Whamcloud - gitweb
LU-9120 lnet: health error simulation
[fs/lustre-release.git] / lnet / lnet / lib-move.c
index 5a749b6..a89fa41 100644 (file)
@@ -23,7 +23,7 @@
  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
  *
- * Copyright (c) 2012, 2016, Intel Corporation.
+ * Copyright (c) 2012, 2017, Intel Corporation.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
@@ -36,6 +36,8 @@
 
 #define DEBUG_SUBSYSTEM S_LNET
 
+#include <linux/pagemap.h>
+
 #include <lnet/lib-lnet.h>
 #include <linux/nsproxy.h>
 #include <net/net_namespace.h>
@@ -44,10 +46,123 @@ static int local_nid_dist_zero = 1;
 module_param(local_nid_dist_zero, int, 0444);
 MODULE_PARM_DESC(local_nid_dist_zero, "Reserved");
 
+struct lnet_send_data {
+       struct lnet_ni *sd_best_ni;
+       struct lnet_peer_ni *sd_best_lpni;
+       struct lnet_peer_ni *sd_final_dst_lpni;
+       struct lnet_peer *sd_peer;
+       struct lnet_peer *sd_gw_peer;
+       struct lnet_peer_ni *sd_gw_lpni;
+       struct lnet_peer_net *sd_peer_net;
+       struct lnet_msg *sd_msg;
+       lnet_nid_t sd_dst_nid;
+       lnet_nid_t sd_src_nid;
+       lnet_nid_t sd_rtr_nid;
+       int sd_cpt;
+       int sd_md_cpt;
+       __u32 sd_send_case;
+};
+
+static inline struct lnet_comm_count *
+get_stats_counts(struct lnet_element_stats *stats,
+                enum lnet_stats_type stats_type)
+{
+       switch (stats_type) {
+       case LNET_STATS_TYPE_SEND:
+               return &stats->el_send_stats;
+       case LNET_STATS_TYPE_RECV:
+               return &stats->el_recv_stats;
+       case LNET_STATS_TYPE_DROP:
+               return &stats->el_drop_stats;
+       default:
+               CERROR("Unknown stats type\n");
+       }
+
+       return NULL;
+}
+
+void lnet_incr_stats(struct lnet_element_stats *stats,
+                    enum lnet_msg_type msg_type,
+                    enum lnet_stats_type stats_type)
+{
+       struct lnet_comm_count *counts = get_stats_counts(stats, stats_type);
+       if (!counts)
+               return;
+
+       switch (msg_type) {
+       case LNET_MSG_ACK:
+               atomic_inc(&counts->co_ack_count);
+               break;
+       case LNET_MSG_PUT:
+               atomic_inc(&counts->co_put_count);
+               break;
+       case LNET_MSG_GET:
+               atomic_inc(&counts->co_get_count);
+               break;
+       case LNET_MSG_REPLY:
+               atomic_inc(&counts->co_reply_count);
+               break;
+       case LNET_MSG_HELLO:
+               atomic_inc(&counts->co_hello_count);
+               break;
+       default:
+               CERROR("There is a BUG in the code. Unknown message type\n");
+               break;
+       }
+}
+
+__u32 lnet_sum_stats(struct lnet_element_stats *stats,
+                    enum lnet_stats_type stats_type)
+{
+       struct lnet_comm_count *counts = get_stats_counts(stats, stats_type);
+       if (!counts)
+               return 0;
+
+       return (atomic_read(&counts->co_ack_count) +
+               atomic_read(&counts->co_put_count) +
+               atomic_read(&counts->co_get_count) +
+               atomic_read(&counts->co_reply_count) +
+               atomic_read(&counts->co_hello_count));
+}
+
+static inline void assign_stats(struct lnet_ioctl_comm_count *msg_stats,
+                               struct lnet_comm_count *counts)
+{
+       msg_stats->ico_get_count = atomic_read(&counts->co_get_count);
+       msg_stats->ico_put_count = atomic_read(&counts->co_put_count);
+       msg_stats->ico_reply_count = atomic_read(&counts->co_reply_count);
+       msg_stats->ico_ack_count = atomic_read(&counts->co_ack_count);
+       msg_stats->ico_hello_count = atomic_read(&counts->co_hello_count);
+}
+
+void lnet_usr_translate_stats(struct lnet_ioctl_element_msg_stats *msg_stats,
+                             struct lnet_element_stats *stats)
+{
+       struct lnet_comm_count *counts;
+
+       LASSERT(msg_stats);
+       LASSERT(stats);
+
+       counts = get_stats_counts(stats, LNET_STATS_TYPE_SEND);
+       if (!counts)
+               return;
+       assign_stats(&msg_stats->im_send_stats, counts);
+
+       counts = get_stats_counts(stats, LNET_STATS_TYPE_RECV);
+       if (!counts)
+               return;
+       assign_stats(&msg_stats->im_recv_stats, counts);
+
+       counts = get_stats_counts(stats, LNET_STATS_TYPE_DROP);
+       if (!counts)
+               return;
+       assign_stats(&msg_stats->im_drop_stats, counts);
+}
+
 int
 lnet_fail_nid(lnet_nid_t nid, unsigned int threshold)
 {
-       lnet_test_peer_t *tp;
+       struct lnet_test_peer *tp;
        struct list_head *el;
        struct list_head *next;
        struct list_head  cull;
@@ -74,7 +189,7 @@ lnet_fail_nid(lnet_nid_t nid, unsigned int threshold)
        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);
+               tp = list_entry(el, struct lnet_test_peer, tp_list);
 
                if (tp->tp_threshold == 0 ||    /* needs culling anyway */
                    nid == LNET_NID_ANY ||      /* removing all entries */
@@ -87,7 +202,7 @@ lnet_fail_nid(lnet_nid_t nid, unsigned int threshold)
        lnet_net_unlock(0);
 
        while (!list_empty(&cull)) {
-               tp = list_entry(cull.next, lnet_test_peer_t, tp_list);
+               tp = list_entry(cull.next, struct lnet_test_peer, tp_list);
 
                list_del(&tp->tp_list);
                LIBCFS_FREE(tp, sizeof(*tp));
@@ -98,7 +213,7 @@ lnet_fail_nid(lnet_nid_t nid, unsigned int threshold)
 static int
 fail_peer (lnet_nid_t nid, int outgoing)
 {
-       lnet_test_peer_t *tp;
+       struct lnet_test_peer *tp;
        struct list_head *el;
        struct list_head *next;
        struct list_head  cull;
@@ -110,7 +225,7 @@ fail_peer (lnet_nid_t nid, int outgoing)
        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);
+               tp = list_entry(el, struct lnet_test_peer, tp_list);
 
                if (tp->tp_threshold == 0) {
                        /* zombie entry */
@@ -144,7 +259,7 @@ fail_peer (lnet_nid_t nid, int outgoing)
        lnet_net_unlock(0);
 
        while (!list_empty(&cull)) {
-               tp = list_entry(cull.next, lnet_test_peer_t, tp_list);
+               tp = list_entry(cull.next, struct lnet_test_peer, tp_list);
                list_del(&tp->tp_list);
 
                LIBCFS_FREE(tp, sizeof(*tp));
@@ -558,8 +673,9 @@ lnet_extract_kiov(int dst_niov, lnet_kiov_t *dst,
 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)
+lnet_ni_recv(struct lnet_ni *ni, void *private, struct lnet_msg *msg,
+            int delayed, unsigned int offset, unsigned int mlen,
+            unsigned int rlen)
 {
        unsigned int  niov = 0;
        struct kvec *iov = NULL;
@@ -584,21 +700,22 @@ lnet_ni_recv(lnet_ni_t *ni, void *private, lnet_msg_t *msg, int delayed,
                        iov  = msg->msg_iov;
                        kiov = msg->msg_kiov;
 
-                       LASSERT(niov > 0);
-                       LASSERT((iov == NULL) != (kiov == NULL));
+                       LASSERT (niov > 0);
+                       LASSERT ((iov == NULL) != (kiov == NULL));
                }
        }
 
-       rc = (ni->ni_lnd->lnd_recv)(ni, private, msg, delayed,
-                                   niov, iov, kiov, offset, mlen, rlen);
+       rc = (ni->ni_net->net_lnd->lnd_recv)(ni, private, msg, delayed,
+                                            niov, iov, kiov, offset, mlen,
+                                            rlen);
        if (rc < 0)
-               lnet_finalize(ni, msg, rc);
+               lnet_finalize(msg, rc);
 }
 
 static void
-lnet_setpayloadbuffer(lnet_msg_t *msg)
+lnet_setpayloadbuffer(struct lnet_msg *msg)
 {
-       lnet_libmd_t *md = msg->msg_md;
+       struct lnet_libmd *md = msg->msg_md;
 
        LASSERT(msg->msg_len > 0);
        LASSERT(!msg->msg_routing);
@@ -615,7 +732,7 @@ lnet_setpayloadbuffer(lnet_msg_t *msg)
 }
 
 void
-lnet_prep_send(lnet_msg_t *msg, int type, lnet_process_id_t target,
+lnet_prep_send(struct lnet_msg *msg, int type, struct lnet_process_id target,
               unsigned int offset, unsigned int len)
 {
        msg->msg_type = type;
@@ -626,47 +743,50 @@ lnet_prep_send(lnet_msg_t *msg, int type, lnet_process_id_t target,
        if (len != 0)
                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);
+       memset (&msg->msg_hdr, 0, sizeof (msg->msg_hdr));
+       msg->msg_hdr.type           = cpu_to_le32(type);
+       /* dest_nid will be overwritten by lnet_select_pathway() */
+       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.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)
+lnet_ni_send(struct lnet_ni *ni, struct lnet_msg *msg)
 {
        void   *priv = msg->msg_private;
-       int     rc;
+       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);
+       rc = (ni->ni_net->net_lnd->lnd_send)(ni, priv, msg);
+       if (rc < 0) {
+               msg->msg_no_resend = true;
+               lnet_finalize(msg, rc);
+       }
 }
 
 static int
-lnet_ni_eager_recv(lnet_ni_t *ni, lnet_msg_t *msg)
+lnet_ni_eager_recv(struct lnet_ni *ni, struct lnet_msg *msg)
 {
        int     rc;
 
        LASSERT(!msg->msg_sending);
        LASSERT(msg->msg_receiving);
        LASSERT(!msg->msg_rx_ready_delay);
-       LASSERT(ni->ni_lnd->lnd_eager_recv != NULL);
+       LASSERT(ni->ni_net->net_lnd->lnd_eager_recv != NULL);
 
        msg->msg_rx_ready_delay = 1;
-       rc = (ni->ni_lnd->lnd_eager_recv)(ni, msg->msg_private, msg,
-                                         &msg->msg_private);
+       rc = (ni->ni_net->net_lnd->lnd_eager_recv)(ni, msg->msg_private, msg,
+                                                 &msg->msg_private);
        if (rc != 0) {
                CERROR("recv from %s / send to %s aborted: "
                       "eager_recv failed %d\n",
-                      libcfs_nid2str(msg->msg_rxpeer->lp_nid),
+                      libcfs_nid2str(msg->msg_rxpeer->lpni_nid),
                       libcfs_id2str(msg->msg_target), rc);
                LASSERT(rc < 0); /* required by my callers */
        }
@@ -674,52 +794,69 @@ lnet_ni_eager_recv(lnet_ni_t *ni, lnet_msg_t *msg)
        return rc;
 }
 
-/* NB: caller shall hold a ref on 'lp' as I'd drop lnet_net_lock */
+/*
+ * This function can be called from two paths:
+ *     1. when sending a message
+ *     2. when decommiting a message (lnet_msg_decommit_tx())
+ * In both these cases the peer_ni should have it's reference count
+ * acquired by the caller and therefore it is safe to drop the spin
+ * lock before calling lnd_query()
+ */
 static void
-lnet_ni_query_locked(lnet_ni_t *ni, lnet_peer_t *lp)
+lnet_ni_query_locked(struct lnet_ni *ni, struct lnet_peer_ni *lp)
 {
-       cfs_time_t last_alive = 0;
+       time64_t last_alive = 0;
+       int cpt = lnet_cpt_of_nid_locked(lp->lpni_nid, ni);
 
        LASSERT(lnet_peer_aliveness_enabled(lp));
-       LASSERT(ni->ni_lnd->lnd_query != NULL);
+       LASSERT(ni->ni_net->net_lnd->lnd_query != NULL);
 
-       lnet_net_unlock(lp->lp_cpt);
-       (ni->ni_lnd->lnd_query)(ni, lp->lp_nid, &last_alive);
-       lnet_net_lock(lp->lp_cpt);
+       lnet_net_unlock(cpt);
+       (ni->ni_net->net_lnd->lnd_query)(ni, lp->lpni_nid, &last_alive);
+       lnet_net_lock(cpt);
 
-       lp->lp_last_query = cfs_time_current();
+       lp->lpni_last_query = ktime_get_seconds();
 
        if (last_alive != 0) /* NI has updated timestamp */
-               lp->lp_last_alive = last_alive;
+               lp->lpni_last_alive = last_alive;
 }
 
 /* NB: always called with lnet_net_lock held */
 static inline int
-lnet_peer_is_alive (lnet_peer_t *lp, cfs_time_t now)
+lnet_peer_is_alive(struct lnet_peer_ni *lp, time64_t now)
 {
-       int        alive;
-       cfs_time_t deadline;
+       int alive;
+       time64_t deadline;
 
-       LASSERT(lnet_peer_aliveness_enabled(lp));
+       LASSERT (lnet_peer_aliveness_enabled(lp));
 
-       /* Trust lnet_notify() if it has more recent aliveness news, but
+       /*
+        * 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))
+       spin_lock(&lp->lpni_lock);
+       if (!lp->lpni_alive && lp->lpni_alive_count > 0 &&
+           lp->lpni_timestamp >= lp->lpni_last_alive) {
+               spin_unlock(&lp->lpni_lock);
                return 0;
+       }
 
-       deadline = cfs_time_add(lp->lp_last_alive,
-                               cfs_time_seconds(lp->lp_ni->ni_peertimeout));
-       alive = cfs_time_after(deadline, now);
+       deadline = lp->lpni_last_alive +
+                  lp->lpni_net->net_tunables.lct_peer_timeout;
+       alive = deadline > now;
 
-       /* Update obsolete lp_alive except for routers assumed to be dead
+       /*
+        * 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.
+        * case, and moreover lpni_last_alive at peer creation is assumed.
         */
-       if (alive && !lp->lp_alive &&
-           !(lnet_isrouter(lp) && lp->lp_alive_count == 0))
-               lnet_notify_locked(lp, 0, 1, lp->lp_last_alive);
+       if (alive && !lp->lpni_alive &&
+           !(lnet_isrouter(lp) && lp->lpni_alive_count == 0)) {
+               spin_unlock(&lp->lpni_lock);
+               lnet_notify_locked(lp, 0, 1, lp->lpni_last_alive);
+       } else {
+               spin_unlock(&lp->lpni_lock);
+       }
 
        return alive;
 }
@@ -728,9 +865,9 @@ lnet_peer_is_alive (lnet_peer_t *lp, cfs_time_t now)
 /* 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)
+lnet_peer_alive_locked(struct lnet_ni *ni, struct lnet_peer_ni *lp)
 {
-       cfs_time_t now = cfs_time_current();
+       time64_t now = ktime_get_seconds();
 
        if (!lnet_peer_aliveness_enabled(lp))
                return -ENODEV;
@@ -738,34 +875,35 @@ lnet_peer_alive_locked (lnet_peer_t *lp)
        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 != 0) {
+       /*
+        * Peer appears dead, but we should avoid frequent NI queries (at
+        * most once per lnet_queryinterval seconds).
+        */
+       if (lp->lpni_last_query != 0) {
                static const int lnet_queryinterval = 1;
+               time64_t next_query;
 
-               cfs_time_t next_query =
-                          cfs_time_add(lp->lp_last_query,
-                                       cfs_time_seconds(lnet_queryinterval));
+               next_query = lp->lpni_last_query + lnet_queryinterval;
 
-               if (cfs_time_before(now, next_query)) {
-                       if (lp->lp_alive)
+               if (now < next_query) {
+                       if (lp->lpni_alive)
                                CWARN("Unexpected aliveness of peer %s: "
-                                     "%d < %d (%d/%d)\n",
-                                     libcfs_nid2str(lp->lp_nid),
-                                     (int)now, (int)next_query,
+                                     "%lld < %lld (%d/%d)\n",
+                                     libcfs_nid2str(lp->lpni_nid),
+                                     now, next_query,
                                      lnet_queryinterval,
-                                     lp->lp_ni->ni_peertimeout);
+                                     lp->lpni_net->net_tunables.lct_peer_timeout);
                        return 0;
                }
        }
 
        /* query NI for latest aliveness news */
-       lnet_ni_query_locked(lp->lp_ni, lp);
+       lnet_ni_query_locked(ni, lp);
 
        if (lnet_peer_is_alive(lp, now))
                return 1;
 
-       lnet_notify_locked(lp, 0, 0, lp->lp_last_alive);
+       lnet_notify_locked(lp, 0, 0, lp->lpni_last_alive);
        return 0;
 }
 
@@ -781,10 +919,10 @@ lnet_peer_alive_locked (lnet_peer_t *lp)
  * \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_post_send_locked(struct lnet_msg *msg, int do_send)
 {
-       lnet_peer_t             *lp = msg->msg_txpeer;
-       lnet_ni_t               *ni = lp->lp_ni;
+       struct lnet_peer_ni     *lp = msg->msg_txpeer;
+       struct lnet_ni          *ni = msg->msg_txni;
        int                     cpt = msg->msg_tx_cpt;
        struct lnet_tx_queue    *tq = ni->ni_tx_queues[cpt];
 
@@ -795,15 +933,25 @@ lnet_post_send_locked(lnet_msg_t *msg, int do_send)
 
        /* NB 'lp' is always the next hop */
        if ((msg->msg_target.pid & LNET_PID_USERFLAG) == 0 &&
-           lnet_peer_alive_locked(lp) == 0) {
+           lnet_peer_alive_locked(ni, lp) == 0) {
                the_lnet.ln_counters[cpt]->drop_count++;
                the_lnet.ln_counters[cpt]->drop_length += msg->msg_len;
                lnet_net_unlock(cpt);
+               if (msg->msg_txpeer)
+                       lnet_incr_stats(&msg->msg_txpeer->lpni_stats,
+                                       msg->msg_type,
+                                       LNET_STATS_TYPE_DROP);
+               if (msg->msg_txni)
+                       lnet_incr_stats(&msg->msg_txni->ni_stats,
+                                       msg->msg_type,
+                                       LNET_STATS_TYPE_DROP);
 
                CNETERR("Dropping message for %s: peer not alive\n",
                        libcfs_id2str(msg->msg_target));
-               if (do_send)
-                       lnet_finalize(ni, msg, -EHOSTUNREACH);
+               if (do_send) {
+                       msg->msg_health_status = LNET_MSG_STATUS_LOCAL_DROPPED;
+                       lnet_finalize(msg, -EHOSTUNREACH);
+               }
 
                lnet_net_lock(cpt);
                return -EHOSTUNREACH;
@@ -816,29 +964,34 @@ lnet_post_send_locked(lnet_msg_t *msg, int do_send)
                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);
+               if (do_send) {
+                       msg->msg_no_resend = true;
+                       lnet_finalize(msg, -ECANCELED);
+               }
 
                lnet_net_lock(cpt);
                return -ECANCELED;
        }
 
        if (!msg->msg_peertxcredit) {
-               LASSERT((lp->lp_txcredits < 0) ==
-                       !list_empty(&lp->lp_txq));
+               spin_lock(&lp->lpni_lock);
+               LASSERT((lp->lpni_txcredits < 0) ==
+                       !list_empty(&lp->lpni_txq));
 
                msg->msg_peertxcredit = 1;
-               lp->lp_txqnob += msg->msg_len + sizeof(lnet_hdr_t);
-               lp->lp_txcredits--;
+               lp->lpni_txqnob += msg->msg_len + sizeof(struct lnet_hdr);
+               lp->lpni_txcredits--;
 
-               if (lp->lp_txcredits < lp->lp_mintxcredits)
-                       lp->lp_mintxcredits = lp->lp_txcredits;
+               if (lp->lpni_txcredits < lp->lpni_mintxcredits)
+                       lp->lpni_mintxcredits = lp->lpni_txcredits;
 
-               if (lp->lp_txcredits < 0) {
+               if (lp->lpni_txcredits < 0) {
                        msg->msg_tx_delayed = 1;
-                       list_add_tail(&msg->msg_list, &lp->lp_txq);
+                       list_add_tail(&msg->msg_list, &lp->lpni_txq);
+                       spin_unlock(&lp->lpni_lock);
                        return LNET_CREDIT_WAIT;
                }
+               spin_unlock(&lp->lpni_lock);
        }
 
        if (!msg->msg_txcredit) {
@@ -847,6 +1000,7 @@ lnet_post_send_locked(lnet_msg_t *msg, int do_send)
 
                msg->msg_txcredit = 1;
                tq->tq_credits--;
+               atomic_dec(&ni->ni_tx_credits);
 
                if (tq->tq_credits < tq->tq_credits_min)
                        tq->tq_credits_min = tq->tq_credits;
@@ -858,6 +1012,9 @@ lnet_post_send_locked(lnet_msg_t *msg, int do_send)
                }
        }
 
+       /* unset the tx_delay flag as we're going to send it now */
+       msg->msg_tx_delayed = 0;
+
        if (do_send) {
                lnet_net_unlock(cpt);
                lnet_ni_send(ni, msg);
@@ -867,10 +1024,10 @@ lnet_post_send_locked(lnet_msg_t *msg, int do_send)
 }
 
 
-static lnet_rtrbufpool_t *
-lnet_msg2bufpool(lnet_msg_t *msg)
+static struct lnet_rtrbufpool *
+lnet_msg2bufpool(struct lnet_msg *msg)
 {
-       lnet_rtrbufpool_t       *rbp;
+       struct lnet_rtrbufpool  *rbp;
        int                     cpt;
 
        LASSERT(msg->msg_rx_committed);
@@ -888,42 +1045,45 @@ lnet_msg2bufpool(lnet_msg_t *msg)
 }
 
 static int
-lnet_post_routed_recv_locked (lnet_msg_t *msg, int do_recv)
+lnet_post_routed_recv_locked(struct lnet_msg *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;
+       struct lnet_peer_ni *lp = msg->msg_rxpeer;
+       struct lnet_rtrbufpool *rbp;
+       struct lnet_rtrbuf *rb;
 
-       LASSERT(msg->msg_iov == NULL);
-       LASSERT(msg->msg_kiov == NULL);
-       LASSERT(msg->msg_niov == 0);
-       LASSERT(msg->msg_routing);
-       LASSERT(msg->msg_receiving);
-       LASSERT(!msg->msg_sending);
+       LASSERT (msg->msg_iov == NULL);
+       LASSERT (msg->msg_kiov == NULL);
+       LASSERT (msg->msg_niov == 0);
+       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));
+               spin_lock(&lp->lpni_lock);
+               LASSERT((lp->lpni_rtrcredits < 0) ==
+                       !list_empty(&lp->lpni_rtrq));
 
                msg->msg_peerrtrcredit = 1;
-               lp->lp_rtrcredits--;
-               if (lp->lp_rtrcredits < lp->lp_minrtrcredits)
-                       lp->lp_minrtrcredits = lp->lp_rtrcredits;
+               lp->lpni_rtrcredits--;
+               if (lp->lpni_rtrcredits < lp->lpni_minrtrcredits)
+                       lp->lpni_minrtrcredits = lp->lpni_rtrcredits;
 
-               if (lp->lp_rtrcredits < 0) {
+               if (lp->lpni_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);
+                       list_add_tail(&msg->msg_list, &lp->lpni_rtrq);
+                       spin_unlock(&lp->lpni_lock);
                        return LNET_CREDIT_WAIT;
                }
+               spin_unlock(&lp->lpni_lock);
        }
 
        rbp = lnet_msg2bufpool(msg);
@@ -944,17 +1104,20 @@ lnet_post_routed_recv_locked (lnet_msg_t *msg, int do_recv)
        }
 
        LASSERT(!list_empty(&rbp->rbp_bufs));
-       rb = list_entry(rbp->rbp_bufs.next, lnet_rtrbuf_t, rb_list);
+       rb = list_entry(rbp->rbp_bufs.next, struct lnet_rtrbuf, rb_list);
        list_del(&rb->rb_list);
 
        msg->msg_niov = rbp->rbp_npages;
        msg->msg_kiov = &rb->rb_kiov[0];
 
+       /* unset the msg-rx_delayed flag since we're receiving the message */
+       msg->msg_rx_delayed = 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,
+               lnet_ni_recv(msg->msg_rxni, msg->msg_private, msg, 1,
                             0, msg->msg_len, msg->msg_len);
                lnet_net_lock(cpt);
        }
@@ -962,13 +1125,14 @@ lnet_post_routed_recv_locked (lnet_msg_t *msg, int do_recv)
 }
 
 void
-lnet_return_tx_credits_locked(lnet_msg_t *msg)
+lnet_return_tx_credits_locked(struct lnet_msg *msg)
 {
-       lnet_peer_t     *txpeer = msg->msg_txpeer;
-       lnet_msg_t      *msg2;
+       struct lnet_peer_ni     *txpeer = msg->msg_txpeer;
+       struct lnet_ni          *txni = msg->msg_txni;
+       struct lnet_msg         *msg2;
 
        if (msg->msg_txcredit) {
-               struct lnet_ni       *ni = txpeer->lp_ni;
+               struct lnet_ni       *ni = msg->msg_txni;
                struct lnet_tx_queue *tq = ni->ni_tx_queues[msg->msg_tx_cpt];
 
                /* give back NI txcredits */
@@ -978,13 +1142,15 @@ lnet_return_tx_credits_locked(lnet_msg_t *msg)
                        !list_empty(&tq->tq_delayed));
 
                tq->tq_credits++;
+               atomic_inc(&ni->ni_tx_credits);
                if (tq->tq_credits <= 0) {
                        msg2 = list_entry(tq->tq_delayed.next,
-                                         lnet_msg_t, msg_list);
+                                         struct lnet_msg, msg_list);
                        list_del(&msg2->msg_list);
 
-                       LASSERT(msg2->msg_txpeer->lp_ni == ni);
+                       LASSERT(msg2->msg_txni == ni);
                        LASSERT(msg2->msg_tx_delayed);
+                       LASSERT(msg2->msg_tx_cpt == msg->msg_tx_cpt);
 
                        (void) lnet_post_send_locked(msg2, 1);
                }
@@ -994,40 +1160,72 @@ lnet_return_tx_credits_locked(lnet_msg_t *msg)
                /* give back peer txcredits */
                msg->msg_peertxcredit = 0;
 
-               LASSERT((txpeer->lp_txcredits < 0) ==
-                       !list_empty(&txpeer->lp_txq));
+               spin_lock(&txpeer->lpni_lock);
+               LASSERT((txpeer->lpni_txcredits < 0) ==
+                       !list_empty(&txpeer->lpni_txq));
 
-               txpeer->lp_txqnob -= msg->msg_len + sizeof(lnet_hdr_t);
-               LASSERT(txpeer->lp_txqnob >= 0);
+               txpeer->lpni_txqnob -= msg->msg_len + sizeof(struct lnet_hdr);
+               LASSERT(txpeer->lpni_txqnob >= 0);
 
-               txpeer->lp_txcredits++;
-               if (txpeer->lp_txcredits <= 0) {
-                       msg2 = list_entry(txpeer->lp_txq.next,
-                                             lnet_msg_t, msg_list);
+               txpeer->lpni_txcredits++;
+               if (txpeer->lpni_txcredits <= 0) {
+                       int msg2_cpt;
+
+                       msg2 = list_entry(txpeer->lpni_txq.next,
+                                             struct lnet_msg, msg_list);
                        list_del(&msg2->msg_list);
+                       spin_unlock(&txpeer->lpni_lock);
 
                        LASSERT(msg2->msg_txpeer == txpeer);
                        LASSERT(msg2->msg_tx_delayed);
 
-                       (void) lnet_post_send_locked(msg2, 1);
+                       msg2_cpt = msg2->msg_tx_cpt;
+
+                       /*
+                        * The msg_cpt can be different from the msg2_cpt
+                        * so we need to make sure we lock the correct cpt
+                        * for msg2.
+                        * Once we call lnet_post_send_locked() it is no
+                        * longer safe to access msg2, since it could've
+                        * been freed by lnet_finalize(), but we still
+                        * need to relock the correct cpt, so we cache the
+                        * msg2_cpt for the purpose of the check that
+                        * follows the call to lnet_pose_send_locked().
+                        */
+                       if (msg2_cpt != msg->msg_tx_cpt) {
+                               lnet_net_unlock(msg->msg_tx_cpt);
+                               lnet_net_lock(msg2_cpt);
+                       }
+                        (void) lnet_post_send_locked(msg2, 1);
+                       if (msg2_cpt != msg->msg_tx_cpt) {
+                               lnet_net_unlock(msg2_cpt);
+                               lnet_net_lock(msg->msg_tx_cpt);
+                       }
+                } else {
+                       spin_unlock(&txpeer->lpni_lock);
                }
+        }
+
+       if (txni != NULL) {
+               msg->msg_txni = NULL;
+               lnet_ni_decref_locked(txni, msg->msg_tx_cpt);
        }
 
        if (txpeer != NULL) {
                msg->msg_txpeer = NULL;
-               lnet_peer_decref_locked(txpeer);
+               lnet_peer_ni_decref_locked(txpeer);
        }
 }
 
 void
-lnet_schedule_blocked_locked(lnet_rtrbufpool_t *rbp)
+lnet_schedule_blocked_locked(struct lnet_rtrbufpool *rbp)
 {
-       lnet_msg_t      *msg;
+       struct lnet_msg *msg;
 
        if (list_empty(&rbp->rbp_msgs))
                return;
        msg = list_entry(rbp->rbp_msgs.next,
-                        lnet_msg_t, msg_list);
+                        struct lnet_msg, msg_list);
        list_del(&msg->msg_list);
 
        (void)lnet_post_routed_recv_locked(msg, 1);
@@ -1036,43 +1234,40 @@ lnet_schedule_blocked_locked(lnet_rtrbufpool_t *rbp)
 void
 lnet_drop_routed_msgs_locked(struct list_head *list, int cpt)
 {
-       lnet_msg_t       *msg;
-       lnet_msg_t       *tmp;
-       struct list_head drop;
-
-       INIT_LIST_HEAD(&drop);
-
-       list_splice_init(list, &drop);
+       struct lnet_msg *msg;
+       struct lnet_msg *tmp;
 
        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,
+       list_for_each_entry_safe(msg, tmp, list, msg_list) {
+               lnet_ni_recv(msg->msg_rxni, msg->msg_private, NULL,
                             0, 0, 0, msg->msg_hdr.payload_length);
                list_del_init(&msg->msg_list);
-               lnet_finalize(NULL, msg, -ECANCELED);
+               msg->msg_no_resend = true;
+               lnet_finalize(msg, -ECANCELED);
        }
 
        lnet_net_lock(cpt);
 }
 
 void
-lnet_return_rx_credits_locked(lnet_msg_t *msg)
+lnet_return_rx_credits_locked(struct lnet_msg *msg)
 {
-       lnet_peer_t     *rxpeer = msg->msg_rxpeer;
-       lnet_msg_t      *msg2;
+       struct lnet_peer_ni *rxpeer = msg->msg_rxpeer;
+       struct lnet_ni *rxni = msg->msg_rxni;
+       struct lnet_msg *msg2;
 
        if (msg->msg_rtrcredit) {
                /* give back global router credits */
-               lnet_rtrbuf_t     *rb;
-               lnet_rtrbufpool_t *rbp;
+               struct lnet_rtrbuf *rb;
+               struct lnet_rtrbufpool *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 != NULL);
 
-               rb = list_entry(msg->msg_kiov, lnet_rtrbuf_t, rb_kiov[0]);
+               rb = list_entry(msg->msg_kiov, struct lnet_rtrbuf, rb_kiov[0]);
                rbp = rb->rb_pool;
 
                msg->msg_kiov = NULL;
@@ -1111,302 +1306,2291 @@ routing_off:
                /* give back peer router credits */
                msg->msg_peerrtrcredit = 0;
 
-               LASSERT((rxpeer->lp_rtrcredits < 0) ==
-                       !list_empty(&rxpeer->lp_rtrq));
+               spin_lock(&rxpeer->lpni_lock);
+               LASSERT((rxpeer->lpni_rtrcredits < 0) ==
+                       !list_empty(&rxpeer->lpni_rtrq));
 
-               rxpeer->lp_rtrcredits++;
+               rxpeer->lpni_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);
+                       struct list_head drop;
+                       INIT_LIST_HEAD(&drop);
+                       list_splice_init(&rxpeer->lpni_rtrq, &drop);
+                       spin_unlock(&rxpeer->lpni_lock);
+                       lnet_drop_routed_msgs_locked(&drop, msg->msg_rx_cpt);
+               } else if (rxpeer->lpni_rtrcredits <= 0) {
+                       msg2 = list_entry(rxpeer->lpni_rtrq.next,
+                                         struct lnet_msg, msg_list);
                        list_del(&msg2->msg_list);
-
+                       spin_unlock(&rxpeer->lpni_lock);
                        (void) lnet_post_routed_recv_locked(msg2, 1);
+               } else {
+                       spin_unlock(&rxpeer->lpni_lock);
                }
        }
+       if (rxni != NULL) {
+               msg->msg_rxni = NULL;
+               lnet_ni_decref_locked(rxni, msg->msg_rx_cpt);
+       }
        if (rxpeer != NULL) {
                msg->msg_rxpeer = NULL;
-               lnet_peer_decref_locked(rxpeer);
+               lnet_peer_ni_decref_locked(rxpeer);
+       }
+}
+
+static int
+lnet_compare_peers(struct lnet_peer_ni *p1, struct lnet_peer_ni *p2)
+{
+       if (p1->lpni_txqnob < p2->lpni_txqnob)
+               return 1;
+
+       if (p1->lpni_txqnob > p2->lpni_txqnob)
+               return -1;
+
+       if (p1->lpni_txcredits > p2->lpni_txcredits)
+               return 1;
+
+       if (p1->lpni_txcredits < p2->lpni_txcredits)
+               return -1;
+
+       return 0;
+}
+
+static int
+lnet_compare_routes(struct lnet_route *r1, struct lnet_route *r2)
+{
+       struct lnet_peer_ni *p1 = r1->lr_gateway;
+       struct lnet_peer_ni *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;
+       int rc;
+
+       if (r1->lr_priority < r2->lr_priority)
+               return 1;
+
+       if (r1->lr_priority > r2->lr_priority)
+               return -1;
+
+       if (r1_hops < r2_hops)
+               return 1;
+
+       if (r1_hops > r2_hops)
+               return -1;
+
+       rc = lnet_compare_peers(p1, p2);
+       if (rc)
+               return rc;
+
+       if (r1->lr_seq - r2->lr_seq <= 0)
+               return 1;
+
+       return -1;
+}
+
+static struct lnet_peer_ni *
+lnet_find_route_locked(struct lnet_net *net, __u32 remote_net,
+                      lnet_nid_t rtr_nid)
+{
+       struct lnet_remotenet   *rnet;
+       struct lnet_route               *route;
+       struct lnet_route               *best_route;
+       struct lnet_route               *last_route;
+       struct lnet_peer_ni     *lpni_best;
+       struct lnet_peer_ni     *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_rnet_locked(remote_net);
+       if (rnet == NULL)
+               return NULL;
+
+       lpni_best = NULL;
+       best_route = 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 (net != NULL && lp->lpni_net != net)
+                       continue;
+
+               if (lp->lpni_nid == rtr_nid) /* it's pre-determined router */
+                       return lp;
+
+               if (lpni_best == NULL) {
+                       best_route = last_route = route;
+                       lpni_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;
+               lpni_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 != NULL)
+               best_route->lr_seq = last_route->lr_seq + 1;
+       return lpni_best;
+}
+
+static struct lnet_ni *
+lnet_get_best_ni(struct lnet_net *local_net, struct lnet_ni *best_ni,
+                struct lnet_peer *peer, struct lnet_peer_net *peer_net,
+                int md_cpt)
+{
+       struct lnet_ni *ni = NULL;
+       unsigned int shortest_distance;
+       int best_credits;
+       int best_healthv;
+
+       /*
+        * If there is no peer_ni that we can send to on this network,
+        * then there is no point in looking for a new best_ni here.
+       */
+       if (!lnet_get_next_peer_ni_locked(peer, peer_net, NULL))
+               return best_ni;
+
+       if (best_ni == NULL) {
+               shortest_distance = UINT_MAX;
+               best_credits = INT_MIN;
+               best_healthv = 0;
+       } else {
+               shortest_distance = cfs_cpt_distance(lnet_cpt_table(), md_cpt,
+                                                    best_ni->ni_dev_cpt);
+               best_credits = atomic_read(&best_ni->ni_tx_credits);
+               best_healthv = atomic_read(&best_ni->ni_healthv);
+       }
+
+       while ((ni = lnet_get_next_ni_locked(local_net, ni))) {
+               unsigned int distance;
+               int ni_credits;
+               int ni_healthv;
+               int ni_fatal;
+
+               ni_credits = atomic_read(&ni->ni_tx_credits);
+               ni_healthv = atomic_read(&ni->ni_healthv);
+               ni_fatal = atomic_read(&ni->ni_fatal_error_on);
+
+               /*
+                * calculate the distance from the CPT on which
+                * the message memory is allocated to the CPT of
+                * the NI's physical device
+                */
+               distance = cfs_cpt_distance(lnet_cpt_table(),
+                                           md_cpt,
+                                           ni->ni_dev_cpt);
+
+               CDEBUG(D_NET, "compare ni %s [c:%d, d:%d, s:%d] with best_ni %s [c:%d, d:%d, s:%d]\n",
+                      libcfs_nid2str(ni->ni_nid), ni_credits, distance,
+                      ni->ni_seq, (best_ni) ? libcfs_nid2str(best_ni->ni_nid)
+                       : "not seleced", best_credits, shortest_distance,
+                       (best_ni) ? best_ni->ni_seq : 0);
+
+               /*
+                * All distances smaller than the NUMA range
+                * are treated equally.
+                */
+               if (distance < lnet_numa_range)
+                       distance = lnet_numa_range;
+
+               /*
+                * Select on health, shorter distance, available
+                * credits, then round-robin.
+                */
+               if (ni_fatal) {
+                       continue;
+               } else if (ni_healthv < best_healthv) {
+                       continue;
+               } else if (ni_healthv > best_healthv) {
+                       best_healthv = ni_healthv;
+                       /*
+                        * If we're going to prefer this ni because it's
+                        * the healthiest, then we should set the
+                        * shortest_distance in the algorithm in case
+                        * there are multiple NIs with the same health but
+                        * different distances.
+                        */
+                       if (distance < shortest_distance)
+                               shortest_distance = distance;
+               } else if (distance > shortest_distance) {
+                       continue;
+               } else if (distance < shortest_distance) {
+                       shortest_distance = distance;
+               } else if (ni_credits < best_credits) {
+                       continue;
+               } else if (ni_credits == best_credits) {
+                       if (best_ni && best_ni->ni_seq <= ni->ni_seq)
+                               continue;
+               }
+               best_ni = ni;
+               best_credits = ni_credits;
+       }
+
+       CDEBUG(D_NET, "selected best_ni %s\n",
+              (best_ni) ? libcfs_nid2str(best_ni->ni_nid) : "no selection");
+
+       return best_ni;
+}
+
+/*
+ * Traffic to the LNET_RESERVED_PORTAL may not trigger peer discovery,
+ * because such traffic is required to perform discovery. We therefore
+ * exclude all GET and PUT on that portal. We also exclude all ACK and
+ * REPLY traffic, but that is because the portal is not tracked in the
+ * message structure for these message types. We could restrict this
+ * further by also checking for LNET_PROTO_PING_MATCHBITS.
+ */
+static bool
+lnet_msg_discovery(struct lnet_msg *msg)
+{
+       if (msg->msg_type == LNET_MSG_PUT) {
+               if (msg->msg_hdr.msg.put.ptl_index != LNET_RESERVED_PORTAL)
+                       return true;
+       } else if (msg->msg_type == LNET_MSG_GET) {
+               if (msg->msg_hdr.msg.get.ptl_index != LNET_RESERVED_PORTAL)
+                       return true;
+       }
+       return false;
+}
+
+#define SRC_SPEC       0x0001
+#define SRC_ANY                0x0002
+#define LOCAL_DST      0x0004
+#define REMOTE_DST     0x0008
+#define MR_DST         0x0010
+#define NMR_DST                0x0020
+#define SND_RESP       0x0040
+
+/* The following to defines are used for return codes */
+#define REPEAT_SEND    0x1000
+#define PASS_THROUGH   0x2000
+
+/* The different cases lnet_select pathway needs to handle */
+#define SRC_SPEC_LOCAL_MR_DST  (SRC_SPEC | LOCAL_DST | MR_DST)
+#define SRC_SPEC_ROUTER_MR_DST (SRC_SPEC | REMOTE_DST | MR_DST)
+#define SRC_SPEC_LOCAL_NMR_DST (SRC_SPEC | LOCAL_DST | NMR_DST)
+#define SRC_SPEC_ROUTER_NMR_DST        (SRC_SPEC | REMOTE_DST | NMR_DST)
+#define SRC_ANY_LOCAL_MR_DST   (SRC_ANY | LOCAL_DST | MR_DST)
+#define SRC_ANY_ROUTER_MR_DST  (SRC_ANY | REMOTE_DST | MR_DST)
+#define SRC_ANY_LOCAL_NMR_DST  (SRC_ANY | LOCAL_DST | NMR_DST)
+#define SRC_ANY_ROUTER_NMR_DST (SRC_ANY | REMOTE_DST | NMR_DST)
+
+static int
+lnet_handle_send(struct lnet_send_data *sd)
+{
+       struct lnet_ni *best_ni = sd->sd_best_ni;
+       struct lnet_peer_ni *best_lpni = sd->sd_best_lpni;
+       struct lnet_peer_ni *final_dst_lpni = sd->sd_final_dst_lpni;
+       struct lnet_msg *msg = sd->sd_msg;
+       int cpt2;
+       __u32 send_case = sd->sd_send_case;
+       int rc;
+       __u32 routing = send_case & REMOTE_DST;
+
+       /*
+        * Increment sequence number of the selected peer so that we
+        * pick the next one in Round Robin.
+        */
+       best_lpni->lpni_seq++;
+
+       /*
+        * grab a reference on the peer_ni so it sticks around even if
+        * we need to drop and relock the lnet_net_lock below.
+        */
+       lnet_peer_ni_addref_locked(best_lpni);
+
+       /*
+        * Use lnet_cpt_of_nid() to determine the CPT used to commit the
+        * message. This ensures that we get a CPT that is correct for
+        * the NI when the NI has been restricted to a subset of all CPTs.
+        * If the selected CPT differs from the one currently locked, we
+        * must unlock and relock the lnet_net_lock(), and then check whether
+        * the configuration has changed. We don't have a hold on the best_ni
+        * yet, and it may have vanished.
+        */
+       cpt2 = lnet_cpt_of_nid_locked(best_lpni->lpni_nid, best_ni);
+       if (sd->sd_cpt != cpt2) {
+               __u32 seq = lnet_get_dlc_seq_locked();
+               lnet_net_unlock(sd->sd_cpt);
+               sd->sd_cpt = cpt2;
+               lnet_net_lock(sd->sd_cpt);
+               if (seq != lnet_get_dlc_seq_locked()) {
+                       lnet_peer_ni_decref_locked(best_lpni);
+                       return REPEAT_SEND;
+               }
+       }
+
+       /*
+        * store the best_lpni in the message right away to avoid having
+        * to do the same operation under different conditions
+        */
+       msg->msg_txpeer = best_lpni;
+       msg->msg_txni = best_ni;
+
+       /*
+        * grab a reference for the best_ni since now it's in use in this
+        * send. The reference will be dropped in lnet_finalize()
+        */
+       lnet_ni_addref_locked(msg->msg_txni, sd->sd_cpt);
+
+       /*
+        * Always set the target.nid to the best peer picked. Either the
+        * NID will be one of the peer NIDs selected, or the same NID as
+        * what was originally set in the target or it will be the NID of
+        * a router if this message should be routed
+        */
+       msg->msg_target.nid = msg->msg_txpeer->lpni_nid;
+
+       /*
+        * lnet_msg_commit assigns the correct cpt to the message, which
+        * is used to decrement the correct refcount on the ni when it's
+        * time to return the credits
+        */
+       lnet_msg_commit(msg, sd->sd_cpt);
+
+       /*
+        * If we are routing the message then we keep the src_nid that was
+        * set by the originator. If we are not routing then we are the
+        * originator and set it here.
+        */
+       if (!msg->msg_routing)
+               msg->msg_hdr.src_nid = cpu_to_le64(msg->msg_txni->ni_nid);
+
+       if (routing) {
+               msg->msg_target_is_router = 1;
+               msg->msg_target.pid = LNET_PID_LUSTRE;
+               /*
+                * since we're routing we want to ensure that the
+                * msg_hdr.dest_nid is set to the final destination. When
+                * the router receives this message it knows how to route
+                * it.
+                *
+                * final_dst_lpni is set at the beginning of the
+                * lnet_select_pathway() function and is never changed.
+                * It's safe to use it here.
+                */
+               msg->msg_hdr.dest_nid = cpu_to_le64(final_dst_lpni->lpni_nid);
+       } else {
+               /*
+                * if we're not routing set the dest_nid to the best peer
+                * ni NID that we picked earlier in the algorithm.
+                */
+               msg->msg_hdr.dest_nid = cpu_to_le64(msg->msg_txpeer->lpni_nid);
+       }
+
+       rc = lnet_post_send_locked(msg, 0);
+
+       if (!rc)
+               CDEBUG(D_NET, "TRACE: %s(%s:%s) -> %s(%s:%s) : %s\n",
+                      libcfs_nid2str(msg->msg_hdr.src_nid),
+                      libcfs_nid2str(msg->msg_txni->ni_nid),
+                      libcfs_nid2str(sd->sd_src_nid),
+                      libcfs_nid2str(msg->msg_hdr.dest_nid),
+                      libcfs_nid2str(sd->sd_dst_nid),
+                      libcfs_nid2str(msg->msg_txpeer->lpni_nid),
+                      lnet_msgtyp2str(msg->msg_type));
+
+       return rc;
+}
+
+static struct lnet_peer_ni *
+lnet_select_peer_ni(struct lnet_send_data *sd, struct lnet_peer *peer,
+                   struct lnet_peer_net *peer_net)
+{
+       /*
+        * Look at the peer NIs for the destination peer that connect
+        * to the chosen net. If a peer_ni is preferred when using the
+        * best_ni to communicate, we use that one. If there is no
+        * preferred peer_ni, or there are multiple preferred peer_ni,
+        * the available transmit credits are used. If the transmit
+        * credits are equal, we round-robin over the peer_ni.
+        */
+       struct lnet_peer_ni *lpni = NULL;
+       struct lnet_peer_ni *best_lpni = NULL;
+       struct lnet_ni *best_ni = sd->sd_best_ni;
+       lnet_nid_t dst_nid = sd->sd_dst_nid;
+       int best_lpni_credits = INT_MIN;
+       bool preferred = false;
+       bool ni_is_pref;
+       int best_lpni_healthv = 0;
+       int lpni_healthv;
+
+       while ((lpni = lnet_get_next_peer_ni_locked(peer, peer_net, lpni))) {
+               /*
+                * if the best_ni we've chosen aleady has this lpni
+                * preferred, then let's use it
+                */
+               ni_is_pref = lnet_peer_is_pref_nid_locked(lpni,
+                                                         best_ni->ni_nid);
+
+               lpni_healthv = atomic_read(&lpni->lpni_healthv);
+
+               CDEBUG(D_NET, "%s ni_is_pref = %d\n",
+                      libcfs_nid2str(best_ni->ni_nid), ni_is_pref);
+
+               if (best_lpni)
+                       CDEBUG(D_NET, "%s c:[%d, %d], s:[%d, %d]\n",
+                               libcfs_nid2str(lpni->lpni_nid),
+                               lpni->lpni_txcredits, best_lpni_credits,
+                               lpni->lpni_seq, best_lpni->lpni_seq);
+
+               /* pick the healthiest peer ni */
+               if (lpni_healthv < best_lpni_healthv) {
+                       continue;
+               } else if (lpni_healthv > best_lpni_healthv) {
+                       best_lpni_healthv = lpni_healthv;
+               /* if this is a preferred peer use it */
+               } else if (!preferred && ni_is_pref) {
+                       preferred = true;
+               } else if (preferred && !ni_is_pref) {
+                       /*
+                        * this is not the preferred peer so let's ignore
+                        * it.
+                        */
+                       continue;
+               } else if (lpni->lpni_txcredits < best_lpni_credits) {
+                       /*
+                        * We already have a peer that has more credits
+                        * available than this one. No need to consider
+                        * this peer further.
+                        */
+                       continue;
+               } else if (lpni->lpni_txcredits == best_lpni_credits) {
+                       /*
+                        * The best peer found so far and the current peer
+                        * have the same number of available credits let's
+                        * make sure to select between them using Round
+                        * Robin
+                        */
+                       if (best_lpni) {
+                               if (best_lpni->lpni_seq <= lpni->lpni_seq)
+                                       continue;
+                       }
+               }
+
+               best_lpni = lpni;
+               best_lpni_credits = lpni->lpni_txcredits;
+       }
+
+       /* if we still can't find a peer ni then we can't reach it */
+       if (!best_lpni) {
+               __u32 net_id = (peer_net) ? peer_net->lpn_net_id :
+                       LNET_NIDNET(dst_nid);
+               CDEBUG(D_NET, "no peer_ni found on peer net %s\n",
+                               libcfs_net2str(net_id));
+               return NULL;
+       }
+
+       CDEBUG(D_NET, "sd_best_lpni = %s\n",
+              libcfs_nid2str(best_lpni->lpni_nid));
+
+       return best_lpni;
+}
+
+/*
+ * Prerequisite: the best_ni should already be set in the sd
+ */
+static inline struct lnet_peer_ni *
+lnet_find_best_lpni_on_net(struct lnet_send_data *sd, struct lnet_peer *peer,
+                          __u32 net_id)
+{
+       struct lnet_peer_net *peer_net;
+
+       /*
+        * The gateway is Multi-Rail capable so now we must select the
+        * proper peer_ni
+        */
+       peer_net = lnet_peer_get_net_locked(peer, net_id);
+
+       if (!peer_net) {
+               CERROR("gateway peer %s has no NI on net %s\n",
+                      libcfs_nid2str(peer->lp_primary_nid),
+                      libcfs_net2str(net_id));
+               return NULL;
+       }
+
+       return lnet_select_peer_ni(sd, peer, peer_net);
+}
+
+static inline void
+lnet_set_non_mr_pref_nid(struct lnet_send_data *sd)
+{
+       if (sd->sd_send_case & NMR_DST &&
+           sd->sd_msg->msg_type != LNET_MSG_REPLY &&
+           sd->sd_msg->msg_type != LNET_MSG_ACK &&
+           sd->sd_best_lpni->lpni_pref_nnids == 0) {
+               CDEBUG(D_NET, "Setting preferred local NID %s on NMR peer %s\n",
+                      libcfs_nid2str(sd->sd_best_ni->ni_nid),
+                      libcfs_nid2str(sd->sd_best_lpni->lpni_nid));
+               lnet_peer_ni_set_non_mr_pref_nid(sd->sd_best_lpni,
+                                                sd->sd_best_ni->ni_nid);
+       }
+}
+
+/*
+ * Source Specified
+ * Local Destination
+ * non-mr peer
+ *
+ * use the source and destination NIDs as the pathway
+ */
+static int
+lnet_handle_spec_local_nmr_dst(struct lnet_send_data *sd)
+{
+       /* the destination lpni is set before we get here. */
+
+       /* find local NI */
+       sd->sd_best_ni = lnet_nid2ni_locked(sd->sd_src_nid, sd->sd_cpt);
+       if (!sd->sd_best_ni) {
+               CERROR("Can't send to %s: src %s is not a "
+                      "local nid\n", libcfs_nid2str(sd->sd_dst_nid),
+                               libcfs_nid2str(sd->sd_src_nid));
+               return -EINVAL;
+       }
+
+       /*
+        * the preferred NID will only be set for NMR peers
+        */
+       lnet_set_non_mr_pref_nid(sd);
+
+       return lnet_handle_send(sd);
+}
+
+/*
+ * Source Specified
+ * Local Destination
+ * MR Peer
+ *
+ * Run the selection algorithm on the peer NIs unless we're sending
+ * a response, in this case just send to the destination
+ */
+static int
+lnet_handle_spec_local_mr_dst(struct lnet_send_data *sd)
+{
+       sd->sd_best_ni = lnet_nid2ni_locked(sd->sd_src_nid, sd->sd_cpt);
+       if (!sd->sd_best_ni) {
+               CERROR("Can't send to %s: src %s is not a "
+                      "local nid\n", libcfs_nid2str(sd->sd_dst_nid),
+                               libcfs_nid2str(sd->sd_src_nid));
+               return -EINVAL;
+       }
+
+       /*
+        * only run the selection algorithm to pick the peer_ni if we're
+        * sending a GET or a PUT. Responses are sent to the same
+        * destination NID provided.
+        */
+       if (!(sd->sd_send_case & SND_RESP)) {
+               sd->sd_best_lpni =
+                 lnet_find_best_lpni_on_net(sd, sd->sd_peer,
+                                            sd->sd_best_ni->ni_net->net_id);
+       }
+
+       if (sd->sd_best_lpni)
+               return lnet_handle_send(sd);
+
+       CERROR("can't send to %s. no NI on %s\n",
+              libcfs_nid2str(sd->sd_dst_nid),
+              libcfs_net2str(sd->sd_best_ni->ni_net->net_id));
+
+       return -EHOSTUNREACH;
+}
+
+struct lnet_ni *
+lnet_find_best_ni_on_spec_net(struct lnet_ni *cur_best_ni,
+                             struct lnet_peer *peer,
+                             struct lnet_peer_net *peer_net,
+                             int cpt,
+                             bool incr_seq)
+{
+       struct lnet_net *local_net;
+       struct lnet_ni *best_ni;
+
+       local_net = lnet_get_net_locked(peer_net->lpn_net_id);
+       if (!local_net)
+               return NULL;
+
+       /*
+        * Iterate through the NIs in this local Net and select
+        * the NI to send from. The selection is determined by
+        * these 3 criterion in the following priority:
+        *      1. NUMA
+        *      2. NI available credits
+        *      3. Round Robin
+        */
+       best_ni = lnet_get_best_ni(local_net, cur_best_ni,
+                                  peer, peer_net, cpt);
+
+       if (incr_seq && best_ni)
+               best_ni->ni_seq++;
+
+       return best_ni;
+}
+
+static int
+lnet_handle_find_routed_path(struct lnet_send_data *sd,
+                            lnet_nid_t dst_nid,
+                            struct lnet_peer_ni **gw_lpni,
+                            struct lnet_peer **gw_peer)
+{
+       struct lnet_peer_ni *gw;
+       lnet_nid_t src_nid = sd->sd_src_nid;
+
+       gw = lnet_find_route_locked(NULL, LNET_NIDNET(dst_nid),
+                                   sd->sd_rtr_nid);
+       if (!gw) {
+               CERROR("no route to %s from %s\n",
+                      libcfs_nid2str(dst_nid), libcfs_nid2str(src_nid));
+               return -EHOSTUNREACH;
+       }
+
+       /* get the peer of the gw_ni */
+       LASSERT(gw->lpni_peer_net);
+       LASSERT(gw->lpni_peer_net->lpn_peer);
+
+       *gw_peer = gw->lpni_peer_net->lpn_peer;
+
+       if (!sd->sd_best_ni)
+               sd->sd_best_ni = lnet_find_best_ni_on_spec_net(NULL, *gw_peer,
+                                       gw->lpni_peer_net,
+                                       sd->sd_md_cpt,
+                                       true);
+
+       if (!sd->sd_best_ni) {
+               CERROR("Internal Error. Expected local ni on %s "
+                      "but non found :%s\n",
+                      libcfs_net2str(gw->lpni_peer_net->lpn_net_id),
+                      libcfs_nid2str(sd->sd_src_nid));
+               return -EFAULT;
+       }
+
+       /*
+        * if gw is MR let's find its best peer_ni
+        */
+       if (lnet_peer_is_multi_rail(*gw_peer)) {
+               gw = lnet_find_best_lpni_on_net(sd, *gw_peer,
+                                               sd->sd_best_ni->ni_net->net_id);
+               /*
+                * We've already verified that the gw has an NI on that
+                * desired net, but we're not finding it. Something is
+                * wrong.
+                */
+               if (!gw) {
+                       CERROR("Internal Error. Route expected to %s from %s\n",
+                               libcfs_nid2str(dst_nid),
+                               libcfs_nid2str(src_nid));
+                       return -EFAULT;
+               }
+       }
+
+       *gw_lpni = gw;
+
+       return 0;
+}
+
+/*
+ * Handle two cases:
+ *
+ * Case 1:
+ *  Source specified
+ *  Remote destination
+ *  Non-MR destination
+ *
+ * Case 2:
+ *  Source specified
+ *  Remote destination
+ *  MR destination
+ *
+ * The handling of these two cases is similar. Even though the destination
+ * can be MR or non-MR, we'll deal directly with the router.
+ */
+static int
+lnet_handle_spec_router_dst(struct lnet_send_data *sd)
+{
+       int rc;
+       struct lnet_peer_ni *gw_lpni = NULL;
+       struct lnet_peer *gw_peer = NULL;
+
+       /* find local NI */
+       sd->sd_best_ni = lnet_nid2ni_locked(sd->sd_src_nid, sd->sd_cpt);
+       if (!sd->sd_best_ni) {
+               CERROR("Can't send to %s: src %s is not a "
+                      "local nid\n", libcfs_nid2str(sd->sd_dst_nid),
+                               libcfs_nid2str(sd->sd_src_nid));
+               return -EINVAL;
+       }
+
+       rc = lnet_handle_find_routed_path(sd, sd->sd_dst_nid, &gw_lpni,
+                                    &gw_peer);
+       if (rc < 0)
+               return rc;
+
+       if (sd->sd_send_case & NMR_DST)
+               /*
+               * since the final destination is non-MR let's set its preferred
+               * NID before we send
+               */
+               lnet_set_non_mr_pref_nid(sd);
+
+       /*
+        * We're going to send to the gw found so let's set its
+        * info
+        */
+       sd->sd_peer = gw_peer;
+       sd->sd_best_lpni = gw_lpni;
+
+       return lnet_handle_send(sd);
+}
+
+struct lnet_ni *
+lnet_find_best_ni_on_local_net(struct lnet_peer *peer, int md_cpt)
+{
+       struct lnet_peer_net *peer_net = NULL;
+       struct lnet_ni *best_ni = NULL;
+
+       /*
+        * The peer can have multiple interfaces, some of them can be on
+        * the local network and others on a routed network. We should
+        * prefer the local network. However if the local network is not
+        * available then we need to try the routed network
+        */
+
+       /* go through all the peer nets and find the best_ni */
+       list_for_each_entry(peer_net, &peer->lp_peer_nets, lpn_peer_nets) {
+               /*
+                * The peer's list of nets can contain non-local nets. We
+                * want to only examine the local ones.
+                */
+               if (!lnet_get_net_locked(peer_net->lpn_net_id))
+                       continue;
+               best_ni = lnet_find_best_ni_on_spec_net(best_ni, peer,
+                                                  peer_net, md_cpt, false);
+       }
+
+       if (best_ni)
+               /* increment sequence number so we can round robin */
+               best_ni->ni_seq++;
+
+       return best_ni;
+}
+
+static struct lnet_ni *
+lnet_find_existing_preferred_best_ni(struct lnet_send_data *sd)
+{
+       struct lnet_ni *best_ni = NULL;
+       struct lnet_peer_net *peer_net;
+       struct lnet_peer *peer = sd->sd_peer;
+       struct lnet_peer_ni *best_lpni = sd->sd_best_lpni;
+       struct lnet_peer_ni *lpni;
+       int cpt = sd->sd_cpt;
+
+       /*
+        * We must use a consistent source address when sending to a
+        * non-MR peer. However, a non-MR peer can have multiple NIDs
+        * on multiple networks, and we may even need to talk to this
+        * peer on multiple networks -- certain types of
+        * load-balancing configuration do this.
+        *
+        * So we need to pick the NI the peer prefers for this
+        * particular network.
+        */
+
+       /* Get the target peer_ni */
+       peer_net = lnet_peer_get_net_locked(peer,
+                       LNET_NIDNET(best_lpni->lpni_nid));
+       LASSERT(peer_net != NULL);
+       list_for_each_entry(lpni, &peer_net->lpn_peer_nis,
+                               lpni_peer_nis) {
+               if (lpni->lpni_pref_nnids == 0)
+                       continue;
+               LASSERT(lpni->lpni_pref_nnids == 1);
+               best_ni = lnet_nid2ni_locked(
+                               lpni->lpni_pref.nid, cpt);
+               break;
+       }
+
+       return best_ni;
+}
+
+/* Prerequisite: sd->sd_peer and sd->sd_best_lpni should be set */
+static int
+lnet_select_preferred_best_ni(struct lnet_send_data *sd)
+{
+       struct lnet_ni *best_ni = NULL;
+       struct lnet_peer_ni *best_lpni = sd->sd_best_lpni;
+
+       /*
+        * We must use a consistent source address when sending to a
+        * non-MR peer. However, a non-MR peer can have multiple NIDs
+        * on multiple networks, and we may even need to talk to this
+        * peer on multiple networks -- certain types of
+        * load-balancing configuration do this.
+        *
+        * So we need to pick the NI the peer prefers for this
+        * particular network.
+        */
+
+       best_ni = lnet_find_existing_preferred_best_ni(sd);
+
+       /* if best_ni is still not set just pick one */
+       if (!best_ni) {
+               best_ni =
+                 lnet_find_best_ni_on_spec_net(NULL, sd->sd_peer,
+                                               sd->sd_best_lpni->lpni_peer_net,
+                                               sd->sd_md_cpt, true);
+               /* If there is no best_ni we don't have a route */
+               if (!best_ni) {
+                       CERROR("no path to %s from net %s\n",
+                               libcfs_nid2str(best_lpni->lpni_nid),
+                               libcfs_net2str(best_lpni->lpni_net->net_id));
+                       return -EHOSTUNREACH;
+               }
+       }
+
+       sd->sd_best_ni = best_ni;
+
+       /* Set preferred NI if necessary. */
+       lnet_set_non_mr_pref_nid(sd);
+
+       return 0;
+}
+
+
+/*
+ * Source not specified
+ * Local destination
+ * Non-MR Peer
+ *
+ * always use the same source NID for NMR peers
+ * If we've talked to that peer before then we already have a preferred
+ * source NI associated with it. Otherwise, we select a preferred local NI
+ * and store it in the peer
+ */
+static int
+lnet_handle_any_local_nmr_dst(struct lnet_send_data *sd)
+{
+       int rc;
+
+       /* sd->sd_best_lpni is already set to the final destination */
+
+       /*
+        * At this point we should've created the peer ni and peer. If we
+        * can't find it, then something went wrong. Instead of assert
+        * output a relevant message and fail the send
+        */
+       if (!sd->sd_best_lpni) {
+               CERROR("Internal fault. Unable to send msg %s to %s. "
+                      "NID not known\n",
+                      lnet_msgtyp2str(sd->sd_msg->msg_type),
+                      libcfs_nid2str(sd->sd_dst_nid));
+               return -EFAULT;
+       }
+
+       rc = lnet_select_preferred_best_ni(sd);
+       if (!rc)
+               rc = lnet_handle_send(sd);
+
+       return rc;
+}
+
+static int
+lnet_handle_any_mr_dsta(struct lnet_send_data *sd)
+{
+       /*
+        * NOTE we've already handled the remote peer case. So we only
+        * need to worry about the local case here.
+        *
+        * if we're sending a response, ACK or reply, we need to send it
+        * to the destination NID given to us. At this point we already
+        * have the peer_ni we're suppose to send to, so just find the
+        * best_ni on the peer net and use that. Since we're sending to an
+        * MR peer then we can just run the selection algorithm on our
+        * local NIs and pick the best one.
+        */
+       if (sd->sd_send_case & SND_RESP) {
+               sd->sd_best_ni =
+                 lnet_find_best_ni_on_spec_net(NULL, sd->sd_peer,
+                                               sd->sd_best_lpni->lpni_peer_net,
+                                               sd->sd_md_cpt, true);
+
+               if (!sd->sd_best_ni) {
+                       /*
+                        * We're not going to deal with not able to send
+                        * a response to the provided final destination
+                        */
+                       CERROR("Can't send response to %s. "
+                              "No local NI available\n",
+                               libcfs_nid2str(sd->sd_dst_nid));
+                       return -EHOSTUNREACH;
+               }
+
+               return lnet_handle_send(sd);
+       }
+
+       /*
+        * If we get here that means we're sending a fresh request, PUT or
+        * GET, so we need to run our standard selection algorithm.
+        * First find the best local interface that's on any of the peer's
+        * networks.
+        */
+       sd->sd_best_ni = lnet_find_best_ni_on_local_net(sd->sd_peer,
+                                                       sd->sd_md_cpt);
+       if (sd->sd_best_ni) {
+               sd->sd_best_lpni =
+                 lnet_find_best_lpni_on_net(sd, sd->sd_peer,
+                                            sd->sd_best_ni->ni_net->net_id);
+
+               /*
+                * if we're successful in selecting a peer_ni on the local
+                * network, then send to it. Otherwise fall through and
+                * try and see if we can reach it over another routed
+                * network
+                */
+               if (sd->sd_best_lpni) {
+                       /*
+                        * in case we initially started with a routed
+                        * destination, let's reset to local
+                        */
+                       sd->sd_send_case &= ~REMOTE_DST;
+                       sd->sd_send_case |= LOCAL_DST;
+                       return lnet_handle_send(sd);
+               }
+
+               CERROR("Internal Error. Expected to have a best_lpni: "
+                      "%s -> %s\n",
+                      libcfs_nid2str(sd->sd_src_nid),
+                      libcfs_nid2str(sd->sd_dst_nid));
+
+               return -EFAULT;
+       }
+
+       /*
+        * Peer doesn't have a local network. Let's see if there is
+        * a remote network we can reach it on.
+        */
+       return PASS_THROUGH;
+}
+
+/*
+ * Case 1:
+ *     Source NID not specified
+ *     Local destination
+ *     MR peer
+ *
+ * Case 2:
+ *     Source NID not speified
+ *     Remote destination
+ *     MR peer
+ *
+ * In both of these cases if we're sending a response, ACK or REPLY, then
+ * we need to send to the destination NID provided.
+ *
+ * In the remote case let's deal with MR routers.
+ *
+ */
+
+static int
+lnet_handle_any_mr_dst(struct lnet_send_data *sd)
+{
+       int rc = 0;
+       struct lnet_peer *gw_peer = NULL;
+       struct lnet_peer_ni *gw_lpni = NULL;
+
+       /*
+        * handle sending a response to a remote peer here so we don't
+        * have to worry about it if we hit lnet_handle_any_mr_dsta()
+        */
+       if (sd->sd_send_case & REMOTE_DST &&
+           sd->sd_send_case & SND_RESP) {
+               struct lnet_peer_ni *gw;
+               struct lnet_peer *gw_peer;
+
+               rc = lnet_handle_find_routed_path(sd, sd->sd_dst_nid, &gw,
+                                                 &gw_peer);
+               if (rc < 0) {
+                       CERROR("Can't send response to %s. "
+                              "No route available\n",
+                               libcfs_nid2str(sd->sd_dst_nid));
+                       return -EHOSTUNREACH;
+               }
+
+               sd->sd_best_lpni = gw;
+               sd->sd_peer = gw_peer;
+
+               return lnet_handle_send(sd);
+       }
+
+       /*
+        * Even though the NID for the peer might not be on a local network,
+        * since the peer is MR there could be other interfaces on the
+        * local network. In that case we'd still like to prefer the local
+        * network over the routed network. If we're unable to do that
+        * then we select the best router among the different routed networks,
+        * and if the router is MR then we can deal with it as such.
+        */
+       rc = lnet_handle_any_mr_dsta(sd);
+       if (rc != PASS_THROUGH)
+               return rc;
+
+       /*
+        * TODO; One possible enhancement is to run the selection
+        * algorithm on the peer. However for remote peers the credits are
+        * not decremented, so we'll be basically going over the peer NIs
+        * in round robin. An MR router will run the selection algorithm
+        * on the next-hop interfaces.
+        */
+       rc = lnet_handle_find_routed_path(sd, sd->sd_dst_nid, &gw_lpni,
+                                         &gw_peer);
+       if (rc < 0)
+               return rc;
+
+       sd->sd_send_case &= ~LOCAL_DST;
+       sd->sd_send_case |= REMOTE_DST;
+
+       sd->sd_peer = gw_peer;
+       sd->sd_best_lpni = gw_lpni;
+
+       return lnet_handle_send(sd);
+}
+
+/*
+ * Source not specified
+ * Remote destination
+ * Non-MR peer
+ *
+ * Must send to the specified peer NID using the same source NID that
+ * we've used before. If it's the first time to talk to that peer then
+ * find the source NI and assign it as preferred to that peer
+ */
+static int
+lnet_handle_any_router_nmr_dst(struct lnet_send_data *sd)
+{
+       int rc;
+       struct lnet_peer_ni *gw_lpni = NULL;
+       struct lnet_peer *gw_peer = NULL;
+
+       /*
+        * Let's set if we have a preferred NI to talk to this NMR peer
+        */
+       sd->sd_best_ni = lnet_find_existing_preferred_best_ni(sd);
+
+       /*
+        * find the router and that'll find the best NI if we didn't find
+        * it already.
+        */
+       rc = lnet_handle_find_routed_path(sd, sd->sd_dst_nid, &gw_lpni,
+                                         &gw_peer);
+       if (rc < 0)
+               return rc;
+
+       /*
+        * set the best_ni we've chosen as the preferred one for
+        * this peer
+        */
+       lnet_set_non_mr_pref_nid(sd);
+
+       /* we'll be sending to the gw */
+       sd->sd_best_lpni = gw_lpni;
+       sd->sd_peer = gw_peer;
+
+       return lnet_handle_send(sd);
+}
+
+static int
+lnet_handle_send_case_locked(struct lnet_send_data *sd)
+{
+       /*
+        * turn off the SND_RESP bit.
+        * It will be checked in the case handling
+        */
+       __u32 send_case = sd->sd_send_case &= ~SND_RESP ;
+
+       CDEBUG(D_NET, "Source %s%s to %s %s %s destination\n",
+               (send_case & SRC_SPEC) ? "Specified: " : "ANY",
+               (send_case & SRC_SPEC) ? libcfs_nid2str(sd->sd_src_nid) : "",
+               (send_case & MR_DST) ? "MR: " : "NMR: ",
+               libcfs_nid2str(sd->sd_dst_nid),
+               (send_case & LOCAL_DST) ? "local" : "routed");
+
+       switch (send_case) {
+       /*
+        * For all cases where the source is specified, we should always
+        * use the destination NID, whether it's an MR destination or not,
+        * since we're continuing a series of related messages for the
+        * same RPC
+        */
+       case SRC_SPEC_LOCAL_NMR_DST:
+               return lnet_handle_spec_local_nmr_dst(sd);
+       case SRC_SPEC_LOCAL_MR_DST:
+               return lnet_handle_spec_local_mr_dst(sd);
+       case SRC_SPEC_ROUTER_NMR_DST:
+       case SRC_SPEC_ROUTER_MR_DST:
+               return lnet_handle_spec_router_dst(sd);
+       case SRC_ANY_LOCAL_NMR_DST:
+               return lnet_handle_any_local_nmr_dst(sd);
+       case SRC_ANY_LOCAL_MR_DST:
+       case SRC_ANY_ROUTER_MR_DST:
+               return lnet_handle_any_mr_dst(sd);
+       case SRC_ANY_ROUTER_NMR_DST:
+               return lnet_handle_any_router_nmr_dst(sd);
+       default:
+               CERROR("Unknown send case\n");
+               return -1;
+       }
+}
+
+static int
+lnet_select_pathway(lnet_nid_t src_nid, lnet_nid_t dst_nid,
+                   struct lnet_msg *msg, lnet_nid_t rtr_nid)
+{
+       struct lnet_peer_ni     *lpni;
+       struct lnet_peer        *peer;
+       struct lnet_send_data   send_data;
+       int                     cpt, rc;
+       int                     md_cpt;
+       __u32                   send_case = 0;
+
+       memset(&send_data, 0, sizeof(send_data));
+
+       /*
+        * get an initial CPT to use for locking. The idea here is not to
+        * serialize the calls to select_pathway, so that as many
+        * operations can run concurrently as possible. To do that we use
+        * the CPT where this call is being executed. Later on when we
+        * determine the CPT to use in lnet_message_commit, we switch the
+        * lock and check if there was any configuration change.  If none,
+        * then we proceed, if there is, then we restart the operation.
+        */
+       cpt = lnet_net_lock_current();
+
+       md_cpt = lnet_cpt_of_md(msg->msg_md, msg->msg_offset);
+       if (md_cpt == CFS_CPT_ANY)
+               md_cpt = cpt;
+
+again:
+
+       /*
+        * If we're being asked to send to the loopback interface, there
+        * is no need to go through any selection. We can just shortcut
+        * the entire process and send over lolnd
+        */
+       if (LNET_NETTYP(LNET_NIDNET(dst_nid)) == LOLND) {
+               /* No send credit hassles with LOLND */
+               lnet_ni_addref_locked(the_lnet.ln_loni, cpt);
+               msg->msg_hdr.dest_nid = cpu_to_le64(the_lnet.ln_loni->ni_nid);
+               if (!msg->msg_routing)
+                       msg->msg_hdr.src_nid =
+                               cpu_to_le64(the_lnet.ln_loni->ni_nid);
+               msg->msg_target.nid = the_lnet.ln_loni->ni_nid;
+               lnet_msg_commit(msg, cpt);
+               msg->msg_txni = the_lnet.ln_loni;
+               lnet_net_unlock(cpt);
+
+               return LNET_CREDIT_OK;
+       }
+
+       /*
+        * find an existing peer_ni, or create one and mark it as having been
+        * created due to network traffic. This call will create the
+        * peer->peer_net->peer_ni tree.
+        */
+       lpni = lnet_nid2peerni_locked(dst_nid, LNET_NID_ANY, cpt);
+       if (IS_ERR(lpni)) {
+               lnet_net_unlock(cpt);
+               return PTR_ERR(lpni);
+       }
+
+       /*
+        * Cache the original src_nid. If we need to resend the message
+        * then we'll need to know whether the src_nid was originally
+        * specified for this message. If it was originally specified,
+        * then we need to keep using the same src_nid since it's
+        * continuing the same sequence of messages.
+        */
+       msg->msg_src_nid_param = src_nid;
+
+       /*
+        * Now that we have a peer_ni, check if we want to discover
+        * the peer. Traffic to the LNET_RESERVED_PORTAL should not
+        * trigger discovery.
+        */
+       peer = lpni->lpni_peer_net->lpn_peer;
+       if (lnet_msg_discovery(msg) && !lnet_peer_is_uptodate(peer)) {
+               lnet_nid_t primary_nid;
+               rc = lnet_discover_peer_locked(lpni, cpt, false);
+               if (rc) {
+                       lnet_peer_ni_decref_locked(lpni);
+                       lnet_net_unlock(cpt);
+                       return rc;
+               }
+               /* The peer may have changed. */
+               peer = lpni->lpni_peer_net->lpn_peer;
+               /* queue message and return */
+               msg->msg_rtr_nid_param = rtr_nid;
+               msg->msg_sending = 0;
+               list_add_tail(&msg->msg_list, &peer->lp_dc_pendq);
+               lnet_peer_ni_decref_locked(lpni);
+               primary_nid = peer->lp_primary_nid;
+               lnet_net_unlock(cpt);
+
+               CDEBUG(D_NET, "%s pending discovery\n",
+                      libcfs_nid2str(primary_nid));
+
+               return LNET_DC_WAIT;
+       }
+       lnet_peer_ni_decref_locked(lpni);
+
+       /*
+        * Identify the different send cases
+        */
+       if (src_nid == LNET_NID_ANY)
+               send_case |= SRC_ANY;
+       else
+               send_case |= SRC_SPEC;
+
+       if (lnet_get_net_locked(LNET_NIDNET(dst_nid)))
+               send_case |= LOCAL_DST;
+       else
+               send_case |= REMOTE_DST;
+
+       /*
+        * if this is a non-MR peer or if we're recovering a peer ni then
+        * let's consider this an NMR case so we can hit the destination
+        * NID.
+        */
+       if (!lnet_peer_is_multi_rail(peer) || msg->msg_recovery)
+               send_case |= NMR_DST;
+       else
+               send_case |= MR_DST;
+
+       if (msg->msg_type == LNET_MSG_REPLY ||
+           msg->msg_type == LNET_MSG_ACK)
+               send_case |= SND_RESP;
+
+       /* assign parameters to the send_data */
+       send_data.sd_msg = msg;
+       send_data.sd_rtr_nid = rtr_nid;
+       send_data.sd_src_nid = src_nid;
+       send_data.sd_dst_nid = dst_nid;
+       send_data.sd_best_lpni = lpni;
+       /*
+        * keep a pointer to the final destination in case we're going to
+        * route, so we'll need to access it later
+        */
+       send_data.sd_final_dst_lpni = lpni;
+       send_data.sd_peer = peer;
+       send_data.sd_md_cpt = md_cpt;
+       send_data.sd_cpt = cpt;
+       send_data.sd_send_case = send_case;
+
+       rc = lnet_handle_send_case_locked(&send_data);
+
+       if (rc == REPEAT_SEND)
+               goto again;
+
+       lnet_net_unlock(send_data.sd_cpt);
+
+       return rc;
+}
+
+int
+lnet_send(lnet_nid_t src_nid, struct lnet_msg *msg, lnet_nid_t rtr_nid)
+{
+       lnet_nid_t              dst_nid = msg->msg_target.nid;
+       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 != NULL == interface pre-determined (ACK/REPLY) */
+       LASSERT(msg->msg_txpeer == NULL);
+       LASSERT(msg->msg_txni == NULL);
+       LASSERT(!msg->msg_sending);
+       LASSERT(!msg->msg_target_is_router);
+       LASSERT(!msg->msg_receiving);
+
+       msg->msg_sending = 1;
+
+       LASSERT(!msg->msg_tx_committed);
+
+       rc = lnet_select_pathway(src_nid, dst_nid, msg, rtr_nid);
+       if (rc < 0)
+               return rc;
+
+       if (rc == LNET_CREDIT_OK)
+               lnet_ni_send(msg->msg_txni, msg);
+
+       /* rc == LNET_CREDIT_OK or LNET_CREDIT_WAIT or LNET_DC_WAIT */
+       return 0;
+}
+
+enum lnet_mt_event_type {
+       MT_TYPE_LOCAL_NI = 0,
+       MT_TYPE_PEER_NI
+};
+
+struct lnet_mt_event_info {
+       enum lnet_mt_event_type mt_type;
+       lnet_nid_t mt_nid;
+};
+
+void
+lnet_detach_rsp_tracker(struct lnet_libmd *md, int cpt)
+{
+       struct lnet_rsp_tracker *rspt;
+
+       /*
+        * msg has a refcount on the MD so the MD is not going away.
+        * The rspt queue for the cpt is protected by
+        * the lnet_net_lock(cpt). cpt is the cpt of the MD cookie.
+        */
+       lnet_res_lock(cpt);
+       if (!md->md_rspt_ptr) {
+               lnet_res_unlock(cpt);
+               return;
+       }
+       rspt = md->md_rspt_ptr;
+       md->md_rspt_ptr = NULL;
+
+       /* debug code */
+       LASSERT(rspt->rspt_cpt == cpt);
+
+       /*
+        * invalidate the handle to indicate that a response has been
+        * received, which will then lead the monitor thread to clean up
+        * the rspt block.
+        */
+       LNetInvalidateMDHandle(&rspt->rspt_mdh);
+       lnet_res_unlock(cpt);
+}
+
+static void
+lnet_finalize_expired_responses(bool force)
+{
+       struct lnet_libmd *md;
+       struct list_head local_queue;
+       struct lnet_rsp_tracker *rspt, *tmp;
+       int i;
+
+       if (the_lnet.ln_mt_rstq == NULL)
+               return;
+
+       cfs_cpt_for_each(i, lnet_cpt_table()) {
+               INIT_LIST_HEAD(&local_queue);
+
+               lnet_net_lock(i);
+               if (!the_lnet.ln_mt_rstq[i]) {
+                       lnet_net_unlock(i);
+                       continue;
+               }
+               list_splice_init(the_lnet.ln_mt_rstq[i], &local_queue);
+               lnet_net_unlock(i);
+
+               list_for_each_entry_safe(rspt, tmp, &local_queue, rspt_on_list) {
+                       /*
+                        * The rspt mdh will be invalidated when a response
+                        * is received or whenever we want to discard the
+                        * block the monitor thread will walk the queue
+                        * and clean up any rsts with an invalid mdh.
+                        * The monitor thread will walk the queue until
+                        * the first unexpired rspt block. This means that
+                        * some rspt blocks which received their
+                        * corresponding responses will linger in the
+                        * queue until they are cleaned up eventually.
+                        */
+                       lnet_res_lock(i);
+                       if (LNetMDHandleIsInvalid(rspt->rspt_mdh)) {
+                               lnet_res_unlock(i);
+                               list_del_init(&rspt->rspt_on_list);
+                               lnet_rspt_free(rspt, i);
+                               continue;
+                       }
+
+                       if (ktime_compare(ktime_get(), rspt->rspt_deadline) >= 0 ||
+                           force) {
+                               md = lnet_handle2md(&rspt->rspt_mdh);
+                               if (!md) {
+                                       LNetInvalidateMDHandle(&rspt->rspt_mdh);
+                                       lnet_res_unlock(i);
+                                       list_del_init(&rspt->rspt_on_list);
+                                       lnet_rspt_free(rspt, i);
+                                       continue;
+                               }
+                               LASSERT(md->md_rspt_ptr == rspt);
+                               md->md_rspt_ptr = NULL;
+                               lnet_res_unlock(i);
+
+                               lnet_net_lock(i);
+                               the_lnet.ln_counters[i]->response_timeout_count++;
+                               lnet_net_unlock(i);
+
+                               list_del_init(&rspt->rspt_on_list);
+
+                               CDEBUG(D_NET, "Response timed out: md = %p\n", md);
+                               LNetMDUnlink(rspt->rspt_mdh);
+                               lnet_rspt_free(rspt, i);
+                       } else {
+                               lnet_res_unlock(i);
+                               break;
+                       }
+               }
+
+               lnet_net_lock(i);
+               if (!list_empty(&local_queue))
+                       list_splice(&local_queue, the_lnet.ln_mt_rstq[i]);
+               lnet_net_unlock(i);
+       }
+}
+
+static void
+lnet_resend_pending_msgs_locked(struct list_head *resendq, int cpt)
+{
+       struct lnet_msg *msg;
+
+       while (!list_empty(resendq)) {
+               struct lnet_peer_ni *lpni;
+
+               msg = list_entry(resendq->next, struct lnet_msg,
+                                msg_list);
+
+               list_del_init(&msg->msg_list);
+
+               lpni = lnet_find_peer_ni_locked(msg->msg_hdr.dest_nid);
+               if (!lpni) {
+                       lnet_net_unlock(cpt);
+                       CERROR("Expected that a peer is already created for %s\n",
+                              libcfs_nid2str(msg->msg_hdr.dest_nid));
+                       msg->msg_no_resend = true;
+                       lnet_finalize(msg, -EFAULT);
+                       lnet_net_lock(cpt);
+               } else {
+                       struct lnet_peer *peer;
+                       int rc;
+                       lnet_nid_t src_nid = LNET_NID_ANY;
+
+                       /*
+                        * if this message is not being routed and the
+                        * peer is non-MR then we must use the same
+                        * src_nid that was used in the original send.
+                        * Otherwise if we're routing the message (IE
+                        * we're a router) then we can use any of our
+                        * local interfaces. It doesn't matter to the
+                        * final destination.
+                        */
+                       peer = lpni->lpni_peer_net->lpn_peer;
+                       if (!msg->msg_routing &&
+                           !lnet_peer_is_multi_rail(peer))
+                               src_nid = le64_to_cpu(msg->msg_hdr.src_nid);
+
+                       /*
+                        * If we originally specified a src NID, then we
+                        * must attempt to reuse it in the resend as well.
+                        */
+                       if (msg->msg_src_nid_param != LNET_NID_ANY)
+                               src_nid = msg->msg_src_nid_param;
+                       lnet_peer_ni_decref_locked(lpni);
+
+                       lnet_net_unlock(cpt);
+                       CDEBUG(D_NET, "resending %s->%s: %s recovery %d\n",
+                              libcfs_nid2str(src_nid),
+                              libcfs_id2str(msg->msg_target),
+                              lnet_msgtyp2str(msg->msg_type),
+                              msg->msg_recovery);
+                       rc = lnet_send(src_nid, msg, LNET_NID_ANY);
+                       if (rc) {
+                               CERROR("Error sending %s to %s: %d\n",
+                                      lnet_msgtyp2str(msg->msg_type),
+                                      libcfs_id2str(msg->msg_target), rc);
+                               msg->msg_no_resend = true;
+                               lnet_finalize(msg, rc);
+                       }
+                       lnet_net_lock(cpt);
+                       if (!rc)
+                               the_lnet.ln_counters[cpt]->resend_count++;
+               }
+       }
+}
+
+static void
+lnet_resend_pending_msgs(void)
+{
+       int i;
+
+       cfs_cpt_for_each(i, lnet_cpt_table()) {
+               lnet_net_lock(i);
+               lnet_resend_pending_msgs_locked(the_lnet.ln_mt_resendqs[i], i);
+               lnet_net_unlock(i);
+       }
+}
+
+/* called with cpt and ni_lock held */
+static void
+lnet_unlink_ni_recovery_mdh_locked(struct lnet_ni *ni, int cpt)
+{
+       struct lnet_handle_md recovery_mdh;
+
+       LNetInvalidateMDHandle(&recovery_mdh);
+
+       if (ni->ni_state & LNET_NI_STATE_RECOVERY_PENDING) {
+               recovery_mdh = ni->ni_ping_mdh;
+               LNetInvalidateMDHandle(&ni->ni_ping_mdh);
+       }
+       lnet_ni_unlock(ni);
+       lnet_net_unlock(cpt);
+       if (!LNetMDHandleIsInvalid(recovery_mdh))
+               LNetMDUnlink(recovery_mdh);
+       lnet_net_lock(cpt);
+       lnet_ni_lock(ni);
+}
+
+static void
+lnet_recover_local_nis(void)
+{
+       struct lnet_mt_event_info *ev_info;
+       struct list_head processed_list;
+       struct list_head local_queue;
+       struct lnet_handle_md mdh;
+       struct lnet_ni *tmp;
+       struct lnet_ni *ni;
+       lnet_nid_t nid;
+       int healthv;
+       int rc;
+
+       INIT_LIST_HEAD(&local_queue);
+       INIT_LIST_HEAD(&processed_list);
+
+       /*
+        * splice the recovery queue on a local queue. We will iterate
+        * through the local queue and update it as needed. Once we're
+        * done with the traversal, we'll splice the local queue back on
+        * the head of the ln_mt_localNIRecovq. Any newly added local NIs
+        * will be traversed in the next iteration.
+        */
+       lnet_net_lock(0);
+       list_splice_init(&the_lnet.ln_mt_localNIRecovq,
+                        &local_queue);
+       lnet_net_unlock(0);
+
+       list_for_each_entry_safe(ni, tmp, &local_queue, ni_recovery) {
+               /*
+                * if an NI is being deleted or it is now healthy, there
+                * is no need to keep it around in the recovery queue.
+                * The monitor thread is the only thread responsible for
+                * removing the NI from the recovery queue.
+                * Multiple threads can be adding NIs to the recovery
+                * queue.
+                */
+               healthv = atomic_read(&ni->ni_healthv);
+
+               lnet_net_lock(0);
+               lnet_ni_lock(ni);
+               if (!(ni->ni_state & LNET_NI_STATE_ACTIVE) ||
+                   healthv == LNET_MAX_HEALTH_VALUE) {
+                       list_del_init(&ni->ni_recovery);
+                       lnet_unlink_ni_recovery_mdh_locked(ni, 0);
+                       lnet_ni_unlock(ni);
+                       lnet_ni_decref_locked(ni, 0);
+                       lnet_net_unlock(0);
+                       continue;
+               }
+               lnet_ni_unlock(ni);
+               lnet_net_unlock(0);
+
+
+               CDEBUG(D_NET, "attempting to recover local ni: %s\n",
+                      libcfs_nid2str(ni->ni_nid));
+
+               lnet_ni_lock(ni);
+               if (!(ni->ni_state & LNET_NI_STATE_RECOVERY_PENDING)) {
+                       ni->ni_state |= LNET_NI_STATE_RECOVERY_PENDING;
+                       lnet_ni_unlock(ni);
+
+                       LIBCFS_ALLOC(ev_info, sizeof(*ev_info));
+                       if (!ev_info) {
+                               CERROR("out of memory. Can't recover %s\n",
+                                      libcfs_nid2str(ni->ni_nid));
+                               lnet_ni_lock(ni);
+                               ni->ni_state &= ~LNET_NI_STATE_RECOVERY_PENDING;
+                               lnet_ni_unlock(ni);
+                               continue;
+                       }
+
+                       mdh = ni->ni_ping_mdh;
+                       /*
+                        * Invalidate the ni mdh in case it's deleted.
+                        * We'll unlink the mdh in this case below.
+                        */
+                       LNetInvalidateMDHandle(&ni->ni_ping_mdh);
+                       nid = ni->ni_nid;
+
+                       /*
+                        * remove the NI from the local queue and drop the
+                        * reference count to it while we're recovering
+                        * it. The reason for that, is that the NI could
+                        * be deleted, and the way the code is structured
+                        * is if we don't drop the NI, then the deletion
+                        * code will enter a loop waiting for the
+                        * reference count to be removed while holding the
+                        * ln_mutex_lock(). When we look up the peer to
+                        * send to in lnet_select_pathway() we will try to
+                        * lock the ln_mutex_lock() as well, leading to
+                        * a deadlock. By dropping the refcount and
+                        * removing it from the list, we allow for the NI
+                        * to be removed, then we use the cached NID to
+                        * look it up again. If it's gone, then we just
+                        * continue examining the rest of the queue.
+                        */
+                       lnet_net_lock(0);
+                       list_del_init(&ni->ni_recovery);
+                       lnet_ni_decref_locked(ni, 0);
+                       lnet_net_unlock(0);
+
+                       ev_info->mt_type = MT_TYPE_LOCAL_NI;
+                       ev_info->mt_nid = nid;
+                       rc = lnet_send_ping(nid, &mdh, LNET_INTERFACES_MIN,
+                                           ev_info, the_lnet.ln_mt_eqh, true);
+                       /* lookup the nid again */
+                       lnet_net_lock(0);
+                       ni = lnet_nid2ni_locked(nid, 0);
+                       if (!ni) {
+                               /*
+                                * the NI has been deleted when we dropped
+                                * the ref count
+                                */
+                               lnet_net_unlock(0);
+                               LNetMDUnlink(mdh);
+                               continue;
+                       }
+                       /*
+                        * Same note as in lnet_recover_peer_nis(). When
+                        * we're sending the ping, the NI is free to be
+                        * deleted or manipulated. By this point it
+                        * could've been added back on the recovery queue,
+                        * and a refcount taken on it.
+                        * So we can't just add it blindly again or we'll
+                        * corrupt the queue. We must check under lock if
+                        * it's not on any list and if not then add it
+                        * to the processed list, which will eventually be
+                        * spliced back on to the recovery queue.
+                        */
+                       ni->ni_ping_mdh = mdh;
+                       if (list_empty(&ni->ni_recovery)) {
+                               list_add_tail(&ni->ni_recovery, &processed_list);
+                               lnet_ni_addref_locked(ni, 0);
+                       }
+                       lnet_net_unlock(0);
+
+                       lnet_ni_lock(ni);
+                       if (rc)
+                               ni->ni_state &= ~LNET_NI_STATE_RECOVERY_PENDING;
+               }
+               lnet_ni_unlock(ni);
+       }
+
+       /*
+        * put back the remaining NIs on the ln_mt_localNIRecovq to be
+        * reexamined in the next iteration.
+        */
+       list_splice_init(&processed_list, &local_queue);
+       lnet_net_lock(0);
+       list_splice(&local_queue, &the_lnet.ln_mt_localNIRecovq);
+       lnet_net_unlock(0);
+}
+
+static struct list_head **
+lnet_create_array_of_queues(void)
+{
+       struct list_head **qs;
+       struct list_head *q;
+       int i;
+
+       qs = cfs_percpt_alloc(lnet_cpt_table(),
+                             sizeof(struct list_head));
+       if (!qs) {
+               CERROR("Failed to allocate queues\n");
+               return NULL;
        }
+
+       cfs_percpt_for_each(q, i, qs)
+               INIT_LIST_HEAD(q);
+
+       return qs;
 }
 
 static int
-lnet_compare_routes(lnet_route_t *r1, lnet_route_t *r2)
+lnet_resendqs_create(void)
 {
-       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;
+       struct list_head **resendqs;
+       resendqs = lnet_create_array_of_queues();
 
-       if (r1->lr_priority < r2->lr_priority)
-               return 1;
+       if (!resendqs)
+               return -ENOMEM;
 
-       if (r1->lr_priority > r2->lr_priority)
-               return -ERANGE;
+       lnet_net_lock(LNET_LOCK_EX);
+       the_lnet.ln_mt_resendqs = resendqs;
+       lnet_net_unlock(LNET_LOCK_EX);
 
-       if (r1_hops < r2_hops)
-               return 1;
+       return 0;
+}
 
-       if (r1_hops > r2_hops)
-               return -ERANGE;
+static void
+lnet_clean_local_ni_recoveryq(void)
+{
+       struct lnet_ni *ni;
 
-       if (p1->lp_txqnob < p2->lp_txqnob)
-               return 1;
+       /* This is only called when the monitor thread has stopped */
+       lnet_net_lock(0);
 
-       if (p1->lp_txqnob > p2->lp_txqnob)
-               return -ERANGE;
+       while (!list_empty(&the_lnet.ln_mt_localNIRecovq)) {
+               ni = list_entry(the_lnet.ln_mt_localNIRecovq.next,
+                               struct lnet_ni, ni_recovery);
+               list_del_init(&ni->ni_recovery);
+               lnet_ni_lock(ni);
+               lnet_unlink_ni_recovery_mdh_locked(ni, 0);
+               lnet_ni_unlock(ni);
+               lnet_ni_decref_locked(ni, 0);
+       }
 
-       if (p1->lp_txcredits > p2->lp_txcredits)
-               return 1;
+       lnet_net_unlock(0);
+}
 
-       if (p1->lp_txcredits < p2->lp_txcredits)
-               return -ERANGE;
+static void
+lnet_unlink_lpni_recovery_mdh_locked(struct lnet_peer_ni *lpni, int cpt)
+{
+       struct lnet_handle_md recovery_mdh;
 
-       if (r1->lr_seq - r2->lr_seq <= 0)
-               return 1;
+       LNetInvalidateMDHandle(&recovery_mdh);
 
-       return -ERANGE;
+       if (lpni->lpni_state & LNET_PEER_NI_RECOVERY_PENDING) {
+               recovery_mdh = lpni->lpni_recovery_ping_mdh;
+               LNetInvalidateMDHandle(&lpni->lpni_recovery_ping_mdh);
+       }
+       spin_unlock(&lpni->lpni_lock);
+       lnet_net_unlock(cpt);
+       if (!LNetMDHandleIsInvalid(recovery_mdh))
+               LNetMDUnlink(recovery_mdh);
+       lnet_net_lock(cpt);
+       spin_lock(&lpni->lpni_lock);
 }
 
-static lnet_peer_t *
-lnet_find_route_locked(lnet_ni_t *ni, lnet_nid_t target, lnet_nid_t rtr_nid)
+static void
+lnet_clean_peer_ni_recoveryq(void)
 {
-       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;
+       struct lnet_peer_ni *lpni, *tmp;
 
-       /* If @rtr_nid is not LNET_NID_ANY, return the gateway with
-        * rtr_nid nid, otherwise find the best gateway I can use */
+       lnet_net_lock(LNET_LOCK_EX);
 
-       rnet = lnet_find_net_locked(LNET_NIDNET(target));
-       if (rnet == NULL)
-               return NULL;
+       list_for_each_entry_safe(lpni, tmp, &the_lnet.ln_mt_peerNIRecovq,
+                                lpni_recovery) {
+               list_del_init(&lpni->lpni_recovery);
+               spin_lock(&lpni->lpni_lock);
+               lnet_unlink_lpni_recovery_mdh_locked(lpni, LNET_LOCK_EX);
+               spin_unlock(&lpni->lpni_lock);
+               lnet_peer_ni_decref_locked(lpni);
+       }
 
-       lp_best = NULL;
-       best_route = last_route = NULL;
-       list_for_each_entry(route, &rnet->lrn_routes, lr_list) {
-               lp = route->lr_gateway;
+       lnet_net_unlock(LNET_LOCK_EX);
+}
 
-               if (!lnet_is_route_alive(route))
-                       continue;
+static void
+lnet_clean_resendqs(void)
+{
+       struct lnet_msg *msg, *tmp;
+       struct list_head msgs;
+       int i;
+
+       INIT_LIST_HEAD(&msgs);
+
+       cfs_cpt_for_each(i, lnet_cpt_table()) {
+               lnet_net_lock(i);
+               list_splice_init(the_lnet.ln_mt_resendqs[i], &msgs);
+               lnet_net_unlock(i);
+               list_for_each_entry_safe(msg, tmp, &msgs, msg_list) {
+                       list_del_init(&msg->msg_list);
+                       msg->msg_no_resend = true;
+                       lnet_finalize(msg, -ESHUTDOWN);
+               }
+       }
 
-               if (ni != NULL && lp->lp_ni != ni)
-                       continue;
+       cfs_percpt_free(the_lnet.ln_mt_resendqs);
+}
 
-               if (lp->lp_nid == rtr_nid) /* it's pre-determined router */
-                       return lp;
+static void
+lnet_recover_peer_nis(void)
+{
+       struct lnet_mt_event_info *ev_info;
+       struct list_head processed_list;
+       struct list_head local_queue;
+       struct lnet_handle_md mdh;
+       struct lnet_peer_ni *lpni;
+       struct lnet_peer_ni *tmp;
+       lnet_nid_t nid;
+       int healthv;
+       int rc;
+
+       INIT_LIST_HEAD(&local_queue);
+       INIT_LIST_HEAD(&processed_list);
+
+       /*
+        * Always use cpt 0 for locking across all interactions with
+        * ln_mt_peerNIRecovq
+        */
+       lnet_net_lock(0);
+       list_splice_init(&the_lnet.ln_mt_peerNIRecovq,
+                        &local_queue);
+       lnet_net_unlock(0);
 
-               if (lp_best == NULL) {
-                       best_route = last_route = route;
-                       lp_best = lp;
+       list_for_each_entry_safe(lpni, tmp, &local_queue,
+                                lpni_recovery) {
+               /*
+                * The same protection strategy is used here as is in the
+                * local recovery case.
+                */
+               lnet_net_lock(0);
+               healthv = atomic_read(&lpni->lpni_healthv);
+               spin_lock(&lpni->lpni_lock);
+               if (lpni->lpni_state & LNET_PEER_NI_DELETING ||
+                   healthv == LNET_MAX_HEALTH_VALUE) {
+                       list_del_init(&lpni->lpni_recovery);
+                       lnet_unlink_lpni_recovery_mdh_locked(lpni, 0);
+                       spin_unlock(&lpni->lpni_lock);
+                       lnet_peer_ni_decref_locked(lpni);
+                       lnet_net_unlock(0);
                        continue;
                }
+               spin_unlock(&lpni->lpni_lock);
+               lnet_net_unlock(0);
 
-               /* no protection on below fields, but it's harmless */
-               if (last_route->lr_seq - route->lr_seq < 0)
-                       last_route = route;
+               /*
+                * NOTE: we're racing with peer deletion from user space.
+                * It's possible that a peer is deleted after we check its
+                * state. In this case the recovery can create a new peer
+                */
+               spin_lock(&lpni->lpni_lock);
+               if (!(lpni->lpni_state & LNET_PEER_NI_RECOVERY_PENDING) &&
+                   !(lpni->lpni_state & LNET_PEER_NI_DELETING)) {
+                       lpni->lpni_state |= LNET_PEER_NI_RECOVERY_PENDING;
+                       spin_unlock(&lpni->lpni_lock);
+
+                       LIBCFS_ALLOC(ev_info, sizeof(*ev_info));
+                       if (!ev_info) {
+                               CERROR("out of memory. Can't recover %s\n",
+                                      libcfs_nid2str(lpni->lpni_nid));
+                               spin_lock(&lpni->lpni_lock);
+                               lpni->lpni_state &= ~LNET_PEER_NI_RECOVERY_PENDING;
+                               spin_unlock(&lpni->lpni_lock);
+                               continue;
+                       }
 
-               rc = lnet_compare_routes(route, best_route);
-               if (rc < 0)
-                       continue;
+                       /* look at the comments in lnet_recover_local_nis() */
+                       mdh = lpni->lpni_recovery_ping_mdh;
+                       LNetInvalidateMDHandle(&lpni->lpni_recovery_ping_mdh);
+                       nid = lpni->lpni_nid;
+                       lnet_net_lock(0);
+                       list_del_init(&lpni->lpni_recovery);
+                       lnet_peer_ni_decref_locked(lpni);
+                       lnet_net_unlock(0);
+
+                       ev_info->mt_type = MT_TYPE_PEER_NI;
+                       ev_info->mt_nid = nid;
+                       rc = lnet_send_ping(nid, &mdh, LNET_INTERFACES_MIN,
+                                           ev_info, the_lnet.ln_mt_eqh, true);
+                       lnet_net_lock(0);
+                       /*
+                        * lnet_find_peer_ni_locked() grabs a refcount for
+                        * us. No need to take it explicitly.
+                        */
+                       lpni = lnet_find_peer_ni_locked(nid);
+                       if (!lpni) {
+                               lnet_net_unlock(0);
+                               LNetMDUnlink(mdh);
+                               continue;
+                       }
 
-               best_route = route;
-               lp_best = lp;
+                       lpni->lpni_recovery_ping_mdh = mdh;
+                       /*
+                        * While we're unlocked the lpni could've been
+                        * readded on the recovery queue. In this case we
+                        * don't need to add it to the local queue, since
+                        * it's already on there and the thread that added
+                        * it would've incremented the refcount on the
+                        * peer, which means we need to decref the refcount
+                        * that was implicitly grabbed by find_peer_ni_locked.
+                        * Otherwise, if the lpni is still not on
+                        * the recovery queue, then we'll add it to the
+                        * processed list.
+                        */
+                       if (list_empty(&lpni->lpni_recovery))
+                               list_add_tail(&lpni->lpni_recovery, &processed_list);
+                       else
+                               lnet_peer_ni_decref_locked(lpni);
+                       lnet_net_unlock(0);
+
+                       spin_lock(&lpni->lpni_lock);
+                       if (rc)
+                               lpni->lpni_state &= ~LNET_PEER_NI_RECOVERY_PENDING;
+               }
+               spin_unlock(&lpni->lpni_lock);
        }
 
-       /* 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 != NULL)
-               best_route->lr_seq = last_route->lr_seq + 1;
-       return lp_best;
+       list_splice_init(&processed_list, &local_queue);
+       lnet_net_lock(0);
+       list_splice(&local_queue, &the_lnet.ln_mt_peerNIRecovq);
+       lnet_net_unlock(0);
 }
 
-int
-lnet_send(lnet_nid_t src_nid, lnet_msg_t *msg, lnet_nid_t rtr_nid)
+static int
+lnet_monitor_thread(void *arg)
 {
-       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;
+       int wakeup_counter = 0;
+
+       /*
+        * The monitor thread takes care of the following:
+        *  1. Checks the aliveness of routers
+        *  2. Checks if there are messages on the resend queue to resend
+        *     them.
+        *  3. Check if there are any NIs on the local recovery queue and
+        *     pings them
+        *  4. Checks if there are any NIs on the remote recovery queue
+        *     and pings them.
+        */
+       cfs_block_allsigs();
 
-       /* 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 != NULL == interface pre-determined (ACK/REPLY) */
-       LASSERT(msg->msg_txpeer == NULL);
-       LASSERT(!msg->msg_sending);
-       LASSERT(!msg->msg_target_is_router);
-       LASSERT(!msg->msg_receiving);
+       while (the_lnet.ln_mt_state == LNET_MT_STATE_RUNNING) {
+               if (lnet_router_checker_active())
+                       lnet_check_routers();
 
-       msg->msg_sending = 1;
+               lnet_resend_pending_msgs();
 
-       LASSERT(!msg->msg_tx_committed);
-       cpt = lnet_cpt_of_nid(rtr_nid == LNET_NID_ANY ? dst_nid : rtr_nid);
- again:
-       lnet_net_lock(cpt);
+               wakeup_counter++;
+               if (wakeup_counter >= lnet_transaction_timeout / 2) {
+                       lnet_finalize_expired_responses(false);
+                       wakeup_counter = 0;
+               }
 
-       if (the_lnet.ln_shutdown) {
-               lnet_net_unlock(cpt);
-               return -ESHUTDOWN;
+               lnet_recover_local_nis();
+
+               lnet_recover_peer_nis();
+
+               /*
+                * TODO do we need to check if we should sleep without
+                * timeout?  Technically, an active system will always
+                * have messages in flight so this check will always
+                * evaluate to false. And on an idle system do we care
+                * if we wake up every 1 second? Although, we've seen
+                * cases where we get a complaint that an idle thread
+                * is waking up unnecessarily.
+                */
+               wait_event_interruptible_timeout(the_lnet.ln_mt_waitq,
+                                               false,
+                                               cfs_time_seconds(1));
        }
 
-       if (src_nid == LNET_NID_ANY) {
-               src_ni = NULL;
-       } else {
-               src_ni = lnet_nid2ni_locked(src_nid, cpt);
-               if (src_ni == NULL) {
-                       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);
+       /* clean up the router checker */
+       lnet_prune_rc_data(1);
+
+       /* Shutting down */
+       the_lnet.ln_mt_state = LNET_MT_STATE_SHUTDOWN;
+
+       /* signal that the monitor thread is exiting */
+       up(&the_lnet.ln_mt_signal);
+
+       return 0;
+}
+
+/*
+ * lnet_send_ping
+ * Sends a ping.
+ * Returns == 0 if success
+ * Returns > 0 if LNetMDBind or prior fails
+ * Returns < 0 if LNetGet fails
+ */
+int
+lnet_send_ping(lnet_nid_t dest_nid,
+              struct lnet_handle_md *mdh, int nnis,
+              void *user_data, struct lnet_handle_eq eqh, bool recovery)
+{
+       struct lnet_md md = { NULL };
+       struct lnet_process_id id;
+       struct lnet_ping_buffer *pbuf;
+       int rc;
+
+       if (dest_nid == LNET_NID_ANY) {
+               rc = -EHOSTUNREACH;
+               goto fail_error;
        }
 
-       /* Is this for someone on a local network? */
-       local_ni = lnet_net2ni_locked(LNET_NIDNET(dst_nid), cpt);
+       pbuf = lnet_ping_buffer_alloc(nnis, GFP_NOFS);
+       if (!pbuf) {
+               rc = ENOMEM;
+               goto fail_error;
+       }
 
-       if (local_ni != NULL) {
-               if (src_ni == NULL) {
-                       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;
-               }
+       /* initialize md content */
+       md.start     = &pbuf->pb_info;
+       md.length    = LNET_PING_INFO_SIZE(nnis);
+       md.threshold = 2; /* GET/REPLY */
+       md.max_size  = 0;
+       md.options   = LNET_MD_TRUNCATE;
+       md.user_ptr  = user_data;
+       md.eq_handle = eqh;
+
+       rc = LNetMDBind(md, LNET_UNLINK, mdh);
+       if (rc) {
+               lnet_ping_buffer_decref(pbuf);
+               CERROR("Can't bind MD: %d\n", rc);
+               rc = -rc; /* change the rc to positive */
+               goto fail_error;
+       }
+       id.pid = LNET_PID_LUSTRE;
+       id.nid = dest_nid;
 
-               LASSERT(src_nid != LNET_NID_ANY);
-               lnet_msg_commit(msg, cpt);
+       rc = LNetGet(LNET_NID_ANY, *mdh, id,
+                    LNET_RESERVED_PORTAL,
+                    LNET_PROTO_PING_MATCHBITS, 0, recovery);
 
-               if (!msg->msg_routing)
-                       msg->msg_hdr.src_nid = cpu_to_le64(src_nid);
+       if (rc)
+               goto fail_unlink_md;
 
-               if (src_ni == the_lnet.ln_loni) {
-                       /* No send credit hassles with LOLND */
-                       lnet_net_unlock(cpt);
-                       lnet_ni_send(src_ni, msg);
+       return 0;
 
-                       lnet_net_lock(cpt);
-                       lnet_ni_decref_locked(src_ni, cpt);
-                       lnet_net_unlock(cpt);
-                       return 0;
+fail_unlink_md:
+       LNetMDUnlink(*mdh);
+       LNetInvalidateMDHandle(mdh);
+fail_error:
+       return rc;
+}
+
+static void
+lnet_handle_recovery_reply(struct lnet_mt_event_info *ev_info,
+                          int status)
+{
+       lnet_nid_t nid = ev_info->mt_nid;
+
+       if (ev_info->mt_type == MT_TYPE_LOCAL_NI) {
+               struct lnet_ni *ni;
+
+               lnet_net_lock(0);
+               ni = lnet_nid2ni_locked(nid, 0);
+               if (!ni) {
+                       lnet_net_unlock(0);
+                       return;
                }
+               lnet_ni_lock(ni);
+               ni->ni_state &= ~LNET_NI_STATE_RECOVERY_PENDING;
+               lnet_ni_unlock(ni);
+               lnet_net_unlock(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 != 0) {
-                       lnet_net_unlock(cpt);
-                       LCONSOLE_WARN("Error %d finding peer %s\n", rc,
-                                     libcfs_nid2str(dst_nid));
-                       /* ENOMEM or shutting down */
-                       return rc;
+               if (status != 0) {
+                       CERROR("local NI recovery failed with %d\n", status);
+                       return;
                }
-               LASSERT(lp->lp_ni == src_ni);
+               /*
+                * need to increment healthv for the ni here, because in
+                * the lnet_finalize() path we don't have access to this
+                * NI. And in order to get access to it, we'll need to
+                * carry forward too much information.
+                * In the peer case, it'll naturally be incremented
+                */
+               lnet_inc_healthv(&ni->ni_healthv);
        } else {
-               /* sending to a remote network */
-               lp = lnet_find_route_locked(src_ni, dst_nid, rtr_nid);
-               if (lp == NULL) {
-                       if (src_ni != NULL)
-                               lnet_ni_decref_locked(src_ni, cpt);
-                       lnet_net_unlock(cpt);
+               struct lnet_peer_ni *lpni;
+               int cpt;
 
-                       LCONSOLE_WARN("No route to %s via %s "
-                                     "(all routers down)\n",
-                                     libcfs_id2str(msg->msg_target),
-                                     libcfs_nid2str(src_nid));
-                       return -EHOSTUNREACH;
+               cpt = lnet_net_lock_current();
+               lpni = lnet_find_peer_ni_locked(nid);
+               if (!lpni) {
+                       lnet_net_unlock(cpt);
+                       return;
                }
+               spin_lock(&lpni->lpni_lock);
+               lpni->lpni_state &= ~LNET_PEER_NI_RECOVERY_PENDING;
+               spin_unlock(&lpni->lpni_lock);
+               lnet_peer_ni_decref_locked(lpni);
+               lnet_net_unlock(cpt);
 
-               /* 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 != NULL)
-                                       lnet_ni_decref_locked(src_ni, cpt);
-                               lnet_net_unlock(cpt);
-
-                               rtr_nid = lp->lp_nid;
-                               cpt = cpt2;
-                               goto again;
-                       }
-               }
+               if (status != 0)
+                       CERROR("peer NI recovery failed with %d\n", status);
+       }
+}
+
+static void
+lnet_mt_event_handler(struct lnet_event *event)
+{
+       struct lnet_mt_event_info *ev_info = event->md.user_ptr;
+       struct lnet_ping_buffer *pbuf;
+
+       /* TODO: remove assert */
+       LASSERT(event->type == LNET_EVENT_REPLY ||
+               event->type == LNET_EVENT_SEND ||
+               event->type == LNET_EVENT_UNLINK);
+
+       CDEBUG(D_NET, "Received event: %d status: %d\n", event->type,
+              event->status);
+
+       switch (event->type) {
+       case LNET_EVENT_UNLINK:
+               CDEBUG(D_NET, "%s recovery ping unlinked\n",
+                      libcfs_nid2str(ev_info->mt_nid));
+       case LNET_EVENT_REPLY:
+               lnet_handle_recovery_reply(ev_info, event->status);
+               break;
+       case LNET_EVENT_SEND:
+               CDEBUG(D_NET, "%s recovery message sent %s:%d\n",
+                              libcfs_nid2str(ev_info->mt_nid),
+                              (event->status) ? "unsuccessfully" :
+                              "successfully", event->status);
+               break;
+       default:
+               CERROR("Unexpected event: %d\n", event->type);
+               break;
+       }
+       if (event->unlinked) {
+               LIBCFS_FREE(ev_info, sizeof(*ev_info));
+               pbuf = LNET_PING_INFO_TO_BUFFER(event->md.start);
+               lnet_ping_buffer_decref(pbuf);
+       }
+}
 
-               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);
+static int
+lnet_rsp_tracker_create(void)
+{
+       struct list_head **rstqs;
+       rstqs = lnet_create_array_of_queues();
 
-               if (src_ni == NULL) {
-                       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);
-               }
+       if (!rstqs)
+               return -ENOMEM;
 
-               lnet_peer_addref_locked(lp);
+       the_lnet.ln_mt_rstq = rstqs;
 
-               LASSERT(src_nid != LNET_NID_ANY);
-               lnet_msg_commit(msg, cpt);
+       return 0;
+}
 
-               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);
-               }
+static void
+lnet_rsp_tracker_clean(void)
+{
+       lnet_finalize_expired_responses(true);
 
-               msg->msg_target_is_router = 1;
-               msg->msg_target.nid = lp->lp_nid;
-               msg->msg_target.pid = LNET_PID_LUSTRE;
+       cfs_percpt_free(the_lnet.ln_mt_rstq);
+       the_lnet.ln_mt_rstq = NULL;
+}
+
+int lnet_monitor_thr_start(void)
+{
+       int rc = 0;
+       struct task_struct *task;
+
+       if (the_lnet.ln_mt_state != LNET_MT_STATE_SHUTDOWN)
+               return -EALREADY;
+
+       rc = lnet_resendqs_create();
+       if (rc)
+               return rc;
+
+       rc = lnet_rsp_tracker_create();
+       if (rc)
+               goto clean_queues;
+
+       rc = LNetEQAlloc(0, lnet_mt_event_handler, &the_lnet.ln_mt_eqh);
+       if (rc != 0) {
+               CERROR("Can't allocate monitor thread EQ: %d\n", rc);
+               goto clean_queues;
        }
 
-       /* 'lp' is our best choice of peer */
+       /* Pre monitor thread start processing */
+       rc = lnet_router_pre_mt_start();
+       if (rc)
+               goto free_mem;
 
-       LASSERT(!msg->msg_peertxcredit);
-       LASSERT(!msg->msg_txcredit);
-       LASSERT(msg->msg_txpeer == NULL);
+       sema_init(&the_lnet.ln_mt_signal, 0);
 
-       msg->msg_txpeer = lp;                   /* msg takes my ref on lp */
+       the_lnet.ln_mt_state = LNET_MT_STATE_RUNNING;
+       task = kthread_run(lnet_monitor_thread, NULL, "monitor_thread");
+       if (IS_ERR(task)) {
+               rc = PTR_ERR(task);
+               CERROR("Can't start monitor thread: %d\n", rc);
+               goto clean_thread;
+       }
 
-       rc = lnet_post_send_locked(msg, 0);
-       lnet_net_unlock(cpt);
+       /* post monitor thread start processing */
+       lnet_router_post_mt_start();
 
-       if (rc < 0)
-               return rc;
+       return 0;
 
-       if (rc == LNET_CREDIT_OK)
-               lnet_ni_send(src_ni, msg);
+clean_thread:
+       the_lnet.ln_mt_state = LNET_MT_STATE_STOPPING;
+       /* block until event callback signals exit */
+       down(&the_lnet.ln_mt_signal);
+       /* clean up */
+       lnet_router_cleanup();
+free_mem:
+       the_lnet.ln_mt_state = LNET_MT_STATE_SHUTDOWN;
+       lnet_rsp_tracker_clean();
+       lnet_clean_local_ni_recoveryq();
+       lnet_clean_peer_ni_recoveryq();
+       lnet_clean_resendqs();
+       LNetEQFree(the_lnet.ln_mt_eqh);
+       LNetInvalidateEQHandle(&the_lnet.ln_mt_eqh);
+       return rc;
+clean_queues:
+       lnet_rsp_tracker_clean();
+       lnet_clean_local_ni_recoveryq();
+       lnet_clean_peer_ni_recoveryq();
+       lnet_clean_resendqs();
+       return rc;
+}
+
+void lnet_monitor_thr_stop(void)
+{
+       int rc;
+
+       if (the_lnet.ln_mt_state == LNET_MT_STATE_SHUTDOWN)
+               return;
 
-       return 0; /* rc == LNET_CREDIT_OK or LNET_CREDIT_WAIT */
+       LASSERT(the_lnet.ln_mt_state == LNET_MT_STATE_RUNNING);
+       the_lnet.ln_mt_state = LNET_MT_STATE_STOPPING;
+
+       /* tell the monitor thread that we're shutting down */
+       wake_up(&the_lnet.ln_mt_waitq);
+
+       /* block until monitor thread signals that it's done */
+       down(&the_lnet.ln_mt_signal);
+       LASSERT(the_lnet.ln_mt_state == LNET_MT_STATE_SHUTDOWN);
+
+       /* perform cleanup tasks */
+       lnet_router_cleanup();
+       lnet_rsp_tracker_clean();
+       lnet_clean_local_ni_recoveryq();
+       lnet_clean_peer_ni_recoveryq();
+       lnet_clean_resendqs();
+       rc = LNetEQFree(the_lnet.ln_mt_eqh);
+       LASSERT(rc == 0);
+       return;
 }
 
 void
-lnet_drop_message(lnet_ni_t *ni, int cpt, void *private, unsigned int nob)
+lnet_drop_message(struct lnet_ni *ni, int cpt, void *private, unsigned int nob,
+                 __u32 msg_type)
 {
        lnet_net_lock(cpt);
+       lnet_incr_stats(&ni->ni_stats, msg_type, LNET_STATS_TYPE_DROP);
        the_lnet.ln_counters[cpt]->drop_count++;
        the_lnet.ln_counters[cpt]->drop_length += nob;
        lnet_net_unlock(cpt);
@@ -1415,9 +3599,9 @@ lnet_drop_message(lnet_ni_t *ni, int cpt, void *private, unsigned int nob)
 }
 
 static void
-lnet_recv_put(lnet_ni_t *ni, lnet_msg_t *msg)
+lnet_recv_put(struct lnet_ni *ni, struct lnet_msg *msg)
 {
-       lnet_hdr_t      *hdr = &msg->msg_hdr;
+       struct lnet_hdr *hdr = &msg->msg_hdr;
 
        if (msg->msg_wanted != 0)
                lnet_setpayloadbuffer(msg);
@@ -1434,9 +3618,9 @@ lnet_recv_put(lnet_ni_t *ni, lnet_msg_t *msg)
 }
 
 static int
-lnet_parse_put(lnet_ni_t *ni, lnet_msg_t *msg)
+lnet_parse_put(struct lnet_ni *ni, struct lnet_msg *msg)
 {
-       lnet_hdr_t              *hdr = &msg->msg_hdr;
+       struct lnet_hdr         *hdr = &msg->msg_hdr;
        struct lnet_match_info  info;
        int                     rc;
        bool                    ready_delay;
@@ -1446,15 +3630,17 @@ lnet_parse_put(lnet_ni_t *ni, lnet_msg_t *msg)
        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;
+       /* Primary peer NID. */
+       info.mi_id.nid  = msg->msg_initiator;
        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;
+       info.mi_cpt     = lnet_cpt_of_nid(msg->msg_rxpeer->lpni_nid, ni);
 
-       msg->msg_rx_ready_delay = ni->ni_lnd->lnd_eager_recv == NULL;
+       msg->msg_rx_ready_delay = ni->ni_net->net_lnd->lnd_eager_recv == NULL;
        ready_delay = msg->msg_rx_ready_delay;
 
  again:
@@ -1491,12 +3677,13 @@ lnet_parse_put(lnet_ni_t *ni, lnet_msg_t *msg)
 }
 
 static int
-lnet_parse_get(lnet_ni_t *ni, lnet_msg_t *msg, int rdma_get)
+lnet_parse_get(struct lnet_ni *ni, struct lnet_msg *msg, int rdma_get)
 {
-       struct lnet_match_info  info;
-       lnet_hdr_t              *hdr = &msg->msg_hdr;
-       lnet_handle_wire_t      reply_wmd;
-       int                     rc;
+       struct lnet_match_info info;
+       struct lnet_hdr *hdr = &msg->msg_hdr;
+       struct lnet_process_id source_id;
+       struct lnet_handle_wire reply_wmd;
+       int rc;
 
        /* Convert get fields to host byte order */
        hdr->msg.get.match_bits   = le64_to_cpu(hdr->msg.get.match_bits);
@@ -1504,13 +3691,17 @@ lnet_parse_get(lnet_ni_t *ni, lnet_msg_t *msg, int rdma_get)
        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;
+       source_id.nid = hdr->src_nid;
+       source_id.pid = hdr->src_pid;
+       /* Primary peer NID */
+       info.mi_id.nid  = msg->msg_initiator;
        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;
+       info.mi_cpt     = lnet_cpt_of_nid(msg->msg_rxpeer->lpni_nid, ni);
 
        rc = lnet_ptl_match_md(&info, msg);
        if (rc == LNET_MATCHMD_DROP) {
@@ -1527,7 +3718,7 @@ lnet_parse_get(lnet_ni_t *ni, lnet_msg_t *msg, int rdma_get)
 
        reply_wmd = hdr->msg.get.return_wmd;
 
-       lnet_prep_send(msg, LNET_MSG_REPLY, info.mi_id,
+       lnet_prep_send(msg, LNET_MSG_REPLY, source_id,
                       msg->msg_offset, msg->msg_wanted);
 
        msg->msg_hdr.msg.reply.dst_wmd = reply_wmd;
@@ -1549,22 +3740,22 @@ lnet_parse_get(lnet_ni_t *ni, lnet_msg_t *msg, int rdma_get)
                       libcfs_nid2str(ni->ni_nid),
                       libcfs_id2str(info.mi_id), rc);
 
-               lnet_finalize(ni, msg, rc);
+               lnet_finalize(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;
+lnet_parse_reply(struct lnet_ni *ni, struct lnet_msg *msg)
+{
+       void *private = msg->msg_private;
+       struct lnet_hdr *hdr = &msg->msg_hdr;
+       struct lnet_process_id src = {0};
+       struct lnet_libmd *md;
+       int rlength;
+       int mlength;
+       int cpt;
 
        cpt = lnet_cpt_of_cookie(hdr->msg.reply.dst_wmd.wh_object_cookie);
        lnet_res_lock(cpt);
@@ -1623,12 +3814,12 @@ lnet_parse_reply(lnet_ni_t *ni, lnet_msg_t *msg)
 }
 
 static int
-lnet_parse_ack(lnet_ni_t *ni, lnet_msg_t *msg)
+lnet_parse_ack(struct lnet_ni *ni, struct lnet_msg *msg)
 {
-       lnet_hdr_t       *hdr = &msg->msg_hdr;
-       lnet_process_id_t src = {0};
-       lnet_libmd_t     *md;
-       int                     cpt;
+       struct lnet_hdr *hdr = &msg->msg_hdr;
+       struct lnet_process_id src = {0};
+       struct lnet_libmd *md;
+       int cpt;
 
        src.nid = hdr->src_nid;
        src.pid = hdr->src_pid;
@@ -1678,16 +3869,16 @@ lnet_parse_ack(lnet_ni_t *ni, lnet_msg_t *msg)
  * \retval -ve                 error code
  */
 int
-lnet_parse_forward_locked(lnet_ni_t *ni, lnet_msg_t *msg)
+lnet_parse_forward_locked(struct lnet_ni *ni, struct lnet_msg *msg)
 {
        int     rc = 0;
 
        if (!the_lnet.ln_routing)
                return -ECANCELED;
 
-       if (msg->msg_rxpeer->lp_rtrcredits <= 0 ||
+       if (msg->msg_rxpeer->lpni_rtrcredits <= 0 ||
            lnet_msg2bufpool(msg)->rbp_credits <= 0) {
-               if (ni->ni_lnd->lnd_eager_recv == NULL) {
+               if (ni->ni_net->net_lnd->lnd_eager_recv == NULL) {
                        msg->msg_rx_ready_delay = 1;
                } else {
                        lnet_net_unlock(msg->msg_rx_cpt);
@@ -1702,7 +3893,7 @@ lnet_parse_forward_locked(lnet_ni_t *ni, lnet_msg_t *msg)
 }
 
 int
-lnet_parse_local(lnet_ni_t *ni, lnet_msg_t *msg)
+lnet_parse_local(struct lnet_ni *ni, struct lnet_msg *msg)
 {
        int     rc;
 
@@ -1748,18 +3939,18 @@ lnet_msgtyp2str (int type)
 }
 
 void
-lnet_print_hdr(lnet_hdr_t * hdr)
+lnet_print_hdr(struct lnet_hdr *hdr)
 {
-       lnet_process_id_t src = {0};
-       lnet_process_id_t dst = {0};
+       struct lnet_process_id src = {
+               .nid = hdr->src_nid,
+               .pid = hdr->src_pid,
+       };
+       struct lnet_process_id dst = {
+               .nid = hdr->dest_nid,
+               .pid = hdr->dest_pid,
+       };
        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));
@@ -1810,7 +4001,7 @@ lnet_print_hdr(lnet_hdr_t * hdr)
 }
 
 int
-lnet_parse(lnet_ni_t *ni, lnet_hdr_t *hdr, lnet_nid_t from_nid,
+lnet_parse(struct lnet_ni *ni, struct lnet_hdr *hdr, lnet_nid_t from_nid,
           void *private, int rdma_req)
 {
        int             rc = 0;
@@ -1820,8 +4011,9 @@ lnet_parse(lnet_ni_t *ni, lnet_hdr_t *hdr, lnet_nid_t from_nid,
        lnet_pid_t     dest_pid;
        lnet_nid_t     dest_nid;
        lnet_nid_t     src_nid;
-       __u32          payload_length;
-       __u32          type;
+       struct lnet_peer_ni *lpni;
+       __u32          payload_length;
+       __u32          type;
 
        LASSERT (!in_interrupt ());
 
@@ -1832,7 +4024,14 @@ lnet_parse(lnet_ni_t *ni, lnet_hdr_t *hdr, lnet_nid_t from_nid,
        payload_length = le32_to_cpu(hdr->payload_length);
 
        for_me = (ni->ni_nid == dest_nid);
-       cpt = lnet_cpt_of_nid(from_nid);
+       cpt = lnet_cpt_of_nid(from_nid, ni);
+
+       CDEBUG(D_NET, "TRACE: %s(%s) <- %s : %s - %s\n",
+               libcfs_nid2str(dest_nid),
+               libcfs_nid2str(ni->ni_nid),
+               libcfs_nid2str(src_nid),
+               lnet_msgtyp2str(type),
+               (for_me) ? "for me" : "routed");
 
        switch (type) {
        case LNET_MSG_ACK:
@@ -1936,7 +4135,7 @@ lnet_parse(lnet_ni_t *ni, lnet_hdr_t *hdr, lnet_nid_t from_nid,
        }
 
        if (!list_empty(&the_lnet.ln_drop_rules) &&
-           lnet_drop_rule_match(hdr)) {
+           lnet_drop_rule_match(hdr, NULL)) {
                CDEBUG(D_NET, "%s, src %s, dst %s: Dropping %s to simulate"
                              "silent message loss\n",
                       libcfs_nid2str(from_nid), libcfs_nid2str(src_nid),
@@ -1981,19 +4180,24 @@ lnet_parse(lnet_ni_t *ni, lnet_hdr_t *hdr, lnet_nid_t from_nid,
        }
 
        lnet_net_lock(cpt);
-       rc = lnet_nid2peer_locked(&msg->msg_rxpeer, from_nid, cpt);
-       if (rc != 0) {
+       lpni = lnet_nid2peerni_locked(from_nid, ni->ni_nid, cpt);
+       if (IS_ERR(lpni)) {
                lnet_net_unlock(cpt);
                CERROR("%s, src %s: Dropping %s "
-                      "(error %d looking up sender)\n",
+                      "(error %ld looking up sender)\n",
                       libcfs_nid2str(from_nid), libcfs_nid2str(src_nid),
-                      lnet_msgtyp2str(type), rc);
+                      lnet_msgtyp2str(type), PTR_ERR(lpni));
                lnet_msg_free(msg);
                if (rc == -ESHUTDOWN)
                        /* We are shutting down.  Don't do anything more */
                        return 0;
                goto drop;
        }
+       msg->msg_rxpeer = lpni;
+       msg->msg_rxni = ni;
+       lnet_ni_addref_locked(ni, cpt);
+       /* Multi-Rail: Primary NID of source. */
+       msg->msg_initiator = lnet_peer_primary_nid_locked(src_nid);
 
        if (lnet_isrouter(msg->msg_rxpeer)) {
                lnet_peer_set_alive(msg->msg_rxpeer);
@@ -2040,10 +4244,10 @@ lnet_parse(lnet_ni_t *ni, lnet_hdr_t *hdr, lnet_nid_t from_nid,
 
  free_drop:
        LASSERT(msg->msg_md == NULL);
-       lnet_finalize(ni, msg, rc);
+       lnet_finalize(msg, rc);
 
  drop:
-       lnet_drop_message(ni, cpt, private, payload_length);
+       lnet_drop_message(ni, cpt, private, payload_length, type);
        return 0;
 }
 EXPORT_SYMBOL(lnet_parse);
@@ -2052,10 +4256,10 @@ 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;
+               struct lnet_process_id id = {0};
+               struct lnet_msg *msg;
 
-               msg = list_entry(head->next, lnet_msg_t, msg_list);
+               msg = list_entry(head->next, struct lnet_msg, msg_list);
                list_del(&msg->msg_list);
 
                id.nid = msg->msg_hdr.src_nid;
@@ -2078,15 +4282,17 @@ lnet_drop_delayed_msg_list(struct list_head *head, char *reason)
                 * 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);
+               lnet_drop_message(msg->msg_rxni, msg->msg_rx_cpt,
+                                 msg->msg_private, msg->msg_len,
+                                 msg->msg_type);
+
+               msg->msg_no_resend = true;
                /*
                 * 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);
+               lnet_finalize(msg, -ENOENT);
        }
 }
 
@@ -2094,10 +4300,10 @@ void
 lnet_recv_delayed_msg_list(struct list_head *head)
 {
        while (!list_empty(head)) {
-               lnet_msg_t        *msg;
-               lnet_process_id_t  id;
+               struct lnet_msg *msg;
+               struct lnet_process_id id;
 
-               msg = list_entry(head->next, lnet_msg_t, msg_list);
+               msg = list_entry(head->next, struct lnet_msg, msg_list);
                list_del(&msg->msg_list);
 
                /* md won't disappear under me, since each msg
@@ -2109,6 +4315,7 @@ lnet_recv_delayed_msg_list(struct list_head *head)
                LASSERT(msg->msg_rx_delayed);
                LASSERT(msg->msg_md != NULL);
                LASSERT(msg->msg_rxpeer != NULL);
+               LASSERT(msg->msg_rxni != NULL);
                LASSERT(msg->msg_hdr.type == LNET_MSG_PUT);
 
                CDEBUG(D_NET, "Resuming delayed PUT from %s portal %d "
@@ -2118,10 +4325,47 @@ lnet_recv_delayed_msg_list(struct list_head *head)
                        msg->msg_hdr.msg.put.offset,
                        msg->msg_hdr.payload_length);
 
-               lnet_recv_put(msg->msg_rxpeer->lp_ni, msg);
+               lnet_recv_put(msg->msg_rxni, msg);
        }
 }
 
+static void
+lnet_attach_rsp_tracker(struct lnet_rsp_tracker *rspt, int cpt,
+                       struct lnet_libmd *md, struct lnet_handle_md mdh)
+{
+       s64 timeout_ns;
+
+       /*
+        * MD has a refcount taken by message so it's not going away.
+        * The MD however can be looked up. We need to secure the access
+        * to the md_rspt_ptr by taking the res_lock.
+        * The rspt can be accessed without protection up to when it gets
+        * added to the list.
+        */
+
+       /* debug code */
+       LASSERT(md->md_rspt_ptr == NULL);
+
+       /* we'll use that same event in case we never get a response  */
+       rspt->rspt_mdh = mdh;
+       rspt->rspt_cpt = cpt;
+       timeout_ns = lnet_transaction_timeout * NSEC_PER_SEC;
+       rspt->rspt_deadline = ktime_add_ns(ktime_get(), timeout_ns);
+
+       lnet_res_lock(cpt);
+       /* store the rspt so we can access it when we get the REPLY */
+       md->md_rspt_ptr = rspt;
+       lnet_res_unlock(cpt);
+
+       /*
+        * add to the list of tracked responses. It's added to tail of the
+        * list in order to expire all the older entries first.
+        */
+       lnet_net_lock(cpt);
+       list_add_tail(&rspt->rspt_on_list, the_lnet.ln_mt_rstq[cpt]);
+       lnet_net_unlock(cpt);
+}
+
 /**
  * Initiate an asynchronous PUT operation.
  *
@@ -2164,18 +4408,19 @@ lnet_recv_delayed_msg_list(struct list_head *head)
  * \retval -ENOMEM Memory allocation failure.
  * \retval -ENOENT Invalid MD object.
  *
- * \see lnet_event_t::hdr_data and lnet_event_kind_t.
+ * \see struct lnet_event::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,
+LNetPut(lnet_nid_t self, struct lnet_handle_md mdh, enum lnet_ack_req ack,
+       struct lnet_process_id 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;
+       struct lnet_msg *msg;
+       struct lnet_libmd *md;
+       int cpt;
+       int rc;
+       struct lnet_rsp_tracker *rspt = NULL;
 
        LASSERT(the_lnet.ln_refcount > 0);
 
@@ -2188,13 +4433,24 @@ LNetPut(lnet_nid_t self, lnet_handle_md_t mdh, lnet_ack_req_t ack,
 
        msg = lnet_msg_alloc();
        if (msg == NULL) {
-               CERROR("Dropping PUT to %s: ENOMEM on lnet_msg_t\n",
+               CERROR("Dropping PUT to %s: ENOMEM on struct lnet_msg\n",
                       libcfs_id2str(target));
                return -ENOMEM;
        }
        msg->msg_vmflush = !!memory_pressure_get();
 
        cpt = lnet_cpt_of_cookie(mdh.cookie);
+
+       if (ack == LNET_ACK_REQ) {
+               rspt = lnet_rspt_alloc(cpt);
+               if (!rspt) {
+                       CERROR("Dropping PUT to %s: ENOMEM on response tracker\n",
+                               libcfs_id2str(target));
+                       return -ENOMEM;
+               }
+               INIT_LIST_HEAD(&rspt->rspt_on_list);
+       }
+
        lnet_res_lock(cpt);
 
        md = lnet_handle2md(&mdh);
@@ -2207,6 +4463,7 @@ LNetPut(lnet_nid_t self, lnet_handle_md_t mdh, lnet_ack_req_t ack,
                               md->md_me->me_portal);
                lnet_res_unlock(cpt);
 
+               LIBCFS_FREE(rspt, sizeof(*rspt));
                lnet_msg_free(msg);
                return -ENOENT;
        }
@@ -2239,11 +4496,16 @@ LNetPut(lnet_nid_t self, lnet_handle_md_t mdh, lnet_ack_req_t ack,
 
        lnet_build_msg_event(msg, LNET_EVENT_SEND);
 
+       if (ack == LNET_ACK_REQ)
+               lnet_attach_rsp_tracker(rspt, cpt, md, mdh);
+
        rc = lnet_send(self, msg, LNET_NID_ANY);
        if (rc != 0) {
                CNETERR("Error sending PUT to %s: %d\n",
                        libcfs_id2str(target), rc);
-               lnet_finalize(NULL, msg, rc);
+               msg->msg_no_resend = true;
+               lnet_detach_rsp_tracker(msg->msg_md, cpt);
+               lnet_finalize(msg, rc);
        }
 
        /* completion will be signalled by an event */
@@ -2251,20 +4513,21 @@ LNetPut(lnet_nid_t self, lnet_handle_md_t mdh, lnet_ack_req_t ack,
 }
 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 *
+lnet_create_reply_msg(struct lnet_ni *ni, struct lnet_msg *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;
+       struct lnet_msg *msg = lnet_msg_alloc();
+       struct lnet_libmd *getmd = getmsg->msg_md;
+       struct lnet_process_id peer_id = getmsg->msg_target;
+       int cpt;
 
        LASSERT(!getmsg->msg_target_is_router);
        LASSERT(!getmsg->msg_routing);
@@ -2294,6 +4557,7 @@ lnet_create_reply_msg (lnet_ni_t *ni, lnet_msg_t *getmsg)
               libcfs_nid2str(ni->ni_nid), libcfs_id2str(peer_id), getmd);
 
        /* setup information for lnet_build_msg_event */
+       msg->msg_initiator = getmsg->msg_txpeer->lpni_peer_net->lpn_peer->lp_primary_nid;
        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;
@@ -2303,7 +4567,7 @@ lnet_create_reply_msg (lnet_ni_t *ni, lnet_msg_t *getmsg)
        lnet_msg_attach_md(msg, getmd, getmd->md_offset, getmd->md_length);
        lnet_res_unlock(cpt);
 
-       cpt = lnet_cpt_of_nid(peer_id.nid);
+       cpt = lnet_cpt_of_nid(peer_id.nid, ni);
 
        lnet_net_lock(cpt);
        lnet_msg_commit(msg, cpt);
@@ -2314,9 +4578,10 @@ lnet_create_reply_msg (lnet_ni_t *ni, lnet_msg_t *getmsg)
        return msg;
 
  drop:
-       cpt = lnet_cpt_of_nid(peer_id.nid);
+       cpt = lnet_cpt_of_nid(peer_id.nid, ni);
 
        lnet_net_lock(cpt);
+       lnet_incr_stats(&ni->ni_stats, LNET_MSG_GET, LNET_STATS_TYPE_DROP);
        the_lnet.ln_counters[cpt]->drop_count++;
        the_lnet.ln_counters[cpt]->drop_length += getmd->md_length;
        lnet_net_unlock(cpt);
@@ -2329,7 +4594,8 @@ lnet_create_reply_msg (lnet_ni_t *ni, lnet_msg_t *getmsg)
 EXPORT_SYMBOL(lnet_create_reply_msg);
 
 void
-lnet_set_reply_msg_len(lnet_ni_t *ni, lnet_msg_t *reply, unsigned int len)
+lnet_set_reply_msg_len(struct lnet_ni *ni, struct lnet_msg *reply,
+                      unsigned int len)
 {
        /* Set the REPLY length, now the RDMA that elides the REPLY message has
         * completed and I know it. */
@@ -2366,14 +4632,15 @@ EXPORT_SYMBOL(lnet_set_reply_msg_len);
  * \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)
+LNetGet(lnet_nid_t self, struct lnet_handle_md mdh,
+       struct lnet_process_id target, unsigned int portal,
+       __u64 match_bits, unsigned int offset, bool recovery)
 {
-       struct lnet_msg         *msg;
-       struct lnet_libmd       *md;
-       int                     cpt;
-       int                     rc;
+       struct lnet_msg *msg;
+       struct lnet_libmd *md;
+       struct lnet_rsp_tracker *rspt;
+       int cpt;
+       int rc;
 
        LASSERT(the_lnet.ln_refcount > 0);
 
@@ -2386,13 +4653,24 @@ LNetGet(lnet_nid_t self, lnet_handle_md_t mdh,
        }
 
        msg = lnet_msg_alloc();
-       if (msg == NULL) {
-               CERROR("Dropping GET to %s: ENOMEM on lnet_msg_t\n",
+       if (!msg) {
+               CERROR("Dropping GET to %s: ENOMEM on struct lnet_msg\n",
                       libcfs_id2str(target));
                return -ENOMEM;
        }
 
        cpt = lnet_cpt_of_cookie(mdh.cookie);
+
+       rspt = lnet_rspt_alloc(cpt);
+       if (!rspt) {
+               CERROR("Dropping GET to %s: ENOMEM on response tracker\n",
+                      libcfs_id2str(target));
+               return -ENOMEM;
+       }
+       INIT_LIST_HEAD(&rspt->rspt_on_list);
+
+       msg->msg_recovery = recovery;
+
        lnet_res_lock(cpt);
 
        md = lnet_handle2md(&mdh);
@@ -2407,6 +4685,7 @@ LNetGet(lnet_nid_t self, lnet_handle_md_t mdh,
                lnet_res_unlock(cpt);
 
                lnet_msg_free(msg);
+               LIBCFS_FREE(rspt, sizeof(*rspt));
                return -ENOENT;
        }
 
@@ -2431,11 +4710,15 @@ LNetGet(lnet_nid_t self, lnet_handle_md_t mdh,
 
        lnet_build_msg_event(msg, LNET_EVENT_SEND);
 
+       lnet_attach_rsp_tracker(rspt, cpt, md, mdh);
+
        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);
+               msg->msg_no_resend = true;
+               lnet_detach_rsp_tracker(msg->msg_md, cpt);
+               lnet_finalize(msg, rc);
        }
 
        /* completion will be signalled by an event */
@@ -2461,8 +4744,8 @@ int
 LNetDist(lnet_nid_t dstnid, lnet_nid_t *srcnidp, __u32 *orderp)
 {
        struct list_head        *e;
-       struct lnet_ni          *ni;
-       lnet_remotenet_t        *rnet;
+       struct lnet_ni *ni = NULL;
+       struct lnet_remotenet *rnet;
        __u32                   dstnet = LNET_NIDNET(dstnid);
        int                     hops;
        int                     cpt;
@@ -2478,9 +4761,7 @@ LNetDist(lnet_nid_t dstnid, lnet_nid_t *srcnidp, __u32 *orderp)
 
        cpt = lnet_net_lock_current();
 
-       list_for_each(e, &the_lnet.ln_nis) {
-               ni = list_entry(e, lnet_ni_t, ni_list);
-
+       while ((ni = lnet_get_next_ni_locked(NULL, ni))) {
                if (ni->ni_nid == dstnid) {
                        if (srcnidp != NULL)
                                *srcnidp = dstnid;
@@ -2516,11 +4797,11 @@ LNetDist(lnet_nid_t dstnid, lnet_nid_t *srcnidp, __u32 *orderp)
 
        rn_list = lnet_net2rnethash(dstnet);
        list_for_each(e, rn_list) {
-               rnet = list_entry(e, lnet_remotenet_t, lrn_list);
+               rnet = list_entry(e, struct lnet_remotenet, lrn_list);
 
                if (rnet->lrn_net == dstnet) {
-                       lnet_route_t *route;
-                       lnet_route_t *shortest = NULL;
+                       struct lnet_route *route;
+                       struct lnet_route *shortest = NULL;
                        __u32 shortest_hops = LNET_UNDEFINED_HOPS;
                        __u32 route_hops;
 
@@ -2540,8 +4821,12 @@ LNetDist(lnet_nid_t dstnid, lnet_nid_t *srcnidp, __u32 *orderp)
 
                        LASSERT(shortest != NULL);
                        hops = shortest_hops;
-                       if (srcnidp != NULL)
-                               *srcnidp = shortest->lr_gateway->lp_ni->ni_nid;
+                       if (srcnidp != NULL) {
+                               ni = lnet_get_next_ni_locked(
+                                       shortest->lr_gateway->lpni_net,
+                                       NULL);
+                               *srcnidp = ni->ni_nid;
+                       }
                        if (orderp != NULL)
                                *orderp = order;
                        lnet_net_unlock(cpt);