[deliverable/linux.git] / drivers / staging / lustre / lnet / lnet / lib-move.c

/*
 * 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"

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) {
			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);