/*
 * 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/spinlock.h>

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

static int gid_ok(union ib_gid *gid, __be64 gid_prefix, __be64 id)
{
        return (gid->global.interface_id == id &&
                (gid->global.subnet_prefix == gid_prefix ||
                 gid->global.subnet_prefix == IB_DEFAULT_GID_PREFIX));
}

/*
 *
 * This should be called with the QP r_lock held.
 *
 * The s_lock will be acquired around the hfi1_migrate_qp() call.
 */
int hfi1_ruc_check_hdr(struct hfi1_ibport *ibp, struct hfi1_packet *packet)
{
        __be64 guid;
        unsigned long flags;
        struct rvt_qp *qp = packet->qp;
        u8 sc5 = ibp->sl_to_sc[rdma_ah_get_sl(&qp->remote_ah_attr)];
        u32 dlid = packet->dlid;
        u32 slid = packet->slid;
        u32 sl = packet->sl;
        bool migrated = packet->migrated;
        u16 pkey = packet->pkey;

        if (qp->s_mig_state == IB_MIG_ARMED && migrated) {
                if (!packet->grh) {
                        if ((rdma_ah_get_ah_flags(&qp->alt_ah_attr) &
                             IB_AH_GRH) &&
                            (packet->etype != RHF_RCV_TYPE_BYPASS))
                                return 1;
                } else {
                        const struct ib_global_route *grh;

                        if (!(rdma_ah_get_ah_flags(&qp->alt_ah_attr) &
                              IB_AH_GRH))
                                return 1;
                        grh = rdma_ah_read_grh(&qp->alt_ah_attr);
                        guid = get_sguid(ibp, grh->sgid_index);
                        if (!gid_ok(&packet->grh->dgid, ibp->rvp.gid_prefix,
                                    guid))
                                return 1;
                        if (!gid_ok(
                                &packet->grh->sgid,
                                grh->dgid.global.subnet_prefix,
                                grh->dgid.global.interface_id))
                                return 1;
                }
                if (unlikely(rcv_pkey_check(ppd_from_ibp(ibp), pkey,
                                            sc5, slid))) {
                        hfi1_bad_pkey(ibp, pkey, sl, 0, qp->ibqp.qp_num,
                                      slid, dlid);
                        return 1;
                }
                /* Validate the SLID. See Ch. 9.6.1.5 and 17.2.8 */
                if (slid != rdma_ah_get_dlid(&qp->alt_ah_attr) ||
                    ppd_from_ibp(ibp)->port !=
                        rdma_ah_get_port_num(&qp->alt_ah_attr))
                        return 1;
                spin_lock_irqsave(&qp->s_lock, flags);
                hfi1_migrate_qp(qp);
                spin_unlock_irqrestore(&qp->s_lock, flags);
        } else {
                if (!packet->grh) {
                        if ((rdma_ah_get_ah_flags(&qp->remote_ah_attr) &
                             IB_AH_GRH) &&
                            (packet->etype != RHF_RCV_TYPE_BYPASS))
                                return 1;
                } else {
                        const struct ib_global_route *grh;

                        if (!(rdma_ah_get_ah_flags(&qp->remote_ah_attr) &
                                                   IB_AH_GRH))
                                return 1;
                        grh = rdma_ah_read_grh(&qp->remote_ah_attr);
                        guid = get_sguid(ibp, grh->sgid_index);
                        if (!gid_ok(&packet->grh->dgid, ibp->rvp.gid_prefix,
                                    guid))
                                return 1;
                        if (!gid_ok(
                             &packet->grh->sgid,
                             grh->dgid.global.subnet_prefix,
                             grh->dgid.global.interface_id))
                                return 1;
                }
                if (unlikely(rcv_pkey_check(ppd_from_ibp(ibp), pkey,
                                            sc5, slid))) {
                        hfi1_bad_pkey(ibp, pkey, sl, 0, qp->ibqp.qp_num,
                                      slid, dlid);
                        return 1;
                }
                /* Validate the SLID. See Ch. 9.6.1.5 */
                if ((slid != rdma_ah_get_dlid(&qp->remote_ah_attr)) ||
                    ppd_from_ibp(ibp)->port != qp->port_num)
                        return 1;
                if (qp->s_mig_state == IB_MIG_REARM && !migrated)
                        qp->s_mig_state = IB_MIG_ARMED;
        }

        return 0;
}

/**
 * hfi1_make_grh - construct a GRH header
 * @ibp: a pointer to the IB port
 * @hdr: a pointer to the GRH header being constructed
 * @grh: the global route address to send to
 * @hwords: size of header after grh being sent in dwords
 * @nwords: the number of 32 bit words of data being sent
 *
 * Return the size of the header in 32 bit words.
 */
u32 hfi1_make_grh(struct hfi1_ibport *ibp, struct ib_grh *hdr,
                  const struct ib_global_route *grh, u32 hwords, u32 nwords)
{
        hdr->version_tclass_flow =
                cpu_to_be32((IB_GRH_VERSION << IB_GRH_VERSION_SHIFT) |
                            (grh->traffic_class << IB_GRH_TCLASS_SHIFT) |
                            (grh->flow_label << IB_GRH_FLOW_SHIFT));
        hdr->paylen = cpu_to_be16((hwords + nwords) << 2);
        /* next_hdr is defined by C8-7 in ch. 8.4.1 */
        hdr->next_hdr = IB_GRH_NEXT_HDR;
        hdr->hop_limit = grh->hop_limit;
        /* The SGID is 32-bit aligned. */
        hdr->sgid.global.subnet_prefix = ibp->rvp.gid_prefix;
        hdr->sgid.global.interface_id =
                grh->sgid_index < HFI1_GUIDS_PER_PORT ?
                get_sguid(ibp, grh->sgid_index) :
                get_sguid(ibp, HFI1_PORT_GUID_INDEX);
        hdr->dgid = grh->dgid;

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

#define BTH2_OFFSET (offsetof(struct hfi1_sdma_header, \
                              hdr.ibh.u.oth.bth[2]) / 4)

/**
 * build_ahg - create ahg in s_ahg
 * @qp: a pointer to QP
 * @npsn: the next PSN for the request/response
 *
 * This routine handles the AHG by allocating an ahg entry and causing the
 * copy of the first middle.
 *
 * Subsequent middles use the copied entry, editing the
 * PSN with 1 or 2 edits.
 */
static inline void build_ahg(struct rvt_qp *qp, u32 npsn)
{
        struct hfi1_qp_priv *priv = qp->priv;

        if (unlikely(qp->s_flags & HFI1_S_AHG_CLEAR))
                clear_ahg(qp);
        if (!(qp->s_flags & HFI1_S_AHG_VALID)) {
                /* first middle that needs copy  */
                if (qp->s_ahgidx < 0)
                        qp->s_ahgidx = sdma_ahg_alloc(priv->s_sde);
                if (qp->s_ahgidx >= 0) {
                        qp->s_ahgpsn = npsn;
                        priv->s_ahg->tx_flags |= SDMA_TXREQ_F_AHG_COPY;
                        /* save to protect a change in another thread */
                        priv->s_ahg->ahgidx = qp->s_ahgidx;
                        qp->s_flags |= HFI1_S_AHG_VALID;
                }
        } else {
                /* subsequent middle after valid */
                if (qp->s_ahgidx >= 0) {
                        priv->s_ahg->tx_flags |= SDMA_TXREQ_F_USE_AHG;
                        priv->s_ahg->ahgidx = qp->s_ahgidx;
                        priv->s_ahg->ahgcount++;
                        priv->s_ahg->ahgdesc[0] =
                                sdma_build_ahg_descriptor(
                                        (__force u16)cpu_to_be16((u16)npsn),
                                        BTH2_OFFSET,
                                        16,
                                        16);
                        if ((npsn & 0xffff0000) !=
                                        (qp->s_ahgpsn & 0xffff0000)) {
                                priv->s_ahg->ahgcount++;
                                priv->s_ahg->ahgdesc[1] =
                                        sdma_build_ahg_descriptor(
                                                (__force u16)cpu_to_be16(
                                                        (u16)(npsn >> 16)),
                                                BTH2_OFFSET,
                                                0,
                                                16);
                        }
                }
        }
}

static inline void hfi1_make_ruc_bth(struct rvt_qp *qp,
                                     struct ib_other_headers *ohdr,
                                     u32 bth0, u32 bth1, u32 bth2)
{
        ohdr->bth[0] = cpu_to_be32(bth0);
        ohdr->bth[1] = cpu_to_be32(bth1);
        ohdr->bth[2] = cpu_to_be32(bth2);
}

/**
 * hfi1_make_ruc_header_16B - build a 16B header
 * @qp: the queue pair
 * @ohdr: a pointer to the destination header memory
 * @bth0: bth0 passed in from the RC/UC builder
 * @bth2: bth2 passed in from the RC/UC builder
 * @middle: non zero implies indicates ahg "could" be used
 * @ps: the current packet state
 *
 * This routine may disarm ahg under these situations:
 * - packet needs a GRH
 * - BECN needed
 * - migration state not IB_MIG_MIGRATED
 */
static inline void hfi1_make_ruc_header_16B(struct rvt_qp *qp,
                                            struct ib_other_headers *ohdr,
                                            u32 bth0, u32 bth1, u32 bth2,
                                            int middle,
                                            struct hfi1_pkt_state *ps)
{
        struct hfi1_qp_priv *priv = qp->priv;
        struct hfi1_ibport *ibp = ps->ibp;
        struct hfi1_pportdata *ppd = ppd_from_ibp(ibp);
        u32 slid;
        u16 pkey = hfi1_get_pkey(ibp, qp->s_pkey_index);
        u8 l4 = OPA_16B_L4_IB_LOCAL;
        u8 extra_bytes = hfi1_get_16b_padding(
                                (ps->s_txreq->hdr_dwords << 2),
                                ps->s_txreq->s_cur_size);
        u32 nwords = SIZE_OF_CRC + ((ps->s_txreq->s_cur_size +
                                 extra_bytes + SIZE_OF_LT) >> 2);
        bool becn = false;

        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))) {
                struct ib_grh *grh;
                struct ib_global_route *grd =
                        rdma_ah_retrieve_grh(&qp->remote_ah_attr);
                /*
                 * Ensure OPA GIDs are transformed to IB gids
                 * before creating the GRH.
                 */
                if (grd->sgid_index == OPA_GID_INDEX)
                        grd->sgid_index = 0;
                grh = &ps->s_txreq->phdr.hdr.opah.u.l.grh;
                l4 = OPA_16B_L4_IB_GLOBAL;
                ps->s_txreq->hdr_dwords +=
                        hfi1_make_grh(ibp, grh, grd,
                                      ps->s_txreq->hdr_dwords - LRH_16B_DWORDS,
                                      nwords);
                middle = 0;
        }

        if (qp->s_mig_state == IB_MIG_MIGRATED)
                bth1 |= OPA_BTH_MIG_REQ;
        else
                middle = 0;

        if (qp->s_flags & RVT_S_ECN) {
                qp->s_flags &= ~RVT_S_ECN;
                /* we recently received a FECN, so return a BECN */
                becn = true;
                middle = 0;
        }
        if (middle)
                build_ahg(qp, bth2);
        else
                qp->s_flags &= ~HFI1_S_AHG_VALID;

        bth0 |= pkey;
        bth0 |= extra_bytes << 20;
        hfi1_make_ruc_bth(qp, ohdr, bth0, bth1, bth2);

        if (!ppd->lid)
                slid = be32_to_cpu(OPA_LID_PERMISSIVE);
        else
                slid = ppd->lid |
                        (rdma_ah_get_path_bits(&qp->remote_ah_attr) &
                        ((1 << ppd->lmc) - 1));

        hfi1_make_16b_hdr(&ps->s_txreq->phdr.hdr.opah,
                          slid,
                          opa_get_lid(rdma_ah_get_dlid(&qp->remote_ah_attr),
                                      16B),
                          (ps->s_txreq->hdr_dwords + nwords) >> 1,
                          pkey, becn, 0, l4, priv->s_sc);
}

/**
 * hfi1_make_ruc_header_9B - build a 9B header
 * @qp: the queue pair
 * @ohdr: a pointer to the destination header memory
 * @bth0: bth0 passed in from the RC/UC builder
 * @bth2: bth2 passed in from the RC/UC builder
 * @middle: non zero implies indicates ahg "could" be used
 * @ps: the current packet state
 *
 * This routine may disarm ahg under these situations:
 * - packet needs a GRH
 * - BECN needed
 * - migration state not IB_MIG_MIGRATED
 */
static inline void hfi1_make_ruc_header_9B(struct rvt_qp *qp,
                                           struct ib_other_headers *ohdr,
                                           u32 bth0, u32 bth1, u32 bth2,
                                           int middle,
                                           struct hfi1_pkt_state *ps)
{
        struct hfi1_qp_priv *priv = qp->priv;
        struct hfi1_ibport *ibp = ps->ibp;
        u16 pkey = hfi1_get_pkey(ibp, qp->s_pkey_index);
        u16 lrh0 = HFI1_LRH_BTH;
        u8 extra_bytes = -ps->s_txreq->s_cur_size & 3;
        u32 nwords = SIZE_OF_CRC + ((ps->s_txreq->s_cur_size +
                                         extra_bytes) >> 2);

        if (unlikely(rdma_ah_get_ah_flags(&qp->remote_ah_attr) & IB_AH_GRH)) {
                struct ib_grh *grh = &ps->s_txreq->phdr.hdr.ibh.u.l.grh;

                lrh0 = HFI1_LRH_GRH;
                ps->s_txreq->hdr_dwords +=
                        hfi1_make_grh(ibp, grh,
                                      rdma_ah_read_grh(&qp->remote_ah_attr),
                                      ps->s_txreq->hdr_dwords - LRH_9B_DWORDS,
                                      nwords);
                middle = 0;
        }
        lrh0 |= (priv->s_sc & 0xf) << 12 |
                (rdma_ah_get_sl(&qp->remote_ah_attr) & 0xf) << 4;

        if (qp->s_mig_state == IB_MIG_MIGRATED)
                bth0 |= IB_BTH_MIG_REQ;
        else
                middle = 0;

        if (qp->s_flags & RVT_S_ECN) {
                qp->s_flags &= ~RVT_S_ECN;
                /* we recently received a FECN, so return a BECN */
                bth1 |= (IB_BECN_MASK << IB_BECN_SHIFT);
                middle = 0;
        }
        if (middle)
                build_ahg(qp, bth2);
        else
                qp->s_flags &= ~HFI1_S_AHG_VALID;

        bth0 |= pkey;
        bth0 |= extra_bytes << 20;
        hfi1_make_ruc_bth(qp, ohdr, bth0, bth1, bth2);
        hfi1_make_ib_hdr(&ps->s_txreq->phdr.hdr.ibh,
                         lrh0,
                         ps->s_txreq->hdr_dwords + nwords,
                         opa_get_lid(rdma_ah_get_dlid(&qp->remote_ah_attr), 9B),
                         ppd_from_ibp(ibp)->lid |
                                rdma_ah_get_path_bits(&qp->remote_ah_attr));
}

typedef void (*hfi1_make_ruc_hdr)(struct rvt_qp *qp,
                                  struct ib_other_headers *ohdr,
                                  u32 bth0, u32 bth1, u32 bth2, int middle,
                                  struct hfi1_pkt_state *ps);

/* We support only two types - 9B and 16B for now */
static const hfi1_make_ruc_hdr hfi1_ruc_header_tbl[2] = {
        [HFI1_PKT_TYPE_9B] = &hfi1_make_ruc_header_9B,
        [HFI1_PKT_TYPE_16B] = &hfi1_make_ruc_header_16B
};

void hfi1_make_ruc_header(struct rvt_qp *qp, struct ib_other_headers *ohdr,
                          u32 bth0, u32 bth1, u32 bth2, int middle,
                          struct hfi1_pkt_state *ps)
{
        struct hfi1_qp_priv *priv = qp->priv;

        /*
         * reset s_ahg/AHG fields
         *
         * This insures that the ahgentry/ahgcount
         * are at a non-AHG default to protect
         * build_verbs_tx_desc() from using
         * an include ahgidx.
         *
         * build_ahg() will modify as appropriate
         * to use the AHG feature.
         */
        priv->s_ahg->tx_flags = 0;
        priv->s_ahg->ahgcount = 0;
        priv->s_ahg->ahgidx = 0;

        /* Make the appropriate header */
        hfi1_ruc_header_tbl[priv->hdr_type](qp, ohdr, bth0, bth1, bth2, middle,
                                            ps);
}

/* when sending, force a reschedule every one of these periods */
#define SEND_RESCHED_TIMEOUT (5 * HZ)  /* 5s in jiffies */

/**
 * hfi1_schedule_send_yield - test for a yield required for QP
 * send engine
 * @timeout: Final time for timeout slice for jiffies
 * @qp: a pointer to QP
 * @ps: a pointer to a structure with commonly lookup values for
 *      the the send engine progress
 * @tid - true if it is the tid leg
 *
 * This routine checks if the time slice for the QP has expired
 * for RC QPs, if so an additional work entry is queued. At this
 * point, other QPs have an opportunity to be scheduled. It
 * returns true if a yield is required, otherwise, false
 * is returned.
 */
bool hfi1_schedule_send_yield(struct rvt_qp *qp, struct hfi1_pkt_state *ps,
                              bool tid)
{
        ps->pkts_sent = true;

        if (unlikely(time_after(jiffies, ps->timeout))) {
                if (!ps->in_thread ||
                    workqueue_congested(ps->cpu, ps->ppd->hfi1_wq)) {
                        spin_lock_irqsave(&qp->s_lock, ps->flags);
                        if (!tid) {
                                qp->s_flags &= ~RVT_S_BUSY;
                                hfi1_schedule_send(qp);
                        } else {
                                struct hfi1_qp_priv *priv = qp->priv;

                                if (priv->s_flags &
                                    HFI1_S_TID_BUSY_SET) {
                                        qp->s_flags &= ~RVT_S_BUSY;
                                        priv->s_flags &=
                                                ~(HFI1_S_TID_BUSY_SET |
                                                  RVT_S_BUSY);
                                } else {
                                        priv->s_flags &= ~RVT_S_BUSY;
                                }
                                hfi1_schedule_tid_send(qp);
                        }

                        spin_unlock_irqrestore(&qp->s_lock, ps->flags);
                        this_cpu_inc(*ps->ppd->dd->send_schedule);
                        trace_hfi1_rc_expired_time_slice(qp, true);
                        return true;
                }

                cond_resched();
                this_cpu_inc(*ps->ppd->dd->send_schedule);
                ps->timeout = jiffies + ps->timeout_int;
        }

        trace_hfi1_rc_expired_time_slice(qp, false);
        return false;
}

void hfi1_do_send_from_rvt(struct rvt_qp *qp)
{
        hfi1_do_send(qp, false);
}

void _hfi1_do_send(struct work_struct *work)
{
        struct iowait_work *w = container_of(work, struct iowait_work, iowork);
        struct rvt_qp *qp = iowait_to_qp(w->iow);

        hfi1_do_send(qp, true);
}

/**
 * hfi1_do_send - perform a send on a QP
 * @qp: a pointer to the QP
 * @in_thread: true if in a workqueue thread
 *
 * Process entries in the send work queue until credit or queue is
 * exhausted.  Only allow one CPU to send a packet per QP.
 * Otherwise, two threads could send packets out of order.
 */
void hfi1_do_send(struct rvt_qp *qp, bool in_thread)
{
        struct hfi1_pkt_state ps;
        struct hfi1_qp_priv *priv = qp->priv;
        int (*make_req)(struct rvt_qp *qp, struct hfi1_pkt_state *ps);

        ps.dev = to_idev(qp->ibqp.device);
        ps.ibp = to_iport(qp->ibqp.device, qp->port_num);
        ps.ppd = ppd_from_ibp(ps.ibp);
        ps.in_thread = in_thread;
        ps.wait = iowait_get_ib_work(&priv->s_iowait);

        trace_hfi1_rc_do_send(qp, in_thread);

        switch (qp->ibqp.qp_type) {
        case IB_QPT_RC:
                if (!loopback && ((rdma_ah_get_dlid(&qp->remote_ah_attr) &
                                   ~((1 << ps.ppd->lmc) - 1)) ==
                                  ps.ppd->lid)) {
                        rvt_ruc_loopback(qp);
                        return;
                }
                make_req = hfi1_make_rc_req;
                ps.timeout_int = qp->timeout_jiffies;
                break;
        case IB_QPT_UC:
                if (!loopback && ((rdma_ah_get_dlid(&qp->remote_ah_attr) &
                                   ~((1 << ps.ppd->lmc) - 1)) ==
                                  ps.ppd->lid)) {
                        rvt_ruc_loopback(qp);
                        return;
                }
                make_req = hfi1_make_uc_req;
                ps.timeout_int = SEND_RESCHED_TIMEOUT;
                break;
        default:
                make_req = hfi1_make_ud_req;
                ps.timeout_int = SEND_RESCHED_TIMEOUT;
        }

        spin_lock_irqsave(&qp->s_lock, ps.flags);

        /* Return if we are already busy processing a work request. */
        if (!hfi1_send_ok(qp)) {
                if (qp->s_flags & HFI1_S_ANY_WAIT_IO)
                        iowait_set_flag(&priv->s_iowait, IOWAIT_PENDING_IB);
                spin_unlock_irqrestore(&qp->s_lock, ps.flags);
                return;
        }

        qp->s_flags |= RVT_S_BUSY;

        ps.timeout_int = ps.timeout_int / 8;
        ps.timeout = jiffies + ps.timeout_int;
        ps.cpu = priv->s_sde ? priv->s_sde->cpu :
                        cpumask_first(cpumask_of_node(ps.ppd->dd->node));
        ps.pkts_sent = false;

        /* insure a pre-built packet is handled  */
        ps.s_txreq = get_waiting_verbs_txreq(ps.wait);
        do {
                /* Check for a constructed packet to be sent. */
                if (ps.s_txreq) {
                        if (priv->s_flags & HFI1_S_TID_BUSY_SET)
                                qp->s_flags |= RVT_S_BUSY;
                        spin_unlock_irqrestore(&qp->s_lock, ps.flags);
                        /*
                         * If the packet cannot be sent now, return and
                         * the send engine will be woken up later.
                         */
                        if (hfi1_verbs_send(qp, &ps))
                                return;

                        /* allow other tasks to run */
                        if (hfi1_schedule_send_yield(qp, &ps, false))
                                return;

                        spin_lock_irqsave(&qp->s_lock, ps.flags);
                }
        } while (make_req(qp, &ps));
        iowait_starve_clear(ps.pkts_sent, &priv->s_iowait);
        spin_unlock_irqrestore(&qp->s_lock, ps.flags);
}