/*
 * Copyright (c) 2016 Mellanox Technologies Ltd. All rights reserved.
 * Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/skbuff.h>

#include "rxe.h"
#include "rxe_loc.h"
#include "rxe_queue.h"
#include "rxe_task.h"

enum comp_state {
        COMPST_GET_ACK,
        COMPST_GET_WQE,
        COMPST_COMP_WQE,
        COMPST_COMP_ACK,
        COMPST_CHECK_PSN,
        COMPST_CHECK_ACK,
        COMPST_READ,
        COMPST_ATOMIC,
        COMPST_WRITE_SEND,
        COMPST_UPDATE_COMP,
        COMPST_ERROR_RETRY,
        COMPST_RNR_RETRY,
        COMPST_ERROR,
        COMPST_EXIT, /* We have an issue, and we want to rerun the completer */
        COMPST_DONE, /* The completer finished successflly */
};

static char *comp_state_name[] =  {
        [COMPST_GET_ACK]                = "GET ACK",
        [COMPST_GET_WQE]                = "GET WQE",
        [COMPST_COMP_WQE]               = "COMP WQE",
        [COMPST_COMP_ACK]               = "COMP ACK",
        [COMPST_CHECK_PSN]              = "CHECK PSN",
        [COMPST_CHECK_ACK]              = "CHECK ACK",
        [COMPST_READ]                   = "READ",
        [COMPST_ATOMIC]                 = "ATOMIC",
        [COMPST_WRITE_SEND]             = "WRITE/SEND",
        [COMPST_UPDATE_COMP]            = "UPDATE COMP",
        [COMPST_ERROR_RETRY]            = "ERROR RETRY",
        [COMPST_RNR_RETRY]              = "RNR RETRY",
        [COMPST_ERROR]                  = "ERROR",
        [COMPST_EXIT]                   = "EXIT",
        [COMPST_DONE]                   = "DONE",
};

static unsigned long rnrnak_usec[32] = {
        [IB_RNR_TIMER_655_36] = 655360,
        [IB_RNR_TIMER_000_01] = 10,
        [IB_RNR_TIMER_000_02] = 20,
        [IB_RNR_TIMER_000_03] = 30,
        [IB_RNR_TIMER_000_04] = 40,
        [IB_RNR_TIMER_000_06] = 60,
        [IB_RNR_TIMER_000_08] = 80,
        [IB_RNR_TIMER_000_12] = 120,
        [IB_RNR_TIMER_000_16] = 160,
        [IB_RNR_TIMER_000_24] = 240,
        [IB_RNR_TIMER_000_32] = 320,
        [IB_RNR_TIMER_000_48] = 480,
        [IB_RNR_TIMER_000_64] = 640,
        [IB_RNR_TIMER_000_96] = 960,
        [IB_RNR_TIMER_001_28] = 1280,
        [IB_RNR_TIMER_001_92] = 1920,
        [IB_RNR_TIMER_002_56] = 2560,
        [IB_RNR_TIMER_003_84] = 3840,
        [IB_RNR_TIMER_005_12] = 5120,
        [IB_RNR_TIMER_007_68] = 7680,
        [IB_RNR_TIMER_010_24] = 10240,
        [IB_RNR_TIMER_015_36] = 15360,
        [IB_RNR_TIMER_020_48] = 20480,
        [IB_RNR_TIMER_030_72] = 30720,
        [IB_RNR_TIMER_040_96] = 40960,
        [IB_RNR_TIMER_061_44] = 61410,
        [IB_RNR_TIMER_081_92] = 81920,
        [IB_RNR_TIMER_122_88] = 122880,
        [IB_RNR_TIMER_163_84] = 163840,
        [IB_RNR_TIMER_245_76] = 245760,
        [IB_RNR_TIMER_327_68] = 327680,
        [IB_RNR_TIMER_491_52] = 491520,
};

static inline unsigned long rnrnak_jiffies(u8 timeout)
{
        return max_t(unsigned long,
                usecs_to_jiffies(rnrnak_usec[timeout]), 1);
}

static enum ib_wc_opcode wr_to_wc_opcode(enum ib_wr_opcode opcode)
{
        switch (opcode) {
        case IB_WR_RDMA_WRITE:                  return IB_WC_RDMA_WRITE;
        case IB_WR_RDMA_WRITE_WITH_IMM:         return IB_WC_RDMA_WRITE;
        case IB_WR_SEND:                        return IB_WC_SEND;
        case IB_WR_SEND_WITH_IMM:               return IB_WC_SEND;
        case IB_WR_RDMA_READ:                   return IB_WC_RDMA_READ;
        case IB_WR_ATOMIC_CMP_AND_SWP:          return IB_WC_COMP_SWAP;
        case IB_WR_ATOMIC_FETCH_AND_ADD:        return IB_WC_FETCH_ADD;
        case IB_WR_LSO:                         return IB_WC_LSO;
        case IB_WR_SEND_WITH_INV:               return IB_WC_SEND;
        case IB_WR_RDMA_READ_WITH_INV:          return IB_WC_RDMA_READ;
        case IB_WR_LOCAL_INV:                   return IB_WC_LOCAL_INV;
        case IB_WR_REG_MR:                      return IB_WC_REG_MR;

        default:
                return 0xff;
        }
}

void retransmit_timer(unsigned long data)
{
        struct rxe_qp *qp = (struct rxe_qp *)data;

        if (qp->valid) {
                qp->comp.timeout = 1;
                rxe_run_task(&qp->comp.task, 1);
        }
}

void rxe_comp_queue_pkt(struct rxe_dev *rxe, struct rxe_qp *qp,
                        struct sk_buff *skb)
{
        int must_sched;

        skb_queue_tail(&qp->resp_pkts, skb);

        must_sched = skb_queue_len(&qp->resp_pkts) > 1;
        if (must_sched != 0)
                rxe_counter_inc(rxe, RXE_CNT_COMPLETER_SCHED);
        rxe_run_task(&qp->comp.task, must_sched);
}

static inline enum comp_state get_wqe(struct rxe_qp *qp,
                                      struct rxe_pkt_info *pkt,
                                      struct rxe_send_wqe **wqe_p)
{
        struct rxe_send_wqe *wqe;

        /* we come here whether or not we found a response packet to see if
         * there are any posted WQEs
         */
        wqe = queue_head(qp->sq.queue);
        *wqe_p = wqe;

        /* no WQE or requester has not started it yet */
        if (!wqe || wqe->state == wqe_state_posted)
                return pkt ? COMPST_DONE : COMPST_EXIT;

        /* WQE does not require an ack */
        if (wqe->state == wqe_state_done)
                return COMPST_COMP_WQE;

        /* WQE caused an error */
        if (wqe->state == wqe_state_error)
                return COMPST_ERROR;

        /* we have a WQE, if we also have an ack check its PSN */
        return pkt ? COMPST_CHECK_PSN : COMPST_EXIT;
}

static inline void reset_retry_counters(struct rxe_qp *qp)
{
        qp->comp.retry_cnt = qp->attr.retry_cnt;
        qp->comp.rnr_retry = qp->attr.rnr_retry;
}

static inline enum comp_state check_psn(struct rxe_qp *qp,
                                        struct rxe_pkt_info *pkt,
                                        struct rxe_send_wqe *wqe)
{
        s32 diff;

        /* check to see if response is past the oldest WQE. if it is, complete
         * send/write or error read/atomic
         */
        diff = psn_compare(pkt->psn, wqe->last_psn);
        if (diff > 0) {
                if (wqe->state == wqe_state_pending) {
                        if (wqe->mask & WR_ATOMIC_OR_READ_MASK)
                                return COMPST_ERROR_RETRY;

                        reset_retry_counters(qp);
                        return COMPST_COMP_WQE;
                } else {
                        return COMPST_DONE;
                }
        }

        /* compare response packet to expected response */
        diff = psn_compare(pkt->psn, qp->comp.psn);
        if (diff < 0) {
                /* response is most likely a retried packet if it matches an
                 * uncompleted WQE go complete it else ignore it
                 */
                if (pkt->psn == wqe->last_psn)
                        return COMPST_COMP_ACK;
                else
                        return COMPST_DONE;
        } else if ((diff > 0) && (wqe->mask & WR_ATOMIC_OR_READ_MASK)) {
                return COMPST_DONE;
        } else {
                return COMPST_CHECK_ACK;
        }
}

static inline enum comp_state check_ack(struct rxe_qp *qp,
                                        struct rxe_pkt_info *pkt,
                                        struct rxe_send_wqe *wqe)
{
        unsigned int mask = pkt->mask;
        u8 syn;
        struct rxe_dev *rxe = to_rdev(qp->ibqp.device);

        /* Check the sequence only */
        switch (qp->comp.opcode) {
        case -1:
                /* Will catch all *_ONLY cases. */
                if (!(mask & RXE_START_MASK))
                        return COMPST_ERROR;

                break;

        case IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST:
        case IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE:
                if (pkt->opcode != IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE &&
                    pkt->opcode != IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST) {
                        return COMPST_ERROR;
                }
                break;
        default:
                WARN_ON_ONCE(1);
        }

        /* Check operation validity. */
        switch (pkt->opcode) {
        case IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST:
        case IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST:
        case IB_OPCODE_RC_RDMA_READ_RESPONSE_ONLY:
                syn = aeth_syn(pkt);

                if ((syn & AETH_TYPE_MASK) != AETH_ACK)
                        return COMPST_ERROR;

                /* Fall through (IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE
                 * doesn't have an AETH)
                 */
        case IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE:
                if (wqe->wr.opcode != IB_WR_RDMA_READ &&
                    wqe->wr.opcode != IB_WR_RDMA_READ_WITH_INV) {
                        return COMPST_ERROR;
                }
                reset_retry_counters(qp);
                return COMPST_READ;

        case IB_OPCODE_RC_ATOMIC_ACKNOWLEDGE:
                syn = aeth_syn(pkt);

                if ((syn & AETH_TYPE_MASK) != AETH_ACK)
                        return COMPST_ERROR;

                if (wqe->wr.opcode != IB_WR_ATOMIC_CMP_AND_SWP &&
                    wqe->wr.opcode != IB_WR_ATOMIC_FETCH_AND_ADD)
                        return COMPST_ERROR;
                reset_retry_counters(qp);
                return COMPST_ATOMIC;

        case IB_OPCODE_RC_ACKNOWLEDGE:
                syn = aeth_syn(pkt);
                switch (syn & AETH_TYPE_MASK) {
                case AETH_ACK:
                        reset_retry_counters(qp);
                        return COMPST_WRITE_SEND;

                case AETH_RNR_NAK:
                        rxe_counter_inc(rxe, RXE_CNT_RCV_RNR);
                        return COMPST_RNR_RETRY;

                case AETH_NAK:
                        switch (syn) {
                        case AETH_NAK_PSN_SEQ_ERROR:
                                /* a nak implicitly acks all packets with psns
                                 * before
                                 */
                                if (psn_compare(pkt->psn, qp->comp.psn) > 0) {
                                        rxe_counter_inc(rxe,
                                                        RXE_CNT_RCV_SEQ_ERR);
                                        qp->comp.psn = pkt->psn;
                                        if (qp->req.wait_psn) {
                                                qp->req.wait_psn = 0;
                                                rxe_run_task(&qp->req.task, 1);
                                        }
                                }
                                return COMPST_ERROR_RETRY;

                        case AETH_NAK_INVALID_REQ:
                                wqe->status = IB_WC_REM_INV_REQ_ERR;
                                return COMPST_ERROR;

                        case AETH_NAK_REM_ACC_ERR:
                                wqe->status = IB_WC_REM_ACCESS_ERR;
                                return COMPST_ERROR;

                        case AETH_NAK_REM_OP_ERR:
                                wqe->status = IB_WC_REM_OP_ERR;
                                return COMPST_ERROR;

                        default:
                                pr_warn("unexpected nak %x\n", syn);
                                wqe->status = IB_WC_REM_OP_ERR;
                                return COMPST_ERROR;
                        }

                default:
                        return COMPST_ERROR;
                }
                break;

        default:
                pr_warn("unexpected opcode\n");
        }

        return COMPST_ERROR;
}

static inline enum comp_state do_read(struct rxe_qp *qp,
                                      struct rxe_pkt_info *pkt,
                                      struct rxe_send_wqe *wqe)
{
        struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
        int ret;

        ret = copy_data(rxe, qp->pd, IB_ACCESS_LOCAL_WRITE,
                        &wqe->dma, payload_addr(pkt),
                        payload_size(pkt), to_mem_obj, NULL);
        if (ret)
                return COMPST_ERROR;

        if (wqe->dma.resid == 0 && (pkt->mask & RXE_END_MASK))
                return COMPST_COMP_ACK;
        else
                return COMPST_UPDATE_COMP;
}

static inline enum comp_state do_atomic(struct rxe_qp *qp,
                                        struct rxe_pkt_info *pkt,
                                        struct rxe_send_wqe *wqe)
{
        struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
        int ret;

        u64 atomic_orig = atmack_orig(pkt);

        ret = copy_data(rxe, qp->pd, IB_ACCESS_LOCAL_WRITE,
                        &wqe->dma, &atomic_orig,
                        sizeof(u64), to_mem_obj, NULL);
        if (ret)
                return COMPST_ERROR;
        else
                return COMPST_COMP_ACK;
}

static void make_send_cqe(struct rxe_qp *qp, struct rxe_send_wqe *wqe,
                          struct rxe_cqe *cqe)
{
        memset(cqe, 0, sizeof(*cqe));

        if (!qp->is_user) {
                struct ib_wc            *wc     = &cqe->ibwc;

                wc->wr_id               = wqe->wr.wr_id;
                wc->status              = wqe->status;
                wc->opcode              = wr_to_wc_opcode(wqe->wr.opcode);
                if (wqe->wr.opcode == IB_WR_RDMA_WRITE_WITH_IMM ||
                    wqe->wr.opcode == IB_WR_SEND_WITH_IMM)
                        wc->wc_flags = IB_WC_WITH_IMM;
                wc->byte_len            = wqe->dma.length;
                wc->qp                  = &qp->ibqp;
        } else {
                struct ib_uverbs_wc     *uwc    = &cqe->uibwc;

                uwc->wr_id              = wqe->wr.wr_id;
                uwc->status             = wqe->status;
                uwc->opcode             = wr_to_wc_opcode(wqe->wr.opcode);
                if (wqe->wr.opcode == IB_WR_RDMA_WRITE_WITH_IMM ||
                    wqe->wr.opcode == IB_WR_SEND_WITH_IMM)
                        uwc->wc_flags = IB_WC_WITH_IMM;
                uwc->byte_len           = wqe->dma.length;
                uwc->qp_num             = qp->ibqp.qp_num;
        }
}

/*
 * IBA Spec. Section 10.7.3.1 SIGNALED COMPLETIONS
 * ---------8<---------8<-------------
 * ...Note that if a completion error occurs, a Work Completion
 * will always be generated, even if the signaling
 * indicator requests an Unsignaled Completion.
 * ---------8<---------8<-------------
 */
static void do_complete(struct rxe_qp *qp, struct rxe_send_wqe *wqe)
{
        struct rxe_cqe cqe;

        if ((qp->sq_sig_type == IB_SIGNAL_ALL_WR) ||
            (wqe->wr.send_flags & IB_SEND_SIGNALED) ||
            wqe->status != IB_WC_SUCCESS) {
                make_send_cqe(qp, wqe, &cqe);
                advance_consumer(qp->sq.queue);
                rxe_cq_post(qp->scq, &cqe, 0);
        } else {
                advance_consumer(qp->sq.queue);
        }

        /*
         * we completed something so let req run again
         * if it is trying to fence
         */
        if (qp->req.wait_fence) {
                qp->req.wait_fence = 0;
                rxe_run_task(&qp->req.task, 1);
        }
}

static inline enum comp_state complete_ack(struct rxe_qp *qp,
                                           struct rxe_pkt_info *pkt,
                                           struct rxe_send_wqe *wqe)
{
        unsigned long flags;

        if (wqe->has_rd_atomic) {
                wqe->has_rd_atomic = 0;
                atomic_inc(&qp->req.rd_atomic);
                if (qp->req.need_rd_atomic) {
                        qp->comp.timeout_retry = 0;
                        qp->req.need_rd_atomic = 0;
                        rxe_run_task(&qp->req.task, 1);
                }
        }

        if (unlikely(qp->req.state == QP_STATE_DRAIN)) {
                /* state_lock used by requester & completer */
                spin_lock_irqsave(&qp->state_lock, flags);
                if ((qp->req.state == QP_STATE_DRAIN) &&
                    (qp->comp.psn == qp->req.psn)) {
                        qp->req.state = QP_STATE_DRAINED;
                        spin_unlock_irqrestore(&qp->state_lock, flags);

                        if (qp->ibqp.event_handler) {
                                struct ib_event ev;

                                ev.device = qp->ibqp.device;
                                ev.element.qp = &qp->ibqp;
                                ev.event = IB_EVENT_SQ_DRAINED;
                                qp->ibqp.event_handler(&ev,
                                        qp->ibqp.qp_context);
                        }
                } else {
                        spin_unlock_irqrestore(&qp->state_lock, flags);
                }
        }

        do_complete(qp, wqe);

        if (psn_compare(pkt->psn, qp->comp.psn) >= 0)
                return COMPST_UPDATE_COMP;
        else
                return COMPST_DONE;
}

static inline enum comp_state complete_wqe(struct rxe_qp *qp,
                                           struct rxe_pkt_info *pkt,
                                           struct rxe_send_wqe *wqe)
{
        qp->comp.opcode = -1;

        if (pkt) {
                if (psn_compare(pkt->psn, qp->comp.psn) >= 0)
                        qp->comp.psn = (pkt->psn + 1) & BTH_PSN_MASK;

                if (qp->req.wait_psn) {
                        qp->req.wait_psn = 0;
                        rxe_run_task(&qp->req.task, 1);
                }
        }

        do_complete(qp, wqe);

        return COMPST_GET_WQE;
}

static void rxe_drain_resp_pkts(struct rxe_qp *qp, bool notify)
{
        struct sk_buff *skb;
        struct rxe_send_wqe *wqe;

        while ((skb = skb_dequeue(&qp->resp_pkts))) {
                rxe_drop_ref(qp);
                kfree_skb(skb);
        }

        while ((wqe = queue_head(qp->sq.queue))) {
                if (notify) {
                        wqe->status = IB_WC_WR_FLUSH_ERR;
                        do_complete(qp, wqe);
                } else {
                        advance_consumer(qp->sq.queue);
                }
        }
}

int rxe_completer(void *arg)
{
        struct rxe_qp *qp = (struct rxe_qp *)arg;
        struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
        struct rxe_send_wqe *wqe = wqe;
        struct sk_buff *skb = NULL;
        struct rxe_pkt_info *pkt = NULL;
        enum comp_state state;

        rxe_add_ref(qp);

        if (!qp->valid || qp->req.state == QP_STATE_ERROR ||
            qp->req.state == QP_STATE_RESET) {
                rxe_drain_resp_pkts(qp, qp->valid &&
                                    qp->req.state == QP_STATE_ERROR);
                goto exit;
        }

        if (qp->comp.timeout) {
                qp->comp.timeout_retry = 1;
                qp->comp.timeout = 0;
        } else {
                qp->comp.timeout_retry = 0;
        }

        if (qp->req.need_retry)
                goto exit;

        state = COMPST_GET_ACK;

        while (1) {
                pr_debug("qp#%d state = %s\n", qp_num(qp),
                         comp_state_name[state]);
                switch (state) {
                case COMPST_GET_ACK:
                        skb = skb_dequeue(&qp->resp_pkts);
                        if (skb) {
                                pkt = SKB_TO_PKT(skb);
                                qp->comp.timeout_retry = 0;
                        }
                        state = COMPST_GET_WQE;
                        break;

                case COMPST_GET_WQE:
                        state = get_wqe(qp, pkt, &wqe);
                        break;

                case COMPST_CHECK_PSN:
                        state = check_psn(qp, pkt, wqe);
                        break;

                case COMPST_CHECK_ACK:
                        state = check_ack(qp, pkt, wqe);
                        break;

                case COMPST_READ:
                        state = do_read(qp, pkt, wqe);
                        break;

                case COMPST_ATOMIC:
                        state = do_atomic(qp, pkt, wqe);
                        break;

                case COMPST_WRITE_SEND:
                        if (wqe->state == wqe_state_pending &&
                            wqe->last_psn == pkt->psn)
                                state = COMPST_COMP_ACK;
                        else
                                state = COMPST_UPDATE_COMP;
                        break;

                case COMPST_COMP_ACK:
                        state = complete_ack(qp, pkt, wqe);
                        break;

                case COMPST_COMP_WQE:
                        state = complete_wqe(qp, pkt, wqe);
                        break;

                case COMPST_UPDATE_COMP:
                        if (pkt->mask & RXE_END_MASK)
                                qp->comp.opcode = -1;
                        else
                                qp->comp.opcode = pkt->opcode;

                        if (psn_compare(pkt->psn, qp->comp.psn) >= 0)
                                qp->comp.psn = (pkt->psn + 1) & BTH_PSN_MASK;

                        if (qp->req.wait_psn) {
                                qp->req.wait_psn = 0;
                                rxe_run_task(&qp->req.task, 1);
                        }

                        state = COMPST_DONE;
                        break;

                case COMPST_DONE:
                        if (pkt) {
                                rxe_drop_ref(pkt->qp);
                                kfree_skb(skb);
                                skb = NULL;
                        }
                        goto done;

                case COMPST_EXIT:
                        if (qp->comp.timeout_retry && wqe) {
                                state = COMPST_ERROR_RETRY;
                                break;
                        }

                        /* re reset the timeout counter if
                         * (1) QP is type RC
                         * (2) the QP is alive
                         * (3) there is a packet sent by the requester that
                         *     might be acked (we still might get spurious
                         *     timeouts but try to keep them as few as possible)
                         * (4) the timeout parameter is set
                         */
                        if ((qp_type(qp) == IB_QPT_RC) &&
                            (qp->req.state == QP_STATE_READY) &&
                            (psn_compare(qp->req.psn, qp->comp.psn) > 0) &&
                            qp->qp_timeout_jiffies)
                                mod_timer(&qp->retrans_timer,
                                          jiffies + qp->qp_timeout_jiffies);
                        WARN_ON_ONCE(skb);
                        goto exit;

                case COMPST_ERROR_RETRY:
                        /* we come here if the retry timer fired and we did
                         * not receive a response packet. try to retry the send
                         * queue if that makes sense and the limits have not
                         * been exceeded. remember that some timeouts are
                         * spurious since we do not reset the timer but kick
                         * it down the road or let it expire
                         */

                        /* there is nothing to retry in this case */
                        if (!wqe || (wqe->state == wqe_state_posted)) {
                                WARN_ON_ONCE(skb);
                                goto exit;
                        }

                        if (qp->comp.retry_cnt > 0) {
                                if (qp->comp.retry_cnt != 7)
                                        qp->comp.retry_cnt--;

                                /* no point in retrying if we have already
                                 * seen the last ack that the requester could
                                 * have caused
                                 */
                                if (psn_compare(qp->req.psn,
                                                qp->comp.psn) > 0) {
                                        /* tell the requester to retry the
                                         * send queue next time around
                                         */
                                        rxe_counter_inc(rxe,
                                                        RXE_CNT_COMP_RETRY);
                                        qp->req.need_retry = 1;
                                        rxe_run_task(&qp->req.task, 1);
                                }

                                if (pkt) {
                                        rxe_drop_ref(pkt->qp);
                                        kfree_skb(skb);
                                        skb = NULL;
                                }

                                WARN_ON_ONCE(skb);
                                goto exit;

                        } else {
                                rxe_counter_inc(rxe, RXE_CNT_RETRY_EXCEEDED);
                                wqe->status = IB_WC_RETRY_EXC_ERR;
                                state = COMPST_ERROR;
                        }
                        break;

                case COMPST_RNR_RETRY:
                        if (qp->comp.rnr_retry > 0) {
                                if (qp->comp.rnr_retry != 7)
                                        qp->comp.rnr_retry--;

                                qp->req.need_retry = 1;
                                pr_debug("qp#%d set rnr nak timer\n",
                                         qp_num(qp));
                                mod_timer(&qp->rnr_nak_timer,
                                          jiffies + rnrnak_jiffies(aeth_syn(pkt)
                                                & ~AETH_TYPE_MASK));
                                rxe_drop_ref(pkt->qp);
                                kfree_skb(skb);
                                skb = NULL;
                                goto exit;
                        } else {
                                rxe_counter_inc(rxe,
                                                RXE_CNT_RNR_RETRY_EXCEEDED);
                                wqe->status = IB_WC_RNR_RETRY_EXC_ERR;
                                state = COMPST_ERROR;
                        }
                        break;

                case COMPST_ERROR:
                        WARN_ON_ONCE(wqe->status == IB_WC_SUCCESS);
                        do_complete(qp, wqe);
                        rxe_qp_error(qp);

                        if (pkt) {
                                rxe_drop_ref(pkt->qp);
                                kfree_skb(skb);
                                skb = NULL;
                        }

                        WARN_ON_ONCE(skb);
                        goto exit;
                }
        }

exit:
        /* we come here if we are done with processing and want the task to
         * exit from the loop calling us
         */
        WARN_ON_ONCE(skb);
        rxe_drop_ref(qp);
        return -EAGAIN;

done:
        /* we come here if we have processed a packet we want the task to call
         * us again to see if there is anything else to do
         */
        WARN_ON_ONCE(skb);
        rxe_drop_ref(qp);
        return 0;
}