ipath_ruc.c

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/*
 * Copyright (c) 2006, 2007, 2008 QLogic Corporation. All rights reserved.
 * Copyright (c) 2005, 2006 PathScale, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/sched.h>
#include <linux/spinlock.h>

#include "ipath_verbs.h"
#include "ipath_kernel.h"

/*
 * Convert the AETH RNR timeout code into the number of milliseconds.
 */
const u32 ib_ipath_rnr_table[32] = {
    656,            /* 0 */
    1,          /* 1 */
    1,          /* 2 */
    1,          /* 3 */
    1,          /* 4 */
    1,          /* 5 */
    1,          /* 6 */
    1,          /* 7 */
    1,          /* 8 */
    1,          /* 9 */
    1,          /* A */
    1,          /* B */
    1,          /* C */
    1,          /* D */
    2,          /* E */
    2,          /* F */
    3,          /* 10 */
    4,          /* 11 */
    6,          /* 12 */
    8,          /* 13 */
    11,         /* 14 */
    16,         /* 15 */
    21,         /* 16 */
    31,         /* 17 */
    41,         /* 18 */
    62,         /* 19 */
    82,         /* 1A */
    123,            /* 1B */
    164,            /* 1C */
    246,            /* 1D */
    328,            /* 1E */
    492         /* 1F */
};

void ipath_insert_rnr_queue(struct ipath_qp *qp)
{
    struct ipath_ibdev *dev = to_idev(qp->ibqp.device);

    /* We already did a spin_lock_irqsave(), so just use spin_lock */
    spin_lock(&dev->pending_lock);
    if (list_empty(&dev->rnrwait))
        list_add(&qp->timerwait, &dev->rnrwait);
    else {
        struct list_head *l = &dev->rnrwait;
        struct ipath_qp *nqp = list_entry(l->next, struct ipath_qp,
                          timerwait);

        while (qp->s_rnr_timeout >= nqp->s_rnr_timeout) {
            qp->s_rnr_timeout -= nqp->s_rnr_timeout;
            l = l->next;
            if (l->next == &dev->rnrwait) {
                nqp = NULL;
                break;
            }
            nqp = list_entry(l->next, struct ipath_qp,
                     timerwait);
        }
        if (nqp)
            nqp->s_rnr_timeout -= qp->s_rnr_timeout;
        list_add(&qp->timerwait, l);
    }
    spin_unlock(&dev->pending_lock);
}

int ipath_init_sge(struct ipath_qp *qp, struct ipath_rwqe *wqe,
           u32 *lengthp, struct ipath_sge_state *ss)
{
    int i, j, ret;
    struct ib_wc wc;

    *lengthp = 0;
    for (i = j = 0; i < wqe->num_sge; i++) {
        if (wqe->sg_list[i].length == 0)
            continue;
        /* Check LKEY */
        if (!ipath_lkey_ok(qp, j ? &ss->sg_list[j - 1] : &ss->sge,
                   &wqe->sg_list[i], IB_ACCESS_LOCAL_WRITE))
            goto bad_lkey;
        *lengthp += wqe->sg_list[i].length;
        j++;
    }
    ss->num_sge = j;
    ret = 1;
    goto bail;

bad_lkey:
    memset(&wc, 0, sizeof(wc));
    wc.wr_id = wqe->wr_id;
    wc.status = IB_WC_LOC_PROT_ERR;
    wc.opcode = IB_WC_RECV;
    wc.qp = &qp->ibqp;
    /* Signal solicited completion event. */
    ipath_cq_enter(to_icq(qp->ibqp.recv_cq), &wc, 1);
    ret = 0;
bail:
    return ret;
}

int ipath_get_rwqe(struct ipath_qp *qp, int wr_id_only)
{
    unsigned long flags;
    struct ipath_rq *rq;
    struct ipath_rwq *wq;
    struct ipath_srq *srq;
    struct ipath_rwqe *wqe;
    void (*handler)(struct ib_event *, void *);
    u32 tail;
    int ret;

    if (qp->ibqp.srq) {
        srq = to_isrq(qp->ibqp.srq);
        handler = srq->ibsrq.event_handler;
        rq = &srq->rq;
    } else {
        srq = NULL;
        handler = NULL;
        rq = &qp->r_rq;
    }

    spin_lock_irqsave(&rq->lock, flags);
    if (!(ib_ipath_state_ops[qp->state] & IPATH_PROCESS_RECV_OK)) {
        ret = 0;
        goto unlock;
    }

    wq = rq->wq;
    tail = wq->tail;
    /* Validate tail before using it since it is user writable. */
    if (tail >= rq->size)
        tail = 0;
    do {
        if (unlikely(tail == wq->head)) {
            ret = 0;
            goto unlock;
        }
        /* Make sure entry is read after head index is read. */
        smp_rmb();
        wqe = get_rwqe_ptr(rq, tail);
        if (++tail >= rq->size)
            tail = 0;
        if (wr_id_only)
            break;
        qp->r_sge.sg_list = qp->r_sg_list;
    } while (!ipath_init_sge(qp, wqe, &qp->r_len, &qp->r_sge));
    qp->r_wr_id = wqe->wr_id;
    wq->tail = tail;

    ret = 1;
    set_bit(IPATH_R_WRID_VALID, &qp->r_aflags);
    if (handler) {
        u32 n;

        /*
         * validate head pointer value and compute
         * the number of remaining WQEs.
         */
        n = wq->head;
        if (n >= rq->size)
            n = 0;
        if (n < tail)
            n += rq->size - tail;
        else
            n -= tail;
        if (n < srq->limit) {
            struct ib_event ev;

            srq->limit = 0;
            spin_unlock_irqrestore(&rq->lock, flags);
            ev.device = qp->ibqp.device;
            ev.element.srq = qp->ibqp.srq;
            ev.event = IB_EVENT_SRQ_LIMIT_REACHED;
            handler(&ev, srq->ibsrq.srq_context);
            goto bail;
        }
    }
unlock:
    spin_unlock_irqrestore(&rq->lock, flags);
bail:
    return ret;
}

static void ipath_ruc_loopback(struct ipath_qp *sqp)
{
    struct ipath_ibdev *dev = to_idev(sqp->ibqp.device);
    struct ipath_qp *qp;
    struct ipath_swqe *wqe;
    struct ipath_sge *sge;
    unsigned long flags;
    struct ib_wc wc;
    u64 sdata;
    atomic64_t *maddr;
    enum ib_wc_status send_status;

    /*
     * Note that we check the responder QP state after
     * checking the requester's state.
     */
    qp = ipath_lookup_qpn(&dev->qp_table, sqp->remote_qpn);

    spin_lock_irqsave(&sqp->s_lock, flags);

    /* Return if we are already busy processing a work request. */
    if ((sqp->s_flags & (IPATH_S_BUSY | IPATH_S_ANY_WAIT)) ||
        !(ib_ipath_state_ops[sqp->state] & IPATH_PROCESS_OR_FLUSH_SEND))
        goto unlock;

    sqp->s_flags |= IPATH_S_BUSY;

again:
    if (sqp->s_last == sqp->s_head)
        goto clr_busy;
    wqe = get_swqe_ptr(sqp, sqp->s_last);

    /* Return if it is not OK to start a new work reqeust. */
    if (!(ib_ipath_state_ops[sqp->state] & IPATH_PROCESS_NEXT_SEND_OK)) {
        if (!(ib_ipath_state_ops[sqp->state] & IPATH_FLUSH_SEND))
            goto clr_busy;
        /* We are in the error state, flush the work request. */
        send_status = IB_WC_WR_FLUSH_ERR;
        goto flush_send;
    }

    /*
     * We can rely on the entry not changing without the s_lock
     * being held until we update s_last.
     * We increment s_cur to indicate s_last is in progress.
     */
    if (sqp->s_last == sqp->s_cur) {
        if (++sqp->s_cur >= sqp->s_size)
            sqp->s_cur = 0;
    }
    spin_unlock_irqrestore(&sqp->s_lock, flags);

    if (!qp || !(ib_ipath_state_ops[qp->state] & IPATH_PROCESS_RECV_OK)) {
        dev->n_pkt_drops++;
        /*
         * For RC, the requester would timeout and retry so
         * shortcut the timeouts and just signal too many retries.
         */
        if (sqp->ibqp.qp_type == IB_QPT_RC)
            send_status = IB_WC_RETRY_EXC_ERR;
        else
            send_status = IB_WC_SUCCESS;
        goto serr;
    }

    memset(&wc, 0, sizeof wc);
    send_status = IB_WC_SUCCESS;

    sqp->s_sge.sge = wqe->sg_list[0];
    sqp->s_sge.sg_list = wqe->sg_list + 1;
    sqp->s_sge.num_sge = wqe->wr.num_sge;
    sqp->s_len = wqe->length;
    switch (wqe->wr.opcode) {
    case IB_WR_SEND_WITH_IMM:
        wc.wc_flags = IB_WC_WITH_IMM;
        wc.ex.imm_data = wqe->wr.ex.imm_data;
        /* FALLTHROUGH */
    case IB_WR_SEND:
        if (!ipath_get_rwqe(qp, 0))
            goto rnr_nak;
        break;

    case IB_WR_RDMA_WRITE_WITH_IMM:
        if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_WRITE)))
            goto inv_err;
        wc.wc_flags = IB_WC_WITH_IMM;
        wc.ex.imm_data = wqe->wr.ex.imm_data;
        if (!ipath_get_rwqe(qp, 1))
            goto rnr_nak;
        /* FALLTHROUGH */
    case IB_WR_RDMA_WRITE:
        if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_WRITE)))
            goto inv_err;
        if (wqe->length == 0)
            break;
        if (unlikely(!ipath_rkey_ok(qp, &qp->r_sge, wqe->length,
                        wqe->wr.wr.rdma.remote_addr,
                        wqe->wr.wr.rdma.rkey,
                        IB_ACCESS_REMOTE_WRITE)))
            goto acc_err;
        break;

    case IB_WR_RDMA_READ:
        if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_READ)))
            goto inv_err;
        if (unlikely(!ipath_rkey_ok(qp, &sqp->s_sge, wqe->length,
                        wqe->wr.wr.rdma.remote_addr,
                        wqe->wr.wr.rdma.rkey,
                        IB_ACCESS_REMOTE_READ)))
            goto acc_err;
        qp->r_sge.sge = wqe->sg_list[0];
        qp->r_sge.sg_list = wqe->sg_list + 1;
        qp->r_sge.num_sge = wqe->wr.num_sge;
        break;

    case IB_WR_ATOMIC_CMP_AND_SWP:
    case IB_WR_ATOMIC_FETCH_AND_ADD:
        if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_ATOMIC)))
            goto inv_err;
        if (unlikely(!ipath_rkey_ok(qp, &qp->r_sge, sizeof(u64),
                        wqe->wr.wr.atomic.remote_addr,
                        wqe->wr.wr.atomic.rkey,
                        IB_ACCESS_REMOTE_ATOMIC)))
            goto acc_err;
        /* Perform atomic OP and save result. */
        maddr = (atomic64_t *) qp->r_sge.sge.vaddr;
        sdata = wqe->wr.wr.atomic.compare_add;
        *(u64 *) sqp->s_sge.sge.vaddr =
            (wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD) ?
            (u64) atomic64_add_return(sdata, maddr) - sdata :
            (u64) cmpxchg((u64 *) qp->r_sge.sge.vaddr,
                      sdata, wqe->wr.wr.atomic.swap);
        goto send_comp;

    default:
        send_status = IB_WC_LOC_QP_OP_ERR;
        goto serr;
    }

    sge = &sqp->s_sge.sge;
    while (sqp->s_len) {
        u32 len = sqp->s_len;

        if (len > sge->length)
            len = sge->length;
        if (len > sge->sge_length)
            len = sge->sge_length;
        BUG_ON(len == 0);
        ipath_copy_sge(&qp->r_sge, sge->vaddr, len);
        sge->vaddr += len;
        sge->length -= len;
        sge->sge_length -= len;
        if (sge->sge_length == 0) {
            if (--sqp->s_sge.num_sge)
                *sge = *sqp->s_sge.sg_list++;
        } else if (sge->length == 0 && sge->mr != NULL) {
            if (++sge->n >= IPATH_SEGSZ) {
                if (++sge->m >= sge->mr->mapsz)
                    break;
                sge->n = 0;
            }
            sge->vaddr =
                sge->mr->map[sge->m]->segs[sge->n].vaddr;
            sge->length =
                sge->mr->map[sge->m]->segs[sge->n].length;
        }
        sqp->s_len -= len;
    }

    if (!test_and_clear_bit(IPATH_R_WRID_VALID, &qp->r_aflags))
        goto send_comp;

    if (wqe->wr.opcode == IB_WR_RDMA_WRITE_WITH_IMM)
        wc.opcode = IB_WC_RECV_RDMA_WITH_IMM;
    else
        wc.opcode = IB_WC_RECV;
    wc.wr_id = qp->r_wr_id;
    wc.status = IB_WC_SUCCESS;
    wc.byte_len = wqe->length;
    wc.qp = &qp->ibqp;
    wc.src_qp = qp->remote_qpn;
    wc.slid = qp->remote_ah_attr.dlid;
    wc.sl = qp->remote_ah_attr.sl;
    wc.port_num = 1;
    /* Signal completion event if the solicited bit is set. */
    ipath_cq_enter(to_icq(qp->ibqp.recv_cq), &wc,
               wqe->wr.send_flags & IB_SEND_SOLICITED);

send_comp:
    spin_lock_irqsave(&sqp->s_lock, flags);
flush_send:
    sqp->s_rnr_retry = sqp->s_rnr_retry_cnt;
    ipath_send_complete(sqp, wqe, send_status);
    goto again;

rnr_nak:
    /* Handle RNR NAK */
    if (qp->ibqp.qp_type == IB_QPT_UC)
        goto send_comp;
    /*
     * Note: we don't need the s_lock held since the BUSY flag
     * makes this single threaded.
     */
    if (sqp->s_rnr_retry == 0) {
        send_status = IB_WC_RNR_RETRY_EXC_ERR;
        goto serr;
    }
    if (sqp->s_rnr_retry_cnt < 7)
        sqp->s_rnr_retry--;
    spin_lock_irqsave(&sqp->s_lock, flags);
    if (!(ib_ipath_state_ops[sqp->state] & IPATH_PROCESS_RECV_OK))
        goto clr_busy;
    sqp->s_flags |= IPATH_S_WAITING;
    dev->n_rnr_naks++;
    sqp->s_rnr_timeout = ib_ipath_rnr_table[qp->r_min_rnr_timer];
    ipath_insert_rnr_queue(sqp);
    goto clr_busy;

inv_err:
    send_status = IB_WC_REM_INV_REQ_ERR;
    wc.status = IB_WC_LOC_QP_OP_ERR;
    goto err;

acc_err:
    send_status = IB_WC_REM_ACCESS_ERR;
    wc.status = IB_WC_LOC_PROT_ERR;
err:
    /* responder goes to error state */
    ipath_rc_error(qp, wc.status);

serr:
    spin_lock_irqsave(&sqp->s_lock, flags);
    ipath_send_complete(sqp, wqe, send_status);
    if (sqp->ibqp.qp_type == IB_QPT_RC) {
        int lastwqe = ipath_error_qp(sqp, IB_WC_WR_FLUSH_ERR);

        sqp->s_flags &= ~IPATH_S_BUSY;
        spin_unlock_irqrestore(&sqp->s_lock, flags);
        if (lastwqe) {
            struct ib_event ev;

            ev.device = sqp->ibqp.device;
            ev.element.qp = &sqp->ibqp;
            ev.event = IB_EVENT_QP_LAST_WQE_REACHED;
            sqp->ibqp.event_handler(&ev, sqp->ibqp.qp_context);
        }
        goto done;
    }
clr_busy:
    sqp->s_flags &= ~IPATH_S_BUSY;
unlock:
    spin_unlock_irqrestore(&sqp->s_lock, flags);
done:
    if (qp && atomic_dec_and_test(&qp->refcount))
        wake_up(&qp->wait);
}

static void want_buffer(struct ipath_devdata *dd, struct ipath_qp *qp)
{
    if (!(dd->ipath_flags & IPATH_HAS_SEND_DMA) ||
        qp->ibqp.qp_type == IB_QPT_SMI) {
        unsigned long flags;

        spin_lock_irqsave(&dd->ipath_sendctrl_lock, flags);
        dd->ipath_sendctrl |= INFINIPATH_S_PIOINTBUFAVAIL;
        ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl,
                 dd->ipath_sendctrl);
        ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
        spin_unlock_irqrestore(&dd->ipath_sendctrl_lock, flags);
    }
}

static int ipath_no_bufs_available(struct ipath_qp *qp,
                    struct ipath_ibdev *dev)
{
    unsigned long flags;
    int ret = 1;

    /*
     * Note that as soon as want_buffer() is called and
     * possibly before it returns, ipath_ib_piobufavail()
     * could be called. Therefore, put QP on the piowait list before
     * enabling the PIO avail interrupt.
     */
    spin_lock_irqsave(&qp->s_lock, flags);
    if (ib_ipath_state_ops[qp->state] & IPATH_PROCESS_SEND_OK) {
        dev->n_piowait++;
        qp->s_flags |= IPATH_S_WAITING;
        qp->s_flags &= ~IPATH_S_BUSY;
        spin_lock(&dev->pending_lock);
        if (list_empty(&qp->piowait))
            list_add_tail(&qp->piowait, &dev->piowait);
        spin_unlock(&dev->pending_lock);
    } else
        ret = 0;
    spin_unlock_irqrestore(&qp->s_lock, flags);
    if (ret)
        want_buffer(dev->dd, qp);
    return ret;
}

u32 ipath_make_grh(struct ipath_ibdev *dev, struct ib_grh *hdr,
           struct ib_global_route *grh, u32 hwords, u32 nwords)
{
    hdr->version_tclass_flow =
        cpu_to_be32((6 << 28) |
                (grh->traffic_class << 20) |
                grh->flow_label);
    hdr->paylen = cpu_to_be16((hwords - 2 + nwords + SIZE_OF_CRC) << 2);
    /* next_hdr is defined by C8-7 in ch. 8.4.1 */
    hdr->next_hdr = 0x1B;
    hdr->hop_limit = grh->hop_limit;
    /* The SGID is 32-bit aligned. */
    hdr->sgid.global.subnet_prefix = dev->gid_prefix;
    hdr->sgid.global.interface_id = dev->dd->ipath_guid;
    hdr->dgid = grh->dgid;

    /* GRH header size in 32-bit words. */
    return sizeof(struct ib_grh) / sizeof(u32);
}

void ipath_make_ruc_header(struct ipath_ibdev *dev, struct ipath_qp *qp,
               struct ipath_other_headers *ohdr,
               u32 bth0, u32 bth2)
{
    u16 lrh0;
    u32 nwords;
    u32 extra_bytes;

    /* Construct the header. */
    extra_bytes = -qp->s_cur_size & 3;
    nwords = (qp->s_cur_size + extra_bytes) >> 2;
    lrh0 = IPATH_LRH_BTH;
    if (unlikely(qp->remote_ah_attr.ah_flags & IB_AH_GRH)) {
        qp->s_hdrwords += ipath_make_grh(dev, &qp->s_hdr.u.l.grh,
                         &qp->remote_ah_attr.grh,
                         qp->s_hdrwords, nwords);
        lrh0 = IPATH_LRH_GRH;
    }
    lrh0 |= qp->remote_ah_attr.sl << 4;
    qp->s_hdr.lrh[0] = cpu_to_be16(lrh0);
    qp->s_hdr.lrh[1] = cpu_to_be16(qp->remote_ah_attr.dlid);
    qp->s_hdr.lrh[2] = cpu_to_be16(qp->s_hdrwords + nwords + SIZE_OF_CRC);
    qp->s_hdr.lrh[3] = cpu_to_be16(dev->dd->ipath_lid |
                       qp->remote_ah_attr.src_path_bits);
    bth0 |= ipath_get_pkey(dev->dd, qp->s_pkey_index);
    bth0 |= extra_bytes << 20;
    ohdr->bth[0] = cpu_to_be32(bth0 | (1 << 22));
    ohdr->bth[1] = cpu_to_be32(qp->remote_qpn);
    ohdr->bth[2] = cpu_to_be32(bth2);
}

void ipath_do_send(unsigned long data)
{
    struct ipath_qp *qp = (struct ipath_qp *)data;
    struct ipath_ibdev *dev = to_idev(qp->ibqp.device);
    int (*make_req)(struct ipath_qp *qp);
    unsigned long flags;

    if ((qp->ibqp.qp_type == IB_QPT_RC ||
         qp->ibqp.qp_type == IB_QPT_UC) &&
        qp->remote_ah_attr.dlid == dev->dd->ipath_lid) {
        ipath_ruc_loopback(qp);
        goto bail;
    }

    if (qp->ibqp.qp_type == IB_QPT_RC)
           make_req = ipath_make_rc_req;
    else if (qp->ibqp.qp_type == IB_QPT_UC)
           make_req = ipath_make_uc_req;
    else
           make_req = ipath_make_ud_req;

    spin_lock_irqsave(&qp->s_lock, flags);

    /* Return if we are already busy processing a work request. */
    if ((qp->s_flags & (IPATH_S_BUSY | IPATH_S_ANY_WAIT)) ||
        !(ib_ipath_state_ops[qp->state] & IPATH_PROCESS_OR_FLUSH_SEND)) {
        spin_unlock_irqrestore(&qp->s_lock, flags);
        goto bail;
    }

    qp->s_flags |= IPATH_S_BUSY;

    spin_unlock_irqrestore(&qp->s_lock, flags);

again:
    /* Check for a constructed packet to be sent. */
    if (qp->s_hdrwords != 0) {
        /*
         * If no PIO bufs are available, return.  An interrupt will
         * call ipath_ib_piobufavail() when one is available.
         */
        if (ipath_verbs_send(qp, &qp->s_hdr, qp->s_hdrwords,
                     qp->s_cur_sge, qp->s_cur_size)) {
            if (ipath_no_bufs_available(qp, dev))
                goto bail;
        }
        dev->n_unicast_xmit++;
        /* Record that we sent the packet and s_hdr is empty. */
        qp->s_hdrwords = 0;
    }

    if (make_req(qp))
        goto again;

bail:;
}

/*
 * This should be called with s_lock held.
 */
void ipath_send_complete(struct ipath_qp *qp, struct ipath_swqe *wqe,
             enum ib_wc_status status)
{
    u32 old_last, last;

    if (!(ib_ipath_state_ops[qp->state] & IPATH_PROCESS_OR_FLUSH_SEND))
        return;

    /* See ch. 11.2.4.1 and 10.7.3.1 */
    if (!(qp->s_flags & IPATH_S_SIGNAL_REQ_WR) ||
        (wqe->wr.send_flags & IB_SEND_SIGNALED) ||
        status != IB_WC_SUCCESS) {
        struct ib_wc wc;

        memset(&wc, 0, sizeof wc);
        wc.wr_id = wqe->wr.wr_id;
        wc.status = status;
        wc.opcode = ib_ipath_wc_opcode[wqe->wr.opcode];
        wc.qp = &qp->ibqp;
        if (status == IB_WC_SUCCESS)
            wc.byte_len = wqe->length;
        ipath_cq_enter(to_icq(qp->ibqp.send_cq), &wc,
                   status != IB_WC_SUCCESS);
    }

    old_last = last = qp->s_last;
    if (++last >= qp->s_size)
        last = 0;
    qp->s_last = last;
    if (qp->s_cur == old_last)
        qp->s_cur = last;
    if (qp->s_tail == old_last)
        qp->s_tail = last;
    if (qp->state == IB_QPS_SQD && last == qp->s_cur)
        qp->s_draining = 0;
}