// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
/*
 * Copyright (c) 2016 Mellanox Technologies Ltd. All rights reserved.
 * Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.
 */

#include <linux/skbuff.h>

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

static char *resp_state_name[] = {
        [RESPST_NONE]                           = "NONE",
        [RESPST_GET_REQ]                        = "GET_REQ",
        [RESPST_CHK_PSN]                        = "CHK_PSN",
        [RESPST_CHK_OP_SEQ]                     = "CHK_OP_SEQ",
        [RESPST_CHK_OP_VALID]                   = "CHK_OP_VALID",
        [RESPST_CHK_RESOURCE]                   = "CHK_RESOURCE",
        [RESPST_CHK_LENGTH]                     = "CHK_LENGTH",
        [RESPST_CHK_RKEY]                       = "CHK_RKEY",
        [RESPST_EXECUTE]                        = "EXECUTE",
        [RESPST_READ_REPLY]                     = "READ_REPLY",
        [RESPST_ATOMIC_REPLY]                   = "ATOMIC_REPLY",
        [RESPST_ATOMIC_WRITE_REPLY]             = "ATOMIC_WRITE_REPLY",
        [RESPST_PROCESS_FLUSH]                  = "PROCESS_FLUSH",
        [RESPST_COMPLETE]                       = "COMPLETE",
        [RESPST_ACKNOWLEDGE]                    = "ACKNOWLEDGE",
        [RESPST_CLEANUP]                        = "CLEANUP",
        [RESPST_DUPLICATE_REQUEST]              = "DUPLICATE_REQUEST",
        [RESPST_ERR_MALFORMED_WQE]              = "ERR_MALFORMED_WQE",
        [RESPST_ERR_UNSUPPORTED_OPCODE]         = "ERR_UNSUPPORTED_OPCODE",
        [RESPST_ERR_MISALIGNED_ATOMIC]          = "ERR_MISALIGNED_ATOMIC",
        [RESPST_ERR_PSN_OUT_OF_SEQ]             = "ERR_PSN_OUT_OF_SEQ",
        [RESPST_ERR_MISSING_OPCODE_FIRST]       = "ERR_MISSING_OPCODE_FIRST",
        [RESPST_ERR_MISSING_OPCODE_LAST_C]      = "ERR_MISSING_OPCODE_LAST_C",
        [RESPST_ERR_MISSING_OPCODE_LAST_D1E]    = "ERR_MISSING_OPCODE_LAST_D1E",
        [RESPST_ERR_TOO_MANY_RDMA_ATM_REQ]      = "ERR_TOO_MANY_RDMA_ATM_REQ",
        [RESPST_ERR_RNR]                        = "ERR_RNR",
        [RESPST_ERR_RKEY_VIOLATION]             = "ERR_RKEY_VIOLATION",
        [RESPST_ERR_INVALIDATE_RKEY]            = "ERR_INVALIDATE_RKEY_VIOLATION",
        [RESPST_ERR_LENGTH]                     = "ERR_LENGTH",
        [RESPST_ERR_CQ_OVERFLOW]                = "ERR_CQ_OVERFLOW",
        [RESPST_ERROR]                          = "ERROR",
        [RESPST_DONE]                           = "DONE",
        [RESPST_EXIT]                           = "EXIT",
};

/* rxe_recv calls here to add a request packet to the input queue */
void rxe_resp_queue_pkt(struct rxe_qp *qp, struct sk_buff *skb)
{
        skb_queue_tail(&qp->req_pkts, skb);
        rxe_sched_task(&qp->recv_task);
}

static inline enum resp_states get_req(struct rxe_qp *qp,
                                       struct rxe_pkt_info **pkt_p)
{
        struct sk_buff *skb;

        skb = skb_peek(&qp->req_pkts);
        if (!skb)
                return RESPST_EXIT;

        *pkt_p = SKB_TO_PKT(skb);

        return (qp->resp.res) ? RESPST_READ_REPLY : RESPST_CHK_PSN;
}

static enum resp_states check_psn(struct rxe_qp *qp,
                                  struct rxe_pkt_info *pkt)
{
        int diff = psn_compare(pkt->psn, qp->resp.psn);
        struct rxe_dev *rxe = to_rdev(qp->ibqp.device);

        switch (qp_type(qp)) {
        case IB_QPT_RC:
                if (diff > 0) {
                        if (qp->resp.sent_psn_nak)
                                return RESPST_CLEANUP;

                        qp->resp.sent_psn_nak = 1;
                        rxe_counter_inc(rxe, RXE_CNT_OUT_OF_SEQ_REQ);
                        return RESPST_ERR_PSN_OUT_OF_SEQ;

                } else if (diff < 0) {
                        rxe_counter_inc(rxe, RXE_CNT_DUP_REQ);
                        return RESPST_DUPLICATE_REQUEST;
                }

                if (qp->resp.sent_psn_nak)
                        qp->resp.sent_psn_nak = 0;

                break;

        case IB_QPT_UC:
                if (qp->resp.drop_msg || diff != 0) {
                        if (pkt->mask & RXE_START_MASK) {
                                qp->resp.drop_msg = 0;
                                return RESPST_CHK_OP_SEQ;
                        }

                        qp->resp.drop_msg = 1;
                        return RESPST_CLEANUP;
                }
                break;
        default:
                break;
        }

        return RESPST_CHK_OP_SEQ;
}

static enum resp_states check_op_seq(struct rxe_qp *qp,
                                     struct rxe_pkt_info *pkt)
{
        switch (qp_type(qp)) {
        case IB_QPT_RC:
                switch (qp->resp.opcode) {
                case IB_OPCODE_RC_SEND_FIRST:
                case IB_OPCODE_RC_SEND_MIDDLE:
                        switch (pkt->opcode) {
                        case IB_OPCODE_RC_SEND_MIDDLE:
                        case IB_OPCODE_RC_SEND_LAST:
                        case IB_OPCODE_RC_SEND_LAST_WITH_IMMEDIATE:
                        case IB_OPCODE_RC_SEND_LAST_WITH_INVALIDATE:
                                return RESPST_CHK_OP_VALID;
                        default:
                                return RESPST_ERR_MISSING_OPCODE_LAST_C;
                        }

                case IB_OPCODE_RC_RDMA_WRITE_FIRST:
                case IB_OPCODE_RC_RDMA_WRITE_MIDDLE:
                        switch (pkt->opcode) {
                        case IB_OPCODE_RC_RDMA_WRITE_MIDDLE:
                        case IB_OPCODE_RC_RDMA_WRITE_LAST:
                        case IB_OPCODE_RC_RDMA_WRITE_LAST_WITH_IMMEDIATE:
                                return RESPST_CHK_OP_VALID;
                        default:
                                return RESPST_ERR_MISSING_OPCODE_LAST_C;
                        }

                default:
                        switch (pkt->opcode) {
                        case IB_OPCODE_RC_SEND_MIDDLE:
                        case IB_OPCODE_RC_SEND_LAST:
                        case IB_OPCODE_RC_SEND_LAST_WITH_IMMEDIATE:
                        case IB_OPCODE_RC_SEND_LAST_WITH_INVALIDATE:
                        case IB_OPCODE_RC_RDMA_WRITE_MIDDLE:
                        case IB_OPCODE_RC_RDMA_WRITE_LAST:
                        case IB_OPCODE_RC_RDMA_WRITE_LAST_WITH_IMMEDIATE:
                                return RESPST_ERR_MISSING_OPCODE_FIRST;
                        default:
                                return RESPST_CHK_OP_VALID;
                        }
                }
                break;

        case IB_QPT_UC:
                switch (qp->resp.opcode) {
                case IB_OPCODE_UC_SEND_FIRST:
                case IB_OPCODE_UC_SEND_MIDDLE:
                        switch (pkt->opcode) {
                        case IB_OPCODE_UC_SEND_MIDDLE:
                        case IB_OPCODE_UC_SEND_LAST:
                        case IB_OPCODE_UC_SEND_LAST_WITH_IMMEDIATE:
                                return RESPST_CHK_OP_VALID;
                        default:
                                return RESPST_ERR_MISSING_OPCODE_LAST_D1E;
                        }

                case IB_OPCODE_UC_RDMA_WRITE_FIRST:
                case IB_OPCODE_UC_RDMA_WRITE_MIDDLE:
                        switch (pkt->opcode) {
                        case IB_OPCODE_UC_RDMA_WRITE_MIDDLE:
                        case IB_OPCODE_UC_RDMA_WRITE_LAST:
                        case IB_OPCODE_UC_RDMA_WRITE_LAST_WITH_IMMEDIATE:
                                return RESPST_CHK_OP_VALID;
                        default:
                                return RESPST_ERR_MISSING_OPCODE_LAST_D1E;
                        }

                default:
                        switch (pkt->opcode) {
                        case IB_OPCODE_UC_SEND_MIDDLE:
                        case IB_OPCODE_UC_SEND_LAST:
                        case IB_OPCODE_UC_SEND_LAST_WITH_IMMEDIATE:
                        case IB_OPCODE_UC_RDMA_WRITE_MIDDLE:
                        case IB_OPCODE_UC_RDMA_WRITE_LAST:
                        case IB_OPCODE_UC_RDMA_WRITE_LAST_WITH_IMMEDIATE:
                                qp->resp.drop_msg = 1;
                                return RESPST_CLEANUP;
                        default:
                                return RESPST_CHK_OP_VALID;
                        }
                }
                break;

        default:
                return RESPST_CHK_OP_VALID;
        }
}

static bool check_qp_attr_access(struct rxe_qp *qp,
                                 struct rxe_pkt_info *pkt)
{
        if (((pkt->mask & RXE_READ_MASK) &&
             !(qp->attr.qp_access_flags & IB_ACCESS_REMOTE_READ)) ||
            ((pkt->mask & (RXE_WRITE_MASK | RXE_ATOMIC_WRITE_MASK)) &&
             !(qp->attr.qp_access_flags & IB_ACCESS_REMOTE_WRITE)) ||
            ((pkt->mask & RXE_ATOMIC_MASK) &&
             !(qp->attr.qp_access_flags & IB_ACCESS_REMOTE_ATOMIC)))
                return false;

        if (pkt->mask & RXE_FLUSH_MASK) {
                u32 flush_type = feth_plt(pkt);

                if ((flush_type & IB_FLUSH_GLOBAL &&
                     !(qp->attr.qp_access_flags & IB_ACCESS_FLUSH_GLOBAL)) ||
                    (flush_type & IB_FLUSH_PERSISTENT &&
                     !(qp->attr.qp_access_flags & IB_ACCESS_FLUSH_PERSISTENT)))
                        return false;
        }

        return true;
}

static enum resp_states check_op_valid(struct rxe_qp *qp,
                                       struct rxe_pkt_info *pkt)
{
        switch (qp_type(qp)) {
        case IB_QPT_RC:
                if (!check_qp_attr_access(qp, pkt))
                        return RESPST_ERR_UNSUPPORTED_OPCODE;

                break;

        case IB_QPT_UC:
                if ((pkt->mask & RXE_WRITE_MASK) &&
                    !(qp->attr.qp_access_flags & IB_ACCESS_REMOTE_WRITE)) {
                        qp->resp.drop_msg = 1;
                        return RESPST_CLEANUP;
                }

                break;

        case IB_QPT_UD:
        case IB_QPT_GSI:
                break;

        default:
                WARN_ON_ONCE(1);
                break;
        }

        return RESPST_CHK_RESOURCE;
}

static enum resp_states get_srq_wqe(struct rxe_qp *qp)
{
        struct rxe_srq *srq = qp->srq;
        struct rxe_queue *q = srq->rq.queue;
        struct rxe_recv_wqe *wqe;
        struct ib_event ev;
        unsigned int count;
        size_t size;
        unsigned long flags;

        if (srq->error)
                return RESPST_ERR_RNR;

        spin_lock_irqsave(&srq->rq.consumer_lock, flags);

        wqe = queue_head(q, QUEUE_TYPE_FROM_CLIENT);
        if (!wqe) {
                spin_unlock_irqrestore(&srq->rq.consumer_lock, flags);
                return RESPST_ERR_RNR;
        }

        /* don't trust user space data */
        if (unlikely(wqe->dma.num_sge > srq->rq.max_sge)) {
                spin_unlock_irqrestore(&srq->rq.consumer_lock, flags);
                rxe_dbg_qp(qp, "invalid num_sge in SRQ entry\n");
                return RESPST_ERR_MALFORMED_WQE;
        }
        size = sizeof(*wqe) + wqe->dma.num_sge*sizeof(struct rxe_sge);
        memcpy(&qp->resp.srq_wqe, wqe, size);

        qp->resp.wqe = &qp->resp.srq_wqe.wqe;
        queue_advance_consumer(q, QUEUE_TYPE_FROM_CLIENT);
        count = queue_count(q, QUEUE_TYPE_FROM_CLIENT);

        if (srq->limit && srq->ibsrq.event_handler && (count < srq->limit)) {
                srq->limit = 0;
                goto event;
        }

        spin_unlock_irqrestore(&srq->rq.consumer_lock, flags);
        return RESPST_CHK_LENGTH;

event:
        spin_unlock_irqrestore(&srq->rq.consumer_lock, flags);
        ev.device = qp->ibqp.device;
        ev.element.srq = qp->ibqp.srq;
        ev.event = IB_EVENT_SRQ_LIMIT_REACHED;
        srq->ibsrq.event_handler(&ev, srq->ibsrq.srq_context);
        return RESPST_CHK_LENGTH;
}

static enum resp_states check_resource(struct rxe_qp *qp,
                                       struct rxe_pkt_info *pkt)
{
        struct rxe_srq *srq = qp->srq;

        if (pkt->mask & (RXE_READ_OR_ATOMIC_MASK | RXE_ATOMIC_WRITE_MASK)) {
                /* it is the requesters job to not send
                 * too many read/atomic ops, we just
                 * recycle the responder resource queue
                 */
                if (likely(qp->attr.max_dest_rd_atomic > 0))
                        return RESPST_CHK_LENGTH;
                else
                        return RESPST_ERR_TOO_MANY_RDMA_ATM_REQ;
        }

        if (pkt->mask & RXE_RWR_MASK) {
                if (srq)
                        return get_srq_wqe(qp);

                qp->resp.wqe = queue_head(qp->rq.queue,
                                QUEUE_TYPE_FROM_CLIENT);
                return (qp->resp.wqe) ? RESPST_CHK_LENGTH : RESPST_ERR_RNR;
        }

        return RESPST_CHK_LENGTH;
}

static enum resp_states rxe_resp_check_length(struct rxe_qp *qp,
                                              struct rxe_pkt_info *pkt)
{
        /*
         * See IBA C9-92
         * For UD QPs we only check if the packet will fit in the
         * receive buffer later. For RDMA operations additional
         * length checks are performed in check_rkey.
         */
        if ((qp_type(qp) == IB_QPT_GSI) || (qp_type(qp) == IB_QPT_UD)) {
                unsigned int payload = payload_size(pkt);
                unsigned int recv_buffer_len = 0;
                int i;

                for (i = 0; i < qp->resp.wqe->dma.num_sge; i++)
                        recv_buffer_len += qp->resp.wqe->dma.sge[i].length;
                if (payload + sizeof(union rdma_network_hdr) > recv_buffer_len) {
                        rxe_dbg_qp(qp, "The receive buffer is too small for this UD packet.\n");
                        return RESPST_ERR_LENGTH;
                }
        }

        if (pkt->mask & RXE_PAYLOAD_MASK && ((qp_type(qp) == IB_QPT_RC) ||
                                             (qp_type(qp) == IB_QPT_UC))) {
                unsigned int mtu = qp->mtu;
                unsigned int payload = payload_size(pkt);

                if ((pkt->mask & RXE_START_MASK) &&
                    (pkt->mask & RXE_END_MASK)) {
                        if (unlikely(payload > mtu)) {
                                rxe_dbg_qp(qp, "only packet too long\n");
                                return RESPST_ERR_LENGTH;
                        }
                } else if ((pkt->mask & RXE_START_MASK) ||
                           (pkt->mask & RXE_MIDDLE_MASK)) {
                        if (unlikely(payload != mtu)) {
                                rxe_dbg_qp(qp, "first or middle packet not mtu\n");
                                return RESPST_ERR_LENGTH;
                        }
                } else if (pkt->mask & RXE_END_MASK) {
                        if (unlikely((payload == 0) || (payload > mtu))) {
                                rxe_dbg_qp(qp, "last packet zero or too long\n");
                                return RESPST_ERR_LENGTH;
                        }
                }
        }

        /* See IBA C9-94 */
        if (pkt->mask & RXE_RETH_MASK) {
                if (reth_len(pkt) > (1U << 31)) {
                        rxe_dbg_qp(qp, "dma length too long\n");
                        return RESPST_ERR_LENGTH;
                }
        }

        if (pkt->mask & RXE_RDMA_OP_MASK)
                return RESPST_CHK_RKEY;
        else
                return RESPST_EXECUTE;
}

/* if the reth length field is zero we can assume nothing
 * about the rkey value and should not validate or use it.
 * Instead set qp->resp.rkey to 0 which is an invalid rkey
 * value since the minimum index part is 1.
 */
static void qp_resp_from_reth(struct rxe_qp *qp, struct rxe_pkt_info *pkt)
{
        unsigned int length = reth_len(pkt);

        qp->resp.va = reth_va(pkt);
        qp->resp.offset = 0;
        qp->resp.resid = length;
        qp->resp.length = length;
        if (pkt->mask & RXE_READ_OR_WRITE_MASK && length == 0)
                qp->resp.rkey = 0;
        else
                qp->resp.rkey = reth_rkey(pkt);
}

static void qp_resp_from_atmeth(struct rxe_qp *qp, struct rxe_pkt_info *pkt)
{
        qp->resp.va = atmeth_va(pkt);
        qp->resp.offset = 0;
        qp->resp.rkey = atmeth_rkey(pkt);
        qp->resp.resid = sizeof(u64);
}

/* resolve the packet rkey to qp->resp.mr or set qp->resp.mr to NULL
 * if an invalid rkey is received or the rdma length is zero. For middle
 * or last packets use the stored value of mr.
 */
static enum resp_states check_rkey(struct rxe_qp *qp,
                                   struct rxe_pkt_info *pkt)
{
        struct rxe_mr *mr = NULL;
        struct rxe_mw *mw = NULL;
        u64 va;
        u32 rkey;
        u32 resid;
        u32 pktlen;
        int mtu = qp->mtu;
        enum resp_states state;
        int access = 0;

        /* parse RETH or ATMETH header for first/only packets
         * for va, length, rkey, etc. or use current value for
         * middle/last packets.
         */
        if (pkt->mask & (RXE_READ_OR_WRITE_MASK | RXE_ATOMIC_WRITE_MASK)) {
                if (pkt->mask & RXE_RETH_MASK)
                        qp_resp_from_reth(qp, pkt);

                access = (pkt->mask & RXE_READ_MASK) ? IB_ACCESS_REMOTE_READ
                                                     : IB_ACCESS_REMOTE_WRITE;
        } else if (pkt->mask & RXE_FLUSH_MASK) {
                u32 flush_type = feth_plt(pkt);

                if (pkt->mask & RXE_RETH_MASK)
                        qp_resp_from_reth(qp, pkt);

                if (flush_type & IB_FLUSH_GLOBAL)
                        access |= IB_ACCESS_FLUSH_GLOBAL;
                if (flush_type & IB_FLUSH_PERSISTENT)
                        access |= IB_ACCESS_FLUSH_PERSISTENT;
        } else if (pkt->mask & RXE_ATOMIC_MASK) {
                qp_resp_from_atmeth(qp, pkt);
                access = IB_ACCESS_REMOTE_ATOMIC;
        } else {
                /* shouldn't happen */
                WARN_ON(1);
        }

        /* A zero-byte read or write op is not required to
         * set an addr or rkey. See C9-88
         */
        if ((pkt->mask & RXE_READ_OR_WRITE_MASK) &&
            (pkt->mask & RXE_RETH_MASK) && reth_len(pkt) == 0) {
                qp->resp.mr = NULL;
                return RESPST_EXECUTE;
        }

        va      = qp->resp.va;
        rkey    = qp->resp.rkey;
        resid   = qp->resp.resid;
        pktlen  = payload_size(pkt);

        if (rkey_is_mw(rkey)) {
                mw = rxe_lookup_mw(qp, access, rkey);
                if (!mw) {
                        rxe_dbg_qp(qp, "no MW matches rkey %#x\n", rkey);
                        state = RESPST_ERR_RKEY_VIOLATION;
                        goto err;
                }

                mr = mw->mr;
                if (!mr) {
                        rxe_dbg_qp(qp, "MW doesn't have an MR\n");
                        state = RESPST_ERR_RKEY_VIOLATION;
                        goto err;
                }

                if (mw->access & IB_ZERO_BASED)
                        qp->resp.offset = mw->addr;

                rxe_get(mr);
                rxe_put(mw);
                mw = NULL;
        } else {
                mr = lookup_mr(qp->pd, access, rkey, RXE_LOOKUP_REMOTE);
                if (!mr) {
                        rxe_dbg_qp(qp, "no MR matches rkey %#x\n", rkey);
                        state = RESPST_ERR_RKEY_VIOLATION;
                        goto err;
                }
        }

        if (pkt->mask & RXE_FLUSH_MASK) {
                /* FLUSH MR may not set va or resid
                 * no need to check range since we will flush whole mr
                 */
                if (feth_sel(pkt) == IB_FLUSH_MR)
                        goto skip_check_range;
        }

        if (mr_check_range(mr, va + qp->resp.offset, resid)) {
                state = RESPST_ERR_RKEY_VIOLATION;
                goto err;
        }

skip_check_range:
        if (pkt->mask & (RXE_WRITE_MASK | RXE_ATOMIC_WRITE_MASK)) {
                if (resid > mtu) {
                        if (pktlen != mtu || bth_pad(pkt)) {
                                state = RESPST_ERR_LENGTH;
                                goto err;
                        }
                } else {
                        if (pktlen != resid) {
                                state = RESPST_ERR_LENGTH;
                                goto err;
                        }
                        if ((bth_pad(pkt) != (0x3 & (-resid)))) {
                                /* This case may not be exactly that
                                 * but nothing else fits.
                                 */
                                state = RESPST_ERR_LENGTH;
                                goto err;
                        }
                }
        }

        WARN_ON_ONCE(qp->resp.mr);

        qp->resp.mr = mr;
        return RESPST_EXECUTE;

err:
        qp->resp.mr = NULL;
        if (mr)
                rxe_put(mr);
        if (mw)
                rxe_put(mw);

        return state;
}

static enum resp_states send_data_in(struct rxe_qp *qp, void *data_addr,
                                     int data_len)
{
        int err;

        err = copy_data(qp->pd, IB_ACCESS_LOCAL_WRITE, &qp->resp.wqe->dma,
                        data_addr, data_len, RXE_TO_MR_OBJ);
        if (unlikely(err))
                return (err == -ENOSPC) ? RESPST_ERR_LENGTH
                                        : RESPST_ERR_MALFORMED_WQE;

        return RESPST_NONE;
}

static enum resp_states write_data_in(struct rxe_qp *qp,
                                      struct rxe_pkt_info *pkt)
{
        enum resp_states rc = RESPST_NONE;
        int     err;
        int data_len = payload_size(pkt);

        err = rxe_mr_copy(qp->resp.mr, qp->resp.va + qp->resp.offset,
                          payload_addr(pkt), data_len, RXE_TO_MR_OBJ);
        if (err) {
                rc = RESPST_ERR_RKEY_VIOLATION;
                goto out;
        }

        qp->resp.va += data_len;
        qp->resp.resid -= data_len;

out:
        return rc;
}

static struct resp_res *rxe_prepare_res(struct rxe_qp *qp,
                                        struct rxe_pkt_info *pkt,
                                        int type)
{
        struct resp_res *res;
        u32 pkts;

        res = &qp->resp.resources[qp->resp.res_head];
        rxe_advance_resp_resource(qp);
        free_rd_atomic_resource(res);

        res->type = type;
        res->replay = 0;

        switch (type) {
        case RXE_READ_MASK:
                res->read.va = qp->resp.va + qp->resp.offset;
                res->read.va_org = qp->resp.va + qp->resp.offset;
                res->read.resid = qp->resp.resid;
                res->read.length = qp->resp.resid;
                res->read.rkey = qp->resp.rkey;

                pkts = max_t(u32, (reth_len(pkt) + qp->mtu - 1)/qp->mtu, 1);
                res->first_psn = pkt->psn;
                res->cur_psn = pkt->psn;
                res->last_psn = (pkt->psn + pkts - 1) & BTH_PSN_MASK;

                res->state = rdatm_res_state_new;
                break;
        case RXE_ATOMIC_MASK:
        case RXE_ATOMIC_WRITE_MASK:
                res->first_psn = pkt->psn;
                res->last_psn = pkt->psn;
                res->cur_psn = pkt->psn;
                break;
        case RXE_FLUSH_MASK:
                res->flush.va = qp->resp.va + qp->resp.offset;
                res->flush.length = qp->resp.length;
                res->flush.type = feth_plt(pkt);
                res->flush.level = feth_sel(pkt);
        }

        return res;
}

static enum resp_states process_flush(struct rxe_qp *qp,
                                       struct rxe_pkt_info *pkt)
{
        u64 length, start;
        struct rxe_mr *mr = qp->resp.mr;
        struct resp_res *res = qp->resp.res;

        /* oA19-14, oA19-15 */
        if (res && res->replay)
                return RESPST_ACKNOWLEDGE;
        else if (!res) {
                res = rxe_prepare_res(qp, pkt, RXE_FLUSH_MASK);
                qp->resp.res = res;
        }

        if (res->flush.level == IB_FLUSH_RANGE) {
                start = res->flush.va;
                length = res->flush.length;
        } else { /* level == IB_FLUSH_MR */
                start = mr->ibmr.iova;
                length = mr->ibmr.length;
        }

        if (res->flush.type & IB_FLUSH_PERSISTENT) {
                if (rxe_flush_pmem_iova(mr, start, length))
                        return RESPST_ERR_RKEY_VIOLATION;
                /* Make data persistent. */
                wmb();
        } else if (res->flush.type & IB_FLUSH_GLOBAL) {
                /* Make data global visibility. */
                wmb();
        }

        qp->resp.msn++;

        /* next expected psn, read handles this separately */
        qp->resp.psn = (pkt->psn + 1) & BTH_PSN_MASK;
        qp->resp.ack_psn = qp->resp.psn;

        qp->resp.opcode = pkt->opcode;
        qp->resp.status = IB_WC_SUCCESS;

        return RESPST_ACKNOWLEDGE;
}

static enum resp_states atomic_reply(struct rxe_qp *qp,
                                     struct rxe_pkt_info *pkt)
{
        struct rxe_mr *mr = qp->resp.mr;
        struct resp_res *res = qp->resp.res;
        int err;

        if (!res) {
                res = rxe_prepare_res(qp, pkt, RXE_ATOMIC_MASK);
                qp->resp.res = res;
        }

        if (!res->replay) {
                u64 iova = qp->resp.va + qp->resp.offset;

                if (is_odp_mr(mr))
                        err = rxe_odp_atomic_op(mr, iova, pkt->opcode,
                                                atmeth_comp(pkt),
                                                atmeth_swap_add(pkt),
                                                &res->atomic.orig_val);
                else
                        err = rxe_mr_do_atomic_op(mr, iova, pkt->opcode,
                                                  atmeth_comp(pkt),
                                                  atmeth_swap_add(pkt),
                                                  &res->atomic.orig_val);
                if (err)
                        return err;

                qp->resp.msn++;

                /* next expected psn, read handles this separately */
                qp->resp.psn = (pkt->psn + 1) & BTH_PSN_MASK;
                qp->resp.ack_psn = qp->resp.psn;

                qp->resp.opcode = pkt->opcode;
                qp->resp.status = IB_WC_SUCCESS;
        }

        return RESPST_ACKNOWLEDGE;
}

static enum resp_states atomic_write_reply(struct rxe_qp *qp,
                                           struct rxe_pkt_info *pkt)
{
        struct resp_res *res = qp->resp.res;
        struct rxe_mr *mr;
        u64 value;
        u64 iova;
        int err;

        if (!res) {
                res = rxe_prepare_res(qp, pkt, RXE_ATOMIC_WRITE_MASK);
                qp->resp.res = res;
        }

        if (res->replay)
                return RESPST_ACKNOWLEDGE;

        mr = qp->resp.mr;
        value = *(u64 *)payload_addr(pkt);
        iova = qp->resp.va + qp->resp.offset;

        /* See IBA oA19-28 */
        if (unlikely(mr->state != RXE_MR_STATE_VALID)) {
                rxe_dbg_mr(mr, "mr not in valid state\n");
                return RESPST_ERR_RKEY_VIOLATION;
        }

        if (is_odp_mr(mr))
                err = rxe_odp_do_atomic_write(mr, iova, value);
        else
                err = rxe_mr_do_atomic_write(mr, iova, value);
        if (err)
                return err;

        qp->resp.resid = 0;
        qp->resp.msn++;

        /* next expected psn, read handles this separately */
        qp->resp.psn = (pkt->psn + 1) & BTH_PSN_MASK;
        qp->resp.ack_psn = qp->resp.psn;

        qp->resp.opcode = pkt->opcode;
        qp->resp.status = IB_WC_SUCCESS;

        return RESPST_ACKNOWLEDGE;
}

static struct sk_buff *prepare_ack_packet(struct rxe_qp *qp,
                                          struct rxe_pkt_info *ack,
                                          int opcode,
                                          int payload,
                                          u32 psn,
                                          u8 syndrome)
{
        struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
        struct sk_buff *skb;
        int paylen;
        int pad;
        int err;

        /*
         * allocate packet
         */
        pad = (-payload) & 0x3;
        paylen = rxe_opcode[opcode].length + payload + pad + RXE_ICRC_SIZE;

        skb = rxe_init_packet(rxe, &qp->pri_av, paylen, ack);
        if (!skb)
                return NULL;

        ack->qp = qp;
        ack->opcode = opcode;
        ack->mask = rxe_opcode[opcode].mask;
        ack->paylen = paylen;
        ack->psn = psn;

        bth_init(ack, opcode, 0, 0, pad, IB_DEFAULT_PKEY_FULL,
                 qp->attr.dest_qp_num, 0, psn);

        if (ack->mask & RXE_AETH_MASK) {
                aeth_set_syn(ack, syndrome);
                aeth_set_msn(ack, qp->resp.msn);
        }

        if (ack->mask & RXE_ATMACK_MASK)
                atmack_set_orig(ack, qp->resp.res->atomic.orig_val);

        err = rxe_prepare(&qp->pri_av, ack, skb);
        if (err) {
                kfree_skb(skb);
                return NULL;
        }

        return skb;
}

/**
 * rxe_recheck_mr - revalidate MR from rkey and get a reference
 * @qp: the qp
 * @rkey: the rkey
 *
 * This code allows the MR to be invalidated or deregistered or
 * the MW if one was used to be invalidated or deallocated.
 * It is assumed that the access permissions if originally good
 * are OK and the mappings to be unchanged.
 *
 * TODO: If someone reregisters an MR to change its size or
 * access permissions during the processing of an RDMA read
 * we should kill the responder resource and complete the
 * operation with an error.
 *
 * Return: mr on success else NULL
 */
static struct rxe_mr *rxe_recheck_mr(struct rxe_qp *qp, u32 rkey)
{
        struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
        struct rxe_mr *mr;
        struct rxe_mw *mw;

        if (rkey_is_mw(rkey)) {
                mw = rxe_pool_get_index(&rxe->mw_pool, rkey >> 8);
                if (!mw)
                        return NULL;

                mr = mw->mr;
                if (mw->rkey != rkey || mw->state != RXE_MW_STATE_VALID ||
                    !mr || mr->state != RXE_MR_STATE_VALID) {
                        rxe_put(mw);
                        return NULL;
                }

                rxe_get(mr);
                rxe_put(mw);

                return mr;
        }

        mr = rxe_pool_get_index(&rxe->mr_pool, rkey >> 8);
        if (!mr)
                return NULL;

        if (mr->rkey != rkey || mr->state != RXE_MR_STATE_VALID) {
                rxe_put(mr);
                return NULL;
        }

        return mr;
}

/* RDMA read response. If res is not NULL, then we have a current RDMA request
 * being processed or replayed.
 */
static enum resp_states read_reply(struct rxe_qp *qp,
                                   struct rxe_pkt_info *req_pkt)
{
        struct rxe_pkt_info ack_pkt;
        struct sk_buff *skb;
        int mtu = qp->mtu;
        enum resp_states state;
        int payload;
        int opcode;
        int err;
        struct resp_res *res = qp->resp.res;
        struct rxe_mr *mr;

        if (!res) {
                res = rxe_prepare_res(qp, req_pkt, RXE_READ_MASK);
                qp->resp.res = res;
        }

        if (res->state == rdatm_res_state_new) {
                if (!res->replay || qp->resp.length == 0) {
                        /* if length == 0 mr will be NULL (is ok)
                         * otherwise qp->resp.mr holds a ref on mr
                         * which we transfer to mr and drop below.
                         */
                        mr = qp->resp.mr;
                        qp->resp.mr = NULL;
                } else {
                        mr = rxe_recheck_mr(qp, res->read.rkey);
                        if (!mr)
                                return RESPST_ERR_RKEY_VIOLATION;
                }

                if (res->read.resid <= mtu)
                        opcode = IB_OPCODE_RC_RDMA_READ_RESPONSE_ONLY;
                else
                        opcode = IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST;
        } else {
                /* re-lookup mr from rkey on all later packets.
                 * length will be non-zero. This can fail if someone
                 * modifies or destroys the mr since the first packet.
                 */
                mr = rxe_recheck_mr(qp, res->read.rkey);
                if (!mr)
                        return RESPST_ERR_RKEY_VIOLATION;

                if (res->read.resid > mtu)
                        opcode = IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE;
                else
                        opcode = IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST;
        }

        res->state = rdatm_res_state_next;

        payload = min_t(int, res->read.resid, mtu);

        skb = prepare_ack_packet(qp, &ack_pkt, opcode, payload,
                                 res->cur_psn, AETH_ACK_UNLIMITED);
        if (!skb) {
                state = RESPST_ERR_RNR;
                goto err_out;
        }

        err = rxe_mr_copy(mr, res->read.va, payload_addr(&ack_pkt),
                          payload, RXE_FROM_MR_OBJ);
        if (err) {
                kfree_skb(skb);
                state = RESPST_ERR_RKEY_VIOLATION;
                goto err_out;
        }

        if (bth_pad(&ack_pkt)) {
                u8 *pad = payload_addr(&ack_pkt) + payload;

                memset(pad, 0, bth_pad(&ack_pkt));
        }

        /* rxe_xmit_packet always consumes the skb */
        err = rxe_xmit_packet(qp, &ack_pkt, skb);
        if (err) {
                state = RESPST_ERR_RNR;
                goto err_out;
        }

        res->read.va += payload;
        res->read.resid -= payload;
        res->cur_psn = (res->cur_psn + 1) & BTH_PSN_MASK;

        if (res->read.resid > 0) {
                state = RESPST_DONE;
        } else {
                qp->resp.res = NULL;
                if (!res->replay)
                        qp->resp.opcode = -1;
                if (psn_compare(res->cur_psn, qp->resp.psn) >= 0)
                        qp->resp.psn = res->cur_psn;
                state = RESPST_CLEANUP;
        }

err_out:
        if (mr)
                rxe_put(mr);
        return state;
}

static int invalidate_rkey(struct rxe_qp *qp, u32 rkey)
{
        if (rkey_is_mw(rkey))
                return rxe_invalidate_mw(qp, rkey);
        else
                return rxe_invalidate_mr(qp, rkey);
}

/* Executes a new request. A retried request never reach that function (send
 * and writes are discarded, and reads and atomics are retried elsewhere.
 */
static enum resp_states execute(struct rxe_qp *qp, struct rxe_pkt_info *pkt)
{
        enum resp_states err;
        struct sk_buff *skb = PKT_TO_SKB(pkt);
        union rdma_network_hdr hdr;

        if (pkt->mask & RXE_SEND_MASK) {
                if (qp_type(qp) == IB_QPT_UD ||
                    qp_type(qp) == IB_QPT_GSI) {
                        if (skb->protocol == htons(ETH_P_IP)) {
                                memset(&hdr.reserved, 0,
                                                sizeof(hdr.reserved));
                                memcpy(&hdr.roce4grh, ip_hdr(skb),
                                                sizeof(hdr.roce4grh));
                                err = send_data_in(qp, &hdr, sizeof(hdr));
                        } else {
                                err = send_data_in(qp, ipv6_hdr(skb),
                                                sizeof(hdr));
                        }
                        if (err)
                                return err;
                }
                err = send_data_in(qp, payload_addr(pkt), payload_size(pkt));
                if (err)
                        return err;
        } else if (pkt->mask & RXE_WRITE_MASK) {
                err = write_data_in(qp, pkt);
                if (err)
                        return err;
        } else if (pkt->mask & RXE_READ_MASK) {
                /* For RDMA Read we can increment the msn now. See C9-148. */
                qp->resp.msn++;
                return RESPST_READ_REPLY;
        } else if (pkt->mask & RXE_ATOMIC_MASK) {
                return RESPST_ATOMIC_REPLY;
        } else if (pkt->mask & RXE_ATOMIC_WRITE_MASK) {
                return RESPST_ATOMIC_WRITE_REPLY;
        } else if (pkt->mask & RXE_FLUSH_MASK) {
                return RESPST_PROCESS_FLUSH;
        } else {
                /* Unreachable */
                WARN_ON_ONCE(1);
        }

        if (pkt->mask & RXE_IETH_MASK) {
                u32 rkey = ieth_rkey(pkt);

                err = invalidate_rkey(qp, rkey);
                if (err)
                        return RESPST_ERR_INVALIDATE_RKEY;
        }

        if (pkt->mask & RXE_END_MASK)
                /* We successfully processed this new request. */
                qp->resp.msn++;

        /* next expected psn, read handles this separately */
        qp->resp.psn = (pkt->psn + 1) & BTH_PSN_MASK;
        qp->resp.ack_psn = qp->resp.psn;

        qp->resp.opcode = pkt->opcode;
        qp->resp.status = IB_WC_SUCCESS;

        if (pkt->mask & RXE_COMP_MASK)
                return RESPST_COMPLETE;
        else if (qp_type(qp) == IB_QPT_RC)
                return RESPST_ACKNOWLEDGE;
        else
                return RESPST_CLEANUP;
}

static enum resp_states do_complete(struct rxe_qp *qp,
                                    struct rxe_pkt_info *pkt)
{
        struct rxe_cqe cqe;
        struct ib_wc *wc = &cqe.ibwc;
        struct ib_uverbs_wc *uwc = &cqe.uibwc;
        struct rxe_recv_wqe *wqe = qp->resp.wqe;
        struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
        unsigned long flags;

        if (!wqe)
                goto finish;

        memset(&cqe, 0, sizeof(cqe));

        if (qp->rcq->is_user) {
                uwc->status             = qp->resp.status;
                uwc->qp_num             = qp->ibqp.qp_num;
                uwc->wr_id              = wqe->wr_id;
        } else {
                wc->status              = qp->resp.status;
                wc->qp                  = &qp->ibqp;
                wc->wr_id               = wqe->wr_id;
        }

        if (wc->status == IB_WC_SUCCESS) {
                rxe_counter_inc(rxe, RXE_CNT_RDMA_RECV);
                wc->opcode = (pkt->mask & RXE_IMMDT_MASK &&
                                pkt->mask & RXE_WRITE_MASK) ?
                                        IB_WC_RECV_RDMA_WITH_IMM : IB_WC_RECV;
                wc->byte_len = (pkt->mask & RXE_IMMDT_MASK &&
                                pkt->mask & RXE_WRITE_MASK) ?
                                        qp->resp.length : wqe->dma.length - wqe->dma.resid;

                /* fields after byte_len are different between kernel and user
                 * space
                 */
                if (qp->rcq->is_user) {
                        uwc->wc_flags = IB_WC_GRH;

                        if (pkt->mask & RXE_IMMDT_MASK) {
                                uwc->wc_flags |= IB_WC_WITH_IMM;
                                uwc->ex.imm_data = immdt_imm(pkt);
                        }

                        if (pkt->mask & RXE_IETH_MASK) {
                                uwc->wc_flags |= IB_WC_WITH_INVALIDATE;
                                uwc->ex.invalidate_rkey = ieth_rkey(pkt);
                        }

                        if (pkt->mask & RXE_DETH_MASK)
                                uwc->src_qp = deth_sqp(pkt);

                        uwc->port_num           = qp->attr.port_num;
                } else {
                        struct sk_buff *skb = PKT_TO_SKB(pkt);

                        wc->wc_flags = IB_WC_GRH | IB_WC_WITH_NETWORK_HDR_TYPE;
                        if (skb->protocol == htons(ETH_P_IP))
                                wc->network_hdr_type = RDMA_NETWORK_IPV4;
                        else
                                wc->network_hdr_type = RDMA_NETWORK_IPV6;

                        if (is_vlan_dev(skb->dev)) {
                                wc->wc_flags |= IB_WC_WITH_VLAN;
                                wc->vlan_id = vlan_dev_vlan_id(skb->dev);
                        }

                        if (pkt->mask & RXE_IMMDT_MASK) {
                                wc->wc_flags |= IB_WC_WITH_IMM;
                                wc->ex.imm_data = immdt_imm(pkt);
                        }

                        if (pkt->mask & RXE_IETH_MASK) {
                                wc->wc_flags |= IB_WC_WITH_INVALIDATE;
                                wc->ex.invalidate_rkey = ieth_rkey(pkt);
                        }

                        if (pkt->mask & RXE_DETH_MASK)
                                wc->src_qp = deth_sqp(pkt);

                        wc->port_num            = qp->attr.port_num;
                }
        } else {
                if (wc->status != IB_WC_WR_FLUSH_ERR)
                        rxe_err_qp(qp, "non-flush error status = %d\n",
                                wc->status);
        }

        /* have copy for srq and reference for !srq */
        if (!qp->srq)
                queue_advance_consumer(qp->rq.queue, QUEUE_TYPE_FROM_CLIENT);

        qp->resp.wqe = NULL;

        if (rxe_cq_post(qp->rcq, &cqe, pkt ? bth_se(pkt) : 1))
                return RESPST_ERR_CQ_OVERFLOW;

finish:
        spin_lock_irqsave(&qp->state_lock, flags);
        if (unlikely(qp_state(qp) == IB_QPS_ERR)) {
                spin_unlock_irqrestore(&qp->state_lock, flags);
                return RESPST_CHK_RESOURCE;
        }
        spin_unlock_irqrestore(&qp->state_lock, flags);

        if (unlikely(!pkt))
                return RESPST_DONE;
        if (qp_type(qp) == IB_QPT_RC)
                return RESPST_ACKNOWLEDGE;
        else
                return RESPST_CLEANUP;
}


static int send_common_ack(struct rxe_qp *qp, u8 syndrome, u32 psn,
                                  int opcode, const char *msg)
{
        int err;
        struct rxe_pkt_info ack_pkt;
        struct sk_buff *skb;

        skb = prepare_ack_packet(qp, &ack_pkt, opcode, 0, psn, syndrome);
        if (!skb)
                return -ENOMEM;

        err = rxe_xmit_packet(qp, &ack_pkt, skb);
        if (err)
                rxe_dbg_qp(qp, "Failed sending %s\n", msg);

        return err;
}

static int send_ack(struct rxe_qp *qp, u8 syndrome, u32 psn)
{
        return send_common_ack(qp, syndrome, psn,
                        IB_OPCODE_RC_ACKNOWLEDGE, "ACK");
}

static int send_atomic_ack(struct rxe_qp *qp, u8 syndrome, u32 psn)
{
        int ret = send_common_ack(qp, syndrome, psn,
                        IB_OPCODE_RC_ATOMIC_ACKNOWLEDGE, "ATOMIC ACK");

        /* have to clear this since it is used to trigger
         * long read replies
         */
        qp->resp.res = NULL;
        return ret;
}

static int send_read_response_ack(struct rxe_qp *qp, u8 syndrome, u32 psn)
{
        int ret = send_common_ack(qp, syndrome, psn,
                        IB_OPCODE_RC_RDMA_READ_RESPONSE_ONLY,
                        "RDMA READ response of length zero ACK");

        /* have to clear this since it is used to trigger
         * long read replies
         */
        qp->resp.res = NULL;
        return ret;
}

static enum resp_states acknowledge(struct rxe_qp *qp,
                                    struct rxe_pkt_info *pkt)
{
        if (qp_type(qp) != IB_QPT_RC)
                return RESPST_CLEANUP;

        if (qp->resp.aeth_syndrome != AETH_ACK_UNLIMITED)
                send_ack(qp, qp->resp.aeth_syndrome, pkt->psn);
        else if (pkt->mask & RXE_ATOMIC_MASK)
                send_atomic_ack(qp, AETH_ACK_UNLIMITED, pkt->psn);
        else if (pkt->mask & (RXE_FLUSH_MASK | RXE_ATOMIC_WRITE_MASK))
                send_read_response_ack(qp, AETH_ACK_UNLIMITED, pkt->psn);
        else if (bth_ack(pkt))
                send_ack(qp, AETH_ACK_UNLIMITED, pkt->psn);

        return RESPST_CLEANUP;
}

static enum resp_states cleanup(struct rxe_qp *qp,
                                struct rxe_pkt_info *pkt)
{
        struct sk_buff *skb;

        if (pkt) {
                skb = skb_dequeue(&qp->req_pkts);
                rxe_put(qp);
                kfree_skb(skb);
                ib_device_put(qp->ibqp.device);
        }

        if (qp->resp.mr) {
                rxe_put(qp->resp.mr);
                qp->resp.mr = NULL;
        }

        return RESPST_DONE;
}

static struct resp_res *find_resource(struct rxe_qp *qp, u32 psn)
{
        int i;

        for (i = 0; i < qp->attr.max_dest_rd_atomic; i++) {
                struct resp_res *res = &qp->resp.resources[i];

                if (res->type == 0)
                        continue;

                if (psn_compare(psn, res->first_psn) >= 0 &&
                    psn_compare(psn, res->last_psn) <= 0) {
                        return res;
                }
        }

        return NULL;
}

static enum resp_states duplicate_request(struct rxe_qp *qp,
                                          struct rxe_pkt_info *pkt)
{
        enum resp_states rc;
        u32 prev_psn = (qp->resp.ack_psn - 1) & BTH_PSN_MASK;

        if (pkt->mask & RXE_SEND_MASK ||
            pkt->mask & RXE_WRITE_MASK) {
                /* SEND. Ack again and cleanup. C9-105. */
                send_ack(qp, AETH_ACK_UNLIMITED, prev_psn);
                return RESPST_CLEANUP;
        } else if (pkt->mask & RXE_FLUSH_MASK) {
                struct resp_res *res;

                /* Find the operation in our list of responder resources. */
                res = find_resource(qp, pkt->psn);
                if (res) {
                        res->replay = 1;
                        res->cur_psn = pkt->psn;
                        qp->resp.res = res;
                        rc = RESPST_PROCESS_FLUSH;
                        goto out;
                }

                /* Resource not found. Class D error. Drop the request. */
                rc = RESPST_CLEANUP;
                goto out;
        } else if (pkt->mask & RXE_READ_MASK) {
                struct resp_res *res;

                res = find_resource(qp, pkt->psn);
                if (!res) {
                        /* Resource not found. Class D error.  Drop the
                         * request.
                         */
                        rc = RESPST_CLEANUP;
                        goto out;
                } else {
                        /* Ensure this new request is the same as the previous
                         * one or a subset of it.
                         */
                        u64 iova = reth_va(pkt);
                        u32 resid = reth_len(pkt);

                        if (iova < res->read.va_org ||
                            resid > res->read.length ||
                            (iova + resid) > (res->read.va_org +
                                              res->read.length)) {
                                rc = RESPST_CLEANUP;
                                goto out;
                        }

                        if (reth_rkey(pkt) != res->read.rkey) {
                                rc = RESPST_CLEANUP;
                                goto out;
                        }

                        res->cur_psn = pkt->psn;
                        res->state = (pkt->psn == res->first_psn) ?
                                        rdatm_res_state_new :
                                        rdatm_res_state_replay;
                        res->replay = 1;

                        /* Reset the resource, except length. */
                        res->read.va_org = iova;
                        res->read.va = iova;
                        res->read.resid = resid;

                        /* Replay the RDMA read reply. */
                        qp->resp.res = res;
                        rc = RESPST_READ_REPLY;
                        goto out;
                }
        } else {
                struct resp_res *res;

                /* Find the operation in our list of responder resources. */
                res = find_resource(qp, pkt->psn);
                if (res) {
                        res->replay = 1;
                        res->cur_psn = pkt->psn;
                        qp->resp.res = res;
                        rc = pkt->mask & RXE_ATOMIC_MASK ?
                                        RESPST_ATOMIC_REPLY :
                                        RESPST_ATOMIC_WRITE_REPLY;
                        goto out;
                }

                /* Resource not found. Class D error. Drop the request. */
                rc = RESPST_CLEANUP;
                goto out;
        }
out:
        return rc;
}

/* Process a class A or C. Both are treated the same in this implementation. */
static void do_class_ac_error(struct rxe_qp *qp, u8 syndrome,
                              enum ib_wc_status status)
{
        qp->resp.aeth_syndrome  = syndrome;
        qp->resp.status         = status;

        /* indicate that we should go through the ERROR state */
        qp->resp.goto_error     = 1;
}

static enum resp_states do_class_d1e_error(struct rxe_qp *qp)
{
        /* UC */
        if (qp->srq) {
                /* Class E */
                qp->resp.drop_msg = 1;
                if (qp->resp.wqe) {
                        qp->resp.status = IB_WC_REM_INV_REQ_ERR;
                        return RESPST_COMPLETE;
                } else {
                        return RESPST_CLEANUP;
                }
        } else {
                /* Class D1. This packet may be the start of a
                 * new message and could be valid. The previous
                 * message is invalid and ignored. reset the
                 * recv wr to its original state
                 */
                if (qp->resp.wqe) {
                        qp->resp.wqe->dma.resid = qp->resp.wqe->dma.length;
                        qp->resp.wqe->dma.cur_sge = 0;
                        qp->resp.wqe->dma.sge_offset = 0;
                        qp->resp.opcode = -1;
                }

                if (qp->resp.mr) {
                        rxe_put(qp->resp.mr);
                        qp->resp.mr = NULL;
                }

                return RESPST_CLEANUP;
        }
}

/* drain incoming request packet queue */
static void drain_req_pkts(struct rxe_qp *qp)
{
        struct sk_buff *skb;

        while ((skb = skb_dequeue(&qp->req_pkts))) {
                rxe_put(qp);
                kfree_skb(skb);
                ib_device_put(qp->ibqp.device);
        }
}

/* complete receive wqe with flush error */
static int flush_recv_wqe(struct rxe_qp *qp, struct rxe_recv_wqe *wqe)
{
        struct rxe_cqe cqe = {};
        struct ib_wc *wc = &cqe.ibwc;
        struct ib_uverbs_wc *uwc = &cqe.uibwc;
        int err;

        if (qp->rcq->is_user) {
                uwc->wr_id = wqe->wr_id;
                uwc->status = IB_WC_WR_FLUSH_ERR;
                uwc->qp_num = qp_num(qp);
        } else {
                wc->wr_id = wqe->wr_id;
                wc->status = IB_WC_WR_FLUSH_ERR;
                wc->qp = &qp->ibqp;
        }

        err = rxe_cq_post(qp->rcq, &cqe, 0);
        if (err)
                rxe_dbg_cq(qp->rcq, "post cq failed err = %d\n", err);

        return err;
}

/* drain and optionally complete the recive queue
 * if unable to complete a wqe stop completing and
 * just flush the remaining wqes
 */
static void flush_recv_queue(struct rxe_qp *qp, bool notify)
{
        struct rxe_queue *q = qp->rq.queue;
        struct rxe_recv_wqe *wqe;
        int err;

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

                        ev.device = qp->ibqp.device;
                        ev.element.qp = &qp->ibqp;
                        ev.event = IB_EVENT_QP_LAST_WQE_REACHED;
                        qp->ibqp.event_handler(&ev, qp->ibqp.qp_context);
                }
                return;
        }

        /* recv queue not created. nothing to do. */
        if (!qp->rq.queue)
                return;

        while ((wqe = queue_head(q, q->type))) {
                if (notify) {
                        err = flush_recv_wqe(qp, wqe);
                        if (err)
                                notify = 0;
                }
                queue_advance_consumer(q, q->type);
        }

        qp->resp.wqe = NULL;
}

int rxe_receiver(struct rxe_qp *qp)
{
        struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
        enum resp_states state;
        struct rxe_pkt_info *pkt = NULL;
        int ret;
        unsigned long flags;

        spin_lock_irqsave(&qp->state_lock, flags);
        if (!qp->valid || qp_state(qp) == IB_QPS_ERR ||
                          qp_state(qp) == IB_QPS_RESET) {
                bool notify = qp->valid && (qp_state(qp) == IB_QPS_ERR);

                drain_req_pkts(qp);
                flush_recv_queue(qp, notify);
                spin_unlock_irqrestore(&qp->state_lock, flags);
                goto exit;
        }
        spin_unlock_irqrestore(&qp->state_lock, flags);

        qp->resp.aeth_syndrome = AETH_ACK_UNLIMITED;

        state = RESPST_GET_REQ;

        while (1) {
                rxe_dbg_qp(qp, "state = %s\n", resp_state_name[state]);
                switch (state) {
                case RESPST_GET_REQ:
                        state = get_req(qp, &pkt);
                        break;
                case RESPST_CHK_PSN:
                        state = check_psn(qp, pkt);
                        break;
                case RESPST_CHK_OP_SEQ:
                        state = check_op_seq(qp, pkt);
                        break;
                case RESPST_CHK_OP_VALID:
                        state = check_op_valid(qp, pkt);
                        break;
                case RESPST_CHK_RESOURCE:
                        state = check_resource(qp, pkt);
                        break;
                case RESPST_CHK_LENGTH:
                        state = rxe_resp_check_length(qp, pkt);
                        break;
                case RESPST_CHK_RKEY:
                        state = check_rkey(qp, pkt);
                        break;
                case RESPST_EXECUTE:
                        state = execute(qp, pkt);
                        break;
                case RESPST_COMPLETE:
                        state = do_complete(qp, pkt);
                        break;
                case RESPST_READ_REPLY:
                        state = read_reply(qp, pkt);
                        break;
                case RESPST_ATOMIC_REPLY:
                        state = atomic_reply(qp, pkt);
                        break;
                case RESPST_ATOMIC_WRITE_REPLY:
                        state = atomic_write_reply(qp, pkt);
                        break;
                case RESPST_PROCESS_FLUSH:
                        state = process_flush(qp, pkt);
                        break;
                case RESPST_ACKNOWLEDGE:
                        state = acknowledge(qp, pkt);
                        break;
                case RESPST_CLEANUP:
                        state = cleanup(qp, pkt);
                        break;
                case RESPST_DUPLICATE_REQUEST:
                        state = duplicate_request(qp, pkt);
                        break;
                case RESPST_ERR_PSN_OUT_OF_SEQ:
                        /* RC only - Class B. Drop packet. */
                        send_ack(qp, AETH_NAK_PSN_SEQ_ERROR, qp->resp.psn);
                        state = RESPST_CLEANUP;
                        break;

                case RESPST_ERR_TOO_MANY_RDMA_ATM_REQ:
                case RESPST_ERR_MISSING_OPCODE_FIRST:
                case RESPST_ERR_MISSING_OPCODE_LAST_C:
                case RESPST_ERR_UNSUPPORTED_OPCODE:
                case RESPST_ERR_MISALIGNED_ATOMIC:
                        /* RC Only - Class C. */
                        do_class_ac_error(qp, AETH_NAK_INVALID_REQ,
                                          IB_WC_REM_INV_REQ_ERR);
                        state = RESPST_COMPLETE;
                        break;

                case RESPST_ERR_MISSING_OPCODE_LAST_D1E:
                        state = do_class_d1e_error(qp);
                        break;
                case RESPST_ERR_RNR:
                        if (qp_type(qp) == IB_QPT_RC) {
                                rxe_counter_inc(rxe, RXE_CNT_SND_RNR);
                                /* RC - class B */
                                send_ack(qp, AETH_RNR_NAK |
                                         (~AETH_TYPE_MASK &
                                         qp->attr.min_rnr_timer),
                                         pkt->psn);
                        } else {
                                /* UD/UC - class D */
                                qp->resp.drop_msg = 1;
                        }
                        state = RESPST_CLEANUP;
                        break;

                case RESPST_ERR_RKEY_VIOLATION:
                        if (qp_type(qp) == IB_QPT_RC) {
                                /* Class C */
                                do_class_ac_error(qp, AETH_NAK_REM_ACC_ERR,
                                                  IB_WC_REM_ACCESS_ERR);
                                state = RESPST_COMPLETE;
                        } else {
                                qp->resp.drop_msg = 1;
                                if (qp->srq) {
                                        /* UC/SRQ Class D */
                                        qp->resp.status = IB_WC_REM_ACCESS_ERR;
                                        state = RESPST_COMPLETE;
                                } else {
                                        /* UC/non-SRQ Class E. */
                                        state = RESPST_CLEANUP;
                                }
                        }
                        break;

                case RESPST_ERR_INVALIDATE_RKEY:
                        /* RC - Class J. */
                        qp->resp.goto_error = 1;
                        qp->resp.status = IB_WC_REM_INV_REQ_ERR;
                        state = RESPST_COMPLETE;
                        break;

                case RESPST_ERR_LENGTH:
                        if (qp_type(qp) == IB_QPT_RC) {
                                /* Class C */
                                do_class_ac_error(qp, AETH_NAK_INVALID_REQ,
                                                  IB_WC_REM_INV_REQ_ERR);
                                state = RESPST_COMPLETE;
                        } else if (qp->srq) {
                                /* UC/UD - class E */
                                qp->resp.status = IB_WC_REM_INV_REQ_ERR;
                                state = RESPST_COMPLETE;
                        } else {
                                /* UC/UD - class D */
                                qp->resp.drop_msg = 1;
                                state = RESPST_CLEANUP;
                        }
                        break;

                case RESPST_ERR_MALFORMED_WQE:
                        /* All, Class A. */
                        do_class_ac_error(qp, AETH_NAK_REM_OP_ERR,
                                          IB_WC_LOC_QP_OP_ERR);
                        state = RESPST_COMPLETE;
                        break;

                case RESPST_ERR_CQ_OVERFLOW:
                        /* All - Class G */
                        state = RESPST_ERROR;
                        break;

                case RESPST_DONE:
                        if (qp->resp.goto_error) {
                                state = RESPST_ERROR;
                                break;
                        }

                        goto done;

                case RESPST_EXIT:
                        if (qp->resp.goto_error) {
                                state = RESPST_ERROR;
                                break;
                        }

                        goto exit;

                case RESPST_ERROR:
                        qp->resp.goto_error = 0;
                        rxe_dbg_qp(qp, "moved to error state\n");
                        rxe_qp_error(qp);
                        goto exit;

                default:
                        WARN_ON_ONCE(1);
                }
        }

        /* A non-zero return value will cause rxe_do_task to
         * exit its loop and end the work item. A zero return
         * will continue looping and return to rxe_responder
         */
done:
        ret = 0;
        goto out;
exit:
        ret = -EAGAIN;
out:
        return ret;
}