/*
 * Copyright(c) 2015 - 2018 Intel Corporation.
 *
 * This file is provided under a dual BSD/GPLv2 license.  When using or
 * redistributing this file, you may do so under either license.
 *
 * GPL LICENSE SUMMARY
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * BSD LICENSE
 *
 * 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.
 *  - Neither the name of Intel Corporation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <linux/io.h>
#include <rdma/rdma_vt.h>
#include <rdma/rdmavt_qp.h>

#include "hfi.h"
#include "qp.h"
#include "rc.h"
#include "verbs_txreq.h"
#include "trace.h"

struct rvt_ack_entry *find_prev_entry(struct rvt_qp *qp, u32 psn, u8 *prev,
                                      u8 *prev_ack, bool *scheduled)
        __must_hold(&qp->s_lock)
{
        struct rvt_ack_entry *e = NULL;
        u8 i, p;
        bool s = true;

        for (i = qp->r_head_ack_queue; ; i = p) {
                if (i == qp->s_tail_ack_queue)
                        s = false;
                if (i)
                        p = i - 1;
                else
                        p = rvt_size_atomic(ib_to_rvt(qp->ibqp.device));
                if (p == qp->r_head_ack_queue) {
                        e = NULL;
                        break;
                }
                e = &qp->s_ack_queue[p];
                if (!e->opcode) {
                        e = NULL;
                        break;
                }
                if (cmp_psn(psn, e->psn) >= 0) {
                        if (p == qp->s_tail_ack_queue &&
                            cmp_psn(psn, e->lpsn) <= 0)
                                s = false;
                        break;
                }
        }
        if (prev)
                *prev = p;
        if (prev_ack)
                *prev_ack = i;
        if (scheduled)
                *scheduled = s;
        return e;
}

/**
 * make_rc_ack - construct a response packet (ACK, NAK, or RDMA read)
 * @dev: the device for this QP
 * @qp: a pointer to the QP
 * @ohdr: a pointer to the IB header being constructed
 * @ps: the xmit packet state
 *
 * Return 1 if constructed; otherwise, return 0.
 * Note that we are in the responder's side of the QP context.
 * Note the QP s_lock must be held.
 */
static int make_rc_ack(struct hfi1_ibdev *dev, struct rvt_qp *qp,
                       struct ib_other_headers *ohdr,
                       struct hfi1_pkt_state *ps)
{
        struct rvt_ack_entry *e;
        u32 hwords, hdrlen;
        u32 len = 0;
        u32 bth0 = 0, bth2 = 0;
        u32 bth1 = qp->remote_qpn | (HFI1_CAP_IS_KSET(OPFN) << IB_BTHE_E_SHIFT);
        int middle = 0;
        u32 pmtu = qp->pmtu;
        struct hfi1_qp_priv *qpriv = qp->priv;
        bool last_pkt;
        u32 delta;
        u8 next = qp->s_tail_ack_queue;
        struct tid_rdma_request *req;

        trace_hfi1_rsp_make_rc_ack(qp, 0);
        lockdep_assert_held(&qp->s_lock);
        /* Don't send an ACK if we aren't supposed to. */
        if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK))
                goto bail;

        if (qpriv->hdr_type == HFI1_PKT_TYPE_9B)
                /* header size in 32-bit words LRH+BTH = (8+12)/4. */
                hwords = 5;
        else
                /* header size in 32-bit words 16B LRH+BTH = (16+12)/4. */
                hwords = 7;

        switch (qp->s_ack_state) {
        case OP(RDMA_READ_RESPONSE_LAST):
        case OP(RDMA_READ_RESPONSE_ONLY):
                e = &qp->s_ack_queue[qp->s_tail_ack_queue];
                release_rdma_sge_mr(e);
                /* FALLTHROUGH */
        case OP(ATOMIC_ACKNOWLEDGE):
                /*
                 * We can increment the tail pointer now that the last
                 * response has been sent instead of only being
                 * constructed.
                 */
                if (++next > rvt_size_atomic(&dev->rdi))
                        next = 0;
                /*
                 * Only advance the s_acked_ack_queue pointer if there
                 * have been no TID RDMA requests.
                 */
                e = &qp->s_ack_queue[qp->s_tail_ack_queue];
                if (e->opcode != TID_OP(WRITE_REQ) &&
                    qp->s_acked_ack_queue == qp->s_tail_ack_queue)
                        qp->s_acked_ack_queue = next;
                qp->s_tail_ack_queue = next;
                trace_hfi1_rsp_make_rc_ack(qp, e->psn);
                /* FALLTHROUGH */
        case OP(SEND_ONLY):
        case OP(ACKNOWLEDGE):
                /* Check for no next entry in the queue. */
                if (qp->r_head_ack_queue == qp->s_tail_ack_queue) {
                        if (qp->s_flags & RVT_S_ACK_PENDING)
                                goto normal;
                        goto bail;
                }

                e = &qp->s_ack_queue[qp->s_tail_ack_queue];
                /* Check for tid write fence */
                if ((qpriv->s_flags & HFI1_R_TID_WAIT_INTERLCK) ||
                    hfi1_tid_rdma_ack_interlock(qp, e)) {
                        iowait_set_flag(&qpriv->s_iowait, IOWAIT_PENDING_IB);
                        goto bail;
                }
                if (e->opcode == OP(RDMA_READ_REQUEST)) {
                        /*
                         * If a RDMA read response is being resent and
                         * we haven't seen the duplicate request yet,
                         * then stop sending the remaining responses the
                         * responder has seen until the requester re-sends it.
                         */
                        len = e->rdma_sge.sge_length;
                        if (len && !e->rdma_sge.mr) {
                                if (qp->s_acked_ack_queue ==
                                    qp->s_tail_ack_queue)
                                        qp->s_acked_ack_queue =
                                                qp->r_head_ack_queue;
                                qp->s_tail_ack_queue = qp->r_head_ack_queue;
                                goto bail;
                        }
                        /* Copy SGE state in case we need to resend */
                        ps->s_txreq->mr = e->rdma_sge.mr;
                        if (ps->s_txreq->mr)
                                rvt_get_mr(ps->s_txreq->mr);
                        qp->s_ack_rdma_sge.sge = e->rdma_sge;
                        qp->s_ack_rdma_sge.num_sge = 1;
                        ps->s_txreq->ss = &qp->s_ack_rdma_sge;
                        if (len > pmtu) {
                                len = pmtu;
                                qp->s_ack_state = OP(RDMA_READ_RESPONSE_FIRST);
                        } else {
                                qp->s_ack_state = OP(RDMA_READ_RESPONSE_ONLY);
                                e->sent = 1;
                        }
                        ohdr->u.aeth = rvt_compute_aeth(qp);
                        hwords++;
                        qp->s_ack_rdma_psn = e->psn;
                        bth2 = mask_psn(qp->s_ack_rdma_psn++);
                } else if (e->opcode == TID_OP(WRITE_REQ)) {
                        /*
                         * If a TID RDMA WRITE RESP is being resent, we have to
                         * wait for the actual request. All requests that are to
                         * be resent will have their state set to
                         * TID_REQUEST_RESEND. When the new request arrives, the
                         * state will be changed to TID_REQUEST_RESEND_ACTIVE.
                         */
                        req = ack_to_tid_req(e);
                        if (req->state == TID_REQUEST_RESEND ||
                            req->state == TID_REQUEST_INIT_RESEND)
                                goto bail;
                        qp->s_ack_state = TID_OP(WRITE_RESP);
                        qp->s_ack_rdma_psn = mask_psn(e->psn + req->cur_seg);
                        goto write_resp;
                } else if (e->opcode == TID_OP(READ_REQ)) {
                        /*
                         * If a TID RDMA read response is being resent and
                         * we haven't seen the duplicate request yet,
                         * then stop sending the remaining responses the
                         * responder has seen until the requester re-sends it.
                         */
                        len = e->rdma_sge.sge_length;
                        if (len && !e->rdma_sge.mr) {
                                if (qp->s_acked_ack_queue ==
                                    qp->s_tail_ack_queue)
                                        qp->s_acked_ack_queue =
                                                qp->r_head_ack_queue;
                                qp->s_tail_ack_queue = qp->r_head_ack_queue;
                                goto bail;
                        }
                        /* Copy SGE state in case we need to resend */
                        ps->s_txreq->mr = e->rdma_sge.mr;
                        if (ps->s_txreq->mr)
                                rvt_get_mr(ps->s_txreq->mr);
                        qp->s_ack_rdma_sge.sge = e->rdma_sge;
                        qp->s_ack_rdma_sge.num_sge = 1;
                        qp->s_ack_state = TID_OP(READ_RESP);
                        goto read_resp;
                } else {
                        /* COMPARE_SWAP or FETCH_ADD */
                        ps->s_txreq->ss = NULL;
                        len = 0;
                        qp->s_ack_state = OP(ATOMIC_ACKNOWLEDGE);
                        ohdr->u.at.aeth = rvt_compute_aeth(qp);
                        ib_u64_put(e->atomic_data, &ohdr->u.at.atomic_ack_eth);
                        hwords += sizeof(ohdr->u.at) / sizeof(u32);
                        bth2 = mask_psn(e->psn);
                        e->sent = 1;
                }
                trace_hfi1_tid_write_rsp_make_rc_ack(qp);
                bth0 = qp->s_ack_state << 24;
                break;

        case OP(RDMA_READ_RESPONSE_FIRST):
                qp->s_ack_state = OP(RDMA_READ_RESPONSE_MIDDLE);
                /* FALLTHROUGH */
        case OP(RDMA_READ_RESPONSE_MIDDLE):
                ps->s_txreq->ss = &qp->s_ack_rdma_sge;
                ps->s_txreq->mr = qp->s_ack_rdma_sge.sge.mr;
                if (ps->s_txreq->mr)
                        rvt_get_mr(ps->s_txreq->mr);
                len = qp->s_ack_rdma_sge.sge.sge_length;
                if (len > pmtu) {
                        len = pmtu;
                        middle = HFI1_CAP_IS_KSET(SDMA_AHG);
                } else {
                        ohdr->u.aeth = rvt_compute_aeth(qp);
                        hwords++;
                        qp->s_ack_state = OP(RDMA_READ_RESPONSE_LAST);
                        e = &qp->s_ack_queue[qp->s_tail_ack_queue];
                        e->sent = 1;
                }
                bth0 = qp->s_ack_state << 24;
                bth2 = mask_psn(qp->s_ack_rdma_psn++);
                break;

        case TID_OP(WRITE_RESP):
write_resp:
                /*
                 * 1. Check if RVT_S_ACK_PENDING is set. If yes,
                 *    goto normal.
                 * 2. Attempt to allocate TID resources.
                 * 3. Remove RVT_S_RESP_PENDING flags from s_flags
                 * 4. If resources not available:
                 *    4.1 Set RVT_S_WAIT_TID_SPACE
                 *    4.2 Queue QP on RCD TID queue
                 *    4.3 Put QP on iowait list.
                 *    4.4 Build IB RNR NAK with appropriate timeout value
                 *    4.5 Return indication progress made.
                 * 5. If resources are available:
                 *    5.1 Program HW flow CSRs
                 *    5.2 Build TID RDMA WRITE RESP packet
                 *    5.3 If more resources needed, do 2.1 - 2.3.
                 *    5.4 Wake up next QP on RCD TID queue.
                 *    5.5 Return indication progress made.
                 */

                e = &qp->s_ack_queue[qp->s_tail_ack_queue];
                req = ack_to_tid_req(e);

                /*
                 * Send scheduled RNR NAK's. RNR NAK's need to be sent at
                 * segment boundaries, not at request boundaries. Don't change
                 * s_ack_state because we are still in the middle of a request
                 */
                if (qpriv->rnr_nak_state == TID_RNR_NAK_SEND &&
                    qp->s_tail_ack_queue == qpriv->r_tid_alloc &&
                    req->cur_seg == req->alloc_seg) {
                        qpriv->rnr_nak_state = TID_RNR_NAK_SENT;
                        goto normal_no_state;
                }

                bth2 = mask_psn(qp->s_ack_rdma_psn);
                hdrlen = hfi1_build_tid_rdma_write_resp(qp, e, ohdr, &bth1,
                                                        bth2, &len,
                                                        &ps->s_txreq->ss);
                if (!hdrlen)
                        return 0;

                hwords += hdrlen;
                bth0 = qp->s_ack_state << 24;
                qp->s_ack_rdma_psn++;
                trace_hfi1_tid_req_make_rc_ack_write(qp, 0, e->opcode, e->psn,
                                                     e->lpsn, req);
                if (req->cur_seg != req->total_segs)
                        break;

                e->sent = 1;
                /* Do not free e->rdma_sge until all data are received */
                qp->s_ack_state = OP(ATOMIC_ACKNOWLEDGE);
                break;

        case TID_OP(READ_RESP):
read_resp:
                e = &qp->s_ack_queue[qp->s_tail_ack_queue];
                ps->s_txreq->ss = &qp->s_ack_rdma_sge;
                delta = hfi1_build_tid_rdma_read_resp(qp, e, ohdr, &bth0,
                                                      &bth1, &bth2, &len,
                                                      &last_pkt);
                if (delta == 0)
                        goto error_qp;
                hwords += delta;
                if (last_pkt) {
                        e->sent = 1;
                        /*
                         * Increment qp->s_tail_ack_queue through s_ack_state
                         * transition.
                         */
                        qp->s_ack_state = OP(RDMA_READ_RESPONSE_LAST);
                }
                break;
        case TID_OP(READ_REQ):
                goto bail;

        default:
normal:
                /*
                 * Send a regular ACK.
                 * Set the s_ack_state so we wait until after sending
                 * the ACK before setting s_ack_state to ACKNOWLEDGE
                 * (see above).
                 */
                qp->s_ack_state = OP(SEND_ONLY);
normal_no_state:
                if (qp->s_nak_state)
                        ohdr->u.aeth =
                                cpu_to_be32((qp->r_msn & IB_MSN_MASK) |
                                            (qp->s_nak_state <<
                                             IB_AETH_CREDIT_SHIFT));
                else
                        ohdr->u.aeth = rvt_compute_aeth(qp);
                hwords++;
                len = 0;
                bth0 = OP(ACKNOWLEDGE) << 24;
                bth2 = mask_psn(qp->s_ack_psn);
                qp->s_flags &= ~RVT_S_ACK_PENDING;
                ps->s_txreq->txreq.flags |= SDMA_TXREQ_F_VIP;
                ps->s_txreq->ss = NULL;
        }
        qp->s_rdma_ack_cnt++;
        ps->s_txreq->sde = qpriv->s_sde;
        ps->s_txreq->s_cur_size = len;
        ps->s_txreq->hdr_dwords = hwords;
        hfi1_make_ruc_header(qp, ohdr, bth0, bth1, bth2, middle, ps);
        return 1;
error_qp:
        spin_unlock_irqrestore(&qp->s_lock, ps->flags);
        spin_lock_irqsave(&qp->r_lock, ps->flags);
        spin_lock(&qp->s_lock);
        rvt_error_qp(qp, IB_WC_WR_FLUSH_ERR);
        spin_unlock(&qp->s_lock);
        spin_unlock_irqrestore(&qp->r_lock, ps->flags);
        spin_lock_irqsave(&qp->s_lock, ps->flags);
bail:
        qp->s_ack_state = OP(ACKNOWLEDGE);
        /*
         * Ensure s_rdma_ack_cnt changes are committed prior to resetting
         * RVT_S_RESP_PENDING
         */
        smp_wmb();
        qp->s_flags &= ~(RVT_S_RESP_PENDING
                                | RVT_S_ACK_PENDING
                                | HFI1_S_AHG_VALID);
        return 0;
}

/**
 * hfi1_make_rc_req - construct a request packet (SEND, RDMA r/w, ATOMIC)
 * @qp: a pointer to the QP
 *
 * Assumes s_lock is held.
 *
 * Return 1 if constructed; otherwise, return 0.
 */
int hfi1_make_rc_req(struct rvt_qp *qp, struct hfi1_pkt_state *ps)
{
        struct hfi1_qp_priv *priv = qp->priv;
        struct hfi1_ibdev *dev = to_idev(qp->ibqp.device);
        struct ib_other_headers *ohdr;
        struct rvt_sge_state *ss = NULL;
        struct rvt_swqe *wqe;
        struct hfi1_swqe_priv *wpriv;
        struct tid_rdma_request *req = NULL;
        /* header size in 32-bit words LRH+BTH = (8+12)/4. */
        u32 hwords = 5;
        u32 len = 0;
        u32 bth0 = 0, bth2 = 0;
        u32 bth1 = qp->remote_qpn | (HFI1_CAP_IS_KSET(OPFN) << IB_BTHE_E_SHIFT);
        u32 pmtu = qp->pmtu;
        char newreq;
        int middle = 0;
        int delta;
        struct tid_rdma_flow *flow = NULL;
        struct tid_rdma_params *remote;

        trace_hfi1_sender_make_rc_req(qp);
        lockdep_assert_held(&qp->s_lock);
        ps->s_txreq = get_txreq(ps->dev, qp);
        if (!ps->s_txreq)
                goto bail_no_tx;

        if (priv->hdr_type == HFI1_PKT_TYPE_9B) {
                /* header size in 32-bit words LRH+BTH = (8+12)/4. */
                hwords = 5;
                if (rdma_ah_get_ah_flags(&qp->remote_ah_attr) & IB_AH_GRH)
                        ohdr = &ps->s_txreq->phdr.hdr.ibh.u.l.oth;
                else
                        ohdr = &ps->s_txreq->phdr.hdr.ibh.u.oth;
        } else {
                /* header size in 32-bit words 16B LRH+BTH = (16+12)/4. */
                hwords = 7;
                if ((rdma_ah_get_ah_flags(&qp->remote_ah_attr) & IB_AH_GRH) &&
                    (hfi1_check_mcast(rdma_ah_get_dlid(&qp->remote_ah_attr))))
                        ohdr = &ps->s_txreq->phdr.hdr.opah.u.l.oth;
                else
                        ohdr = &ps->s_txreq->phdr.hdr.opah.u.oth;
        }

        /* Sending responses has higher priority over sending requests. */
        if ((qp->s_flags & RVT_S_RESP_PENDING) &&
            make_rc_ack(dev, qp, ohdr, ps))
                return 1;

        if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_SEND_OK)) {
                if (!(ib_rvt_state_ops[qp->state] & RVT_FLUSH_SEND))
                        goto bail;
                /* We are in the error state, flush the work request. */
                if (qp->s_last == READ_ONCE(qp->s_head))
                        goto bail;
                /* If DMAs are in progress, we can't flush immediately. */
                if (iowait_sdma_pending(&priv->s_iowait)) {
                        qp->s_flags |= RVT_S_WAIT_DMA;
                        goto bail;
                }
                clear_ahg(qp);
                wqe = rvt_get_swqe_ptr(qp, qp->s_last);
                hfi1_trdma_send_complete(qp, wqe, qp->s_last != qp->s_acked ?
                                         IB_WC_SUCCESS : IB_WC_WR_FLUSH_ERR);
                /* will get called again */
                goto done_free_tx;
        }

        if (qp->s_flags & (RVT_S_WAIT_RNR | RVT_S_WAIT_ACK | HFI1_S_WAIT_HALT))
                goto bail;

        if (cmp_psn(qp->s_psn, qp->s_sending_hpsn) <= 0) {
                if (cmp_psn(qp->s_sending_psn, qp->s_sending_hpsn) <= 0) {
                        qp->s_flags |= RVT_S_WAIT_PSN;
                        goto bail;
                }
                qp->s_sending_psn = qp->s_psn;
                qp->s_sending_hpsn = qp->s_psn - 1;
        }

        /* Send a request. */
        wqe = rvt_get_swqe_ptr(qp, qp->s_cur);
check_s_state:
        switch (qp->s_state) {
        default:
                if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_NEXT_SEND_OK))
                        goto bail;
                /*
                 * Resend an old request or start a new one.
                 *
                 * We keep track of the current SWQE so that
                 * we don't reset the "furthest progress" state
                 * if we need to back up.
                 */
                newreq = 0;
                if (qp->s_cur == qp->s_tail) {
                        /* Check if send work queue is empty. */
                        if (qp->s_tail == READ_ONCE(qp->s_head)) {
                                clear_ahg(qp);
                                goto bail;
                        }
                        /*
                         * If a fence is requested, wait for previous
                         * RDMA read and atomic operations to finish.
                         * However, there is no need to guard against
                         * TID RDMA READ after TID RDMA READ.
                         */
                        if ((wqe->wr.send_flags & IB_SEND_FENCE) &&
                            qp->s_num_rd_atomic &&
                            (wqe->wr.opcode != IB_WR_TID_RDMA_READ ||
                             priv->pending_tid_r_segs < qp->s_num_rd_atomic)) {
                                qp->s_flags |= RVT_S_WAIT_FENCE;
                                goto bail;
                        }
                        /*
                         * Local operations are processed immediately
                         * after all prior requests have completed
                         */
                        if (wqe->wr.opcode == IB_WR_REG_MR ||
                            wqe->wr.opcode == IB_WR_LOCAL_INV) {
                                int local_ops = 0;
                                int err = 0;

                                if (qp->s_last != qp->s_cur)
                                        goto bail;
                                if (++qp->s_cur == qp->s_size)
                                        qp->s_cur = 0;
                                if (++qp->s_tail == qp->s_size)
                                        qp->s_tail = 0;
                                if (!(wqe->wr.send_flags &
                                      RVT_SEND_COMPLETION_ONLY)) {
                                        err = rvt_invalidate_rkey(
                                                qp,
                                                wqe->wr.ex.invalidate_rkey);
                                        local_ops = 1;
                                }
                                rvt_send_complete(qp, wqe,
                                                  err ? IB_WC_LOC_PROT_ERR
                                                      : IB_WC_SUCCESS);
                                if (local_ops)
                                        atomic_dec(&qp->local_ops_pending);
                                goto done_free_tx;
                        }

                        newreq = 1;
                        qp->s_psn = wqe->psn;
                }
                /*
                 * Note that we have to be careful not to modify the
                 * original work request since we may need to resend
                 * it.
                 */
                len = wqe->length;
                ss = &qp->s_sge;
                bth2 = mask_psn(qp->s_psn);

                /*
                 * Interlock between various IB requests and TID RDMA
                 * if necessary.
                 */
                if ((priv->s_flags & HFI1_S_TID_WAIT_INTERLCK) ||
                    hfi1_tid_rdma_wqe_interlock(qp, wqe))
                        goto bail;

                switch (wqe->wr.opcode) {
                case IB_WR_SEND:
                case IB_WR_SEND_WITH_IMM:
                case IB_WR_SEND_WITH_INV:
                        /* If no credit, return. */
                        if (!(qp->s_flags & RVT_S_UNLIMITED_CREDIT) &&
                            rvt_cmp_msn(wqe->ssn, qp->s_lsn + 1) > 0) {
                                qp->s_flags |= RVT_S_WAIT_SSN_CREDIT;
                                goto bail;
                        }
                        if (len > pmtu) {
                                qp->s_state = OP(SEND_FIRST);
                                len = pmtu;
                                break;
                        }
                        if (wqe->wr.opcode == IB_WR_SEND) {
                                qp->s_state = OP(SEND_ONLY);
                        } else if (wqe->wr.opcode == IB_WR_SEND_WITH_IMM) {
                                qp->s_state = OP(SEND_ONLY_WITH_IMMEDIATE);
                                /* Immediate data comes after the BTH */
                                ohdr->u.imm_data = wqe->wr.ex.imm_data;
                                hwords += 1;
                        } else {
                                qp->s_state = OP(SEND_ONLY_WITH_INVALIDATE);
                                /* Invalidate rkey comes after the BTH */
                                ohdr->u.ieth = cpu_to_be32(
                                                wqe->wr.ex.invalidate_rkey);
                                hwords += 1;
                        }
                        if (wqe->wr.send_flags & IB_SEND_SOLICITED)
                                bth0 |= IB_BTH_SOLICITED;
                        bth2 |= IB_BTH_REQ_ACK;
                        if (++qp->s_cur == qp->s_size)
                                qp->s_cur = 0;
                        break;

                case IB_WR_RDMA_WRITE:
                        if (newreq && !(qp->s_flags & RVT_S_UNLIMITED_CREDIT))
                                qp->s_lsn++;
                        goto no_flow_control;
                case IB_WR_RDMA_WRITE_WITH_IMM:
                        /* If no credit, return. */
                        if (!(qp->s_flags & RVT_S_UNLIMITED_CREDIT) &&
                            rvt_cmp_msn(wqe->ssn, qp->s_lsn + 1) > 0) {
                                qp->s_flags |= RVT_S_WAIT_SSN_CREDIT;
                                goto bail;
                        }
no_flow_control:
                        put_ib_reth_vaddr(
                                wqe->rdma_wr.remote_addr,
                                &ohdr->u.rc.reth);
                        ohdr->u.rc.reth.rkey =
                                cpu_to_be32(wqe->rdma_wr.rkey);
                        ohdr->u.rc.reth.length = cpu_to_be32(len);
                        hwords += sizeof(struct ib_reth) / sizeof(u32);
                        if (len > pmtu) {
                                qp->s_state = OP(RDMA_WRITE_FIRST);
                                len = pmtu;
                                break;
                        }
                        if (wqe->wr.opcode == IB_WR_RDMA_WRITE) {
                                qp->s_state = OP(RDMA_WRITE_ONLY);
                        } else {
                                qp->s_state =
                                        OP(RDMA_WRITE_ONLY_WITH_IMMEDIATE);
                                /* Immediate data comes after RETH */
                                ohdr->u.rc.imm_data = wqe->wr.ex.imm_data;
                                hwords += 1;
                                if (wqe->wr.send_flags & IB_SEND_SOLICITED)
                                        bth0 |= IB_BTH_SOLICITED;
                        }
                        bth2 |= IB_BTH_REQ_ACK;
                        if (++qp->s_cur == qp->s_size)
                                qp->s_cur = 0;
                        break;

                case IB_WR_TID_RDMA_WRITE:
                        if (newreq) {
                                /*
                                 * Limit the number of TID RDMA WRITE requests.
                                 */
                                if (atomic_read(&priv->n_tid_requests) >=
                                    HFI1_TID_RDMA_WRITE_CNT)
                                        goto bail;

                                if (!(qp->s_flags & RVT_S_UNLIMITED_CREDIT))
                                        qp->s_lsn++;
                        }

                        hwords += hfi1_build_tid_rdma_write_req(qp, wqe, ohdr,
                                                                &bth1, &bth2,
                                                                &len);
                        ss = NULL;
                        if (priv->s_tid_cur == HFI1_QP_WQE_INVALID) {
                                priv->s_tid_cur = qp->s_cur;
                                if (priv->s_tid_tail == HFI1_QP_WQE_INVALID) {
                                        priv->s_tid_tail = qp->s_cur;
                                        priv->s_state = TID_OP(WRITE_RESP);
                                }
                        } else if (priv->s_tid_cur == priv->s_tid_head) {
                                struct rvt_swqe *__w;
                                struct tid_rdma_request *__r;

                                __w = rvt_get_swqe_ptr(qp, priv->s_tid_cur);
                                __r = wqe_to_tid_req(__w);

                                /*
                                 * The s_tid_cur pointer is advanced to s_cur if
                                 * any of the following conditions about the WQE
                                 * to which s_ti_cur currently points to are
                                 * satisfied:
                                 *   1. The request is not a TID RDMA WRITE
                                 *      request,
                                 *   2. The request is in the INACTIVE or
                                 *      COMPLETE states (TID RDMA READ requests
                                 *      stay at INACTIVE and TID RDMA WRITE
                                 *      transition to COMPLETE when done),
                                 *   3. The request is in the ACTIVE or SYNC
                                 *      state and the number of completed
                                 *      segments is equal to the total segment
                                 *      count.
                                 *      (If ACTIVE, the request is waiting for
                                 *       ACKs. If SYNC, the request has not
                                 *       received any responses because it's
                                 *       waiting on a sync point.)
                                 */
                                if (__w->wr.opcode != IB_WR_TID_RDMA_WRITE ||
                                    __r->state == TID_REQUEST_INACTIVE ||
                                    __r->state == TID_REQUEST_COMPLETE ||
                                    ((__r->state == TID_REQUEST_ACTIVE ||
                                      __r->state == TID_REQUEST_SYNC) &&
                                     __r->comp_seg == __r->total_segs)) {
                                        if (priv->s_tid_tail ==
                                            priv->s_tid_cur &&
                                            priv->s_state ==
                                            TID_OP(WRITE_DATA_LAST)) {
                                                priv->s_tid_tail = qp->s_cur;
                                                priv->s_state =
                                                        TID_OP(WRITE_RESP);
                                        }
                                        priv->s_tid_cur = qp->s_cur;
                                }
                                /*
                                 * A corner case: when the last TID RDMA WRITE
                                 * request was completed, s_tid_head,
                                 * s_tid_cur, and s_tid_tail all point to the
                                 * same location. Other requests are posted and
                                 * s_cur wraps around to the same location,
                                 * where a new TID RDMA WRITE is posted. In
                                 * this case, none of the indices need to be
                                 * updated. However, the priv->s_state should.
                                 */
                                if (priv->s_tid_tail == qp->s_cur &&
                                    priv->s_state == TID_OP(WRITE_DATA_LAST))
                                        priv->s_state = TID_OP(WRITE_RESP);
                        }
                        req = wqe_to_tid_req(wqe);
                        if (newreq) {
                                priv->s_tid_head = qp->s_cur;
                                priv->pending_tid_w_resp += req->total_segs;
                                atomic_inc(&priv->n_tid_requests);
                                atomic_dec(&priv->n_requests);
                        } else {
                                req->state = TID_REQUEST_RESEND;
                                req->comp_seg = delta_psn(bth2, wqe->psn);
                                /*
                                 * Pull back any segments since we are going
                                 * to re-receive them.
                                 */
                                req->setup_head = req->clear_tail;
                                priv->pending_tid_w_resp +=
                                        delta_psn(wqe->lpsn, bth2) + 1;
                        }

                        trace_hfi1_tid_write_sender_make_req(qp, newreq);
                        trace_hfi1_tid_req_make_req_write(qp, newreq,
                                                          wqe->wr.opcode,
                                                          wqe->psn, wqe->lpsn,
                                                          req);
                        if (++qp->s_cur == qp->s_size)
                                qp->s_cur = 0;
                        break;

                case IB_WR_RDMA_READ:
                        /*
                         * Don't allow more operations to be started
                         * than the QP limits allow.
                         */
                        if (qp->s_num_rd_atomic >=
                            qp->s_max_rd_atomic) {
                                qp->s_flags |= RVT_S_WAIT_RDMAR;
                                goto bail;
                        }
                        qp->s_num_rd_atomic++;
                        if (newreq && !(qp->s_flags & RVT_S_UNLIMITED_CREDIT))
                                qp->s_lsn++;
                        put_ib_reth_vaddr(
                                wqe->rdma_wr.remote_addr,
                                &ohdr->u.rc.reth);
                        ohdr->u.rc.reth.rkey =
                                cpu_to_be32(wqe->rdma_wr.rkey);
                        ohdr->u.rc.reth.length = cpu_to_be32(len);
                        qp->s_state = OP(RDMA_READ_REQUEST);
                        hwords += sizeof(ohdr->u.rc.reth) / sizeof(u32);
                        ss = NULL;
                        len = 0;
                        bth2 |= IB_BTH_REQ_ACK;
                        if (++qp->s_cur == qp->s_size)
                                qp->s_cur = 0;
                        break;

                case IB_WR_TID_RDMA_READ:
                        trace_hfi1_tid_read_sender_make_req(qp, newreq);
                        wpriv = wqe->priv;
                        req = wqe_to_tid_req(wqe);
                        trace_hfi1_tid_req_make_req_read(qp, newreq,
                                                         wqe->wr.opcode,
                                                         wqe->psn, wqe->lpsn,
                                                         req);
                        delta = cmp_psn(qp->s_psn, wqe->psn);

                        /*
                         * Don't allow more operations to be started
                         * than the QP limits allow. We could get here under
                         * three conditions; (1) It's a new request; (2) We are
                         * sending the second or later segment of a request,
                         * but the qp->s_state is set to OP(RDMA_READ_REQUEST)
                         * when the last segment of a previous request is
                         * received just before this; (3) We are re-sending a
                         * request.
                         */
                        if (qp->s_num_rd_atomic >= qp->s_max_rd_atomic) {
                                qp->s_flags |= RVT_S_WAIT_RDMAR;
                                goto bail;
                        }
                        if (newreq) {
                                struct tid_rdma_flow *flow =
                                        &req->flows[req->setup_head];

                                /*
                                 * Set up s_sge as it is needed for TID
                                 * allocation. However, if the pages have been
                                 * walked and mapped, skip it. An earlier try
                                 * has failed to allocate the TID entries.
                                 */
                                if (!flow->npagesets) {
                                        qp->s_sge.sge = wqe->sg_list[0];
                                        qp->s_sge.sg_list = wqe->sg_list + 1;
                                        qp->s_sge.num_sge = wqe->wr.num_sge;
                                        qp->s_sge.total_len = wqe->length;
                                        qp->s_len = wqe->length;
                                        req->isge = 0;
                                        req->clear_tail = req->setup_head;
                                        req->flow_idx = req->setup_head;
                                        req->state = TID_REQUEST_ACTIVE;
                                }
                        } else if (delta == 0) {
                                /* Re-send a request */
                                req->cur_seg = 0;
                                req->comp_seg = 0;
                                req->ack_pending = 0;
                                req->flow_idx = req->clear_tail;
                                req->state = TID_REQUEST_RESEND;
                        }
                        req->s_next_psn = qp->s_psn;
                        /* Read one segment at a time */
                        len = min_t(u32, req->seg_len,
                                    wqe->length - req->seg_len * req->cur_seg);
                        delta = hfi1_build_tid_rdma_read_req(qp, wqe, ohdr,
                                                             &bth1, &bth2,
                                                             &len);
                        if (delta <= 0) {
                                /* Wait for TID space */
                                goto bail;
                        }
                        if (newreq && !(qp->s_flags & RVT_S_UNLIMITED_CREDIT))
                                qp->s_lsn++;
                        hwords += delta;
                        ss = &wpriv->ss;
                        /* Check if this is the last segment */
                        if (req->cur_seg >= req->total_segs &&
                            ++qp->s_cur == qp->s_size)
                                qp->s_cur = 0;
                        break;

                case IB_WR_ATOMIC_CMP_AND_SWP:
                case IB_WR_ATOMIC_FETCH_AND_ADD:
                        /*
                         * Don't allow more operations to be started
                         * than the QP limits allow.
                         */
                        if (qp->s_num_rd_atomic >=
                            qp->s_max_rd_atomic) {
                                qp->s_flags |= RVT_S_WAIT_RDMAR;
                                goto bail;
                        }
                        qp->s_num_rd_atomic++;

                        /* FALLTHROUGH */
                case IB_WR_OPFN:
                        if (newreq && !(qp->s_flags & RVT_S_UNLIMITED_CREDIT))
                                qp->s_lsn++;
                        if (wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP ||
                            wqe->wr.opcode == IB_WR_OPFN) {
                                qp->s_state = OP(COMPARE_SWAP);
                                put_ib_ateth_swap(wqe->atomic_wr.swap,
                                                  &ohdr->u.atomic_eth);
                                put_ib_ateth_compare(wqe->atomic_wr.compare_add,
                                                     &ohdr->u.atomic_eth);
                        } else {
                                qp->s_state = OP(FETCH_ADD);
                                put_ib_ateth_swap(wqe->atomic_wr.compare_add,
                                                  &ohdr->u.atomic_eth);
                                put_ib_ateth_compare(0, &ohdr->u.atomic_eth);
                        }
                        put_ib_ateth_vaddr(wqe->atomic_wr.remote_addr,
                                           &ohdr->u.atomic_eth);
                        ohdr->u.atomic_eth.rkey = cpu_to_be32(
                                wqe->atomic_wr.rkey);
                        hwords += sizeof(struct ib_atomic_eth) / sizeof(u32);
                        ss = NULL;
                        len = 0;
                        bth2 |= IB_BTH_REQ_ACK;
                        if (++qp->s_cur == qp->s_size)
                                qp->s_cur = 0;
                        break;

                default:
                        goto bail;
                }
                if (wqe->wr.opcode != IB_WR_TID_RDMA_READ) {
                        qp->s_sge.sge = wqe->sg_list[0];
                        qp->s_sge.sg_list = wqe->sg_list + 1;
                        qp->s_sge.num_sge = wqe->wr.num_sge;
                        qp->s_sge.total_len = wqe->length;
                        qp->s_len = wqe->length;
                }
                if (newreq) {
                        qp->s_tail++;
                        if (qp->s_tail >= qp->s_size)
                                qp->s_tail = 0;
                }
                if (wqe->wr.opcode == IB_WR_RDMA_READ ||
                    wqe->wr.opcode == IB_WR_TID_RDMA_WRITE)
                        qp->s_psn = wqe->lpsn + 1;
                else if (wqe->wr.opcode == IB_WR_TID_RDMA_READ)
                        qp->s_psn = req->s_next_psn;
                else
                        qp->s_psn++;
                break;

        case OP(RDMA_READ_RESPONSE_FIRST):
                /*
                 * qp->s_state is normally set to the opcode of the
                 * last packet constructed for new requests and therefore
                 * is never set to RDMA read response.
                 * RDMA_READ_RESPONSE_FIRST is used by the ACK processing
                 * thread to indicate a SEND needs to be restarted from an
                 * earlier PSN without interfering with the sending thread.
                 * See restart_rc().
                 */
                qp->s_len = restart_sge(&qp->s_sge, wqe, qp->s_psn, pmtu);
                /* FALLTHROUGH */
        case OP(SEND_FIRST):
                qp->s_state = OP(SEND_MIDDLE);
                /* FALLTHROUGH */
        case OP(SEND_MIDDLE):
                bth2 = mask_psn(qp->s_psn++);
                ss = &qp->s_sge;
                len = qp->s_len;
                if (len > pmtu) {
                        len = pmtu;
                        middle = HFI1_CAP_IS_KSET(SDMA_AHG);
                        break;
                }
                if (wqe->wr.opcode == IB_WR_SEND) {
                        qp->s_state = OP(SEND_LAST);
                } else if (wqe->wr.opcode == IB_WR_SEND_WITH_IMM) {
                        qp->s_state = OP(SEND_LAST_WITH_IMMEDIATE);
                        /* Immediate data comes after the BTH */
                        ohdr->u.imm_data = wqe->wr.ex.imm_data;
                        hwords += 1;
                } else {
                        qp->s_state = OP(SEND_LAST_WITH_INVALIDATE);
                        /* invalidate data comes after the BTH */
                        ohdr->u.ieth = cpu_to_be32(wqe->wr.ex.invalidate_rkey);
                        hwords += 1;
                }
                if (wqe->wr.send_flags & IB_SEND_SOLICITED)
                        bth0 |= IB_BTH_SOLICITED;
                bth2 |= IB_BTH_REQ_ACK;
                qp->s_cur++;
                if (qp->s_cur >= qp->s_size)
                        qp->s_cur = 0;
                break;

        case OP(RDMA_READ_RESPONSE_LAST):
                /*
                 * qp->s_state is normally set to the opcode of the
                 * last packet constructed for new requests and therefore
                 * is never set to RDMA read response.
                 * RDMA_READ_RESPONSE_LAST is used by the ACK processing
                 * thread to indicate a RDMA write needs to be restarted from
                 * an earlier PSN without interfering with the sending thread.
                 * See restart_rc().
                 */
                qp->s_len = restart_sge(&qp->s_sge, wqe, qp->s_psn, pmtu);
                /* FALLTHROUGH */

        case OP(RDMA_WRITE_FIRST):
                qp->s_state = OP(RDMA_WRITE_MIDDLE);
                /* FALLTHROUGH */
        case OP(RDMA_WRITE_MIDDLE):
                bth2 = mask_psn(qp->s_psn++);
                ss = &qp->s_sge;
                len = qp->s_len;
                if (len > pmtu) {
                        len = pmtu;
                        middle = HFI1_CAP_IS_KSET(SDMA_AHG);
                        break;
                }
                if (wqe->wr.opcode == IB_WR_RDMA_WRITE) {
                        qp->s_state = OP(RDMA_WRITE_LAST);
                } else {
                        qp->s_state = OP(RDMA_WRITE_LAST_WITH_IMMEDIATE);
                        /* Immediate data comes after the BTH */
                        ohdr->u.imm_data = wqe->wr.ex.imm_data;
                        hwords += 1;
                        if (wqe->wr.send_flags & IB_SEND_SOLICITED)
                                bth0 |= IB_BTH_SOLICITED;
                }
                bth2 |= IB_BTH_REQ_ACK;
                qp->s_cur++;
                if (qp->s_cur >= qp->s_size)
                        qp->s_cur = 0;
                break;

        case OP(RDMA_READ_RESPONSE_MIDDLE):
                /*
                 * qp->s_state is normally set to the opcode of the
                 * last packet constructed for new requests and therefore
                 * is never set to RDMA read response.
                 * RDMA_READ_RESPONSE_MIDDLE is used by the ACK processing
                 * thread to indicate a RDMA read needs to be restarted from
                 * an earlier PSN without interfering with the sending thread.
                 * See restart_rc().
                 */
                len = (delta_psn(qp->s_psn, wqe->psn)) * pmtu;
                put_ib_reth_vaddr(
                        wqe->rdma_wr.remote_addr + len,
                        &ohdr->u.rc.reth);
                ohdr->u.rc.reth.rkey =
                        cpu_to_be32(wqe->rdma_wr.rkey);
                ohdr->u.rc.reth.length = cpu_to_be32(wqe->length - len);
                qp->s_state = OP(RDMA_READ_REQUEST);
                hwords += sizeof(ohdr->u.rc.reth) / sizeof(u32);
                bth2 = mask_psn(qp->s_psn) | IB_BTH_REQ_ACK;
                qp->s_psn = wqe->lpsn + 1;
                ss = NULL;
                len = 0;
                qp->s_cur++;
                if (qp->s_cur == qp->s_size)
                        qp->s_cur = 0;
                break;

        case TID_OP(WRITE_RESP):
                /*
                 * This value for s_state is used for restarting a TID RDMA
                 * WRITE request. See comment in OP(RDMA_READ_RESPONSE_MIDDLE
                 * for more).
                 */
                req = wqe_to_tid_req(wqe);
                req->state = TID_REQUEST_RESEND;
                rcu_read_lock();
                remote = rcu_dereference(priv->tid_rdma.remote);
                req->comp_seg = delta_psn(qp->s_psn, wqe->psn);
                len = wqe->length - (req->comp_seg * remote->max_len);
                rcu_read_unlock();

                bth2 = mask_psn(qp->s_psn);
                hwords += hfi1_build_tid_rdma_write_req(qp, wqe, ohdr, &bth1,
                                                        &bth2, &len);
                qp->s_psn = wqe->lpsn + 1;
                ss = NULL;
                qp->s_state = TID_OP(WRITE_REQ);
                priv->pending_tid_w_resp += delta_psn(wqe->lpsn, bth2) + 1;
                priv->s_tid_cur = qp->s_cur;
                if (++qp->s_cur == qp->s_size)
                        qp->s_cur = 0;
                trace_hfi1_tid_req_make_req_write(qp, 0, wqe->wr.opcode,
                                                  wqe->psn, wqe->lpsn, req);
                break;

        case TID_OP(READ_RESP):
                if (wqe->wr.opcode != IB_WR_TID_RDMA_READ)
                        goto bail;
                /* This is used to restart a TID read request */
                req = wqe_to_tid_req(wqe);
                wpriv = wqe->priv;
                /*
                 * Back down. The field qp->s_psn has been set to the psn with
                 * which the request should be restart. It's OK to use division
                 * as this is on the retry path.
                 */
                req->cur_seg = delta_psn(qp->s_psn, wqe->psn) / priv->pkts_ps;

                /*
                 * The following function need to be redefined to return the
                 * status to make sure that we find the flow. At the same
                 * time, we can use the req->state change to check if the
                 * call succeeds or not.
                 */
                req->state = TID_REQUEST_RESEND;
                hfi1_tid_rdma_restart_req(qp, wqe, &bth2);
                if (req->state != TID_REQUEST_ACTIVE) {
                        /*
                         * Failed to find the flow. Release all allocated tid
                         * resources.
                         */
                        hfi1_kern_exp_rcv_clear_all(req);
                        hfi1_kern_clear_hw_flow(priv->rcd, qp);

                        hfi1_trdma_send_complete(qp, wqe, IB_WC_LOC_QP_OP_ERR);
                        goto bail;
                }
                req->state = TID_REQUEST_RESEND;
                len = min_t(u32, req->seg_len,
                            wqe->length - req->seg_len * req->cur_seg);
                flow = &req->flows[req->flow_idx];
                len -= flow->sent;
                req->s_next_psn = flow->flow_state.ib_lpsn + 1;
                delta = hfi1_build_tid_rdma_read_packet(wqe, ohdr, &bth1,
                                                        &bth2, &len);
                if (delta <= 0) {
                        /* Wait for TID space */
                        goto bail;
                }
                hwords += delta;
                ss = &wpriv->ss;
                /* Check if this is the last segment */
                if (req->cur_seg >= req->total_segs &&
                    ++qp->s_cur == qp->s_size)
                        qp->s_cur = 0;
                qp->s_psn = req->s_next_psn;
                trace_hfi1_tid_req_make_req_read(qp, 0, wqe->wr.opcode,
                                                 wqe->psn, wqe->lpsn, req);
                break;
        case TID_OP(READ_REQ):
                req = wqe_to_tid_req(wqe);
                delta = cmp_psn(qp->s_psn, wqe->psn);
                /*
                 * If the current WR is not TID RDMA READ, or this is the start
                 * of a new request, we need to change the qp->s_state so that
                 * the request can be set up properly.
                 */
                if (wqe->wr.opcode != IB_WR_TID_RDMA_READ || delta == 0 ||
                    qp->s_cur == qp->s_tail) {
                        qp->s_state = OP(RDMA_READ_REQUEST);
                        if (delta == 0 || qp->s_cur == qp->s_tail)
                                goto check_s_state;
                        else
                                goto bail;
                }

                /* Rate limiting */
                if (qp->s_num_rd_atomic >= qp->s_max_rd_atomic) {
                        qp->s_flags |= RVT_S_WAIT_RDMAR;
                        goto bail;
                }

                wpriv = wqe->priv;
                /* Read one segment at a time */
                len = min_t(u32, req->seg_len,
                            wqe->length - req->seg_len * req->cur_seg);
                delta = hfi1_build_tid_rdma_read_req(qp, wqe, ohdr, &bth1,
                                                     &bth2, &len);
                if (delta <= 0) {
                        /* Wait for TID space */
                        goto bail;
                }
                hwords += delta;
                ss = &wpriv->ss;
                /* Check if this is the last segment */
                if (req->cur_seg >= req->total_segs &&
                    ++qp->s_cur == qp->s_size)
                        qp->s_cur = 0;
                qp->s_psn = req->s_next_psn;
                trace_hfi1_tid_req_make_req_read(qp, 0, wqe->wr.opcode,
                                                 wqe->psn, wqe->lpsn, req);
                break;
        }
        qp->s_sending_hpsn = bth2;
        delta = delta_psn(bth2, wqe->psn);
        if (delta && delta % HFI1_PSN_CREDIT == 0 &&
            wqe->wr.opcode != IB_WR_TID_RDMA_WRITE)
                bth2 |= IB_BTH_REQ_ACK;
        if (qp->s_flags & RVT_S_SEND_ONE) {
                qp->s_flags &= ~RVT_S_SEND_ONE;
                qp->s_flags |= RVT_S_WAIT_ACK;
                bth2 |= IB_BTH_REQ_ACK;
        }
        qp->s_len -= len;
        ps->s_txreq->hdr_dwords = hwords;
        ps->s_txreq->sde = priv->s_sde;
        ps->s_txreq->ss = ss;
        ps->s_txreq->s_cur_size = len;
        hfi1_make_ruc_header(
                qp,
                ohdr,
                bth0 | (qp->s_state << 24),
                bth1,
                bth2,
                middle,
                ps);
        return 1;

done_free_tx:
        hfi1_put_txreq(ps->s_txreq);
        ps->s_txreq = NULL;
        return 1;

bail:
        hfi1_put_txreq(ps->s_txreq);

bail_no_tx:
        ps->s_txreq = NULL;
        qp->s_flags &= ~RVT_S_BUSY;
        /*
         * If we didn't get a txreq, the QP will be woken up later to try
         * again. Set the flags to indicate which work item to wake
         * up.
         */
        iowait_set_flag(&priv->s_iowait, IOWAIT_PENDING_IB);
        return 0;
}

static inline void hfi1_make_bth_aeth(struct rvt_qp *qp,
                                      struct ib_other_headers *ohdr,
                                      u32 bth0, u32 bth1)
{
        if (qp->r_nak_state)
                ohdr->u.aeth = cpu_to_be32((qp->r_msn & IB_MSN_MASK) |
                                            (qp->r_nak_state <<
                                             IB_AETH_CREDIT_SHIFT));
        else
                ohdr->u.aeth = rvt_compute_aeth(qp);

        ohdr->bth[0] = cpu_to_be32(bth0);
        ohdr->bth[1] = cpu_to_be32(bth1 | qp->remote_qpn);
        ohdr->bth[2] = cpu_to_be32(mask_psn(qp->r_ack_psn));
}

static inline void hfi1_queue_rc_ack(struct hfi1_packet *packet, bool is_fecn)
{
        struct rvt_qp *qp = packet->qp;
        struct hfi1_ibport *ibp;
        unsigned long flags;

        spin_lock_irqsave(&qp->s_lock, flags);
        if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK))
                goto unlock;
        ibp = rcd_to_iport(packet->rcd);
        this_cpu_inc(*ibp->rvp.rc_qacks);
        qp->s_flags |= RVT_S_ACK_PENDING | RVT_S_RESP_PENDING;
        qp->s_nak_state = qp->r_nak_state;
        qp->s_ack_psn = qp->r_ack_psn;
        if (is_fecn)
                qp->s_flags |= RVT_S_ECN;

        /* Schedule the send tasklet. */
        hfi1_schedule_send(qp);
unlock:
        spin_unlock_irqrestore(&qp->s_lock, flags);
}

static inline void hfi1_make_rc_ack_9B(struct hfi1_packet *packet,
                                       struct hfi1_opa_header *opa_hdr,
                                       u8 sc5, bool is_fecn,
                                       u64 *pbc_flags, u32 *hwords,
                                       u32 *nwords)
{
        struct rvt_qp *qp = packet->qp;
        struct hfi1_ibport *ibp = rcd_to_iport(packet->rcd);
        struct hfi1_pportdata *ppd = ppd_from_ibp(ibp);
        struct ib_header *hdr = &opa_hdr->ibh;
        struct ib_other_headers *ohdr;
        u16 lrh0 = HFI1_LRH_BTH;
        u16 pkey;
        u32 bth0, bth1;

        opa_hdr->hdr_type = HFI1_PKT_TYPE_9B;
        ohdr = &hdr->u.oth;
        /* header size in 32-bit words LRH+BTH+AETH = (8+12+4)/4 */
        *hwords = 6;

        if (unlikely(rdma_ah_get_ah_flags(&qp->remote_ah_attr) & IB_AH_GRH)) {
                *hwords += hfi1_make_grh(ibp, &hdr->u.l.grh,
                                         rdma_ah_read_grh(&qp->remote_ah_attr),
                                         *hwords - 2, SIZE_OF_CRC);
                ohdr = &hdr->u.l.oth;
                lrh0 = HFI1_LRH_GRH;
        }
        /* set PBC_DC_INFO bit (aka SC[4]) in pbc_flags */
        *pbc_flags |= ((!!(sc5 & 0x10)) << PBC_DC_INFO_SHIFT);

        /* read pkey_index w/o lock (its atomic) */
        pkey = hfi1_get_pkey(ibp, qp->s_pkey_index);

        lrh0 |= (sc5 & IB_SC_MASK) << IB_SC_SHIFT |
                (rdma_ah_get_sl(&qp->remote_ah_attr) & IB_SL_MASK) <<
                        IB_SL_SHIFT;

        hfi1_make_ib_hdr(hdr, lrh0, *hwords + SIZE_OF_CRC,
                         opa_get_lid(rdma_ah_get_dlid(&qp->remote_ah_attr), 9B),
                         ppd->lid | rdma_ah_get_path_bits(&qp->remote_ah_attr));

        bth0 = pkey | (OP(ACKNOWLEDGE) << 24);
        if (qp->s_mig_state == IB_MIG_MIGRATED)
                bth0 |= IB_BTH_MIG_REQ;
        bth1 = (!!is_fecn) << IB_BECN_SHIFT;
        /*
         * Inline ACKs go out without the use of the Verbs send engine, so
         * we need to set the STL Verbs Extended bit here
         */
        bth1 |= HFI1_CAP_IS_KSET(OPFN) << IB_BTHE_E_SHIFT;
        hfi1_make_bth_aeth(qp, ohdr, bth0, bth1);
}

static inline void hfi1_make_rc_ack_16B(struct hfi1_packet *packet,
                                        struct hfi1_opa_header *opa_hdr,
                                        u8 sc5, bool is_fecn,
                                        u64 *pbc_flags, u32 *hwords,
                                        u32 *nwords)
{
        struct rvt_qp *qp = packet->qp;
        struct hfi1_ibport *ibp = rcd_to_iport(packet->rcd);
        struct hfi1_pportdata *ppd = ppd_from_ibp(ibp);
        struct hfi1_16b_header *hdr = &opa_hdr->opah;
        struct ib_other_headers *ohdr;
        u32 bth0, bth1 = 0;
        u16 len, pkey;
        bool becn = is_fecn;
        u8 l4 = OPA_16B_L4_IB_LOCAL;
        u8 extra_bytes;

        opa_hdr->hdr_type = HFI1_PKT_TYPE_16B;
        ohdr = &hdr->u.oth;
        /* header size in 32-bit words 16B LRH+BTH+AETH = (16+12+4)/4 */
        *hwords = 8;
        extra_bytes = hfi1_get_16b_padding(*hwords << 2, 0);
        *nwords = SIZE_OF_CRC + ((extra_bytes + SIZE_OF_LT) >> 2);

        if (unlikely(rdma_ah_get_ah_flags(&qp->remote_ah_attr) & IB_AH_GRH) &&
            hfi1_check_mcast(rdma_ah_get_dlid(&qp->remote_ah_attr))) {
                *hwords += hfi1_make_grh(ibp, &hdr->u.l.grh,
                                         rdma_ah_read_grh(&qp->remote_ah_attr),
                                         *hwords - 4, *nwords);
                ohdr = &hdr->u.l.oth;
                l4 = OPA_16B_L4_IB_GLOBAL;
        }
        *pbc_flags |= PBC_PACKET_BYPASS | PBC_INSERT_BYPASS_ICRC;

        /* read pkey_index w/o lock (its atomic) */
        pkey = hfi1_get_pkey(ibp, qp->s_pkey_index);

        /* Convert dwords to flits */
        len = (*hwords + *nwords) >> 1;

        hfi1_make_16b_hdr(hdr, ppd->lid |
                          (rdma_ah_get_path_bits(&qp->remote_ah_attr) &
                          ((1 << ppd->lmc) - 1)),
                          opa_get_lid(rdma_ah_get_dlid(&qp->remote_ah_attr),
                                      16B), len, pkey, becn, 0, l4, sc5);

        bth0 = pkey | (OP(ACKNOWLEDGE) << 24);
        bth0 |= extra_bytes << 20;
        if (qp->s_mig_state == IB_MIG_MIGRATED)
                bth1 = OPA_BTH_MIG_REQ;
        hfi1_make_bth_aeth(qp, ohdr, bth0, bth1);
}

typedef void (*hfi1_make_rc_ack)(struct hfi1_packet *packet,
                                 struct hfi1_opa_header *opa_hdr,
                                 u8 sc5, bool is_fecn,
                                 u64 *pbc_flags, u32 *hwords,
                                 u32 *nwords);

/* We support only two types - 9B and 16B for now */
static const hfi1_make_rc_ack hfi1_make_rc_ack_tbl[2] = {
        [HFI1_PKT_TYPE_9B] = &hfi1_make_rc_ack_9B,
        [HFI1_PKT_TYPE_16B] = &hfi1_make_rc_ack_16B
};

/**
 * hfi1_send_rc_ack - Construct an ACK packet and send it
 * @qp: a pointer to the QP
 *
 * This is called from hfi1_rc_rcv() and handle_receive_interrupt().
 * Note that RDMA reads and atomics are handled in the
 * send side QP state and send engine.
 */
void hfi1_send_rc_ack(struct hfi1_packet *packet, bool is_fecn)
{
        struct hfi1_ctxtdata *rcd = packet->rcd;
        struct rvt_qp *qp = packet->qp;
        struct hfi1_ibport *ibp = rcd_to_iport(rcd);
        struct hfi1_qp_priv *priv = qp->priv;
        struct hfi1_pportdata *ppd = ppd_from_ibp(ibp);
        u8 sc5 = ibp->sl_to_sc[rdma_ah_get_sl(&qp->remote_ah_attr)];
        u64 pbc, pbc_flags = 0;
        u32 hwords = 0;
        u32 nwords = 0;
        u32 plen;
        struct pio_buf *pbuf;
        struct hfi1_opa_header opa_hdr;

        /* clear the defer count */
        qp->r_adefered = 0;

        /* Don't send ACK or NAK if a RDMA read or atomic is pending. */
        if (qp->s_flags & RVT_S_RESP_PENDING) {
                hfi1_queue_rc_ack(packet, is_fecn);
                return;
        }

        /* Ensure s_rdma_ack_cnt changes are committed */
        if (qp->s_rdma_ack_cnt) {
                hfi1_queue_rc_ack(packet, is_fecn);
                return;
        }

        /* Don't try to send ACKs if the link isn't ACTIVE */
        if (driver_lstate(ppd) != IB_PORT_ACTIVE)
                return;

        /* Make the appropriate header */
        hfi1_make_rc_ack_tbl[priv->hdr_type](packet, &opa_hdr, sc5, is_fecn,
                                             &pbc_flags, &hwords, &nwords);

        plen = 2 /* PBC */ + hwords + nwords;
        pbc = create_pbc(ppd, pbc_flags, qp->srate_mbps,
                         sc_to_vlt(ppd->dd, sc5), plen);
        pbuf = sc_buffer_alloc(rcd->sc, plen, NULL, NULL);
        if (IS_ERR_OR_NULL(pbuf)) {
                /*
                 * We have no room to send at the moment.  Pass
                 * responsibility for sending the ACK to the send engine
                 * so that when enough buffer space becomes available,
                 * the ACK is sent ahead of other outgoing packets.
                 */
                hfi1_queue_rc_ack(packet, is_fecn);
                return;
        }
        trace_ack_output_ibhdr(dd_from_ibdev(qp->ibqp.device),
                               &opa_hdr, ib_is_sc5(sc5));

        /* write the pbc and data */
        ppd->dd->pio_inline_send(ppd->dd, pbuf, pbc,
                                 (priv->hdr_type == HFI1_PKT_TYPE_9B ?
                                 (void *)&opa_hdr.ibh :
                                 (void *)&opa_hdr.opah), hwords);
        return;
}

/**
 * update_num_rd_atomic - update the qp->s_num_rd_atomic
 * @qp: the QP
 * @psn: the packet sequence number to restart at
 * @wqe: the wqe
 *
 * This is called from reset_psn() to update qp->s_num_rd_atomic
 * for the current wqe.
 * Called at interrupt level with the QP s_lock held.
 */
static void update_num_rd_atomic(struct rvt_qp *qp, u32 psn,
                                 struct rvt_swqe *wqe)
{
        u32 opcode = wqe->wr.opcode;

        if (opcode == IB_WR_RDMA_READ ||
            opcode == IB_WR_ATOMIC_CMP_AND_SWP ||
            opcode == IB_WR_ATOMIC_FETCH_AND_ADD) {
                qp->s_num_rd_atomic++;
        } else if (opcode == IB_WR_TID_RDMA_READ) {
                struct tid_rdma_request *req = wqe_to_tid_req(wqe);
                struct hfi1_qp_priv *priv = qp->priv;

                if (cmp_psn(psn, wqe->lpsn) <= 0) {
                        u32 cur_seg;

                        cur_seg = (psn - wqe->psn) / priv->pkts_ps;
                        req->ack_pending = cur_seg - req->comp_seg;
                        priv->pending_tid_r_segs += req->ack_pending;
                        qp->s_num_rd_atomic += req->ack_pending;
                } else {
                        priv->pending_tid_r_segs += req->total_segs;
                        qp->s_num_rd_atomic += req->total_segs;
                }
        }
}

/**
 * reset_psn - reset the QP state to send starting from PSN
 * @qp: the QP
 * @psn: the packet sequence number to restart at
 *
 * This is called from hfi1_rc_rcv() to process an incoming RC ACK
 * for the given QP.
 * Called at interrupt level with the QP s_lock held.
 */
static void reset_psn(struct rvt_qp *qp, u32 psn)
{
        u32 n = qp->s_acked;
        struct rvt_swqe *wqe = rvt_get_swqe_ptr(qp, n);
        u32 opcode;
        struct hfi1_qp_priv *priv = qp->priv;

        lockdep_assert_held(&qp->s_lock);
        qp->s_cur = n;
        priv->pending_tid_r_segs = 0;
        priv->pending_tid_w_resp = 0;
        qp->s_num_rd_atomic = 0;

        /*
         * If we are starting the request from the beginning,
         * let the normal send code handle initialization.
         */
        if (cmp_psn(psn, wqe->psn) <= 0) {
                qp->s_state = OP(SEND_LAST);
                goto done;
        }
        update_num_rd_atomic(qp, psn, wqe);

        /* Find the work request opcode corresponding to the given PSN. */
        for (;;) {
                int diff;

                if (++n == qp->s_size)
                        n = 0;
                if (n == qp->s_tail)
                        break;
                wqe = rvt_get_swqe_ptr(qp, n);
                diff = cmp_psn(psn, wqe->psn);
                if (diff < 0) {
                        /* Point wqe back to the previous one*/
                        wqe = rvt_get_swqe_ptr(qp, qp->s_cur);
                        break;
                }
                qp->s_cur = n;
                /*
                 * If we are starting the request from the beginning,
                 * let the normal send code handle initialization.
                 */
                if (diff == 0) {
                        qp->s_state = OP(SEND_LAST);
                        goto done;
                }

                update_num_rd_atomic(qp, psn, wqe);
        }
        opcode = wqe->wr.opcode;

        /*
         * Set the state to restart in the middle of a request.
         * Don't change the s_sge, s_cur_sge, or s_cur_size.
         * See hfi1_make_rc_req().
         */
        switch (opcode) {
        case IB_WR_SEND:
        case IB_WR_SEND_WITH_IMM:
                qp->s_state = OP(RDMA_READ_RESPONSE_FIRST);
                break;

        case IB_WR_RDMA_WRITE:
        case IB_WR_RDMA_WRITE_WITH_IMM:
                qp->s_state = OP(RDMA_READ_RESPONSE_LAST);
                break;

        case IB_WR_TID_RDMA_WRITE:
                qp->s_state = TID_OP(WRITE_RESP);
                break;

        case IB_WR_RDMA_READ:
                qp->s_state = OP(RDMA_READ_RESPONSE_MIDDLE);
                break;

        case IB_WR_TID_RDMA_READ:
                qp->s_state = TID_OP(READ_RESP);
                break;

        default:
                /*
                 * This case shouldn't happen since its only
                 * one PSN per req.
                 */
                qp->s_state = OP(SEND_LAST);
        }
done:
        priv->s_flags &= ~HFI1_S_TID_WAIT_INTERLCK;
        qp->s_psn = psn;
        /*
         * Set RVT_S_WAIT_PSN as rc_complete() may start the timer
         * asynchronously before the send engine can get scheduled.
         * Doing it in hfi1_make_rc_req() is too late.
         */
        if ((cmp_psn(qp->s_psn, qp->s_sending_hpsn) <= 0) &&
            (cmp_psn(qp->s_sending_psn, qp->s_sending_hpsn) <= 0))
                qp->s_flags |= RVT_S_WAIT_PSN;
        qp->s_flags &= ~HFI1_S_AHG_VALID;
        trace_hfi1_sender_reset_psn(qp);
}

/*
 * Back up requester to resend the last un-ACKed request.
 * The QP r_lock and s_lock should be held and interrupts disabled.
 */
void hfi1_restart_rc(struct rvt_qp *qp, u32 psn, int wait)
{
        struct hfi1_qp_priv *priv = qp->priv;
        struct rvt_swqe *wqe = rvt_get_swqe_ptr(qp, qp->s_acked);
        struct hfi1_ibport *ibp;

        lockdep_assert_held(&qp->r_lock);
        lockdep_assert_held(&qp->s_lock);
        trace_hfi1_sender_restart_rc(qp);
        if (qp->s_retry == 0) {
                if (qp->s_mig_state == IB_MIG_ARMED) {
                        hfi1_migrate_qp(qp);
                        qp->s_retry = qp->s_retry_cnt;
                } else if (qp->s_last == qp->s_acked) {
                        /*
                         * We need special handling for the OPFN request WQEs as
                         * they are not allowed to generate real user errors
                         */
                        if (wqe->wr.opcode == IB_WR_OPFN) {
                                struct hfi1_ibport *ibp =
                                        to_iport(qp->ibqp.device, qp->port_num);
                                /*
                                 * Call opfn_conn_reply() with capcode and
                                 * remaining data as 0 to close out the
                                 * current request
                                 */
                                opfn_conn_reply(qp, priv->opfn.curr);
                                wqe = do_rc_completion(qp, wqe, ibp);
                                qp->s_flags &= ~RVT_S_WAIT_ACK;
                        } else {
                                trace_hfi1_tid_write_sender_restart_rc(qp, 0);
                                if (wqe->wr.opcode == IB_WR_TID_RDMA_READ) {
                                        struct tid_rdma_request *req;

                                        req = wqe_to_tid_req(wqe);
                                        hfi1_kern_exp_rcv_clear_all(req);
                                        hfi1_kern_clear_hw_flow(priv->rcd, qp);
                                }

                                hfi1_trdma_send_complete(qp, wqe,
                                                         IB_WC_RETRY_EXC_ERR);
                                rvt_error_qp(qp, IB_WC_WR_FLUSH_ERR);
                        }
                        return;
                } else { /* need to handle delayed completion */
                        return;
                }
        } else {
                qp->s_retry--;
        }

        ibp = to_iport(qp->ibqp.device, qp->port_num);
        if (wqe->wr.opcode == IB_WR_RDMA_READ ||
            wqe->wr.opcode == IB_WR_TID_RDMA_READ)
                ibp->rvp.n_rc_resends++;
        else
                ibp->rvp.n_rc_resends += delta_psn(qp->s_psn, psn);

        qp->s_flags &= ~(RVT_S_WAIT_FENCE | RVT_S_WAIT_RDMAR |
                         RVT_S_WAIT_SSN_CREDIT | RVT_S_WAIT_PSN |
                         RVT_S_WAIT_ACK | HFI1_S_WAIT_TID_RESP);
        if (wait)
                qp->s_flags |= RVT_S_SEND_ONE;
        reset_psn(qp, psn);
}

/*
 * Set qp->s_sending_psn to the next PSN after the given one.
 * This would be psn+1 except when RDMA reads or TID RDMA ops
 * are present.
 */
static void reset_sending_psn(struct rvt_qp *qp, u32 psn)
{
        struct rvt_swqe *wqe;
        u32 n = qp->s_last;

        lockdep_assert_held(&qp->s_lock);
        /* Find the work request corresponding to the given PSN. */
        for (;;) {
                wqe = rvt_get_swqe_ptr(qp, n);
                if (cmp_psn(psn, wqe->lpsn) <= 0) {
                        if (wqe->wr.opcode == IB_WR_RDMA_READ ||
                            wqe->wr.opcode == IB_WR_TID_RDMA_READ ||
                            wqe->wr.opcode == IB_WR_TID_RDMA_WRITE)
                                qp->s_sending_psn = wqe->lpsn + 1;
                        else
                                qp->s_sending_psn = psn + 1;
                        break;
                }
                if (++n == qp->s_size)
                        n = 0;
                if (n == qp->s_tail)
                        break;
        }
}

/**
 * hfi1_rc_verbs_aborted - handle abort status
 * @qp: the QP
 * @opah: the opa header
 *
 * This code modifies both ACK bit in BTH[2]
 * and the s_flags to go into send one mode.
 *
 * This serves to throttle the send engine to only
 * send a single packet in the likely case the
 * a link has gone down.
 */
void hfi1_rc_verbs_aborted(struct rvt_qp *qp, struct hfi1_opa_header *opah)
{
        struct ib_other_headers *ohdr = hfi1_get_rc_ohdr(opah);
        u8 opcode = ib_bth_get_opcode(ohdr);
        u32 psn;

        /* ignore responses */
        if ((opcode >= OP(RDMA_READ_RESPONSE_FIRST) &&
             opcode <= OP(ATOMIC_ACKNOWLEDGE)) ||
            opcode == TID_OP(READ_RESP) ||
            opcode == TID_OP(WRITE_RESP))
                return;

        psn = ib_bth_get_psn(ohdr) | IB_BTH_REQ_ACK;
        ohdr->bth[2] = cpu_to_be32(psn);
        qp->s_flags |= RVT_S_SEND_ONE;
}

/*
 * This should be called with the QP s_lock held and interrupts disabled.
 */
void hfi1_rc_send_complete(struct rvt_qp *qp, struct hfi1_opa_header *opah)
{
        struct ib_other_headers *ohdr;
        struct hfi1_qp_priv *priv = qp->priv;
        struct rvt_swqe *wqe;
        u32 opcode, head, tail;
        u32 psn;
        struct tid_rdma_request *req;

        lockdep_assert_held(&qp->s_lock);
        if (!(ib_rvt_state_ops[qp->state] & RVT_SEND_OR_FLUSH_OR_RECV_OK))
                return;

        ohdr = hfi1_get_rc_ohdr(opah);
        opcode = ib_bth_get_opcode(ohdr);
        if ((opcode >= OP(RDMA_READ_RESPONSE_FIRST) &&
             opcode <= OP(ATOMIC_ACKNOWLEDGE)) ||
            opcode == TID_OP(READ_RESP) ||
            opcode == TID_OP(WRITE_RESP)) {
                WARN_ON(!qp->s_rdma_ack_cnt);
                qp->s_rdma_ack_cnt--;
                return;
        }

        psn = ib_bth_get_psn(ohdr);
        /*
         * Don't attempt to reset the sending PSN for packets in the
         * KDETH PSN space since the PSN does not match anything.
         */
        if (opcode != TID_OP(WRITE_DATA) &&
            opcode != TID_OP(WRITE_DATA_LAST) &&
            opcode != TID_OP(ACK) && opcode != TID_OP(RESYNC))
                reset_sending_psn(qp, psn);

        /* Handle TID RDMA WRITE packets differently */
        if (opcode >= TID_OP(WRITE_REQ) &&
            opcode <= TID_OP(WRITE_DATA_LAST)) {
                head = priv->s_tid_head;
                tail = priv->s_tid_cur;
                /*
                 * s_tid_cur is set to s_tid_head in the case, where
                 * a new TID RDMA request is being started and all
                 * previous ones have been completed.
                 * Therefore, we need to do a secondary check in order
                 * to properly determine whether we should start the
                 * RC timer.
                 */
                wqe = rvt_get_swqe_ptr(qp, tail);
                req = wqe_to_tid_req(wqe);
                if (head == tail && req->comp_seg < req->total_segs) {
                        if (tail == 0)
                                tail = qp->s_size - 1;
                        else
                                tail -= 1;
                }
        } else {
                head = qp->s_tail;
                tail = qp->s_acked;
        }

        /*
         * Start timer after a packet requesting an ACK has been sent and
         * there are still requests that haven't been acked.
         */
        if ((psn & IB_BTH_REQ_ACK) && tail != head &&
            opcode != TID_OP(WRITE_DATA) && opcode != TID_OP(WRITE_DATA_LAST) &&
            opcode != TID_OP(RESYNC) &&
            !(qp->s_flags &
              (RVT_S_TIMER | RVT_S_WAIT_RNR | RVT_S_WAIT_PSN)) &&
            (ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK)) {
                if (opcode == TID_OP(READ_REQ))
                        rvt_add_retry_timer_ext(qp, priv->timeout_shift);
                else
                        rvt_add_retry_timer(qp);
        }

        /* Start TID RDMA ACK timer */
        if ((opcode == TID_OP(WRITE_DATA) ||
             opcode == TID_OP(WRITE_DATA_LAST) ||
             opcode == TID_OP(RESYNC)) &&
            (psn & IB_BTH_REQ_ACK) &&
            !(priv->s_flags & HFI1_S_TID_RETRY_TIMER) &&
            (ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK)) {
                /*
                 * The TID RDMA ACK packet could be received before this
                 * function is called. Therefore, add the timer only if TID
                 * RDMA ACK packets are actually pending.
                 */
                wqe = rvt_get_swqe_ptr(qp, qp->s_acked);
                req = wqe_to_tid_req(wqe);
                if (wqe->wr.opcode == IB_WR_TID_RDMA_WRITE &&
                    req->ack_seg < req->cur_seg)
                        hfi1_add_tid_retry_timer(qp);
        }

        while (qp->s_last != qp->s_acked) {
                wqe = rvt_get_swqe_ptr(qp, qp->s_last);
                if (cmp_psn(wqe->lpsn, qp->s_sending_psn) >= 0 &&
                    cmp_psn(qp->s_sending_psn, qp->s_sending_hpsn) <= 0)
                        break;
                trdma_clean_swqe(qp, wqe);
                trace_hfi1_qp_send_completion(qp, wqe, qp->s_last);
                rvt_qp_complete_swqe(qp,
                                     wqe,
                                     ib_hfi1_wc_opcode[wqe->wr.opcode],
                                     IB_WC_SUCCESS);
        }
        /*
         * If we were waiting for sends to complete before re-sending,
         * and they are now complete, restart sending.
         */
        trace_hfi1_sendcomplete(qp, psn);
        if (qp->s_flags & RVT_S_WAIT_PSN &&
            cmp_psn(qp->s_sending_psn, qp->s_sending_hpsn) > 0) {
                qp->s_flags &= ~RVT_S_WAIT_PSN;
                qp->s_sending_psn = qp->s_psn;
                qp->s_sending_hpsn = qp->s_psn - 1;
                hfi1_schedule_send(qp);
        }
}

static inline void update_last_psn(struct rvt_qp *qp, u32 psn)
{
        qp->s_last_psn = psn;
}

/*
 * Generate a SWQE completion.
 * This is similar to hfi1_send_complete but has to check to be sure
 * that the SGEs are not being referenced if the SWQE is being resent.
 */
struct rvt_swqe *do_rc_completion(struct rvt_qp *qp,
                                  struct rvt_swqe *wqe,
                                  struct hfi1_ibport *ibp)
{
        struct hfi1_qp_priv *priv = qp->priv;

        lockdep_assert_held(&qp->s_lock);
        /*
         * Don't decrement refcount and don't generate a
         * completion if the SWQE is being resent until the send
         * is finished.
         */
        trace_hfi1_rc_completion(qp, wqe->lpsn);
        if (cmp_psn(wqe->lpsn, qp->s_sending_psn) < 0 ||
            cmp_psn(qp->s_sending_psn, qp->s_sending_hpsn) > 0) {
                trdma_clean_swqe(qp, wqe);
                trace_hfi1_qp_send_completion(qp, wqe, qp->s_last);
                rvt_qp_complete_swqe(qp,
                                     wqe,
                                     ib_hfi1_wc_opcode[wqe->wr.opcode],
                                     IB_WC_SUCCESS);
        } else {
                struct hfi1_pportdata *ppd = ppd_from_ibp(ibp);

                this_cpu_inc(*ibp->rvp.rc_delayed_comp);
                /*
                 * If send progress not running attempt to progress
                 * SDMA queue.
                 */
                if (ppd->dd->flags & HFI1_HAS_SEND_DMA) {
                        struct sdma_engine *engine;
                        u8 sl = rdma_ah_get_sl(&qp->remote_ah_attr);
                        u8 sc5;

                        /* For now use sc to find engine */
                        sc5 = ibp->sl_to_sc[sl];
                        engine = qp_to_sdma_engine(qp, sc5);
                        sdma_engine_progress_schedule(engine);
                }
        }

        qp->s_retry = qp->s_retry_cnt;
        /*
         * Don't update the last PSN if the request being completed is
         * a TID RDMA WRITE request.
         * Completion of the TID RDMA WRITE requests are done by the
         * TID RDMA ACKs and as such could be for a request that has
         * already been ACKed as far as the IB state machine is
         * concerned.
         */
        if (wqe->wr.opcode != IB_WR_TID_RDMA_WRITE)
                update_last_psn(qp, wqe->lpsn);

        /*
         * If we are completing a request which is in the process of
         * being resent, we can stop re-sending it since we know the
         * responder has already seen it.
         */
        if (qp->s_acked == qp->s_cur) {
                if (++qp->s_cur >= qp->s_size)
                        qp->s_cur = 0;
                qp->s_acked = qp->s_cur;
                wqe = rvt_get_swqe_ptr(qp, qp->s_cur);
                if (qp->s_acked != qp->s_tail) {
                        qp->s_state = OP(SEND_LAST);
                        qp->s_psn = wqe->psn;
                }
        } else {
                if (++qp->s_acked >= qp->s_size)
                        qp->s_acked = 0;
                if (qp->state == IB_QPS_SQD && qp->s_acked == qp->s_cur)
                        qp->s_draining = 0;
                wqe = rvt_get_swqe_ptr(qp, qp->s_acked);
        }
        if (priv->s_flags & HFI1_S_TID_WAIT_INTERLCK) {
                priv->s_flags &= ~HFI1_S_TID_WAIT_INTERLCK;
                hfi1_schedule_send(qp);
        }
        return wqe;
}

static void set_restart_qp(struct rvt_qp *qp, struct hfi1_ctxtdata *rcd)
{
        /* Retry this request. */
        if (!(qp->r_flags & RVT_R_RDMAR_SEQ)) {
                qp->r_flags |= RVT_R_RDMAR_SEQ;
                hfi1_restart_rc(qp, qp->s_last_psn + 1, 0);
                if (list_empty(&qp->rspwait)) {
                        qp->r_flags |= RVT_R_RSP_SEND;
                        rvt_get_qp(qp);
                        list_add_tail(&qp->rspwait, &rcd->qp_wait_list);
                }
        }
}

/**
 * update_qp_retry_state - Update qp retry state.
 * @qp: the QP
 * @psn: the packet sequence number of the TID RDMA WRITE RESP.
 * @spsn:  The start psn for the given TID RDMA WRITE swqe.
 * @lpsn:  The last psn for the given TID RDMA WRITE swqe.
 *
 * This function is called to update the qp retry state upon
 * receiving a TID WRITE RESP after the qp is scheduled to retry
 * a request.
 */
static void update_qp_retry_state(struct rvt_qp *qp, u32 psn, u32 spsn,
                                  u32 lpsn)
{
        struct hfi1_qp_priv *qpriv = qp->priv;

        qp->s_psn = psn + 1;
        /*
         * If this is the first TID RDMA WRITE RESP packet for the current
         * request, change the s_state so that the retry will be processed
         * correctly. Similarly, if this is the last TID RDMA WRITE RESP
         * packet, change the s_state and advance the s_cur.
         */
        if (cmp_psn(psn, lpsn) >= 0) {
                qp->s_cur = qpriv->s_tid_cur + 1;
                if (qp->s_cur >= qp->s_size)
                        qp->s_cur = 0;
                qp->s_state = TID_OP(WRITE_REQ);
        } else  if (!cmp_psn(psn, spsn)) {
                qp->s_cur = qpriv->s_tid_cur;
                qp->s_state = TID_OP(WRITE_RESP);
        }
}

/**
 * do_rc_ack - process an incoming RC ACK
 * @qp: the QP the ACK came in on
 * @psn: the packet sequence number of the ACK

 * @opcode: the opcode of the request that resulted in the ACK
 *
 * This is called from rc_rcv_resp() to process an incoming RC ACK
 * for the given QP.
 * May be called at interrupt level, with the QP s_lock held.
 * Returns 1 if OK, 0 if current operation should be aborted (NAK).
 */
int do_rc_ack(struct rvt_qp *qp, u32 aeth, u32 psn, int opcode,
              u64 val, struct hfi1_ctxtdata *rcd)
{
        struct hfi1_ibport *ibp;
        enum ib_wc_status status;
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct rvt_swqe *wqe;
        int ret = 0;
        u32 ack_psn;
        int diff;
        struct rvt_dev_info *rdi;

        lockdep_assert_held(&qp->s_lock);
        /*
         * Note that NAKs implicitly ACK outstanding SEND and RDMA write
         * requests and implicitly NAK RDMA read and atomic requests issued
         * before the NAK'ed request.  The MSN won't include the NAK'ed
         * request but will include an ACK'ed request(s).
         */
        ack_psn = psn;
        if (aeth >> IB_AETH_NAK_SHIFT)
                ack_psn--;
        wqe = rvt_get_swqe_ptr(qp, qp->s_acked);
        ibp = rcd_to_iport(rcd);

        /*
         * The MSN might be for a later WQE than the PSN indicates so
         * only complete WQEs that the PSN finishes.
         */
        while ((diff = delta_psn(ack_psn, wqe->lpsn)) >= 0) {
                /*
                 * RDMA_READ_RESPONSE_ONLY is a special case since
                 * we want to generate completion events for everything
                 * before the RDMA read, copy the data, then generate
                 * the completion for the read.
                 */
                if (wqe->wr.opcode == IB_WR_RDMA_READ &&
                    opcode == OP(RDMA_READ_RESPONSE_ONLY) &&
                    diff == 0) {
                        ret = 1;
                        goto bail_stop;
                }
                /*
                 * If this request is a RDMA read or atomic, and the ACK is
                 * for a later operation, this ACK NAKs the RDMA read or
                 * atomic.  In other words, only a RDMA_READ_LAST or ONLY
                 * can ACK a RDMA read and likewise for atomic ops.  Note
                 * that the NAK case can only happen if relaxed ordering is
                 * used and requests are sent after an RDMA read or atomic
                 * is sent but before the response is received.
                 */
                if ((wqe->wr.opcode == IB_WR_RDMA_READ &&
                     (opcode != OP(RDMA_READ_RESPONSE_LAST) || diff != 0)) ||
                    (wqe->wr.opcode == IB_WR_TID_RDMA_READ &&
                     (opcode != TID_OP(READ_RESP) || diff != 0)) ||
                    ((wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP ||
                      wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD) &&
                     (opcode != OP(ATOMIC_ACKNOWLEDGE) || diff != 0)) ||
                    (wqe->wr.opcode == IB_WR_TID_RDMA_WRITE &&
                     (delta_psn(psn, qp->s_last_psn) != 1))) {
                        set_restart_qp(qp, rcd);
                        /*
                         * No need to process the ACK/NAK since we are
                         * restarting an earlier request.
                         */
                        goto bail_stop;
                }
                if (wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP ||
                    wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD) {
                        u64 *vaddr = wqe->sg_list[0].vaddr;
                        *vaddr = val;
                }
                if (wqe->wr.opcode == IB_WR_OPFN)
                        opfn_conn_reply(qp, val);

                if (qp->s_num_rd_atomic &&
                    (wqe->wr.opcode == IB_WR_RDMA_READ ||
                     wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP ||
                     wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD)) {
                        qp->s_num_rd_atomic--;
                        /* Restart sending task if fence is complete */
                        if ((qp->s_flags & RVT_S_WAIT_FENCE) &&
                            !qp->s_num_rd_atomic) {
                                qp->s_flags &= ~(RVT_S_WAIT_FENCE |
                                                 RVT_S_WAIT_ACK);
                                hfi1_schedule_send(qp);
                        } else if (qp->s_flags & RVT_S_WAIT_RDMAR) {
                                qp->s_flags &= ~(RVT_S_WAIT_RDMAR |
                                                 RVT_S_WAIT_ACK);
                                hfi1_schedule_send(qp);
                        }
                }

                /*
                 * TID RDMA WRITE requests will be completed by the TID RDMA
                 * ACK packet handler (see tid_rdma.c).
                 */
                if (wqe->wr.opcode == IB_WR_TID_RDMA_WRITE)
                        break;

                wqe = do_rc_completion(qp, wqe, ibp);
                if (qp->s_acked == qp->s_tail)
                        break;
        }

        trace_hfi1_rc_ack_do(qp, aeth, psn, wqe);
        trace_hfi1_sender_do_rc_ack(qp);
        switch (aeth >> IB_AETH_NAK_SHIFT) {
        case 0:         /* ACK */
                this_cpu_inc(*ibp->rvp.rc_acks);
                if (wqe->wr.opcode == IB_WR_TID_RDMA_READ) {
                        if (wqe_to_tid_req(wqe)->ack_pending)
                                rvt_mod_retry_timer_ext(qp,
                                                        qpriv->timeout_shift);
                        else
                                rvt_stop_rc_timers(qp);
                } else if (qp->s_acked != qp->s_tail) {
                        struct rvt_swqe *__w = NULL;

                        if (qpriv->s_tid_cur != HFI1_QP_WQE_INVALID)
                                __w = rvt_get_swqe_ptr(qp, qpriv->s_tid_cur);

                        /*
                         * Stop timers if we've received all of the TID RDMA
                         * WRITE * responses.
                         */
                        if (__w && __w->wr.opcode == IB_WR_TID_RDMA_WRITE &&
                            opcode == TID_OP(WRITE_RESP)) {
                                /*
                                 * Normally, the loop above would correctly
                                 * process all WQEs from s_acked onward and
                                 * either complete them or check for correct
                                 * PSN sequencing.
                                 * However, for TID RDMA, due to pipelining,
                                 * the response may not be for the request at
                                 * s_acked so the above look would just be
                                 * skipped. This does not allow for checking
                                 * the PSN sequencing. It has to be done
                                 * separately.
                                 */
                                if (cmp_psn(psn, qp->s_last_psn + 1)) {
                                        set_restart_qp(qp, rcd);
                                        goto bail_stop;
                                }
                                /*
                                 * If the psn is being resent, stop the
                                 * resending.
                                 */
                                if (qp->s_cur != qp->s_tail &&
                                    cmp_psn(qp->s_psn, psn) <= 0)
                                        update_qp_retry_state(qp, psn,
                                                              __w->psn,
                                                              __w->lpsn);
                                else if (--qpriv->pending_tid_w_resp)
                                        rvt_mod_retry_timer(qp);
                                else
                                        rvt_stop_rc_timers(qp);
                        } else {
                                /*
                                 * We are expecting more ACKs so
                                 * mod the retry timer.
                                 */
                                rvt_mod_retry_timer(qp);
                                /*
                                 * We can stop re-sending the earlier packets
                                 * and continue with the next packet the
                                 * receiver wants.
                                 */
                                if (cmp_psn(qp->s_psn, psn) <= 0)
                                        reset_psn(qp, psn + 1);
                        }
                } else {
                        /* No more acks - kill all timers */
                        rvt_stop_rc_timers(qp);
                        if (cmp_psn(qp->s_psn, psn) <= 0) {
                                qp->s_state = OP(SEND_LAST);
                                qp->s_psn = psn + 1;
                        }
                }
                if (qp->s_flags & RVT_S_WAIT_ACK) {
                        qp->s_flags &= ~RVT_S_WAIT_ACK;
                        hfi1_schedule_send(qp);
                }
                rvt_get_credit(qp, aeth);
                qp->s_rnr_retry = qp->s_rnr_retry_cnt;
                qp->s_retry = qp->s_retry_cnt;
                /*
                 * If the current request is a TID RDMA WRITE request and the
                 * response is not a TID RDMA WRITE RESP packet, s_last_psn
                 * can't be advanced.
                 */
                if (wqe->wr.opcode == IB_WR_TID_RDMA_WRITE &&
                    opcode != TID_OP(WRITE_RESP) &&
                    cmp_psn(psn, wqe->psn) >= 0)
                        return 1;
                update_last_psn(qp, psn);
                return 1;

        case 1:         /* RNR NAK */
                ibp->rvp.n_rnr_naks++;
                if (qp->s_acked == qp->s_tail)
                        goto bail_stop;
                if (qp->s_flags & RVT_S_WAIT_RNR)
                        goto bail_stop;
                rdi = ib_to_rvt(qp->ibqp.device);
                if (qp->s_rnr_retry == 0 &&
                    !((rdi->post_parms[wqe->wr.opcode].flags &
                      RVT_OPERATION_IGN_RNR_CNT) &&
                      qp->s_rnr_retry_cnt == 0)) {
                        status = IB_WC_RNR_RETRY_EXC_ERR;
                        goto class_b;
                }
                if (qp->s_rnr_retry_cnt < 7 && qp->s_rnr_retry_cnt > 0)
                        qp->s_rnr_retry--;

                /*
                 * The last valid PSN is the previous PSN. For TID RDMA WRITE
                 * request, s_last_psn should be incremented only when a TID
                 * RDMA WRITE RESP is received to avoid skipping lost TID RDMA
                 * WRITE RESP packets.
                 */
                if (wqe->wr.opcode == IB_WR_TID_RDMA_WRITE) {
                        reset_psn(qp, qp->s_last_psn + 1);
                } else {
                        update_last_psn(qp, psn - 1);
                        reset_psn(qp, psn);
                }

                ibp->rvp.n_rc_resends += delta_psn(qp->s_psn, psn);
                qp->s_flags &= ~(RVT_S_WAIT_SSN_CREDIT | RVT_S_WAIT_ACK);
                rvt_stop_rc_timers(qp);
                rvt_add_rnr_timer(qp, aeth);
                return 0;

        case 3:         /* NAK */
                if (qp->s_acked == qp->s_tail)
                        goto bail_stop;
                /* The last valid PSN is the previous PSN. */
                update_last_psn(qp, psn - 1);
                switch ((aeth >> IB_AETH_CREDIT_SHIFT) &
                        IB_AETH_CREDIT_MASK) {
                case 0: /* PSN sequence error */
                        ibp->rvp.n_seq_naks++;
                        /*
                         * Back up to the responder's expected PSN.
                         * Note that we might get a NAK in the middle of an
                         * RDMA READ response which terminates the RDMA
                         * READ.
                         */
                        hfi1_restart_rc(qp, psn, 0);
                        hfi1_schedule_send(qp);
                        break;

                case 1: /* Invalid Request */
                        status = IB_WC_REM_INV_REQ_ERR;
                        ibp->rvp.n_other_naks++;
                        goto class_b;

                case 2: /* Remote Access Error */
                        status = IB_WC_REM_ACCESS_ERR;
                        ibp->rvp.n_other_naks++;
                        goto class_b;

                case 3: /* Remote Operation Error */
                        status = IB_WC_REM_OP_ERR;
                        ibp->rvp.n_other_naks++;
class_b:
                        if (qp->s_last == qp->s_acked) {
                                if (wqe->wr.opcode == IB_WR_TID_RDMA_READ)
                                        hfi1_kern_read_tid_flow_free(qp);

                                hfi1_trdma_send_complete(qp, wqe, status);
                                rvt_error_qp(qp, IB_WC_WR_FLUSH_ERR);
                        }
                        break;

                default:
                        /* Ignore other reserved NAK error codes */
                        goto reserved;
                }
                qp->s_retry = qp->s_retry_cnt;
                qp->s_rnr_retry = qp->s_rnr_retry_cnt;
                goto bail_stop;

        default:                /* 2: reserved */
reserved:
                /* Ignore reserved NAK codes. */
                goto bail_stop;
        }
        /* cannot be reached  */
bail_stop:
        rvt_stop_rc_timers(qp);
        return ret;
}

/*
 * We have seen an out of sequence RDMA read middle or last packet.
 * This ACKs SENDs and RDMA writes up to the first RDMA read or atomic SWQE.
 */
static void rdma_seq_err(struct rvt_qp *qp, struct hfi1_ibport *ibp, u32 psn,
                         struct hfi1_ctxtdata *rcd)
{
        struct rvt_swqe *wqe;

        lockdep_assert_held(&qp->s_lock);
        /* Remove QP from retry timer */
        rvt_stop_rc_timers(qp);

        wqe = rvt_get_swqe_ptr(qp, qp->s_acked);

        while (cmp_psn(psn, wqe->lpsn) > 0) {
                if (wqe->wr.opcode == IB_WR_RDMA_READ ||
                    wqe->wr.opcode == IB_WR_TID_RDMA_READ ||
                    wqe->wr.opcode == IB_WR_TID_RDMA_WRITE ||
                    wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP ||
                    wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD)
                        break;
                wqe = do_rc_completion(qp, wqe, ibp);
        }

        ibp->rvp.n_rdma_seq++;
        qp->r_flags |= RVT_R_RDMAR_SEQ;
        hfi1_restart_rc(qp, qp->s_last_psn + 1, 0);
        if (list_empty(&qp->rspwait)) {
                qp->r_flags |= RVT_R_RSP_SEND;
                rvt_get_qp(qp);
                list_add_tail(&qp->rspwait, &rcd->qp_wait_list);
        }
}

/**
 * rc_rcv_resp - process an incoming RC response packet
 * @packet: data packet information
 *
 * This is called from hfi1_rc_rcv() to process an incoming RC response
 * packet for the given QP.
 * Called at interrupt level.
 */
static void rc_rcv_resp(struct hfi1_packet *packet)
{
        struct hfi1_ctxtdata *rcd = packet->rcd;
        void *data = packet->payload;
        u32 tlen = packet->tlen;
        struct rvt_qp *qp = packet->qp;
        struct hfi1_ibport *ibp;
        struct ib_other_headers *ohdr = packet->ohdr;
        struct rvt_swqe *wqe;
        enum ib_wc_status status;
        unsigned long flags;
        int diff;
        u64 val;
        u32 aeth;
        u32 psn = ib_bth_get_psn(packet->ohdr);
        u32 pmtu = qp->pmtu;
        u16 hdrsize = packet->hlen;
        u8 opcode = packet->opcode;
        u8 pad = packet->pad;
        u8 extra_bytes = pad + packet->extra_byte + (SIZE_OF_CRC << 2);

        spin_lock_irqsave(&qp->s_lock, flags);
        trace_hfi1_ack(qp, psn);

        /* Ignore invalid responses. */
        if (cmp_psn(psn, READ_ONCE(qp->s_next_psn)) >= 0)
                goto ack_done;

        /* Ignore duplicate responses. */
        diff = cmp_psn(psn, qp->s_last_psn);
        if (unlikely(diff <= 0)) {
                /* Update credits for "ghost" ACKs */
                if (diff == 0 && opcode == OP(ACKNOWLEDGE)) {
                        aeth = be32_to_cpu(ohdr->u.aeth);
                        if ((aeth >> IB_AETH_NAK_SHIFT) == 0)
                                rvt_get_credit(qp, aeth);
                }
                goto ack_done;
        }

        /*
         * Skip everything other than the PSN we expect, if we are waiting
         * for a reply to a restarted RDMA read or atomic op.
         */
        if (qp->r_flags & RVT_R_RDMAR_SEQ) {
                if (cmp_psn(psn, qp->s_last_psn + 1) != 0)
                        goto ack_done;
                qp->r_flags &= ~RVT_R_RDMAR_SEQ;
        }

        if (unlikely(qp->s_acked == qp->s_tail))
                goto ack_done;
        wqe = rvt_get_swqe_ptr(qp, qp->s_acked);
        status = IB_WC_SUCCESS;

        switch (opcode) {
        case OP(ACKNOWLEDGE):
        case OP(ATOMIC_ACKNOWLEDGE):
        case OP(RDMA_READ_RESPONSE_FIRST):
                aeth = be32_to_cpu(ohdr->u.aeth);
                if (opcode == OP(ATOMIC_ACKNOWLEDGE))
                        val = ib_u64_get(&ohdr->u.at.atomic_ack_eth);
                else
                        val = 0;
                if (!do_rc_ack(qp, aeth, psn, opcode, val, rcd) ||
                    opcode != OP(RDMA_READ_RESPONSE_FIRST))
                        goto ack_done;
                wqe = rvt_get_swqe_ptr(qp, qp->s_acked);
                if (unlikely(wqe->wr.opcode != IB_WR_RDMA_READ))
                        goto ack_op_err;
                /*
                 * If this is a response to a resent RDMA read, we
                 * have to be careful to copy the data to the right
                 * location.
                 */
                qp->s_rdma_read_len = restart_sge(&qp->s_rdma_read_sge,
                                                  wqe, psn, pmtu);
                goto read_middle;

        case OP(RDMA_READ_RESPONSE_MIDDLE):
                /* no AETH, no ACK */
                if (unlikely(cmp_psn(psn, qp->s_last_psn + 1)))
                        goto ack_seq_err;
                if (unlikely(wqe->wr.opcode != IB_WR_RDMA_READ))
                        goto ack_op_err;
read_middle:
                if (unlikely(tlen != (hdrsize + pmtu + extra_bytes)))
                        goto ack_len_err;
                if (unlikely(pmtu >= qp->s_rdma_read_len))
                        goto ack_len_err;

                /*
                 * We got a response so update the timeout.
                 * 4.096 usec. * (1 << qp->timeout)
                 */
                rvt_mod_retry_timer(qp);
                if (qp->s_flags & RVT_S_WAIT_ACK) {
                        qp->s_flags &= ~RVT_S_WAIT_ACK;
                        hfi1_schedule_send(qp);
                }

                if (opcode == OP(RDMA_READ_RESPONSE_MIDDLE))
                        qp->s_retry = qp->s_retry_cnt;

                /*
                 * Update the RDMA receive state but do the copy w/o
                 * holding the locks and blocking interrupts.
                 */
                qp->s_rdma_read_len -= pmtu;
                update_last_psn(qp, psn);
                spin_unlock_irqrestore(&qp->s_lock, flags);
                rvt_copy_sge(qp, &qp->s_rdma_read_sge,
                             data, pmtu, false, false);
                goto bail;

        case OP(RDMA_READ_RESPONSE_ONLY):
                aeth = be32_to_cpu(ohdr->u.aeth);
                if (!do_rc_ack(qp, aeth, psn, opcode, 0, rcd))
                        goto ack_done;
                /*
                 * Check that the data size is >= 0 && <= pmtu.
                 * Remember to account for ICRC (4).
                 */
                if (unlikely(tlen < (hdrsize + extra_bytes)))
                        goto ack_len_err;
                /*
                 * If this is a response to a resent RDMA read, we
                 * have to be careful to copy the data to the right
                 * location.
                 */
                wqe = rvt_get_swqe_ptr(qp, qp->s_acked);
                qp->s_rdma_read_len = restart_sge(&qp->s_rdma_read_sge,
                                                  wqe, psn, pmtu);
                goto read_last;

        case OP(RDMA_READ_RESPONSE_LAST):
                /* ACKs READ req. */
                if (unlikely(cmp_psn(psn, qp->s_last_psn + 1)))
                        goto ack_seq_err;
                if (unlikely(wqe->wr.opcode != IB_WR_RDMA_READ))
                        goto ack_op_err;
                /*
                 * Check that the data size is >= 1 && <= pmtu.
                 * Remember to account for ICRC (4).
                 */
                if (unlikely(tlen <= (hdrsize + extra_bytes)))
                        goto ack_len_err;
read_last:
                tlen -= hdrsize + extra_bytes;
                if (unlikely(tlen != qp->s_rdma_read_len))
                        goto ack_len_err;
                aeth = be32_to_cpu(ohdr->u.aeth);
                rvt_copy_sge(qp, &qp->s_rdma_read_sge,
                             data, tlen, false, false);
                WARN_ON(qp->s_rdma_read_sge.num_sge);
                (void)do_rc_ack(qp, aeth, psn,
                                 OP(RDMA_READ_RESPONSE_LAST), 0, rcd);
                goto ack_done;
        }

ack_op_err:
        status = IB_WC_LOC_QP_OP_ERR;
        goto ack_err;

ack_seq_err:
        ibp = rcd_to_iport(rcd);
        rdma_seq_err(qp, ibp, psn, rcd);
        goto ack_done;

ack_len_err:
        status = IB_WC_LOC_LEN_ERR;
ack_err:
        if (qp->s_last == qp->s_acked) {
                rvt_send_complete(qp, wqe, status);
                rvt_error_qp(qp, IB_WC_WR_FLUSH_ERR);
        }
ack_done:
        spin_unlock_irqrestore(&qp->s_lock, flags);
bail:
        return;
}

static inline void rc_cancel_ack(struct rvt_qp *qp)
{
        qp->r_adefered = 0;
        if (list_empty(&qp->rspwait))
                return;
        list_del_init(&qp->rspwait);
        qp->r_flags &= ~RVT_R_RSP_NAK;
        rvt_put_qp(qp);
}

/**
 * rc_rcv_error - process an incoming duplicate or error RC packet
 * @ohdr: the other headers for this packet
 * @data: the packet data
 * @qp: the QP for this packet
 * @opcode: the opcode for this packet
 * @psn: the packet sequence number for this packet
 * @diff: the difference between the PSN and the expected PSN
 *
 * This is called from hfi1_rc_rcv() to process an unexpected
 * incoming RC packet for the given QP.
 * Called at interrupt level.
 * Return 1 if no more processing is needed; otherwise return 0 to
 * schedule a response to be sent.
 */
static noinline int rc_rcv_error(struct ib_other_headers *ohdr, void *data,
                                 struct rvt_qp *qp, u32 opcode, u32 psn,
                                 int diff, struct hfi1_ctxtdata *rcd)
{
        struct hfi1_ibport *ibp = rcd_to_iport(rcd);
        struct rvt_ack_entry *e;
        unsigned long flags;
        u8 prev;
        u8 mra; /* most recent ACK */
        bool old_req;

        trace_hfi1_rcv_error(qp, psn);
        if (diff > 0) {
                /*
                 * Packet sequence error.
                 * A NAK will ACK earlier sends and RDMA writes.
                 * Don't queue the NAK if we already sent one.
                 */
                if (!qp->r_nak_state) {
                        ibp->rvp.n_rc_seqnak++;
                        qp->r_nak_state = IB_NAK_PSN_ERROR;
                        /* Use the expected PSN. */
                        qp->r_ack_psn = qp->r_psn;
                        /*
                         * Wait to send the sequence NAK until all packets
                         * in the receive queue have been processed.
                         * Otherwise, we end up propagating congestion.
                         */
                        rc_defered_ack(rcd, qp);
                }
                goto done;
        }

        /*
         * Handle a duplicate request.  Don't re-execute SEND, RDMA
         * write or atomic op.  Don't NAK errors, just silently drop
         * the duplicate request.  Note that r_sge, r_len, and
         * r_rcv_len may be in use so don't modify them.
         *
         * We are supposed to ACK the earliest duplicate PSN but we
         * can coalesce an outstanding duplicate ACK.  We have to
         * send the earliest so that RDMA reads can be restarted at
         * the requester's expected PSN.
         *
         * First, find where this duplicate PSN falls within the
         * ACKs previously sent.
         * old_req is true if there is an older response that is scheduled
         * to be sent before sending this one.
         */
        e = NULL;
        old_req = 1;
        ibp->rvp.n_rc_dupreq++;

        spin_lock_irqsave(&qp->s_lock, flags);

        e = find_prev_entry(qp, psn, &prev, &mra, &old_req);

        switch (opcode) {
        case OP(RDMA_READ_REQUEST): {
                struct ib_reth *reth;
                u32 offset;
                u32 len;

                /*
                 * If we didn't find the RDMA read request in the ack queue,
                 * we can ignore this request.
                 */
                if (!e || e->opcode != OP(RDMA_READ_REQUEST))
                        goto unlock_done;
                /* RETH comes after BTH */
                reth = &ohdr->u.rc.reth;
                /*
                 * Address range must be a subset of the original
                 * request and start on pmtu boundaries.
                 * We reuse the old ack_queue slot since the requester
                 * should not back up and request an earlier PSN for the
                 * same request.
                 */
                offset = delta_psn(psn, e->psn) * qp->pmtu;
                len = be32_to_cpu(reth->length);
                if (unlikely(offset + len != e->rdma_sge.sge_length))
                        goto unlock_done;
                release_rdma_sge_mr(e);
                if (len != 0) {
                        u32 rkey = be32_to_cpu(reth->rkey);
                        u64 vaddr = get_ib_reth_vaddr(reth);
                        int ok;

                        ok = rvt_rkey_ok(qp, &e->rdma_sge, len, vaddr, rkey,
                                         IB_ACCESS_REMOTE_READ);
                        if (unlikely(!ok))
                                goto unlock_done;
                } else {
                        e->rdma_sge.vaddr = NULL;
                        e->rdma_sge.length = 0;
                        e->rdma_sge.sge_length = 0;
                }
                e->psn = psn;
                if (old_req)
                        goto unlock_done;
                if (qp->s_acked_ack_queue == qp->s_tail_ack_queue)
                        qp->s_acked_ack_queue = prev;
                qp->s_tail_ack_queue = prev;
                break;
        }

        case OP(COMPARE_SWAP):
        case OP(FETCH_ADD): {
                /*
                 * If we didn't find the atomic request in the ack queue
                 * or the send engine is already backed up to send an
                 * earlier entry, we can ignore this request.
                 */
                if (!e || e->opcode != (u8)opcode || old_req)
                        goto unlock_done;
                if (qp->s_tail_ack_queue == qp->s_acked_ack_queue)
                        qp->s_acked_ack_queue = prev;
                qp->s_tail_ack_queue = prev;
                break;
        }

        default:
                /*
                 * Ignore this operation if it doesn't request an ACK
                 * or an earlier RDMA read or atomic is going to be resent.
                 */
                if (!(psn & IB_BTH_REQ_ACK) || old_req)
                        goto unlock_done;
                /*
                 * Resend the most recent ACK if this request is
                 * after all the previous RDMA reads and atomics.
                 */
                if (mra == qp->r_head_ack_queue) {
                        spin_unlock_irqrestore(&qp->s_lock, flags);
                        qp->r_nak_state = 0;
                        qp->r_ack_psn = qp->r_psn - 1;
                        goto send_ack;
                }

                /*
                 * Resend the RDMA read or atomic op which
                 * ACKs this duplicate request.
                 */
                if (qp->s_tail_ack_queue == qp->s_acked_ack_queue)
                        qp->s_acked_ack_queue = mra;
                qp->s_tail_ack_queue = mra;
                break;
        }
        qp->s_ack_state = OP(ACKNOWLEDGE);
        qp->s_flags |= RVT_S_RESP_PENDING;
        qp->r_nak_state = 0;
        hfi1_schedule_send(qp);

unlock_done:
        spin_unlock_irqrestore(&qp->s_lock, flags);
done:
        return 1;

send_ack:
        return 0;
}

static void log_cca_event(struct hfi1_pportdata *ppd, u8 sl, u32 rlid,
                          u32 lqpn, u32 rqpn, u8 svc_type)
{
        struct opa_hfi1_cong_log_event_internal *cc_event;
        unsigned long flags;

        if (sl >= OPA_MAX_SLS)
                return;

        spin_lock_irqsave(&ppd->cc_log_lock, flags);

        ppd->threshold_cong_event_map[sl / 8] |= 1 << (sl % 8);
        ppd->threshold_event_counter++;

        cc_event = &ppd->cc_events[ppd->cc_log_idx++];
        if (ppd->cc_log_idx == OPA_CONG_LOG_ELEMS)
                ppd->cc_log_idx = 0;
        cc_event->lqpn = lqpn & RVT_QPN_MASK;
        cc_event->rqpn = rqpn & RVT_QPN_MASK;
        cc_event->sl = sl;
        cc_event->svc_type = svc_type;
        cc_event->rlid = rlid;
        /* keep timestamp in units of 1.024 usec */
        cc_event->timestamp = ktime_get_ns() / 1024;

        spin_unlock_irqrestore(&ppd->cc_log_lock, flags);
}

void process_becn(struct hfi1_pportdata *ppd, u8 sl, u32 rlid, u32 lqpn,
                  u32 rqpn, u8 svc_type)
{
        struct cca_timer *cca_timer;
        u16 ccti, ccti_incr, ccti_timer, ccti_limit;
        u8 trigger_threshold;
        struct cc_state *cc_state;
        unsigned long flags;

        if (sl >= OPA_MAX_SLS)
                return;

        cc_state = get_cc_state(ppd);

        if (!cc_state)
                return;

        /*
         * 1) increase CCTI (for this SL)
         * 2) select IPG (i.e., call set_link_ipg())
         * 3) start timer
         */
        ccti_limit = cc_state->cct.ccti_limit;
        ccti_incr = cc_state->cong_setting.entries[sl].ccti_increase;
        ccti_timer = cc_state->cong_setting.entries[sl].ccti_timer;
        trigger_threshold =
                cc_state->cong_setting.entries[sl].trigger_threshold;

        spin_lock_irqsave(&ppd->cca_timer_lock, flags);

        cca_timer = &ppd->cca_timer[sl];
        if (cca_timer->ccti < ccti_limit) {
                if (cca_timer->ccti + ccti_incr <= ccti_limit)
                        cca_timer->ccti += ccti_incr;
                else
                        cca_timer->ccti = ccti_limit;
                set_link_ipg(ppd);
        }

        ccti = cca_timer->ccti;

        if (!hrtimer_active(&cca_timer->hrtimer)) {
                /* ccti_timer is in units of 1.024 usec */
                unsigned long nsec = 1024 * ccti_timer;

                hrtimer_start(&cca_timer->hrtimer, ns_to_ktime(nsec),
                              HRTIMER_MODE_REL_PINNED);
        }

        spin_unlock_irqrestore(&ppd->cca_timer_lock, flags);

        if ((trigger_threshold != 0) && (ccti >= trigger_threshold))
                log_cca_event(ppd, sl, rlid, lqpn, rqpn, svc_type);
}

/**
 * hfi1_rc_rcv - process an incoming RC packet
 * @packet: data packet information
 *
 * This is called from qp_rcv() to process an incoming RC packet
 * for the given QP.
 * May be called at interrupt level.
 */
void hfi1_rc_rcv(struct hfi1_packet *packet)
{
        struct hfi1_ctxtdata *rcd = packet->rcd;
        void *data = packet->payload;
        u32 tlen = packet->tlen;
        struct rvt_qp *qp = packet->qp;
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct hfi1_ibport *ibp = rcd_to_iport(rcd);
        struct ib_other_headers *ohdr = packet->ohdr;
        u32 opcode = packet->opcode;
        u32 hdrsize = packet->hlen;
        u32 psn = ib_bth_get_psn(packet->ohdr);
        u32 pad = packet->pad;
        struct ib_wc wc;
        u32 pmtu = qp->pmtu;
        int diff;
        struct ib_reth *reth;
        unsigned long flags;
        int ret;
        bool copy_last = false, fecn;
        u32 rkey;
        u8 extra_bytes = pad + packet->extra_byte + (SIZE_OF_CRC << 2);

        lockdep_assert_held(&qp->r_lock);

        if (hfi1_ruc_check_hdr(ibp, packet))
                return;

        fecn = process_ecn(qp, packet);
        opfn_trigger_conn_request(qp, be32_to_cpu(ohdr->bth[1]));

        /*
         * Process responses (ACKs) before anything else.  Note that the
         * packet sequence number will be for something in the send work
         * queue rather than the expected receive packet sequence number.
         * In other words, this QP is the requester.
         */
        if (opcode >= OP(RDMA_READ_RESPONSE_FIRST) &&
            opcode <= OP(ATOMIC_ACKNOWLEDGE)) {
                rc_rcv_resp(packet);
                return;
        }

        /* Compute 24 bits worth of difference. */
        diff = delta_psn(psn, qp->r_psn);
        if (unlikely(diff)) {
                if (rc_rcv_error(ohdr, data, qp, opcode, psn, diff, rcd))
                        return;
                goto send_ack;
        }

        /* Check for opcode sequence errors. */
        switch (qp->r_state) {
        case OP(SEND_FIRST):
        case OP(SEND_MIDDLE):
                if (opcode == OP(SEND_MIDDLE) ||
                    opcode == OP(SEND_LAST) ||
                    opcode == OP(SEND_LAST_WITH_IMMEDIATE) ||
                    opcode == OP(SEND_LAST_WITH_INVALIDATE))
                        break;
                goto nack_inv;

        case OP(RDMA_WRITE_FIRST):
        case OP(RDMA_WRITE_MIDDLE):
                if (opcode == OP(RDMA_WRITE_MIDDLE) ||
                    opcode == OP(RDMA_WRITE_LAST) ||
                    opcode == OP(RDMA_WRITE_LAST_WITH_IMMEDIATE))
                        break;
                goto nack_inv;

        default:
                if (opcode == OP(SEND_MIDDLE) ||
                    opcode == OP(SEND_LAST) ||
                    opcode == OP(SEND_LAST_WITH_IMMEDIATE) ||
                    opcode == OP(SEND_LAST_WITH_INVALIDATE) ||
                    opcode == OP(RDMA_WRITE_MIDDLE) ||
                    opcode == OP(RDMA_WRITE_LAST) ||
                    opcode == OP(RDMA_WRITE_LAST_WITH_IMMEDIATE))
                        goto nack_inv;
                /*
                 * Note that it is up to the requester to not send a new
                 * RDMA read or atomic operation before receiving an ACK
                 * for the previous operation.
                 */
                break;
        }

        if (qp->state == IB_QPS_RTR && !(qp->r_flags & RVT_R_COMM_EST))
                rvt_comm_est(qp);

        /* OK, process the packet. */
        switch (opcode) {
        case OP(SEND_FIRST):
                ret = rvt_get_rwqe(qp, false);
                if (ret < 0)
                        goto nack_op_err;
                if (!ret)
                        goto rnr_nak;
                qp->r_rcv_len = 0;
                /* FALLTHROUGH */
        case OP(SEND_MIDDLE):
        case OP(RDMA_WRITE_MIDDLE):
send_middle:
                /* Check for invalid length PMTU or posted rwqe len. */
                /*
                 * There will be no padding for 9B packet but 16B packets
                 * will come in with some padding since we always add
                 * CRC and LT bytes which will need to be flit aligned
                 */
                if (unlikely(tlen != (hdrsize + pmtu + extra_bytes)))
                        goto nack_inv;
                qp->r_rcv_len += pmtu;
                if (unlikely(qp->r_rcv_len > qp->r_len))
                        goto nack_inv;
                rvt_copy_sge(qp, &qp->r_sge, data, pmtu, true, false);
                break;

        case OP(RDMA_WRITE_LAST_WITH_IMMEDIATE):
                /* consume RWQE */
                ret = rvt_get_rwqe(qp, true);
                if (ret < 0)
                        goto nack_op_err;
                if (!ret)
                        goto rnr_nak;
                goto send_last_imm;

        case OP(SEND_ONLY):
        case OP(SEND_ONLY_WITH_IMMEDIATE):
        case OP(SEND_ONLY_WITH_INVALIDATE):
                ret = rvt_get_rwqe(qp, false);
                if (ret < 0)
                        goto nack_op_err;
                if (!ret)
                        goto rnr_nak;
                qp->r_rcv_len = 0;
                if (opcode == OP(SEND_ONLY))
                        goto no_immediate_data;
                if (opcode == OP(SEND_ONLY_WITH_INVALIDATE))
                        goto send_last_inv;
                /* FALLTHROUGH -- for SEND_ONLY_WITH_IMMEDIATE */
        case OP(SEND_LAST_WITH_IMMEDIATE):
send_last_imm:
                wc.ex.imm_data = ohdr->u.imm_data;
                wc.wc_flags = IB_WC_WITH_IMM;
                goto send_last;
        case OP(SEND_LAST_WITH_INVALIDATE):
send_last_inv:
                rkey = be32_to_cpu(ohdr->u.ieth);
                if (rvt_invalidate_rkey(qp, rkey))
                        goto no_immediate_data;
                wc.ex.invalidate_rkey = rkey;
                wc.wc_flags = IB_WC_WITH_INVALIDATE;
                goto send_last;
        case OP(RDMA_WRITE_LAST):
                copy_last = rvt_is_user_qp(qp);
                /* fall through */
        case OP(SEND_LAST):
no_immediate_data:
                wc.wc_flags = 0;
                wc.ex.imm_data = 0;
send_last:
                /* Check for invalid length. */
                /* LAST len should be >= 1 */
                if (unlikely(tlen < (hdrsize + extra_bytes)))
                        goto nack_inv;
                /* Don't count the CRC(and padding and LT byte for 16B). */
                tlen -= (hdrsize + extra_bytes);
                wc.byte_len = tlen + qp->r_rcv_len;
                if (unlikely(wc.byte_len > qp->r_len))
                        goto nack_inv;
                rvt_copy_sge(qp, &qp->r_sge, data, tlen, true, copy_last);
                rvt_put_ss(&qp->r_sge);
                qp->r_msn++;
                if (!__test_and_clear_bit(RVT_R_WRID_VALID, &qp->r_aflags))
                        break;
                wc.wr_id = qp->r_wr_id;
                wc.status = IB_WC_SUCCESS;
                if (opcode == OP(RDMA_WRITE_LAST_WITH_IMMEDIATE) ||
                    opcode == OP(RDMA_WRITE_ONLY_WITH_IMMEDIATE))
                        wc.opcode = IB_WC_RECV_RDMA_WITH_IMM;
                else
                        wc.opcode = IB_WC_RECV;
                wc.qp = &qp->ibqp;
                wc.src_qp = qp->remote_qpn;
                wc.slid = rdma_ah_get_dlid(&qp->remote_ah_attr) & U16_MAX;
                /*
                 * It seems that IB mandates the presence of an SL in a
                 * work completion only for the UD transport (see section
                 * 11.4.2 of IBTA Vol. 1).
                 *
                 * However, the way the SL is chosen below is consistent
                 * with the way that IB/qib works and is trying avoid
                 * introducing incompatibilities.
                 *
                 * See also OPA Vol. 1, section 9.7.6, and table 9-17.