/**
* Copyright (c) NVIDIA CORPORATION & AFFILIATES, 2001-2014. ALL RIGHTS RESERVED.
* Copyright (c) UT-Battelle, LLC. 2015. ALL RIGHTS RESERVED.
* Copyright (C) Huawei Technologies Co., Ltd. 2021.  ALL RIGHTS RESERVED.
*
* See file LICENSE for terms.
*/

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include "rc_ep.h"
#include "rc_iface.h"

#include <uct/ib/base/ib_verbs.h>
#include <ucs/debug/memtrack_int.h>
#include <ucs/debug/log.h>
#include <ucs/vfs/base/vfs_cb.h>
#include <ucs/vfs/base/vfs_obj.h>
#include <ucs/type/class.h>
#include <endian.h>

#ifdef ENABLE_STATS
static ucs_stats_class_t uct_rc_fc_stats_class = {
    .name          = "rc_fc",
    .num_counters  = UCT_RC_FC_STAT_LAST,
    .class_id      = UCS_STATS_CLASS_ID_INVALID,
    .counter_names = {
        [UCT_RC_FC_STAT_NO_CRED]            = "no_cred",
        [UCT_RC_FC_STAT_TX_GRANT]           = "tx_grant",
        [UCT_RC_FC_STAT_TX_PURE_GRANT]      = "tx_pure_grant",
        [UCT_RC_FC_STAT_TX_SOFT_REQ]        = "tx_soft_req",
        [UCT_RC_FC_STAT_TX_HARD_REQ]        = "tx_hard_req",
        [UCT_RC_FC_STAT_RX_GRANT]           = "rx_grant",
        [UCT_RC_FC_STAT_RX_PURE_GRANT]      = "rx_pure_grant",
        [UCT_RC_FC_STAT_RX_SOFT_REQ]        = "rx_soft_req",
        [UCT_RC_FC_STAT_RX_HARD_REQ]        = "rx_hard_req",
        [UCT_RC_FC_STAT_FC_WND]             = "fc_wnd"
    }
};

static ucs_stats_class_t uct_rc_txqp_stats_class = {
    .name          = "rc_txqp",
    .num_counters  = UCT_RC_TXQP_STAT_LAST,
    .class_id      = UCS_STATS_CLASS_ID_INVALID,
    .counter_names = {
        [UCT_RC_TXQP_STAT_QP_FULL]          = "qp_full",
        [UCT_RC_TXQP_STAT_SIGNAL]           = "signal"
    }
};
#endif

static ucs_status_t uct_rc_ep_check_progress(uct_pending_req_t *self);

ucs_status_t uct_rc_txqp_init(uct_rc_txqp_t *txqp, uct_rc_iface_t *iface,
                              uint32_t qp_num
                              UCS_STATS_ARG(ucs_stats_node_t* stats_parent))
{
    txqp->unsignaled = 0;
    txqp->available  = 0;
    ucs_queue_head_init(&txqp->outstanding);

    return UCS_STATS_NODE_ALLOC(&txqp->stats, &uct_rc_txqp_stats_class,
                                stats_parent, "-0x%x", qp_num);
}

void uct_rc_txqp_cleanup(uct_rc_iface_t *iface, uct_rc_txqp_t *txqp)
{
    ucs_assert(ucs_queue_is_empty(&txqp->outstanding));
    UCS_STATS_NODE_FREE(txqp->stats);
}

void uct_rc_txqp_vfs_populate(uct_rc_txqp_t *txqp, void *parent_obj)
{
    ucs_vfs_obj_add_ro_file(parent_obj, ucs_vfs_show_primitive,
                            &txqp->unsignaled, UCS_VFS_TYPE_U16, "unsignaled");
    ucs_vfs_obj_add_ro_file(parent_obj, ucs_vfs_show_primitive,
                            &txqp->available, UCS_VFS_TYPE_I16, "available");
}

ucs_status_t uct_rc_fc_init(uct_rc_fc_t *fc, uct_rc_iface_t *iface
                            UCS_STATS_ARG(ucs_stats_node_t* stats_parent))
{
    ucs_status_t status;

    fc->fc_wnd = iface->config.fc_wnd_size;

    if (!iface->config.fc_enabled) {
        UCS_STATS_NODE_RESET(&fc->stats);
        return UCS_OK;
    }

    status = UCS_STATS_NODE_ALLOC(&fc->stats, &uct_rc_fc_stats_class,
                                  stats_parent, "");
    if (status != UCS_OK) {
       return status;
    }

    UCS_STATS_SET_COUNTER(fc->stats, UCT_RC_FC_STAT_FC_WND, fc->fc_wnd);

    return UCS_OK;
}

void uct_rc_fc_cleanup(uct_rc_fc_t *fc)
{
    UCS_STATS_NODE_FREE(fc->stats);
}

void uct_rc_ep_cleanup_qp(uct_rc_ep_t *ep,
                          uct_rc_iface_qp_cleanup_ctx_t *cleanup_ctx,
                          uint32_t qp_num, uint16_t cq_credits)
{
    uct_rc_iface_t *iface = ucs_derived_of(ep->super.super.iface,
                                           uct_rc_iface_t);
    uct_ib_md_t *md       = uct_ib_iface_md(&iface->super);
    ucs_status_t status;

    ucs_assertv(cq_credits < (UINT16_MAX / 2), "cq_credits=%d", cq_credits);

    ucs_list_del(&ep->list);
    uct_rc_iface_remove_qp(iface, qp_num);

    cleanup_ctx->super.cbq  = &iface->super.super.worker->super.progress_q;
    cleanup_ctx->super.cb   = uct_rc_iface_qp_cleanup_progress;
    cleanup_ctx->iface      = iface;
    cleanup_ctx->qp_num     = qp_num;
    cleanup_ctx->cq_credits = cq_credits;
    ucs_list_add_tail(&iface->qp_gc_list, &cleanup_ctx->list);

    status = uct_ib_device_async_event_wait(&md->dev,
                                            IBV_EVENT_QP_LAST_WQE_REACHED,
                                            qp_num, &cleanup_ctx->super);
    ucs_assert_always(status == UCS_OK);
}

UCS_CLASS_INIT_FUNC(uct_rc_ep_t, uct_rc_iface_t *iface, uint32_t qp_num,
                    const uct_ep_params_t *params)
{
    ucs_status_t status;

    UCS_CLASS_CALL_SUPER_INIT(uct_base_ep_t, &iface->super.super);

    status = uct_rc_txqp_init(&self->txqp, iface, qp_num
                              UCS_STATS_ARG(self->super.stats));
    if (status != UCS_OK) {
        return status;
    }

    self->path_index = UCT_EP_PARAMS_GET_PATH_INDEX(params);
    self->flags      = 0;

    status = uct_rc_fc_init(&self->fc, iface UCS_STATS_ARG(self->super.stats));
    if (status != UCS_OK) {
        goto err_txqp_cleanup;
    }

    /* Check that FC protocol fits AM id
     * (just in case AM id space gets extended) */
    UCS_STATIC_ASSERT(UCT_RC_EP_FC_MASK < UINT8_MAX);

    ucs_arbiter_group_init(&self->arb_group);
    ucs_list_add_head(&iface->ep_list, &self->list);

    ucs_debug("created rc ep %p", self);
    return UCS_OK;

err_txqp_cleanup:
    uct_rc_txqp_cleanup(iface, &self->txqp);
    return status;
}

void uct_rc_ep_pending_purge_warn_cb(uct_pending_req_t *self, void *arg)
{
    uct_ep_h ep = arg;
    ucs_warn("ep %p: pending request %p (%s) was not purged", ep, self,
             ucs_debug_get_symbol_name(self->func));
}

static UCS_CLASS_CLEANUP_FUNC(uct_rc_ep_t)
{
    uct_rc_iface_t *iface = ucs_derived_of(self->super.super.iface,
                                           uct_rc_iface_t);

    ucs_debug("destroy rc ep %p", self);

    uct_rc_ep_pending_purge(&self->super.super,
                            uct_rc_ep_pending_purge_warn_cb, self);
    uct_rc_fc_cleanup(&self->fc);
    uct_rc_txqp_cleanup(iface, &self->txqp);
}

UCS_CLASS_DEFINE(uct_rc_ep_t, uct_base_ep_t)

void uct_rc_ep_packet_dump(uct_base_iface_t *iface, uct_am_trace_type_t type,
                           void *data, size_t length, size_t valid_length,
                           char *buffer, size_t max)
{
    uct_rc_hdr_t *rch = data;
    uint8_t fc_hdr    = uct_rc_fc_get_fc_hdr(rch->am_id);
    uint8_t am_wo_fc;

    /* Do not invoke AM tracer for auxiliary pure FC_GRANT message */
    if (fc_hdr != UCT_RC_EP_FC_PURE_GRANT) {
        am_wo_fc = rch->am_id & ~UCT_RC_EP_FC_MASK; /* mask out FC bits*/
        snprintf(buffer, max, " %c%c am %d ",
                 fc_hdr & UCT_RC_EP_FLAG_FC_SOFT_REQ ? 's' :
                 fc_hdr & UCT_RC_EP_FLAG_FC_HARD_REQ ? 'h' : '-',
                 fc_hdr & UCT_RC_EP_FLAG_FC_GRANT    ? 'g' : '-',
                 am_wo_fc);
        uct_iface_dump_am(iface, type, am_wo_fc, rch + 1, length - sizeof(*rch),
                          buffer + strlen(buffer), max - strlen(buffer));
    } else {
        snprintf(buffer, max, " FC pure grant am ");
    }
}

void uct_rc_ep_send_op_set_iov(uct_rc_iface_send_op_t *op, const uct_iov_t *iov,
                               size_t iovcnt)
{
#ifndef NVALGRIND
    size_t op_iovcnt = iovcnt;
    ucs_iov_iter_t iov_iter;

    if (!RUNNING_ON_VALGRIND) {
        return;
    }

    op->iov = ucs_malloc(sizeof(*op->iov) * iovcnt, "rc_get_zcopy_iov");
    if (op->iov == NULL) {
        return;
    }

    ucs_iov_iter_init(&iov_iter);
    uct_iov_to_iovec(op->iov, &op_iovcnt, iov, iovcnt, SIZE_MAX, &iov_iter);
#endif
}

static UCS_F_NOINLINE void
uct_rc_ep_send_op_completed_iov(uct_rc_iface_send_op_t *op)
{
#ifndef NVALGRIND
    struct iovec *iov_entry = op->iov;
    size_t length           = 0;

    ucs_assert(op->flags & UCT_RC_IFACE_SEND_OP_FLAG_IOV);

    if (iov_entry == NULL) {
        return;
    }

    while (length < op->length) {
        /* The memory might not be HOST */
        VALGRIND_MAKE_MEM_DEFINED_IF_ADDRESSABLE(iov_entry->iov_base,
                                                 iov_entry->iov_len);
        length += iov_entry->iov_len;
        ++iov_entry;
    }

    ucs_free(op->iov);
    op->iov = NULL;
#endif
}

static UCS_F_ALWAYS_INLINE void
uct_rc_op_release_get_bcopy(uct_rc_iface_send_op_t *op)
{
    uct_rc_iface_send_desc_t *desc = ucs_derived_of(op, uct_rc_iface_send_desc_t);
    uct_rc_iface_t          *iface = ucs_container_of(ucs_mpool_obj_owner(desc),
                                                      uct_rc_iface_t, tx.mp);

    iface->tx.reads_completed += op->length;
}

static UCS_F_ALWAYS_INLINE void
uct_rc_op_release_get_zcopy(uct_rc_iface_send_op_t *op)
{
    op->iface->tx.reads_completed += op->length;

    if (RUNNING_ON_VALGRIND) {
        uct_rc_ep_send_op_completed_iov(op);
    }

    op->flags &= ~UCT_RC_IFACE_SEND_OP_FLAG_IOV;
}

void uct_rc_ep_get_bcopy_handler(uct_rc_iface_send_op_t *op, const void *resp)
{
    uct_rc_iface_send_desc_t *desc = ucs_derived_of(op, uct_rc_iface_send_desc_t);

    VALGRIND_MAKE_MEM_DEFINED(resp, desc->super.length);

    desc->unpack_cb(desc->super.unpack_arg, resp, desc->super.length);

    uct_rc_op_release_get_bcopy(op);
    uct_invoke_completion(desc->super.user_comp, UCS_OK);
    ucs_mpool_put(desc);
}

void uct_rc_ep_get_bcopy_handler_no_completion(uct_rc_iface_send_op_t *op,
                                               const void *resp)
{
    uct_rc_iface_send_desc_t *desc = ucs_derived_of(op, uct_rc_iface_send_desc_t);

    VALGRIND_MAKE_MEM_DEFINED(resp, desc->super.length);

    desc->unpack_cb(desc->super.unpack_arg, resp, desc->super.length);
    uct_rc_op_release_get_bcopy(op);
    ucs_mpool_put(desc);
}

void uct_rc_ep_flush_remote_handler(uct_rc_iface_send_op_t *op,
                                    const void *resp)
{
    uct_rc_iface_send_desc_t *desc = ucs_derived_of(op, uct_rc_iface_send_desc_t);

    uct_invoke_completion(desc->super.user_comp, UCS_OK);
    ucs_mpool_put(desc);
}

void uct_rc_ep_get_zcopy_completion_handler(uct_rc_iface_send_op_t *op,
                                            const void *resp)
{
    uct_rc_op_release_get_zcopy(op);
    uct_rc_ep_send_op_completion_handler(op, resp);
}

void uct_rc_ep_send_op_completion_handler(uct_rc_iface_send_op_t *op,
                                          const void *resp)
{
    uct_invoke_completion(op->user_comp, UCS_OK);
    uct_rc_iface_put_send_op(op);
}

void uct_rc_ep_flush_op_completion_handler(uct_rc_iface_send_op_t *op,
                                           const void *resp)
{
    uct_invoke_completion(op->user_comp, UCS_OK);
    ucs_mpool_put(op);
}

ucs_status_t uct_rc_ep_pending_add(uct_ep_h tl_ep, uct_pending_req_t *n,
                                   unsigned flags)
{
    uct_rc_iface_t *iface = ucs_derived_of(tl_ep->iface, uct_rc_iface_t);
    uct_rc_ep_t *ep = ucs_derived_of(tl_ep, uct_rc_ep_t);

    if (uct_rc_ep_has_tx_resources(ep) &&
        uct_rc_iface_has_tx_resources(iface)) {
        return UCS_ERR_BUSY;
    }

    UCS_STATIC_ASSERT(sizeof(uct_pending_req_priv_arb_t) <=
                      UCT_PENDING_REQ_PRIV_LEN);
    uct_pending_req_arb_group_push(&ep->arb_group, n);
    UCT_TL_EP_STAT_PEND(&ep->super);

    if (uct_rc_ep_has_tx_resources(ep)) {
        /* If we have ep (but not iface) resources, we need to schedule the ep */
        ucs_arbiter_group_schedule(&iface->tx.arbiter, &ep->arb_group);
    }

    return UCS_OK;
}

ucs_arbiter_cb_result_t uct_rc_ep_process_pending(ucs_arbiter_t *arbiter,
                                                  ucs_arbiter_group_t *group,
                                                  ucs_arbiter_elem_t *elem,
                                                  void *arg)
{
    uct_pending_req_t *req = ucs_container_of(elem, uct_pending_req_t, priv);
    uct_rc_ep_t *ep        = ucs_container_of(group, uct_rc_ep_t, arb_group);
    uct_rc_iface_t *iface  = ucs_derived_of(ep->super.super.iface, uct_rc_iface_t);
    ucs_status_t status;

    status = uct_rc_iface_invoke_pending_cb(iface, req);
    if (status == UCS_OK) {
        return UCS_ARBITER_CB_RESULT_REMOVE_ELEM;
    } else if (status == UCS_INPROGRESS) {
        return UCS_ARBITER_CB_RESULT_NEXT_GROUP;
    } else if (!uct_rc_iface_has_tx_resources(iface)) {
        /* No iface resources */
        return UCS_ARBITER_CB_RESULT_STOP;
    }

    /* No any other pending operations (except no-op, flush(CANCEL), and others
     * which don't consume TX resources) allowed to be still scheduled on an
     * arbiter group for which flush(CANCEL) was done */
    ucs_assert(!(ep->flags & UCT_RC_EP_FLAG_FLUSH_CANCEL));

    /* No ep resources */
    ucs_assertv(!uct_rc_ep_has_tx_resources(ep),
                "pending callback returned error, but send resources are"
                " available");
    return UCS_ARBITER_CB_RESULT_DESCHED_GROUP;
}

ucs_arbiter_cb_result_t
uct_rc_ep_arbiter_purge_internal_cb(ucs_arbiter_t *arbiter,
                                    ucs_arbiter_group_t *group,
                                    ucs_arbiter_elem_t *elem, void *arg)
{
    uct_pending_req_t *req = ucs_container_of(elem, uct_pending_req_t, priv);
    uct_rc_ep_t *ep        = ucs_container_of(group, uct_rc_ep_t, arb_group);
    uct_rc_pending_req_t *freq;

    if (req->func == uct_rc_ep_check_progress) {
        ep->flags &= ~UCT_RC_EP_FLAG_KEEPALIVE_PENDING;
        ucs_mpool_put(req);
    } else if (req->func == uct_rc_ep_fc_grant) {
        freq = ucs_derived_of(req, uct_rc_pending_req_t);
        ucs_mpool_put(freq);
    } else {
        /* Non-internal request was found */
        return UCS_ARBITER_CB_RESULT_RESCHED_GROUP;
    }

    /* Internal request was found */
    return UCS_ARBITER_CB_RESULT_REMOVE_ELEM;
}

ucs_arbiter_cb_result_t uct_rc_ep_arbiter_purge_cb(ucs_arbiter_t *arbiter,
                                                   ucs_arbiter_group_t *group,
                                                   ucs_arbiter_elem_t *elem,
                                                   void *arg)
{
    uct_pending_req_t *req          = ucs_container_of(elem, uct_pending_req_t,
                                                       priv);
    uct_purge_cb_args_t *cb_args    = arg;
    uct_pending_purge_callback_t cb = cb_args->cb;
    uct_rc_ep_t *ep                 = ucs_container_of(group, uct_rc_ep_t,
                                                       arb_group);
    ucs_arbiter_cb_result_t result;

    result = uct_rc_ep_arbiter_purge_internal_cb(arbiter, group, elem, arg);
    if (result != UCS_ARBITER_CB_RESULT_REMOVE_ELEM) {
        if (cb != NULL) {
            cb(req, cb_args->arg);
        } else {
            ucs_debug("ep=%p cancelling user pending request %p", ep, req);
        }
    }
    return UCS_ARBITER_CB_RESULT_REMOVE_ELEM;
}

void uct_rc_ep_pending_purge(uct_ep_h tl_ep, uct_pending_purge_callback_t cb,
                             void *arg)
{
    uct_rc_iface_t *iface    = ucs_derived_of(tl_ep->iface, uct_rc_iface_t);
    uct_rc_ep_t *ep          = ucs_derived_of(tl_ep, uct_rc_ep_t);
    uct_purge_cb_args_t args = {cb, arg};

    ucs_arbiter_group_purge(&iface->tx.arbiter, &ep->arb_group,
                            uct_rc_ep_arbiter_purge_cb, &args);
}

ucs_status_t uct_rc_ep_fc_grant(uct_pending_req_t *self)
{
    ucs_status_t status;
    uct_rc_pending_req_t *freq = ucs_derived_of(self, uct_rc_pending_req_t);
    uct_rc_ep_t *ep            = ucs_derived_of(freq->ep, uct_rc_ep_t);
    uct_rc_iface_t *iface      = ucs_derived_of(ep->super.super.iface,
                                                uct_rc_iface_t);

    ucs_assert_always(iface->config.fc_enabled);
    status = uct_rc_fc_ctrl(&ep->super.super, UCT_RC_EP_FC_PURE_GRANT, NULL);
    if (status == UCS_OK) {
        UCS_STATS_UPDATE_COUNTER(ep->fc.stats, UCT_RC_FC_STAT_TX_PURE_GRANT, 1);
        ucs_mpool_put(freq);
    }
    return status;
}

void uct_rc_txqp_purge_outstanding(uct_rc_iface_t *iface, uct_rc_txqp_t *txqp,
                                   ucs_status_t status, uint16_t sn, int warn)
{
    uct_rc_iface_send_op_t *op;
    uct_rc_iface_send_desc_t *desc;

    ucs_queue_for_each_extract(op, &txqp->outstanding, queue,
                               UCS_CIRCULAR_COMPARE16(op->sn, <=, sn)) {
        if (op->handler != (uct_rc_send_handler_t)ucs_mpool_put) {
            /* Allow clean flush cancel op from destroy flow */
            if (warn &&
                (op->handler != uct_rc_ep_flush_op_completion_handler)) {
                ucs_warn("destroying txqp %p with uncompleted operation %p"
                         " handler %s",
                         txqp, op, ucs_debug_get_symbol_name(op->handler));
            }

            if (op->user_comp != NULL) {
                /* This must be uct_rc_ep_get_bcopy_handler,
                 * uct_rc_ep_get_bcopy_handler_no_completion,
                 * uct_rc_ep_get_zcopy_completion_handler,
                 * uct_rc_ep_flush_op_completion_handler or
                 * one of the atomic handlers,
                 * so invoke user completion */
                uct_invoke_completion(op->user_comp, status);
            }

            /* Need to release rdma_read resources taken by get operations  */
            if ((op->handler == uct_rc_ep_get_bcopy_handler) ||
                (op->handler == uct_rc_ep_get_bcopy_handler_no_completion)) {
                uct_rc_op_release_get_bcopy(op);
                uct_rc_iface_update_reads(iface);
            } else if (op->handler == uct_rc_ep_get_zcopy_completion_handler) {
                uct_rc_op_release_get_zcopy(op);
                uct_rc_iface_update_reads(iface);
            }
        }

        op->flags &= ~(UCT_RC_IFACE_SEND_OP_FLAG_INUSE |
                       UCT_RC_IFACE_SEND_OP_FLAG_ZCOPY);

        if ((op->handler == uct_rc_ep_send_op_completion_handler) ||
            (op->handler == uct_rc_ep_get_zcopy_completion_handler)) {
            uct_rc_iface_put_send_op(op);
        } else if (op->handler == uct_rc_ep_flush_op_completion_handler) {
            ucs_mpool_put(op);
        } else if ((op->handler == iface->config.atomic32_ext_handler) ||
                   (op->handler == iface->config.atomic64_ext_handler) ||
                   (op->handler == iface->config.atomic64_handler) ||
                   (op->handler == uct_rc_ep_get_bcopy_handler) ||
                   (op->handler == uct_rc_ep_get_bcopy_handler_no_completion) ||
                   (op->handler == uct_rc_ep_am_zcopy_handler)) {
            desc = ucs_derived_of(op, uct_rc_iface_send_desc_t);
            ucs_mpool_put(desc);
        } else {
            op->status = status;
            op->flags |= UCT_RC_IFACE_SEND_OP_STATUS;
            op->handler(op, NULL);
        }
    }
}

ucs_status_t uct_rc_ep_flush(uct_rc_ep_t *ep, int16_t max_available,
                             unsigned flags)
{
    uct_rc_iface_t *iface = ucs_derived_of(ep->super.super.iface,
                                           uct_rc_iface_t);

    if (!uct_rc_iface_has_tx_resources(iface) ||
        (uct_rc_txqp_available(&ep->txqp) <= 0)) {
        return UCS_ERR_NO_RESOURCE;
    }

    /* Ignore FC limitations when performing flush(CANCEL) */
    if (!uct_rc_fc_has_resources(iface, &ep->fc) &&
        !(flags & UCT_FLUSH_FLAG_CANCEL)) {
        return UCS_ERR_NO_RESOURCE;
    }

    if (uct_rc_txqp_available(&ep->txqp) == max_available) {
        UCT_TL_EP_STAT_FLUSH(&ep->super);
        return UCS_OK;
    }

    if (ucs_unlikely(flags & UCT_FLUSH_FLAG_CANCEL)) {
        ep->flags |= UCT_RC_EP_FLAG_FLUSH_CANCEL;
    }

    return UCS_INPROGRESS;
}

static ucs_status_t uct_rc_ep_check_internal(uct_ep_h tl_ep)
{
    uct_rc_ep_t *ep         = ucs_derived_of(tl_ep, uct_rc_ep_t);
    uct_rc_iface_t *iface   = ucs_derived_of(tl_ep->iface,
                                            uct_rc_iface_t);
    uct_rc_iface_ops_t *ops = ucs_derived_of(iface->super.ops, uct_rc_iface_ops_t);

    /* in case if no TX resources are available then there is at least
     * one signaled operation which provides actual peer status, in this case
     * just return without any actions */
    UCT_RC_CHECK_TXQP_RET(iface, ep, UCS_OK);

    /* in case of not iface resources available then return NO_RESOURCE
     * to add request to pending queue */
    UCT_RC_CHECK_CQE_RET(iface, ep, UCS_ERR_NO_RESOURCE);

    ops->ep_post_check(tl_ep);

    return UCS_OK;
}

static ucs_status_t uct_rc_ep_check_progress(uct_pending_req_t *self)
{
    uct_rc_pending_req_t *req = ucs_derived_of(self, uct_rc_pending_req_t);
    uct_rc_ep_t *ep           = ucs_derived_of(req->ep, uct_rc_ep_t);
    ucs_status_t status;

    ucs_assert(ep->flags & UCT_RC_EP_FLAG_KEEPALIVE_PENDING);

    status = uct_rc_ep_check_internal(req->ep);
    if (status == UCS_OK) {
        ep->flags &= ~UCT_RC_EP_FLAG_KEEPALIVE_PENDING;
        ucs_mpool_put(req);
    } else {
        ucs_assert(status == UCS_ERR_NO_RESOURCE);
    }

    return status;
}

ucs_status_t
uct_rc_ep_check(uct_ep_h tl_ep, unsigned flags, uct_completion_t *comp)
{
    uct_rc_ep_t *ep       = ucs_derived_of(tl_ep, uct_rc_ep_t);
    uct_rc_iface_t *iface = ucs_derived_of(tl_ep->iface,
                                           uct_rc_iface_t);
    uct_rc_pending_req_t *req;
    ucs_status_t status;

    UCT_EP_KEEPALIVE_CHECK_PARAM(flags, comp);

    ucs_assert(ep->flags & UCT_RC_EP_FLAG_CONNECTED);

    if (ep->flags & UCT_RC_EP_FLAG_KEEPALIVE_PENDING) {
        /* keepalive request is in pending queue and will be
         * processed when resources are available */
        return UCS_OK;
    }

    status = uct_rc_ep_check_internal(tl_ep);
    if (status != UCS_ERR_NO_RESOURCE) {
        ucs_assert(status == UCS_OK);
        return status;
    }

    /* there are no iface resources, add pending request */
    req = ucs_mpool_get(&iface->tx.pending_mp);
    if (req == NULL) {
        return UCS_ERR_NO_MEMORY;
    }

    req->ep          = &ep->super.super;
    req->super.func  = uct_rc_ep_check_progress;
    status           = uct_rc_ep_pending_add(tl_ep, &req->super, 0);
    ep->flags       |= UCT_RC_EP_FLAG_KEEPALIVE_PENDING;
    ucs_assert_always(status == UCS_OK);

    return UCS_OK;
}

#define UCT_RC_DEFINE_ATOMIC_HANDLER_FUNC(_num_bits, _is_be) \
    void UCT_RC_DEFINE_ATOMIC_HANDLER_FUNC_NAME(_num_bits, _is_be) \
            (uct_rc_iface_send_op_t *op, const void *resp) \
    { \
        uct_rc_iface_send_desc_t *desc = \
            ucs_derived_of(op, uct_rc_iface_send_desc_t); \
        const uint##_num_bits##_t *value = resp; \
        uint##_num_bits##_t *dest = desc->super.buffer; \
        \
        VALGRIND_MAKE_MEM_DEFINED(value, sizeof(*value)); \
        if (_is_be && (_num_bits == 32)) { \
            *dest = ntohl(*value); /* TODO swap in-place */ \
        } else if (_is_be && (_num_bits == 64)) { \
            *dest = be64toh(*value); \
        } else { \
            *dest = *value; \
        } \
        \
        uct_invoke_completion(desc->super.user_comp, UCS_OK); \
        ucs_mpool_put(desc); \
  }

UCT_RC_DEFINE_ATOMIC_HANDLER_FUNC(32, 0);
UCT_RC_DEFINE_ATOMIC_HANDLER_FUNC(32, 1);
UCT_RC_DEFINE_ATOMIC_HANDLER_FUNC(64, 0);
UCT_RC_DEFINE_ATOMIC_HANDLER_FUNC(64, 1);

void uct_rc_ep_am_zcopy_handler(uct_rc_iface_send_op_t *op, const void *resp)
{
    uct_rc_iface_send_desc_t *desc = ucs_derived_of(op, uct_rc_iface_send_desc_t);
    uct_invoke_completion(desc->super.user_comp, UCS_OK);
    ucs_mpool_put(desc);
}
