/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.gnu.org/licenses/gpl-2.0.html
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2015, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * lnet/lnet/lib-move.c
 *
 * Data movement routines
 */

#define DEBUG_SUBSYSTEM S_LNET

#include "../../include/linux/lnet/lib-lnet.h"
#include <linux/nsproxy.h>
#include <net/net_namespace.h>

static int local_nid_dist_zero = 1;
module_param(local_nid_dist_zero, int, 0444);
MODULE_PARM_DESC(local_nid_dist_zero, "Reserved");

int
lnet_fail_nid(lnet_nid_t nid, unsigned int threshold)
{
        lnet_test_peer_t *tp;
        lnet_test_peer_t *temp;
        struct list_head *el;
        struct list_head *next;
        struct list_head cull;

        /* NB: use lnet_net_lock(0) to serialize operations on test peers */
        if (threshold) {
                /* Adding a new entry */
                LIBCFS_ALLOC(tp, sizeof(*tp));
                if (!tp)
                        return -ENOMEM;

                tp->tp_nid = nid;
                tp->tp_threshold = threshold;

                lnet_net_lock(0);
                list_add_tail(&tp->tp_list, &the_lnet.ln_test_peers);
                lnet_net_unlock(0);
                return 0;
        }

        /* removing entries */
        INIT_LIST_HEAD(&cull);

        lnet_net_lock(0);

        list_for_each_safe(el, next, &the_lnet.ln_test_peers) {
                tp = list_entry(el, lnet_test_peer_t, tp_list);

                if (!tp->tp_threshold ||    /* needs culling anyway */
                    nid == LNET_NID_ANY ||       /* removing all entries */
                    tp->tp_nid == nid) {          /* matched this one */
                        list_del(&tp->tp_list);
                        list_add(&tp->tp_list, &cull);
                }
        }

        lnet_net_unlock(0);

        list_for_each_entry_safe(tp, temp, &cull, tp_list) {
                list_del(&tp->tp_list);
                LIBCFS_FREE(tp, sizeof(*tp));
        }
        return 0;
}

static int
fail_peer(lnet_nid_t nid, int outgoing)
{
        lnet_test_peer_t *tp;
        lnet_test_peer_t *temp;
        struct list_head *el;
        struct list_head *next;
        struct list_head cull;
        int fail = 0;

        INIT_LIST_HEAD(&cull);

        /* NB: use lnet_net_lock(0) to serialize operations on test peers */
        lnet_net_lock(0);

        list_for_each_safe(el, next, &the_lnet.ln_test_peers) {
                tp = list_entry(el, lnet_test_peer_t, tp_list);

                if (!tp->tp_threshold) {
                        /* zombie entry */
                        if (outgoing) {
                                /*
                                 * only cull zombies on outgoing tests,
                                 * since we may be at interrupt priority on
                                 * incoming messages.
                                 */
                                list_del(&tp->tp_list);
                                list_add(&tp->tp_list, &cull);
                        }
                        continue;
                }

                if (tp->tp_nid == LNET_NID_ANY || /* fail every peer */
                    nid == tp->tp_nid) {        /* fail this peer */
                        fail = 1;

                        if (tp->tp_threshold != LNET_MD_THRESH_INF) {
                                tp->tp_threshold--;
                                if (outgoing &&
                                    !tp->tp_threshold) {
                                        /* see above */
                                        list_del(&tp->tp_list);
                                        list_add(&tp->tp_list, &cull);
                                }
                        }
                        break;
                }
        }

        lnet_net_unlock(0);

        list_for_each_entry_safe(tp, temp, &cull, tp_list) {
                list_del(&tp->tp_list);

                LIBCFS_FREE(tp, sizeof(*tp));
        }

        return fail;
}

unsigned int
lnet_iov_nob(unsigned int niov, struct kvec *iov)
{
        unsigned int nob = 0;

        LASSERT(!niov || iov);
        while (niov-- > 0)
                nob += (iov++)->iov_len;

        return nob;
}
EXPORT_SYMBOL(lnet_iov_nob);

void
lnet_copy_iov2iter(struct iov_iter *to,
                   unsigned int nsiov, const struct kvec *siov,
                   unsigned int soffset, unsigned int nob)
{
        /* NB diov, siov are READ-ONLY */
        const char *s;
        size_t left;

        if (!nob)
                return;

        /* skip complete frags before 'soffset' */
        LASSERT(nsiov > 0);
        while (soffset >= siov->iov_len) {
                soffset -= siov->iov_len;
                siov++;
                nsiov--;
                LASSERT(nsiov > 0);
        }

        s = (char *)siov->iov_base + soffset;
        left = siov->iov_len - soffset;
        do {
                size_t n, copy = left;

                LASSERT(nsiov > 0);

                if (copy > nob)
                        copy = nob;
                n = copy_to_iter(s, copy, to);
                if (n != copy)
                        return;
                nob -= n;

                siov++;
                s = (char *)siov->iov_base;
                left = siov->iov_len;
                nsiov--;
        } while (nob > 0);
}
EXPORT_SYMBOL(lnet_copy_iov2iter);

void
lnet_copy_kiov2iter(struct iov_iter *to,
                    unsigned int nsiov, const lnet_kiov_t *siov,
                    unsigned int soffset, unsigned int nob)
{
        if (!nob)
                return;

        LASSERT(!in_interrupt());

        LASSERT(nsiov > 0);
        while (soffset >= siov->bv_len) {
                soffset -= siov->bv_len;
                siov++;
                nsiov--;
                LASSERT(nsiov > 0);
        }

        do {
                size_t copy = siov->bv_len - soffset, n;

                LASSERT(nsiov > 0);

                if (copy > nob)
                        copy = nob;
                n = copy_page_to_iter(siov->bv_page,
                                      siov->bv_offset + soffset,
                                      copy, to);
                if (n != copy)
                        return;
                nob -= n;
                siov++;
                nsiov--;
                soffset = 0;
        } while (nob > 0);
}
EXPORT_SYMBOL(lnet_copy_kiov2iter);

int
lnet_extract_iov(int dst_niov, struct kvec *dst,
                 int src_niov, const struct kvec *src,
                 unsigned int offset, unsigned int len)
{
        /*
         * Initialise 'dst' to the subset of 'src' starting at 'offset',
         * for exactly 'len' bytes, and return the number of entries.
         * NB not destructive to 'src'
         */
        unsigned int frag_len;
        unsigned int niov;

        if (!len)                          /* no data => */
                return 0;                    /* no frags */

        LASSERT(src_niov > 0);
        while (offset >= src->iov_len) {      /* skip initial frags */
                offset -= src->iov_len;
                src_niov--;
                src++;
                LASSERT(src_niov > 0);
        }

        niov = 1;
        for (;;) {
                LASSERT(src_niov > 0);
                LASSERT((int)niov <= dst_niov);

                frag_len = src->iov_len - offset;
                dst->iov_base = ((char *)src->iov_base) + offset;

                if (len <= frag_len) {
                        dst->iov_len = len;
                        return niov;
                }

                dst->iov_len = frag_len;

                len -= frag_len;
                dst++;
                src++;
                niov++;
                src_niov--;
                offset = 0;
        }
}
EXPORT_SYMBOL(lnet_extract_iov);

unsigned int
lnet_kiov_nob(unsigned int niov, lnet_kiov_t *kiov)
{
        unsigned int nob = 0;

        LASSERT(!niov || kiov);
        while (niov-- > 0)
                nob += (kiov++)->bv_len;

        return nob;
}
EXPORT_SYMBOL(lnet_kiov_nob);

int
lnet_extract_kiov(int dst_niov, lnet_kiov_t *dst,
                  int src_niov, const lnet_kiov_t *src,
                  unsigned int offset, unsigned int len)
{
        /*
         * Initialise 'dst' to the subset of 'src' starting at 'offset',
         * for exactly 'len' bytes, and return the number of entries.
         * NB not destructive to 'src'
         */
        unsigned int frag_len;
        unsigned int niov;

        if (!len)                          /* no data => */
                return 0;                    /* no frags */

        LASSERT(src_niov > 0);
        while (offset >= src->bv_len) {      /* skip initial frags */
                offset -= src->bv_len;
                src_niov--;
                src++;
                LASSERT(src_niov > 0);
        }

        niov = 1;
        for (;;) {
                LASSERT(src_niov > 0);
                LASSERT((int)niov <= dst_niov);

                frag_len = src->bv_len - offset;
                dst->bv_page = src->bv_page;
                dst->bv_offset = src->bv_offset + offset;

                if (len <= frag_len) {
                        dst->bv_len = len;
                        LASSERT(dst->bv_offset + dst->bv_len
                                        <= PAGE_SIZE);
                        return niov;
                }

                dst->bv_len = frag_len;
                LASSERT(dst->bv_offset + dst->bv_len <= PAGE_SIZE);

                len -= frag_len;
                dst++;
                src++;
                niov++;
                src_niov--;
                offset = 0;
        }
}
EXPORT_SYMBOL(lnet_extract_kiov);

void
lnet_ni_recv(lnet_ni_t *ni, void *private, lnet_msg_t *msg, int delayed,
             unsigned int offset, unsigned int mlen, unsigned int rlen)
{
        unsigned int niov = 0;
        struct kvec *iov = NULL;
        lnet_kiov_t *kiov = NULL;
        struct iov_iter to;
        int rc;

        LASSERT(!in_interrupt());
        LASSERT(!mlen || msg);

        if (msg) {
                LASSERT(msg->msg_receiving);
                LASSERT(!msg->msg_sending);
                LASSERT(rlen == msg->msg_len);
                LASSERT(mlen <= msg->msg_len);
                LASSERT(msg->msg_offset == offset);
                LASSERT(msg->msg_wanted == mlen);

                msg->msg_receiving = 0;

                if (mlen) {
                        niov = msg->msg_niov;
                        iov  = msg->msg_iov;
                        kiov = msg->msg_kiov;

                        LASSERT(niov > 0);
                        LASSERT(!iov != !kiov);
                }
        }

        if (iov) {
                iov_iter_kvec(&to, ITER_KVEC | READ, iov, niov, mlen + offset);
                iov_iter_advance(&to, offset);
        } else {
                iov_iter_bvec(&to, ITER_BVEC | READ, kiov, niov, mlen + offset);
                iov_iter_advance(&to, offset);
        }
        rc = ni->ni_lnd->lnd_recv(ni, private, msg, delayed, &to, rlen);
        if (rc < 0)
                lnet_finalize(ni, msg, rc);
}

static void
lnet_setpayloadbuffer(lnet_msg_t *msg)
{
        lnet_libmd_t *md = msg->msg_md;

        LASSERT(msg->msg_len > 0);
        LASSERT(!msg->msg_routing);
        LASSERT(md);
        LASSERT(!msg->msg_niov);
        LASSERT(!msg->msg_iov);
        LASSERT(!msg->msg_kiov);

        msg->msg_niov = md->md_niov;
        if (md->md_options & LNET_MD_KIOV)
                msg->msg_kiov = md->md_iov.kiov;
        else
                msg->msg_iov = md->md_iov.iov;
}

void
lnet_prep_send(lnet_msg_t *msg, int type, lnet_process_id_t target,
               unsigned int offset, unsigned int len)
{
        msg->msg_type = type;
        msg->msg_target = target;
        msg->msg_len = len;
        msg->msg_offset = offset;

        if (len)
                lnet_setpayloadbuffer(msg);

        memset(&msg->msg_hdr, 0, sizeof(msg->msg_hdr));
        msg->msg_hdr.type          = cpu_to_le32(type);
        msg->msg_hdr.dest_nid       = cpu_to_le64(target.nid);
        msg->msg_hdr.dest_pid       = cpu_to_le32(target.pid);
        /* src_nid will be set later */
        msg->msg_hdr.src_pid    = cpu_to_le32(the_lnet.ln_pid);
        msg->msg_hdr.payload_length = cpu_to_le32(len);
}

static void
lnet_ni_send(lnet_ni_t *ni, lnet_msg_t *msg)
{
        void *priv = msg->msg_private;
        int rc;

        LASSERT(!in_interrupt());
        LASSERT(LNET_NETTYP(LNET_NIDNET(ni->ni_nid)) == LOLND ||
                (msg->msg_txcredit && msg->msg_peertxcredit));

        rc = ni->ni_lnd->lnd_send(ni, priv, msg);
        if (rc < 0)
                lnet_finalize(ni, msg, rc);
}

static int
lnet_ni_eager_recv(lnet_ni_t *ni, lnet_msg_t *msg)
{
        int rc;

        LASSERT(!msg->msg_sending);
        LASSERT(msg->msg_receiving);
        LASSERT(!msg->msg_rx_ready_delay);
        LASSERT(ni->ni_lnd->lnd_eager_recv);

        msg->msg_rx_ready_delay = 1;
        rc = ni->ni_lnd->lnd_eager_recv(ni, msg->msg_private, msg,
                                        &msg->msg_private);
        if (rc) {
                CERROR("recv from %s / send to %s aborted: eager_recv failed %d\n",
                       libcfs_nid2str(msg->msg_rxpeer->lp_nid),
                       libcfs_id2str(msg->msg_target), rc);
                LASSERT(rc < 0); /* required by my callers */
        }

        return rc;
}

/* NB: caller shall hold a ref on 'lp' as I'd drop lnet_net_lock */
static void
lnet_ni_query_locked(lnet_ni_t *ni, lnet_peer_t *lp)
{
        unsigned long last_alive = 0;

        LASSERT(lnet_peer_aliveness_enabled(lp));
        LASSERT(ni->ni_lnd->lnd_query);

        lnet_net_unlock(lp->lp_cpt);
        ni->ni_lnd->lnd_query(ni, lp->lp_nid, &last_alive);
        lnet_net_lock(lp->lp_cpt);

        lp->lp_last_query = cfs_time_current();

        if (last_alive) /* NI has updated timestamp */
                lp->lp_last_alive = last_alive;
}

/* NB: always called with lnet_net_lock held */
static inline int
lnet_peer_is_alive(lnet_peer_t *lp, unsigned long now)
{
        int alive;
        unsigned long deadline;

        LASSERT(lnet_peer_aliveness_enabled(lp));

        /* Trust lnet_notify() if it has more recent aliveness news, but
         * ignore the initial assumed death (see lnet_peers_start_down()).
         */
        if (!lp->lp_alive && lp->lp_alive_count > 0 &&
            cfs_time_aftereq(lp->lp_timestamp, lp->lp_last_alive))
                return 0;

        deadline = cfs_time_add(lp->lp_last_alive,
                                cfs_time_seconds(lp->lp_ni->ni_peertimeout));
        alive = cfs_time_after(deadline, now);

        /* Update obsolete lp_alive except for routers assumed to be dead
         * initially, because router checker would update aliveness in this
         * case, and moreover lp_last_alive at peer creation is assumed.
         */
        if (alive && !lp->lp_alive &&
            !(lnet_isrouter(lp) && !lp->lp_alive_count))
                lnet_notify_locked(lp, 0, 1, lp->lp_last_alive);

        return alive;
}

/*
 * NB: returns 1 when alive, 0 when dead, negative when error;
 *     may drop the lnet_net_lock
 */
static int
lnet_peer_alive_locked(lnet_peer_t *lp)
{
        unsigned long now = cfs_time_current();

        if (!lnet_peer_aliveness_enabled(lp))
                return -ENODEV;

        if (lnet_peer_is_alive(lp, now))
                return 1;

        /*
         * Peer appears dead, but we should avoid frequent NI queries (at
         * most once per lnet_queryinterval seconds).
         */
        if (lp->lp_last_query) {
                static const int lnet_queryinterval = 1;

                unsigned long next_query =
                           cfs_time_add(lp->lp_last_query,
                                        cfs_time_seconds(lnet_queryinterval));

                if (time_before(now, next_query)) {
                        if (lp->lp_alive)
                                CWARN("Unexpected aliveness of peer %s: %d < %d (%d/%d)\n",
                                      libcfs_nid2str(lp->lp_nid),
                                      (int)now, (int)next_query,
                                      lnet_queryinterval,
                                      lp->lp_ni->ni_peertimeout);
                        return 0;
                }
        }

        /* query NI for latest aliveness news */
        lnet_ni_query_locked(lp->lp_ni, lp);

        if (lnet_peer_is_alive(lp, now))
                return 1;

        lnet_notify_locked(lp, 0, 0, lp->lp_last_alive);
        return 0;
}

/**
 * \param msg The message to be sent.
 * \param do_send True if lnet_ni_send() should be called in this function.
 *        lnet_send() is going to lnet_net_unlock immediately after this, so
 *        it sets do_send FALSE and I don't do the unlock/send/lock bit.
 *
 * \retval LNET_CREDIT_OK If \a msg sent or OK to send.
 * \retval LNET_CREDIT_WAIT If \a msg blocked for credit.
 * \retval -EHOSTUNREACH If the next hop of the message appears dead.
 * \retval -ECANCELED If the MD of the message has been unlinked.
 */
static int
lnet_post_send_locked(lnet_msg_t *msg, int do_send)
{
        lnet_peer_t *lp = msg->msg_txpeer;
        lnet_ni_t *ni = lp->lp_ni;
        int cpt = msg->msg_tx_cpt;
        struct lnet_tx_queue *tq = ni->ni_tx_queues[cpt];

        /* non-lnet_send() callers have checked before */
        LASSERT(!do_send || msg->msg_tx_delayed);
        LASSERT(!msg->msg_receiving);
        LASSERT(msg->msg_tx_committed);

        /* NB 'lp' is always the next hop */
        if (!(msg->msg_target.pid & LNET_PID_USERFLAG) &&
            !lnet_peer_alive_locked(lp)) {
                the_lnet.ln_counters[cpt]->drop_count++;
                the_lnet.ln_counters[cpt]->drop_length += msg->msg_len;
                lnet_net_unlock(cpt);

                CNETERR("Dropping message for %s: peer not alive\n",
                        libcfs_id2str(msg->msg_target));
                if (do_send)
                        lnet_finalize(ni, msg, -EHOSTUNREACH);

                lnet_net_lock(cpt);
                return -EHOSTUNREACH;
        }

        if (msg->msg_md &&
            (msg->msg_md->md_flags & LNET_MD_FLAG_ABORTED)) {
                lnet_net_unlock(cpt);

                CNETERR("Aborting message for %s: LNetM[DE]Unlink() already called on the MD/ME.\n",
                        libcfs_id2str(msg->msg_target));
                if (do_send)
                        lnet_finalize(ni, msg, -ECANCELED);

                lnet_net_lock(cpt);
                return -ECANCELED;
        }

        if (!msg->msg_peertxcredit) {
                LASSERT((lp->lp_txcredits < 0) ==
                        !list_empty(&lp->lp_txq));

                msg->msg_peertxcredit = 1;
                lp->lp_txqnob += msg->msg_len + sizeof(lnet_hdr_t);
                lp->lp_txcredits--;

                if (lp->lp_txcredits < lp->lp_mintxcredits)
                        lp->lp_mintxcredits = lp->lp_txcredits;

                if (lp->lp_txcredits < 0) {
                        msg->msg_tx_delayed = 1;
                        list_add_tail(&msg->msg_list, &lp->lp_txq);
                        return LNET_CREDIT_WAIT;
                }
        }

        if (!msg->msg_txcredit) {
                LASSERT((tq->tq_credits < 0) ==
                        !list_empty(&tq->tq_delayed));

                msg->msg_txcredit = 1;
                tq->tq_credits--;

                if (tq->tq_credits < tq->tq_credits_min)
                        tq->tq_credits_min = tq->tq_credits;

                if (tq->tq_credits < 0) {
                        msg->msg_tx_delayed = 1;
                        list_add_tail(&msg->msg_list, &tq->tq_delayed);
                        return LNET_CREDIT_WAIT;
                }
        }

        if (do_send) {
                lnet_net_unlock(cpt);
                lnet_ni_send(ni, msg);
                lnet_net_lock(cpt);
        }
        return LNET_CREDIT_OK;
}

static lnet_rtrbufpool_t *
lnet_msg2bufpool(lnet_msg_t *msg)
{
        lnet_rtrbufpool_t *rbp;
        int cpt;

        LASSERT(msg->msg_rx_committed);

        cpt = msg->msg_rx_cpt;
        rbp = &the_lnet.ln_rtrpools[cpt][0];

        LASSERT(msg->msg_len <= LNET_MTU);
        while (msg->msg_len > (unsigned int)rbp->rbp_npages * PAGE_SIZE) {
                rbp++;
                LASSERT(rbp < &the_lnet.ln_rtrpools[cpt][LNET_NRBPOOLS]);
        }

        return rbp;
}

static int
lnet_post_routed_recv_locked(lnet_msg_t *msg, int do_recv)
{
        /*
         * lnet_parse is going to lnet_net_unlock immediately after this, so it
         * sets do_recv FALSE and I don't do the unlock/send/lock bit.
         * I return LNET_CREDIT_WAIT if msg blocked and LNET_CREDIT_OK if
         * received or OK to receive
         */
        lnet_peer_t *lp = msg->msg_rxpeer;
        lnet_rtrbufpool_t *rbp;
        lnet_rtrbuf_t *rb;

        LASSERT(!msg->msg_iov);
        LASSERT(!msg->msg_kiov);
        LASSERT(!msg->msg_niov);
        LASSERT(msg->msg_routing);
        LASSERT(msg->msg_receiving);
        LASSERT(!msg->msg_sending);

        /* non-lnet_parse callers only receive delayed messages */
        LASSERT(!do_recv || msg->msg_rx_delayed);

        if (!msg->msg_peerrtrcredit) {
                LASSERT((lp->lp_rtrcredits < 0) ==
                        !list_empty(&lp->lp_rtrq));

                msg->msg_peerrtrcredit = 1;
                lp->lp_rtrcredits--;
                if (lp->lp_rtrcredits < lp->lp_minrtrcredits)
                        lp->lp_minrtrcredits = lp->lp_rtrcredits;

                if (lp->lp_rtrcredits < 0) {
                        /* must have checked eager_recv before here */
                        LASSERT(msg->msg_rx_ready_delay);
                        msg->msg_rx_delayed = 1;
                        list_add_tail(&msg->msg_list, &lp->lp_rtrq);
                        return LNET_CREDIT_WAIT;
                }
        }

        rbp = lnet_msg2bufpool(msg);

        if (!msg->msg_rtrcredit) {
                msg->msg_rtrcredit = 1;
                rbp->rbp_credits--;
                if (rbp->rbp_credits < rbp->rbp_mincredits)
                        rbp->rbp_mincredits = rbp->rbp_credits;

                if (rbp->rbp_credits < 0) {
                        /* must have checked eager_recv before here */
                        LASSERT(msg->msg_rx_ready_delay);
                        msg->msg_rx_delayed = 1;
                        list_add_tail(&msg->msg_list, &rbp->rbp_msgs);
                        return LNET_CREDIT_WAIT;
                }
        }

        LASSERT(!list_empty(&rbp->rbp_bufs));
        rb = list_entry(rbp->rbp_bufs.next, lnet_rtrbuf_t, rb_list);
        list_del(&rb->rb_list);

        msg->msg_niov = rbp->rbp_npages;
        msg->msg_kiov = &rb->rb_kiov[0];

        if (do_recv) {
                int cpt = msg->msg_rx_cpt;

                lnet_net_unlock(cpt);
                lnet_ni_recv(lp->lp_ni, msg->msg_private, msg, 1,
                             0, msg->msg_len, msg->msg_len);
                lnet_net_lock(cpt);
        }
        return LNET_CREDIT_OK;
}

void
lnet_return_tx_credits_locked(lnet_msg_t *msg)
{
        lnet_peer_t *txpeer = msg->msg_txpeer;
        lnet_msg_t *msg2;

        if (msg->msg_txcredit) {
                struct lnet_ni *ni = txpeer->lp_ni;
                struct lnet_tx_queue *tq = ni->ni_tx_queues[msg->msg_tx_cpt];

                /* give back NI txcredits */
                msg->msg_txcredit = 0;

                LASSERT((tq->tq_credits < 0) ==
                        !list_empty(&tq->tq_delayed));

                tq->tq_credits++;
                if (tq->tq_credits <= 0) {
                        msg2 = list_entry(tq->tq_delayed.next,
                                          lnet_msg_t, msg_list);
                        list_del(&msg2->msg_list);

                        LASSERT(msg2->msg_txpeer->lp_ni == ni);
                        LASSERT(msg2->msg_tx_delayed);

                        (void)lnet_post_send_locked(msg2, 1);
                }
        }

        if (msg->msg_peertxcredit) {
                /* give back peer txcredits */
                msg->msg_peertxcredit = 0;

                LASSERT((txpeer->lp_txcredits < 0) ==
                        !list_empty(&txpeer->lp_txq));

                txpeer->lp_txqnob -= msg->msg_len + sizeof(lnet_hdr_t);
                LASSERT(txpeer->lp_txqnob >= 0);

                txpeer->lp_txcredits++;
                if (txpeer->lp_txcredits <= 0) {
                        msg2 = list_entry(txpeer->lp_txq.next,
                                          lnet_msg_t, msg_list);
                        list_del(&msg2->msg_list);

                        LASSERT(msg2->msg_txpeer == txpeer);
                        LASSERT(msg2->msg_tx_delayed);

                        (void)lnet_post_send_locked(msg2, 1);
                }
        }

        if (txpeer) {
                msg->msg_txpeer = NULL;
                lnet_peer_decref_locked(txpeer);
        }
}

void
lnet_schedule_blocked_locked(lnet_rtrbufpool_t *rbp)
{
        lnet_msg_t *msg;

        if (list_empty(&rbp->rbp_msgs))
                return;
        msg = list_entry(rbp->rbp_msgs.next,
                         lnet_msg_t, msg_list);
        list_del(&msg->msg_list);

        (void)lnet_post_routed_recv_locked(msg, 1);
}

void
lnet_drop_routed_msgs_locked(struct list_head *list, int cpt)
{
        struct list_head drop;
        lnet_msg_t *msg;
        lnet_msg_t *tmp;

        INIT_LIST_HEAD(&drop);

        list_splice_init(list, &drop);

        lnet_net_unlock(cpt);

        list_for_each_entry_safe(msg, tmp, &drop, msg_list) {
                lnet_ni_recv(msg->msg_rxpeer->lp_ni, msg->msg_private, NULL,
                             0, 0, 0, msg->msg_hdr.payload_length);
                list_del_init(&msg->msg_list);
                lnet_finalize(NULL, msg, -ECANCELED);
        }

        lnet_net_lock(cpt);
}

void
lnet_return_rx_credits_locked(lnet_msg_t *msg)
{
        lnet_peer_t *rxpeer = msg->msg_rxpeer;
        lnet_msg_t *msg2;

        if (msg->msg_rtrcredit) {
                /* give back global router credits */
                lnet_rtrbuf_t *rb;
                lnet_rtrbufpool_t *rbp;

                /*
                 * NB If a msg ever blocks for a buffer in rbp_msgs, it stays
                 * there until it gets one allocated, or aborts the wait
                 * itself
                 */
                LASSERT(msg->msg_kiov);

                rb = list_entry(msg->msg_kiov, lnet_rtrbuf_t, rb_kiov[0]);
                rbp = rb->rb_pool;

                msg->msg_kiov = NULL;
                msg->msg_rtrcredit = 0;

                LASSERT(rbp == lnet_msg2bufpool(msg));

                LASSERT((rbp->rbp_credits > 0) ==
                        !list_empty(&rbp->rbp_bufs));

                /*
                 * If routing is now turned off, we just drop this buffer and
                 * don't bother trying to return credits.
                 */
                if (!the_lnet.ln_routing) {
                        lnet_destroy_rtrbuf(rb, rbp->rbp_npages);
                        goto routing_off;
                }

                /*
                 * It is possible that a user has lowered the desired number of
                 * buffers in this pool.  Make sure we never put back
                 * more buffers than the stated number.
                 */
                if (unlikely(rbp->rbp_credits >= rbp->rbp_req_nbuffers)) {
                        /* Discard this buffer so we don't have too many. */
                        lnet_destroy_rtrbuf(rb, rbp->rbp_npages);
                        rbp->rbp_nbuffers--;
                } else {
                        list_add(&rb->rb_list, &rbp->rbp_bufs);
                        rbp->rbp_credits++;
                        if (rbp->rbp_credits <= 0)
                                lnet_schedule_blocked_locked(rbp);
                }
        }

routing_off:
        if (msg->msg_peerrtrcredit) {
                /* give back peer router credits */
                msg->msg_peerrtrcredit = 0;

                LASSERT((rxpeer->lp_rtrcredits < 0) ==
                        !list_empty(&rxpeer->lp_rtrq));

                rxpeer->lp_rtrcredits++;
                /*
                 * drop all messages which are queued to be routed on that
                 * peer.
                 */
                if (!the_lnet.ln_routing) {
                        lnet_drop_routed_msgs_locked(&rxpeer->lp_rtrq,
                                                     msg->msg_rx_cpt);
                } else if (rxpeer->lp_rtrcredits <= 0) {
                        msg2 = list_entry(rxpeer->lp_rtrq.next,
                                          lnet_msg_t, msg_list);
                        list_del(&msg2->msg_list);

                        (void)lnet_post_routed_recv_locked(msg2, 1);
                }
        }
        if (rxpeer) {
                msg->msg_rxpeer = NULL;
                lnet_peer_decref_locked(rxpeer);
        }
}

static int
lnet_compare_routes(lnet_route_t *r1, lnet_route_t *r2)
{
        lnet_peer_t *p1 = r1->lr_gateway;
        lnet_peer_t *p2 = r2->lr_gateway;
        int r1_hops = (r1->lr_hops == LNET_UNDEFINED_HOPS) ? 1 : r1->lr_hops;
        int r2_hops = (r2->lr_hops == LNET_UNDEFINED_HOPS) ? 1 : r2->lr_hops;

        if (r1->lr_priority < r2->lr_priority)
                return 1;

        if (r1->lr_priority > r2->lr_priority)
                return -ERANGE;

        if (r1_hops < r2_hops)
                return 1;

        if (r1_hops > r2_hops)
                return -ERANGE;

        if (p1->lp_txqnob < p2->lp_txqnob)
                return 1;

        if (p1->lp_txqnob > p2->lp_txqnob)
                return -ERANGE;

        if (p1->lp_txcredits > p2->lp_txcredits)
                return 1;

        if (p1->lp_txcredits < p2->lp_txcredits)
                return -ERANGE;

        if (r1->lr_seq - r2->lr_seq <= 0)
                return 1;

        return -ERANGE;
}

static lnet_peer_t *
lnet_find_route_locked(lnet_ni_t *ni, lnet_nid_t target, lnet_nid_t rtr_nid)
{
        lnet_remotenet_t *rnet;
        lnet_route_t *route;

        lnet_route_t *best_route;
        lnet_route_t *last_route;
        struct lnet_peer *lp_best;
        struct lnet_peer *lp;
        int rc;

        /*
         * If @rtr_nid is not LNET_NID_ANY, return the gateway with
         * rtr_nid nid, otherwise find the best gateway I can use
         */
        rnet = lnet_find_net_locked(LNET_NIDNET(target));
        if (!rnet)
                return NULL;

        lp_best = NULL;
        best_route = NULL;
        last_route = NULL;
        list_for_each_entry(route, &rnet->lrn_routes, lr_list) {
                lp = route->lr_gateway;

                if (!lnet_is_route_alive(route))
                        continue;

                if (ni && lp->lp_ni != ni)
                        continue;

                if (lp->lp_nid == rtr_nid) /* it's pre-determined router */
                        return lp;

                if (!lp_best) {
                        best_route = route;
                        last_route = route;
                        lp_best = lp;
                        continue;
                }

                /* no protection on below fields, but it's harmless */
                if (last_route->lr_seq - route->lr_seq < 0)
                        last_route = route;

                rc = lnet_compare_routes(route, best_route);
                if (rc < 0)
                        continue;

                best_route = route;
                lp_best = lp;
        }

        /*
         * set sequence number on the best router to the latest sequence + 1
         * so we can round-robin all routers, it's race and inaccurate but
         * harmless and functional
         */
        if (best_route)
                best_route->lr_seq = last_route->lr_seq + 1;
        return lp_best;
}

int
lnet_send(lnet_nid_t src_nid, lnet_msg_t *msg, lnet_nid_t rtr_nid)
{
        lnet_nid_t dst_nid = msg->msg_target.nid;
        struct lnet_ni *src_ni;
        struct lnet_ni *local_ni;
        struct lnet_peer *lp;
        int cpt;
        int cpt2;
        int rc;

        /*
         * NB: rtr_nid is set to LNET_NID_ANY for all current use-cases,
         * but we might want to use pre-determined router for ACK/REPLY
         * in the future
         */
        /* NB: ni == interface pre-determined (ACK/REPLY) */
        LASSERT(!msg->msg_txpeer);
        LASSERT(!msg->msg_sending);
        LASSERT(!msg->msg_target_is_router);
        LASSERT(!msg->msg_receiving);

        msg->msg_sending = 1;

        LASSERT(!msg->msg_tx_committed);
        cpt = lnet_cpt_of_nid(rtr_nid == LNET_NID_ANY ? dst_nid : rtr_nid);
 again:
        lnet_net_lock(cpt);

        if (the_lnet.ln_shutdown) {
                lnet_net_unlock(cpt);
                return -ESHUTDOWN;
        }

        if (src_nid == LNET_NID_ANY) {
                src_ni = NULL;
        } else {
                src_ni = lnet_nid2ni_locked(src_nid, cpt);
                if (!src_ni) {
                        lnet_net_unlock(cpt);
                        LCONSOLE_WARN("Can't send to %s: src %s is not a local nid\n",
                                      libcfs_nid2str(dst_nid),
                                      libcfs_nid2str(src_nid));
                        return -EINVAL;
                }
                LASSERT(!msg->msg_routing);
        }

        /* Is this for someone on a local network? */
        local_ni = lnet_net2ni_locked(LNET_NIDNET(dst_nid), cpt);

        if (local_ni) {
                if (!src_ni) {
                        src_ni = local_ni;
                        src_nid = src_ni->ni_nid;
                } else if (src_ni == local_ni) {
                        lnet_ni_decref_locked(local_ni, cpt);
                } else {
                        lnet_ni_decref_locked(local_ni, cpt);
                        lnet_ni_decref_locked(src_ni, cpt);
                        lnet_net_unlock(cpt);
                        LCONSOLE_WARN("No route to %s via from %s\n",
                                      libcfs_nid2str(dst_nid),
                                      libcfs_nid2str(src_nid));
                        return -EINVAL;
                }

                LASSERT(src_nid != LNET_NID_ANY);
                lnet_msg_commit(msg, cpt);

                if (!msg->msg_routing)
                        msg->msg_hdr.src_nid = cpu_to_le64(src_nid);

                if (src_ni == the_lnet.ln_loni) {
                        /* No send credit hassles with LOLND */
                        lnet_net_unlock(cpt);
                        lnet_ni_send(src_ni, msg);

                        lnet_net_lock(cpt);
                        lnet_ni_decref_locked(src_ni, cpt);
                        lnet_net_unlock(cpt);
                        return 0;
                }

                rc = lnet_nid2peer_locked(&lp, dst_nid, cpt);
                /* lp has ref on src_ni; lose mine */
                lnet_ni_decref_locked(src_ni, cpt);
                if (rc) {
                        lnet_net_unlock(cpt);
                        LCONSOLE_WARN("Error %d finding peer %s\n", rc,
                                      libcfs_nid2str(dst_nid));
                        /* ENOMEM or shutting down */
                        return rc;
                }
                LASSERT(lp->lp_ni == src_ni);
        } else {
                /* sending to a remote network */
                lp = lnet_find_route_locked(src_ni, dst_nid, rtr_nid);
                if (!lp) {
                        if (src_ni)
                                lnet_ni_decref_locked(src_ni, cpt);
                        lnet_net_unlock(cpt);

                        LCONSOLE_WARN("No route to %s via %s (all routers down)\n",
                                      libcfs_id2str(msg->msg_target),
                                      libcfs_nid2str(src_nid));
                        return -EHOSTUNREACH;
                }

                /*
                 * rtr_nid is LNET_NID_ANY or NID of pre-determined router,
                 * it's possible that rtr_nid isn't LNET_NID_ANY and lp isn't
                 * pre-determined router, this can happen if router table
                 * was changed when we release the lock
                 */
                if (rtr_nid != lp->lp_nid) {
                        cpt2 = lnet_cpt_of_nid_locked(lp->lp_nid);
                        if (cpt2 != cpt) {
                                if (src_ni)
                                        lnet_ni_decref_locked(src_ni, cpt);
                                lnet_net_unlock(cpt);

                                rtr_nid = lp->lp_nid;
                                cpt = cpt2;
                                goto again;
                        }
                }

                CDEBUG(D_NET, "Best route to %s via %s for %s %d\n",
                       libcfs_nid2str(dst_nid), libcfs_nid2str(lp->lp_nid),
                       lnet_msgtyp2str(msg->msg_type), msg->msg_len);

                if (!src_ni) {
                        src_ni = lp->lp_ni;
                        src_nid = src_ni->ni_nid;
                } else {
                        LASSERT(src_ni == lp->lp_ni);
                        lnet_ni_decref_locked(src_ni, cpt);
                }

                lnet_peer_addref_locked(lp);

                LASSERT(src_nid != LNET_NID_ANY);
                lnet_msg_commit(msg, cpt);

                if (!msg->msg_routing) {
                        /* I'm the source and now I know which NI to send on */
                        msg->msg_hdr.src_nid = cpu_to_le64(src_nid);
                }

                msg->msg_target_is_router = 1;
                msg->msg_target.nid = lp->lp_nid;
                msg->msg_target.pid = LNET_PID_LUSTRE;
        }

        /* 'lp' is our best choice of peer */

        LASSERT(!msg->msg_peertxcredit);
        LASSERT(!msg->msg_txcredit);
        LASSERT(!msg->msg_txpeer);

        msg->msg_txpeer = lp;              /* msg takes my ref on lp */

        rc = lnet_post_send_locked(msg, 0);
        lnet_net_unlock(cpt);

        if (rc < 0)
                return rc;

        if (rc == LNET_CREDIT_OK)
                lnet_ni_send(src_ni, msg);

        return 0; /* rc == LNET_CREDIT_OK or LNET_CREDIT_WAIT */
}

void
lnet_drop_message(lnet_ni_t *ni, int cpt, void *private, unsigned int nob)
{
        lnet_net_lock(cpt);
        the_lnet.ln_counters[cpt]->drop_count++;
        the_lnet.ln_counters[cpt]->drop_length += nob;
        lnet_net_unlock(cpt);

        lnet_ni_recv(ni, private, NULL, 0, 0, 0, nob);
}

static void
lnet_recv_put(lnet_ni_t *ni, lnet_msg_t *msg)
{
        lnet_hdr_t *hdr = &msg->msg_hdr;

        if (msg->msg_wanted)
                lnet_setpayloadbuffer(msg);

        lnet_build_msg_event(msg, LNET_EVENT_PUT);

        /*
         * Must I ACK?  If so I'll grab the ack_wmd out of the header and put
         * it back into the ACK during lnet_finalize()
         */
        msg->msg_ack = !lnet_is_wire_handle_none(&hdr->msg.put.ack_wmd) &&
                       !(msg->msg_md->md_options & LNET_MD_ACK_DISABLE);

        lnet_ni_recv(ni, msg->msg_private, msg, msg->msg_rx_delayed,
                     msg->msg_offset, msg->msg_wanted, hdr->payload_length);
}

static int
lnet_parse_put(lnet_ni_t *ni, lnet_msg_t *msg)
{
        lnet_hdr_t *hdr = &msg->msg_hdr;
        struct lnet_match_info info;
        bool ready_delay;
        int rc;

        /* Convert put fields to host byte order */
        hdr->msg.put.match_bits = le64_to_cpu(hdr->msg.put.match_bits);
        hdr->msg.put.ptl_index  = le32_to_cpu(hdr->msg.put.ptl_index);
        hdr->msg.put.offset     = le32_to_cpu(hdr->msg.put.offset);

        info.mi_id.nid  = hdr->src_nid;
        info.mi_id.pid  = hdr->src_pid;
        info.mi_opc     = LNET_MD_OP_PUT;
        info.mi_portal  = hdr->msg.put.ptl_index;
        info.mi_rlength = hdr->payload_length;
        info.mi_roffset = hdr->msg.put.offset;
        info.mi_mbits   = hdr->msg.put.match_bits;

        msg->msg_rx_ready_delay = !ni->ni_lnd->lnd_eager_recv;
        ready_delay = msg->msg_rx_ready_delay;

 again:
        rc = lnet_ptl_match_md(&info, msg);
        switch (rc) {
        default:
                LBUG();

        case LNET_MATCHMD_OK:
                lnet_recv_put(ni, msg);
                return 0;

        case LNET_MATCHMD_NONE:
                /**
                 * no eager_recv or has already called it, should
                 * have been attached on delayed list
                 */
                if (ready_delay)
                        return 0;

                rc = lnet_ni_eager_recv(ni, msg);
                if (!rc) {
                        ready_delay = true;
                        goto again;
                }
                /* fall through */

        case LNET_MATCHMD_DROP:
                CNETERR("Dropping PUT from %s portal %d match %llu offset %d length %d: %d\n",
                        libcfs_id2str(info.mi_id), info.mi_portal,
                        info.mi_mbits, info.mi_roffset, info.mi_rlength, rc);

                return -ENOENT; /* -ve: OK but no match */
        }
}

static int
lnet_parse_get(lnet_ni_t *ni, lnet_msg_t *msg, int rdma_get)
{
        struct lnet_match_info info;
        lnet_hdr_t *hdr = &msg->msg_hdr;
        lnet_handle_wire_t reply_wmd;
        int rc;

        /* Convert get fields to host byte order */
        hdr->msg.get.match_bits  = le64_to_cpu(hdr->msg.get.match_bits);
        hdr->msg.get.ptl_index   = le32_to_cpu(hdr->msg.get.ptl_index);
        hdr->msg.get.sink_length = le32_to_cpu(hdr->msg.get.sink_length);
        hdr->msg.get.src_offset  = le32_to_cpu(hdr->msg.get.src_offset);

        info.mi_id.nid  = hdr->src_nid;
        info.mi_id.pid  = hdr->src_pid;
        info.mi_opc     = LNET_MD_OP_GET;
        info.mi_portal  = hdr->msg.get.ptl_index;
        info.mi_rlength = hdr->msg.get.sink_length;
        info.mi_roffset = hdr->msg.get.src_offset;
        info.mi_mbits   = hdr->msg.get.match_bits;

        rc = lnet_ptl_match_md(&info, msg);
        if (rc == LNET_MATCHMD_DROP) {
                CNETERR("Dropping GET from %s portal %d match %llu offset %d length %d\n",
                        libcfs_id2str(info.mi_id), info.mi_portal,
                        info.mi_mbits, info.mi_roffset, info.mi_rlength);
                return -ENOENT; /* -ve: OK but no match */
        }

        LASSERT(rc == LNET_MATCHMD_OK);

        lnet_build_msg_event(msg, LNET_EVENT_GET);

        reply_wmd = hdr->msg.get.return_wmd;

        lnet_prep_send(msg, LNET_MSG_REPLY, info.mi_id,
                       msg->msg_offset, msg->msg_wanted);

        msg->msg_hdr.msg.reply.dst_wmd = reply_wmd;

        if (rdma_get) {
                /* The LND completes the REPLY from her recv procedure */
                lnet_ni_recv(ni, msg->msg_private, msg, 0,
                             msg->msg_offset, msg->msg_len, msg->msg_len);
                return 0;
        }

        lnet_ni_recv(ni, msg->msg_private, NULL, 0, 0, 0, 0);
        msg->msg_receiving = 0;

        rc = lnet_send(ni->ni_nid, msg, LNET_NID_ANY);
        if (rc < 0) {
                /* didn't get as far as lnet_ni_send() */
                CERROR("%s: Unable to send REPLY for GET from %s: %d\n",
                       libcfs_nid2str(ni->ni_nid),
                       libcfs_id2str(info.mi_id), rc);

                lnet_finalize(ni, msg, rc);
        }

        return 0;
}

static int
lnet_parse_reply(lnet_ni_t *ni, lnet_msg_t *msg)
{
        void *private = msg->msg_private;
        lnet_hdr_t *hdr = &msg->msg_hdr;
        lnet_process_id_t src = {0};
        lnet_libmd_t *md;
        int rlength;
        int mlength;
        int cpt;

        cpt = lnet_cpt_of_cookie(hdr->msg.reply.dst_wmd.wh_object_cookie);
        lnet_res_lock(cpt);

        src.nid = hdr->src_nid;
        src.pid = hdr->src_pid;

        /* NB handles only looked up by creator (no flips) */
        md = lnet_wire_handle2md(&hdr->msg.reply.dst_wmd);
        if (!md || !md->md_threshold || md->md_me) {
                CNETERR("%s: Dropping REPLY from %s for %s MD %#llx.%#llx\n",
                        libcfs_nid2str(ni->ni_nid), libcfs_id2str(src),
                        !md ? "invalid" : "inactive",
                        hdr->msg.reply.dst_wmd.wh_interface_cookie,
                        hdr->msg.reply.dst_wmd.wh_object_cookie);
                if (md && md->md_me)
                        CERROR("REPLY MD also attached to portal %d\n",
                               md->md_me->me_portal);

                lnet_res_unlock(cpt);
                return -ENOENT; /* -ve: OK but no match */
        }

        LASSERT(!md->md_offset);

        rlength = hdr->payload_length;
        mlength = min_t(uint, rlength, md->md_length);

        if (mlength < rlength &&
            !(md->md_options & LNET_MD_TRUNCATE)) {
                CNETERR("%s: Dropping REPLY from %s length %d for MD %#llx would overflow (%d)\n",
                        libcfs_nid2str(ni->ni_nid), libcfs_id2str(src),
                        rlength, hdr->msg.reply.dst_wmd.wh_object_cookie,
                        mlength);
                lnet_res_unlock(cpt);
                return -ENOENT; /* -ve: OK but no match */
        }

        CDEBUG(D_NET, "%s: Reply from %s of length %d/%d into md %#llx\n",
               libcfs_nid2str(ni->ni_nid), libcfs_id2str(src),
               mlength, rlength, hdr->msg.reply.dst_wmd.wh_object_cookie);

        lnet_msg_attach_md(msg, md, 0, mlength);

        if (mlength)
                lnet_setpayloadbuffer(msg);

        lnet_res_unlock(cpt);

        lnet_build_msg_event(msg, LNET_EVENT_REPLY);

        lnet_ni_recv(ni, private, msg, 0, 0, mlength, rlength);
        return 0;
}

static int
lnet_parse_ack(lnet_ni_t *ni, lnet_msg_t *msg)
{
        lnet_hdr_t *hdr = &msg->msg_hdr;
        lnet_process_id_t src = {0};
        lnet_libmd_t *md;
        int cpt;

        src.nid = hdr->src_nid;
        src.pid = hdr->src_pid;

        /* Convert ack fields to host byte order */
        hdr->msg.ack.match_bits = le64_to_cpu(hdr->msg.ack.match_bits);
        hdr->msg.ack.mlength = le32_to_cpu(hdr->msg.ack.mlength);

        cpt = lnet_cpt_of_cookie(hdr->msg.ack.dst_wmd.wh_object_cookie);
        lnet_res_lock(cpt);

        /* NB handles only looked up by creator (no flips) */
        md = lnet_wire_handle2md(&hdr->msg.ack.dst_wmd);
        if (!md || !md->md_threshold || md->md_me) {
                /* Don't moan; this is expected */
                CDEBUG(D_NET,
                       "%s: Dropping ACK from %s to %s MD %#llx.%#llx\n",
                       libcfs_nid2str(ni->ni_nid), libcfs_id2str(src),
                       !md ? "invalid" : "inactive",
                       hdr->msg.ack.dst_wmd.wh_interface_cookie,
                       hdr->msg.ack.dst_wmd.wh_object_cookie);
                if (md && md->md_me)
                        CERROR("Source MD also attached to portal %d\n",
                               md->md_me->me_portal);

                lnet_res_unlock(cpt);
                return -ENOENT; /* -ve! */
        }

        CDEBUG(D_NET, "%s: ACK from %s into md %#llx\n",
               libcfs_nid2str(ni->ni_nid), libcfs_id2str(src),
               hdr->msg.ack.dst_wmd.wh_object_cookie);

        lnet_msg_attach_md(msg, md, 0, 0);

        lnet_res_unlock(cpt);

        lnet_build_msg_event(msg, LNET_EVENT_ACK);

        lnet_ni_recv(ni, msg->msg_private, msg, 0, 0, 0, msg->msg_len);
        return 0;
}

/**
 * \retval LNET_CREDIT_OK       If \a msg is forwarded
 * \retval LNET_CREDIT_WAIT     If \a msg is blocked because w/o buffer
 * \retval -ve                  error code
 */
int
lnet_parse_forward_locked(lnet_ni_t *ni, lnet_msg_t *msg)
{
        int rc = 0;

        if (!the_lnet.ln_routing)
                return -ECANCELED;

        if (msg->msg_rxpeer->lp_rtrcredits <= 0 ||
            lnet_msg2bufpool(msg)->rbp_credits <= 0) {
                if (!ni->ni_lnd->lnd_eager_recv) {
                        msg->msg_rx_ready_delay = 1;
                } else {
                        lnet_net_unlock(msg->msg_rx_cpt);
                        rc = lnet_ni_eager_recv(ni, msg);
                        lnet_net_lock(msg->msg_rx_cpt);
                }
        }

        if (!rc)
                rc = lnet_post_routed_recv_locked(msg, 0);
        return rc;
}

int
lnet_parse_local(lnet_ni_t *ni, lnet_msg_t *msg)
{
        int rc;

        switch (msg->msg_type) {
        case LNET_MSG_ACK:
                rc = lnet_parse_ack(ni, msg);
                break;
        case LNET_MSG_PUT:
                rc = lnet_parse_put(ni, msg);
                break;
        case LNET_MSG_GET:
                rc = lnet_parse_get(ni, msg, msg->msg_rdma_get);
                break;
        case LNET_MSG_REPLY:
                rc = lnet_parse_reply(ni, msg);
                break;
        default: /* prevent an unused label if !kernel */
                LASSERT(0);
                return -EPROTO;
        }

        LASSERT(!rc || rc == -ENOENT);
        return rc;
}

char *
lnet_msgtyp2str(int type)
{
        switch (type) {
        case LNET_MSG_ACK:
                return "ACK";
        case LNET_MSG_PUT:
                return "PUT";
        case LNET_MSG_GET:
                return "GET";
        case LNET_MSG_REPLY:
                return "REPLY";
        case LNET_MSG_HELLO:
                return "HELLO";
        default:
                return "<UNKNOWN>";
        }
}

void
lnet_print_hdr(lnet_hdr_t *hdr)
{
        lnet_process_id_t src = {0};
        lnet_process_id_t dst = {0};
        char *type_str = lnet_msgtyp2str(hdr->type);

        src.nid = hdr->src_nid;
        src.pid = hdr->src_pid;

        dst.nid = hdr->dest_nid;
        dst.pid = hdr->dest_pid;

        CWARN("P3 Header at %p of type %s\n", hdr, type_str);
        CWARN("    From %s\n", libcfs_id2str(src));
        CWARN("    To   %s\n", libcfs_id2str(dst));

        switch (hdr->type) {
        default:
                break;

        case LNET_MSG_PUT:
                CWARN("    Ptl index %d, ack md %#llx.%#llx, match bits %llu\n",
                      hdr->msg.put.ptl_index,
                      hdr->msg.put.ack_wmd.wh_interface_cookie,
                      hdr->msg.put.ack_wmd.wh_object_cookie,
                      hdr->msg.put.match_bits);
                CWARN("    Length %d, offset %d, hdr data %#llx\n",
                      hdr->payload_length, hdr->msg.put.offset,
                      hdr->msg.put.hdr_data);
                break;

        case LNET_MSG_GET:
                CWARN("    Ptl index %d, return md %#llx.%#llx, match bits %llu\n",
                      hdr->msg.get.ptl_index,
                      hdr->msg.get.return_wmd.wh_interface_cookie,
                      hdr->msg.get.return_wmd.wh_object_cookie,
                      hdr->msg.get.match_bits);
                CWARN("    Length %d, src offset %d\n",
                      hdr->msg.get.sink_length,
                      hdr->msg.get.src_offset);
                break;

        case LNET_MSG_ACK:
                CWARN("    dst md %#llx.%#llx, manipulated length %d\n",
                      hdr->msg.ack.dst_wmd.wh_interface_cookie,
                      hdr->msg.ack.dst_wmd.wh_object_cookie,
                      hdr->msg.ack.mlength);
                break;

        case LNET_MSG_REPLY:
                CWARN("    dst md %#llx.%#llx, length %d\n",
                      hdr->msg.reply.dst_wmd.wh_interface_cookie,
                      hdr->msg.reply.dst_wmd.wh_object_cookie,
                      hdr->payload_length);
        }
}

int
lnet_parse(lnet_ni_t *ni, lnet_hdr_t *hdr, lnet_nid_t from_nid,
           void *private, int rdma_req)
{
        int rc = 0;
        int cpt;
        int for_me;
        struct lnet_msg *msg;
        lnet_pid_t dest_pid;
        lnet_nid_t dest_nid;
        lnet_nid_t src_nid;
        __u32 payload_length;
        __u32 type;

        LASSERT(!in_interrupt());

        type = le32_to_cpu(hdr->type);
        src_nid = le64_to_cpu(hdr->src_nid);
        dest_nid = le64_to_cpu(hdr->dest_nid);
        dest_pid = le32_to_cpu(hdr->dest_pid);
        payload_length = le32_to_cpu(hdr->payload_length);

        for_me = (ni->ni_nid == dest_nid);
        cpt = lnet_cpt_of_nid(from_nid);

        switch (type) {
        case LNET_MSG_ACK:
        case LNET_MSG_GET:
                if (payload_length > 0) {
                        CERROR("%s, src %s: bad %s payload %d (0 expected)\n",
                               libcfs_nid2str(from_nid),
                               libcfs_nid2str(src_nid),
                               lnet_msgtyp2str(type), payload_length);
                        return -EPROTO;
                }
                break;

        case LNET_MSG_PUT:
        case LNET_MSG_REPLY:
                if (payload_length >
                   (__u32)(for_me ? LNET_MAX_PAYLOAD : LNET_MTU)) {
                        CERROR("%s, src %s: bad %s payload %d (%d max expected)\n",
                               libcfs_nid2str(from_nid),
                               libcfs_nid2str(src_nid),
                               lnet_msgtyp2str(type),
                               payload_length,
                               for_me ? LNET_MAX_PAYLOAD : LNET_MTU);
                        return -EPROTO;
                }
                break;

        default:
                CERROR("%s, src %s: Bad message type 0x%x\n",
                       libcfs_nid2str(from_nid),
                       libcfs_nid2str(src_nid), type);
                return -EPROTO;
        }

        if (the_lnet.ln_routing &&
            ni->ni_last_alive != ktime_get_real_seconds()) {
                /* NB: so far here is the only place to set NI status to "up */
                lnet_ni_lock(ni);
                ni->ni_last_alive = ktime_get_real_seconds();
                if (ni->ni_status &&
                    ni->ni_status->ns_status == LNET_NI_STATUS_DOWN)
                        ni->ni_status->ns_status = LNET_NI_STATUS_UP;
                lnet_ni_unlock(ni);
        }

        /*
         * Regard a bad destination NID as a protocol error.  Senders should
         * know what they're doing; if they don't they're misconfigured, buggy
         * or malicious so we chop them off at the knees :)
         */
        if (!for_me) {
                if (LNET_NIDNET(dest_nid) == LNET_NIDNET(ni->ni_nid)) {
                        /* should have gone direct */
                        CERROR("%s, src %s: Bad dest nid %s (should have been sent direct)\n",
                               libcfs_nid2str(from_nid),
                               libcfs_nid2str(src_nid),
                               libcfs_nid2str(dest_nid));
                        return -EPROTO;
                }

                if (lnet_islocalnid(dest_nid)) {
                        /*
                         * dest is another local NI; sender should have used
                         * this node's NID on its own network
                         */
                        CERROR("%s, src %s: Bad dest nid %s (it's my nid but on a different network)\n",
                               libcfs_nid2str(from_nid),
                               libcfs_nid2str(src_nid),
                               libcfs_nid2str(dest_nid));
                        return -EPROTO;
                }

                if (rdma_req && type == LNET_MSG_GET) {
                        CERROR("%s, src %s: Bad optimized GET for %s (final destination must be me)\n",
                               libcfs_nid2str(from_nid),
                               libcfs_nid2str(src_nid),
                               libcfs_nid2str(dest_nid));
                        return -EPROTO;
                }

                if (!the_lnet.ln_routing) {
                        CERROR("%s, src %s: Dropping message for %s (routing not enabled)\n",
                               libcfs_nid2str(from_nid),
                               libcfs_nid2str(src_nid),
                               libcfs_nid2str(dest_nid));
                        goto drop;
                }
        }

        /*
         * Message looks OK; we're not going to return an error, so we MUST
         * call back lnd_recv() come what may...
         */
        if (!list_empty(&the_lnet.ln_test_peers) && /* normally we don't */
            fail_peer(src_nid, 0)) {         /* shall we now? */
                CERROR("%s, src %s: Dropping %s to simulate failure\n",
                       libcfs_nid2str(from_nid), libcfs_nid2str(src_nid),
                       lnet_msgtyp2str(type));
                goto drop;
        }

        if (!list_empty(&the_lnet.ln_drop_rules) &&
            lnet_drop_rule_match(hdr)) {
                CDEBUG(D_NET, "%s, src %s, dst %s: Dropping %s to simulate silent message loss\n",
                       libcfs_nid2str(from_nid), libcfs_nid2str(src_nid),
                       libcfs_nid2str(dest_nid), lnet_msgtyp2str(type));
                goto drop;
        }

        msg = lnet_msg_alloc();
        if (!msg) {
                CERROR("%s, src %s: Dropping %s (out of memory)\n",
                       libcfs_nid2str(from_nid), libcfs_nid2str(src_nid),
                       lnet_msgtyp2str(type));
                goto drop;
        }

        /* msg zeroed in lnet_msg_alloc;
         * i.e. flags all clear, pointers NULL etc
         */
        msg->msg_type = type;
        msg->msg_private = private;
        msg->msg_receiving = 1;
        msg->msg_rdma_get = rdma_req;
        msg->msg_wanted = payload_length;
        msg->msg_len = payload_length;
        msg->msg_offset = 0;
        msg->msg_hdr = *hdr;
        /* for building message event */
        msg->msg_from = from_nid;
        if (!for_me) {
                msg->msg_target.pid     = dest_pid;
                msg->msg_target.nid     = dest_nid;
                msg->msg_routing        = 1;

        } else {
                /* convert common msg->hdr fields to host byteorder */
                msg->msg_hdr.type       = type;
                msg->msg_hdr.src_nid    = src_nid;
                msg->msg_hdr.src_pid    = le32_to_cpu(msg->msg_hdr.src_pid);
                msg->msg_hdr.dest_nid   = dest_nid;
                msg->msg_hdr.dest_pid   = dest_pid;
                msg->msg_hdr.payload_length = payload_length;
        }

        lnet_net_lock(cpt);
        rc = lnet_nid2peer_locked(&msg->msg_rxpeer, from_nid, cpt);
        if (rc) {
                lnet_net_unlock(cpt);
                CERROR("%s, src %s: Dropping %s (error %d looking up sender)\n",
                       libcfs_nid2str(from_nid), libcfs_nid2str(src_nid),
                       lnet_msgtyp2str(type), rc);
                lnet_msg_free(msg);
                if (rc == -ESHUTDOWN)
                        /* We are shutting down. Don't do anything more */
                        return 0;
                goto drop;
        }

        if (lnet_isrouter(msg->msg_rxpeer)) {
                lnet_peer_set_alive(msg->msg_rxpeer);
                if (avoid_asym_router_failure &&
                    LNET_NIDNET(src_nid) != LNET_NIDNET(from_nid)) {
                        /* received a remote message from router, update
                         * remote NI status on this router.
                         * NB: multi-hop routed message will be ignored.
                         */
                        lnet_router_ni_update_locked(msg->msg_rxpeer,
                                                     LNET_NIDNET(src_nid));
                }
        }

        lnet_msg_commit(msg, cpt);

        /* message delay simulation */
        if (unlikely(!list_empty(&the_lnet.ln_delay_rules) &&
                     lnet_delay_rule_match_locked(hdr, msg))) {
                lnet_net_unlock(cpt);
                return 0;
        }

        if (!for_me) {
                rc = lnet_parse_forward_locked(ni, msg);
                lnet_net_unlock(cpt);

                if (rc < 0)
                        goto free_drop;

                if (rc == LNET_CREDIT_OK) {
                        lnet_ni_recv(ni, msg->msg_private, msg, 0,
                                     0, payload_length, payload_length);
                }
                return 0;
        }

        lnet_net_unlock(cpt);

        rc = lnet_parse_local(ni, msg);
        if (rc)
                goto free_drop;
        return 0;

 free_drop:
        LASSERT(!msg->msg_md);
        lnet_finalize(ni, msg, rc);

 drop:
        lnet_drop_message(ni, cpt, private, payload_length);
        return 0;
}
EXPORT_SYMBOL(lnet_parse);

void
lnet_drop_delayed_msg_list(struct list_head *head, char *reason)
{
        while (!list_empty(head)) {
                lnet_process_id_t id = {0};
                lnet_msg_t *msg;

                msg = list_entry(head->next, lnet_msg_t, msg_list);
                list_del(&msg->msg_list);

                id.nid = msg->msg_hdr.src_nid;
                id.pid = msg->msg_hdr.src_pid;

                LASSERT(!msg->msg_md);
                LASSERT(msg->msg_rx_delayed);
                LASSERT(msg->msg_rxpeer);
                LASSERT(msg->msg_hdr.type == LNET_MSG_PUT);

                CWARN("Dropping delayed PUT from %s portal %d match %llu offset %d length %d: %s\n",
                      libcfs_id2str(id),
                      msg->msg_hdr.msg.put.ptl_index,
                      msg->msg_hdr.msg.put.match_bits,
                      msg->msg_hdr.msg.put.offset,
                      msg->msg_hdr.payload_length, reason);

                /*
                 * NB I can't drop msg's ref on msg_rxpeer until after I've
                 * called lnet_drop_message(), so I just hang onto msg as well
                 * until that's done
                 */
                lnet_drop_message(msg->msg_rxpeer->lp_ni,
                                  msg->msg_rxpeer->lp_cpt,
                                  msg->msg_private, msg->msg_len);
                /*
                 * NB: message will not generate event because w/o attached MD,
                 * but we still should give error code so lnet_msg_decommit()
                 * can skip counters operations and other checks.
                 */
                lnet_finalize(msg->msg_rxpeer->lp_ni, msg, -ENOENT);
        }
}

void
lnet_recv_delayed_msg_list(struct list_head *head)
{
        while (!list_empty(head)) {
                lnet_msg_t *msg;
                lnet_process_id_t id;

                msg = list_entry(head->next, lnet_msg_t, msg_list);
                list_del(&msg->msg_list);

                /*
                 * md won't disappear under me, since each msg
                 * holds a ref on it
                 */
                id.nid = msg->msg_hdr.src_nid;
                id.pid = msg->msg_hdr.src_pid;

                LASSERT(msg->msg_rx_delayed);
                LASSERT(msg->msg_md);
                LASSERT(msg->msg_rxpeer);
                LASSERT(msg->msg_hdr.type == LNET_MSG_PUT);

                CDEBUG(D_NET, "Resuming delayed PUT from %s portal %d match %llu offset %d length %d.\n",
                       libcfs_id2str(id), msg->msg_hdr.msg.put.ptl_index,
                       msg->msg_hdr.msg.put.match_bits,
                       msg->msg_hdr.msg.put.offset,
                       msg->msg_hdr.payload_length);

                lnet_recv_put(msg->msg_rxpeer->lp_ni, msg);
        }
}

/**
 * Initiate an asynchronous PUT operation.
 *
 * There are several events associated with a PUT: completion of the send on
 * the initiator node (LNET_EVENT_SEND), and when the send completes
 * successfully, the receipt of an acknowledgment (LNET_EVENT_ACK) indicating
 * that the operation was accepted by the target. The event LNET_EVENT_PUT is
 * used at the target node to indicate the completion of incoming data
 * delivery.
 *
 * The local events will be logged in the EQ associated with the MD pointed to
 * by \a mdh handle. Using a MD without an associated EQ results in these
 * events being discarded. In this case, the caller must have another
 * mechanism (e.g., a higher level protocol) for determining when it is safe
 * to modify the memory region associated with the MD.
 *
 * Note that LNet does not guarantee the order of LNET_EVENT_SEND and
 * LNET_EVENT_ACK, though intuitively ACK should happen after SEND.
 *
 * \param self Indicates the NID of a local interface through which to send
 * the PUT request. Use LNET_NID_ANY to let LNet choose one by itself.
 * \param mdh A handle for the MD that describes the memory to be sent. The MD
 * must be "free floating" (See LNetMDBind()).
 * \param ack Controls whether an acknowledgment is requested.
 * Acknowledgments are only sent when they are requested by the initiating
 * process and the target MD enables them.
 * \param target A process identifier for the target process.
 * \param portal The index in the \a target's portal table.
 * \param match_bits The match bits to use for MD selection at the target
 * process.
 * \param offset The offset into the target MD (only used when the target
 * MD has the LNET_MD_MANAGE_REMOTE option set).
 * \param hdr_data 64 bits of user data that can be included in the message
 * header. This data is written to an event queue entry at the target if an
 * EQ is present on the matching MD.
 *
 * \retval  0      Success, and only in this case events will be generated
 * and logged to EQ (if it exists).
 * \retval -EIO    Simulated failure.
 * \retval -ENOMEM Memory allocation failure.
 * \retval -ENOENT Invalid MD object.
 *
 * \see lnet_event_t::hdr_data and lnet_event_kind_t.
 */
int
LNetPut(lnet_nid_t self, lnet_handle_md_t mdh, lnet_ack_req_t ack,
        lnet_process_id_t target, unsigned int portal,
        __u64 match_bits, unsigned int offset,
        __u64 hdr_data)
{
        struct lnet_msg *msg;
        struct lnet_libmd *md;
        int cpt;
        int rc;

        LASSERT(the_lnet.ln_refcount > 0);

        if (!list_empty(&the_lnet.ln_test_peers) && /* normally we don't */
            fail_peer(target.nid, 1)) { /* shall we now? */
                CERROR("Dropping PUT to %s: simulated failure\n",
                       libcfs_id2str(target));
                return -EIO;
        }

        msg = lnet_msg_alloc();
        if (!msg) {
                CERROR("Dropping PUT to %s: ENOMEM on lnet_msg_t\n",
                       libcfs_id2str(target));
                return -ENOMEM;
        }
        msg->msg_vmflush = !!memory_pressure_get();

        cpt = lnet_cpt_of_cookie(mdh.cookie);
        lnet_res_lock(cpt);

        md = lnet_handle2md(&mdh);
        if (!md || !md->md_threshold || md->md_me) {
                CERROR("Dropping PUT (%llu:%d:%s): MD (%d) invalid\n",
                       match_bits, portal, libcfs_id2str(target),
                       !md ? -1 : md->md_threshold);
                if (md && md->md_me)
                        CERROR("Source MD also attached to portal %d\n",
                               md->md_me->me_portal);
                lnet_res_unlock(cpt);

                lnet_msg_free(msg);
                return -ENOENT;
        }

        CDEBUG(D_NET, "LNetPut -> %s\n", libcfs_id2str(target));

        lnet_msg_attach_md(msg, md, 0, 0);

        lnet_prep_send(msg, LNET_MSG_PUT, target, 0, md->md_length);

        msg->msg_hdr.msg.put.match_bits = cpu_to_le64(match_bits);
        msg->msg_hdr.msg.put.ptl_index = cpu_to_le32(portal);
        msg->msg_hdr.msg.put.offset = cpu_to_le32(offset);
        msg->msg_hdr.msg.put.hdr_data = hdr_data;

        /* NB handles only looked up by creator (no flips) */
        if (ack == LNET_ACK_REQ) {
                msg->msg_hdr.msg.put.ack_wmd.wh_interface_cookie =
                        the_lnet.ln_interface_cookie;
                msg->msg_hdr.msg.put.ack_wmd.wh_object_cookie =
                        md->md_lh.lh_cookie;
        } else {
                msg->msg_hdr.msg.put.ack_wmd.wh_interface_cookie =
                        LNET_WIRE_HANDLE_COOKIE_NONE;
                msg->msg_hdr.msg.put.ack_wmd.wh_object_cookie =
                        LNET_WIRE_HANDLE_COOKIE_NONE;
        }

        lnet_res_unlock(cpt);

        lnet_build_msg_event(msg, LNET_EVENT_SEND);

        rc = lnet_send(self, msg, LNET_NID_ANY);
        if (rc) {
                CNETERR("Error sending PUT to %s: %d\n",
                        libcfs_id2str(target), rc);
                lnet_finalize(NULL, msg, rc);
        }

        /* completion will be signalled by an event */
        return 0;
}
EXPORT_SYMBOL(LNetPut);

lnet_msg_t *
lnet_create_reply_msg(lnet_ni_t *ni, lnet_msg_t *getmsg)
{
        /*
         * The LND can DMA direct to the GET md (i.e. no REPLY msg).  This
         * returns a msg for the LND to pass to lnet_finalize() when the sink
         * data has been received.
         *
         * CAVEAT EMPTOR: 'getmsg' is the original GET, which is freed when
         * lnet_finalize() is called on it, so the LND must call this first
         */
        struct lnet_msg *msg = lnet_msg_alloc();
        struct lnet_libmd *getmd = getmsg->msg_md;
        lnet_process_id_t peer_id = getmsg->msg_target;
        int cpt;

        LASSERT(!getmsg->msg_target_is_router);
        LASSERT(!getmsg->msg_routing);

        if (!msg) {
                CERROR("%s: Dropping REPLY from %s: can't allocate msg\n",
                       libcfs_nid2str(ni->ni_nid), libcfs_id2str(peer_id));
                goto drop;
        }

        cpt = lnet_cpt_of_cookie(getmd->md_lh.lh_cookie);
        lnet_res_lock(cpt);

        LASSERT(getmd->md_refcount > 0);

        if (!getmd->md_threshold) {
                CERROR("%s: Dropping REPLY from %s for inactive MD %p\n",
                       libcfs_nid2str(ni->ni_nid), libcfs_id2str(peer_id),
                       getmd);
                lnet_res_unlock(cpt);
                goto drop;
        }

        LASSERT(!getmd->md_offset);

        CDEBUG(D_NET, "%s: Reply from %s md %p\n",
               libcfs_nid2str(ni->ni_nid), libcfs_id2str(peer_id), getmd);

        /* setup information for lnet_build_msg_event */
        msg->msg_from = peer_id.nid;
        msg->msg_type = LNET_MSG_GET; /* flag this msg as an "optimized" GET */
        msg->msg_hdr.src_nid = peer_id.nid;
        msg->msg_hdr.payload_length = getmd->md_length;
        msg->msg_receiving = 1; /* required by lnet_msg_attach_md */

        lnet_msg_attach_md(msg, getmd, getmd->md_offset, getmd->md_length);
        lnet_res_unlock(cpt);

        cpt = lnet_cpt_of_nid(peer_id.nid);

        lnet_net_lock(cpt);
        lnet_msg_commit(msg, cpt);
        lnet_net_unlock(cpt);

        lnet_build_msg_event(msg, LNET_EVENT_REPLY);

        return msg;

 drop:
        cpt = lnet_cpt_of_nid(peer_id.nid);

        lnet_net_lock(cpt);
        the_lnet.ln_counters[cpt]->drop_count++;
        the_lnet.ln_counters[cpt]->drop_length += getmd->md_length;
        lnet_net_unlock(cpt);

        if (msg)
                lnet_msg_free(msg);

        return NULL;
}
EXPORT_SYMBOL(lnet_create_reply_msg);

void
lnet_set_reply_msg_len(lnet_ni_t *ni, lnet_msg_t *reply, unsigned int len)
{
        /*
         * Set the REPLY length, now the RDMA that elides the REPLY message has
         * completed and I know it.
         */
        LASSERT(reply);
        LASSERT(reply->msg_type == LNET_MSG_GET);
        LASSERT(reply->msg_ev.type == LNET_EVENT_REPLY);

        /*
         * NB I trusted my peer to RDMA.  If she tells me she's written beyond
         * the end of my buffer, I might as well be dead.
         */
        LASSERT(len <= reply->msg_ev.mlength);

        reply->msg_ev.mlength = len;
}
EXPORT_SYMBOL(lnet_set_reply_msg_len);

/**
 * Initiate an asynchronous GET operation.
 *
 * On the initiator node, an LNET_EVENT_SEND is logged when the GET request
 * is sent, and an LNET_EVENT_REPLY is logged when the data returned from
 * the target node in the REPLY has been written to local MD.
 *
 * On the target node, an LNET_EVENT_GET is logged when the GET request
 * arrives and is accepted into a MD.
 *
 * \param self,target,portal,match_bits,offset See the discussion in LNetPut().
 * \param mdh A handle for the MD that describes the memory into which the
 * requested data will be received. The MD must be "free floating"
 * (See LNetMDBind()).
 *
 * \retval  0      Success, and only in this case events will be generated
 * and logged to EQ (if it exists) of the MD.
 * \retval -EIO    Simulated failure.
 * \retval -ENOMEM Memory allocation failure.
 * \retval -ENOENT Invalid MD object.
 */
int
LNetGet(lnet_nid_t self, lnet_handle_md_t mdh,
        lnet_process_id_t target, unsigned int portal,
        __u64 match_bits, unsigned int offset)
{
        struct lnet_msg *msg;
        struct lnet_libmd *md;
        int cpt;
        int rc;

        LASSERT(the_lnet.ln_refcount > 0);

        if (!list_empty(&the_lnet.ln_test_peers) && /* normally we don't */
            fail_peer(target.nid, 1)) {   /* shall we now? */
                CERROR("Dropping GET to %s: simulated failure\n",
                       libcfs_id2str(target));
                return -EIO;
        }

        msg = lnet_msg_alloc();
        if (!msg) {
                CERROR("Dropping GET to %s: ENOMEM on lnet_msg_t\n",
                       libcfs_id2str(target));
                return -ENOMEM;
        }

        cpt = lnet_cpt_of_cookie(mdh.cookie);
        lnet_res_lock(cpt);

        md = lnet_handle2md(&mdh);
        if (!md || !md->md_threshold || md->md_me) {
                CERROR("Dropping GET (%llu:%d:%s): MD (%d) invalid\n",
                       match_bits, portal, libcfs_id2str(target),
                       !md ? -1 : md->md_threshold);
                if (md && md->md_me)
                        CERROR("REPLY MD also attached to portal %d\n",
                               md->md_me->me_portal);

                lnet_res_unlock(cpt);

                lnet_msg_free(msg);
                return -ENOENT;
        }

        CDEBUG(D_NET, "LNetGet -> %s\n", libcfs_id2str(target));

        lnet_msg_attach_md(msg, md, 0, 0);

        lnet_prep_send(msg, LNET_MSG_GET, target, 0, 0);

        msg->msg_hdr.msg.get.match_bits = cpu_to_le64(match_bits);
        msg->msg_hdr.msg.get.ptl_index = cpu_to_le32(portal);
        msg->msg_hdr.msg.get.src_offset = cpu_to_le32(offset);
        msg->msg_hdr.msg.get.sink_length = cpu_to_le32(md->md_length);

        /* NB handles only looked up by creator (no flips) */
        msg->msg_hdr.msg.get.return_wmd.wh_interface_cookie =
                the_lnet.ln_interface_cookie;
        msg->msg_hdr.msg.get.return_wmd.wh_object_cookie =
                md->md_lh.lh_cookie;

        lnet_res_unlock(cpt);

        lnet_build_msg_event(msg, LNET_EVENT_SEND);

        rc = lnet_send(self, msg, LNET_NID_ANY);
        if (rc < 0) {
                CNETERR("Error sending GET to %s: %d\n",
                        libcfs_id2str(target), rc);
                lnet_finalize(NULL, msg, rc);
        }

        /* completion will be signalled by an event */
        return 0;
}
EXPORT_SYMBOL(LNetGet);

/**
 * Calculate distance to node at \a dstnid.
 *
 * \param dstnid Target NID.
 * \param srcnidp If not NULL, NID of the local interface to reach \a dstnid
 * is saved here.
 * \param orderp If not NULL, order of the route to reach \a dstnid is saved
 * here.
 *
 * \retval 0 If \a dstnid belongs to a local interface, and reserved option
 * local_nid_dist_zero is set, which is the default.
 * \retval positives Distance to target NID, i.e. number of hops plus one.
 * \retval -EHOSTUNREACH If \a dstnid is not reachable.
 */
int
LNetDist(lnet_nid_t dstnid, lnet_nid_t *srcnidp, __u32 *orderp)
{
        struct list_head *e;
        struct lnet_ni *ni;
        lnet_remotenet_t *rnet;
        __u32 dstnet = LNET_NIDNET(dstnid);
        int hops;
        int cpt;
        __u32 order = 2;
        struct list_head *rn_list;

        /*
         * if !local_nid_dist_zero, I don't return a distance of 0 ever
         * (when lustre sees a distance of 0, it substitutes 0@lo), so I
         * keep order 0 free for 0@lo and order 1 free for a local NID
         * match
         */
        LASSERT(the_lnet.ln_refcount > 0);

        cpt = lnet_net_lock_current();

        list_for_each(e, &the_lnet.ln_nis) {
                ni = list_entry(e, lnet_ni_t, ni_list);

                if (ni->ni_nid == dstnid) {
                        if (srcnidp)
                                *srcnidp = dstnid;
                        if (orderp) {
                                if (LNET_NETTYP(LNET_NIDNET(dstnid)) == LOLND)
                                        *orderp = 0;
                                else
                                        *orderp = 1;
                        }
                        lnet_net_unlock(cpt);

                        return local_nid_dist_zero ? 0 : 1;
                }

                if (LNET_NIDNET(ni->ni_nid) == dstnet) {
                        /*
                         * Check if ni was originally created in
                         * current net namespace.
                         * If not, assign order above 0xffff0000,
                         * to make this ni not a priority.
                         */
                        if (!net_eq(ni->ni_net_ns, current->nsproxy->net_ns))
                                order += 0xffff0000;

                        if (srcnidp)
                                *srcnidp = ni->ni_nid;
                        if (orderp)
                                *orderp = order;
                        lnet_net_unlock(cpt);
                        return 1;
                }

                order++;
        }

        rn_list = lnet_net2rnethash(dstnet);
        list_for_each(e, rn_list) {
                rnet = list_entry(e, lnet_remotenet_t, lrn_list);

                if (rnet->lrn_net == dstnet) {
                        lnet_route_t *route;
                        lnet_route_t *shortest = NULL;
                        __u32 shortest_hops = LNET_UNDEFINED_HOPS;
                        __u32 route_hops;

                        LASSERT(!list_empty(&rnet->lrn_routes));

                        list_for_each_entry(route, &rnet->lrn_routes,
                                            lr_list) {
                                route_hops = route->lr_hops;
                                if (route_hops == LNET_UNDEFINED_HOPS)
                                        route_hops = 1;
                                if (!shortest ||
                                    route_hops < shortest_hops) {
                                        shortest = route;
                                        shortest_hops = route_hops;
                                }
                        }

                        LASSERT(shortest);
                        hops = shortest_hops;
                        if (srcnidp)
                                *srcnidp = shortest->lr_gateway->lp_ni->ni_nid;
                        if (orderp)
                                *orderp = order;
                        lnet_net_unlock(cpt);
                        return hops + 1;
                }
                order++;
        }

        lnet_net_unlock(cpt);
        return -EHOSTUNREACH;
}
EXPORT_SYMBOL(LNetDist);