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LU-13362 lnet: Disc reply race with finalize and routed recv
[fs/lustre-release.git] / lnet / lnet / lib-move.c
index 9f1a580..d74cfcc 100644 (file)
@@ -63,6 +63,12 @@ struct lnet_send_data {
        __u32 sd_send_case;
 };
 
+static inline bool
+lnet_msg_is_response(struct lnet_msg *msg)
+{
+       return msg->msg_type == LNET_MSG_ACK || msg->msg_type == LNET_MSG_REPLY;
+}
+
 static inline struct lnet_comm_count *
 get_stats_counts(struct lnet_element_stats *stats,
                 enum lnet_stats_type stats_type)
@@ -165,7 +171,7 @@ lnet_fail_nid(lnet_nid_t nid, unsigned int threshold)
        struct lnet_test_peer *tp;
        struct list_head *el;
        struct list_head *next;
-       struct list_head  cull;
+       LIST_HEAD(cull);
 
        /* NB: use lnet_net_lock(0) to serialize operations on test peers */
        if (threshold != 0) {
@@ -183,9 +189,6 @@ lnet_fail_nid(lnet_nid_t nid, unsigned int threshold)
                return 0;
        }
 
-       /* removing entries */
-       INIT_LIST_HEAD(&cull);
-
        lnet_net_lock(0);
 
        list_for_each_safe(el, next, &the_lnet.ln_test_peers) {
@@ -215,10 +218,8 @@ fail_peer (lnet_nid_t nid, int outgoing)
        struct lnet_test_peer *tp;
        struct list_head *el;
        struct list_head *next;
-       struct list_head  cull;
-       int               fail = 0;
-
-       INIT_LIST_HEAD(&cull);
+       LIST_HEAD(cull);
+       int fail = 0;
 
        /* NB: use lnet_net_lock(0) to serialize operations on test peers */
        lnet_net_lock(0);
@@ -284,7 +285,7 @@ lnet_copy_iov2iov(unsigned int ndiov, struct kvec *diov, unsigned int doffset,
                  unsigned int nob)
 {
        /* NB diov, siov are READ-ONLY */
-       unsigned int  this_nob;
+       unsigned int this_nob;
 
        if (nob == 0)
                return;
@@ -310,9 +311,9 @@ lnet_copy_iov2iov(unsigned int ndiov, struct kvec *diov, unsigned int doffset,
        do {
                LASSERT(ndiov > 0);
                LASSERT(nsiov > 0);
-               this_nob = MIN(diov->iov_len - doffset,
-                              siov->iov_len - soffset);
-               this_nob = MIN(this_nob, nob);
+               this_nob = min3((unsigned int)diov->iov_len - doffset,
+                               (unsigned int)siov->iov_len - soffset,
+                               nob);
 
                memcpy((char *)diov->iov_base + doffset,
                       (char *)siov->iov_base + soffset, this_nob);
@@ -432,9 +433,9 @@ lnet_copy_kiov2kiov(unsigned int ndiov, lnet_kiov_t *diov, unsigned int doffset,
        do {
                LASSERT(ndiov > 0);
                LASSERT(nsiov > 0);
-               this_nob = MIN(diov->kiov_len - doffset,
-                              siov->kiov_len - soffset);
-               this_nob = MIN(this_nob, nob);
+               this_nob = min3(diov->kiov_len - doffset,
+                               siov->kiov_len - soffset,
+                               nob);
 
                if (daddr == NULL)
                        daddr = ((char *)kmap(diov->kiov_page)) +
@@ -513,9 +514,9 @@ lnet_copy_kiov2iov (unsigned int niov, struct kvec *iov, unsigned int iovoffset,
        do {
                LASSERT(niov > 0);
                LASSERT(nkiov > 0);
-               this_nob = MIN(iov->iov_len - iovoffset,
-                              kiov->kiov_len - kiovoffset);
-               this_nob = MIN(this_nob, nob);
+               this_nob = min3((unsigned int)iov->iov_len - iovoffset,
+                               (unsigned int)kiov->kiov_len - kiovoffset,
+                               nob);
 
                if (addr == NULL)
                        addr = ((char *)kmap(kiov->kiov_page)) +
@@ -583,9 +584,9 @@ lnet_copy_iov2kiov(unsigned int nkiov, lnet_kiov_t *kiov, unsigned int kiovoffse
        do {
                LASSERT(nkiov > 0);
                LASSERT(niov > 0);
-               this_nob = MIN(kiov->kiov_len - kiovoffset,
-                              iov->iov_len - iovoffset);
-               this_nob = MIN(this_nob, nob);
+               this_nob = min3((unsigned int)kiov->kiov_len - kiovoffset,
+                               (unsigned int)iov->iov_len - iovoffset,
+                               nob);
 
                if (addr == NULL)
                        addr = ((char *)kmap(kiov->kiov_page)) +
@@ -832,8 +833,7 @@ lnet_peer_alive_locked(struct lnet_ni *ni, struct lnet_peer_ni *lpni,
                return 1;
 
        /* always send any responses */
-       if (msg->msg_type == LNET_MSG_ACK ||
-           msg->msg_type == LNET_MSG_REPLY)
+       if (lnet_msg_is_response(msg))
                return 1;
 
        if (!lnet_is_peer_deadline_passed(lpni, now))
@@ -1012,8 +1012,6 @@ lnet_post_routed_recv_locked(struct lnet_msg *msg, int do_recv)
        if (!msg->msg_peerrtrcredit) {
                /* lpni_lock protects the credit manipulation */
                spin_lock(&lpni->lpni_lock);
-               /* lp_lock protects the lp_rtrq */
-               spin_lock(&lp->lp_lock);
 
                msg->msg_peerrtrcredit = 1;
                lpni->lpni_rtrcredits--;
@@ -1021,15 +1019,16 @@ lnet_post_routed_recv_locked(struct lnet_msg *msg, int do_recv)
                        lpni->lpni_minrtrcredits = lpni->lpni_rtrcredits;
 
                if (lpni->lpni_rtrcredits < 0) {
+                       spin_unlock(&lpni->lpni_lock);
                        /* must have checked eager_recv before here */
                        LASSERT(msg->msg_rx_ready_delay);
                        msg->msg_rx_delayed = 1;
+                       /* lp_lock protects the lp_rtrq */
+                       spin_lock(&lp->lp_lock);
                        list_add_tail(&msg->msg_list, &lp->lp_rtrq);
                        spin_unlock(&lp->lp_lock);
-                       spin_unlock(&lpni->lpni_lock);
                        return LNET_CREDIT_WAIT;
                }
-               spin_unlock(&lp->lp_lock);
                spin_unlock(&lpni->lpni_lock);
        }
 
@@ -1256,24 +1255,22 @@ routing_off:
                LASSERT(rxpeerni->lpni_peer_net);
                LASSERT(rxpeerni->lpni_peer_net->lpn_peer);
 
-               lp = rxpeerni->lpni_peer_net->lpn_peer;
-
                /* give back peer router credits */
                msg->msg_peerrtrcredit = 0;
 
                spin_lock(&rxpeerni->lpni_lock);
-               spin_lock(&lp->lp_lock);
-
                rxpeerni->lpni_rtrcredits++;
+               spin_unlock(&rxpeerni->lpni_lock);
+
+               lp = rxpeerni->lpni_peer_net->lpn_peer;
+               spin_lock(&lp->lp_lock);
 
                /* drop all messages which are queued to be routed on that
                 * peer. */
                if (!the_lnet.ln_routing) {
-                       struct list_head drop;
-                       INIT_LIST_HEAD(&drop);
+                       LIST_HEAD(drop);
                        list_splice_init(&lp->lp_rtrq, &drop);
                        spin_unlock(&lp->lp_lock);
-                       spin_unlock(&rxpeerni->lpni_lock);
                        lnet_drop_routed_msgs_locked(&drop, msg->msg_rx_cpt);
                } else if (!list_empty(&lp->lp_rtrq)) {
                        int msg2_cpt;
@@ -1283,7 +1280,6 @@ routing_off:
                        list_del(&msg2->msg_list);
                        msg2_cpt = msg2->msg_rx_cpt;
                        spin_unlock(&lp->lp_lock);
-                       spin_unlock(&rxpeerni->lpni_lock);
                        /*
                         * messages on the lp_rtrq can be from any NID in
                         * the peer, which means they might have different
@@ -1301,7 +1297,6 @@ routing_off:
                        }
                } else {
                        spin_unlock(&lp->lp_lock);
-                       spin_unlock(&rxpeerni->lpni_lock);
                }
        }
        if (rxni != NULL) {
@@ -1315,7 +1310,7 @@ routing_off:
 }
 
 static int
-lnet_compare_peers(struct lnet_peer_ni *p1, struct lnet_peer_ni *p2)
+lnet_compare_gw_lpnis(struct lnet_peer_ni *p1, struct lnet_peer_ni *p2)
 {
        if (p1->lpni_txqnob < p2->lpni_txqnob)
                return 1;
@@ -1432,8 +1427,8 @@ lnet_select_peer_ni(struct lnet_ni *best_ni, lnet_nid_t dst_nid,
  * 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)
+lnet_find_best_lpni_on_net(struct lnet_ni *lni, lnet_nid_t dst_nid,
+                          struct lnet_peer *peer, __u32 net_id)
 {
        struct lnet_peer_net *peer_net;
 
@@ -1443,115 +1438,100 @@ lnet_find_best_lpni_on_net(struct lnet_send_data *sd, struct lnet_peer *peer,
         */
        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->sd_best_ni, sd->sd_dst_nid,
-                                  peer, peer_net);
+       return lnet_select_peer_ni(lni, dst_nid, peer, peer_net);
 }
 
+/* Compare route priorities and hop counts */
 static int
-lnet_compare_routes(struct lnet_route *r1, struct lnet_route *r2,
-                   struct lnet_peer_ni **best_lpni)
+lnet_compare_routes(struct lnet_route *r1, struct lnet_route *r2)
 {
        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 lnet_peer *lp1 = r1->lr_gateway;
-       struct lnet_peer *lp2 = r2->lr_gateway;
-       struct lnet_peer_ni *lpni1;
-       struct lnet_peer_ni *lpni2;
-       struct lnet_send_data sd;
-       int rc;
 
-       sd.sd_best_ni = NULL;
-       sd.sd_dst_nid = LNET_NID_ANY;
-       lpni1 = lnet_find_best_lpni_on_net(&sd, lp1, r1->lr_lnet);
-       lpni2 = lnet_find_best_lpni_on_net(&sd, lp2, r2->lr_lnet);
-       LASSERT(lpni1 && lpni2);
-
-       if (r1->lr_priority < r2->lr_priority) {
-               *best_lpni = lpni1;
+       if (r1->lr_priority < r2->lr_priority)
                return 1;
-       }
 
-       if (r1->lr_priority > r2->lr_priority) {
-               *best_lpni = lpni2;
+       if (r1->lr_priority > r2->lr_priority)
                return -1;
-       }
 
-       if (r1_hops < r2_hops) {
-               *best_lpni = lpni1;
+       if (r1_hops < r2_hops)
                return 1;
-       }
 
-       if (r1_hops > r2_hops) {
-               *best_lpni = lpni2;
+       if (r1_hops > r2_hops)
                return -1;
-       }
-
-       rc = lnet_compare_peers(lpni1, lpni2);
-       if (rc == 1) {
-               *best_lpni = lpni1;
-               return rc;
-       } else if (rc == -1) {
-               *best_lpni = lpni2;
-               return rc;
-       }
-
-       if (r1->lr_seq - r2->lr_seq <= 0) {
-               *best_lpni = lpni1;
-               return 1;
-       }
 
-       *best_lpni = lpni2;
-       return -1;
+       return 0;
 }
 
 static struct lnet_route *
-lnet_find_route_locked(struct lnet_net *net, __u32 remote_net,
+lnet_find_route_locked(struct lnet_remotenet *rnet, __u32 src_net,
                       struct lnet_route **prev_route,
                       struct lnet_peer_ni **gwni)
 {
-       struct lnet_peer_ni *best_gw_ni = NULL;
+       struct lnet_peer_ni *lpni, *best_gw_ni = NULL;
        struct lnet_route *best_route;
        struct lnet_route *last_route;
-       struct lnet_remotenet *rnet;
-       struct lnet_peer *lp_best;
        struct lnet_route *route;
-       struct lnet_peer *lp;
        int rc;
 
-       rnet = lnet_find_rnet_locked(remote_net);
-       if (rnet == NULL)
-               return NULL;
-
-       lp_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 (lp_best == NULL) {
-                       best_route = last_route = route;
-                       lp_best = lp;
+               /*
+                * Restrict the selection of the router NI on the src_net
+                * provided. If the src_net is LNET_NID_ANY, then select
+                * the best interface available.
+                */
+               if (!best_route) {
+                       lpni = lnet_find_best_lpni_on_net(NULL, LNET_NID_ANY,
+                                                         route->lr_gateway,
+                                                         src_net);
+                       if (lpni) {
+                               best_route = last_route = route;
+                               best_gw_ni = lpni;
+                       } else
+                               CERROR("Gateway %s does not have a peer NI on net %s\n",
+                                      libcfs_nid2str(route->lr_gateway->lp_primary_nid),
+                                      libcfs_net2str(src_net));
+
+                       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, &best_gw_ni);
-               if (rc < 0)
+               rc = lnet_compare_routes(route, best_route);
+               if (rc == -1)
+                       continue;
+
+               lpni = lnet_find_best_lpni_on_net(NULL, LNET_NID_ANY,
+                                                 route->lr_gateway,
+                                                 src_net);
+               if (!lpni) {
+                       CERROR("Gateway %s does not have a peer NI on net %s\n",
+                              libcfs_nid2str(route->lr_gateway->lp_primary_nid),
+                              libcfs_net2str(src_net));
+                       continue;
+               }
+
+               if (rc == 1) {
+                       best_route = route;
+                       best_gw_ni = lpni;
+                       continue;
+               }
+
+               rc = lnet_compare_gw_lpnis(lpni, best_gw_ni);
+               if (rc == -1)
                        continue;
 
-               best_route = route;
-               lp_best = lp;
+               if (rc == 1 || route->lr_seq <= best_route->lr_seq) {
+                       best_route = route;
+                       best_gw_ni = lpni;
+                       continue;
+               }
        }
 
        *prev_route = last_route;
@@ -1855,17 +1835,14 @@ lnet_handle_send(struct lnet_send_data *sd)
 }
 
 static inline void
-lnet_set_non_mr_pref_nid(struct lnet_send_data *sd)
+lnet_set_non_mr_pref_nid(struct lnet_peer_ni *lpni, struct lnet_ni *lni,
+                        struct lnet_msg *msg)
 {
-       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) {
+       if (!lnet_msg_is_response(msg) && 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);
+                      libcfs_nid2str(lni->ni_nid),
+                      libcfs_nid2str(lpni->lpni_nid));
+               lnet_peer_ni_set_non_mr_pref_nid(lpni, lni->ni_nid);
        }
 }
 
@@ -1890,10 +1867,7 @@ lnet_handle_spec_local_nmr_dst(struct lnet_send_data *sd)
                return -EINVAL;
        }
 
-       /*
-        * the preferred NID will only be set for NMR peers
-        */
-       lnet_set_non_mr_pref_nid(sd);
+       lnet_set_non_mr_pref_nid(sd->sd_best_lpni, sd->sd_best_ni, sd->sd_msg);
 
        return lnet_handle_send(sd);
 }
@@ -1965,12 +1939,10 @@ lnet_find_best_ni_on_spec_net(struct lnet_ni *cur_best_ni,
 }
 
 static int
-lnet_initiate_peer_discovery(struct lnet_peer_ni *lpni,
-                            struct lnet_msg *msg, lnet_nid_t rtr_nid,
+lnet_initiate_peer_discovery(struct lnet_peer_ni *lpni, struct lnet_msg *msg,
                             int cpt)
 {
        struct lnet_peer *peer;
-       lnet_nid_t primary_nid;
        int rc;
 
        lnet_peer_ni_addref_locked(lpni);
@@ -2001,17 +1973,15 @@ lnet_initiate_peer_discovery(struct lnet_peer_ni *lpni,
                return 0;
        }
        /* queue message and return */
-       msg->msg_rtr_nid_param = rtr_nid;
        msg->msg_sending = 0;
        msg->msg_txpeer = NULL;
        list_add_tail(&msg->msg_list, &peer->lp_dc_pendq);
-       primary_nid = peer->lp_primary_nid;
        spin_unlock(&peer->lp_lock);
 
        lnet_peer_ni_decref_locked(lpni);
 
        CDEBUG(D_NET, "msg %p delayed. %s pending discovery\n",
-               msg, libcfs_nid2str(primary_nid));
+              msg, libcfs_nid2str(peer->lp_primary_nid));
 
        return LNET_DC_WAIT;
 }
@@ -2028,7 +1998,7 @@ lnet_handle_find_routed_path(struct lnet_send_data *sd,
        struct lnet_peer *lp;
        struct lnet_peer_net *lpn;
        struct lnet_peer_net *best_lpn = NULL;
-       struct lnet_remotenet *rnet;
+       struct lnet_remotenet *rnet, *best_rnet = NULL;
        struct lnet_route *best_route = NULL;
        struct lnet_route *last_route = NULL;
        struct lnet_peer_ni *lpni = NULL;
@@ -2063,13 +2033,16 @@ lnet_handle_find_routed_path(struct lnet_send_data *sd,
                        if (!rnet)
                                continue;
 
-                       if (!best_lpn)
+                       if (!best_lpn) {
                                best_lpn = lpn;
+                               best_rnet = rnet;
+                       }
 
                        if (best_lpn->lpn_seq <= lpn->lpn_seq)
                                continue;
 
                        best_lpn = lpn;
+                       best_rnet = rnet;
                }
 
                if (!best_lpn) {
@@ -2078,14 +2051,18 @@ lnet_handle_find_routed_path(struct lnet_send_data *sd,
                        return -EHOSTUNREACH;
                }
 
-               sd->sd_best_lpni = lnet_find_best_lpni_on_net(sd, lp, best_lpn->lpn_net_id);
+               sd->sd_best_lpni = lnet_find_best_lpni_on_net(sd->sd_best_ni,
+                                                             sd->sd_dst_nid,
+                                                             lp,
+                                                             best_lpn->lpn_net_id);
                if (!sd->sd_best_lpni) {
                        CERROR("peer %s down\n",
                               libcfs_nid2str(sd->sd_dst_nid));
                        return -EHOSTUNREACH;
                }
 
-               best_route = lnet_find_route_locked(NULL, best_lpn->lpn_net_id,
+               best_route = lnet_find_route_locked(best_rnet,
+                                                   LNET_NIDNET(src_nid),
                                                    &last_route, &gwni);
                if (!best_route) {
                        CERROR("no route to %s from %s\n",
@@ -2113,8 +2090,7 @@ lnet_handle_find_routed_path(struct lnet_send_data *sd,
         * completed
         */
        sd->sd_msg->msg_src_nid_param = sd->sd_src_nid;
-       rc = lnet_initiate_peer_discovery(gwni, sd->sd_msg, sd->sd_rtr_nid,
-                                         sd->sd_cpt);
+       rc = lnet_initiate_peer_discovery(gwni, sd->sd_msg, sd->sd_cpt);
        if (rc)
                return rc;
 
@@ -2187,10 +2163,11 @@ lnet_handle_spec_router_dst(struct lnet_send_data *sd)
 
        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);
+                * since the final destination is non-MR let's set its preferred
+                * NID before we send
+                */
+               lnet_set_non_mr_pref_nid(sd->sd_best_lpni, sd->sd_best_ni,
+                                        sd->sd_msg);
 
        /*
         * We're going to send to the gw found so let's set its
@@ -2208,6 +2185,7 @@ 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;
+       int lpn_healthv = 0;
 
        /*
         * The peer can have multiple interfaces, some of them can be on
@@ -2224,8 +2202,15 @@ lnet_find_best_ni_on_local_net(struct lnet_peer *peer, int md_cpt,
                 */
                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);
+
+               /* always select the lpn with the best health */
+               if (lpn_healthv <= peer_net->lpn_healthv)
+                       lpn_healthv = peer_net->lpn_healthv;
+               else
+                       continue;
+
+               best_ni = lnet_find_best_ni_on_spec_net(best_ni, peer, peer_net,
+                                                       md_cpt, false);
 
                /*
                 * if this is a discovery message and lp_disc_net_id is
@@ -2244,14 +2229,11 @@ lnet_find_best_ni_on_local_net(struct lnet_peer *peer, int md_cpt,
 }
 
 static struct lnet_ni *
-lnet_find_existing_preferred_best_ni(struct lnet_send_data *sd)
+lnet_find_existing_preferred_best_ni(struct lnet_peer_ni *lpni, int cpt)
 {
        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;
+       struct lnet_peer_net *peer_net = lpni->lpni_peer_net;
+       struct lnet_peer_ni *lpni_entry;
 
        /*
         * We must use a consistent source address when sending to a
@@ -2263,18 +2245,13 @@ lnet_find_existing_preferred_best_ni(struct lnet_send_data *sd)
         * 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)
+       LASSERT(peer_net);
+       list_for_each_entry(lpni_entry, &peer_net->lpn_peer_nis,
+                           lpni_peer_nis) {
+               if (lpni_entry->lpni_pref_nnids == 0)
                        continue;
-               LASSERT(lpni->lpni_pref_nnids == 1);
-               best_ni = lnet_nid2ni_locked(
-                               lpni->lpni_pref.nid, cpt);
+               LASSERT(lpni_entry->lpni_pref_nnids == 1);
+               best_ni = lnet_nid2ni_locked(lpni_entry->lpni_pref.nid, cpt);
                break;
        }
 
@@ -2299,7 +2276,8 @@ lnet_select_preferred_best_ni(struct lnet_send_data *sd)
         * particular network.
         */
 
-       best_ni = lnet_find_existing_preferred_best_ni(sd);
+       best_ni = lnet_find_existing_preferred_best_ni(sd->sd_best_lpni,
+                                                      sd->sd_cpt);
 
        /* if best_ni is still not set just pick one */
        if (!best_ni) {
@@ -2319,7 +2297,7 @@ lnet_select_preferred_best_ni(struct lnet_send_data *sd)
        sd->sd_best_ni = best_ni;
 
        /* Set preferred NI if necessary. */
-       lnet_set_non_mr_pref_nid(sd);
+       lnet_set_non_mr_pref_nid(sd->sd_best_lpni, sd->sd_best_ni, sd->sd_msg);
 
        return 0;
 }
@@ -2407,7 +2385,8 @@ lnet_handle_any_mr_dsta(struct lnet_send_data *sd)
                                        lnet_msg_discovery(sd->sd_msg));
        if (sd->sd_best_ni) {
                sd->sd_best_lpni =
-                 lnet_find_best_lpni_on_net(sd, sd->sd_peer,
+                 lnet_find_best_lpni_on_net(sd->sd_best_ni, sd->sd_dst_nid,
+                                            sd->sd_peer,
                                             sd->sd_best_ni->ni_net->net_id);
 
                /*
@@ -2551,9 +2530,10 @@ lnet_handle_any_router_nmr_dst(struct lnet_send_data *sd)
        struct lnet_peer *gw_peer = NULL;
 
        /*
-        * Let's set if we have a preferred NI to talk to this NMR peer
+        * Let's see if we have a preferred NI to talk to this NMR peer
         */
-       sd->sd_best_ni = lnet_find_existing_preferred_best_ni(sd);
+       sd->sd_best_ni = lnet_find_existing_preferred_best_ni(sd->sd_best_lpni,
+                                                             sd->sd_cpt);
 
        /*
         * find the router and that'll find the best NI if we didn't find
@@ -2568,7 +2548,7 @@ lnet_handle_any_router_nmr_dst(struct lnet_send_data *sd)
         * set the best_ni we've chosen as the preferred one for
         * this peer
         */
-       lnet_set_non_mr_pref_nid(sd);
+       lnet_set_non_mr_pref_nid(sd->sd_best_lpni, sd->sd_best_ni, sd->sd_msg);
 
        /* we'll be sending to the gw */
        sd->sd_best_lpni = gw_lpni;
@@ -2651,20 +2631,13 @@ lnet_select_pathway(lnet_nid_t src_nid, lnet_nid_t dst_nid,
 again:
 
        /*
-        * If we're sending to ourselves then there is no need to go through
-        * any selection. We can shortcut the entire process and send over
-        * lolnd.
-        *
-        * However, we make two exceptions to this rule:
-        * 1. If the src_nid is specified then our API defines that we must send
-        *    via that interface.
-        * 2. Recovery messages must be sent to the lnet_ni that is being
-        *    recovered.
+        * 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
         */
        send_data.sd_msg = msg;
        send_data.sd_cpt = cpt;
-       if (src_nid == LNET_NID_ANY && !msg->msg_recovery &&
-           lnet_nid2ni_locked(dst_nid, cpt)) {
+       if (LNET_NETTYP(LNET_NIDNET(dst_nid)) == LOLND) {
                rc = lnet_handle_lo_send(&send_data);
                lnet_net_unlock(cpt);
                return rc;
@@ -2682,20 +2655,22 @@ again:
        }
 
        /*
-        * Cache the original src_nid. If we need to resend the message
-        * then we'll need to know whether the src_nid was originally
+        * Cache the original src_nid and rtr_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.
+        * continuing the same sequence of messages. Similarly, rtr_nid will
+        * affect our choice of next hop.
         */
        msg->msg_src_nid_param = src_nid;
+       msg->msg_rtr_nid_param = rtr_nid;
 
        /*
         * If necessary, perform discovery on the peer that owns this peer_ni.
         * Note, this can result in the ownership of this peer_ni changing
         * to another peer object.
         */
-       rc = lnet_initiate_peer_discovery(lpni, msg, rtr_nid, cpt);
+       rc = lnet_initiate_peer_discovery(lpni, msg, cpt);
        if (rc) {
                lnet_peer_ni_decref_locked(lpni);
                lnet_net_unlock(cpt);
@@ -2719,17 +2694,21 @@ again:
                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.
+        * Deal with the peer as NMR in the following cases:
+        * 1. the peer is NMR
+        * 2. We're trying to recover a specific peer NI
+        * 3. I'm a router sending to the final destination
+        *    In this case the source of the message would've
+        *    already selected the final destination so my job
+        *    is to honor the selection.
         */
-       if (!lnet_peer_is_multi_rail(peer) || msg->msg_recovery)
+       if (!lnet_peer_is_multi_rail(peer) || msg->msg_recovery ||
+           (msg->msg_routing && (send_case & LOCAL_DST)))
                send_case |= NMR_DST;
        else
                send_case |= MR_DST;
 
-       if (msg->msg_type == LNET_MSG_REPLY ||
-           msg->msg_type == LNET_MSG_ACK)
+       if (lnet_msg_is_response(msg))
                send_case |= SND_RESP;
 
        /* assign parameters to the send_data */
@@ -2873,7 +2852,6 @@ static void
 lnet_finalize_expired_responses(void)
 {
        struct lnet_libmd *md;
-       struct list_head local_queue;
        struct lnet_rsp_tracker *rspt, *tmp;
        ktime_t now;
        int i;
@@ -2882,7 +2860,7 @@ lnet_finalize_expired_responses(void)
                return;
 
        cfs_cpt_for_each(i, lnet_cpt_table()) {
-               INIT_LIST_HEAD(&local_queue);
+               LIST_HEAD(local_queue);
 
                lnet_net_lock(i);
                if (!the_lnet.ln_mt_rstq[i]) {
@@ -3025,40 +3003,19 @@ lnet_resend_pending_msgs_locked(struct list_head *resendq, int cpt)
                        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 try# %d\n",
-                              libcfs_nid2str(src_nid),
+                              libcfs_nid2str(msg->msg_src_nid_param),
                               libcfs_id2str(msg->msg_target),
                               lnet_msgtyp2str(msg->msg_type),
                               msg->msg_recovery,
                               msg->msg_retry_count);
-                       rc = lnet_send(src_nid, msg, LNET_NID_ANY);
+                       rc = lnet_send(msg->msg_src_nid_param, msg,
+                                      msg->msg_rtr_nid_param);
                        if (rc) {
                                CERROR("Error sending %s to %s: %d\n",
                                       lnet_msgtyp2str(msg->msg_type),
@@ -3110,8 +3067,8 @@ static void
 lnet_recover_local_nis(void)
 {
        struct lnet_mt_event_info *ev_info;
-       struct list_head processed_list;
-       struct list_head local_queue;
+       LIST_HEAD(processed_list);
+       LIST_HEAD(local_queue);
        struct lnet_handle_md mdh;
        struct lnet_ni *tmp;
        struct lnet_ni *ni;
@@ -3119,9 +3076,6 @@ lnet_recover_local_nis(void)
        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
@@ -3223,7 +3177,7 @@ lnet_recover_local_nis(void)
                        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);
+                                           ev_info, the_lnet.ln_mt_eq, true);
                        /* lookup the nid again */
                        lnet_net_lock(0);
                        ni = lnet_nid2ni_locked(nid, 0);
@@ -3352,11 +3306,9 @@ static void
 lnet_clean_resendqs(void)
 {
        struct lnet_msg *msg, *tmp;
-       struct list_head msgs;
+       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);
@@ -3375,8 +3327,8 @@ static void
 lnet_recover_peer_nis(void)
 {
        struct lnet_mt_event_info *ev_info;
-       struct list_head processed_list;
-       struct list_head local_queue;
+       LIST_HEAD(processed_list);
+       LIST_HEAD(local_queue);
        struct lnet_handle_md mdh;
        struct lnet_peer_ni *lpni;
        struct lnet_peer_ni *tmp;
@@ -3384,9 +3336,6 @@ lnet_recover_peer_nis(void)
        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
@@ -3461,7 +3410,7 @@ lnet_recover_peer_nis(void)
                        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);
+                                           ev_info, the_lnet.ln_mt_eq, true);
                        lnet_net_lock(0);
                        /*
                         * lnet_find_peer_ni_locked() grabs a refcount for
@@ -3525,8 +3474,6 @@ lnet_monitor_thread(void *arg)
         *  4. Checks if there are any NIs on the remote recovery queue
         *     and pings them.
         */
-       cfs_block_allsigs();
-
        while (the_lnet.ln_mt_state == LNET_MT_STATE_RUNNING) {
                now = ktime_get_real_seconds();
 
@@ -3593,7 +3540,7 @@ lnet_monitor_thread(void *arg)
 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)
+              void *user_data, struct lnet_eq *eq, bool recovery)
 {
        struct lnet_md md = { NULL };
        struct lnet_process_id id;
@@ -3618,7 +3565,7 @@ lnet_send_ping(lnet_nid_t dest_nid,
        md.max_size  = 0;
        md.options   = LNET_MD_TRUNCATE;
        md.user_ptr  = user_data;
-       md.eq_handle = eqh;
+       md.eq_handle = eq;
 
        rc = LNetMDBind(md, LNET_UNLINK, mdh);
        if (rc) {
@@ -3813,7 +3760,7 @@ clean_thread:
        lnet_clean_local_ni_recoveryq();
        lnet_clean_peer_ni_recoveryq();
        lnet_clean_resendqs();
-       LNetInvalidateEQHandle(&the_lnet.ln_mt_eqh);
+       the_lnet.ln_mt_eq = NULL;
        return rc;
 clean_queues:
        lnet_rsp_tracker_clean();
@@ -4015,8 +3962,8 @@ lnet_parse_reply(struct lnet_ni *ni, struct lnet_msg *msg)
        struct lnet_hdr *hdr = &msg->msg_hdr;
        struct lnet_process_id src = {0};
        struct lnet_libmd *md;
-       int rlength;
-       int mlength;
+       unsigned int rlength;
+       unsigned int mlength;
        int cpt;
 
        cpt = lnet_cpt_of_cookie(hdr->msg.reply.dst_wmd.wh_object_cookie);
@@ -4045,7 +3992,7 @@ lnet_parse_reply(struct lnet_ni *ni, struct lnet_msg *msg)
        LASSERT(md->md_offset == 0);
 
        rlength = hdr->payload_length;
-       mlength = MIN(rlength, (int)md->md_length);
+       mlength = min(rlength, md->md_length);
 
        if (mlength < rlength &&
            (md->md_options & LNET_MD_TRUNCATE) == 0) {
@@ -4405,8 +4352,8 @@ lnet_parse(struct lnet_ni *ni, struct lnet_hdr *hdr, lnet_nid_t from_nid,
 
        if (!list_empty(&the_lnet.ln_drop_rules) &&
            lnet_drop_rule_match(hdr, ni->ni_nid, NULL)) {
-               CDEBUG(D_NET, "%s, src %s, dst %s: Dropping %s to simulate"
-                             "silent message loss\n",
+               CDEBUG(D_NET,
+                      "%s, src %s, dst %s: Dropping %s to simulate silent message loss\n",
                       libcfs_nid2str(from_nid), libcfs_nid2str(src_nid),
                       libcfs_nid2str(dest_nid), lnet_msgtyp2str(type));
                goto drop;
@@ -4655,7 +4602,6 @@ lnet_attach_rsp_tracker(struct lnet_rsp_tracker *rspt, int cpt,
                        struct lnet_libmd *md, struct lnet_handle_md mdh)
 {
        s64 timeout_ns;
-       bool new_entry = true;
        struct lnet_rsp_tracker *local_rspt;
 
        /*
@@ -4675,7 +4621,6 @@ lnet_attach_rsp_tracker(struct lnet_rsp_tracker *rspt, int cpt,
                 * update the deadline on that one.
                 */
                lnet_rspt_free(rspt, cpt);
-               new_entry = false;
        } else {
                /* new md */
                rspt->rspt_mdh = mdh;
@@ -4691,9 +4636,7 @@ lnet_attach_rsp_tracker(struct lnet_rsp_tracker *rspt, int cpt,
         * list in order to expire all the older entries first.
         */
        lnet_net_lock(cpt);
-       if (!new_entry && !list_empty(&local_rspt->rspt_on_list))
-               list_del_init(&local_rspt->rspt_on_list);
-       list_add_tail(&local_rspt->rspt_on_list, the_lnet.ln_mt_rstq[cpt]);
+       list_move_tail(&local_rspt->rspt_on_list, the_lnet.ln_mt_rstq[cpt]);
        lnet_net_unlock(cpt);
        lnet_res_unlock(cpt);
 }