp->comp.psn) > 0) {
 690                                         /* tell the requester to retry the
 691                                          * send send queue next time around
 692                                          */
 693                                         qp->req.need_retry = 1;
 694                                         rxe_run_task(&qp->req.task, 1);
 695                                 }
 696
 697                                 if (pkt) {
 698                                         rxe_drop_ref(pkt->qp);
 699                                         kfree_skb(skb);
 700                                 }
 701
 702                                 goto exit;
 703
 704                         } else {
 705                                 wqe->status = IB_WC_RETRY_EXC_ERR;
 706                                 state = COMPST_ERROR;
 707                         }
 708                         break;
 709
 710                 case COMPST_RNR_RETRY:
 711                         if (qp->comp.rnr_retry > 0) {
 712                                 if (qp->comp.rnr_retry != 7)
 713                                         qp->comp.rnr_retry--;
 714
 715                                 qp->req.need_retry = 1;
 716                                 pr_debug("qp#%d set rnr nak timer\n",
 717                                          qp_num(qp));
 718                                 mod_timer(&qp->rnr_nak_timer,
 719                                           jiffies + rnrnak_jiffies(aeth_syn(pkt)
 720                                                 & ~AETH_TYPE_MASK));
 721                                 goto exit;
 722                         } else {
 723                                 wqe->status = IB_WC_RNR_RETRY_EXC_ERR;
 724                                 state = COMPST_ERROR;
 725                         }
 726                         break;
 727
 728                 case COMPST_ERROR:
 729                         do_complete(qp, wqe);
 730                         rxe_qp_error(qp);
 731
 732                         if (pkt) {
 733                                 rxe_drop_ref(pkt->qp);
 734                                 kfree_skb(skb);
 735                         }
 736
 737                         goto exit;
 738                 }
 739         }
 740
 741 exit:
 742         /* we come here if we are done with processing and want the task to
 743          * exit from the loop calling us
 744          */
 745         rxe_drop_ref(qp);
 746         return -EAGAIN;
 747
 748 done:
 749         /* we come here if we have processed a packet we want the task to call
 750          * us again to see if there is anything else to do
 751          */
 752         rxe_drop_ref(qp);
 753         return 0;
 754 }