/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
/*
 * Copyright (c) 2004-2008 The Trustees of Indiana University and Indiana
 *                         University Research and Technology
 *                         Corporation.  All rights reserved.
 * Copyright (c) 2004-2011 The University of Tennessee and The University
 *                         of Tennessee Research Foundation.  All rights
 *                         reserved.
 * Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
 *                         University of Stuttgart.  All rights reserved.
 * Copyright (c) 2004-2005 The Regents of the University of California.
 *                         All rights reserved.
 * Copyright (c) 2006      Sandia National Laboratories. All rights
 *                         reserved.
 * Copyright (c) 2008-2017 Cisco Systems, Inc.  All rights reserved.
 * Copyright (c) 2012-2014 Los Alamos National Security, LLC.  All rights
 *                         reserved.
 * Copyright (c) 2014      Intel, Inc. All rights reserved.
 * Copyright (c) 2015      Research Organization for Information Science
 *                         and Technology (RIST). All rights reserved.
 * $COPYRIGHT$
 *
 * Additional copyrights may follow
 *
 * $HEADER$
 */

/*
 * General notes:
 *
 * - OB1 handles out of order receives
 * - OB1 does NOT handle duplicate receives well (it probably does for
 *   MATCH tags, but for non-MATCH tags, it doesn't have enough info
 *   to know when duplicates are received), so we have to ensure not
 *   to pass duplicates up to the PML.
 */

#include "opal_config.h"

#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include <rdma/fabric.h>

#include "opal_stdint.h"
#include "opal/prefetch.h"
#include "opal/mca/timer/base/base.h"
#include "opal/util/argv.h"
#include "opal/util/net.h"
#include "opal/util/if.h"
#include "opal/mca/base/mca_base_var.h"
#include "opal/mca/memchecker/base/base.h"
#include "opal/util/show_help.h"
#include "opal/constants.h"

#if BTL_IN_OPAL
#include "opal/mca/btl/btl.h"
#include "opal/mca/btl/base/base.h"
#include "opal/util/proc.h"
#else
#include "ompi/mca/btl/btl.h"
#include "ompi/mca/btl/base/base.h"
#include "ompi/proc/proc.h"
#endif

#include "btl_usnic.h"
#include "btl_usnic_connectivity.h"
#include "btl_usnic_frag.h"
#include "btl_usnic_endpoint.h"
#include "btl_usnic_module.h"
#include "btl_usnic_stats.h"
#include "btl_usnic_util.h"
#include "btl_usnic_ack.h"
#include "btl_usnic_send.h"
#include "btl_usnic_recv.h"
#include "btl_usnic_proc.h"
#include "btl_usnic_test.h"

#define OPAL_BTL_USNIC_NUM_COMPLETIONS 500

/* MPI_THREAD_MULTIPLE_SUPPORT */
opal_recursive_mutex_t btl_usnic_lock =  OPAL_RECURSIVE_MUTEX_STATIC_INIT;

/* RNG buffer definition */
opal_rng_buff_t opal_btl_usnic_rand_buff = {{0}};

/* simulated clock */
uint64_t opal_btl_usnic_ticks = 0;

static opal_event_t usnic_clock_timer_event;
static bool usnic_clock_timer_event_set = false;
static struct timeval usnic_clock_timeout;

/* set to true in a debugger to enable even more verbose output when calling
 * opal_btl_usnic_component_debug */
static volatile bool dump_bitvectors = false;

static int usnic_component_open(void);
static int usnic_component_close(void);
static mca_btl_base_module_t **
usnic_component_init(int* num_btl_modules, bool want_progress_threads,
                       bool want_mpi_threads);
static int usnic_component_progress(void);

/* Types for filtering interfaces */
typedef struct filter_elt_t {
    bool is_netmask;

    /* valid iff is_netmask==false */
    char *if_name;

    /* valid iff is_netmask==true */
    uint32_t addr_be; /* in network byte order */
    uint32_t netmask_be;
} filter_elt_t;

typedef struct usnic_if_filter_t {
    int n_elt;
    filter_elt_t *elts;
} usnic_if_filter_t;

static bool filter_module(opal_btl_usnic_module_t *module,
                          usnic_if_filter_t *filter,
                          bool filter_incl);
static usnic_if_filter_t *parse_ifex_str(const char *orig_str,
                                         const char *name);
static void free_filter(usnic_if_filter_t *filter);


opal_btl_usnic_component_t mca_btl_usnic_component = {
    .super = {
        /* First, the mca_base_component_t struct containing meta information
           about the component itself */
        .btl_version = {
            USNIC_BTL_DEFAULT_VERSION("usnic"),
            .mca_open_component = usnic_component_open,
            .mca_close_component = usnic_component_close,
            .mca_register_component_params = opal_btl_usnic_component_register,
        },
        .btl_data = {
            /* The component is not checkpoint ready */
            .param_field = MCA_BASE_METADATA_PARAM_NONE
        },

        .btl_init = usnic_component_init,
        .btl_progress = usnic_component_progress,
    }
};


/*
 *  Called by MCA framework to open the component
 */
static int usnic_component_open(void)
{
    /* initialize state */
    mca_btl_usnic_component.num_modules = 0;
    mca_btl_usnic_component.usnic_all_modules = NULL;
    mca_btl_usnic_component.usnic_active_modules = NULL;
    mca_btl_usnic_component.transport_header_len = -1;
    mca_btl_usnic_component.prefix_send_offset = 0;

    /* initialize objects */
    OBJ_CONSTRUCT(&mca_btl_usnic_component.usnic_procs, opal_list_t);

    /* Sanity check: if_include and if_exclude need to be mutually
       exclusive */
    if (OPAL_SUCCESS !=
        mca_base_var_check_exclusive("opal",
            mca_btl_usnic_component.super.btl_version.mca_type_name,
            mca_btl_usnic_component.super.btl_version.mca_component_name,
            "if_include",
            mca_btl_usnic_component.super.btl_version.mca_type_name,
            mca_btl_usnic_component.super.btl_version.mca_component_name,
            "if_exclude")) {
        /* Return ERR_NOT_AVAILABLE so that a warning message about
           "open" failing is not printed */
        return OPAL_ERR_NOT_AVAILABLE;
    }

    return OPAL_SUCCESS;
}


/*
 * Component cleanup
 */
static int usnic_component_close(void)
{
    /* Note that this list should already be empty, because:
       - module.finalize() is invoked before component.close()
       - module.finalize() RELEASEs each proc that it was using
       - this should drive down the ref count on procs to 0
       - procs remove themselves from the component.usnic_procs list
         in their destructor */
    OBJ_DESTRUCT(&mca_btl_usnic_component.usnic_procs);

    if (usnic_clock_timer_event_set) {
        opal_event_del(&usnic_clock_timer_event);
        usnic_clock_timer_event_set = false;
    }

    /* Finalize the connectivity client and agent */
    if (mca_btl_usnic_component.connectivity_enabled) {
        opal_btl_usnic_connectivity_client_finalize();
        opal_btl_usnic_connectivity_agent_finalize();
    }
    if (mca_btl_usnic_component.opal_evbase) {
        opal_progress_thread_finalize(NULL);
    }

    free(mca_btl_usnic_component.usnic_all_modules);
    free(mca_btl_usnic_component.usnic_active_modules);

#if OPAL_BTL_USNIC_UNIT_TESTS
    /* clean up the unit test infrastructure */
    opal_btl_usnic_cleanup_tests();
#endif

    OBJ_DESTRUCT(&btl_usnic_lock);

    return OPAL_SUCCESS;
}


/*
 * Register address information.  The modex will make this available
 * to all peers.
 */
static int usnic_modex_send(void)
{
    int rc;
    int i;
    size_t size;
    opal_btl_usnic_modex_t* modexes = NULL;

    if (0 == mca_btl_usnic_component.num_modules) {
        return OPAL_SUCCESS;
    }

    size = mca_btl_usnic_component.num_modules *
        sizeof(opal_btl_usnic_modex_t);
    modexes = (opal_btl_usnic_modex_t*) malloc(size);
    if (NULL == modexes) {
        return OPAL_ERR_OUT_OF_RESOURCE;
    }

    for (i = 0; i < mca_btl_usnic_component.num_modules; i++) {
        opal_btl_usnic_module_t* module =
            mca_btl_usnic_component.usnic_active_modules[i];
        modexes[i] = module->local_modex;
        opal_output_verbose(5, USNIC_OUT,
                            "btl:usnic: "
                            "control port:%d, "
                            "modex_send data port:%d, "
                            "%s",
                            modexes[i].ports[USNIC_PRIORITY_CHANNEL],
                            modexes[i].ports[USNIC_DATA_CHANNEL],
                            module->if_ipv4_addr_str);
    }

    usnic_compat_modex_send(&rc, &mca_btl_usnic_component.super.btl_version,
                            modexes, size);
    free(modexes);

    return rc;
}


/*
 * See if our memlock limit is >64K.  64K is the RHEL default memlock
 * limit; this check is a first-line-of-defense hueristic to see if
 * the user has set the memlock limit to *something*.
 *
 * We have other checks elsewhere (e.g., to ensure that QPs are able
 * to be allocated -- which also require registered memory -- and to
 * ensure that receive buffers can be registered, etc.), but this is a
 * good first check to ensure that a default OS case is satisfied.
 */
static int check_reg_mem_basics(void)
{
#if HAVE_DECL_RLIMIT_MEMLOCK
    int ret = OPAL_SUCCESS;
    struct rlimit limit;
    char *str_limit = NULL;

    ret = getrlimit(RLIMIT_MEMLOCK, &limit);
    if (0 == ret) {
        if ((long) limit.rlim_cur > (64 * 1024) ||
            limit.rlim_cur == RLIM_INFINITY) {
            return OPAL_SUCCESS;
        } else {
            asprintf(&str_limit, "%ld", (long)limit.rlim_cur);
        }
    } else {
        asprintf(&str_limit, "Unknown");
    }

    opal_show_help("help-mpi-btl-usnic.txt", "check_reg_mem_basics fail",
                   true,
                   opal_process_info.nodename,
                   str_limit);

    return OPAL_ERR_OUT_OF_RESOURCE;
#else
    /* If we don't have RLIMIT_MEMLOCK, then just bypass this
       safety/hueristic check. */
    return OPAL_SUCCESS;
#endif
}


/*
 * Basic sanity checking for usNIC VFs / resources.
 */
static int check_usnic_config(opal_btl_usnic_module_t *module,
        int num_local_procs)
{
    char str[128];
    unsigned unlp;
    struct fi_usnic_info *uip;

    uip = &module->usnic_info;

    /* Note: we add one to num_local_procs to account for *this*
       process */
    unlp = (unsigned) num_local_procs + 1;

    /* usNIC allocates QPs as a combination of PCI virtual functions
       (VFs) and resources inside those VFs.  Ensure that:

       1. num_vfs (i.e., "usNICs") >= num_local_procs (to ensure that
          each MPI process will be able to have its own protection
          domain), and
       2. num_qps_per_vf >= NUM_CHANNELS
          (to ensure that each MPI process will be able to get the
          number of QPs it needs -- we know that every VF will have
          the same number of QPs), and
       3. num_cqs_per_vf >= NUM_CHANNELS
          (to ensure that each MPI process will be able to get the
          number of CQs that it needs) */
    if (uip->ui.v1.ui_num_vf < unlp) {
        snprintf(str, sizeof(str), "Not enough usNICs (found %d, need %d)",
                 uip->ui.v1.ui_num_vf, unlp);
        goto error;
    }

    if (uip->ui.v1.ui_qp_per_vf < USNIC_NUM_CHANNELS) {
        snprintf(str, sizeof(str), "Not enough transmit/receive queues per usNIC (found %d, need %d)",
                 uip->ui.v1.ui_qp_per_vf,
                 USNIC_NUM_CHANNELS);
        goto error;
    }
    if (uip->ui.v1.ui_cq_per_vf < USNIC_NUM_CHANNELS) {
        snprintf(str, sizeof(str),
                 "Not enough completion queues per usNIC (found %d, need %d)",
                 uip->ui.v1.ui_cq_per_vf,
                 USNIC_NUM_CHANNELS);
        goto error;
    }

    /* All is good! */
    return OPAL_SUCCESS;

 error:
    /* Sad panda */
    opal_show_help("help-mpi-btl-usnic.txt",
                   "not enough usnic resources",
                   true,
                   opal_process_info.nodename,
                   module->linux_device_name,
                   str);
    return OPAL_ERROR;
}


static void usnic_clock_callback(int fd, short flags, void *timeout)
{
    /* 1ms == 1,000,000 ns */
    opal_btl_usnic_ticks += 1000000;

    /* run progress to make sure time change gets noticed */
    usnic_component_progress();

    opal_event_add(&usnic_clock_timer_event, timeout);
}


/* Parse a string which is a comma-separated list containing a mix of
 * interface names and IPv4 CIDR-format netmasks.
 *
 * Gracefully tolerates NULL pointer arguments by returning NULL.
 *
 * Returns a usnic_if_filter_t, which contains n_elt and a
 * corresponding array of found filter elements.  Caller is
 * responsible for freeing the returned usnic_if_filter_t, the array
 * of filter elements, and any strings in it (can do this via
 * free_filter()).
 */
static usnic_if_filter_t *parse_ifex_str(const char *orig_str,
                                         const char *name)
{
    int i, ret;
    char **argv, *str, *tmp;
    struct sockaddr_storage argv_inaddr;
    uint32_t argv_prefix, addr;
    usnic_if_filter_t *filter;
    int n_argv;

    if (NULL == orig_str) {
        return NULL;
    }

    /* Get a wrapper for the filter */
    filter = calloc(sizeof(*filter), 1);
    if (NULL == filter) {
        OPAL_ERROR_LOG(OPAL_ERR_OUT_OF_RESOURCE);
        return NULL;
    }

    argv = opal_argv_split(orig_str, ',');
    if (NULL == argv || 0 == (n_argv = opal_argv_count(argv))) {
        free(filter);
        opal_argv_free(argv);
        return NULL;
    }

    /* upper bound: each entry could be a mask */
    filter->elts = malloc(sizeof(*filter->elts) * n_argv);
    if (NULL == filter->elts) {
        OPAL_ERROR_LOG(OPAL_ERR_OUT_OF_RESOURCE);
        free(filter);
        opal_argv_free(argv);
        return NULL;
    }

    /* Shuffle iface names to the beginning of the argv array.  Process each
     * netmask as we encounter it and append the resulting value to netmask_t
     * array which we will return. */
    filter->n_elt = 0;
    for (i = 0; NULL != argv[i]; ++i) {
        /* assume that all interface names begin with an alphanumeric
         * character, not a number */
        if (isalpha(argv[i][0])) {
            filter->elts[filter->n_elt].is_netmask = false;
            filter->elts[filter->n_elt].if_name = strdup(argv[i]);
            opal_output_verbose(20, USNIC_OUT,
                                "btl:usnic:parse_ifex_str: parsed %s device name: %s",
                                name, filter->elts[filter->n_elt].if_name);

            ++filter->n_elt;
            continue;
        }

        /* Found a subnet notation.  Convert it to an IP
           address/netmask.  Get the prefix first. */
        argv_prefix = 0;
        tmp = strdup(argv[i]);
        str = strchr(argv[i], '/');
        if (NULL == str) {
            opal_show_help("help-mpi-btl-usnic.txt", "invalid if_inexclude",
                           true, name, opal_process_info.nodename,
                           tmp, "Invalid specification (missing \"/\")");
            free(tmp);
            continue;
        }
        *str = '\0';
        argv_prefix = atoi(str + 1);
        if (argv_prefix < 1 || argv_prefix > 32) {
            opal_show_help("help-mpi-btl-usnic.txt", "invalid if_inexclude",
                           true, name, opal_process_info.nodename,
                           tmp, "Invalid specification (prefix < 1 or prefix >32)");
            free(tmp);
            continue;
        }

        /* Now convert the IPv4 address */
        ((struct sockaddr*) &argv_inaddr)->sa_family = AF_INET;
        ret = inet_pton(AF_INET, argv[i],
                        &((struct sockaddr_in*) &argv_inaddr)->sin_addr);
        if (1 != ret) {
            opal_show_help("help-mpi-btl-usnic.txt", "invalid if_inexclude",
                           true, name, opal_process_info.nodename, tmp,
                           "Invalid specification (inet_pton() failed)");
            free(tmp);
            continue;
        }
        opal_output_verbose(20, USNIC_OUT,
                            "btl:usnic:parse_ifex_str: parsed %s address+prefix: %s / %u",
                            name,
                            opal_net_get_hostname((struct sockaddr*) &argv_inaddr),
                            argv_prefix);

        memcpy(&addr,
               &((struct sockaddr_in*) &argv_inaddr)->sin_addr,
               sizeof(addr));

        /* be helpful: if the user passed A.B.C.D/24 instead of A.B.C.0/24,
         * also normalize the netmask */
        filter->elts[filter->n_elt].is_netmask = true;
        filter->elts[filter->n_elt].if_name = NULL;
        filter->elts[filter->n_elt].netmask_be =
            usnic_cidrlen_to_netmask(argv_prefix);
        filter->elts[filter->n_elt].addr_be = addr &
            filter->elts[filter->n_elt].netmask_be;
        ++filter->n_elt;

        free(tmp);
    }
    assert(i == n_argv); /* sanity */

    opal_argv_free(argv);

    /* don't return an empty filter */
    if (filter->n_elt == 0) {
        free_filter(filter);
        return NULL;
    }

    return filter;
}

/*
 * Check this module to see if should be kept or not.
 */
static bool filter_module(opal_btl_usnic_module_t *module,
                          usnic_if_filter_t *filter,
                          bool filter_incl)
{
    int i;
    uint32_t module_mask;
    struct sockaddr_in *src;
    struct fi_usnic_info *uip;
    struct fi_info *info;
    bool match;
    const char *linux_device_name;

    info = module->fabric_info;
    uip = &module->usnic_info;
    src = info->src_addr;
    linux_device_name = module->linux_device_name;
    module_mask = src->sin_addr.s_addr & uip->ui.v1.ui_netmask_be;
    match = false;
    for (i = 0; i < filter->n_elt; ++i) {
        if (filter->elts[i].is_netmask) {
            /* conservative: we also require the netmask to match */
            if (filter->elts[i].netmask_be == uip->ui.v1.ui_netmask_be &&
                filter->elts[i].addr_be == module_mask) {
                match = true;
                break;
            }
        }
        else {
            if (strcmp(filter->elts[i].if_name, linux_device_name) == 0) {
                match = true;
                break;
            }
        }
    }

    /* Turn the match result into whether we should keep it or not */
    return match ^ !filter_incl;
}

/* utility routine to safely free a filter element array */
static void free_filter(usnic_if_filter_t *filter)
{
    int i;

    if (filter == NULL) {
        return;
    }

    if (NULL != filter->elts) {
        for (i = 0; i < filter->n_elt; ++i) {
            if (!filter->elts[i].is_netmask) {
                free(filter->elts[i].if_name);
            }
        }
        free(filter->elts);
    }
    free(filter);
}

/*
 *  UD component initialization:
 *  (1) read interface list from kernel and compare against component
 *      parameters then create a BTL instance for selected interfaces
 *  (2) post OOB receive for incoming connection attempts
 *  (3) register BTL parameters with the MCA
 */
static mca_btl_base_module_t** usnic_component_init(int* num_btl_modules,
                                                    bool want_progress_threads,
                                                    bool want_mpi_threads)
{
    mca_btl_base_module_t **btls = NULL;
    int i, j, num_final_modules;
    int num_devs;
    opal_btl_usnic_module_t *module;
    usnic_if_filter_t *filter = NULL;
    bool keep_module;
    bool filter_incl = false;
    int min_distance, num_local_procs;
    struct fi_info *info_list;
    struct fi_info *info;
    struct fid_fabric *fabric;
    struct fid_domain *domain;
    int ret;

    *num_btl_modules = 0;

    /* MPI_THREAD_MULTIPLE is only supported in 2.0+ */
    if (want_mpi_threads && !mca_btl_base_thread_multiple_override) {
	if (OPAL_MAJOR_VERSION >= 2) {
            opal_output_verbose(5, USNIC_OUT,
                                "btl:usnic: MPI_THREAD_MULTIPLE support is in testing phase.");
	}
	else {
            opal_output_verbose(5, USNIC_OUT,
                                "btl:usnic: MPI_THREAD_MULTIPLE is not supported in version < 2.");
	    return NULL;
	}
    }

    OBJ_CONSTRUCT(&btl_usnic_lock, opal_recursive_mutex_t);

    /* There are multiple dimensions to consider when requesting an
       API version number from libfabric:

       1. This code understands libfabric API versions v1.3 through
          v1.4.

       2. Open MPI may be *compiled* against one version of libfabric,
          but may be *running* with another.

       3. There were usnic-specific bugs in Libfabric prior to
          libfabric v1.3.0 (where "v1.3.0" is the tarball/package
          version, not the API version; but happily, the API version
          was also 1.3 in Libfabric v1.3.0):

          - In libfabric v1.0.0 (i.e., API v1.0), the usnic provider
            did not check the value of the "version" parameter passed
            into fi_getinfo()
          - If you pass FI_VERSION(1,0) to libfabric v1.1.0 (i.e., API
            v1.1), the usnic provider will disable FI_MSG_PREFIX
            support (on the assumption that the application will not
            handle FI_MSG_PREFIX properly).  This can happen if you
            compile OMPI against libfabric v1.0.0 (i.e., API v1.0) and
            run OMPI against libfabric v1.1.0 (i.e., API v1.1).
          - Some critical AV bug fixes were included in libfabric
            v1.3.0; prior versions can fail in fi_av_* operations in
            unexpected ways (libnl: you win again!).

       So always request a minimum API version of v1.3.

       Note that the FI_MAJOR_VERSION and FI_MINOR_VERSION in
       <rdma/fabric.h> represent the API version, not the Libfabric
       package (i.e., tarball) version.  As of Libfabric v1.3, there
       is currently no way to know a) what package version of
       Libfabric you were compiled against, and b) what package
       version of Libfabric you are running with.

       Also note that the usnic provider changed the strings in the
       fabric and domain names in API v1.4.  With API <= v1.3:

       - fabric name is "usnic_X" (device name)
       - domain name is NULL

       With libfabric API >= v1.4, all Libfabric IP-based providers
       (including usnic) follow the same convention:

       - fabric name is "a.b.c.d/e" (CIDR notation of network)
       - domain name is "usnic_X" (device name)

       NOTE: The configure.m4 in this component will require libfabric
       >= v1.1.0 (i.e., it won't accept v1.0.0) because it needs
       access to the usNIC extension header structures that only
       became available in v1.1.0.*/

    /* First, check to see if the libfabric we are running with is <=
       libfabric v1.3.  If so, don't bother going further. */
    uint32_t libfabric_api;
    libfabric_api = fi_version();
    if (libfabric_api < FI_VERSION(1, 3)) {
        opal_output_verbose(5, USNIC_OUT,
                            "btl:usnic: disqualifiying myself because Libfabric does not support v1.3 of the API (v1.3 is *required* for correct usNIC functionality).");
        return NULL;
    }

    /* Libfabric API 1.3 is fine.  Above that, we know that Open MPI
       works with libfabric API v1.4, so just use that. */
    if (libfabric_api > FI_VERSION(1, 3)) {
        libfabric_api = FI_VERSION(1, 4);
    }

    struct fi_info hints = {0};
    struct fi_ep_attr ep_attr = {0};
    struct fi_fabric_attr fabric_attr = {0};
    struct fi_rx_attr rx_attr = {0};
    struct fi_tx_attr tx_attr = {0};

    /* We only want providers named "usnic" that are of type EP_DGRAM */
    fabric_attr.prov_name = "usnic";
    ep_attr.type = FI_EP_DGRAM;

    hints.caps = FI_MSG;
    hints.mode = FI_LOCAL_MR | FI_MSG_PREFIX;
    hints.addr_format = FI_SOCKADDR;
    hints.ep_attr = &ep_attr;
    hints.fabric_attr = &fabric_attr;
    hints.tx_attr = &tx_attr;
    hints.rx_attr = &rx_attr;

    tx_attr.iov_limit = 1;
    rx_attr.iov_limit = 1;

    ret = fi_getinfo(libfabric_api, NULL, 0, 0, &hints, &info_list);
    if (0 != ret) {
        opal_output_verbose(5, USNIC_OUT,
                            "btl:usnic: disqualifiying myself due to fi_getinfo(3) failure: %s (%d)", strerror(-ret), ret);
        return NULL;
    }

    num_devs = 0;
    for (info = info_list; NULL != info; info = info->next) {
        ++num_devs;
    }
    if (0 == num_devs) {
        opal_output_verbose(5, USNIC_OUT,
            "btl:usnic: disqualifiying myself due to lack of libfabric providers");
        return NULL;
    }

    /* Do quick sanity check to ensure that we can lock memory (which
       is required for registered memory). */
    if (OPAL_SUCCESS != check_reg_mem_basics()) {
        opal_output_verbose(5, USNIC_OUT,
                            "btl:usnic: disqualifiying myself due to lack of lockable memory");
        return NULL;
    }

    /************************************************************************
     * Below this line, we assume that usnic is loaded on all procs,
     * and therefore we will guarantee to the the modex send, even if
     * we fail.
     ************************************************************************/

    opal_output_verbose(5, USNIC_OUT,
                        "btl:usnic: usNIC fabrics found");

    opal_proc_t *me = opal_proc_local_get();
    opal_process_name_t *name = &(me->proc_name);
    mca_btl_usnic_component.my_hashed_rte_name =
        usnic_compat_rte_hash_name(name);
    MSGDEBUG1_OUT("%s: my_hashed_rte_name=0x%" PRIx64,
                   __func__, mca_btl_usnic_component.my_hashed_rte_name);

    opal_srand(&opal_btl_usnic_rand_buff, ((uint32_t) getpid()));

    /* Setup an array of pointers to point to each module (which we'll
       return upstream) */
    mca_btl_usnic_component.num_modules = num_devs;
    btls = (struct mca_btl_base_module_t**)
        malloc(mca_btl_usnic_component.num_modules *
               sizeof(opal_btl_usnic_module_t*));
    if (NULL == btls) {
        OPAL_ERROR_LOG(OPAL_ERR_OUT_OF_RESOURCE);
        goto send_modex;
    }

    /* Allocate space for btl module instances */
    mca_btl_usnic_component.usnic_all_modules =
        calloc(mca_btl_usnic_component.num_modules,
               sizeof(*mca_btl_usnic_component.usnic_all_modules));
    mca_btl_usnic_component.usnic_active_modules =
        calloc(mca_btl_usnic_component.num_modules,
               sizeof(*mca_btl_usnic_component.usnic_active_modules));
    if (NULL == mca_btl_usnic_component.usnic_all_modules ||
        NULL == mca_btl_usnic_component.usnic_active_modules) {
        OPAL_ERROR_LOG(OPAL_ERR_OUT_OF_RESOURCE);
        goto error;
    }

    /* If we have include or exclude list, parse and set up now
     * (higher level guarantees there will not be both include and exclude,
     * so don't bother checking that here)
     */
    if (NULL != mca_btl_usnic_component.if_include) {
        opal_output_verbose(20, USNIC_OUT,
                            "btl:usnic:filter_module: if_include=%s",
                            mca_btl_usnic_component.if_include);

        filter_incl = true;
        filter = parse_ifex_str(mca_btl_usnic_component.if_include, "include");
    } else if (NULL != mca_btl_usnic_component.if_exclude) {
        opal_output_verbose(20, USNIC_OUT,
                            "btl:usnic:filter_module: if_exclude=%s",
                            mca_btl_usnic_component.if_exclude);

        filter_incl = false;
        filter = parse_ifex_str(mca_btl_usnic_component.if_exclude, "exclude");
    }

    num_local_procs = opal_process_info.num_local_peers;

    /* Go through the list of devices and determine if we want it or
       not.  Create a module for each one that we want. */
    info = info_list;
    for (j = i = 0; i < num_devs &&
             (0 == mca_btl_usnic_component.max_modules ||
              i < mca_btl_usnic_component.max_modules);
             ++i, info = info->next) {

        // The fabric/domain names changed at libfabric API v1.4 (see above).
        char *linux_device_name;
        if (libfabric_api <= FI_VERSION(1, 3)) {
            linux_device_name = info->fabric_attr->name;
        } else {
            linux_device_name = info->domain_attr->name;
        }

        ret = fi_fabric(info->fabric_attr, &fabric, NULL);
        if (0 != ret) {
            opal_show_help("help-mpi-btl-usnic.txt",
                           "libfabric API failed",
                           true,
                           opal_process_info.nodename,
                           linux_device_name,
                           "fi_fabric()", __FILE__, __LINE__,
                           ret,
                           strerror(-ret));
            continue;
        }
        opal_memchecker_base_mem_defined(&fabric, sizeof(fabric));

        ret = fi_domain(fabric, info, &domain, NULL);
        if (0 != ret) {
            opal_show_help("help-mpi-btl-usnic.txt",
                           "libfabric API failed",
                           true,
                           opal_process_info.nodename,
                           linux_device_name,
                           "fi_domain()", __FILE__, __LINE__,
                           ret,
                           strerror(-ret));
            continue;
        }
        opal_memchecker_base_mem_defined(&domain, sizeof(domain));

        opal_output_verbose(5, USNIC_OUT,
                            "btl:usnic: found: usNIC device %s",
                            linux_device_name);

        /* Save a little info on the module that we have already
           gathered.  The rest of the module will be filled in
           later. */
        module = &(mca_btl_usnic_component.usnic_all_modules[j]);
        memcpy(module, &opal_btl_usnic_module_template,
               sizeof(opal_btl_usnic_module_t));
        module->fabric = fabric;
        module->domain = domain;
        module->fabric_info = info;
        module->libfabric_api = libfabric_api;
        module->linux_device_name = strdup(linux_device_name);
        if (NULL == module->linux_device_name) {
            OPAL_ERROR_LOG(OPAL_ERR_OUT_OF_RESOURCE);
            goto error;
        }

        /* Obtain usnic-specific device info (e.g., netmask) that
           doesn't come in the normal fi_getinfo(). This allows us to
           do filtering, later. */
        ret = fi_open_ops(&fabric->fid, FI_USNIC_FABRIC_OPS_1, 0,
                (void **)&module->usnic_fabric_ops, NULL);
        if (ret != 0) {
            opal_output_verbose(5, USNIC_OUT,
                        "btl:usnic: device %s fabric_open_ops failed %d (%s)",
                        module->linux_device_name, ret, fi_strerror(-ret));
            fi_close(&domain->fid);
            fi_close(&fabric->fid);
            continue;
        }

        ret =
            module->usnic_fabric_ops->getinfo(1,
                                            fabric,
                                            &module->usnic_info);
        if (ret != 0) {
            opal_output_verbose(5, USNIC_OUT,
                        "btl:usnic: device %s usnic_getinfo failed %d (%s)",
                        module->linux_device_name, ret, fi_strerror(-ret));
            fi_close(&domain->fid);
            fi_close(&fabric->fid);
            continue;
        }
        opal_output_verbose(5, USNIC_OUT,
                            "btl:usnic: device %s usnic_info: link speed=%d, netmask=0x%x, ifname=%s, num_vf=%d, qp/vf=%d, cq/vf=%d",
                            module->linux_device_name,
                            (unsigned int) module->usnic_info.ui.v1.ui_link_speed,
                            (unsigned int) module->usnic_info.ui.v1.ui_netmask_be,
                            module->usnic_info.ui.v1.ui_ifname,
                            module->usnic_info.ui.v1.ui_num_vf,
                            module->usnic_info.ui.v1.ui_qp_per_vf,
                            module->usnic_info.ui.v1.ui_cq_per_vf);

        /* respect if_include/if_exclude subnets/ifaces from the user */
        if (filter != NULL) {
            keep_module = filter_module(module, filter, filter_incl);
            opal_output_verbose(5, USNIC_OUT,
                                "btl:usnic: %s %s due to %s",
                                (keep_module ? "keeping" : "skipping"),
                                module->linux_device_name,
                                (filter_incl ? "if_include" : "if_exclude"));
            if (!keep_module) {
                fi_close(&domain->fid);
                fi_close(&fabric->fid);
                continue;
            }
        }

        /* The first time through, check some usNIC configuration
           minimum settings with information we got back from the fi_*
           probes (these are VIC-wide settings -- they don't change
           for each module we create, so we only need to check
           once). */
        if (0 == j &&
            check_usnic_config(module, num_local_procs) != OPAL_SUCCESS) {
            opal_output_verbose(5, USNIC_OUT,
                                "btl:usnic: device %s is not provisioned with enough resources -- skipping",
                                module->linux_device_name);
            fi_close(&domain->fid);
            fi_close(&fabric->fid);

            mca_btl_usnic_component.num_modules = 0;
            goto error;
        }

        /*************************************************/
        /* Below this point, we know we want this device */
        /*************************************************/

        opal_output_verbose(5, USNIC_OUT,
                            "btl:usnic: device %s looks good!",
                            module->linux_device_name);

        /* Let this module advance to the next round! */
        btls[j++] = &(module->super);
    }
    mca_btl_usnic_component.num_modules = j;

    /* free filter if created */
    if (filter != NULL) {
        free_filter(filter);
        filter = NULL;
    }

    /* If we actually have some modules, setup the connectivity
       checking agent and client. */
    if (mca_btl_usnic_component.num_modules > 0 &&
        mca_btl_usnic_component.connectivity_enabled) {
        mca_btl_usnic_component.opal_evbase = opal_progress_thread_init(NULL);
        if (OPAL_SUCCESS != opal_btl_usnic_connectivity_agent_init() ||
            OPAL_SUCCESS != opal_btl_usnic_connectivity_client_init()) {
            opal_progress_thread_finalize(NULL);
            return NULL;
        }
    }

    /* Now that we know how many modules there are, let the modules
       initialize themselves (it's useful to know how many modules
       there are before doing this). */
    for (num_final_modules = i = 0;
         i < mca_btl_usnic_component.num_modules; ++i) {
        module = (opal_btl_usnic_module_t*) btls[i];

        /* Let the module initialize itself */
        if (OPAL_SUCCESS != opal_btl_usnic_module_init(module)) {
            opal_output_verbose(5, USNIC_OUT,
                                "btl:usnic: failed to init module for %s",
                                module->if_ipv4_addr_str);
            continue;
        }

        /*************************************************/
        /* Below this point, we know we want this module */
        /*************************************************/

        /* If module_init() failed for any prior module, this will be
           a down shift in the btls[] array.  Otherwise, it's an
           overwrite of the same value. */
        btls[num_final_modules++] = &(module->super);

        /* Output all of this module's values. */
        const char *devname = module->linux_device_name;
        opal_output_verbose(5, USNIC_OUT,
                            "btl:usnic: %s num sqe=%d, num rqe=%d, num cqe=%d, num aveqe=%d",
                            devname,
                            module->sd_num,
                            module->rd_num,
                            module->cq_num,
                            module->av_eq_num);
        opal_output_verbose(5, USNIC_OUT,
                            "btl:usnic: %s priority MTU = %" PRIsize_t,
                            devname,
                            module->max_tiny_msg_size);
        opal_output_verbose(5, USNIC_OUT,
                            "btl:usnic: %s priority limit = %" PRIsize_t,
                            devname,
                            module->max_tiny_payload);
        opal_output_verbose(5, USNIC_OUT,
                            "btl:usnic: %s eager limit = %" PRIsize_t,
                            devname,
                            module->super.btl_eager_limit);
        opal_output_verbose(5, USNIC_OUT,
                            "btl:usnic: %s eager rndv limit = %" PRIsize_t,
                            devname,
                            module->super.btl_rndv_eager_limit);
        opal_output_verbose(5, USNIC_OUT,
                            "btl:usnic: %s max send size= %" PRIsize_t
                            " (not overrideable)",
                            devname,
                            module->super.btl_max_send_size);
        opal_output_verbose(5, USNIC_OUT,
                            "btl:usnic: %s exclusivity = %d",
                            devname,
                            module->super.btl_exclusivity);
    }

    /* We may have skipped some modules, so reset
       component.num_modules */
    mca_btl_usnic_component.num_modules = num_final_modules;

    /* We've packed all the modules and pointers to those modules in
       the lower ends of their respective arrays.  If not all the
       modules initialized successfully, we're wasting a little space.
       We could realloc and re-form the btls[] array, but it doesn't
       seem worth it.  Just waste a little space.

       That being said, if we ended up with zero acceptable devices,
       then free everything. */
    if (0 == num_final_modules) {
        opal_output_verbose(5, USNIC_OUT,
                            "btl:usnic: returning 0 modules");
        goto error;
    }

    /* we have a nonzero number of modules, so save a copy of the btls array
     * for later use */
    memcpy(mca_btl_usnic_component.usnic_active_modules, btls,
           num_final_modules * sizeof(*btls));

    /* Loop over the modules and find the minimum value for
       module->numa_distance.  For every module that has a
       numa_distance higher than the minimum value, increase its btl
       latency rating so that the PML will prefer to send short
       messages over "near" modules. */
    min_distance = 9999999;
    for (i = 0; i < mca_btl_usnic_component.num_modules; ++i) {
        module = (opal_btl_usnic_module_t*) btls[i];
        if (module->numa_distance < min_distance) {
            min_distance = module->numa_distance;
        }
    }
    for (i = 0; i < mca_btl_usnic_component.num_modules; ++i) {
        module = (opal_btl_usnic_module_t*) btls[i];
        if (module->numa_distance > min_distance) {
            ++module->super.btl_latency;
            opal_output_verbose(5, USNIC_OUT,
                                "btl:usnic: %s is far from me; increasing latency rating",
                                module->if_ipv4_addr_str);
        }
    }

    /* start timer to guarantee synthetic clock advances */
    opal_event_set(opal_sync_event_base, &usnic_clock_timer_event,
                   -1, 0, usnic_clock_callback,
                   &usnic_clock_timeout);
    usnic_clock_timer_event_set = true;

    /* 1ms timer */
    usnic_clock_timeout.tv_sec = 0;
    usnic_clock_timeout.tv_usec = 1000;
    opal_event_add(&usnic_clock_timer_event, &usnic_clock_timeout);

    /* Setup MPI_T performance variables */
    opal_btl_usnic_setup_mpit_pvars();

    /* All done */
    *num_btl_modules = mca_btl_usnic_component.num_modules;
    opal_output_verbose(5, USNIC_OUT,
                        "btl:usnic: returning %d modules", *num_btl_modules);

 send_modex:
    usnic_modex_send();
    return btls;

 error:
    /* clean up as much allocated memory as possible */
    free(btls);
    btls = NULL;
    free(mca_btl_usnic_component.usnic_all_modules);
    mca_btl_usnic_component.usnic_all_modules = NULL;
    free(mca_btl_usnic_component.usnic_active_modules);
    mca_btl_usnic_component.usnic_active_modules = NULL;

    /* free filter if created */
    if (filter != NULL) {
        free_filter(filter);
        filter = NULL;
    }

    goto send_modex;
}

/*
 * Component progress
 * The fast-path of an incoming packet available on the priority
 * receive queue is handled directly in this routine, everything else
 * is deferred to an external call, usnic_component_progress_2()
 * This helps keep usnic_component_progress() very small and very responsive
 * to a single incoming packet.  We make sure not to always return
 * immediately after one packet to avoid starvation, "fastpath_ok" is
 * used for this.
 */
static int usnic_handle_completion(opal_btl_usnic_module_t* module,
    opal_btl_usnic_channel_t *channel, struct fi_cq_entry *completion);
static int usnic_component_progress_2(void);
static void usnic_handle_cq_error(opal_btl_usnic_module_t* module,
    opal_btl_usnic_channel_t *channel, int cq_ret);

static int usnic_component_progress(void)
{
    int i;
    int count;
    opal_btl_usnic_recv_segment_t* rseg;
    opal_btl_usnic_module_t* module;
    struct fi_cq_entry completion;
    opal_btl_usnic_channel_t *channel;
    static bool fastpath_ok = true;

    /* update our simulated clock */
    opal_btl_usnic_ticks += 5000;

    count = 0;
    if (fastpath_ok) {
        for (i = 0; i < mca_btl_usnic_component.num_modules; i++) {
            module = mca_btl_usnic_component.usnic_active_modules[i];
            channel = &module->mod_channels[USNIC_PRIORITY_CHANNEL];

            assert(channel->chan_deferred_recv == NULL);

            int ret = fi_cq_read(channel->cq, &completion, 1);
            assert(0 != ret);
            if (OPAL_LIKELY(1 == ret)) {
                opal_memchecker_base_mem_defined(&completion,
                                                 sizeof(completion));
                rseg = (opal_btl_usnic_recv_segment_t*) completion.op_context;
                if (OPAL_LIKELY(OPAL_BTL_USNIC_SEG_RECV ==
                            rseg->rs_base.us_type)) {
                    opal_btl_usnic_recv_fast(module, rseg, channel);
                    ++module->stats.num_seg_total_completions;
                    ++module->stats.num_seg_recv_completions;
                    fastpath_ok = false;    /* prevent starvation */
                    return 1;
                } else {
                    count += usnic_handle_completion(module, channel,
                                                     &completion);
                }
            } else if (OPAL_LIKELY(-FI_EAGAIN == ret)) {
                continue;
            } else {
                usnic_handle_cq_error(module, channel, ret);
            }
        }
    }

    fastpath_ok = true;
    return count + usnic_component_progress_2();
}

static int usnic_handle_completion(
    opal_btl_usnic_module_t* module,
    opal_btl_usnic_channel_t *channel,
    struct fi_cq_entry *completion)
{
    opal_btl_usnic_segment_t* seg;
    opal_btl_usnic_recv_segment_t* rseg;

    seg = (opal_btl_usnic_segment_t*)completion->op_context;
    rseg = (opal_btl_usnic_recv_segment_t*)seg;

    ++module->stats.num_seg_total_completions;

    /* Make the completion be Valgrind-defined */
    opal_memchecker_base_mem_defined(seg, sizeof(*seg));

    OPAL_THREAD_LOCK(&btl_usnic_lock);

    /* Handle work completions */
    switch(seg->us_type) {

    /**** Send ACK completions ****/
    case OPAL_BTL_USNIC_SEG_ACK:
        ++module->stats.num_seg_ack_completions;
        opal_btl_usnic_ack_complete(module,
                (opal_btl_usnic_ack_segment_t *)seg);
        break;

    /**** Send of frag segment completion (i.e., the MPI message's
          one-and-only segment has completed sending) ****/
    case OPAL_BTL_USNIC_SEG_FRAG:
        ++module->stats.num_seg_frag_completions;
        opal_btl_usnic_frag_send_complete(module,
                (opal_btl_usnic_frag_segment_t*)seg);
        break;

    /**** Send of chunk segment completion (i.e., part of a large MPI
          message is done sending) ****/
    case OPAL_BTL_USNIC_SEG_CHUNK:
        ++module->stats.num_seg_chunk_completions;
        opal_btl_usnic_chunk_send_complete(module,
                (opal_btl_usnic_chunk_segment_t*)seg);
        break;

    /**** Receive completions ****/
    case OPAL_BTL_USNIC_SEG_RECV:
        ++module->stats.num_seg_recv_completions;
        opal_btl_usnic_recv(module, rseg, channel);
        break;

    default:
        BTL_ERROR(("Unhandled completion segment type %d", seg->us_type));
        break;
    }

    OPAL_THREAD_UNLOCK(&btl_usnic_lock);
    return 1;
}

static void
usnic_handle_cq_error(opal_btl_usnic_module_t* module,
    opal_btl_usnic_channel_t *channel, int cq_ret)
{
    int rc;
    struct fi_cq_err_entry err_entry;
    opal_btl_usnic_recv_segment_t* rseg;

    if (cq_ret != -FI_EAVAIL) {
        BTL_ERROR(("%s: cq_read ret = %d (%s)",
               module->linux_device_name, cq_ret,
               fi_strerror(-cq_ret)));
        channel->chan_error = true;
    }

    rc = fi_cq_readerr(channel->cq, &err_entry, 0);
    if (rc == -FI_EAGAIN) {
        return;
    } else if (rc != 1) {
        BTL_ERROR(("%s: cq_readerr ret = %d (expected 1)",
                   module->linux_device_name, rc));
        channel->chan_error = true;
    }

    /* Silently count CRC errors.  Truncation errors are usually a
       different symptom of a CRC error. */
    else if (FI_ECRC == err_entry.prov_errno ||
             FI_ETRUNC == err_entry.prov_errno) {
#if MSGDEBUG1
        static int once = 0;
        if (once++ == 0) {
            BTL_ERROR(("%s: Channel %d, %s",
                       module->linux_device_name,
                       channel->chan_index,
                       FI_ECRC == err_entry.prov_errno ?
                       "CRC error" : "message truncation"));
        }
#endif

        /* silently count CRC errors */
        ++module->stats.num_crc_errors;

        /* repost segment */
        ++module->stats.num_recv_reposts;

        /* Add recv to linked list for reposting */
        rseg = err_entry.op_context;
        if (OPAL_BTL_USNIC_SEG_RECV == rseg->rs_base.us_type) {
            rseg->rs_next = channel->repost_recv_head;
            channel->repost_recv_head = rseg;
        }
    } else {
        BTL_ERROR(("%s: CQ[%d] prov_err = %d",
                   module->linux_device_name, channel->chan_index,
                   err_entry.prov_errno));
        channel->chan_error = true;
    }
}

static int usnic_component_progress_2(void)
{
    int i, j, count = 0, num_events, ret;
    opal_btl_usnic_module_t* module;
    static struct fi_cq_entry completions[OPAL_BTL_USNIC_NUM_COMPLETIONS];
    opal_btl_usnic_channel_t *channel;
    int rc;
    int c;

    /* update our simulated clock */
    opal_btl_usnic_ticks += 5000;

    /* Poll for completions */
    for (i = 0; i < mca_btl_usnic_component.num_modules; i++) {
        module = mca_btl_usnic_component.usnic_active_modules[i];

        /* poll each channel */
        for (c=0; c<USNIC_NUM_CHANNELS; ++c) {
            channel = &module->mod_channels[c];

            if (channel->chan_deferred_recv != NULL) {
                (void) opal_btl_usnic_recv_frag_bookkeeping(module,
                        channel->chan_deferred_recv, channel);
                channel->chan_deferred_recv = NULL;
            }

            num_events = ret =
                fi_cq_read(channel->cq, completions,
                           OPAL_BTL_USNIC_NUM_COMPLETIONS);
            assert(0 != ret);
            opal_memchecker_base_mem_defined(&ret, sizeof(ret));
            if (OPAL_UNLIKELY(ret < 0 && -FI_EAGAIN != ret)) {
                usnic_handle_cq_error(module, channel, num_events);
                num_events = 0;
            } else if (-FI_EAGAIN == ret) {
                num_events = 0;
            }

            opal_memchecker_base_mem_defined(completions,
                                             sizeof(completions[0]) *
                                             num_events);
            /* Handle each event */
            for (j = 0; j < num_events; j++) {
                count += usnic_handle_completion(module, channel,
                                                 &completions[j]);
            }

            /* return error if detected - this may be slightly deferred
             * since fastpath avoids the "if" of checking this.
             */
            if (channel->chan_error) {
                channel->chan_error = false;
                return OPAL_ERROR;
            }

            /* progress sends */
            opal_btl_usnic_module_progress_sends(module);

            /* Re-post all the remaining receive buffers */
            if (OPAL_LIKELY(NULL != channel->repost_recv_head)) {
                rc = opal_btl_usnic_post_recv_list(channel);
                if (OPAL_UNLIKELY(rc != 0)) {
                    BTL_ERROR(("error posting recv: %s\n", strerror(errno)));
                    return OPAL_ERROR;
                }
            }
        }
    }

    return count;
}

/* could take indent as a parameter instead of hard-coding it */
static void dump_endpoint(opal_btl_usnic_endpoint_t *endpoint)
{
    int i;
    opal_btl_usnic_frag_t *frag;
    opal_btl_usnic_send_segment_t *sseg;
    struct in_addr ia;
    char ep_addr_str[INET_ADDRSTRLEN];
    char tmp[128], str[2048];

    memset(ep_addr_str, 0x00, sizeof(ep_addr_str));
    ia.s_addr = endpoint->endpoint_remote_modex.ipv4_addr;
    inet_ntop(AF_INET, &ia, ep_addr_str, sizeof(ep_addr_str));

    opal_output(0, "    endpoint %p, %s job=%u, rank=%u rts=%s s_credits=%"PRIi32"\n",
                (void *)endpoint, ep_addr_str,
                endpoint->endpoint_proc->proc_opal->proc_name.jobid,
                endpoint->endpoint_proc->proc_opal->proc_name.vpid,
                (endpoint->endpoint_ready_to_send ? "true" : "false"),
                endpoint->endpoint_send_credits);
    opal_output(0, "      endpoint->frag_send_queue:\n");

    OPAL_LIST_FOREACH(frag, &endpoint->endpoint_frag_send_queue,
                      opal_btl_usnic_frag_t) {
        opal_btl_usnic_small_send_frag_t *ssfrag;
        opal_btl_usnic_large_send_frag_t *lsfrag;

        snprintf(str, sizeof(str), "      --> frag %p, %s", (void *)frag,
                 usnic_frag_type(frag->uf_type));
        switch (frag->uf_type) {
            case OPAL_BTL_USNIC_FRAG_LARGE_SEND:
                lsfrag = (opal_btl_usnic_large_send_frag_t *)frag;
                snprintf(tmp, sizeof(tmp), " tag=%"PRIu8" id=%"PRIu32" offset=%llu/%llu post_cnt=%"PRIu32" ack_bytes_left=%llu\n",
                        lsfrag->lsf_tag,
                        lsfrag->lsf_frag_id,
                        (unsigned long long)lsfrag->lsf_cur_offset,
                        (unsigned long long)lsfrag->lsf_base.sf_size,
                        lsfrag->lsf_base.sf_seg_post_cnt,
                        (unsigned long long)lsfrag->lsf_base.sf_ack_bytes_left);
                strncat(str, tmp, sizeof(str) - strlen(str) - 1);
                opal_output(0, "%s", str);

                OPAL_LIST_FOREACH(sseg, &lsfrag->lsf_seg_chain,
                                  opal_btl_usnic_send_segment_t) {
                    /* chunk segs are just typedefs to send segs */
                    opal_output(0, "        chunk seg %p, chan=%s hotel=%d times_posted=%"PRIu32" pending=%s\n",
                                (void *)sseg,
                                (USNIC_PRIORITY_CHANNEL == sseg->ss_channel ?
                                "prio" : "data"),
                                sseg->ss_hotel_room,
                                sseg->ss_send_posted,
                                (sseg->ss_ack_pending ? "true" : "false"));
                }
            break;

            case OPAL_BTL_USNIC_FRAG_SMALL_SEND:
                ssfrag = (opal_btl_usnic_small_send_frag_t *)frag;
                snprintf(tmp, sizeof(tmp), " sf_size=%llu post_cnt=%"PRIu32" ack_bytes_left=%llu\n",
                        (unsigned long long)ssfrag->ssf_base.sf_size,
                        ssfrag->ssf_base.sf_seg_post_cnt,
                        (unsigned long long)ssfrag->ssf_base.sf_ack_bytes_left);
                strncat(str, tmp, sizeof(str) - strlen(str) - 1);
                opal_output(0, "%s", str);

                sseg = &ssfrag->ssf_segment;
                opal_output(0, "        small seg %p, chan=%s hotel=%d times_posted=%"PRIu32" pending=%s\n",
                    (void *)sseg,
                    (USNIC_PRIORITY_CHANNEL == sseg->ss_channel ?
                        "prio" : "data"),
                    sseg->ss_hotel_room,
                    sseg->ss_send_posted,
                    (sseg->ss_ack_pending ? "true" : "false"));
            break;

            case OPAL_BTL_USNIC_FRAG_PUT_DEST:
                /* put_dest frags are just a typedef to generic frags */
                snprintf(tmp, sizeof(tmp), " put_addr=%p\n", frag->uf_remote_seg[0].seg_addr.pval);
                strncat(str, tmp, sizeof(str) - strlen(str) - 1);
                opal_output(0, "%s", str);
            break;
        }
    }

    /* Now examine the hotel for this endpoint and dump any segments we find
     * there.  Yes, this peeks at members that are technically "private", so
     * eventually this should be done through some sort of debug or iteration
     * interface in the hotel code. */
    opal_output(0, "      endpoint->endpoint_sent_segs (%p):\n",
           (void *)endpoint->endpoint_sent_segs);
    for (i = 0; i < WINDOW_SIZE; ++i) {
        sseg = endpoint->endpoint_sent_segs[i];
        if (NULL != sseg) {
            opal_output(0, "        [%d] sseg=%p %s chan=%s hotel=%d times_posted=%"PRIu32" pending=%s\n",
                   i,
                   (void *)sseg,
                   usnic_seg_type_str(sseg->ss_base.us_type),
                   (USNIC_PRIORITY_CHANNEL == sseg->ss_channel ?
                    "prio" : "data"),
                   sseg->ss_hotel_room,
                   sseg->ss_send_posted,
                   (sseg->ss_ack_pending ? "true" : "false"));
        }
    }

    opal_output(0, "      ack_needed=%s n_t=%"UDSEQ" n_a=%"UDSEQ" n_r=%"UDSEQ" n_s=%"UDSEQ" rfstart=%"PRIu32"\n",
                (endpoint->endpoint_ack_needed?"true":"false"),
                endpoint->endpoint_next_seq_to_send,
                endpoint->endpoint_ack_seq_rcvd,
                endpoint->endpoint_next_contig_seq_to_recv,
                endpoint->endpoint_highest_seq_rcvd,
                endpoint->endpoint_rfstart);

    if (dump_bitvectors) {
        opal_btl_usnic_snprintf_bool_array(str, sizeof(str),
                                           endpoint->endpoint_rcvd_segs,
                                           WINDOW_SIZE);
        opal_output(0, "      rcvd_segs 0x%s", str);
    }
}

void opal_btl_usnic_component_debug(void)
{
    int i;
    opal_btl_usnic_module_t *module;
    opal_btl_usnic_endpoint_t *endpoint;
    opal_btl_usnic_send_segment_t *sseg;
    opal_list_item_t *item;
    const opal_proc_t *proc = opal_proc_local_get();

    opal_output(0, "*** dumping usnic state for MPI_COMM_WORLD rank %u ***\n",
                proc->proc_name.vpid);
    for (i = 0; i < (int)mca_btl_usnic_component.num_modules; ++i) {
        module = mca_btl_usnic_component.usnic_active_modules[i];

        opal_output(0, "active_modules[%d]=%p %s max{frag,chunk,tiny}=%llu,%llu,%llu\n",
               i, (void *)module, module->linux_device_name,
               (unsigned long long)module->max_frag_payload,
               (unsigned long long)module->max_chunk_payload,
               (unsigned long long)module->max_tiny_payload);

        opal_output(0, "  endpoints_with_sends:\n");
        OPAL_LIST_FOREACH(endpoint, &module->endpoints_with_sends,
                          opal_btl_usnic_endpoint_t) {
            dump_endpoint(endpoint);
        }

        opal_output(0, "  endpoints_that_need_acks:\n");
        OPAL_LIST_FOREACH(endpoint, &module->endpoints_that_need_acks,
                          opal_btl_usnic_endpoint_t) {
            dump_endpoint(endpoint);
        }

        /* the all_endpoints list uses a different list item member */
        opal_output(0, "  all_endpoints:\n");
        opal_mutex_lock(&module->all_endpoints_lock);
        item = opal_list_get_first(&module->all_endpoints);
        while (item != opal_list_get_end(&module->all_endpoints)) {
            endpoint = container_of(item, mca_btl_base_endpoint_t,
                                    endpoint_endpoint_li);
            item = opal_list_get_next(item);
            dump_endpoint(endpoint);
        }
        opal_mutex_unlock(&module->all_endpoints_lock);

        opal_output(0, "  pending_resend_segs:\n");
        OPAL_LIST_FOREACH(sseg, &module->pending_resend_segs,
                          opal_btl_usnic_send_segment_t) {
            opal_output(0, "    sseg %p\n", (void *)sseg);
        }

        opal_btl_usnic_print_stats(module, "  manual", /*reset=*/false);
    }
}

#include "test/btl_usnic_component_test.h"
