Merge tag 'sched-urgent-2024-03-24' of git://git.kernel.org/pub/scm/linux/kernel...

[sfrench/cifs-2.6.git] / drivers / infiniband / hw / hfi1 / tid_rdma.c

// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
/*
 * Copyright(c) 2018 - 2020 Intel Corporation.
 *
 */

#include "hfi.h"
#include "qp.h"
#include "rc.h"
#include "verbs.h"
#include "tid_rdma.h"
#include "exp_rcv.h"
#include "trace.h"

/**
 * DOC: TID RDMA READ protocol
 *
 * This is an end-to-end protocol at the hfi1 level between two nodes that
 * improves performance by avoiding data copy on the requester side. It
 * converts a qualified RDMA READ request into a TID RDMA READ request on
 * the requester side and thereafter handles the request and response
 * differently. To be qualified, the RDMA READ request should meet the
 * following:
 * -- The total data length should be greater than 256K;
 * -- The total data length should be a multiple of 4K page size;
 * -- Each local scatter-gather entry should be 4K page aligned;
 * -- Each local scatter-gather entry should be a multiple of 4K page size;
 */

#define RCV_TID_FLOW_TABLE_CTRL_FLOW_VALID_SMASK BIT_ULL(32)
#define RCV_TID_FLOW_TABLE_CTRL_HDR_SUPP_EN_SMASK BIT_ULL(33)
#define RCV_TID_FLOW_TABLE_CTRL_KEEP_AFTER_SEQ_ERR_SMASK BIT_ULL(34)
#define RCV_TID_FLOW_TABLE_CTRL_KEEP_ON_GEN_ERR_SMASK BIT_ULL(35)
#define RCV_TID_FLOW_TABLE_STATUS_SEQ_MISMATCH_SMASK BIT_ULL(37)
#define RCV_TID_FLOW_TABLE_STATUS_GEN_MISMATCH_SMASK BIT_ULL(38)

/* Maximum number of packets within a flow generation. */
#define MAX_TID_FLOW_PSN BIT(HFI1_KDETH_BTH_SEQ_SHIFT)

#define GENERATION_MASK 0xFFFFF

static u32 mask_generation(u32 a)
{
        return a & GENERATION_MASK;
}

/* Reserved generation value to set to unused flows for kernel contexts */
#define KERN_GENERATION_RESERVED mask_generation(U32_MAX)

/*
 * J_KEY for kernel contexts when TID RDMA is used.
 * See generate_jkey() in hfi.h for more information.
 */
#define TID_RDMA_JKEY                   32
#define HFI1_KERNEL_MIN_JKEY HFI1_ADMIN_JKEY_RANGE
#define HFI1_KERNEL_MAX_JKEY (2 * HFI1_ADMIN_JKEY_RANGE - 1)

/* Maximum number of segments in flight per QP request. */
#define TID_RDMA_MAX_READ_SEGS_PER_REQ  6
#define TID_RDMA_MAX_WRITE_SEGS_PER_REQ 4
#define MAX_REQ max_t(u16, TID_RDMA_MAX_READ_SEGS_PER_REQ, \
                        TID_RDMA_MAX_WRITE_SEGS_PER_REQ)
#define MAX_FLOWS roundup_pow_of_two(MAX_REQ + 1)

#define MAX_EXPECTED_PAGES     (MAX_EXPECTED_BUFFER / PAGE_SIZE)

#define TID_RDMA_DESTQP_FLOW_SHIFT      11
#define TID_RDMA_DESTQP_FLOW_MASK       0x1f

#define TID_OPFN_QP_CTXT_MASK 0xff
#define TID_OPFN_QP_CTXT_SHIFT 56
#define TID_OPFN_QP_KDETH_MASK 0xff
#define TID_OPFN_QP_KDETH_SHIFT 48
#define TID_OPFN_MAX_LEN_MASK 0x7ff
#define TID_OPFN_MAX_LEN_SHIFT 37
#define TID_OPFN_TIMEOUT_MASK 0x1f
#define TID_OPFN_TIMEOUT_SHIFT 32
#define TID_OPFN_RESERVED_MASK 0x3f
#define TID_OPFN_RESERVED_SHIFT 26
#define TID_OPFN_URG_MASK 0x1
#define TID_OPFN_URG_SHIFT 25
#define TID_OPFN_VER_MASK 0x7
#define TID_OPFN_VER_SHIFT 22
#define TID_OPFN_JKEY_MASK 0x3f
#define TID_OPFN_JKEY_SHIFT 16
#define TID_OPFN_MAX_READ_MASK 0x3f
#define TID_OPFN_MAX_READ_SHIFT 10
#define TID_OPFN_MAX_WRITE_MASK 0x3f
#define TID_OPFN_MAX_WRITE_SHIFT 4

/*
 * OPFN TID layout
 *
 * 63               47               31               15
 * NNNNNNNNKKKKKKKK MMMMMMMMMMMTTTTT DDDDDDUVVVJJJJJJ RRRRRRWWWWWWCCCC
 * 3210987654321098 7654321098765432 1098765432109876 5432109876543210
 * N - the context Number
 * K - the Kdeth_qp
 * M - Max_len
 * T - Timeout
 * D - reserveD
 * V - version
 * U - Urg capable
 * J - Jkey
 * R - max_Read
 * W - max_Write
 * C - Capcode
 */

static void tid_rdma_trigger_resume(struct work_struct *work);
static void hfi1_kern_exp_rcv_free_flows(struct tid_rdma_request *req);
static int hfi1_kern_exp_rcv_alloc_flows(struct tid_rdma_request *req,
                                         gfp_t gfp);
static void hfi1_init_trdma_req(struct rvt_qp *qp,
                                struct tid_rdma_request *req);
static void hfi1_tid_write_alloc_resources(struct rvt_qp *qp, bool intr_ctx);
static void hfi1_tid_timeout(struct timer_list *t);
static void hfi1_add_tid_reap_timer(struct rvt_qp *qp);
static void hfi1_mod_tid_reap_timer(struct rvt_qp *qp);
static void hfi1_mod_tid_retry_timer(struct rvt_qp *qp);
static int hfi1_stop_tid_retry_timer(struct rvt_qp *qp);
static void hfi1_tid_retry_timeout(struct timer_list *t);
static int make_tid_rdma_ack(struct rvt_qp *qp,
                             struct ib_other_headers *ohdr,
                             struct hfi1_pkt_state *ps);
static void hfi1_do_tid_send(struct rvt_qp *qp);
static u32 read_r_next_psn(struct hfi1_devdata *dd, u8 ctxt, u8 fidx);
static void tid_rdma_rcv_err(struct hfi1_packet *packet,
                             struct ib_other_headers *ohdr,
                             struct rvt_qp *qp, u32 psn, int diff, bool fecn);
static void update_r_next_psn_fecn(struct hfi1_packet *packet,
                                   struct hfi1_qp_priv *priv,
                                   struct hfi1_ctxtdata *rcd,
                                   struct tid_rdma_flow *flow,
                                   bool fecn);

static void validate_r_tid_ack(struct hfi1_qp_priv *priv)
{
        if (priv->r_tid_ack == HFI1_QP_WQE_INVALID)
                priv->r_tid_ack = priv->r_tid_tail;
}

static void tid_rdma_schedule_ack(struct rvt_qp *qp)
{
        struct hfi1_qp_priv *priv = qp->priv;

        priv->s_flags |= RVT_S_ACK_PENDING;
        hfi1_schedule_tid_send(qp);
}

static void tid_rdma_trigger_ack(struct rvt_qp *qp)
{
        validate_r_tid_ack(qp->priv);
        tid_rdma_schedule_ack(qp);
}

static u64 tid_rdma_opfn_encode(struct tid_rdma_params *p)
{
        return
                (((u64)p->qp & TID_OPFN_QP_CTXT_MASK) <<
                        TID_OPFN_QP_CTXT_SHIFT) |
                ((((u64)p->qp >> 16) & TID_OPFN_QP_KDETH_MASK) <<
                        TID_OPFN_QP_KDETH_SHIFT) |
                (((u64)((p->max_len >> PAGE_SHIFT) - 1) &
                        TID_OPFN_MAX_LEN_MASK) << TID_OPFN_MAX_LEN_SHIFT) |
                (((u64)p->timeout & TID_OPFN_TIMEOUT_MASK) <<
                        TID_OPFN_TIMEOUT_SHIFT) |
                (((u64)p->urg & TID_OPFN_URG_MASK) << TID_OPFN_URG_SHIFT) |
                (((u64)p->jkey & TID_OPFN_JKEY_MASK) << TID_OPFN_JKEY_SHIFT) |
                (((u64)p->max_read & TID_OPFN_MAX_READ_MASK) <<
                        TID_OPFN_MAX_READ_SHIFT) |
                (((u64)p->max_write & TID_OPFN_MAX_WRITE_MASK) <<
                        TID_OPFN_MAX_WRITE_SHIFT);
}

static void tid_rdma_opfn_decode(struct tid_rdma_params *p, u64 data)
{
        p->max_len = (((data >> TID_OPFN_MAX_LEN_SHIFT) &
                TID_OPFN_MAX_LEN_MASK) + 1) << PAGE_SHIFT;
        p->jkey = (data >> TID_OPFN_JKEY_SHIFT) & TID_OPFN_JKEY_MASK;
        p->max_write = (data >> TID_OPFN_MAX_WRITE_SHIFT) &
                TID_OPFN_MAX_WRITE_MASK;
        p->max_read = (data >> TID_OPFN_MAX_READ_SHIFT) &
                TID_OPFN_MAX_READ_MASK;
        p->qp =
                ((((data >> TID_OPFN_QP_KDETH_SHIFT) & TID_OPFN_QP_KDETH_MASK)
                        << 16) |
                ((data >> TID_OPFN_QP_CTXT_SHIFT) & TID_OPFN_QP_CTXT_MASK));
        p->urg = (data >> TID_OPFN_URG_SHIFT) & TID_OPFN_URG_MASK;
        p->timeout = (data >> TID_OPFN_TIMEOUT_SHIFT) & TID_OPFN_TIMEOUT_MASK;
}

void tid_rdma_opfn_init(struct rvt_qp *qp, struct tid_rdma_params *p)
{
        struct hfi1_qp_priv *priv = qp->priv;

        p->qp = (RVT_KDETH_QP_PREFIX << 16) | priv->rcd->ctxt;
        p->max_len = TID_RDMA_MAX_SEGMENT_SIZE;
        p->jkey = priv->rcd->jkey;
        p->max_read = TID_RDMA_MAX_READ_SEGS_PER_REQ;
        p->max_write = TID_RDMA_MAX_WRITE_SEGS_PER_REQ;
        p->timeout = qp->timeout;
        p->urg = is_urg_masked(priv->rcd);
}

bool tid_rdma_conn_req(struct rvt_qp *qp, u64 *data)
{
        struct hfi1_qp_priv *priv = qp->priv;

        *data = tid_rdma_opfn_encode(&priv->tid_rdma.local);
        return true;
}

bool tid_rdma_conn_reply(struct rvt_qp *qp, u64 data)
{
        struct hfi1_qp_priv *priv = qp->priv;
        struct tid_rdma_params *remote, *old;
        bool ret = true;

        old = rcu_dereference_protected(priv->tid_rdma.remote,
                                        lockdep_is_held(&priv->opfn.lock));
        data &= ~0xfULL;
        /*
         * If data passed in is zero, return true so as not to continue the
         * negotiation process
         */
        if (!data || !HFI1_CAP_IS_KSET(TID_RDMA))
                goto null;
        /*
         * If kzalloc fails, return false. This will result in:
         * * at the requester a new OPFN request being generated to retry
         *   the negotiation
         * * at the responder, 0 being returned to the requester so as to
         *   disable TID RDMA at both the requester and the responder
         */
        remote = kzalloc(sizeof(*remote), GFP_ATOMIC);
        if (!remote) {
                ret = false;
                goto null;
        }

        tid_rdma_opfn_decode(remote, data);
        priv->tid_timer_timeout_jiffies =
                usecs_to_jiffies((((4096UL * (1UL << remote->timeout)) /
                                   1000UL) << 3) * 7);
        trace_hfi1_opfn_param(qp, 0, &priv->tid_rdma.local);
        trace_hfi1_opfn_param(qp, 1, remote);
        rcu_assign_pointer(priv->tid_rdma.remote, remote);
        /*
         * A TID RDMA READ request's segment size is not equal to
         * remote->max_len only when the request's data length is smaller
         * than remote->max_len. In that case, there will be only one segment.
         * Therefore, when priv->pkts_ps is used to calculate req->cur_seg
         * during retry, it will lead to req->cur_seg = 0, which is exactly
         * what is expected.
         */
        priv->pkts_ps = (u16)rvt_div_mtu(qp, remote->max_len);
        priv->timeout_shift = ilog2(priv->pkts_ps - 1) + 1;
        goto free;
null:
        RCU_INIT_POINTER(priv->tid_rdma.remote, NULL);
        priv->timeout_shift = 0;
free:
        if (old)
                kfree_rcu(old, rcu_head);
        return ret;
}

bool tid_rdma_conn_resp(struct rvt_qp *qp, u64 *data)
{
        bool ret;

        ret = tid_rdma_conn_reply(qp, *data);
        *data = 0;
        /*
         * If tid_rdma_conn_reply() returns error, set *data as 0 to indicate
         * TID RDMA could not be enabled. This will result in TID RDMA being
         * disabled at the requester too.
         */
        if (ret)
                (void)tid_rdma_conn_req(qp, data);
        return ret;
}

void tid_rdma_conn_error(struct rvt_qp *qp)
{
        struct hfi1_qp_priv *priv = qp->priv;
        struct tid_rdma_params *old;

        old = rcu_dereference_protected(priv->tid_rdma.remote,
                                        lockdep_is_held(&priv->opfn.lock));
        RCU_INIT_POINTER(priv->tid_rdma.remote, NULL);
        if (old)
                kfree_rcu(old, rcu_head);
}

/* This is called at context initialization time */
int hfi1_kern_exp_rcv_init(struct hfi1_ctxtdata *rcd, int reinit)
{
        if (reinit)
                return 0;

        BUILD_BUG_ON(TID_RDMA_JKEY < HFI1_KERNEL_MIN_JKEY);
        BUILD_BUG_ON(TID_RDMA_JKEY > HFI1_KERNEL_MAX_JKEY);
        rcd->jkey = TID_RDMA_JKEY;
        hfi1_set_ctxt_jkey(rcd->dd, rcd, rcd->jkey);
        return hfi1_alloc_ctxt_rcv_groups(rcd);
}

/**
 * qp_to_rcd - determine the receive context used by a qp
 * @rdi: rvt dev struct
 * @qp: the qp
 *
 * This routine returns the receive context associated
 * with a a qp's qpn.
 *
 * Return: the context.
 */
static struct hfi1_ctxtdata *qp_to_rcd(struct rvt_dev_info *rdi,
                                       struct rvt_qp *qp)
{
        struct hfi1_ibdev *verbs_dev = container_of(rdi,
                                                    struct hfi1_ibdev,
                                                    rdi);
        struct hfi1_devdata *dd = container_of(verbs_dev,
                                               struct hfi1_devdata,
                                               verbs_dev);
        unsigned int ctxt;

        if (qp->ibqp.qp_num == 0)
                ctxt = 0;
        else
                ctxt = hfi1_get_qp_map(dd, qp->ibqp.qp_num >> dd->qos_shift);
        return dd->rcd[ctxt];
}

int hfi1_qp_priv_init(struct rvt_dev_info *rdi, struct rvt_qp *qp,
                      struct ib_qp_init_attr *init_attr)
{
        struct hfi1_qp_priv *qpriv = qp->priv;
        int i, ret;

        qpriv->rcd = qp_to_rcd(rdi, qp);

        spin_lock_init(&qpriv->opfn.lock);
        INIT_WORK(&qpriv->opfn.opfn_work, opfn_send_conn_request);
        INIT_WORK(&qpriv->tid_rdma.trigger_work, tid_rdma_trigger_resume);
        qpriv->flow_state.psn = 0;
        qpriv->flow_state.index = RXE_NUM_TID_FLOWS;
        qpriv->flow_state.last_index = RXE_NUM_TID_FLOWS;
        qpriv->flow_state.generation = KERN_GENERATION_RESERVED;
        qpriv->s_state = TID_OP(WRITE_RESP);
        qpriv->s_tid_cur = HFI1_QP_WQE_INVALID;
        qpriv->s_tid_head = HFI1_QP_WQE_INVALID;
        qpriv->s_tid_tail = HFI1_QP_WQE_INVALID;
        qpriv->rnr_nak_state = TID_RNR_NAK_INIT;
        qpriv->r_tid_head = HFI1_QP_WQE_INVALID;
        qpriv->r_tid_tail = HFI1_QP_WQE_INVALID;
        qpriv->r_tid_ack = HFI1_QP_WQE_INVALID;
        qpriv->r_tid_alloc = HFI1_QP_WQE_INVALID;
        atomic_set(&qpriv->n_requests, 0);
        atomic_set(&qpriv->n_tid_requests, 0);
        timer_setup(&qpriv->s_tid_timer, hfi1_tid_timeout, 0);
        timer_setup(&qpriv->s_tid_retry_timer, hfi1_tid_retry_timeout, 0);
        INIT_LIST_HEAD(&qpriv->tid_wait);

        if (init_attr->qp_type == IB_QPT_RC && HFI1_CAP_IS_KSET(TID_RDMA)) {
                struct hfi1_devdata *dd = qpriv->rcd->dd;

                qpriv->pages = kzalloc_node(TID_RDMA_MAX_PAGES *
                                                sizeof(*qpriv->pages),
                                            GFP_KERNEL, dd->node);
                if (!qpriv->pages)
                        return -ENOMEM;
                for (i = 0; i < qp->s_size; i++) {
                        struct hfi1_swqe_priv *priv;
                        struct rvt_swqe *wqe = rvt_get_swqe_ptr(qp, i);

                        priv = kzalloc_node(sizeof(*priv), GFP_KERNEL,
                                            dd->node);
                        if (!priv)
                                return -ENOMEM;

                        hfi1_init_trdma_req(qp, &priv->tid_req);
                        priv->tid_req.e.swqe = wqe;
                        wqe->priv = priv;
                }
                for (i = 0; i < rvt_max_atomic(rdi); i++) {
                        struct hfi1_ack_priv *priv;

                        priv = kzalloc_node(sizeof(*priv), GFP_KERNEL,
                                            dd->node);
                        if (!priv)
                                return -ENOMEM;

                        hfi1_init_trdma_req(qp, &priv->tid_req);
                        priv->tid_req.e.ack = &qp->s_ack_queue[i];

                        ret = hfi1_kern_exp_rcv_alloc_flows(&priv->tid_req,
                                                            GFP_KERNEL);
                        if (ret) {
                                kfree(priv);
                                return ret;
                        }
                        qp->s_ack_queue[i].priv = priv;
                }
        }

        return 0;
}

void hfi1_qp_priv_tid_free(struct rvt_dev_info *rdi, struct rvt_qp *qp)
{
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct rvt_swqe *wqe;
        u32 i;

        if (qp->ibqp.qp_type == IB_QPT_RC && HFI1_CAP_IS_KSET(TID_RDMA)) {
                for (i = 0; i < qp->s_size; i++) {
                        wqe = rvt_get_swqe_ptr(qp, i);
                        kfree(wqe->priv);
                        wqe->priv = NULL;
                }
                for (i = 0; i < rvt_max_atomic(rdi); i++) {
                        struct hfi1_ack_priv *priv = qp->s_ack_queue[i].priv;

                        if (priv)
                                hfi1_kern_exp_rcv_free_flows(&priv->tid_req);
                        kfree(priv);
                        qp->s_ack_queue[i].priv = NULL;
                }
                cancel_work_sync(&qpriv->opfn.opfn_work);
                kfree(qpriv->pages);
                qpriv->pages = NULL;
        }
}

/* Flow and tid waiter functions */
/**
 * DOC: lock ordering
 *
 * There are two locks involved with the queuing
 * routines: the qp s_lock and the exp_lock.
 *
 * Since the tid space allocation is called from
 * the send engine, the qp s_lock is already held.
 *
 * The allocation routines will get the exp_lock.
 *
 * The first_qp() call is provided to allow the head of
 * the rcd wait queue to be fetched under the exp_lock and
 * followed by a drop of the exp_lock.
 *
 * Any qp in the wait list will have the qp reference count held
 * to hold the qp in memory.
 */

/*
 * return head of rcd wait list
 *
 * Must hold the exp_lock.
 *
 * Get a reference to the QP to hold the QP in memory.
 *
 * The caller must release the reference when the local
 * is no longer being used.
 */
static struct rvt_qp *first_qp(struct hfi1_ctxtdata *rcd,
                               struct tid_queue *queue)
        __must_hold(&rcd->exp_lock)
{
        struct hfi1_qp_priv *priv;

        lockdep_assert_held(&rcd->exp_lock);
        priv = list_first_entry_or_null(&queue->queue_head,
                                        struct hfi1_qp_priv,
                                        tid_wait);
        if (!priv)
                return NULL;
        rvt_get_qp(priv->owner);
        return priv->owner;
}

/**
 * kernel_tid_waiters - determine rcd wait
 * @rcd: the receive context
 * @queue: the queue to operate on
 * @qp: the head of the qp being processed
 *
 * This routine will return false IFF
 * the list is NULL or the head of the
 * list is the indicated qp.
 *
 * Must hold the qp s_lock and the exp_lock.
 *
 * Return:
 * false if either of the conditions below are satisfied:
 * 1. The list is empty or
 * 2. The indicated qp is at the head of the list and the
 *    HFI1_S_WAIT_TID_SPACE bit is set in qp->s_flags.
 * true is returned otherwise.
 */
static bool kernel_tid_waiters(struct hfi1_ctxtdata *rcd,
                               struct tid_queue *queue, struct rvt_qp *qp)
        __must_hold(&rcd->exp_lock) __must_hold(&qp->s_lock)
{
        struct rvt_qp *fqp;
        bool ret = true;

        lockdep_assert_held(&qp->s_lock);
        lockdep_assert_held(&rcd->exp_lock);
        fqp = first_qp(rcd, queue);
        if (!fqp || (fqp == qp && (qp->s_flags & HFI1_S_WAIT_TID_SPACE)))
                ret = false;
        rvt_put_qp(fqp);
        return ret;
}

/**
 * dequeue_tid_waiter - dequeue the qp from the list
 * @rcd: the receive context
 * @queue: the queue to operate on
 * @qp: the qp to remove the wait list
 *
 * This routine removes the indicated qp from the
 * wait list if it is there.
 *
 * This should be done after the hardware flow and
 * tid array resources have been allocated.
 *
 * Must hold the qp s_lock and the rcd exp_lock.
 *
 * It assumes the s_lock to protect the s_flags
 * field and to reliably test the HFI1_S_WAIT_TID_SPACE flag.
 */
static void dequeue_tid_waiter(struct hfi1_ctxtdata *rcd,
                               struct tid_queue *queue, struct rvt_qp *qp)
        __must_hold(&rcd->exp_lock) __must_hold(&qp->s_lock)
{
        struct hfi1_qp_priv *priv = qp->priv;

        lockdep_assert_held(&qp->s_lock);
        lockdep_assert_held(&rcd->exp_lock);
        if (list_empty(&priv->tid_wait))
                return;
        list_del_init(&priv->tid_wait);
        qp->s_flags &= ~HFI1_S_WAIT_TID_SPACE;
        queue->dequeue++;
        rvt_put_qp(qp);
}

/**
 * queue_qp_for_tid_wait - suspend QP on tid space
 * @rcd: the receive context
 * @queue: the queue to operate on
 * @qp: the qp
 *
 * The qp is inserted at the tail of the rcd
 * wait queue and the HFI1_S_WAIT_TID_SPACE s_flag is set.
 *
 * Must hold the qp s_lock and the exp_lock.
 */
static void queue_qp_for_tid_wait(struct hfi1_ctxtdata *rcd,
                                  struct tid_queue *queue, struct rvt_qp *qp)
        __must_hold(&rcd->exp_lock) __must_hold(&qp->s_lock)
{
        struct hfi1_qp_priv *priv = qp->priv;

        lockdep_assert_held(&qp->s_lock);
        lockdep_assert_held(&rcd->exp_lock);
        if (list_empty(&priv->tid_wait)) {
                qp->s_flags |= HFI1_S_WAIT_TID_SPACE;
                list_add_tail(&priv->tid_wait, &queue->queue_head);
                priv->tid_enqueue = ++queue->enqueue;
                rcd->dd->verbs_dev.n_tidwait++;
                trace_hfi1_qpsleep(qp, HFI1_S_WAIT_TID_SPACE);
                rvt_get_qp(qp);
        }
}

/**
 * __trigger_tid_waiter - trigger tid waiter
 * @qp: the qp
 *
 * This is a private entrance to schedule the qp
 * assuming the caller is holding the qp->s_lock.
 */
static void __trigger_tid_waiter(struct rvt_qp *qp)
        __must_hold(&qp->s_lock)
{
        lockdep_assert_held(&qp->s_lock);
        if (!(qp->s_flags & HFI1_S_WAIT_TID_SPACE))
                return;
        trace_hfi1_qpwakeup(qp, HFI1_S_WAIT_TID_SPACE);
        hfi1_schedule_send(qp);
}

/**
 * tid_rdma_schedule_tid_wakeup - schedule wakeup for a qp
 * @qp: the qp
 *
 * trigger a schedule or a waiting qp in a deadlock
 * safe manner.  The qp reference is held prior
 * to this call via first_qp().
 *
 * If the qp trigger was already scheduled (!rval)
 * the reference is dropped, otherwise the resume
 * or the destroy cancel will dispatch the reference.
 */
static void tid_rdma_schedule_tid_wakeup(struct rvt_qp *qp)
{
        struct hfi1_qp_priv *priv;
        struct hfi1_ibport *ibp;
        struct hfi1_pportdata *ppd;
        struct hfi1_devdata *dd;
        bool rval;

        if (!qp)
                return;

        priv = qp->priv;
        ibp = to_iport(qp->ibqp.device, qp->port_num);
        ppd = ppd_from_ibp(ibp);
        dd = dd_from_ibdev(qp->ibqp.device);

        rval = queue_work_on(priv->s_sde ?
                             priv->s_sde->cpu :
                             cpumask_first(cpumask_of_node(dd->node)),
                             ppd->hfi1_wq,
                             &priv->tid_rdma.trigger_work);
        if (!rval)
                rvt_put_qp(qp);
}

/**
 * tid_rdma_trigger_resume - field a trigger work request
 * @work: the work item
 *
 * Complete the off qp trigger processing by directly
 * calling the progress routine.
 */
static void tid_rdma_trigger_resume(struct work_struct *work)
{
        struct tid_rdma_qp_params *tr;
        struct hfi1_qp_priv *priv;
        struct rvt_qp *qp;

        tr = container_of(work, struct tid_rdma_qp_params, trigger_work);
        priv = container_of(tr, struct hfi1_qp_priv, tid_rdma);
        qp = priv->owner;
        spin_lock_irq(&qp->s_lock);
        if (qp->s_flags & HFI1_S_WAIT_TID_SPACE) {
                spin_unlock_irq(&qp->s_lock);
                hfi1_do_send(priv->owner, true);
        } else {
                spin_unlock_irq(&qp->s_lock);
        }
        rvt_put_qp(qp);
}

/*
 * tid_rdma_flush_wait - unwind any tid space wait
 *
 * This is called when resetting a qp to
 * allow a destroy or reset to get rid
 * of any tid space linkage and reference counts.
 */
static void _tid_rdma_flush_wait(struct rvt_qp *qp, struct tid_queue *queue)
        __must_hold(&qp->s_lock)
{
        struct hfi1_qp_priv *priv;

        if (!qp)
                return;
        lockdep_assert_held(&qp->s_lock);
        priv = qp->priv;
        qp->s_flags &= ~HFI1_S_WAIT_TID_SPACE;
        spin_lock(&priv->rcd->exp_lock);
        if (!list_empty(&priv->tid_wait)) {
                list_del_init(&priv->tid_wait);
                qp->s_flags &= ~HFI1_S_WAIT_TID_SPACE;
                queue->dequeue++;
                rvt_put_qp(qp);
        }
        spin_unlock(&priv->rcd->exp_lock);
}

void hfi1_tid_rdma_flush_wait(struct rvt_qp *qp)
        __must_hold(&qp->s_lock)
{
        struct hfi1_qp_priv *priv = qp->priv;

        _tid_rdma_flush_wait(qp, &priv->rcd->flow_queue);
        _tid_rdma_flush_wait(qp, &priv->rcd->rarr_queue);
}

/* Flow functions */
/**
 * kern_reserve_flow - allocate a hardware flow
 * @rcd: the context to use for allocation
 * @last: the index of the preferred flow. Use RXE_NUM_TID_FLOWS to
 *         signify "don't care".
 *
 * Use a bit mask based allocation to reserve a hardware
 * flow for use in receiving KDETH data packets. If a preferred flow is
 * specified the function will attempt to reserve that flow again, if
 * available.
 *
 * The exp_lock must be held.
 *
 * Return:
 * On success: a value positive value between 0 and RXE_NUM_TID_FLOWS - 1
 * On failure: -EAGAIN
 */
static int kern_reserve_flow(struct hfi1_ctxtdata *rcd, int last)
        __must_hold(&rcd->exp_lock)
{
        int nr;

        /* Attempt to reserve the preferred flow index */
        if (last >= 0 && last < RXE_NUM_TID_FLOWS &&
            !test_and_set_bit(last, &rcd->flow_mask))
                return last;

        nr = ffz(rcd->flow_mask);
        BUILD_BUG_ON(RXE_NUM_TID_FLOWS >=
                     (sizeof(rcd->flow_mask) * BITS_PER_BYTE));
        if (nr > (RXE_NUM_TID_FLOWS - 1))
                return -EAGAIN;
        set_bit(nr, &rcd->flow_mask);
        return nr;
}

static void kern_set_hw_flow(struct hfi1_ctxtdata *rcd, u32 generation,
                             u32 flow_idx)
{
        u64 reg;

        reg = ((u64)generation << HFI1_KDETH_BTH_SEQ_SHIFT) |
                RCV_TID_FLOW_TABLE_CTRL_FLOW_VALID_SMASK |
                RCV_TID_FLOW_TABLE_CTRL_KEEP_AFTER_SEQ_ERR_SMASK |
                RCV_TID_FLOW_TABLE_CTRL_KEEP_ON_GEN_ERR_SMASK |
                RCV_TID_FLOW_TABLE_STATUS_SEQ_MISMATCH_SMASK |
                RCV_TID_FLOW_TABLE_STATUS_GEN_MISMATCH_SMASK;

        if (generation != KERN_GENERATION_RESERVED)
                reg |= RCV_TID_FLOW_TABLE_CTRL_HDR_SUPP_EN_SMASK;

        write_uctxt_csr(rcd->dd, rcd->ctxt,
                        RCV_TID_FLOW_TABLE + 8 * flow_idx, reg);
}

static u32 kern_setup_hw_flow(struct hfi1_ctxtdata *rcd, u32 flow_idx)
        __must_hold(&rcd->exp_lock)
{
        u32 generation = rcd->flows[flow_idx].generation;

        kern_set_hw_flow(rcd, generation, flow_idx);
        return generation;
}

static u32 kern_flow_generation_next(u32 gen)
{
        u32 generation = mask_generation(gen + 1);

        if (generation == KERN_GENERATION_RESERVED)
                generation = mask_generation(generation + 1);
        return generation;
}

static void kern_clear_hw_flow(struct hfi1_ctxtdata *rcd, u32 flow_idx)
        __must_hold(&rcd->exp_lock)
{
        rcd->flows[flow_idx].generation =
                kern_flow_generation_next(rcd->flows[flow_idx].generation);
        kern_set_hw_flow(rcd, KERN_GENERATION_RESERVED, flow_idx);
}

int hfi1_kern_setup_hw_flow(struct hfi1_ctxtdata *rcd, struct rvt_qp *qp)
{
        struct hfi1_qp_priv *qpriv = (struct hfi1_qp_priv *)qp->priv;
        struct tid_flow_state *fs = &qpriv->flow_state;
        struct rvt_qp *fqp;
        unsigned long flags;
        int ret = 0;

        /* The QP already has an allocated flow */
        if (fs->index != RXE_NUM_TID_FLOWS)
                return ret;

        spin_lock_irqsave(&rcd->exp_lock, flags);
        if (kernel_tid_waiters(rcd, &rcd->flow_queue, qp))
                goto queue;

        ret = kern_reserve_flow(rcd, fs->last_index);
        if (ret < 0)
                goto queue;
        fs->index = ret;
        fs->last_index = fs->index;

        /* Generation received in a RESYNC overrides default flow generation */
        if (fs->generation != KERN_GENERATION_RESERVED)
                rcd->flows[fs->index].generation = fs->generation;
        fs->generation = kern_setup_hw_flow(rcd, fs->index);
        fs->psn = 0;
        dequeue_tid_waiter(rcd, &rcd->flow_queue, qp);
        /* get head before dropping lock */
        fqp = first_qp(rcd, &rcd->flow_queue);
        spin_unlock_irqrestore(&rcd->exp_lock, flags);

        tid_rdma_schedule_tid_wakeup(fqp);
        return 0;
queue:
        queue_qp_for_tid_wait(rcd, &rcd->flow_queue, qp);
        spin_unlock_irqrestore(&rcd->exp_lock, flags);
        return -EAGAIN;
}

void hfi1_kern_clear_hw_flow(struct hfi1_ctxtdata *rcd, struct rvt_qp *qp)
{
        struct hfi1_qp_priv *qpriv = (struct hfi1_qp_priv *)qp->priv;
        struct tid_flow_state *fs = &qpriv->flow_state;
        struct rvt_qp *fqp;
        unsigned long flags;

        if (fs->index >= RXE_NUM_TID_FLOWS)
                return;
        spin_lock_irqsave(&rcd->exp_lock, flags);
        kern_clear_hw_flow(rcd, fs->index);
        clear_bit(fs->index, &rcd->flow_mask);
        fs->index = RXE_NUM_TID_FLOWS;
        fs->psn = 0;
        fs->generation = KERN_GENERATION_RESERVED;

        /* get head before dropping lock */
        fqp = first_qp(rcd, &rcd->flow_queue);
        spin_unlock_irqrestore(&rcd->exp_lock, flags);

        if (fqp == qp) {
                __trigger_tid_waiter(fqp);
                rvt_put_qp(fqp);
        } else {
                tid_rdma_schedule_tid_wakeup(fqp);
        }
}

void hfi1_kern_init_ctxt_generations(struct hfi1_ctxtdata *rcd)
{
        int i;

        for (i = 0; i < RXE_NUM_TID_FLOWS; i++) {
                rcd->flows[i].generation = mask_generation(get_random_u32());
                kern_set_hw_flow(rcd, KERN_GENERATION_RESERVED, i);
        }
}

/* TID allocation functions */
static u8 trdma_pset_order(struct tid_rdma_pageset *s)
{
        u8 count = s->count;

        return ilog2(count) + 1;
}

/**
 * tid_rdma_find_phys_blocks_4k - get groups base on mr info
 * @flow: overall info for a TID RDMA segment
 * @pages: pointer to an array of page structs
 * @npages: number of pages
 * @list: page set array to return
 *
 * This routine returns the number of groups associated with
 * the current sge information.  This implementation is based
 * on the expected receive find_phys_blocks() adjusted to
 * use the MR information vs. the pfn.
 *
 * Return:
 * the number of RcvArray entries
 */
static u32 tid_rdma_find_phys_blocks_4k(struct tid_rdma_flow *flow,
                                        struct page **pages,
                                        u32 npages,
                                        struct tid_rdma_pageset *list)
{
        u32 pagecount, pageidx, setcount = 0, i;
        void *vaddr, *this_vaddr;

        if (!npages)
                return 0;

        /*
         * Look for sets of physically contiguous pages in the user buffer.
         * This will allow us to optimize Expected RcvArray entry usage by
         * using the bigger supported sizes.
         */
        vaddr = page_address(pages[0]);
        trace_hfi1_tid_flow_page(flow->req->qp, flow, 0, 0, 0, vaddr);
        for (pageidx = 0, pagecount = 1, i = 1; i <= npages; i++) {
                this_vaddr = i < npages ? page_address(pages[i]) : NULL;
                trace_hfi1_tid_flow_page(flow->req->qp, flow, i, 0, 0,
                                         this_vaddr);
                /*
                 * If the vaddr's are not sequential, pages are not physically
                 * contiguous.
                 */
                if (this_vaddr != (vaddr + PAGE_SIZE)) {
                        /*
                         * At this point we have to loop over the set of
                         * physically contiguous pages and break them down it
                         * sizes supported by the HW.
                         * There are two main constraints:
                         *     1. The max buffer size is MAX_EXPECTED_BUFFER.
                         *        If the total set size is bigger than that
                         *        program only a MAX_EXPECTED_BUFFER chunk.
                         *     2. The buffer size has to be a power of two. If
                         *        it is not, round down to the closes power of
                         *        2 and program that size.
                         */
                        while (pagecount) {
                                int maxpages = pagecount;
                                u32 bufsize = pagecount * PAGE_SIZE;

                                if (bufsize > MAX_EXPECTED_BUFFER)
                                        maxpages =
                                                MAX_EXPECTED_BUFFER >>
                                                PAGE_SHIFT;
                                else if (!is_power_of_2(bufsize))
                                        maxpages =
                                                rounddown_pow_of_two(bufsize) >>
                                                PAGE_SHIFT;

                                list[setcount].idx = pageidx;
                                list[setcount].count = maxpages;
                                trace_hfi1_tid_pageset(flow->req->qp, setcount,
                                                       list[setcount].idx,
                                                       list[setcount].count);
                                pagecount -= maxpages;
                                pageidx += maxpages;
                                setcount++;
                        }
                        pageidx = i;
                        pagecount = 1;
                        vaddr = this_vaddr;
                } else {
                        vaddr += PAGE_SIZE;
                        pagecount++;
                }
        }
        /* insure we always return an even number of sets */
        if (setcount & 1)
                list[setcount++].count = 0;
        return setcount;
}

/**
 * tid_flush_pages - dump out pages into pagesets
 * @list: list of pagesets
 * @idx: pointer to current page index
 * @pages: number of pages to dump
 * @sets: current number of pagesset
 *
 * This routine flushes out accumuated pages.
 *
 * To insure an even number of sets the
 * code may add a filler.
 *
 * This can happen with when pages is not
 * a power of 2 or pages is a power of 2
 * less than the maximum pages.
 *
 * Return:
 * The new number of sets
 */

static u32 tid_flush_pages(struct tid_rdma_pageset *list,
                           u32 *idx, u32 pages, u32 sets)
{
        while (pages) {
                u32 maxpages = pages;

                if (maxpages > MAX_EXPECTED_PAGES)
                        maxpages = MAX_EXPECTED_PAGES;
                else if (!is_power_of_2(maxpages))
                        maxpages = rounddown_pow_of_two(maxpages);
                list[sets].idx = *idx;
                list[sets++].count = maxpages;
                *idx += maxpages;
                pages -= maxpages;
        }
        /* might need a filler */
        if (sets & 1)
                list[sets++].count = 0;
        return sets;
}

/**
 * tid_rdma_find_phys_blocks_8k - get groups base on mr info
 * @flow: overall info for a TID RDMA segment
 * @pages: pointer to an array of page structs
 * @npages: number of pages
 * @list: page set array to return
 *
 * This routine parses an array of pages to compute pagesets
 * in an 8k compatible way.
 *
 * pages are tested two at a time, i, i + 1 for contiguous
 * pages and i - 1 and i contiguous pages.
 *
 * If any condition is false, any accumulated pages are flushed and
 * v0,v1 are emitted as separate PAGE_SIZE pagesets
 *
 * Otherwise, the current 8k is totaled for a future flush.
 *
 * Return:
 * The number of pagesets
 * list set with the returned number of pagesets
 *
 */
static u32 tid_rdma_find_phys_blocks_8k(struct tid_rdma_flow *flow,
                                        struct page **pages,
                                        u32 npages,
                                        struct tid_rdma_pageset *list)
{
        u32 idx, sets = 0, i;
        u32 pagecnt = 0;
        void *v0, *v1, *vm1;

        if (!npages)
                return 0;
        for (idx = 0, i = 0, vm1 = NULL; i < npages; i += 2) {
                /* get a new v0 */
                v0 = page_address(pages[i]);
                trace_hfi1_tid_flow_page(flow->req->qp, flow, i, 1, 0, v0);
                v1 = i + 1 < npages ?
                                page_address(pages[i + 1]) : NULL;
                trace_hfi1_tid_flow_page(flow->req->qp, flow, i, 1, 1, v1);
                /* compare i, i + 1 vaddr */
                if (v1 != (v0 + PAGE_SIZE)) {
                        /* flush out pages */
                        sets = tid_flush_pages(list, &idx, pagecnt, sets);
                        /* output v0,v1 as two pagesets */
                        list[sets].idx = idx++;
                        list[sets++].count = 1;
                        if (v1) {
                                list[sets].count = 1;
                                list[sets++].idx = idx++;
                        } else {
                                list[sets++].count = 0;
                        }
                        vm1 = NULL;
                        pagecnt = 0;
                        continue;
                }
                /* i,i+1 consecutive, look at i-1,i */
                if (vm1 && v0 != (vm1 + PAGE_SIZE)) {
                        /* flush out pages */
                        sets = tid_flush_pages(list, &idx, pagecnt, sets);
                        pagecnt = 0;
                }
                /* pages will always be a multiple of 8k */
                pagecnt += 2;
                /* save i-1 */
                vm1 = v1;
                /* move to next pair */
        }
        /* dump residual pages at end */
        sets = tid_flush_pages(list, &idx, npages - idx, sets);
        /* by design cannot be odd sets */
        WARN_ON(sets & 1);
        return sets;
}

/*
 * Find pages for one segment of a sge array represented by @ss. The function
 * does not check the sge, the sge must have been checked for alignment with a
 * prior call to hfi1_kern_trdma_ok. Other sge checking is done as part of
 * rvt_lkey_ok and rvt_rkey_ok. Also, the function only modifies the local sge
 * copy maintained in @ss->sge, the original sge is not modified.
 *
 * Unlike IB RDMA WRITE, we can't decrement ss->num_sge here because we are not
 * releasing the MR reference count at the same time. Otherwise, we'll "leak"
 * references to the MR. This difference requires that we keep track of progress
 * into the sg_list. This is done by the cur_seg cursor in the tid_rdma_request
 * structure.
 */
static u32 kern_find_pages(struct tid_rdma_flow *flow,
                           struct page **pages,
                           struct rvt_sge_state *ss, bool *last)
{
        struct tid_rdma_request *req = flow->req;
        struct rvt_sge *sge = &ss->sge;
        u32 length = flow->req->seg_len;
        u32 len = PAGE_SIZE;
        u32 i = 0;

        while (length && req->isge < ss->num_sge) {
                pages[i++] = virt_to_page(sge->vaddr);

                sge->vaddr += len;
                sge->length -= len;
                sge->sge_length -= len;
                if (!sge->sge_length) {
                        if (++req->isge < ss->num_sge)
                                *sge = ss->sg_list[req->isge - 1];
                } else if (sge->length == 0 && sge->mr->lkey) {
                        if (++sge->n >= RVT_SEGSZ) {
                                ++sge->m;
                                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;
                }
                length -= len;
        }

        flow->length = flow->req->seg_len - length;
        *last = req->isge != ss->num_sge;
        return i;
}

static void dma_unmap_flow(struct tid_rdma_flow *flow)
{
        struct hfi1_devdata *dd;
        int i;
        struct tid_rdma_pageset *pset;

        dd = flow->req->rcd->dd;
        for (i = 0, pset = &flow->pagesets[0]; i < flow->npagesets;
                        i++, pset++) {
                if (pset->count && pset->addr) {
                        dma_unmap_page(&dd->pcidev->dev,
                                       pset->addr,
                                       PAGE_SIZE * pset->count,
                                       DMA_FROM_DEVICE);
                        pset->mapped = 0;
                }
        }
}

static int dma_map_flow(struct tid_rdma_flow *flow, struct page **pages)
{
        int i;
        struct hfi1_devdata *dd = flow->req->rcd->dd;
        struct tid_rdma_pageset *pset;

        for (i = 0, pset = &flow->pagesets[0]; i < flow->npagesets;
                        i++, pset++) {
                if (pset->count) {
                        pset->addr = dma_map_page(&dd->pcidev->dev,
                                                  pages[pset->idx],
                                                  0,
                                                  PAGE_SIZE * pset->count,
                                                  DMA_FROM_DEVICE);

                        if (dma_mapping_error(&dd->pcidev->dev, pset->addr)) {
                                dma_unmap_flow(flow);
                                return -ENOMEM;
                        }
                        pset->mapped = 1;
                }
        }
        return 0;
}

static inline bool dma_mapped(struct tid_rdma_flow *flow)
{
        return !!flow->pagesets[0].mapped;
}

/*
 * Get pages pointers and identify contiguous physical memory chunks for a
 * segment. All segments are of length flow->req->seg_len.
 */
static int kern_get_phys_blocks(struct tid_rdma_flow *flow,
                                struct page **pages,
                                struct rvt_sge_state *ss, bool *last)
{
        u8 npages;

        /* Reuse previously computed pagesets, if any */
        if (flow->npagesets) {
                trace_hfi1_tid_flow_alloc(flow->req->qp, flow->req->setup_head,
                                          flow);
                if (!dma_mapped(flow))
                        return dma_map_flow(flow, pages);
                return 0;
        }

        npages = kern_find_pages(flow, pages, ss, last);

        if (flow->req->qp->pmtu == enum_to_mtu(OPA_MTU_4096))
                flow->npagesets =
                        tid_rdma_find_phys_blocks_4k(flow, pages, npages,
                                                     flow->pagesets);
        else
                flow->npagesets =
                        tid_rdma_find_phys_blocks_8k(flow, pages, npages,
                                                     flow->pagesets);

        return dma_map_flow(flow, pages);
}

static inline void kern_add_tid_node(struct tid_rdma_flow *flow,
                                     struct hfi1_ctxtdata *rcd, char *s,
                                     struct tid_group *grp, u8 cnt)
{
        struct kern_tid_node *node = &flow->tnode[flow->tnode_cnt++];

        WARN_ON_ONCE(flow->tnode_cnt >=
                     (TID_RDMA_MAX_SEGMENT_SIZE >> PAGE_SHIFT));
        if (WARN_ON_ONCE(cnt & 1))
                dd_dev_err(rcd->dd,
                           "unexpected odd allocation cnt %u map 0x%x used %u",
                           cnt, grp->map, grp->used);

        node->grp = grp;
        node->map = grp->map;
        node->cnt = cnt;
        trace_hfi1_tid_node_add(flow->req->qp, s, flow->tnode_cnt - 1,
                                grp->base, grp->map, grp->used, cnt);
}

/*
 * Try to allocate pageset_count TID's from TID groups for a context
 *
 * This function allocates TID's without moving groups between lists or
 * modifying grp->map. This is done as follows, being cogizant of the lists
 * between which the TID groups will move:
 * 1. First allocate complete groups of 8 TID's since this is more efficient,
 *    these groups will move from group->full without affecting used
 * 2. If more TID's are needed allocate from used (will move from used->full or
 *    stay in used)
 * 3. If we still don't have the required number of TID's go back and look again
 *    at a complete group (will move from group->used)
 */
static int kern_alloc_tids(struct tid_rdma_flow *flow)
{
        struct hfi1_ctxtdata *rcd = flow->req->rcd;
        struct hfi1_devdata *dd = rcd->dd;
        u32 ngroups, pageidx = 0;
        struct tid_group *group = NULL, *used;
        u8 use;

        flow->tnode_cnt = 0;
        ngroups = flow->npagesets / dd->rcv_entries.group_size;
        if (!ngroups)
                goto used_list;

        /* First look at complete groups */
        list_for_each_entry(group,  &rcd->tid_group_list.list, list) {
                kern_add_tid_node(flow, rcd, "complete groups", group,
                                  group->size);

                pageidx += group->size;
                if (!--ngroups)
                        break;
        }

        if (pageidx >= flow->npagesets)
                goto ok;

used_list:
        /* Now look at partially used groups */
        list_for_each_entry(used, &rcd->tid_used_list.list, list) {
                use = min_t(u32, flow->npagesets - pageidx,
                            used->size - used->used);
                kern_add_tid_node(flow, rcd, "used groups", used, use);

                pageidx += use;
                if (pageidx >= flow->npagesets)
                        goto ok;
        }

        /*
         * Look again at a complete group, continuing from where we left.
         * However, if we are at the head, we have reached the end of the
         * complete groups list from the first loop above
         */
        if (group && &group->list == &rcd->tid_group_list.list)
                goto bail_eagain;
        group = list_prepare_entry(group, &rcd->tid_group_list.list,
                                   list);
        if (list_is_last(&group->list, &rcd->tid_group_list.list))
                goto bail_eagain;
        group = list_next_entry(group, list);
        use = min_t(u32, flow->npagesets - pageidx, group->size);
        kern_add_tid_node(flow, rcd, "complete continue", group, use);
        pageidx += use;
        if (pageidx >= flow->npagesets)
                goto ok;
bail_eagain:
        trace_hfi1_msg_alloc_tids(flow->req->qp, " insufficient tids: needed ",
                                  (u64)flow->npagesets);
        return -EAGAIN;
ok:
        return 0;
}

static void kern_program_rcv_group(struct tid_rdma_flow *flow, int grp_num,
                                   u32 *pset_idx)
{
        struct hfi1_ctxtdata *rcd = flow->req->rcd;
        struct hfi1_devdata *dd = rcd->dd;
        struct kern_tid_node *node = &flow->tnode[grp_num];
        struct tid_group *grp = node->grp;
        struct tid_rdma_pageset *pset;
        u32 pmtu_pg = flow->req->qp->pmtu >> PAGE_SHIFT;
        u32 rcventry, npages = 0, pair = 0, tidctrl;
        u8 i, cnt = 0;

        for (i = 0; i < grp->size; i++) {
                rcventry = grp->base + i;

                if (node->map & BIT(i) || cnt >= node->cnt) {
                        rcv_array_wc_fill(dd, rcventry);
                        continue;
                }
                pset = &flow->pagesets[(*pset_idx)++];
                if (pset->count) {
                        hfi1_put_tid(dd, rcventry, PT_EXPECTED,
                                     pset->addr, trdma_pset_order(pset));
                } else {
                        hfi1_put_tid(dd, rcventry, PT_INVALID, 0, 0);
                }
                npages += pset->count;

                rcventry -= rcd->expected_base;
                tidctrl = pair ? 0x3 : rcventry & 0x1 ? 0x2 : 0x1;
                /*
                 * A single TID entry will be used to use a rcvarr pair (with
                 * tidctrl 0x3), if ALL these are true (a) the bit pos is even
                 * (b) the group map shows current and the next bits as free
                 * indicating two consecutive rcvarry entries are available (c)
                 * we actually need 2 more entries
                 */
                pair = !(i & 0x1) && !((node->map >> i) & 0x3) &&
                        node->cnt >= cnt + 2;
                if (!pair) {
                        if (!pset->count)
                                tidctrl = 0x1;
                        flow->tid_entry[flow->tidcnt++] =
                                EXP_TID_SET(IDX, rcventry >> 1) |
                                EXP_TID_SET(CTRL, tidctrl) |
                                EXP_TID_SET(LEN, npages);
                        trace_hfi1_tid_entry_alloc(/* entry */
                           flow->req->qp, flow->tidcnt - 1,
                           flow->tid_entry[flow->tidcnt - 1]);

                        /* Efficient DIV_ROUND_UP(npages, pmtu_pg) */
                        flow->npkts += (npages + pmtu_pg - 1) >> ilog2(pmtu_pg);
                        npages = 0;
                }

                if (grp->used == grp->size - 1)
                        tid_group_move(grp, &rcd->tid_used_list,
                                       &rcd->tid_full_list);
                else if (!grp->used)
                        tid_group_move(grp, &rcd->tid_group_list,
                                       &rcd->tid_used_list);

                grp->used++;
                grp->map |= BIT(i);
                cnt++;
        }
}

static void kern_unprogram_rcv_group(struct tid_rdma_flow *flow, int grp_num)
{
        struct hfi1_ctxtdata *rcd = flow->req->rcd;
        struct hfi1_devdata *dd = rcd->dd;
        struct kern_tid_node *node = &flow->tnode[grp_num];
        struct tid_group *grp = node->grp;
        u32 rcventry;
        u8 i, cnt = 0;

        for (i = 0; i < grp->size; i++) {
                rcventry = grp->base + i;

                if (node->map & BIT(i) || cnt >= node->cnt) {
                        rcv_array_wc_fill(dd, rcventry);
                        continue;
                }

                hfi1_put_tid(dd, rcventry, PT_INVALID, 0, 0);

                grp->used--;
                grp->map &= ~BIT(i);
                cnt++;

                if (grp->used == grp->size - 1)
                        tid_group_move(grp, &rcd->tid_full_list,
                                       &rcd->tid_used_list);
                else if (!grp->used)
                        tid_group_move(grp, &rcd->tid_used_list,
                                       &rcd->tid_group_list);
        }
        if (WARN_ON_ONCE(cnt & 1)) {
                struct hfi1_ctxtdata *rcd = flow->req->rcd;
                struct hfi1_devdata *dd = rcd->dd;

                dd_dev_err(dd, "unexpected odd free cnt %u map 0x%x used %u",
                           cnt, grp->map, grp->used);
        }
}

static void kern_program_rcvarray(struct tid_rdma_flow *flow)
{
        u32 pset_idx = 0;
        int i;

        flow->npkts = 0;
        flow->tidcnt = 0;
        for (i = 0; i < flow->tnode_cnt; i++)
                kern_program_rcv_group(flow, i, &pset_idx);
        trace_hfi1_tid_flow_alloc(flow->req->qp, flow->req->setup_head, flow);
}

/**
 * hfi1_kern_exp_rcv_setup() - setup TID's and flow for one segment of a
 * TID RDMA request
 *
 * @req: TID RDMA request for which the segment/flow is being set up
 * @ss: sge state, maintains state across successive segments of a sge
 * @last: set to true after the last sge segment has been processed
 *
 * This function
 * (1) finds a free flow entry in the flow circular buffer
 * (2) finds pages and continuous physical chunks constituing one segment
 *     of an sge
 * (3) allocates TID group entries for those chunks
 * (4) programs rcvarray entries in the hardware corresponding to those
 *     TID's
 * (5) computes a tidarray with formatted TID entries which can be sent
 *     to the sender
 * (6) Reserves and programs HW flows.
 * (7) It also manages queueing the QP when TID/flow resources are not
 *     available.
 *
 * @req points to struct tid_rdma_request of which the segments are a part. The
 * function uses qp, rcd and seg_len members of @req. In the absence of errors,
 * req->flow_idx is the index of the flow which has been prepared in this
 * invocation of function call. With flow = &req->flows[req->flow_idx],
 * flow->tid_entry contains the TID array which the sender can use for TID RDMA
 * sends and flow->npkts contains number of packets required to send the
 * segment.
 *
 * hfi1_check_sge_align should be called prior to calling this function and if
 * it signals error TID RDMA cannot be used for this sge and this function
 * should not be called.
 *
 * For the queuing, caller must hold the flow->req->qp s_lock from the send
 * engine and the function will procure the exp_lock.
 *
 * Return:
 * The function returns -EAGAIN if sufficient number of TID/flow resources to
 * map the segment could not be allocated. In this case the function should be
 * called again with previous arguments to retry the TID allocation. There are
 * no other error returns. The function returns 0 on success.
 */
int hfi1_kern_exp_rcv_setup(struct tid_rdma_request *req,
                            struct rvt_sge_state *ss, bool *last)
        __must_hold(&req->qp->s_lock)
{
        struct tid_rdma_flow *flow = &req->flows[req->setup_head];
        struct hfi1_ctxtdata *rcd = req->rcd;
        struct hfi1_qp_priv *qpriv = req->qp->priv;
        unsigned long flags;
        struct rvt_qp *fqp;
        u16 clear_tail = req->clear_tail;

        lockdep_assert_held(&req->qp->s_lock);
        /*
         * We return error if either (a) we don't have space in the flow
         * circular buffer, or (b) we already have max entries in the buffer.
         * Max entries depend on the type of request we are processing and the
         * negotiated TID RDMA parameters.
         */
        if (!CIRC_SPACE(req->setup_head, clear_tail, MAX_FLOWS) ||
            CIRC_CNT(req->setup_head, clear_tail, MAX_FLOWS) >=
            req->n_flows)
                return -EINVAL;

        /*
         * Get pages, identify contiguous physical memory chunks for the segment
         * If we can not determine a DMA address mapping we will treat it just
         * like if we ran out of space above.
         */
        if (kern_get_phys_blocks(flow, qpriv->pages, ss, last)) {
                hfi1_wait_kmem(flow->req->qp);
                return -ENOMEM;
        }

        spin_lock_irqsave(&rcd->exp_lock, flags);
        if (kernel_tid_waiters(rcd, &rcd->rarr_queue, flow->req->qp))
                goto queue;

        /*
         * At this point we know the number of pagesets and hence the number of
         * TID's to map the segment. Allocate the TID's from the TID groups. If
         * we cannot allocate the required number we exit and try again later
         */
        if (kern_alloc_tids(flow))
                goto queue;
        /*
         * Finally program the TID entries with the pagesets, compute the
         * tidarray and enable the HW flow
         */
        kern_program_rcvarray(flow);

        /*
         * Setup the flow state with relevant information.
         * This information is used for tracking the sequence of data packets
         * for the segment.
         * The flow is setup here as this is the most accurate time and place
         * to do so. Doing at a later time runs the risk of the flow data in
         * qpriv getting out of sync.
         */
        memset(&flow->flow_state, 0x0, sizeof(flow->flow_state));
        flow->idx = qpriv->flow_state.index;
        flow->flow_state.generation = qpriv->flow_state.generation;
        flow->flow_state.spsn = qpriv->flow_state.psn;
        flow->flow_state.lpsn = flow->flow_state.spsn + flow->npkts - 1;
        flow->flow_state.r_next_psn =
                full_flow_psn(flow, flow->flow_state.spsn);
        qpriv->flow_state.psn += flow->npkts;

        dequeue_tid_waiter(rcd, &rcd->rarr_queue, flow->req->qp);
        /* get head before dropping lock */
        fqp = first_qp(rcd, &rcd->rarr_queue);
        spin_unlock_irqrestore(&rcd->exp_lock, flags);
        tid_rdma_schedule_tid_wakeup(fqp);

        req->setup_head = (req->setup_head + 1) & (MAX_FLOWS - 1);
        return 0;
queue:
        queue_qp_for_tid_wait(rcd, &rcd->rarr_queue, flow->req->qp);
        spin_unlock_irqrestore(&rcd->exp_lock, flags);
        return -EAGAIN;
}

static void hfi1_tid_rdma_reset_flow(struct tid_rdma_flow *flow)
{
        flow->npagesets = 0;
}

/*
 * This function is called after one segment has been successfully sent to
 * release the flow and TID HW/SW resources for that segment. The segments for a
 * TID RDMA request are setup and cleared in FIFO order which is managed using a
 * circular buffer.
 */
int hfi1_kern_exp_rcv_clear(struct tid_rdma_request *req)
        __must_hold(&req->qp->s_lock)
{
        struct tid_rdma_flow *flow = &req->flows[req->clear_tail];
        struct hfi1_ctxtdata *rcd = req->rcd;
        unsigned long flags;
        int i;
        struct rvt_qp *fqp;

        lockdep_assert_held(&req->qp->s_lock);
        /* Exit if we have nothing in the flow circular buffer */
        if (!CIRC_CNT(req->setup_head, req->clear_tail, MAX_FLOWS))
                return -EINVAL;

        spin_lock_irqsave(&rcd->exp_lock, flags);

        for (i = 0; i < flow->tnode_cnt; i++)
                kern_unprogram_rcv_group(flow, i);
        /* To prevent double unprogramming */
        flow->tnode_cnt = 0;
        /* get head before dropping lock */
        fqp = first_qp(rcd, &rcd->rarr_queue);
        spin_unlock_irqrestore(&rcd->exp_lock, flags);

        dma_unmap_flow(flow);

        hfi1_tid_rdma_reset_flow(flow);
        req->clear_tail = (req->clear_tail + 1) & (MAX_FLOWS - 1);

        if (fqp == req->qp) {
                __trigger_tid_waiter(fqp);
                rvt_put_qp(fqp);
        } else {
                tid_rdma_schedule_tid_wakeup(fqp);
        }

        return 0;
}

/*
 * This function is called to release all the tid entries for
 * a request.
 */
void hfi1_kern_exp_rcv_clear_all(struct tid_rdma_request *req)
        __must_hold(&req->qp->s_lock)
{
        /* Use memory barrier for proper ordering */
        while (CIRC_CNT(req->setup_head, req->clear_tail, MAX_FLOWS)) {
                if (hfi1_kern_exp_rcv_clear(req))
                        break;
        }
}

/**
 * hfi1_kern_exp_rcv_free_flows - free previously allocated flow information
 * @req: the tid rdma request to be cleaned
 */
static void hfi1_kern_exp_rcv_free_flows(struct tid_rdma_request *req)
{
        kfree(req->flows);
        req->flows = NULL;
}

/**
 * __trdma_clean_swqe - clean up for large sized QPs
 * @qp: the queue patch
 * @wqe: the send wqe
 */
void __trdma_clean_swqe(struct rvt_qp *qp, struct rvt_swqe *wqe)
{
        struct hfi1_swqe_priv *p = wqe->priv;

        hfi1_kern_exp_rcv_free_flows(&p->tid_req);
}

/*
 * This can be called at QP create time or in the data path.
 */
static int hfi1_kern_exp_rcv_alloc_flows(struct tid_rdma_request *req,
                                         gfp_t gfp)
{
        struct tid_rdma_flow *flows;
        int i;

        if (likely(req->flows))
                return 0;
        flows = kmalloc_node(MAX_FLOWS * sizeof(*flows), gfp,
                             req->rcd->numa_id);
        if (!flows)
                return -ENOMEM;
        /* mini init */
        for (i = 0; i < MAX_FLOWS; i++) {
                flows[i].req = req;
                flows[i].npagesets = 0;
                flows[i].pagesets[0].mapped =  0;
                flows[i].resync_npkts = 0;
        }
        req->flows = flows;
        return 0;
}

static void hfi1_init_trdma_req(struct rvt_qp *qp,
                                struct tid_rdma_request *req)
{
        struct hfi1_qp_priv *qpriv = qp->priv;

        /*
         * Initialize various TID RDMA request variables.
         * These variables are "static", which is why they
         * can be pre-initialized here before the WRs has
         * even been submitted.
         * However, non-NULL values for these variables do not
         * imply that this WQE has been enabled for TID RDMA.
         * Drivers should check the WQE's opcode to determine
         * if a request is a TID RDMA one or not.
         */
        req->qp = qp;
        req->rcd = qpriv->rcd;
}

u64 hfi1_access_sw_tid_wait(const struct cntr_entry *entry,
                            void *context, int vl, int mode, u64 data)
{
        struct hfi1_devdata *dd = context;

        return dd->verbs_dev.n_tidwait;
}

static struct tid_rdma_flow *find_flow_ib(struct tid_rdma_request *req,
                                          u32 psn, u16 *fidx)
{
        u16 head, tail;
        struct tid_rdma_flow *flow;

        head = req->setup_head;
        tail = req->clear_tail;
        for ( ; CIRC_CNT(head, tail, MAX_FLOWS);
             tail = CIRC_NEXT(tail, MAX_FLOWS)) {
                flow = &req->flows[tail];
                if (cmp_psn(psn, flow->flow_state.ib_spsn) >= 0 &&
                    cmp_psn(psn, flow->flow_state.ib_lpsn) <= 0) {
                        if (fidx)
                                *fidx = tail;
                        return flow;
                }
        }
        return NULL;
}

/* TID RDMA READ functions */
u32 hfi1_build_tid_rdma_read_packet(struct rvt_swqe *wqe,
                                    struct ib_other_headers *ohdr, u32 *bth1,
                                    u32 *bth2, u32 *len)
{
        struct tid_rdma_request *req = wqe_to_tid_req(wqe);
        struct tid_rdma_flow *flow = &req->flows[req->flow_idx];
        struct rvt_qp *qp = req->qp;
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct hfi1_swqe_priv *wpriv = wqe->priv;
        struct tid_rdma_read_req *rreq = &ohdr->u.tid_rdma.r_req;
        struct tid_rdma_params *remote;
        u32 req_len = 0;
        void *req_addr = NULL;

        /* This is the IB psn used to send the request */
        *bth2 = mask_psn(flow->flow_state.ib_spsn + flow->pkt);
        trace_hfi1_tid_flow_build_read_pkt(qp, req->flow_idx, flow);

        /* TID Entries for TID RDMA READ payload */
        req_addr = &flow->tid_entry[flow->tid_idx];
        req_len = sizeof(*flow->tid_entry) *
                        (flow->tidcnt - flow->tid_idx);

        memset(&ohdr->u.tid_rdma.r_req, 0, sizeof(ohdr->u.tid_rdma.r_req));
        wpriv->ss.sge.vaddr = req_addr;
        wpriv->ss.sge.sge_length = req_len;
        wpriv->ss.sge.length = wpriv->ss.sge.sge_length;
        /*
         * We can safely zero these out. Since the first SGE covers the
         * entire packet, nothing else should even look at the MR.
         */
        wpriv->ss.sge.mr = NULL;
        wpriv->ss.sge.m = 0;
        wpriv->ss.sge.n = 0;

        wpriv->ss.sg_list = NULL;
        wpriv->ss.total_len = wpriv->ss.sge.sge_length;
        wpriv->ss.num_sge = 1;

        /* Construct the TID RDMA READ REQ packet header */
        rcu_read_lock();
        remote = rcu_dereference(qpriv->tid_rdma.remote);

        KDETH_RESET(rreq->kdeth0, KVER, 0x1);
        KDETH_RESET(rreq->kdeth1, JKEY, remote->jkey);
        rreq->reth.vaddr = cpu_to_be64(wqe->rdma_wr.remote_addr +
                           req->cur_seg * req->seg_len + flow->sent);
        rreq->reth.rkey = cpu_to_be32(wqe->rdma_wr.rkey);
        rreq->reth.length = cpu_to_be32(*len);
        rreq->tid_flow_psn =
                cpu_to_be32((flow->flow_state.generation <<
                             HFI1_KDETH_BTH_SEQ_SHIFT) |
                            ((flow->flow_state.spsn + flow->pkt) &
                             HFI1_KDETH_BTH_SEQ_MASK));
        rreq->tid_flow_qp =
                cpu_to_be32(qpriv->tid_rdma.local.qp |
                            ((flow->idx & TID_RDMA_DESTQP_FLOW_MASK) <<
                             TID_RDMA_DESTQP_FLOW_SHIFT) |
                            qpriv->rcd->ctxt);
        rreq->verbs_qp = cpu_to_be32(qp->remote_qpn);
        *bth1 &= ~RVT_QPN_MASK;
        *bth1 |= remote->qp;
        *bth2 |= IB_BTH_REQ_ACK;
        rcu_read_unlock();

        /* We are done with this segment */
        flow->sent += *len;
        req->cur_seg++;
        qp->s_state = TID_OP(READ_REQ);
        req->ack_pending++;
        req->flow_idx = (req->flow_idx + 1) & (MAX_FLOWS - 1);
        qpriv->pending_tid_r_segs++;
        qp->s_num_rd_atomic++;

        /* Set the TID RDMA READ request payload size */
        *len = req_len;

        return sizeof(ohdr->u.tid_rdma.r_req) / sizeof(u32);
}

/*
 * @len: contains the data length to read upon entry and the read request
 *       payload length upon exit.
 */
u32 hfi1_build_tid_rdma_read_req(struct rvt_qp *qp, struct rvt_swqe *wqe,
                                 struct ib_other_headers *ohdr, u32 *bth1,
                                 u32 *bth2, u32 *len)
        __must_hold(&qp->s_lock)
{
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct tid_rdma_request *req = wqe_to_tid_req(wqe);
        struct tid_rdma_flow *flow = NULL;
        u32 hdwords = 0;
        bool last;
        bool retry = true;
        u32 npkts = rvt_div_round_up_mtu(qp, *len);

        trace_hfi1_tid_req_build_read_req(qp, 0, wqe->wr.opcode, wqe->psn,
                                          wqe->lpsn, req);
        /*
         * Check sync conditions. Make sure that there are no pending
         * segments before freeing the flow.
         */
sync_check:
        if (req->state == TID_REQUEST_SYNC) {
                if (qpriv->pending_tid_r_segs)
                        goto done;

                hfi1_kern_clear_hw_flow(req->rcd, qp);
                qpriv->s_flags &= ~HFI1_R_TID_SW_PSN;
                req->state = TID_REQUEST_ACTIVE;
        }

        /*
         * If the request for this segment is resent, the tid resources should
         * have been allocated before. In this case, req->flow_idx should
         * fall behind req->setup_head.
         */
        if (req->flow_idx == req->setup_head) {
                retry = false;
                if (req->state == TID_REQUEST_RESEND) {
                        /*
                         * This is the first new segment for a request whose
                         * earlier segments have been re-sent. We need to
                         * set up the sge pointer correctly.
                         */
                        restart_sge(&qp->s_sge, wqe, req->s_next_psn,
                                    qp->pmtu);
                        req->isge = 0;
                        req->state = TID_REQUEST_ACTIVE;
                }

                /*
                 * Check sync. The last PSN of each generation is reserved for
                 * RESYNC.
                 */
                if ((qpriv->flow_state.psn + npkts) > MAX_TID_FLOW_PSN - 1) {
                        req->state = TID_REQUEST_SYNC;
                        goto sync_check;
                }

                /* Allocate the flow if not yet */
                if (hfi1_kern_setup_hw_flow(qpriv->rcd, qp))
                        goto done;

                /*
                 * The following call will advance req->setup_head after
                 * allocating the tid entries.
                 */
                if (hfi1_kern_exp_rcv_setup(req, &qp->s_sge, &last)) {
                        req->state = TID_REQUEST_QUEUED;

                        /*
                         * We don't have resources for this segment. The QP has
                         * already been queued.
                         */
                        goto done;
                }
        }

        /* req->flow_idx should only be one slot behind req->setup_head */
        flow = &req->flows[req->flow_idx];
        flow->pkt = 0;
        flow->tid_idx = 0;
        flow->sent = 0;
        if (!retry) {
                /* Set the first and last IB PSN for the flow in use.*/
                flow->flow_state.ib_spsn = req->s_next_psn;
                flow->flow_state.ib_lpsn =
                        flow->flow_state.ib_spsn + flow->npkts - 1;
        }

        /* Calculate the next segment start psn.*/
        req->s_next_psn += flow->npkts;

        /* Build the packet header */
        hdwords = hfi1_build_tid_rdma_read_packet(wqe, ohdr, bth1, bth2, len);
done:
        return hdwords;
}

/*
 * Validate and accept the TID RDMA READ request parameters.
 * Return 0 if the request is accepted successfully;
 * Return 1 otherwise.
 */
static int tid_rdma_rcv_read_request(struct rvt_qp *qp,
                                     struct rvt_ack_entry *e,
                                     struct hfi1_packet *packet,
                                     struct ib_other_headers *ohdr,
                                     u32 bth0, u32 psn, u64 vaddr, u32 len)
{
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct tid_rdma_request *req;
        struct tid_rdma_flow *flow;
        u32 flow_psn, i, tidlen = 0, pktlen, tlen;

        req = ack_to_tid_req(e);

        /* Validate the payload first */
        flow = &req->flows[req->setup_head];

        /* payload length = packet length - (header length + ICRC length) */
        pktlen = packet->tlen - (packet->hlen + 4);
        if (pktlen > sizeof(flow->tid_entry))
                return 1;
        memcpy(flow->tid_entry, packet->ebuf, pktlen);
        flow->tidcnt = pktlen / sizeof(*flow->tid_entry);

        /*
         * Walk the TID_ENTRY list to make sure we have enough space for a
         * complete segment. Also calculate the number of required packets.
         */
        flow->npkts = rvt_div_round_up_mtu(qp, len);
        for (i = 0; i < flow->tidcnt; i++) {
                trace_hfi1_tid_entry_rcv_read_req(qp, i,
                                                  flow->tid_entry[i]);
                tlen = EXP_TID_GET(flow->tid_entry[i], LEN);
                if (!tlen)
                        return 1;

                /*
                 * For tid pair (tidctr == 3), the buffer size of the pair
                 * should be the sum of the buffer size described by each
                 * tid entry. However, only the first entry needs to be
                 * specified in the request (see WFR HAS Section 8.5.7.1).
                 */
                tidlen += tlen;
        }
        if (tidlen * PAGE_SIZE < len)
                return 1;

        /* Empty the flow array */
        req->clear_tail = req->setup_head;
        flow->pkt = 0;
        flow->tid_idx = 0;
        flow->tid_offset = 0;
        flow->sent = 0;
        flow->tid_qpn = be32_to_cpu(ohdr->u.tid_rdma.r_req.tid_flow_qp);
        flow->idx = (flow->tid_qpn >> TID_RDMA_DESTQP_FLOW_SHIFT) &
                    TID_RDMA_DESTQP_FLOW_MASK;
        flow_psn = mask_psn(be32_to_cpu(ohdr->u.tid_rdma.r_req.tid_flow_psn));
        flow->flow_state.generation = flow_psn >> HFI1_KDETH_BTH_SEQ_SHIFT;
        flow->flow_state.spsn = flow_psn & HFI1_KDETH_BTH_SEQ_MASK;
        flow->length = len;

        flow->flow_state.lpsn = flow->flow_state.spsn +
                flow->npkts - 1;
        flow->flow_state.ib_spsn = psn;
        flow->flow_state.ib_lpsn = flow->flow_state.ib_spsn + flow->npkts - 1;

        trace_hfi1_tid_flow_rcv_read_req(qp, req->setup_head, flow);
        /* Set the initial flow index to the current flow. */
        req->flow_idx = req->setup_head;

        /* advance circular buffer head */
        req->setup_head = (req->setup_head + 1) & (MAX_FLOWS - 1);

        /*
         * Compute last PSN for request.
         */
        e->opcode = (bth0 >> 24) & 0xff;
        e->psn = psn;
        e->lpsn = psn + flow->npkts - 1;
        e->sent = 0;

        req->n_flows = qpriv->tid_rdma.local.max_read;
        req->state = TID_REQUEST_ACTIVE;
        req->cur_seg = 0;
        req->comp_seg = 0;
        req->ack_seg = 0;
        req->isge = 0;
        req->seg_len = qpriv->tid_rdma.local.max_len;
        req->total_len = len;
        req->total_segs = 1;
        req->r_flow_psn = e->psn;

        trace_hfi1_tid_req_rcv_read_req(qp, 0, e->opcode, e->psn, e->lpsn,
                                        req);
        return 0;
}

static int tid_rdma_rcv_error(struct hfi1_packet *packet,
                              struct ib_other_headers *ohdr,
                              struct rvt_qp *qp, u32 psn, int diff)
{
        struct hfi1_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
        struct hfi1_ctxtdata *rcd = ((struct hfi1_qp_priv *)qp->priv)->rcd;
        struct hfi1_ibdev *dev = to_idev(qp->ibqp.device);
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct rvt_ack_entry *e;
        struct tid_rdma_request *req;
        unsigned long flags;
        u8 prev;
        bool old_req;

        trace_hfi1_rsp_tid_rcv_error(qp, psn);
        trace_hfi1_tid_rdma_rcv_err(qp, 0, psn, diff);
        if (diff > 0) {
                /* sequence error */
                if (!qp->r_nak_state) {
                        ibp->rvp.n_rc_seqnak++;
                        qp->r_nak_state = IB_NAK_PSN_ERROR;
                        qp->r_ack_psn = qp->r_psn;
                        rc_defered_ack(rcd, qp);
                }
                goto done;
        }

        ibp->rvp.n_rc_dupreq++;

        spin_lock_irqsave(&qp->s_lock, flags);
        e = find_prev_entry(qp, psn, &prev, NULL, &old_req);
        if (!e || (e->opcode != TID_OP(READ_REQ) &&
                   e->opcode != TID_OP(WRITE_REQ)))
                goto unlock;

        req = ack_to_tid_req(e);
        req->r_flow_psn = psn;
        trace_hfi1_tid_req_rcv_err(qp, 0, e->opcode, e->psn, e->lpsn, req);
        if (e->opcode == TID_OP(READ_REQ)) {
                struct ib_reth *reth;
                u32 len;
                u32 rkey;
                u64 vaddr;
                int ok;
                u32 bth0;

                reth = &ohdr->u.tid_rdma.r_req.reth;
                /*
                 * The requester always restarts from the start of the original
                 * request.
                 */
                len = be32_to_cpu(reth->length);
                if (psn != e->psn || len != req->total_len)
                        goto unlock;

                release_rdma_sge_mr(e);

                rkey = be32_to_cpu(reth->rkey);
                vaddr = get_ib_reth_vaddr(reth);

                qp->r_len = len;
                ok = rvt_rkey_ok(qp, &e->rdma_sge, len, vaddr, rkey,
                                 IB_ACCESS_REMOTE_READ);
                if (unlikely(!ok))
                        goto unlock;

                /*
                 * If all the response packets for the current request have
                 * been sent out and this request is complete (old_request
                 * == false) and the TID flow may be unusable (the
                 * req->clear_tail is advanced). However, when an earlier
                 * request is received, this request will not be complete any
                 * more (qp->s_tail_ack_queue is moved back, see below).
                 * Consequently, we need to update the TID flow info every time
                 * a duplicate request is received.
                 */
                bth0 = be32_to_cpu(ohdr->bth[0]);
                if (tid_rdma_rcv_read_request(qp, e, packet, ohdr, bth0, psn,
                                              vaddr, len))
                        goto unlock;

                /*
                 * True if the request is already scheduled (between
                 * qp->s_tail_ack_queue and qp->r_head_ack_queue);
                 */
                if (old_req)
                        goto unlock;
        } else {
                struct flow_state *fstate;
                bool schedule = false;
                u8 i;

                if (req->state == TID_REQUEST_RESEND) {
                        req->state = TID_REQUEST_RESEND_ACTIVE;
                } else if (req->state == TID_REQUEST_INIT_RESEND) {
                        req->state = TID_REQUEST_INIT;
                        schedule = true;
                }

                /*
                 * True if the request is already scheduled (between
                 * qp->s_tail_ack_queue and qp->r_head_ack_queue).
                 * Also, don't change requests, which are at the SYNC
                 * point and haven't generated any responses yet.
                 * There is nothing to retransmit for them yet.
                 */
                if (old_req || req->state == TID_REQUEST_INIT ||
                    (req->state == TID_REQUEST_SYNC && !req->cur_seg)) {
                        for (i = prev + 1; ; i++) {
                                if (i > rvt_size_atomic(&dev->rdi))
                                        i = 0;
                                if (i == qp->r_head_ack_queue)
                                        break;
                                e = &qp->s_ack_queue[i];
                                req = ack_to_tid_req(e);
                                if (e->opcode == TID_OP(WRITE_REQ) &&
                                    req->state == TID_REQUEST_INIT)
                                        req->state = TID_REQUEST_INIT_RESEND;
                        }
                        /*
                         * If the state of the request has been changed,
                         * the first leg needs to get scheduled in order to
                         * pick up the change. Otherwise, normal response
                         * processing should take care of it.
                         */
                        if (!schedule)
                                goto unlock;
                }

                /*
                 * If there is no more allocated segment, just schedule the qp
                 * without changing any state.
                 */
                if (req->clear_tail == req->setup_head)
                        goto schedule;
                /*
                 * If this request has sent responses for segments, which have
                 * not received data yet (flow_idx != clear_tail), the flow_idx
                 * pointer needs to be adjusted so the same responses can be
                 * re-sent.
                 */
                if (CIRC_CNT(req->flow_idx, req->clear_tail, MAX_FLOWS)) {
                        fstate = &req->flows[req->clear_tail].flow_state;
                        qpriv->pending_tid_w_segs -=
                                CIRC_CNT(req->flow_idx, req->clear_tail,
                                         MAX_FLOWS);
                        req->flow_idx =
                                CIRC_ADD(req->clear_tail,
                                         delta_psn(psn, fstate->resp_ib_psn),
                                         MAX_FLOWS);
                        qpriv->pending_tid_w_segs +=
                                delta_psn(psn, fstate->resp_ib_psn);
                        /*
                         * When flow_idx == setup_head, we've gotten a duplicate
                         * request for a segment, which has not been allocated
                         * yet. In that case, don't adjust this request.
                         * However, we still want to go through the loop below
                         * to adjust all subsequent requests.
                         */
                        if (CIRC_CNT(req->setup_head, req->flow_idx,
                                     MAX_FLOWS)) {
                                req->cur_seg = delta_psn(psn, e->psn);
                                req->state = TID_REQUEST_RESEND_ACTIVE;
                        }
                }

                for (i = prev + 1; ; i++) {
                        /*
                         * Look at everything up to and including
                         * s_tail_ack_queue
                         */
                        if (i > rvt_size_atomic(&dev->rdi))
                                i = 0;
                        if (i == qp->r_head_ack_queue)
                                break;
                        e = &qp->s_ack_queue[i];
                        req = ack_to_tid_req(e);
                        trace_hfi1_tid_req_rcv_err(qp, 0, e->opcode, e->psn,
                                                   e->lpsn, req);
                        if (e->opcode != TID_OP(WRITE_REQ) ||
                            req->cur_seg == req->comp_seg ||
                            req->state == TID_REQUEST_INIT ||
                            req->state == TID_REQUEST_INIT_RESEND) {
                                if (req->state == TID_REQUEST_INIT)
                                        req->state = TID_REQUEST_INIT_RESEND;
                                continue;
                        }
                        qpriv->pending_tid_w_segs -=
                                CIRC_CNT(req->flow_idx,
                                         req->clear_tail,
                                         MAX_FLOWS);
                        req->flow_idx = req->clear_tail;
                        req->state = TID_REQUEST_RESEND;
                        req->cur_seg = req->comp_seg;
                }
                qpriv->s_flags &= ~HFI1_R_TID_WAIT_INTERLCK;
        }
        /* Re-process old requests.*/
        if (qp->s_acked_ack_queue == qp->s_tail_ack_queue)
                qp->s_acked_ack_queue = prev;
        qp->s_tail_ack_queue = prev;
        /*
         * Since the qp->s_tail_ack_queue is modified, the
         * qp->s_ack_state must be changed to re-initialize
         * qp->s_ack_rdma_sge; Otherwise, we will end up in
         * wrong memory region.
         */
        qp->s_ack_state = OP(ACKNOWLEDGE);
schedule:
        /*
         * It's possible to receive a retry psn that is earlier than an RNRNAK
         * psn. In this case, the rnrnak state should be cleared.
         */
        if (qpriv->rnr_nak_state) {
                qp->s_nak_state = 0;
                qpriv->rnr_nak_state = TID_RNR_NAK_INIT;
                qp->r_psn = e->lpsn + 1;
                hfi1_tid_write_alloc_resources(qp, true);
        }

        qp->r_state = e->opcode;
        qp->r_nak_state = 0;
        qp->s_flags |= RVT_S_RESP_PENDING;
        hfi1_schedule_send(qp);
unlock:
        spin_unlock_irqrestore(&qp->s_lock, flags);
done:
        return 1;
}

void hfi1_rc_rcv_tid_rdma_read_req(struct hfi1_packet *packet)
{
        /* HANDLER FOR TID RDMA READ REQUEST packet (Responder side)*/

        /*
         * 1. Verify TID RDMA READ REQ as per IB_OPCODE_RC_RDMA_READ
         *    (see hfi1_rc_rcv())
         * 2. Put TID RDMA READ REQ into the response queue (s_ack_queue)
         *     - Setup struct tid_rdma_req with request info
         *     - Initialize struct tid_rdma_flow info;
         *     - Copy TID entries;
         * 3. Set the qp->s_ack_state.
         * 4. Set RVT_S_RESP_PENDING in s_flags.
         * 5. Kick the send engine (hfi1_schedule_send())
         */
        struct hfi1_ctxtdata *rcd = packet->rcd;
        struct rvt_qp *qp = packet->qp;
        struct hfi1_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
        struct ib_other_headers *ohdr = packet->ohdr;
        struct rvt_ack_entry *e;
        unsigned long flags;
        struct ib_reth *reth;
        struct hfi1_qp_priv *qpriv = qp->priv;
        u32 bth0, psn, len, rkey;
        bool fecn;
        u8 next;
        u64 vaddr;
        int diff;
        u8 nack_state = IB_NAK_INVALID_REQUEST;

        bth0 = be32_to_cpu(ohdr->bth[0]);
        if (hfi1_ruc_check_hdr(ibp, packet))
                return;

        fecn = process_ecn(qp, packet);
        psn = mask_psn(be32_to_cpu(ohdr->bth[2]));
        trace_hfi1_rsp_rcv_tid_read_req(qp, psn);

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

        if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_READ)))
                goto nack_inv;

        reth = &ohdr->u.tid_rdma.r_req.reth;
        vaddr = be64_to_cpu(reth->vaddr);
        len = be32_to_cpu(reth->length);
        /* The length needs to be in multiples of PAGE_SIZE */
        if (!len || len & ~PAGE_MASK || len > qpriv->tid_rdma.local.max_len)
                goto nack_inv;

        diff = delta_psn(psn, qp->r_psn);
        if (unlikely(diff)) {
                tid_rdma_rcv_err(packet, ohdr, qp, psn, diff, fecn);
                return;
        }

        /* We've verified the request, insert it into the ack queue. */
        next = qp->r_head_ack_queue + 1;
        if (next > rvt_size_atomic(ib_to_rvt(qp->ibqp.device)))
                next = 0;
        spin_lock_irqsave(&qp->s_lock, flags);
        if (unlikely(next == qp->s_tail_ack_queue)) {
                if (!qp->s_ack_queue[next].sent) {
                        nack_state = IB_NAK_REMOTE_OPERATIONAL_ERROR;
                        goto nack_inv_unlock;
                }
                update_ack_queue(qp, next);
        }
        e = &qp->s_ack_queue[qp->r_head_ack_queue];
        release_rdma_sge_mr(e);

        rkey = be32_to_cpu(reth->rkey);
        qp->r_len = len;

        if (unlikely(!rvt_rkey_ok(qp, &e->rdma_sge, qp->r_len, vaddr,
                                  rkey, IB_ACCESS_REMOTE_READ)))
                goto nack_acc;

        /* Accept the request parameters */
        if (tid_rdma_rcv_read_request(qp, e, packet, ohdr, bth0, psn, vaddr,
                                      len))
                goto nack_inv_unlock;

        qp->r_state = e->opcode;
        qp->r_nak_state = 0;
        /*
         * We need to increment the MSN here instead of when we
         * finish sending the result since a duplicate request would
         * increment it more than once.
         */
        qp->r_msn++;
        qp->r_psn += e->lpsn - e->psn + 1;

        qp->r_head_ack_queue = next;

        /*
         * For all requests other than TID WRITE which are added to the ack
         * queue, qpriv->r_tid_alloc follows qp->r_head_ack_queue. It is ok to
         * do this because of interlocks between these and TID WRITE
         * requests. The same change has also been made in hfi1_rc_rcv().
         */
        qpriv->r_tid_alloc = qp->r_head_ack_queue;

        /* Schedule the send tasklet. */
        qp->s_flags |= RVT_S_RESP_PENDING;
        if (fecn)
                qp->s_flags |= RVT_S_ECN;
        hfi1_schedule_send(qp);

        spin_unlock_irqrestore(&qp->s_lock, flags);
        return;

nack_inv_unlock:
        spin_unlock_irqrestore(&qp->s_lock, flags);
nack_inv:
        rvt_rc_error(qp, IB_WC_LOC_QP_OP_ERR);
        qp->r_nak_state = nack_state;
        qp->r_ack_psn = qp->r_psn;
        /* Queue NAK for later */
        rc_defered_ack(rcd, qp);
        return;
nack_acc:
        spin_unlock_irqrestore(&qp->s_lock, flags);
        rvt_rc_error(qp, IB_WC_LOC_PROT_ERR);
        qp->r_nak_state = IB_NAK_REMOTE_ACCESS_ERROR;
        qp->r_ack_psn = qp->r_psn;
}

u32 hfi1_build_tid_rdma_read_resp(struct rvt_qp *qp, struct rvt_ack_entry *e,
                                  struct ib_other_headers *ohdr, u32 *bth0,
                                  u32 *bth1, u32 *bth2, u32 *len, bool *last)
{
        struct hfi1_ack_priv *epriv = e->priv;
        struct tid_rdma_request *req = &epriv->tid_req;
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct tid_rdma_flow *flow = &req->flows[req->clear_tail];
        u32 tidentry = flow->tid_entry[flow->tid_idx];
        u32 tidlen = EXP_TID_GET(tidentry, LEN) << PAGE_SHIFT;
        struct tid_rdma_read_resp *resp = &ohdr->u.tid_rdma.r_rsp;
        u32 next_offset, om = KDETH_OM_LARGE;
        bool last_pkt;
        u32 hdwords = 0;
        struct tid_rdma_params *remote;

        *len = min_t(u32, qp->pmtu, tidlen - flow->tid_offset);
        flow->sent += *len;
        next_offset = flow->tid_offset + *len;
        last_pkt = (flow->sent >= flow->length);

        trace_hfi1_tid_entry_build_read_resp(qp, flow->tid_idx, tidentry);
        trace_hfi1_tid_flow_build_read_resp(qp, req->clear_tail, flow);

        rcu_read_lock();
        remote = rcu_dereference(qpriv->tid_rdma.remote);
        if (!remote) {
                rcu_read_unlock();
                goto done;
        }
        KDETH_RESET(resp->kdeth0, KVER, 0x1);
        KDETH_SET(resp->kdeth0, SH, !last_pkt);
        KDETH_SET(resp->kdeth0, INTR, !!(!last_pkt && remote->urg));
        KDETH_SET(resp->kdeth0, TIDCTRL, EXP_TID_GET(tidentry, CTRL));
        KDETH_SET(resp->kdeth0, TID, EXP_TID_GET(tidentry, IDX));
        KDETH_SET(resp->kdeth0, OM, om == KDETH_OM_LARGE);
        KDETH_SET(resp->kdeth0, OFFSET, flow->tid_offset / om);
        KDETH_RESET(resp->kdeth1, JKEY, remote->jkey);
        resp->verbs_qp = cpu_to_be32(qp->remote_qpn);
        rcu_read_unlock();

        resp->aeth = rvt_compute_aeth(qp);
        resp->verbs_psn = cpu_to_be32(mask_psn(flow->flow_state.ib_spsn +
                                               flow->pkt));

        *bth0 = TID_OP(READ_RESP) << 24;
        *bth1 = flow->tid_qpn;
        *bth2 = mask_psn(((flow->flow_state.spsn + flow->pkt++) &
                          HFI1_KDETH_BTH_SEQ_MASK) |
                         (flow->flow_state.generation <<
                          HFI1_KDETH_BTH_SEQ_SHIFT));
        *last = last_pkt;
        if (last_pkt)
                /* Advance to next flow */
                req->clear_tail = (req->clear_tail + 1) &
                                  (MAX_FLOWS - 1);

        if (next_offset >= tidlen) {
                flow->tid_offset = 0;
                flow->tid_idx++;
        } else {
                flow->tid_offset = next_offset;
        }

        hdwords = sizeof(ohdr->u.tid_rdma.r_rsp) / sizeof(u32);

done:
        return hdwords;
}

static inline struct tid_rdma_request *
find_tid_request(struct rvt_qp *qp, u32 psn, enum ib_wr_opcode opcode)
        __must_hold(&qp->s_lock)
{
        struct rvt_swqe *wqe;
        struct tid_rdma_request *req = NULL;
        u32 i, end;

        end = qp->s_cur + 1;
        if (end == qp->s_size)
                end = 0;
        for (i = qp->s_acked; i != end;) {
                wqe = rvt_get_swqe_ptr(qp, i);
                if (cmp_psn(psn, wqe->psn) >= 0 &&
                    cmp_psn(psn, wqe->lpsn) <= 0) {
                        if (wqe->wr.opcode == opcode)
                                req = wqe_to_tid_req(wqe);
                        break;
                }
                if (++i == qp->s_size)
                        i = 0;
        }

        return req;
}

void hfi1_rc_rcv_tid_rdma_read_resp(struct hfi1_packet *packet)
{
        /* HANDLER FOR TID RDMA READ RESPONSE packet (Requester side) */

        /*
         * 1. Find matching SWQE
         * 2. Check that the entire segment has been read.
         * 3. Remove HFI1_S_WAIT_TID_RESP from s_flags.
         * 4. Free the TID flow resources.
         * 5. Kick the send engine (hfi1_schedule_send())
         */
        struct ib_other_headers *ohdr = packet->ohdr;
        struct rvt_qp *qp = packet->qp;
        struct hfi1_qp_priv *priv = qp->priv;
        struct hfi1_ctxtdata *rcd = packet->rcd;
        struct tid_rdma_request *req;
        struct tid_rdma_flow *flow;
        u32 opcode, aeth;
        bool fecn;
        unsigned long flags;
        u32 kpsn, ipsn;

        trace_hfi1_sender_rcv_tid_read_resp(qp);
        fecn = process_ecn(qp, packet);
        kpsn = mask_psn(be32_to_cpu(ohdr->bth[2]));
        aeth = be32_to_cpu(ohdr->u.tid_rdma.r_rsp.aeth);
        opcode = (be32_to_cpu(ohdr->bth[0]) >> 24) & 0xff;

        spin_lock_irqsave(&qp->s_lock, flags);
        ipsn = mask_psn(be32_to_cpu(ohdr->u.tid_rdma.r_rsp.verbs_psn));
        req = find_tid_request(qp, ipsn, IB_WR_TID_RDMA_READ);
        if (unlikely(!req))
                goto ack_op_err;

        flow = &req->flows[req->clear_tail];
        /* When header suppression is disabled */
        if (cmp_psn(ipsn, flow->flow_state.ib_lpsn)) {
                update_r_next_psn_fecn(packet, priv, rcd, flow, fecn);

                if (cmp_psn(kpsn, flow->flow_state.r_next_psn))
                        goto ack_done;
                flow->flow_state.r_next_psn = mask_psn(kpsn + 1);
                /*
                 * Copy the payload to destination buffer if this packet is
                 * delivered as an eager packet due to RSM rule and FECN.
                 * The RSM rule selects FECN bit in BTH and SH bit in
                 * KDETH header and therefore will not match the last
                 * packet of each segment that has SH bit cleared.
                 */
                if (fecn && packet->etype == RHF_RCV_TYPE_EAGER) {
                        struct rvt_sge_state ss;
                        u32 len;
                        u32 tlen = packet->tlen;
                        u16 hdrsize = packet->hlen;
                        u8 pad = packet->pad;
                        u8 extra_bytes = pad + packet->extra_byte +
                                (SIZE_OF_CRC << 2);
                        u32 pmtu = qp->pmtu;

                        if (unlikely(tlen != (hdrsize + pmtu + extra_bytes)))
                                goto ack_op_err;
                        len = restart_sge(&ss, req->e.swqe, ipsn, pmtu);
                        if (unlikely(len < pmtu))
                                goto ack_op_err;
                        rvt_copy_sge(qp, &ss, packet->payload, pmtu, false,
                                     false);
                        /* Raise the sw sequence check flag for next packet */
                        priv->s_flags |= HFI1_R_TID_SW_PSN;
                }

                goto ack_done;
        }
        flow->flow_state.r_next_psn = mask_psn(kpsn + 1);
        req->ack_pending--;
        priv->pending_tid_r_segs--;
        qp->s_num_rd_atomic--;
        if ((qp->s_flags & RVT_S_WAIT_FENCE) &&
            !qp->s_num_rd_atomic) {
                qp->s_flags &= ~(RVT_S_WAIT_FENCE |
                                 RVT_S_WAIT_ACK);
                hfi1_schedule_send(qp);
        }
        if (qp->s_flags & RVT_S_WAIT_RDMAR) {
                qp->s_flags &= ~(RVT_S_WAIT_RDMAR | RVT_S_WAIT_ACK);
                hfi1_schedule_send(qp);
        }

        trace_hfi1_ack(qp, ipsn);
        trace_hfi1_tid_req_rcv_read_resp(qp, 0, req->e.swqe->wr.opcode,
                                         req->e.swqe->psn, req->e.swqe->lpsn,
                                         req);
        trace_hfi1_tid_flow_rcv_read_resp(qp, req->clear_tail, flow);

        /* Release the tid resources */
        hfi1_kern_exp_rcv_clear(req);

        if (!do_rc_ack(qp, aeth, ipsn, opcode, 0, rcd))
                goto ack_done;

        /* If not done yet, build next read request */
        if (++req->comp_seg >= req->total_segs) {
                priv->tid_r_comp++;
                req->state = TID_REQUEST_COMPLETE;
        }

        /*
         * Clear the hw flow under two conditions:
         * 1. This request is a sync point and it is complete;
         * 2. Current request is completed and there are no more requests.
         */
        if ((req->state == TID_REQUEST_SYNC &&
             req->comp_seg == req->cur_seg) ||
            priv->tid_r_comp == priv->tid_r_reqs) {
                hfi1_kern_clear_hw_flow(priv->rcd, qp);
                priv->s_flags &= ~HFI1_R_TID_SW_PSN;
                if (req->state == TID_REQUEST_SYNC)
                        req->state = TID_REQUEST_ACTIVE;
        }

        hfi1_schedule_send(qp);
        goto ack_done;

ack_op_err:
        /*
         * The test indicates that the send engine has finished its cleanup
         * after sending the request and it's now safe to put the QP into error
         * state. However, if the wqe queue is empty (qp->s_acked == qp->s_tail
         * == qp->s_head), it would be unsafe to complete the wqe pointed by
         * qp->s_acked here. Putting the qp into error state will safely flush
         * all remaining requests.
         */
        if (qp->s_last == qp->s_acked)
                rvt_error_qp(qp, IB_WC_WR_FLUSH_ERR);

ack_done:
        spin_unlock_irqrestore(&qp->s_lock, flags);
}

void hfi1_kern_read_tid_flow_free(struct rvt_qp *qp)
        __must_hold(&qp->s_lock)
{
        u32 n = qp->s_acked;
        struct rvt_swqe *wqe;
        struct tid_rdma_request *req;
        struct hfi1_qp_priv *priv = qp->priv;

        lockdep_assert_held(&qp->s_lock);
        /* Free any TID entries */
        while (n != qp->s_tail) {
                wqe = rvt_get_swqe_ptr(qp, n);
                if (wqe->wr.opcode == IB_WR_TID_RDMA_READ) {
                        req = wqe_to_tid_req(wqe);
                        hfi1_kern_exp_rcv_clear_all(req);
                }

                if (++n == qp->s_size)
                        n = 0;
        }
        /* Free flow */
        hfi1_kern_clear_hw_flow(priv->rcd, qp);
}

static bool tid_rdma_tid_err(struct hfi1_packet *packet, u8 rcv_type)
{
        struct rvt_qp *qp = packet->qp;

        if (rcv_type >= RHF_RCV_TYPE_IB)
                goto done;

        spin_lock(&qp->s_lock);

        /*
         * We've ran out of space in the eager buffer.
         * Eagerly received KDETH packets which require space in the
         * Eager buffer (packet that have payload) are TID RDMA WRITE
         * response packets. In this case, we have to re-transmit the
         * TID RDMA WRITE request.
         */
        if (rcv_type == RHF_RCV_TYPE_EAGER) {
                hfi1_restart_rc(qp, qp->s_last_psn + 1, 1);
                hfi1_schedule_send(qp);
        }

        /* Since no payload is delivered, just drop the packet */
        spin_unlock(&qp->s_lock);
done:
        return true;
}

static void restart_tid_rdma_read_req(struct hfi1_ctxtdata *rcd,
                                      struct rvt_qp *qp, struct rvt_swqe *wqe)
{
        struct tid_rdma_request *req;
        struct tid_rdma_flow *flow;

        /* Start from the right segment */
        qp->r_flags |= RVT_R_RDMAR_SEQ;
        req = wqe_to_tid_req(wqe);
        flow = &req->flows[req->clear_tail];
        hfi1_restart_rc(qp, flow->flow_state.ib_spsn, 0);
        if (list_empty(&qp->rspwait)) {
                qp->r_flags |= RVT_R_RSP_SEND;
                rvt_get_qp(qp);
                list_add_tail(&qp->rspwait, &rcd->qp_wait_list);
        }
}

/*
 * Handle the KDETH eflags for TID RDMA READ response.
 *
 * Return true if the last packet for a segment has been received and it is
 * time to process the response normally; otherwise, return true.
 *
 * The caller must hold the packet->qp->r_lock and the rcu_read_lock.
 */
static bool handle_read_kdeth_eflags(struct hfi1_ctxtdata *rcd,
                                     struct hfi1_packet *packet, u8 rcv_type,
                                     u8 rte, u32 psn, u32 ibpsn)
        __must_hold(&packet->qp->r_lock) __must_hold(RCU)
{
        struct hfi1_pportdata *ppd = rcd->ppd;
        struct hfi1_devdata *dd = ppd->dd;
        struct hfi1_ibport *ibp;
        struct rvt_swqe *wqe;
        struct tid_rdma_request *req;
        struct tid_rdma_flow *flow;
        u32 ack_psn;
        struct rvt_qp *qp = packet->qp;
        struct hfi1_qp_priv *priv = qp->priv;
        bool ret = true;
        int diff = 0;
        u32 fpsn;

        lockdep_assert_held(&qp->r_lock);
        trace_hfi1_rsp_read_kdeth_eflags(qp, ibpsn);
        trace_hfi1_sender_read_kdeth_eflags(qp);
        trace_hfi1_tid_read_sender_kdeth_eflags(qp, 0);
        spin_lock(&qp->s_lock);
        /* If the psn is out of valid range, drop the packet */
        if (cmp_psn(ibpsn, qp->s_last_psn) < 0 ||
            cmp_psn(ibpsn, qp->s_psn) > 0)
                goto s_unlock;

        /*
         * Note that NAKs implicitly ACK outstanding SEND and RDMA write
         * requests and implicitly NAK RDMA read and atomic requests issued
         * before the NAK'ed request.
         */
        ack_psn = ibpsn - 1;
        wqe = rvt_get_swqe_ptr(qp, qp->s_acked);
        ibp = to_iport(qp->ibqp.device, qp->port_num);

        /* Complete WQEs that the PSN finishes. */
        while ((int)delta_psn(ack_psn, wqe->lpsn) >= 0) {
                /*
                 * If this request is a RDMA read or atomic, and the NACK is
                 * for a later operation, this NACK NAKs the RDMA read or
                 * atomic.
                 */
                if (wqe->wr.opcode == IB_WR_RDMA_READ ||
                    wqe->wr.opcode == IB_WR_TID_RDMA_READ ||
                    wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP ||
                    wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD) {
                        /* Retry this request. */
                        if (!(qp->r_flags & RVT_R_RDMAR_SEQ)) {
                                qp->r_flags |= RVT_R_RDMAR_SEQ;
                                if (wqe->wr.opcode == IB_WR_TID_RDMA_READ) {
                                        restart_tid_rdma_read_req(rcd, qp,
                                                                  wqe);
                                } else {
                                        hfi1_restart_rc(qp, qp->s_last_psn + 1,
                                                        0);
                                        if (list_empty(&qp->rspwait)) {
                                                qp->r_flags |= RVT_R_RSP_SEND;
                                                rvt_get_qp(qp);
                                                list_add_tail(/* wait */
                                                   &qp->rspwait,
                                                   &rcd->qp_wait_list);
                                        }
                                }
                        }
                        /*
                         * No need to process the NAK since we are
                         * restarting an earlier request.
                         */
                        break;
                }

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

        if (qp->s_acked == qp->s_tail)
                goto s_unlock;

        /* Handle the eflags for the request */
        if (wqe->wr.opcode != IB_WR_TID_RDMA_READ)
                goto s_unlock;

        req = wqe_to_tid_req(wqe);
        trace_hfi1_tid_req_read_kdeth_eflags(qp, 0, wqe->wr.opcode, wqe->psn,
                                             wqe->lpsn, req);
        switch (rcv_type) {
        case RHF_RCV_TYPE_EXPECTED:
                switch (rte) {
                case RHF_RTE_EXPECTED_FLOW_SEQ_ERR:
                        /*
                         * On the first occurrence of a Flow Sequence error,
                         * the flag TID_FLOW_SW_PSN is set.
                         *
                         * After that, the flow is *not* reprogrammed and the
                         * protocol falls back to SW PSN checking. This is done
                         * to prevent continuous Flow Sequence errors for any
                         * packets that could be still in the fabric.
                         */
                        flow = &req->flows[req->clear_tail];
                        trace_hfi1_tid_flow_read_kdeth_eflags(qp,
                                                              req->clear_tail,
                                                              flow);
                        if (priv->s_flags & HFI1_R_TID_SW_PSN) {
                                diff = cmp_psn(psn,
                                               flow->flow_state.r_next_psn);
                                if (diff > 0) {
                                        /* Drop the packet.*/
                                        goto s_unlock;
                                } else if (diff < 0) {
                                        /*
                                         * If a response packet for a restarted
                                         * request has come back, reset the
                                         * restart flag.
                                         */
                                        if (qp->r_flags & RVT_R_RDMAR_SEQ)
                                                qp->r_flags &=
                                                        ~RVT_R_RDMAR_SEQ;

                                        /* Drop the packet.*/
                                        goto s_unlock;
                                }

                                /*
                                 * If SW PSN verification is successful and
                                 * this is the last packet in the segment, tell
                                 * the caller to process it as a normal packet.
                                 */
                                fpsn = full_flow_psn(flow,
                                                     flow->flow_state.lpsn);
                                if (cmp_psn(fpsn, psn) == 0) {
                                        ret = false;
                                        if (qp->r_flags & RVT_R_RDMAR_SEQ)
                                                qp->r_flags &=
                                                        ~RVT_R_RDMAR_SEQ;
                                }
                                flow->flow_state.r_next_psn =
                                        mask_psn(psn + 1);
                        } else {
                                u32 last_psn;

                                last_psn = read_r_next_psn(dd, rcd->ctxt,
                                                           flow->idx);
                                flow->flow_state.r_next_psn = last_psn;
                                priv->s_flags |= HFI1_R_TID_SW_PSN;
                                /*
                                 * If no request has been restarted yet,
                                 * restart the current one.
                                 */
                                if (!(qp->r_flags & RVT_R_RDMAR_SEQ))
                                        restart_tid_rdma_read_req(rcd, qp,
                                                                  wqe);
                        }

                        break;

                case RHF_RTE_EXPECTED_FLOW_GEN_ERR:
                        /*
                         * Since the TID flow is able to ride through
                         * generation mismatch, drop this stale packet.
                         */
                        break;

                default:
                        break;
                }
                break;

        case RHF_RCV_TYPE_ERROR:
                switch (rte) {
                case RHF_RTE_ERROR_OP_CODE_ERR:
                case RHF_RTE_ERROR_KHDR_MIN_LEN_ERR:
                case RHF_RTE_ERROR_KHDR_HCRC_ERR:
                case RHF_RTE_ERROR_KHDR_KVER_ERR:
                case RHF_RTE_ERROR_CONTEXT_ERR:
                case RHF_RTE_ERROR_KHDR_TID_ERR:
                default:
                        break;
                }
                break;
        default:
                break;
        }
s_unlock:
        spin_unlock(&qp->s_lock);
        return ret;
}

bool hfi1_handle_kdeth_eflags(struct hfi1_ctxtdata *rcd,
                              struct hfi1_pportdata *ppd,
                              struct hfi1_packet *packet)
{
        struct hfi1_ibport *ibp = &ppd->ibport_data;
        struct hfi1_devdata *dd = ppd->dd;
        struct rvt_dev_info *rdi = &dd->verbs_dev.rdi;
        u8 rcv_type = rhf_rcv_type(packet->rhf);
        u8 rte = rhf_rcv_type_err(packet->rhf);
        struct ib_header *hdr = packet->hdr;
        struct ib_other_headers *ohdr = NULL;
        int lnh = be16_to_cpu(hdr->lrh[0]) & 3;
        u16 lid  = be16_to_cpu(hdr->lrh[1]);
        u8 opcode;
        u32 qp_num, psn, ibpsn;
        struct rvt_qp *qp;
        struct hfi1_qp_priv *qpriv;
        unsigned long flags;
        bool ret = true;
        struct rvt_ack_entry *e;
        struct tid_rdma_request *req;
        struct tid_rdma_flow *flow;
        int diff = 0;

        trace_hfi1_msg_handle_kdeth_eflags(NULL, "Kdeth error: rhf ",
                                           packet->rhf);
        if (packet->rhf & RHF_ICRC_ERR)
                return ret;

        packet->ohdr = &hdr->u.oth;
        ohdr = packet->ohdr;
        trace_input_ibhdr(rcd->dd, packet, !!(rhf_dc_info(packet->rhf)));

        /* Get the destination QP number. */
        qp_num = be32_to_cpu(ohdr->u.tid_rdma.r_rsp.verbs_qp) &
                RVT_QPN_MASK;
        if (lid >= be16_to_cpu(IB_MULTICAST_LID_BASE))
                goto drop;

        psn = mask_psn(be32_to_cpu(ohdr->bth[2]));
        opcode = (be32_to_cpu(ohdr->bth[0]) >> 24) & 0xff;

        rcu_read_lock();
        qp = rvt_lookup_qpn(rdi, &ibp->rvp, qp_num);
        if (!qp)
                goto rcu_unlock;

        packet->qp = qp;

        /* Check for valid receive state. */
        spin_lock_irqsave(&qp->r_lock, flags);
        if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK)) {
                ibp->rvp.n_pkt_drops++;
                goto r_unlock;
        }

        if (packet->rhf & RHF_TID_ERR) {
                /* For TIDERR and RC QPs preemptively schedule a NAK */
                u32 tlen = rhf_pkt_len(packet->rhf); /* in bytes */

                /* Sanity check packet */
                if (tlen < 24)
                        goto r_unlock;

                /*
                 * Check for GRH. We should never get packets with GRH in this
                 * path.
                 */
                if (lnh == HFI1_LRH_GRH)
                        goto r_unlock;

                if (tid_rdma_tid_err(packet, rcv_type))
                        goto r_unlock;
        }

        /* handle TID RDMA READ */
        if (opcode == TID_OP(READ_RESP)) {
                ibpsn = be32_to_cpu(ohdr->u.tid_rdma.r_rsp.verbs_psn);
                ibpsn = mask_psn(ibpsn);
                ret = handle_read_kdeth_eflags(rcd, packet, rcv_type, rte, psn,
                                               ibpsn);
                goto r_unlock;
        }

        /*
         * qp->s_tail_ack_queue points to the rvt_ack_entry currently being
         * processed. These a completed sequentially so we can be sure that
         * the pointer will not change until the entire request has completed.
         */
        spin_lock(&qp->s_lock);
        qpriv = qp->priv;
        if (qpriv->r_tid_tail == HFI1_QP_WQE_INVALID ||
            qpriv->r_tid_tail == qpriv->r_tid_head)
                goto unlock;
        e = &qp->s_ack_queue[qpriv->r_tid_tail];
        if (e->opcode != TID_OP(WRITE_REQ))
                goto unlock;
        req = ack_to_tid_req(e);
        if (req->comp_seg == req->cur_seg)
                goto unlock;
        flow = &req->flows[req->clear_tail];
        trace_hfi1_eflags_err_write(qp, rcv_type, rte, psn);
        trace_hfi1_rsp_handle_kdeth_eflags(qp, psn);
        trace_hfi1_tid_write_rsp_handle_kdeth_eflags(qp);
        trace_hfi1_tid_req_handle_kdeth_eflags(qp, 0, e->opcode, e->psn,
                                               e->lpsn, req);
        trace_hfi1_tid_flow_handle_kdeth_eflags(qp, req->clear_tail, flow);

        switch (rcv_type) {
        case RHF_RCV_TYPE_EXPECTED:
                switch (rte) {
                case RHF_RTE_EXPECTED_FLOW_SEQ_ERR:
                        if (!(qpriv->s_flags & HFI1_R_TID_SW_PSN)) {
                                qpriv->s_flags |= HFI1_R_TID_SW_PSN;
                                flow->flow_state.r_next_psn =
                                        read_r_next_psn(dd, rcd->ctxt,
                                                        flow->idx);
                                qpriv->r_next_psn_kdeth =
                                        flow->flow_state.r_next_psn;
                                goto nak_psn;
                        } else {
                                /*
                                 * If the received PSN does not match the next
                                 * expected PSN, NAK the packet.
                                 * However, only do that if we know that the a
                                 * NAK has already been sent. Otherwise, this
                                 * mismatch could be due to packets that were
                                 * already in flight.
                                 */
                                diff = cmp_psn(psn,
                                               flow->flow_state.r_next_psn);
                                if (diff > 0)
                                        goto nak_psn;
                                else if (diff < 0)
                                        break;

                                qpriv->s_nak_state = 0;
                                /*
                                 * If SW PSN verification is successful and this
                                 * is the last packet in the segment, tell the
                                 * caller to process it as a normal packet.
                                 */
                                if (psn == full_flow_psn(flow,
                                                         flow->flow_state.lpsn))
                                        ret = false;
                                flow->flow_state.r_next_psn =
                                        mask_psn(psn + 1);
                                qpriv->r_next_psn_kdeth =
                                        flow->flow_state.r_next_psn;
                        }
                        break;

                case RHF_RTE_EXPECTED_FLOW_GEN_ERR:
                        goto nak_psn;

                default:
                        break;
                }
                break;

        case RHF_RCV_TYPE_ERROR:
                switch (rte) {
                case RHF_RTE_ERROR_OP_CODE_ERR:
                case RHF_RTE_ERROR_KHDR_MIN_LEN_ERR:
                case RHF_RTE_ERROR_KHDR_HCRC_ERR:
                case RHF_RTE_ERROR_KHDR_KVER_ERR:
                case RHF_RTE_ERROR_CONTEXT_ERR:
                case RHF_RTE_ERROR_KHDR_TID_ERR:
                default:
                        break;
                }
                break;
        default:
                break;
        }

unlock:
        spin_unlock(&qp->s_lock);
r_unlock:
        spin_unlock_irqrestore(&qp->r_lock, flags);
rcu_unlock:
        rcu_read_unlock();
drop:
        return ret;
nak_psn:
        ibp->rvp.n_rc_seqnak++;
        if (!qpriv->s_nak_state) {
                qpriv->s_nak_state = IB_NAK_PSN_ERROR;
                /* We are NAK'ing the next expected PSN */
                qpriv->s_nak_psn = mask_psn(flow->flow_state.r_next_psn);
                tid_rdma_trigger_ack(qp);
        }
        goto unlock;
}

/*
 * "Rewind" the TID request information.
 * This means that we reset the state back to ACTIVE,
 * find the proper flow, set the flow index to that flow,
 * and reset the flow information.
 */
void hfi1_tid_rdma_restart_req(struct rvt_qp *qp, struct rvt_swqe *wqe,
                               u32 *bth2)
{
        struct tid_rdma_request *req = wqe_to_tid_req(wqe);
        struct tid_rdma_flow *flow;
        struct hfi1_qp_priv *qpriv = qp->priv;
        int diff, delta_pkts;
        u32 tididx = 0, i;
        u16 fidx;

        if (wqe->wr.opcode == IB_WR_TID_RDMA_READ) {
                *bth2 = mask_psn(qp->s_psn);
                flow = find_flow_ib(req, *bth2, &fidx);
                if (!flow) {
                        trace_hfi1_msg_tid_restart_req(/* msg */
                           qp, "!!!!!! Could not find flow to restart: bth2 ",
                           (u64)*bth2);
                        trace_hfi1_tid_req_restart_req(qp, 0, wqe->wr.opcode,
                                                       wqe->psn, wqe->lpsn,
                                                       req);
                        return;
                }
        } else {
                fidx = req->acked_tail;
                flow = &req->flows[fidx];
                *bth2 = mask_psn(req->r_ack_psn);
        }

        if (wqe->wr.opcode == IB_WR_TID_RDMA_READ)
                delta_pkts = delta_psn(*bth2, flow->flow_state.ib_spsn);
        else
                delta_pkts = delta_psn(*bth2,
                                       full_flow_psn(flow,
                                                     flow->flow_state.spsn));

        trace_hfi1_tid_flow_restart_req(qp, fidx, flow);
        diff = delta_pkts + flow->resync_npkts;

        flow->sent = 0;
        flow->pkt = 0;
        flow->tid_idx = 0;
        flow->tid_offset = 0;
        if (diff) {
                for (tididx = 0; tididx < flow->tidcnt; tididx++) {
                        u32 tidentry = flow->tid_entry[tididx], tidlen,
                                tidnpkts, npkts;

                        flow->tid_offset = 0;
                        tidlen = EXP_TID_GET(tidentry, LEN) * PAGE_SIZE;
                        tidnpkts = rvt_div_round_up_mtu(qp, tidlen);
                        npkts = min_t(u32, diff, tidnpkts);
                        flow->pkt += npkts;
                        flow->sent += (npkts == tidnpkts ? tidlen :
                                       npkts * qp->pmtu);
                        flow->tid_offset += npkts * qp->pmtu;
                        diff -= npkts;
                        if (!diff)
                                break;
                }
        }
        if (wqe->wr.opcode == IB_WR_TID_RDMA_WRITE) {
                rvt_skip_sge(&qpriv->tid_ss, (req->cur_seg * req->seg_len) +
                             flow->sent, 0);
                /*
                 * Packet PSN is based on flow_state.spsn + flow->pkt. However,
                 * during a RESYNC, the generation is incremented and the
                 * sequence is reset to 0. Since we've adjusted the npkts in the
                 * flow and the SGE has been sufficiently advanced, we have to
                 * adjust flow->pkt in order to calculate the correct PSN.
                 */
                flow->pkt -= flow->resync_npkts;
        }

        if (flow->tid_offset ==
            EXP_TID_GET(flow->tid_entry[tididx], LEN) * PAGE_SIZE) {
                tididx++;
                flow->tid_offset = 0;
        }
        flow->tid_idx = tididx;
        if (wqe->wr.opcode == IB_WR_TID_RDMA_READ)
                /* Move flow_idx to correct index */
                req->flow_idx = fidx;
        else
                req->clear_tail = fidx;

        trace_hfi1_tid_flow_restart_req(qp, fidx, flow);
        trace_hfi1_tid_req_restart_req(qp, 0, wqe->wr.opcode, wqe->psn,
                                       wqe->lpsn, req);
        req->state = TID_REQUEST_ACTIVE;
        if (wqe->wr.opcode == IB_WR_TID_RDMA_WRITE) {
                /* Reset all the flows that we are going to resend */
                fidx = CIRC_NEXT(fidx, MAX_FLOWS);
                i = qpriv->s_tid_tail;
                do {
                        for (; CIRC_CNT(req->setup_head, fidx, MAX_FLOWS);
                              fidx = CIRC_NEXT(fidx, MAX_FLOWS)) {
                                req->flows[fidx].sent = 0;
                                req->flows[fidx].pkt = 0;
                                req->flows[fidx].tid_idx = 0;
                                req->flows[fidx].tid_offset = 0;
                                req->flows[fidx].resync_npkts = 0;
                        }
                        if (i == qpriv->s_tid_cur)
                                break;
                        do {
                                i = (++i == qp->s_size ? 0 : i);
                                wqe = rvt_get_swqe_ptr(qp, i);
                        } while (wqe->wr.opcode != IB_WR_TID_RDMA_WRITE);
                        req = wqe_to_tid_req(wqe);
                        req->cur_seg = req->ack_seg;
                        fidx = req->acked_tail;
                        /* Pull req->clear_tail back */
                        req->clear_tail = fidx;
                } while (1);
        }
}

void hfi1_qp_kern_exp_rcv_clear_all(struct rvt_qp *qp)
{
        int i, ret;
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct tid_flow_state *fs;

        if (qp->ibqp.qp_type != IB_QPT_RC || !HFI1_CAP_IS_KSET(TID_RDMA))
                return;

        /*
         * First, clear the flow to help prevent any delayed packets from
         * being delivered.
         */
        fs = &qpriv->flow_state;
        if (fs->index != RXE_NUM_TID_FLOWS)
                hfi1_kern_clear_hw_flow(qpriv->rcd, qp);

        for (i = qp->s_acked; i != qp->s_head;) {
                struct rvt_swqe *wqe = rvt_get_swqe_ptr(qp, i);

                if (++i == qp->s_size)
                        i = 0;
                /* Free only locally allocated TID entries */
                if (wqe->wr.opcode != IB_WR_TID_RDMA_READ)
                        continue;
                do {
                        struct hfi1_swqe_priv *priv = wqe->priv;

                        ret = hfi1_kern_exp_rcv_clear(&priv->tid_req);
                } while (!ret);
        }
        for (i = qp->s_acked_ack_queue; i != qp->r_head_ack_queue;) {
                struct rvt_ack_entry *e = &qp->s_ack_queue[i];

                if (++i == rvt_max_atomic(ib_to_rvt(qp->ibqp.device)))
                        i = 0;
                /* Free only locally allocated TID entries */
                if (e->opcode != TID_OP(WRITE_REQ))
                        continue;
                do {
                        struct hfi1_ack_priv *priv = e->priv;

                        ret = hfi1_kern_exp_rcv_clear(&priv->tid_req);
                } while (!ret);
        }
}

bool hfi1_tid_rdma_wqe_interlock(struct rvt_qp *qp, struct rvt_swqe *wqe)
{
        struct rvt_swqe *prev;
        struct hfi1_qp_priv *priv = qp->priv;
        u32 s_prev;
        struct tid_rdma_request *req;

        s_prev = (qp->s_cur == 0 ? qp->s_size : qp->s_cur) - 1;
        prev = rvt_get_swqe_ptr(qp, s_prev);

        switch (wqe->wr.opcode) {
        case IB_WR_SEND:
        case IB_WR_SEND_WITH_IMM:
        case IB_WR_SEND_WITH_INV:
        case IB_WR_ATOMIC_CMP_AND_SWP:
        case IB_WR_ATOMIC_FETCH_AND_ADD:
        case IB_WR_RDMA_WRITE:
        case IB_WR_RDMA_WRITE_WITH_IMM:
                switch (prev->wr.opcode) {
                case IB_WR_TID_RDMA_WRITE:
                        req = wqe_to_tid_req(prev);
                        if (req->ack_seg != req->total_segs)
                                goto interlock;
                        break;
                default:
                        break;
                }
                break;
        case IB_WR_RDMA_READ:
                if (prev->wr.opcode != IB_WR_TID_RDMA_WRITE)
                        break;
                fallthrough;
        case IB_WR_TID_RDMA_READ:
                switch (prev->wr.opcode) {
                case IB_WR_RDMA_READ:
                        if (qp->s_acked != qp->s_cur)
                                goto interlock;
                        break;
                case IB_WR_TID_RDMA_WRITE:
                        req = wqe_to_tid_req(prev);
                        if (req->ack_seg != req->total_segs)
                                goto interlock;
                        break;
                default:
                        break;
                }
                break;
        default:
                break;
        }
        return false;

interlock:
        priv->s_flags |= HFI1_S_TID_WAIT_INTERLCK;
        return true;
}

/* Does @sge meet the alignment requirements for tid rdma? */
static inline bool hfi1_check_sge_align(struct rvt_qp *qp,
                                        struct rvt_sge *sge, int num_sge)
{
        int i;

        for (i = 0; i < num_sge; i++, sge++) {
                trace_hfi1_sge_check_align(qp, i, sge);
                if ((u64)sge->vaddr & ~PAGE_MASK ||
                    sge->sge_length & ~PAGE_MASK)
                        return false;
        }
        return true;
}

void setup_tid_rdma_wqe(struct rvt_qp *qp, struct rvt_swqe *wqe)
{
        struct hfi1_qp_priv *qpriv = (struct hfi1_qp_priv *)qp->priv;
        struct hfi1_swqe_priv *priv = wqe->priv;
        struct tid_rdma_params *remote;
        enum ib_wr_opcode new_opcode;
        bool do_tid_rdma = false;
        struct hfi1_pportdata *ppd = qpriv->rcd->ppd;

        if ((rdma_ah_get_dlid(&qp->remote_ah_attr) & ~((1 << ppd->lmc) - 1)) ==
                                ppd->lid)
                return;
        if (qpriv->hdr_type != HFI1_PKT_TYPE_9B)
                return;

        rcu_read_lock();
        remote = rcu_dereference(qpriv->tid_rdma.remote);
        /*
         * If TID RDMA is disabled by the negotiation, don't
         * use it.
         */
        if (!remote)
                goto exit;

        if (wqe->wr.opcode == IB_WR_RDMA_READ) {
                if (hfi1_check_sge_align(qp, &wqe->sg_list[0],
                                         wqe->wr.num_sge)) {
                        new_opcode = IB_WR_TID_RDMA_READ;
                        do_tid_rdma = true;
                }
        } else if (wqe->wr.opcode == IB_WR_RDMA_WRITE) {
                /*
                 * TID RDMA is enabled for this RDMA WRITE request iff:
                 *   1. The remote address is page-aligned,
                 *   2. The length is larger than the minimum segment size,
                 *   3. The length is page-multiple.
                 */
                if (!(wqe->rdma_wr.remote_addr & ~PAGE_MASK) &&
                    !(wqe->length & ~PAGE_MASK)) {
                        new_opcode = IB_WR_TID_RDMA_WRITE;
                        do_tid_rdma = true;
                }
        }

        if (do_tid_rdma) {
                if (hfi1_kern_exp_rcv_alloc_flows(&priv->tid_req, GFP_ATOMIC))
                        goto exit;
                wqe->wr.opcode = new_opcode;
                priv->tid_req.seg_len =
                        min_t(u32, remote->max_len, wqe->length);
                priv->tid_req.total_segs =
                        DIV_ROUND_UP(wqe->length, priv->tid_req.seg_len);
                /* Compute the last PSN of the request */
                wqe->lpsn = wqe->psn;
                if (wqe->wr.opcode == IB_WR_TID_RDMA_READ) {
                        priv->tid_req.n_flows = remote->max_read;
                        qpriv->tid_r_reqs++;
                        wqe->lpsn += rvt_div_round_up_mtu(qp, wqe->length) - 1;
                } else {
                        wqe->lpsn += priv->tid_req.total_segs - 1;
                        atomic_inc(&qpriv->n_requests);
                }

                priv->tid_req.cur_seg = 0;
                priv->tid_req.comp_seg = 0;
                priv->tid_req.ack_seg = 0;
                priv->tid_req.state = TID_REQUEST_INACTIVE;
                /*
                 * Reset acked_tail.
                 * TID RDMA READ does not have ACKs so it does not
                 * update the pointer. We have to reset it so TID RDMA
                 * WRITE does not get confused.
                 */
                priv->tid_req.acked_tail = priv->tid_req.setup_head;
                trace_hfi1_tid_req_setup_tid_wqe(qp, 1, wqe->wr.opcode,
                                                 wqe->psn, wqe->lpsn,
                                                 &priv->tid_req);
        }
exit:
        rcu_read_unlock();
}

/* TID RDMA WRITE functions */

u32 hfi1_build_tid_rdma_write_req(struct rvt_qp *qp, struct rvt_swqe *wqe,
                                  struct ib_other_headers *ohdr,
                                  u32 *bth1, u32 *bth2, u32 *len)
{
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct tid_rdma_request *req = wqe_to_tid_req(wqe);
        struct tid_rdma_params *remote;

        rcu_read_lock();
        remote = rcu_dereference(qpriv->tid_rdma.remote);
        /*
         * Set the number of flow to be used based on negotiated
         * parameters.
         */
        req->n_flows = remote->max_write;
        req->state = TID_REQUEST_ACTIVE;

        KDETH_RESET(ohdr->u.tid_rdma.w_req.kdeth0, KVER, 0x1);
        KDETH_RESET(ohdr->u.tid_rdma.w_req.kdeth1, JKEY, remote->jkey);
        ohdr->u.tid_rdma.w_req.reth.vaddr =
                cpu_to_be64(wqe->rdma_wr.remote_addr + (wqe->length - *len));
        ohdr->u.tid_rdma.w_req.reth.rkey =
                cpu_to_be32(wqe->rdma_wr.rkey);
        ohdr->u.tid_rdma.w_req.reth.length = cpu_to_be32(*len);
        ohdr->u.tid_rdma.w_req.verbs_qp = cpu_to_be32(qp->remote_qpn);
        *bth1 &= ~RVT_QPN_MASK;
        *bth1 |= remote->qp;
        qp->s_state = TID_OP(WRITE_REQ);
        qp->s_flags |= HFI1_S_WAIT_TID_RESP;
        *bth2 |= IB_BTH_REQ_ACK;
        *len = 0;

        rcu_read_unlock();
        return sizeof(ohdr->u.tid_rdma.w_req) / sizeof(u32);
}

static u32 hfi1_compute_tid_rdma_flow_wt(struct rvt_qp *qp)
{
        /*
         * Heuristic for computing the RNR timeout when waiting on the flow
         * queue. Rather than a computationaly expensive exact estimate of when
         * a flow will be available, we assume that if a QP is at position N in
         * the flow queue it has to wait approximately (N + 1) * (number of
         * segments between two sync points). The rationale for this is that
         * flows are released and recycled at each sync point.
         */
        return (MAX_TID_FLOW_PSN * qp->pmtu) >> TID_RDMA_SEGMENT_SHIFT;
}

static u32 position_in_queue(struct hfi1_qp_priv *qpriv,
                             struct tid_queue *queue)
{
        return qpriv->tid_enqueue - queue->dequeue;
}

/*
 * @qp: points to rvt_qp context.
 * @to_seg: desired RNR timeout in segments.
 * Return: index of the next highest timeout in the ib_hfi1_rnr_table[]
 */
static u32 hfi1_compute_tid_rnr_timeout(struct rvt_qp *qp, u32 to_seg)
{
        struct hfi1_qp_priv *qpriv = qp->priv;
        u64 timeout;
        u32 bytes_per_us;
        u8 i;

        bytes_per_us = active_egress_rate(qpriv->rcd->ppd) / 8;
        timeout = (to_seg * TID_RDMA_MAX_SEGMENT_SIZE) / bytes_per_us;
        /*
         * Find the next highest value in the RNR table to the required
         * timeout. This gives the responder some padding.
         */
        for (i = 1; i <= IB_AETH_CREDIT_MASK; i++)
                if (rvt_rnr_tbl_to_usec(i) >= timeout)
                        return i;
        return 0;
}

/*
 * Central place for resource allocation at TID write responder,
 * is called from write_req and write_data interrupt handlers as
 * well as the send thread when a queued QP is scheduled for
 * resource allocation.
 *
 * Iterates over (a) segments of a request and then (b) queued requests
 * themselves to allocate resources for up to local->max_write
 * segments across multiple requests. Stop allocating when we
 * hit a sync point, resume allocating after data packets at
 * sync point have been received.
 *
 * Resource allocation and sending of responses is decoupled. The
 * request/segment which are being allocated and sent are as follows.
 * Resources are allocated for:
 *     [request: qpriv->r_tid_alloc, segment: req->alloc_seg]
 * The send thread sends:
 *     [request: qp->s_tail_ack_queue, segment:req->cur_seg]
 */
static void hfi1_tid_write_alloc_resources(struct rvt_qp *qp, bool intr_ctx)
{
        struct tid_rdma_request *req;
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct hfi1_ctxtdata *rcd = qpriv->rcd;
        struct tid_rdma_params *local = &qpriv->tid_rdma.local;
        struct rvt_ack_entry *e;
        u32 npkts, to_seg;
        bool last;
        int ret = 0;

        lockdep_assert_held(&qp->s_lock);

        while (1) {
                trace_hfi1_rsp_tid_write_alloc_res(qp, 0);
                trace_hfi1_tid_write_rsp_alloc_res(qp);
                /*
                 * Don't allocate more segments if a RNR NAK has already been
                 * scheduled to avoid messing up qp->r_psn: the RNR NAK will
                 * be sent only when all allocated segments have been sent.
                 * However, if more segments are allocated before that, TID RDMA
                 * WRITE RESP packets will be sent out for these new segments
                 * before the RNR NAK packet. When the requester receives the
                 * RNR NAK packet, it will restart with qp->s_last_psn + 1,
                 * which does not match qp->r_psn and will be dropped.
                 * Consequently, the requester will exhaust its retries and
                 * put the qp into error state.
                 */
                if (qpriv->rnr_nak_state == TID_RNR_NAK_SEND)
                        break;

                /* No requests left to process */
                if (qpriv->r_tid_alloc == qpriv->r_tid_head) {
                        /* If all data has been received, clear the flow */
                        if (qpriv->flow_state.index < RXE_NUM_TID_FLOWS &&
                            !qpriv->alloc_w_segs) {
                                hfi1_kern_clear_hw_flow(rcd, qp);
                                qpriv->s_flags &= ~HFI1_R_TID_SW_PSN;
                        }
                        break;
                }

                e = &qp->s_ack_queue[qpriv->r_tid_alloc];
                if (e->opcode != TID_OP(WRITE_REQ))
                        goto next_req;
                req = ack_to_tid_req(e);
                trace_hfi1_tid_req_write_alloc_res(qp, 0, e->opcode, e->psn,
                                                   e->lpsn, req);
                /* Finished allocating for all segments of this request */
                if (req->alloc_seg >= req->total_segs)
                        goto next_req;

                /* Can allocate only a maximum of local->max_write for a QP */
                if (qpriv->alloc_w_segs >= local->max_write)
                        break;

                /* Don't allocate at a sync point with data packets pending */
                if (qpriv->sync_pt && qpriv->alloc_w_segs)
                        break;

                /* All data received at the sync point, continue */
                if (qpriv->sync_pt && !qpriv->alloc_w_segs) {
                        hfi1_kern_clear_hw_flow(rcd, qp);
                        qpriv->sync_pt = false;
                        qpriv->s_flags &= ~HFI1_R_TID_SW_PSN;
                }

                /* Allocate flow if we don't have one */
                if (qpriv->flow_state.index >= RXE_NUM_TID_FLOWS) {
                        ret = hfi1_kern_setup_hw_flow(qpriv->rcd, qp);
                        if (ret) {
                                to_seg = hfi1_compute_tid_rdma_flow_wt(qp) *
                                        position_in_queue(qpriv,
                                                          &rcd->flow_queue);
                                break;
                        }
                }

                npkts = rvt_div_round_up_mtu(qp, req->seg_len);

                /*
                 * We are at a sync point if we run out of KDETH PSN space.
                 * Last PSN of every generation is reserved for RESYNC.
                 */
                if (qpriv->flow_state.psn + npkts > MAX_TID_FLOW_PSN - 1) {
                        qpriv->sync_pt = true;
                        break;
                }

                /*
                 * If overtaking req->acked_tail, send an RNR NAK. Because the
                 * QP is not queued in this case, and the issue can only be
                 * caused by a delay in scheduling the second leg which we
                 * cannot estimate, we use a rather arbitrary RNR timeout of
                 * (MAX_FLOWS / 2) segments
                 */
                if (!CIRC_SPACE(req->setup_head, req->acked_tail,
                                MAX_FLOWS)) {
                        ret = -EAGAIN;
                        to_seg = MAX_FLOWS >> 1;
                        tid_rdma_trigger_ack(qp);
                        break;
                }

                /* Try to allocate rcv array / TID entries */
                ret = hfi1_kern_exp_rcv_setup(req, &req->ss, &last);
                if (ret == -EAGAIN)
                        to_seg = position_in_queue(qpriv, &rcd->rarr_queue);
                if (ret)
                        break;

                qpriv->alloc_w_segs++;
                req->alloc_seg++;
                continue;
next_req:
                /* Begin processing the next request */
                if (++qpriv->r_tid_alloc >
                    rvt_size_atomic(ib_to_rvt(qp->ibqp.device)))
                        qpriv->r_tid_alloc = 0;
        }

        /*
         * Schedule an RNR NAK to be sent if (a) flow or rcv array allocation
         * has failed (b) we are called from the rcv handler interrupt context
         * (c) an RNR NAK has not already been scheduled
         */
        if (ret == -EAGAIN && intr_ctx && !qp->r_nak_state)
                goto send_rnr_nak;

        return;

send_rnr_nak:
        lockdep_assert_held(&qp->r_lock);

        /* Set r_nak_state to prevent unrelated events from generating NAK's */
        qp->r_nak_state = hfi1_compute_tid_rnr_timeout(qp, to_seg) | IB_RNR_NAK;

        /* Pull back r_psn to the segment being RNR NAK'd */
        qp->r_psn = e->psn + req->alloc_seg;
        qp->r_ack_psn = qp->r_psn;
        /*
         * Pull back r_head_ack_queue to the ack entry following the request
         * being RNR NAK'd. This allows resources to be allocated to the request
         * if the queued QP is scheduled.
         */
        qp->r_head_ack_queue = qpriv->r_tid_alloc + 1;
        if (qp->r_head_ack_queue > rvt_size_atomic(ib_to_rvt(qp->ibqp.device)))
                qp->r_head_ack_queue = 0;
        qpriv->r_tid_head = qp->r_head_ack_queue;
        /*
         * These send side fields are used in make_rc_ack(). They are set in
         * hfi1_send_rc_ack() but must be set here before dropping qp->s_lock
         * for consistency
         */
        qp->s_nak_state = qp->r_nak_state;
        qp->s_ack_psn = qp->r_ack_psn;
        /*
         * Clear the ACK PENDING flag to prevent unwanted ACK because we
         * have modified qp->s_ack_psn here.
         */
        qp->s_flags &= ~(RVT_S_ACK_PENDING);

        trace_hfi1_rsp_tid_write_alloc_res(qp, qp->r_psn);
        /*
         * qpriv->rnr_nak_state is used to determine when the scheduled RNR NAK
         * has actually been sent. qp->s_flags RVT_S_ACK_PENDING bit cannot be
         * used for this because qp->s_lock is dropped before calling
         * hfi1_send_rc_ack() leading to inconsistency between the receive
         * interrupt handlers and the send thread in make_rc_ack()
         */
        qpriv->rnr_nak_state = TID_RNR_NAK_SEND;

        /*
         * Schedule RNR NAK to be sent. RNR NAK's are scheduled from the receive
         * interrupt handlers but will be sent from the send engine behind any
         * previous responses that may have been scheduled
         */
        rc_defered_ack(rcd, qp);
}

void hfi1_rc_rcv_tid_rdma_write_req(struct hfi1_packet *packet)
{
        /* HANDLER FOR TID RDMA WRITE REQUEST packet (Responder side)*/

        /*
         * 1. Verify TID RDMA WRITE REQ as per IB_OPCODE_RC_RDMA_WRITE_FIRST
         *    (see hfi1_rc_rcv())
         *     - Don't allow 0-length requests.
         * 2. Put TID RDMA WRITE REQ into the response queue (s_ack_queue)
         *     - Setup struct tid_rdma_req with request info
         *     - Prepare struct tid_rdma_flow array?
         * 3. Set the qp->s_ack_state as state diagram in design doc.
         * 4. Set RVT_S_RESP_PENDING in s_flags.
         * 5. Kick the send engine (hfi1_schedule_send())
         */
        struct hfi1_ctxtdata *rcd = packet->rcd;
        struct rvt_qp *qp = packet->qp;
        struct hfi1_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
        struct ib_other_headers *ohdr = packet->ohdr;
        struct rvt_ack_entry *e;
        unsigned long flags;
        struct ib_reth *reth;
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct tid_rdma_request *req;
        u32 bth0, psn, len, rkey, num_segs;
        bool fecn;
        u8 next;
        u64 vaddr;
        int diff;

        bth0 = be32_to_cpu(ohdr->bth[0]);
        if (hfi1_ruc_check_hdr(ibp, packet))
                return;

        fecn = process_ecn(qp, packet);
        psn = mask_psn(be32_to_cpu(ohdr->bth[2]));
        trace_hfi1_rsp_rcv_tid_write_req(qp, psn);

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

        if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_WRITE)))
                goto nack_inv;

        reth = &ohdr->u.tid_rdma.w_req.reth;
        vaddr = be64_to_cpu(reth->vaddr);
        len = be32_to_cpu(reth->length);

        num_segs = DIV_ROUND_UP(len, qpriv->tid_rdma.local.max_len);
        diff = delta_psn(psn, qp->r_psn);
        if (unlikely(diff)) {
                tid_rdma_rcv_err(packet, ohdr, qp, psn, diff, fecn);
                return;
        }

        /*
         * The resent request which was previously RNR NAK'd is inserted at the
         * location of the original request, which is one entry behind
         * r_head_ack_queue
         */
        if (qpriv->rnr_nak_state)
                qp->r_head_ack_queue = qp->r_head_ack_queue ?
                        qp->r_head_ack_queue - 1 :
                        rvt_size_atomic(ib_to_rvt(qp->ibqp.device));

        /* We've verified the request, insert it into the ack queue. */
        next = qp->r_head_ack_queue + 1;
        if (next > rvt_size_atomic(ib_to_rvt(qp->ibqp.device)))
                next = 0;
        spin_lock_irqsave(&qp->s_lock, flags);
        if (unlikely(next == qp->s_acked_ack_queue)) {
                if (!qp->s_ack_queue[next].sent)
                        goto nack_inv_unlock;
                update_ack_queue(qp, next);
        }
        e = &qp->s_ack_queue[qp->r_head_ack_queue];
        req = ack_to_tid_req(e);

        /* Bring previously RNR NAK'd request back to life */
        if (qpriv->rnr_nak_state) {
                qp->r_nak_state = 0;
                qp->s_nak_state = 0;
                qpriv->rnr_nak_state = TID_RNR_NAK_INIT;
                qp->r_psn = e->lpsn + 1;
                req->state = TID_REQUEST_INIT;
                goto update_head;
        }

        release_rdma_sge_mr(e);

        /* The length needs to be in multiples of PAGE_SIZE */
        if (!len || len & ~PAGE_MASK)
                goto nack_inv_unlock;

        rkey = be32_to_cpu(reth->rkey);
        qp->r_len = len;

        if (e->opcode == TID_OP(WRITE_REQ) &&
            (req->setup_head != req->clear_tail ||
             req->clear_tail != req->acked_tail))
                goto nack_inv_unlock;

        if (unlikely(!rvt_rkey_ok(qp, &e->rdma_sge, qp->r_len, vaddr,
                                  rkey, IB_ACCESS_REMOTE_WRITE)))
                goto nack_acc;

        qp->r_psn += num_segs - 1;

        e->opcode = (bth0 >> 24) & 0xff;
        e->psn = psn;
        e->lpsn = qp->r_psn;
        e->sent = 0;

        req->n_flows = min_t(u16, num_segs, qpriv->tid_rdma.local.max_write);
        req->state = TID_REQUEST_INIT;
        req->cur_seg = 0;
        req->comp_seg = 0;
        req->ack_seg = 0;
        req->alloc_seg = 0;
        req->isge = 0;
        req->seg_len = qpriv->tid_rdma.local.max_len;
        req->total_len = len;
        req->total_segs = num_segs;
        req->r_flow_psn = e->psn;
        req->ss.sge = e->rdma_sge;
        req->ss.num_sge = 1;

        req->flow_idx = req->setup_head;
        req->clear_tail = req->setup_head;
        req->acked_tail = req->setup_head;

        qp->r_state = e->opcode;
        qp->r_nak_state = 0;
        /*
         * We need to increment the MSN here instead of when we
         * finish sending the result since a duplicate request would
         * increment it more than once.
         */
        qp->r_msn++;
        qp->r_psn++;

        trace_hfi1_tid_req_rcv_write_req(qp, 0, e->opcode, e->psn, e->lpsn,
                                         req);

        if (qpriv->r_tid_tail == HFI1_QP_WQE_INVALID) {
                qpriv->r_tid_tail = qp->r_head_ack_queue;
        } else if (qpriv->r_tid_tail == qpriv->r_tid_head) {
                struct tid_rdma_request *ptr;

                e = &qp->s_ack_queue[qpriv->r_tid_tail];
                ptr = ack_to_tid_req(e);

                if (e->opcode != TID_OP(WRITE_REQ) ||
                    ptr->comp_seg == ptr->total_segs) {
                        if (qpriv->r_tid_tail == qpriv->r_tid_ack)
                                qpriv->r_tid_ack = qp->r_head_ack_queue;
                        qpriv->r_tid_tail = qp->r_head_ack_queue;
                }
        }
update_head:
        qp->r_head_ack_queue = next;
        qpriv->r_tid_head = qp->r_head_ack_queue;

        hfi1_tid_write_alloc_resources(qp, true);
        trace_hfi1_tid_write_rsp_rcv_req(qp);

        /* Schedule the send tasklet. */
        qp->s_flags |= RVT_S_RESP_PENDING;
        if (fecn)
                qp->s_flags |= RVT_S_ECN;
        hfi1_schedule_send(qp);

        spin_unlock_irqrestore(&qp->s_lock, flags);
        return;

nack_inv_unlock:
        spin_unlock_irqrestore(&qp->s_lock, flags);
nack_inv:
        rvt_rc_error(qp, IB_WC_LOC_QP_OP_ERR);
        qp->r_nak_state = IB_NAK_INVALID_REQUEST;
        qp->r_ack_psn = qp->r_psn;
        /* Queue NAK for later */
        rc_defered_ack(rcd, qp);
        return;
nack_acc:
        spin_unlock_irqrestore(&qp->s_lock, flags);
        rvt_rc_error(qp, IB_WC_LOC_PROT_ERR);
        qp->r_nak_state = IB_NAK_REMOTE_ACCESS_ERROR;
        qp->r_ack_psn = qp->r_psn;
}

u32 hfi1_build_tid_rdma_write_resp(struct rvt_qp *qp, struct rvt_ack_entry *e,
                                   struct ib_other_headers *ohdr, u32 *bth1,
                                   u32 bth2, u32 *len,
                                   struct rvt_sge_state **ss)
{
        struct hfi1_ack_priv *epriv = e->priv;
        struct tid_rdma_request *req = &epriv->tid_req;
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct tid_rdma_flow *flow = NULL;
        u32 resp_len = 0, hdwords = 0;
        void *resp_addr = NULL;
        struct tid_rdma_params *remote;

        trace_hfi1_tid_req_build_write_resp(qp, 0, e->opcode, e->psn, e->lpsn,
                                            req);
        trace_hfi1_tid_write_rsp_build_resp(qp);
        trace_hfi1_rsp_build_tid_write_resp(qp, bth2);
        flow = &req->flows[req->flow_idx];
        switch (req->state) {
        default:
                /*
                 * Try to allocate resources here in case QP was queued and was
                 * later scheduled when resources became available
                 */
                hfi1_tid_write_alloc_resources(qp, false);

                /* We've already sent everything which is ready */
                if (req->cur_seg >= req->alloc_seg)
                        goto done;

                /*
                 * Resources can be assigned but responses cannot be sent in
                 * rnr_nak state, till the resent request is received
                 */
                if (qpriv->rnr_nak_state == TID_RNR_NAK_SENT)
                        goto done;

                req->state = TID_REQUEST_ACTIVE;
                trace_hfi1_tid_flow_build_write_resp(qp, req->flow_idx, flow);
                req->flow_idx = CIRC_NEXT(req->flow_idx, MAX_FLOWS);
                hfi1_add_tid_reap_timer(qp);
                break;

        case TID_REQUEST_RESEND_ACTIVE:
        case TID_REQUEST_RESEND:
                trace_hfi1_tid_flow_build_write_resp(qp, req->flow_idx, flow);
                req->flow_idx = CIRC_NEXT(req->flow_idx, MAX_FLOWS);
                if (!CIRC_CNT(req->setup_head, req->flow_idx, MAX_FLOWS))
                        req->state = TID_REQUEST_ACTIVE;

                hfi1_mod_tid_reap_timer(qp);
                break;
        }
        flow->flow_state.resp_ib_psn = bth2;
        resp_addr = (void *)flow->tid_entry;
        resp_len = sizeof(*flow->tid_entry) * flow->tidcnt;
        req->cur_seg++;

        memset(&ohdr->u.tid_rdma.w_rsp, 0, sizeof(ohdr->u.tid_rdma.w_rsp));
        epriv->ss.sge.vaddr = resp_addr;
        epriv->ss.sge.sge_length = resp_len;
        epriv->ss.sge.length = epriv->ss.sge.sge_length;
        /*
         * We can safely zero these out. Since the first SGE covers the
         * entire packet, nothing else should even look at the MR.
         */
        epriv->ss.sge.mr = NULL;
        epriv->ss.sge.m = 0;
        epriv->ss.sge.n = 0;

        epriv->ss.sg_list = NULL;
        epriv->ss.total_len = epriv->ss.sge.sge_length;
        epriv->ss.num_sge = 1;

        *ss = &epriv->ss;
        *len = epriv->ss.total_len;

        /* Construct the TID RDMA WRITE RESP packet header */
        rcu_read_lock();
        remote = rcu_dereference(qpriv->tid_rdma.remote);

        KDETH_RESET(ohdr->u.tid_rdma.w_rsp.kdeth0, KVER, 0x1);
        KDETH_RESET(ohdr->u.tid_rdma.w_rsp.kdeth1, JKEY, remote->jkey);
        ohdr->u.tid_rdma.w_rsp.aeth = rvt_compute_aeth(qp);
        ohdr->u.tid_rdma.w_rsp.tid_flow_psn =
                cpu_to_be32((flow->flow_state.generation <<
                             HFI1_KDETH_BTH_SEQ_SHIFT) |
                            (flow->flow_state.spsn &
                             HFI1_KDETH_BTH_SEQ_MASK));
        ohdr->u.tid_rdma.w_rsp.tid_flow_qp =
                cpu_to_be32(qpriv->tid_rdma.local.qp |
                            ((flow->idx & TID_RDMA_DESTQP_FLOW_MASK) <<
                             TID_RDMA_DESTQP_FLOW_SHIFT) |
                            qpriv->rcd->ctxt);
        ohdr->u.tid_rdma.w_rsp.verbs_qp = cpu_to_be32(qp->remote_qpn);
        *bth1 = remote->qp;
        rcu_read_unlock();
        hdwords = sizeof(ohdr->u.tid_rdma.w_rsp) / sizeof(u32);
        qpriv->pending_tid_w_segs++;
done:
        return hdwords;
}

static void hfi1_add_tid_reap_timer(struct rvt_qp *qp)
{
        struct hfi1_qp_priv *qpriv = qp->priv;

        lockdep_assert_held(&qp->s_lock);
        if (!(qpriv->s_flags & HFI1_R_TID_RSC_TIMER)) {
                qpriv->s_flags |= HFI1_R_TID_RSC_TIMER;
                qpriv->s_tid_timer.expires = jiffies +
                        qpriv->tid_timer_timeout_jiffies;
                add_timer(&qpriv->s_tid_timer);
        }
}

static void hfi1_mod_tid_reap_timer(struct rvt_qp *qp)
{
        struct hfi1_qp_priv *qpriv = qp->priv;

        lockdep_assert_held(&qp->s_lock);
        qpriv->s_flags |= HFI1_R_TID_RSC_TIMER;
        mod_timer(&qpriv->s_tid_timer, jiffies +
                  qpriv->tid_timer_timeout_jiffies);
}

static int hfi1_stop_tid_reap_timer(struct rvt_qp *qp)
{
        struct hfi1_qp_priv *qpriv = qp->priv;
        int rval = 0;

        lockdep_assert_held(&qp->s_lock);
        if (qpriv->s_flags & HFI1_R_TID_RSC_TIMER) {
                rval = del_timer(&qpriv->s_tid_timer);
                qpriv->s_flags &= ~HFI1_R_TID_RSC_TIMER;
        }
        return rval;
}

void hfi1_del_tid_reap_timer(struct rvt_qp *qp)
{
        struct hfi1_qp_priv *qpriv = qp->priv;

        del_timer_sync(&qpriv->s_tid_timer);
        qpriv->s_flags &= ~HFI1_R_TID_RSC_TIMER;
}

static void hfi1_tid_timeout(struct timer_list *t)
{
        struct hfi1_qp_priv *qpriv = from_timer(qpriv, t, s_tid_timer);
        struct rvt_qp *qp = qpriv->owner;
        struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);
        unsigned long flags;
        u32 i;

        spin_lock_irqsave(&qp->r_lock, flags);
        spin_lock(&qp->s_lock);
        if (qpriv->s_flags & HFI1_R_TID_RSC_TIMER) {
                dd_dev_warn(dd_from_ibdev(qp->ibqp.device), "[QP%u] %s %d\n",
                            qp->ibqp.qp_num, __func__, __LINE__);
                trace_hfi1_msg_tid_timeout(/* msg */
                        qp, "resource timeout = ",
                        (u64)qpriv->tid_timer_timeout_jiffies);
                hfi1_stop_tid_reap_timer(qp);
                /*
                 * Go though the entire ack queue and clear any outstanding
                 * HW flow and RcvArray resources.
                 */
                hfi1_kern_clear_hw_flow(qpriv->rcd, qp);
                for (i = 0; i < rvt_max_atomic(rdi); i++) {
                        struct tid_rdma_request *req =
                                ack_to_tid_req(&qp->s_ack_queue[i]);

                        hfi1_kern_exp_rcv_clear_all(req);
                }
                spin_unlock(&qp->s_lock);
                if (qp->ibqp.event_handler) {
                        struct ib_event ev;

                        ev.device = qp->ibqp.device;
                        ev.element.qp = &qp->ibqp;
                        ev.event = IB_EVENT_QP_FATAL;
                        qp->ibqp.event_handler(&ev, qp->ibqp.qp_context);
                }
                rvt_rc_error(qp, IB_WC_RESP_TIMEOUT_ERR);
                goto unlock_r_lock;
        }
        spin_unlock(&qp->s_lock);
unlock_r_lock:
        spin_unlock_irqrestore(&qp->r_lock, flags);
}

void hfi1_rc_rcv_tid_rdma_write_resp(struct hfi1_packet *packet)
{
        /* HANDLER FOR TID RDMA WRITE RESPONSE packet (Requester side) */

        /*
         * 1. Find matching SWQE
         * 2. Check that TIDENTRY array has enough space for a complete
         *    segment. If not, put QP in error state.
         * 3. Save response data in struct tid_rdma_req and struct tid_rdma_flow
         * 4. Remove HFI1_S_WAIT_TID_RESP from s_flags.
         * 5. Set qp->s_state
         * 6. Kick the send engine (hfi1_schedule_send())
         */
        struct ib_other_headers *ohdr = packet->ohdr;
        struct rvt_qp *qp = packet->qp;
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct hfi1_ctxtdata *rcd = packet->rcd;
        struct rvt_swqe *wqe;
        struct tid_rdma_request *req;
        struct tid_rdma_flow *flow;
        enum ib_wc_status status;
        u32 opcode, aeth, psn, flow_psn, i, tidlen = 0, pktlen;
        bool fecn;
        unsigned long flags;

        fecn = process_ecn(qp, packet);
        psn = mask_psn(be32_to_cpu(ohdr->bth[2]));
        aeth = be32_to_cpu(ohdr->u.tid_rdma.w_rsp.aeth);
        opcode = (be32_to_cpu(ohdr->bth[0]) >> 24) & 0xff;

        spin_lock_irqsave(&qp->s_lock, flags);

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

        /* Ignore duplicate responses. */
        if (unlikely(cmp_psn(psn, qp->s_last_psn) <= 0))
                goto ack_done;

        if (unlikely(qp->s_acked == qp->s_tail))
                goto ack_done;

        /*
         * If we are waiting for a particular packet sequence number
         * due to a request being resent, check for it. Otherwise,
         * ensure that we haven't missed anything.
         */
        if (qp->r_flags & RVT_R_RDMAR_SEQ) {
                if (cmp_psn(psn, qp->s_last_psn + 1) != 0)
                        goto ack_done;
                qp->r_flags &= ~RVT_R_RDMAR_SEQ;
        }

        wqe = rvt_get_swqe_ptr(qp, qpriv->s_tid_cur);
        if (unlikely(wqe->wr.opcode != IB_WR_TID_RDMA_WRITE))
                goto ack_op_err;

        req = wqe_to_tid_req(wqe);
        /*
         * If we've lost ACKs and our acked_tail pointer is too far
         * behind, don't overwrite segments. Just drop the packet and
         * let the reliability protocol take care of it.
         */
        if (!CIRC_SPACE(req->setup_head, req->acked_tail, MAX_FLOWS))
                goto ack_done;

        /*
         * The call to do_rc_ack() should be last in the chain of
         * packet checks because it will end up updating the QP state.
         * Therefore, anything that would prevent the packet from
         * being accepted as a successful response should be prior
         * to it.
         */
        if (!do_rc_ack(qp, aeth, psn, opcode, 0, rcd))
                goto ack_done;

        trace_hfi1_ack(qp, psn);

        flow = &req->flows[req->setup_head];
        flow->pkt = 0;
        flow->tid_idx = 0;
        flow->tid_offset = 0;
        flow->sent = 0;
        flow->resync_npkts = 0;
        flow->tid_qpn = be32_to_cpu(ohdr->u.tid_rdma.w_rsp.tid_flow_qp);
        flow->idx = (flow->tid_qpn >> TID_RDMA_DESTQP_FLOW_SHIFT) &
                TID_RDMA_DESTQP_FLOW_MASK;
        flow_psn = mask_psn(be32_to_cpu(ohdr->u.tid_rdma.w_rsp.tid_flow_psn));
        flow->flow_state.generation = flow_psn >> HFI1_KDETH_BTH_SEQ_SHIFT;
        flow->flow_state.spsn = flow_psn & HFI1_KDETH_BTH_SEQ_MASK;
        flow->flow_state.resp_ib_psn = psn;
        flow->length = min_t(u32, req->seg_len,
                             (wqe->length - (req->comp_seg * req->seg_len)));

        flow->npkts = rvt_div_round_up_mtu(qp, flow->length);
        flow->flow_state.lpsn = flow->flow_state.spsn +
                flow->npkts - 1;
        /* payload length = packet length - (header length + ICRC length) */
        pktlen = packet->tlen - (packet->hlen + 4);
        if (pktlen > sizeof(flow->tid_entry)) {
                status = IB_WC_LOC_LEN_ERR;
                goto ack_err;
        }
        memcpy(flow->tid_entry, packet->ebuf, pktlen);
        flow->tidcnt = pktlen / sizeof(*flow->tid_entry);
        trace_hfi1_tid_flow_rcv_write_resp(qp, req->setup_head, flow);

        req->comp_seg++;
        trace_hfi1_tid_write_sender_rcv_resp(qp, 0);
        /*
         * Walk the TID_ENTRY list to make sure we have enough space for a
         * complete segment.
         */
        for (i = 0; i < flow->tidcnt; i++) {
                trace_hfi1_tid_entry_rcv_write_resp(/* entry */
                        qp, i, flow->tid_entry[i]);
                if (!EXP_TID_GET(flow->tid_entry[i], LEN)) {
                        status = IB_WC_LOC_LEN_ERR;
                        goto ack_err;
                }
                tidlen += EXP_TID_GET(flow->tid_entry[i], LEN);
        }
        if (tidlen * PAGE_SIZE < flow->length) {
                status = IB_WC_LOC_LEN_ERR;
                goto ack_err;
        }

        trace_hfi1_tid_req_rcv_write_resp(qp, 0, wqe->wr.opcode, wqe->psn,
                                          wqe->lpsn, req);
        /*
         * If this is the first response for this request, set the initial
         * flow index to the current flow.
         */
        if (!cmp_psn(psn, wqe->psn)) {
                req->r_last_acked = mask_psn(wqe->psn - 1);
                /* Set acked flow index to head index */
                req->acked_tail = req->setup_head;
        }

        /* advance circular buffer head */
        req->setup_head = CIRC_NEXT(req->setup_head, MAX_FLOWS);
        req->state = TID_REQUEST_ACTIVE;

        /*
         * If all responses for this TID RDMA WRITE request have been received
         * advance the pointer to the next one.
         * Since TID RDMA requests could be mixed in with regular IB requests,
         * they might not appear sequentially in the queue. Therefore, the
         * next request needs to be "found".
         */
        if (qpriv->s_tid_cur != qpriv->s_tid_head &&
            req->comp_seg == req->total_segs) {
                for (i = qpriv->s_tid_cur + 1; ; i++) {
                        if (i == qp->s_size)
                                i = 0;
                        wqe = rvt_get_swqe_ptr(qp, i);
                        if (i == qpriv->s_tid_head)
                                break;
                        if (wqe->wr.opcode == IB_WR_TID_RDMA_WRITE)
                                break;
                }
                qpriv->s_tid_cur = i;
        }
        qp->s_flags &= ~HFI1_S_WAIT_TID_RESP;
        hfi1_schedule_tid_send(qp);
        goto ack_done;

ack_op_err:
        status = IB_WC_LOC_QP_OP_ERR;
ack_err:
        rvt_error_qp(qp, status);
ack_done:
        if (fecn)
                qp->s_flags |= RVT_S_ECN;
        spin_unlock_irqrestore(&qp->s_lock, flags);
}

bool hfi1_build_tid_rdma_packet(struct rvt_swqe *wqe,
                                struct ib_other_headers *ohdr,
                                u32 *bth1, u32 *bth2, u32 *len)
{
        struct tid_rdma_request *req = wqe_to_tid_req(wqe);
        struct tid_rdma_flow *flow = &req->flows[req->clear_tail];
        struct tid_rdma_params *remote;
        struct rvt_qp *qp = req->qp;
        struct hfi1_qp_priv *qpriv = qp->priv;
        u32 tidentry = flow->tid_entry[flow->tid_idx];
        u32 tidlen = EXP_TID_GET(tidentry, LEN) << PAGE_SHIFT;
        struct tid_rdma_write_data *wd = &ohdr->u.tid_rdma.w_data;
        u32 next_offset, om = KDETH_OM_LARGE;
        bool last_pkt;

        if (!tidlen) {
                hfi1_trdma_send_complete(qp, wqe, IB_WC_REM_INV_RD_REQ_ERR);
                rvt_error_qp(qp, IB_WC_REM_INV_RD_REQ_ERR);
        }

        *len = min_t(u32, qp->pmtu, tidlen - flow->tid_offset);
        flow->sent += *len;
        next_offset = flow->tid_offset + *len;
        last_pkt = (flow->tid_idx == (flow->tidcnt - 1) &&
                    next_offset >= tidlen) || (flow->sent >= flow->length);
        trace_hfi1_tid_entry_build_write_data(qp, flow->tid_idx, tidentry);
        trace_hfi1_tid_flow_build_write_data(qp, req->clear_tail, flow);

        rcu_read_lock();
        remote = rcu_dereference(qpriv->tid_rdma.remote);
        KDETH_RESET(wd->kdeth0, KVER, 0x1);
        KDETH_SET(wd->kdeth0, SH, !last_pkt);
        KDETH_SET(wd->kdeth0, INTR, !!(!last_pkt && remote->urg));
        KDETH_SET(wd->kdeth0, TIDCTRL, EXP_TID_GET(tidentry, CTRL));
        KDETH_SET(wd->kdeth0, TID, EXP_TID_GET(tidentry, IDX));
        KDETH_SET(wd->kdeth0, OM, om == KDETH_OM_LARGE);
        KDETH_SET(wd->kdeth0, OFFSET, flow->tid_offset / om);
        KDETH_RESET(wd->kdeth1, JKEY, remote->jkey);
        wd->verbs_qp = cpu_to_be32(qp->remote_qpn);
        rcu_read_unlock();

        *bth1 = flow->tid_qpn;
        *bth2 = mask_psn(((flow->flow_state.spsn + flow->pkt++) &
                         HFI1_KDETH_BTH_SEQ_MASK) |
                         (flow->flow_state.generation <<
                          HFI1_KDETH_BTH_SEQ_SHIFT));
        if (last_pkt) {
                /* PSNs are zero-based, so +1 to count number of packets */
                if (flow->flow_state.lpsn + 1 +
                    rvt_div_round_up_mtu(qp, req->seg_len) >
                    MAX_TID_FLOW_PSN)
                        req->state = TID_REQUEST_SYNC;
                *bth2 |= IB_BTH_REQ_ACK;
        }

        if (next_offset >= tidlen) {
                flow->tid_offset = 0;
                flow->tid_idx++;
        } else {
                flow->tid_offset = next_offset;
        }
        return last_pkt;
}

void hfi1_rc_rcv_tid_rdma_write_data(struct hfi1_packet *packet)
{
        struct rvt_qp *qp = packet->qp;
        struct hfi1_qp_priv *priv = qp->priv;
        struct hfi1_ctxtdata *rcd = priv->rcd;
        struct ib_other_headers *ohdr = packet->ohdr;
        struct rvt_ack_entry *e;
        struct tid_rdma_request *req;
        struct tid_rdma_flow *flow;
        struct hfi1_ibdev *dev = to_idev(qp->ibqp.device);
        unsigned long flags;
        u32 psn, next;
        u8 opcode;
        bool fecn;

        fecn = process_ecn(qp, packet);
        psn = mask_psn(be32_to_cpu(ohdr->bth[2]));
        opcode = (be32_to_cpu(ohdr->bth[0]) >> 24) & 0xff;

        /*
         * All error handling should be done by now. If we are here, the packet
         * is either good or been accepted by the error handler.
         */
        spin_lock_irqsave(&qp->s_lock, flags);
        e = &qp->s_ack_queue[priv->r_tid_tail];
        req = ack_to_tid_req(e);
        flow = &req->flows[req->clear_tail];
        if (cmp_psn(psn, full_flow_psn(flow, flow->flow_state.lpsn))) {
                update_r_next_psn_fecn(packet, priv, rcd, flow, fecn);

                if (cmp_psn(psn, flow->flow_state.r_next_psn))
                        goto send_nak;

                flow->flow_state.r_next_psn = mask_psn(psn + 1);
                /*
                 * Copy the payload to destination buffer if this packet is
                 * delivered as an eager packet due to RSM rule and FECN.
                 * The RSM rule selects FECN bit in BTH and SH bit in
                 * KDETH header and therefore will not match the last
                 * packet of each segment that has SH bit cleared.
                 */
                if (fecn && packet->etype == RHF_RCV_TYPE_EAGER) {
                        struct rvt_sge_state ss;
                        u32 len;
                        u32 tlen = packet->tlen;
                        u16 hdrsize = packet->hlen;
                        u8 pad = packet->pad;
                        u8 extra_bytes = pad + packet->extra_byte +
                                (SIZE_OF_CRC << 2);
                        u32 pmtu = qp->pmtu;

                        if (unlikely(tlen != (hdrsize + pmtu + extra_bytes)))
                                goto send_nak;
                        len = req->comp_seg * req->seg_len;
                        len += delta_psn(psn,
                                full_flow_psn(flow, flow->flow_state.spsn)) *
                                pmtu;
                        if (unlikely(req->total_len - len < pmtu))
                                goto send_nak;

                        /*
                         * The e->rdma_sge field is set when TID RDMA WRITE REQ
                         * is first received and is never modified thereafter.
                         */
                        ss.sge = e->rdma_sge;
                        ss.sg_list = NULL;
                        ss.num_sge = 1;
                        ss.total_len = req->total_len;
                        rvt_skip_sge(&ss, len, false);
                        rvt_copy_sge(qp, &ss, packet->payload, pmtu, false,
                                     false);
                        /* Raise the sw sequence check flag for next packet */
                        priv->r_next_psn_kdeth = mask_psn(psn + 1);
                        priv->s_flags |= HFI1_R_TID_SW_PSN;
                }
                goto exit;
        }
        flow->flow_state.r_next_psn = mask_psn(psn + 1);
        hfi1_kern_exp_rcv_clear(req);
        priv->alloc_w_segs--;
        rcd->flows[flow->idx].psn = psn & HFI1_KDETH_BTH_SEQ_MASK;
        req->comp_seg++;
        priv->s_nak_state = 0;

        /*
         * Release the flow if one of the following conditions has been met:
         *  - The request has reached a sync point AND all outstanding
         *    segments have been completed, or
         *  - The entire request is complete and there are no more requests
         *    (of any kind) in the queue.
         */
        trace_hfi1_rsp_rcv_tid_write_data(qp, psn);
        trace_hfi1_tid_req_rcv_write_data(qp, 0, e->opcode, e->psn, e->lpsn,
                                          req);
        trace_hfi1_tid_write_rsp_rcv_data(qp);
        validate_r_tid_ack(priv);

        if (opcode == TID_OP(WRITE_DATA_LAST)) {
                release_rdma_sge_mr(e);
                for (next = priv->r_tid_tail + 1; ; next++) {
                        if (next > rvt_size_atomic(&dev->rdi))
                                next = 0;
                        if (next == priv->r_tid_head)
                                break;
                        e = &qp->s_ack_queue[next];
                        if (e->opcode == TID_OP(WRITE_REQ))
                                break;
                }
                priv->r_tid_tail = next;
                if (++qp->s_acked_ack_queue > rvt_size_atomic(&dev->rdi))
                        qp->s_acked_ack_queue = 0;
        }

        hfi1_tid_write_alloc_resources(qp, true);

        /*
         * If we need to generate more responses, schedule the
         * send engine.
         */
        if (req->cur_seg < req->total_segs ||
            qp->s_tail_ack_queue != qp->r_head_ack_queue) {
                qp->s_flags |= RVT_S_RESP_PENDING;
                hfi1_schedule_send(qp);
        }

        priv->pending_tid_w_segs--;
        if (priv->s_flags & HFI1_R_TID_RSC_TIMER) {
                if (priv->pending_tid_w_segs)
                        hfi1_mod_tid_reap_timer(req->qp);
                else
                        hfi1_stop_tid_reap_timer(req->qp);
        }

done:
        tid_rdma_schedule_ack(qp);
exit:
        priv->r_next_psn_kdeth = flow->flow_state.r_next_psn;
        if (fecn)
                qp->s_flags |= RVT_S_ECN;
        spin_unlock_irqrestore(&qp->s_lock, flags);
        return;

send_nak:
        if (!priv->s_nak_state) {
                priv->s_nak_state = IB_NAK_PSN_ERROR;
                priv->s_nak_psn = flow->flow_state.r_next_psn;
                tid_rdma_trigger_ack(qp);
        }
        goto done;
}

static bool hfi1_tid_rdma_is_resync_psn(u32 psn)
{
        return (bool)((psn & HFI1_KDETH_BTH_SEQ_MASK) ==
                      HFI1_KDETH_BTH_SEQ_MASK);
}

u32 hfi1_build_tid_rdma_write_ack(struct rvt_qp *qp, struct rvt_ack_entry *e,
                                  struct ib_other_headers *ohdr, u16 iflow,
                                  u32 *bth1, u32 *bth2)
{
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct tid_flow_state *fs = &qpriv->flow_state;
        struct tid_rdma_request *req = ack_to_tid_req(e);
        struct tid_rdma_flow *flow = &req->flows[iflow];
        struct tid_rdma_params *remote;

        rcu_read_lock();
        remote = rcu_dereference(qpriv->tid_rdma.remote);
        KDETH_RESET(ohdr->u.tid_rdma.ack.kdeth1, JKEY, remote->jkey);
        ohdr->u.tid_rdma.ack.verbs_qp = cpu_to_be32(qp->remote_qpn);
        *bth1 = remote->qp;
        rcu_read_unlock();

        if (qpriv->resync) {
                *bth2 = mask_psn((fs->generation <<
                                  HFI1_KDETH_BTH_SEQ_SHIFT) - 1);
                ohdr->u.tid_rdma.ack.aeth = rvt_compute_aeth(qp);
        } else if (qpriv->s_nak_state) {
                *bth2 = mask_psn(qpriv->s_nak_psn);
                ohdr->u.tid_rdma.ack.aeth =
                        cpu_to_be32((qp->r_msn & IB_MSN_MASK) |
                                    (qpriv->s_nak_state <<
                                     IB_AETH_CREDIT_SHIFT));
        } else {
                *bth2 = full_flow_psn(flow, flow->flow_state.lpsn);
                ohdr->u.tid_rdma.ack.aeth = rvt_compute_aeth(qp);
        }
        KDETH_RESET(ohdr->u.tid_rdma.ack.kdeth0, KVER, 0x1);
        ohdr->u.tid_rdma.ack.tid_flow_qp =
                cpu_to_be32(qpriv->tid_rdma.local.qp |
                            ((flow->idx & TID_RDMA_DESTQP_FLOW_MASK) <<
                             TID_RDMA_DESTQP_FLOW_SHIFT) |
                            qpriv->rcd->ctxt);

        ohdr->u.tid_rdma.ack.tid_flow_psn = 0;
        ohdr->u.tid_rdma.ack.verbs_psn =
                cpu_to_be32(flow->flow_state.resp_ib_psn);

        if (qpriv->resync) {
                /*
                 * If the PSN before the current expect KDETH PSN is the
                 * RESYNC PSN, then we never received a good TID RDMA WRITE
                 * DATA packet after a previous RESYNC.
                 * In this case, the next expected KDETH PSN stays the same.
                 */
                if (hfi1_tid_rdma_is_resync_psn(qpriv->r_next_psn_kdeth - 1)) {
                        ohdr->u.tid_rdma.ack.tid_flow_psn =
                                cpu_to_be32(qpriv->r_next_psn_kdeth_save);
                } else {
                        /*
                         * Because the KDETH PSNs jump during a RESYNC, it's
                         * not possible to infer (or compute) the previous value
                         * of r_next_psn_kdeth in the case of back-to-back
                         * RESYNC packets. Therefore, we save it.
                         */
                        qpriv->r_next_psn_kdeth_save =
                                qpriv->r_next_psn_kdeth - 1;
                        ohdr->u.tid_rdma.ack.tid_flow_psn =
                                cpu_to_be32(qpriv->r_next_psn_kdeth_save);
                        qpriv->r_next_psn_kdeth = mask_psn(*bth2 + 1);
                }
                qpriv->resync = false;
        }

        return sizeof(ohdr->u.tid_rdma.ack) / sizeof(u32);
}

void hfi1_rc_rcv_tid_rdma_ack(struct hfi1_packet *packet)
{
        struct ib_other_headers *ohdr = packet->ohdr;
        struct rvt_qp *qp = packet->qp;
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct rvt_swqe *wqe;
        struct tid_rdma_request *req;
        struct tid_rdma_flow *flow;
        u32 aeth, psn, req_psn, ack_psn, flpsn, resync_psn, ack_kpsn;
        unsigned long flags;
        u16 fidx;

        trace_hfi1_tid_write_sender_rcv_tid_ack(qp, 0);
        process_ecn(qp, packet);
        psn = mask_psn(be32_to_cpu(ohdr->bth[2]));
        aeth = be32_to_cpu(ohdr->u.tid_rdma.ack.aeth);
        req_psn = mask_psn(be32_to_cpu(ohdr->u.tid_rdma.ack.verbs_psn));
        resync_psn = mask_psn(be32_to_cpu(ohdr->u.tid_rdma.ack.tid_flow_psn));

        spin_lock_irqsave(&qp->s_lock, flags);
        trace_hfi1_rcv_tid_ack(qp, aeth, psn, req_psn, resync_psn);

        /* If we are waiting for an ACK to RESYNC, drop any other packets */
        if ((qp->s_flags & HFI1_S_WAIT_HALT) &&
            cmp_psn(psn, qpriv->s_resync_psn))
                goto ack_op_err;

        ack_psn = req_psn;
        if (hfi1_tid_rdma_is_resync_psn(psn))
                ack_kpsn = resync_psn;
        else
                ack_kpsn = psn;
        if (aeth >> 29) {
                ack_psn--;
                ack_kpsn--;
        }

        if (unlikely(qp->s_acked == qp->s_tail))
                goto ack_op_err;

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

        if (wqe->wr.opcode != IB_WR_TID_RDMA_WRITE)
                goto ack_op_err;

        req = wqe_to_tid_req(wqe);
        trace_hfi1_tid_req_rcv_tid_ack(qp, 0, wqe->wr.opcode, wqe->psn,
                                       wqe->lpsn, req);
        flow = &req->flows[req->acked_tail];
        trace_hfi1_tid_flow_rcv_tid_ack(qp, req->acked_tail, flow);

        /* Drop stale ACK/NAK */
        if (cmp_psn(psn, full_flow_psn(flow, flow->flow_state.spsn)) < 0 ||
            cmp_psn(req_psn, flow->flow_state.resp_ib_psn) < 0)
                goto ack_op_err;

        while (cmp_psn(ack_kpsn,
                       full_flow_psn(flow, flow->flow_state.lpsn)) >= 0 &&
               req->ack_seg < req->cur_seg) {
                req->ack_seg++;
                /* advance acked segment pointer */
                req->acked_tail = CIRC_NEXT(req->acked_tail, MAX_FLOWS);
                req->r_last_acked = flow->flow_state.resp_ib_psn;
                trace_hfi1_tid_req_rcv_tid_ack(qp, 0, wqe->wr.opcode, wqe->psn,
                                               wqe->lpsn, req);
                if (req->ack_seg == req->total_segs) {
                        req->state = TID_REQUEST_COMPLETE;
                        wqe = do_rc_completion(qp, wqe,
                                               to_iport(qp->ibqp.device,
                                                        qp->port_num));
                        trace_hfi1_sender_rcv_tid_ack(qp);
                        atomic_dec(&qpriv->n_tid_requests);
                        if (qp->s_acked == qp->s_tail)
                                break;
                        if (wqe->wr.opcode != IB_WR_TID_RDMA_WRITE)
                                break;
                        req = wqe_to_tid_req(wqe);
                }
                flow = &req->flows[req->acked_tail];
                trace_hfi1_tid_flow_rcv_tid_ack(qp, req->acked_tail, flow);
        }

        trace_hfi1_tid_req_rcv_tid_ack(qp, 0, wqe->wr.opcode, wqe->psn,
                                       wqe->lpsn, req);
        switch (aeth >> 29) {
        case 0:         /* ACK */
                if (qpriv->s_flags & RVT_S_WAIT_ACK)
                        qpriv->s_flags &= ~RVT_S_WAIT_ACK;
                if (!hfi1_tid_rdma_is_resync_psn(psn)) {
                        /* Check if there is any pending TID ACK */
                        if (wqe->wr.opcode == IB_WR_TID_RDMA_WRITE &&
                            req->ack_seg < req->cur_seg)
                                hfi1_mod_tid_retry_timer(qp);
                        else
                                hfi1_stop_tid_retry_timer(qp);
                        hfi1_schedule_send(qp);
                } else {
                        u32 spsn, fpsn, last_acked, generation;
                        struct tid_rdma_request *rptr;

                        /* ACK(RESYNC) */
                        hfi1_stop_tid_retry_timer(qp);
                        /* Allow new requests (see hfi1_make_tid_rdma_pkt) */
                        qp->s_flags &= ~HFI1_S_WAIT_HALT;
                        /*
                         * Clear RVT_S_SEND_ONE flag in case that the TID RDMA
                         * ACK is received after the TID retry timer is fired
                         * again. In this case, do not send any more TID
                         * RESYNC request or wait for any more TID ACK packet.
                         */
                        qpriv->s_flags &= ~RVT_S_SEND_ONE;
                        hfi1_schedule_send(qp);

                        if ((qp->s_acked == qpriv->s_tid_tail &&
                             req->ack_seg == req->total_segs) ||
                            qp->s_acked == qp->s_tail) {
                                qpriv->s_state = TID_OP(WRITE_DATA_LAST);
                                goto done;
                        }

                        if (req->ack_seg == req->comp_seg) {
                                qpriv->s_state = TID_OP(WRITE_DATA);
                                goto done;
                        }

                        /*
                         * The PSN to start with is the next PSN after the
                         * RESYNC PSN.
                         */
                        psn = mask_psn(psn + 1);
                        generation = psn >> HFI1_KDETH_BTH_SEQ_SHIFT;
                        spsn = 0;

                        /*
                         * Update to the correct WQE when we get an ACK(RESYNC)
                         * in the middle of a request.
                         */
                        if (delta_psn(ack_psn, wqe->lpsn))
                                wqe = rvt_get_swqe_ptr(qp, qp->s_acked);
                        req = wqe_to_tid_req(wqe);
                        flow = &req->flows[req->acked_tail];
                        /*
                         * RESYNC re-numbers the PSN ranges of all remaining
                         * segments. Also, PSN's start from 0 in the middle of a
                         * segment and the first segment size is less than the
                         * default number of packets. flow->resync_npkts is used
                         * to track the number of packets from the start of the
                         * real segment to the point of 0 PSN after the RESYNC
                         * in order to later correctly rewind the SGE.
                         */
                        fpsn = full_flow_psn(flow, flow->flow_state.spsn);
                        req->r_ack_psn = psn;
                        /*
                         * If resync_psn points to the last flow PSN for a
                         * segment and the new segment (likely from a new
                         * request) starts with a new generation number, we
                         * need to adjust resync_psn accordingly.
                         */
                        if (flow->flow_state.generation !=
                            (resync_psn >> HFI1_KDETH_BTH_SEQ_SHIFT))
                                resync_psn = mask_psn(fpsn - 1);
                        flow->resync_npkts +=
                                delta_psn(mask_psn(resync_psn + 1), fpsn);
                        /*
                         * Renumber all packet sequence number ranges
                         * based on the new generation.
                         */
                        last_acked = qp->s_acked;
                        rptr = req;
                        while (1) {
                                /* start from last acked segment */
                                for (fidx = rptr->acked_tail;
                                     CIRC_CNT(rptr->setup_head, fidx,
                                              MAX_FLOWS);
                                     fidx = CIRC_NEXT(fidx, MAX_FLOWS)) {
                                        u32 lpsn;
                                        u32 gen;

                                        flow = &rptr->flows[fidx];
                                        gen = flow->flow_state.generation;
                                        if (WARN_ON(gen == generation &&
                                                    flow->flow_state.spsn !=
                                                     spsn))
                                                continue;
                                        lpsn = flow->flow_state.lpsn;
                                        lpsn = full_flow_psn(flow, lpsn);
                                        flow->npkts =
                                                delta_psn(lpsn,
                                                          mask_psn(resync_psn)
                                                          );
                                        flow->flow_state.generation =
                                                generation;
                                        flow->flow_state.spsn = spsn;
                                        flow->flow_state.lpsn =
                                                flow->flow_state.spsn +
                                                flow->npkts - 1;
                                        flow->pkt = 0;
                                        spsn += flow->npkts;
                                        resync_psn += flow->npkts;
                                        trace_hfi1_tid_flow_rcv_tid_ack(qp,
                                                                        fidx,
                                                                        flow);
                                }
                                if (++last_acked == qpriv->s_tid_cur + 1)
                                        break;
                                if (last_acked == qp->s_size)
                                        last_acked = 0;
                                wqe = rvt_get_swqe_ptr(qp, last_acked);
                                rptr = wqe_to_tid_req(wqe);
                        }
                        req->cur_seg = req->ack_seg;
                        qpriv->s_tid_tail = qp->s_acked;
                        qpriv->s_state = TID_OP(WRITE_REQ);
                        hfi1_schedule_tid_send(qp);
                }
done:
                qpriv->s_retry = qp->s_retry_cnt;
                break;

        case 3:         /* NAK */
                hfi1_stop_tid_retry_timer(qp);
                switch ((aeth >> IB_AETH_CREDIT_SHIFT) &
                        IB_AETH_CREDIT_MASK) {
                case 0: /* PSN sequence error */
                        if (!req->flows)
                                break;
                        flow = &req->flows[req->acked_tail];
                        flpsn = full_flow_psn(flow, flow->flow_state.lpsn);
                        if (cmp_psn(psn, flpsn) > 0)
                                break;
                        trace_hfi1_tid_flow_rcv_tid_ack(qp, req->acked_tail,
                                                        flow);
                        req->r_ack_psn = mask_psn(be32_to_cpu(ohdr->bth[2]));
                        req->cur_seg = req->ack_seg;
                        qpriv->s_tid_tail = qp->s_acked;
                        qpriv->s_state = TID_OP(WRITE_REQ);
                        qpriv->s_retry = qp->s_retry_cnt;
                        hfi1_schedule_tid_send(qp);
                        break;

                default:
                        break;
                }
                break;

        default:
                break;
        }

ack_op_err:
        spin_unlock_irqrestore(&qp->s_lock, flags);
}

void hfi1_add_tid_retry_timer(struct rvt_qp *qp)
{
        struct hfi1_qp_priv *priv = qp->priv;
        struct ib_qp *ibqp = &qp->ibqp;
        struct rvt_dev_info *rdi = ib_to_rvt(ibqp->device);

        lockdep_assert_held(&qp->s_lock);
        if (!(priv->s_flags & HFI1_S_TID_RETRY_TIMER)) {
                priv->s_flags |= HFI1_S_TID_RETRY_TIMER;
                priv->s_tid_retry_timer.expires = jiffies +
                        priv->tid_retry_timeout_jiffies + rdi->busy_jiffies;
                add_timer(&priv->s_tid_retry_timer);
        }
}

static void hfi1_mod_tid_retry_timer(struct rvt_qp *qp)
{
        struct hfi1_qp_priv *priv = qp->priv;
        struct ib_qp *ibqp = &qp->ibqp;
        struct rvt_dev_info *rdi = ib_to_rvt(ibqp->device);

        lockdep_assert_held(&qp->s_lock);
        priv->s_flags |= HFI1_S_TID_RETRY_TIMER;
        mod_timer(&priv->s_tid_retry_timer, jiffies +
                  priv->tid_retry_timeout_jiffies + rdi->busy_jiffies);
}

static int hfi1_stop_tid_retry_timer(struct rvt_qp *qp)
{
        struct hfi1_qp_priv *priv = qp->priv;
        int rval = 0;

        lockdep_assert_held(&qp->s_lock);
        if (priv->s_flags & HFI1_S_TID_RETRY_TIMER) {
                rval = del_timer(&priv->s_tid_retry_timer);
                priv->s_flags &= ~HFI1_S_TID_RETRY_TIMER;
        }
        return rval;
}

void hfi1_del_tid_retry_timer(struct rvt_qp *qp)
{
        struct hfi1_qp_priv *priv = qp->priv;

        del_timer_sync(&priv->s_tid_retry_timer);
        priv->s_flags &= ~HFI1_S_TID_RETRY_TIMER;
}

static void hfi1_tid_retry_timeout(struct timer_list *t)
{
        struct hfi1_qp_priv *priv = from_timer(priv, t, s_tid_retry_timer);
        struct rvt_qp *qp = priv->owner;
        struct rvt_swqe *wqe;
        unsigned long flags;
        struct tid_rdma_request *req;

        spin_lock_irqsave(&qp->r_lock, flags);
        spin_lock(&qp->s_lock);
        trace_hfi1_tid_write_sender_retry_timeout(qp, 0);
        if (priv->s_flags & HFI1_S_TID_RETRY_TIMER) {
                hfi1_stop_tid_retry_timer(qp);
                if (!priv->s_retry) {
                        trace_hfi1_msg_tid_retry_timeout(/* msg */
                                qp,
                                "Exhausted retries. Tid retry timeout = ",
                                (u64)priv->tid_retry_timeout_jiffies);

                        wqe = rvt_get_swqe_ptr(qp, qp->s_acked);
                        hfi1_trdma_send_complete(qp, wqe, IB_WC_RETRY_EXC_ERR);
                        rvt_error_qp(qp, IB_WC_WR_FLUSH_ERR);
                } else {
                        wqe = rvt_get_swqe_ptr(qp, qp->s_acked);
                        req = wqe_to_tid_req(wqe);
                        trace_hfi1_tid_req_tid_retry_timeout(/* req */
                           qp, 0, wqe->wr.opcode, wqe->psn, wqe->lpsn, req);

                        priv->s_flags &= ~RVT_S_WAIT_ACK;
                        /* Only send one packet (the RESYNC) */
                        priv->s_flags |= RVT_S_SEND_ONE;
                        /*
                         * No additional request shall be made by this QP until
                         * the RESYNC has been complete.
                         */
                        qp->s_flags |= HFI1_S_WAIT_HALT;
                        priv->s_state = TID_OP(RESYNC);
                        priv->s_retry--;
                        hfi1_schedule_tid_send(qp);
                }
        }
        spin_unlock(&qp->s_lock);
        spin_unlock_irqrestore(&qp->r_lock, flags);
}

u32 hfi1_build_tid_rdma_resync(struct rvt_qp *qp, struct rvt_swqe *wqe,
                               struct ib_other_headers *ohdr, u32 *bth1,
                               u32 *bth2, u16 fidx)
{
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct tid_rdma_params *remote;
        struct tid_rdma_request *req = wqe_to_tid_req(wqe);
        struct tid_rdma_flow *flow = &req->flows[fidx];
        u32 generation;

        rcu_read_lock();
        remote = rcu_dereference(qpriv->tid_rdma.remote);
        KDETH_RESET(ohdr->u.tid_rdma.ack.kdeth1, JKEY, remote->jkey);
        ohdr->u.tid_rdma.ack.verbs_qp = cpu_to_be32(qp->remote_qpn);
        *bth1 = remote->qp;
        rcu_read_unlock();

        generation = kern_flow_generation_next(flow->flow_state.generation);
        *bth2 = mask_psn((generation << HFI1_KDETH_BTH_SEQ_SHIFT) - 1);
        qpriv->s_resync_psn = *bth2;
        *bth2 |= IB_BTH_REQ_ACK;
        KDETH_RESET(ohdr->u.tid_rdma.ack.kdeth0, KVER, 0x1);

        return sizeof(ohdr->u.tid_rdma.resync) / sizeof(u32);
}

void hfi1_rc_rcv_tid_rdma_resync(struct hfi1_packet *packet)
{
        struct ib_other_headers *ohdr = packet->ohdr;
        struct rvt_qp *qp = packet->qp;
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct hfi1_ctxtdata *rcd = qpriv->rcd;
        struct hfi1_ibdev *dev = to_idev(qp->ibqp.device);
        struct rvt_ack_entry *e;
        struct tid_rdma_request *req;
        struct tid_rdma_flow *flow;
        struct tid_flow_state *fs = &qpriv->flow_state;
        u32 psn, generation, idx, gen_next;
        bool fecn;
        unsigned long flags;

        fecn = process_ecn(qp, packet);
        psn = mask_psn(be32_to_cpu(ohdr->bth[2]));

        generation = mask_psn(psn + 1) >> HFI1_KDETH_BTH_SEQ_SHIFT;
        spin_lock_irqsave(&qp->s_lock, flags);

        gen_next = (fs->generation == KERN_GENERATION_RESERVED) ?
                generation : kern_flow_generation_next(fs->generation);
        /*
         * RESYNC packet contains the "next" generation and can only be
         * from the current or previous generations
         */
        if (generation != mask_generation(gen_next - 1) &&
            generation != gen_next)
                goto bail;
        /* Already processing a resync */
        if (qpriv->resync)
                goto bail;

        spin_lock(&rcd->exp_lock);
        if (fs->index >= RXE_NUM_TID_FLOWS) {
                /*
                 * If we don't have a flow, save the generation so it can be
                 * applied when a new flow is allocated
                 */
                fs->generation = generation;
        } else {
                /* Reprogram the QP flow with new generation */
                rcd->flows[fs->index].generation = generation;
                fs->generation = kern_setup_hw_flow(rcd, fs->index);
        }
        fs->psn = 0;
        /*
         * Disable SW PSN checking since a RESYNC is equivalent to a
         * sync point and the flow has/will be reprogrammed
         */
        qpriv->s_flags &= ~HFI1_R_TID_SW_PSN;
        trace_hfi1_tid_write_rsp_rcv_resync(qp);

        /*
         * Reset all TID flow information with the new generation.
         * This is done for all requests and segments after the
         * last received segment
         */
        for (idx = qpriv->r_tid_tail; ; idx++) {
                u16 flow_idx;

                if (idx > rvt_size_atomic(&dev->rdi))
                        idx = 0;
                e = &qp->s_ack_queue[idx];
                if (e->opcode == TID_OP(WRITE_REQ)) {
                        req = ack_to_tid_req(e);
                        trace_hfi1_tid_req_rcv_resync(qp, 0, e->opcode, e->psn,
                                                      e->lpsn, req);

                        /* start from last unacked segment */
                        for (flow_idx = req->clear_tail;
                             CIRC_CNT(req->setup_head, flow_idx,
                                      MAX_FLOWS);
                             flow_idx = CIRC_NEXT(flow_idx, MAX_FLOWS)) {
                                u32 lpsn;
                                u32 next;

                                flow = &req->flows[flow_idx];
                                lpsn = full_flow_psn(flow,
                                                     flow->flow_state.lpsn);
                                next = flow->flow_state.r_next_psn;
                                flow->npkts = delta_psn(lpsn, next - 1);
                                flow->flow_state.generation = fs->generation;
                                flow->flow_state.spsn = fs->psn;
                                flow->flow_state.lpsn =
                                        flow->flow_state.spsn + flow->npkts - 1;
                                flow->flow_state.r_next_psn =
                                        full_flow_psn(flow,
                                                      flow->flow_state.spsn);
                                fs->psn += flow->npkts;
                                trace_hfi1_tid_flow_rcv_resync(qp, flow_idx,
                                                               flow);
                        }
                }
                if (idx == qp->s_tail_ack_queue)
                        break;
        }

        spin_unlock(&rcd->exp_lock);
        qpriv->resync = true;
        /* RESYNC request always gets a TID RDMA ACK. */
        qpriv->s_nak_state = 0;
        tid_rdma_trigger_ack(qp);
bail:
        if (fecn)
                qp->s_flags |= RVT_S_ECN;
        spin_unlock_irqrestore(&qp->s_lock, flags);
}

/*
 * Call this function when the last TID RDMA WRITE DATA packet for a request
 * is built.
 */
static void update_tid_tail(struct rvt_qp *qp)
        __must_hold(&qp->s_lock)
{
        struct hfi1_qp_priv *priv = qp->priv;
        u32 i;
        struct rvt_swqe *wqe;

        lockdep_assert_held(&qp->s_lock);
        /* Can't move beyond s_tid_cur */
        if (priv->s_tid_tail == priv->s_tid_cur)
                return;
        for (i = priv->s_tid_tail + 1; ; i++) {
                if (i == qp->s_size)
                        i = 0;

                if (i == priv->s_tid_cur)
                        break;
                wqe = rvt_get_swqe_ptr(qp, i);
                if (wqe->wr.opcode == IB_WR_TID_RDMA_WRITE)
                        break;
        }
        priv->s_tid_tail = i;
        priv->s_state = TID_OP(WRITE_RESP);
}

int hfi1_make_tid_rdma_pkt(struct rvt_qp *qp, struct hfi1_pkt_state *ps)
        __must_hold(&qp->s_lock)
{
        struct hfi1_qp_priv *priv = qp->priv;
        struct rvt_swqe *wqe;
        u32 bth1 = 0, bth2 = 0, hwords = 5, len, middle = 0;
        struct ib_other_headers *ohdr;
        struct rvt_sge_state *ss = &qp->s_sge;
        struct rvt_ack_entry *e = &qp->s_ack_queue[qp->s_tail_ack_queue];
        struct tid_rdma_request *req = ack_to_tid_req(e);
        bool last = false;
        u8 opcode = TID_OP(WRITE_DATA);

        lockdep_assert_held(&qp->s_lock);
        trace_hfi1_tid_write_sender_make_tid_pkt(qp, 0);
        /*
         * Prioritize the sending of the requests and responses over the
         * sending of the TID RDMA data packets.
         */
        if (((atomic_read(&priv->n_tid_requests) < HFI1_TID_RDMA_WRITE_CNT) &&
             atomic_read(&priv->n_requests) &&
             !(qp->s_flags & (RVT_S_BUSY | RVT_S_WAIT_ACK |
                             HFI1_S_ANY_WAIT_IO))) ||
            (e->opcode == TID_OP(WRITE_REQ) && req->cur_seg < req->alloc_seg &&
             !(qp->s_flags & (RVT_S_BUSY | HFI1_S_ANY_WAIT_IO)))) {
                struct iowait_work *iowork;

                iowork = iowait_get_ib_work(&priv->s_iowait);
                ps->s_txreq = get_waiting_verbs_txreq(iowork);
                if (ps->s_txreq || hfi1_make_rc_req(qp, ps)) {
                        priv->s_flags |= HFI1_S_TID_BUSY_SET;
                        return 1;
                }
        }

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

        ohdr = &ps->s_txreq->phdr.hdr.ibh.u.oth;

        if ((priv->s_flags & RVT_S_ACK_PENDING) &&
            make_tid_rdma_ack(qp, ohdr, ps))
                return 1;

        /*
         * Bail out if we can't send data.
         * Be reminded that this check must been done after the call to
         * make_tid_rdma_ack() because the responding QP could be in
         * RTR state where it can send TID RDMA ACK, not TID RDMA WRITE DATA.
         */
        if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_SEND_OK))
                goto bail;

        if (priv->s_flags & RVT_S_WAIT_ACK)
                goto bail;

        /* Check whether there is anything to do. */
        if (priv->s_tid_tail == HFI1_QP_WQE_INVALID)
                goto bail;
        wqe = rvt_get_swqe_ptr(qp, priv->s_tid_tail);
        req = wqe_to_tid_req(wqe);
        trace_hfi1_tid_req_make_tid_pkt(qp, 0, wqe->wr.opcode, wqe->psn,
                                        wqe->lpsn, req);
        switch (priv->s_state) {
        case TID_OP(WRITE_REQ):
        case TID_OP(WRITE_RESP):
                priv->tid_ss.sge = wqe->sg_list[0];
                priv->tid_ss.sg_list = wqe->sg_list + 1;
                priv->tid_ss.num_sge = wqe->wr.num_sge;
                priv->tid_ss.total_len = wqe->length;

                if (priv->s_state == TID_OP(WRITE_REQ))
                        hfi1_tid_rdma_restart_req(qp, wqe, &bth2);
                priv->s_state = TID_OP(WRITE_DATA);
                fallthrough;

        case TID_OP(WRITE_DATA):
                /*
                 * 1. Check whether TID RDMA WRITE RESP available.
                 * 2. If no:
                 *    2.1 If have more segments and no TID RDMA WRITE RESP,
                 *        set HFI1_S_WAIT_TID_RESP
                 *    2.2 Return indicating no progress made.
                 * 3. If yes:
                 *    3.1 Build TID RDMA WRITE DATA packet.
                 *    3.2 If last packet in segment:
                 *        3.2.1 Change KDETH header bits
                 *        3.2.2 Advance RESP pointers.
                 *    3.3 Return indicating progress made.
                 */
                trace_hfi1_sender_make_tid_pkt(qp);
                trace_hfi1_tid_write_sender_make_tid_pkt(qp, 0);
                wqe = rvt_get_swqe_ptr(qp, priv->s_tid_tail);
                req = wqe_to_tid_req(wqe);
                len = wqe->length;

                if (!req->comp_seg || req->cur_seg == req->comp_seg)
                        goto bail;

                trace_hfi1_tid_req_make_tid_pkt(qp, 0, wqe->wr.opcode,
                                                wqe->psn, wqe->lpsn, req);
                last = hfi1_build_tid_rdma_packet(wqe, ohdr, &bth1, &bth2,
                                                  &len);

                if (last) {
                        /* move pointer to next flow */
                        req->clear_tail = CIRC_NEXT(req->clear_tail,
                                                    MAX_FLOWS);
                        if (++req->cur_seg < req->total_segs) {
                                if (!CIRC_CNT(req->setup_head, req->clear_tail,
                                              MAX_FLOWS))
                                        qp->s_flags |= HFI1_S_WAIT_TID_RESP;
                        } else {
                                priv->s_state = TID_OP(WRITE_DATA_LAST);
                                opcode = TID_OP(WRITE_DATA_LAST);

                                /* Advance the s_tid_tail now */
                                update_tid_tail(qp);
                        }
                }
                hwords += sizeof(ohdr->u.tid_rdma.w_data) / sizeof(u32);
                ss = &priv->tid_ss;
                break;

        case TID_OP(RESYNC):
                trace_hfi1_sender_make_tid_pkt(qp);
                /* Use generation from the most recently received response */
                wqe = rvt_get_swqe_ptr(qp, priv->s_tid_cur);
                req = wqe_to_tid_req(wqe);
                /* If no responses for this WQE look at the previous one */
                if (!req->comp_seg) {
                        wqe = rvt_get_swqe_ptr(qp,
                                               (!priv->s_tid_cur ? qp->s_size :
                                                priv->s_tid_cur) - 1);
                        req = wqe_to_tid_req(wqe);
                }
                hwords += hfi1_build_tid_rdma_resync(qp, wqe, ohdr, &bth1,
                                                     &bth2,
                                                     CIRC_PREV(req->setup_head,
                                                               MAX_FLOWS));
                ss = NULL;
                len = 0;
                opcode = TID_OP(RESYNC);
                break;

        default:
                goto bail;
        }
        if (priv->s_flags & RVT_S_SEND_ONE) {
                priv->s_flags &= ~RVT_S_SEND_ONE;
                priv->s_flags |= RVT_S_WAIT_ACK;
                bth2 |= IB_BTH_REQ_ACK;
        }
        qp->s_len -= len;
        ps->s_txreq->hdr_dwords = hwords;
        ps->s_txreq->sde = priv->s_sde;
        ps->s_txreq->ss = ss;
        ps->s_txreq->s_cur_size = len;
        hfi1_make_ruc_header(qp, ohdr, (opcode << 24), bth1, bth2,
                             middle, ps);
        return 1;
bail:
        hfi1_put_txreq(ps->s_txreq);
bail_no_tx:
        ps->s_txreq = NULL;
        priv->s_flags &= ~RVT_S_BUSY;
        /*
         * If we didn't get a txreq, the QP will be woken up later to try
         * again, set the flags to the wake up which work item to wake
         * up.
         * (A better algorithm should be found to do this and generalize the
         * sleep/wakeup flags.)
         */
        iowait_set_flag(&priv->s_iowait, IOWAIT_PENDING_TID);
        return 0;
}

static int make_tid_rdma_ack(struct rvt_qp *qp,
                             struct ib_other_headers *ohdr,
                             struct hfi1_pkt_state *ps)
{
        struct rvt_ack_entry *e;
        struct hfi1_qp_priv *qpriv = qp->priv;
        struct hfi1_ibdev *dev = to_idev(qp->ibqp.device);
        u32 hwords, next;
        u32 len = 0;
        u32 bth1 = 0, bth2 = 0;
        int middle = 0;
        u16 flow;
        struct tid_rdma_request *req, *nreq;

        trace_hfi1_tid_write_rsp_make_tid_ack(qp);
        /* Don't send an ACK if we aren't supposed to. */
        if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK))
                goto bail;

        /* header size in 32-bit words LRH+BTH = (8+12)/4. */
        hwords = 5;

        e = &qp->s_ack_queue[qpriv->r_tid_ack];
        req = ack_to_tid_req(e);
        /*
         * In the RESYNC case, we are exactly one segment past the
         * previously sent ack or at the previously sent NAK. So to send
         * the resync ack, we go back one segment (which might be part of
         * the previous request) and let the do-while loop execute again.
         * The advantage of executing the do-while loop is that any data
         * received after the previous ack is automatically acked in the
         * RESYNC ack. It turns out that for the do-while loop we only need
         * to pull back qpriv->r_tid_ack, not the segment
         * indices/counters. The scheme works even if the previous request
         * was not a TID WRITE request.
         */
        if (qpriv->resync) {
                if (!req->ack_seg || req->ack_seg == req->total_segs)
                        qpriv->r_tid_ack = !qpriv->r_tid_ack ?
                                rvt_size_atomic(&dev->rdi) :
                                qpriv->r_tid_ack - 1;
                e = &qp->s_ack_queue[qpriv->r_tid_ack];
                req = ack_to_tid_req(e);
        }

        trace_hfi1_rsp_make_tid_ack(qp, e->psn);
        trace_hfi1_tid_req_make_tid_ack(qp, 0, e->opcode, e->psn, e->lpsn,
                                        req);
        /*
         * If we've sent all the ACKs that we can, we are done
         * until we get more segments...
         */
        if (!qpriv->s_nak_state && !qpriv->resync &&
            req->ack_seg == req->comp_seg)
                goto bail;

        do {
                /*
                 * To deal with coalesced ACKs, the acked_tail pointer
                 * into the flow array is used. The distance between it
                 * and the clear_tail is the number of flows that are
                 * being ACK'ed.
                 */
                req->ack_seg +=
                        /* Get up-to-date value */
                        CIRC_CNT(req->clear_tail, req->acked_tail,
                                 MAX_FLOWS);
                /* Advance acked index */
                req->acked_tail = req->clear_tail;

                /*
                 * req->clear_tail points to the segment currently being
                 * received. So, when sending an ACK, the previous
                 * segment is being ACK'ed.
                 */
                flow = CIRC_PREV(req->acked_tail, MAX_FLOWS);
                if (req->ack_seg != req->total_segs)
                        break;
                req->state = TID_REQUEST_COMPLETE;

                next = qpriv->r_tid_ack + 1;
                if (next > rvt_size_atomic(&dev->rdi))
                        next = 0;
                qpriv->r_tid_ack = next;
                if (qp->s_ack_queue[next].opcode != TID_OP(WRITE_REQ))
                        break;
                nreq = ack_to_tid_req(&qp->s_ack_queue[next]);
                if (!nreq->comp_seg || nreq->ack_seg == nreq->comp_seg)
                        break;

                /* Move to the next ack entry now */
                e = &qp->s_ack_queue[qpriv->r_tid_ack];
                req = ack_to_tid_req(e);
        } while (1);

        /*
         * At this point qpriv->r_tid_ack == qpriv->r_tid_tail but e and
         * req could be pointing at the previous ack queue entry
         */
        if (qpriv->s_nak_state ||
            (qpriv->resync &&
             !hfi1_tid_rdma_is_resync_psn(qpriv->r_next_psn_kdeth - 1) &&
             (cmp_psn(qpriv->r_next_psn_kdeth - 1,
                      full_flow_psn(&req->flows[flow],
                                    req->flows[flow].flow_state.lpsn)) > 0))) {
                /*
                 * A NAK will implicitly acknowledge all previous TID RDMA
                 * requests. Therefore, we NAK with the req->acked_tail
                 * segment for the request at qpriv->r_tid_ack (same at
                 * this point as the req->clear_tail segment for the
                 * qpriv->r_tid_tail request)
                 */
                e = &qp->s_ack_queue[qpriv->r_tid_ack];
                req = ack_to_tid_req(e);
                flow = req->acked_tail;
        } else if (req->ack_seg == req->total_segs &&
                   qpriv->s_flags & HFI1_R_TID_WAIT_INTERLCK)
                qpriv->s_flags &= ~HFI1_R_TID_WAIT_INTERLCK;

        trace_hfi1_tid_write_rsp_make_tid_ack(qp);
        trace_hfi1_tid_req_make_tid_ack(qp, 0, e->opcode, e->psn, e->lpsn,
                                        req);
        hwords += hfi1_build_tid_rdma_write_ack(qp, e, ohdr, flow, &bth1,
                                                &bth2);
        len = 0;
        qpriv->s_flags &= ~RVT_S_ACK_PENDING;
        ps->s_txreq->hdr_dwords = hwords;
        ps->s_txreq->sde = qpriv->s_sde;
        ps->s_txreq->s_cur_size = len;
        ps->s_txreq->ss = NULL;
        hfi1_make_ruc_header(qp, ohdr, (TID_OP(ACK) << 24), bth1, bth2, middle,
                             ps);
        ps->s_txreq->txreq.flags |= SDMA_TXREQ_F_VIP;
        return 1;
bail:
        /*
         * Ensure s_rdma_ack_cnt changes are committed prior to resetting
         * RVT_S_RESP_PENDING
         */
        smp_wmb();
        qpriv->s_flags &= ~RVT_S_ACK_PENDING;
        return 0;
}

static int hfi1_send_tid_ok(struct rvt_qp *qp)
{
        struct hfi1_qp_priv *priv = qp->priv;

        return !(priv->s_flags & RVT_S_BUSY ||
                 qp->s_flags & HFI1_S_ANY_WAIT_IO) &&
                (verbs_txreq_queued(iowait_get_tid_work(&priv->s_iowait)) ||
                 (priv->s_flags & RVT_S_RESP_PENDING) ||
                 !(qp->s_flags & HFI1_S_ANY_TID_WAIT_SEND));
}

void _hfi1_do_tid_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_tid_send(qp);
}

static void hfi1_do_tid_send(struct rvt_qp *qp)
{
        struct hfi1_pkt_state ps;
        struct hfi1_qp_priv *priv = qp->priv;

        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.wait = iowait_get_tid_work(&priv->s_iowait);
        ps.in_thread = false;
        ps.timeout_int = qp->timeout_jiffies / 8;

        trace_hfi1_rc_do_tid_send(qp, false);
        spin_lock_irqsave(&qp->s_lock, ps.flags);

        /* Return if we are already busy processing a work request. */
        if (!hfi1_send_tid_ok(qp)) {
                if (qp->s_flags & HFI1_S_ANY_WAIT_IO)
                        iowait_set_flag(&priv->s_iowait, IOWAIT_PENDING_TID);
                spin_unlock_irqrestore(&qp->s_lock, ps.flags);
                return;
        }

        priv->s_flags |= RVT_S_BUSY;

        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;
                                ps.wait = iowait_get_ib_work(&priv->s_iowait);
                        }
                        spin_unlock_irqrestore(&qp->s_lock, ps.flags);

                        /*
                         * If the packet cannot be sent now, return and
                         * the send tasklet will be woken up later.
                         */
                        if (hfi1_verbs_send(qp, &ps))
                                return;

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

                        spin_lock_irqsave(&qp->s_lock, ps.flags);
                        if (priv->s_flags & HFI1_S_TID_BUSY_SET) {
                                qp->s_flags &= ~RVT_S_BUSY;
                                priv->s_flags &= ~HFI1_S_TID_BUSY_SET;
                                ps.wait = iowait_get_tid_work(&priv->s_iowait);
                                if (iowait_flag_set(&priv->s_iowait,
                                                    IOWAIT_PENDING_IB))
                                        hfi1_schedule_send(qp);
                        }
                }
        } while (hfi1_make_tid_rdma_pkt(qp, &ps));
        iowait_starve_clear(ps.pkts_sent, &priv->s_iowait);
        spin_unlock_irqrestore(&qp->s_lock, ps.flags);
}

static bool _hfi1_schedule_tid_send(struct rvt_qp *qp)
{
        struct hfi1_qp_priv *priv = qp->priv;
        struct hfi1_ibport *ibp =
                to_iport(qp->ibqp.device, qp->port_num);
        struct hfi1_pportdata *ppd = ppd_from_ibp(ibp);
        struct hfi1_devdata *dd = ppd->dd;

        if ((dd->flags & HFI1_SHUTDOWN))
                return true;

        return iowait_tid_schedule(&priv->s_iowait, ppd->hfi1_wq,
                                   priv->s_sde ?
                                   priv->s_sde->cpu :
                                   cpumask_first(cpumask_of_node(dd->node)));
}

/**
 * hfi1_schedule_tid_send - schedule progress on TID RDMA state machine
 * @qp: the QP
 *
 * This schedules qp progress on the TID RDMA state machine. Caller
 * should hold the s_lock.
 * Unlike hfi1_schedule_send(), this cannot use hfi1_send_ok() because
 * the two state machines can step on each other with respect to the
 * RVT_S_BUSY flag.
 * Therefore, a modified test is used.
 *
 * Return: %true if the second leg is scheduled;
 *  %false if the second leg is not scheduled.
 */
bool hfi1_schedule_tid_send(struct rvt_qp *qp)
{
        lockdep_assert_held(&qp->s_lock);
        if (hfi1_send_tid_ok(qp)) {
                /*
                 * The following call returns true if the qp is not on the
                 * queue and false if the qp is already on the queue before
                 * this call. Either way, the qp will be on the queue when the
                 * call returns.
                 */
                _hfi1_schedule_tid_send(qp);
                return true;
        }
        if (qp->s_flags & HFI1_S_ANY_WAIT_IO)
                iowait_set_flag(&((struct hfi1_qp_priv *)qp->priv)->s_iowait,
                                IOWAIT_PENDING_TID);
        return false;
}

bool hfi1_tid_rdma_ack_interlock(struct rvt_qp *qp, struct rvt_ack_entry *e)
{
        struct rvt_ack_entry *prev;
        struct tid_rdma_request *req;
        struct hfi1_ibdev *dev = to_idev(qp->ibqp.device);
        struct hfi1_qp_priv *priv = qp->priv;
        u32 s_prev;

        s_prev = qp->s_tail_ack_queue == 0 ? rvt_size_atomic(&dev->rdi) :
                (qp->s_tail_ack_queue - 1);
        prev = &qp->s_ack_queue[s_prev];

        if ((e->opcode == TID_OP(READ_REQ) ||
             e->opcode == OP(RDMA_READ_REQUEST)) &&
            prev->opcode == TID_OP(WRITE_REQ)) {
                req = ack_to_tid_req(prev);
                if (req->ack_seg != req->total_segs) {
                        priv->s_flags |= HFI1_R_TID_WAIT_INTERLCK;
                        return true;
                }
        }
        return false;
}

static u32 read_r_next_psn(struct hfi1_devdata *dd, u8 ctxt, u8 fidx)
{
        u64 reg;

        /*
         * The only sane way to get the amount of
         * progress is to read the HW flow state.
         */
        reg = read_uctxt_csr(dd, ctxt, RCV_TID_FLOW_TABLE + (8 * fidx));
        return mask_psn(reg);
}

static void tid_rdma_rcv_err(struct hfi1_packet *packet,
                             struct ib_other_headers *ohdr,
                             struct rvt_qp *qp, u32 psn, int diff, bool fecn)
{
        unsigned long flags;

        tid_rdma_rcv_error(packet, ohdr, qp, psn, diff);
        if (fecn) {
                spin_lock_irqsave(&qp->s_lock, flags);
                qp->s_flags |= RVT_S_ECN;
                spin_unlock_irqrestore(&qp->s_lock, flags);
        }
}

static void update_r_next_psn_fecn(struct hfi1_packet *packet,
                                   struct hfi1_qp_priv *priv,
                                   struct hfi1_ctxtdata *rcd,
                                   struct tid_rdma_flow *flow,
                                   bool fecn)
{
        /*
         * If a start/middle packet is delivered here due to
         * RSM rule and FECN, we need to update the r_next_psn.
         */
        if (fecn && packet->etype == RHF_RCV_TYPE_EAGER &&
            !(priv->s_flags & HFI1_R_TID_SW_PSN)) {
                struct hfi1_devdata *dd = rcd->dd;

                flow->flow_state.r_next_psn =
                        read_r_next_psn(dd, rcd->ctxt, flow->idx);
        }
}