Whamcloud - gitweb
LU-14661 lnet: Provide kernel API for adding peers
[fs/lustre-release.git] / lnet / lnet / peer.c
index 3719a74..33bd351 100644 (file)
@@ -27,7 +27,6 @@
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
- * Lustre is a trademark of Sun Microsystems, Inc.
  *
  * lnet/lnet/peer.c
  */
@@ -40,6 +39,7 @@
 #endif
 #include <linux/uaccess.h>
 
+#include <lnet/udsp.h>
 #include <lnet/lib-lnet.h>
 #include <uapi/linux/lnet/lnet-dlc.h>
 
@@ -166,7 +166,10 @@ lnet_peer_ni_alloc(lnet_nid_t nid)
        INIT_LIST_HEAD(&lpni->lpni_peer_nis);
        INIT_LIST_HEAD(&lpni->lpni_recovery);
        INIT_LIST_HEAD(&lpni->lpni_on_remote_peer_ni_list);
+       INIT_LIST_HEAD(&lpni->lpni_rtr_pref_nids);
        LNetInvalidateMDHandle(&lpni->lpni_recovery_ping_mdh);
+       kref_init(&lpni->lpni_kref);
+       lpni->lpni_sel_priority = LNET_MAX_SELECTION_PRIORITY;
 
        spin_lock_init(&lpni->lpni_lock);
 
@@ -194,7 +197,7 @@ lnet_peer_ni_alloc(lnet_nid_t nid)
                 * list so it can be easily found and revisited.
                 */
                /* FIXME: per-net implementation instead? */
-               atomic_inc(&lpni->lpni_refcount);
+               lnet_peer_ni_addref_locked(lpni);
                list_add_tail(&lpni->lpni_on_remote_peer_ni_list,
                              &the_lnet.ln_remote_peer_ni_list);
        }
@@ -216,6 +219,7 @@ lnet_peer_net_alloc(__u32 net_id)
        INIT_LIST_HEAD(&lpn->lpn_peer_nets);
        INIT_LIST_HEAD(&lpn->lpn_peer_nis);
        lpn->lpn_net_id = net_id;
+       lpn->lpn_sel_priority = LNET_MAX_SELECTION_PRIORITY;
 
        CDEBUG(D_NET, "%p net %s\n", lpn, libcfs_net2str(lpn->lpn_net_id));
 
@@ -259,6 +263,7 @@ lnet_peer_alloc(lnet_nid_t nid)
        spin_lock_init(&lp->lp_lock);
        lp->lp_primary_nid = nid;
        lp->lp_disc_src_nid = LNET_NID_ANY;
+       lp->lp_disc_dst_nid = LNET_NID_ANY;
        if (lnet_peers_start_down())
                lp->lp_alive = false;
        else
@@ -454,6 +459,10 @@ lnet_peer_del_locked(struct lnet_peer *peer)
 
        CDEBUG(D_NET, "peer %s\n", libcfs_nid2str(peer->lp_primary_nid));
 
+       spin_lock(&peer->lp_lock);
+       peer->lp_state |= LNET_PEER_MARK_DELETED;
+       spin_unlock(&peer->lp_lock);
+
        lpni = lnet_get_next_peer_ni_locked(peer, NULL, lpni);
        while (lpni != NULL) {
                lpni2 = lnet_get_next_peer_ni_locked(peer, NULL, lpni);
@@ -466,9 +475,41 @@ lnet_peer_del_locked(struct lnet_peer *peer)
        return rc2;
 }
 
+/*
+ * Discovering this peer is taking too long. Cancel any Ping or Push
+ * that discovery is waiting on by unlinking the relevant MDs. The
+ * lnet_discovery_event_handler() will proceed from here and complete
+ * the cleanup.
+ */
+static void lnet_peer_cancel_discovery(struct lnet_peer *lp)
+{
+       struct lnet_handle_md ping_mdh;
+       struct lnet_handle_md push_mdh;
+
+       LNetInvalidateMDHandle(&ping_mdh);
+       LNetInvalidateMDHandle(&push_mdh);
+
+       spin_lock(&lp->lp_lock);
+       if (lp->lp_state & LNET_PEER_PING_SENT) {
+               ping_mdh = lp->lp_ping_mdh;
+               LNetInvalidateMDHandle(&lp->lp_ping_mdh);
+       }
+       if (lp->lp_state & LNET_PEER_PUSH_SENT) {
+               push_mdh = lp->lp_push_mdh;
+               LNetInvalidateMDHandle(&lp->lp_push_mdh);
+       }
+       spin_unlock(&lp->lp_lock);
+
+       if (!LNetMDHandleIsInvalid(ping_mdh))
+               LNetMDUnlink(ping_mdh);
+       if (!LNetMDHandleIsInvalid(push_mdh))
+               LNetMDUnlink(push_mdh);
+}
+
 static int
 lnet_peer_del(struct lnet_peer *peer)
 {
+       lnet_peer_cancel_discovery(peer);
        lnet_net_lock(LNET_LOCK_EX);
        lnet_peer_del_locked(peer);
        lnet_net_unlock(LNET_LOCK_EX);
@@ -604,7 +645,7 @@ lnet_peer_table_del_rtrs_locked(struct lnet_net *net,
                        gw_nid = lp->lpni_peer_net->lpn_peer->lp_primary_nid;
 
                        lnet_net_unlock(LNET_LOCK_EX);
-                       lnet_del_route(LNET_NIDNET(LNET_NID_ANY), gw_nid);
+                       lnet_del_route(LNET_NET_ANY, gw_nid);
                        lnet_net_lock(LNET_LOCK_EX);
                }
        }
@@ -894,6 +935,94 @@ lnet_push_update_to_peers(int force)
        wake_up(&the_lnet.ln_dc_waitq);
 }
 
+/* find the NID in the preferred gateways for the remote peer
+ * return:
+ *     false: list is not empty and NID is not preferred
+ *     false: list is empty
+ *     true: nid is found in the list
+ */
+bool
+lnet_peer_is_pref_rtr_locked(struct lnet_peer_ni *lpni,
+                            lnet_nid_t gw_nid)
+{
+       struct lnet_nid_list *ne;
+
+       CDEBUG(D_NET, "%s: rtr pref emtpy: %d\n",
+              libcfs_nid2str(lpni->lpni_nid),
+              list_empty(&lpni->lpni_rtr_pref_nids));
+
+       if (list_empty(&lpni->lpni_rtr_pref_nids))
+               return false;
+
+       /* iterate through all the preferred NIDs and see if any of them
+        * matches the provided gw_nid
+        */
+       list_for_each_entry(ne, &lpni->lpni_rtr_pref_nids, nl_list) {
+               CDEBUG(D_NET, "Comparing pref %s with gw %s\n",
+                      libcfs_nid2str(ne->nl_nid),
+                      libcfs_nid2str(gw_nid));
+               if (ne->nl_nid == gw_nid)
+                       return true;
+       }
+
+       return false;
+}
+
+void
+lnet_peer_clr_pref_rtrs(struct lnet_peer_ni *lpni)
+{
+       struct list_head zombies;
+       struct lnet_nid_list *ne;
+       struct lnet_nid_list *tmp;
+       int cpt = lpni->lpni_cpt;
+
+       INIT_LIST_HEAD(&zombies);
+
+       lnet_net_lock(cpt);
+       list_splice_init(&lpni->lpni_rtr_pref_nids, &zombies);
+       lnet_net_unlock(cpt);
+
+       list_for_each_entry_safe(ne, tmp, &zombies, nl_list) {
+               list_del(&ne->nl_list);
+               LIBCFS_FREE(ne, sizeof(*ne));
+       }
+}
+
+int
+lnet_peer_add_pref_rtr(struct lnet_peer_ni *lpni,
+                      lnet_nid_t gw_nid)
+{
+       int cpt = lpni->lpni_cpt;
+       struct lnet_nid_list *ne = NULL;
+
+       /* This function is called with api_mutex held. When the api_mutex
+        * is held the list can not be modified, as it is only modified as
+        * a result of applying a UDSP and that happens under api_mutex
+        * lock.
+        */
+       __must_hold(&the_lnet.ln_api_mutex);
+
+       list_for_each_entry(ne, &lpni->lpni_rtr_pref_nids, nl_list) {
+               if (ne->nl_nid == gw_nid)
+                       return -EEXIST;
+       }
+
+       LIBCFS_CPT_ALLOC(ne, lnet_cpt_table(), cpt, sizeof(*ne));
+       if (!ne)
+               return -ENOMEM;
+
+       ne->nl_nid = gw_nid;
+
+       /* Lock the cpt to protect against addition and checks in the
+        * selection algorithm
+        */
+       lnet_net_lock(cpt);
+       list_add(&ne->nl_list, &lpni->lpni_rtr_pref_nids);
+       lnet_net_unlock(cpt);
+
+       return 0;
+}
+
 /*
  * Test whether a ni is a preferred ni for this peer_ni, e.g, whether
  * this is a preferred point-to-point path. Call with lnet_net_lock in
@@ -902,14 +1031,14 @@ lnet_push_update_to_peers(int force)
 bool
 lnet_peer_is_pref_nid_locked(struct lnet_peer_ni *lpni, lnet_nid_t nid)
 {
-       int i;
+       struct lnet_nid_list *ne;
 
        if (lpni->lpni_pref_nnids == 0)
                return false;
        if (lpni->lpni_pref_nnids == 1)
                return lpni->lpni_pref.nid == nid;
-       for (i = 0; i < lpni->lpni_pref_nnids; i++) {
-               if (lpni->lpni_pref.nids[i] == nid)
+       list_for_each_entry(ne, &lpni->lpni_pref.nids, nl_list) {
+               if (ne->nl_nid == nid)
                        return true;
        }
        return false;
@@ -966,6 +1095,12 @@ lnet_peer_ni_clr_non_mr_pref_nid(struct lnet_peer_ni *lpni)
        return rc;
 }
 
+void
+lnet_peer_ni_set_selection_priority(struct lnet_peer_ni *lpni, __u32 priority)
+{
+       lpni->lpni_sel_priority = priority;
+}
+
 /*
  * Clear the preferred NIDs from a non-multi-rail peer.
  */
@@ -981,11 +1116,10 @@ lnet_peer_clr_non_mr_pref_nids(struct lnet_peer *lp)
 int
 lnet_peer_add_pref_nid(struct lnet_peer_ni *lpni, lnet_nid_t nid)
 {
-       lnet_nid_t *nids = NULL;
-       lnet_nid_t *oldnids = NULL;
        struct lnet_peer *lp = lpni->lpni_peer_net->lpn_peer;
-       int size;
-       int i;
+       struct lnet_nid_list *ne1 = NULL;
+       struct lnet_nid_list *ne2 = NULL;
+       lnet_nid_t tmp_nid = LNET_NID_ANY;
        int rc = 0;
 
        if (nid == LNET_NID_ANY) {
@@ -999,29 +1133,47 @@ lnet_peer_add_pref_nid(struct lnet_peer_ni *lpni, lnet_nid_t nid)
        }
 
        /* A non-MR node may have only one preferred NI per peer_ni */
-       if (lpni->lpni_pref_nnids > 0) {
-               if (!(lp->lp_state & LNET_PEER_MULTI_RAIL)) {
-                       rc = -EPERM;
-                       goto out;
-               }
+       if (lpni->lpni_pref_nnids > 0 &&
+           !(lp->lp_state & LNET_PEER_MULTI_RAIL)) {
+               rc = -EPERM;
+               goto out;
        }
 
+       /* add the new preferred nid to the list of preferred nids */
        if (lpni->lpni_pref_nnids != 0) {
-               size = sizeof(*nids) * (lpni->lpni_pref_nnids + 1);
-               LIBCFS_CPT_ALLOC(nids, lnet_cpt_table(), lpni->lpni_cpt, size);
-               if (!nids) {
+               size_t alloc_size = sizeof(*ne1);
+
+               if (lpni->lpni_pref_nnids == 1) {
+                       tmp_nid = lpni->lpni_pref.nid;
+                       INIT_LIST_HEAD(&lpni->lpni_pref.nids);
+               }
+
+               list_for_each_entry(ne1, &lpni->lpni_pref.nids, nl_list) {
+                       if (ne1->nl_nid == nid) {
+                               rc = -EEXIST;
+                               goto out;
+                       }
+               }
+
+               LIBCFS_CPT_ALLOC(ne1, lnet_cpt_table(), lpni->lpni_cpt,
+                                alloc_size);
+               if (!ne1) {
                        rc = -ENOMEM;
                        goto out;
                }
-               for (i = 0; i < lpni->lpni_pref_nnids; i++) {
-                       if (lpni->lpni_pref.nids[i] == nid) {
-                               LIBCFS_FREE(nids, size);
-                               rc = -EEXIST;
+
+               /* move the originally stored nid to the list */
+               if (lpni->lpni_pref_nnids == 1) {
+                       LIBCFS_CPT_ALLOC(ne2, lnet_cpt_table(),
+                               lpni->lpni_cpt, alloc_size);
+                       if (!ne2) {
+                               rc = -ENOMEM;
                                goto out;
                        }
-                       nids[i] = lpni->lpni_pref.nids[i];
+                       INIT_LIST_HEAD(&ne2->nl_list);
+                       ne2->nl_nid = tmp_nid;
                }
-               nids[i] = nid;
+               ne1->nl_nid = nid;
        }
 
        lnet_net_lock(LNET_LOCK_EX);
@@ -1029,18 +1181,15 @@ lnet_peer_add_pref_nid(struct lnet_peer_ni *lpni, lnet_nid_t nid)
        if (lpni->lpni_pref_nnids == 0) {
                lpni->lpni_pref.nid = nid;
        } else {
-               oldnids = lpni->lpni_pref.nids;
-               lpni->lpni_pref.nids = nids;
+               if (ne2)
+                       list_add_tail(&ne2->nl_list, &lpni->lpni_pref.nids);
+               list_add_tail(&ne1->nl_list, &lpni->lpni_pref.nids);
        }
        lpni->lpni_pref_nnids++;
        lpni->lpni_state &= ~LNET_PEER_NI_NON_MR_PREF;
        spin_unlock(&lpni->lpni_lock);
        lnet_net_unlock(LNET_LOCK_EX);
 
-       if (oldnids) {
-               size = sizeof(*nids) * (lpni->lpni_pref_nnids - 1);
-               CFS_FREE_PTR_ARRAY(oldnids, size);
-       }
 out:
        if (rc == -EEXIST && (lpni->lpni_state & LNET_PEER_NI_NON_MR_PREF)) {
                spin_lock(&lpni->lpni_lock);
@@ -1055,11 +1204,8 @@ out:
 int
 lnet_peer_del_pref_nid(struct lnet_peer_ni *lpni, lnet_nid_t nid)
 {
-       lnet_nid_t *nids = NULL;
-       lnet_nid_t *oldnids = NULL;
        struct lnet_peer *lp = lpni->lpni_peer_net->lpn_peer;
-       int size;
-       int i, j;
+       struct lnet_nid_list *ne = NULL;
        int rc = 0;
 
        if (lpni->lpni_pref_nnids == 0) {
@@ -1072,61 +1218,71 @@ lnet_peer_del_pref_nid(struct lnet_peer_ni *lpni, lnet_nid_t nid)
                        rc = -ENOENT;
                        goto out;
                }
-       } else if (lpni->lpni_pref_nnids == 2) {
-               if (lpni->lpni_pref.nids[0] != nid &&
-                   lpni->lpni_pref.nids[1] != nid) {
-                       rc = -ENOENT;
-                       goto out;
-               }
        } else {
-               size = sizeof(*nids) * (lpni->lpni_pref_nnids - 1);
-               LIBCFS_CPT_ALLOC(nids, lnet_cpt_table(), lpni->lpni_cpt, size);
-               if (!nids) {
-                       rc = -ENOMEM;
-                       goto out;
-               }
-               for (i = 0, j = 0; i < lpni->lpni_pref_nnids; i++) {
-                       if (lpni->lpni_pref.nids[i] != nid)
-                               continue;
-                       nids[j++] = lpni->lpni_pref.nids[i];
-               }
-               /* Check if we actually removed a nid. */
-               if (j == lpni->lpni_pref_nnids) {
-                       LIBCFS_FREE(nids, size);
-                       rc = -ENOENT;
-                       goto out;
+               list_for_each_entry(ne, &lpni->lpni_pref.nids, nl_list) {
+                       if (ne->nl_nid == nid)
+                               goto remove_nid_entry;
                }
+               rc = -ENOENT;
+               ne = NULL;
+               goto out;
        }
 
+remove_nid_entry:
        lnet_net_lock(LNET_LOCK_EX);
        spin_lock(&lpni->lpni_lock);
-       if (lpni->lpni_pref_nnids == 1) {
+       if (lpni->lpni_pref_nnids == 1)
                lpni->lpni_pref.nid = LNET_NID_ANY;
-       } else if (lpni->lpni_pref_nnids == 2) {
-               oldnids = lpni->lpni_pref.nids;
-               if (oldnids[0] == nid)
-                       lpni->lpni_pref.nid = oldnids[1];
-               else
-                       lpni->lpni_pref.nid = oldnids[2];
-       } else {
-               oldnids = lpni->lpni_pref.nids;
-               lpni->lpni_pref.nids = nids;
+       else {
+               list_del_init(&ne->nl_list);
+               if (lpni->lpni_pref_nnids == 2) {
+                       struct lnet_nid_list *ne, *tmp;
+
+                       list_for_each_entry_safe(ne, tmp,
+                                                &lpni->lpni_pref.nids,
+                                                nl_list) {
+                               lpni->lpni_pref.nid = ne->nl_nid;
+                               list_del_init(&ne->nl_list);
+                               LIBCFS_FREE(ne, sizeof(*ne));
+                       }
+               }
        }
        lpni->lpni_pref_nnids--;
        lpni->lpni_state &= ~LNET_PEER_NI_NON_MR_PREF;
        spin_unlock(&lpni->lpni_lock);
        lnet_net_unlock(LNET_LOCK_EX);
 
-       if (oldnids) {
-               size = sizeof(*nids) * (lpni->lpni_pref_nnids + 1);
-               CFS_FREE_PTR_ARRAY(oldnids, size);
-       }
+       if (ne)
+               LIBCFS_FREE(ne, sizeof(*ne));
 out:
        CDEBUG(D_NET, "peer %s nid %s: %d\n",
               libcfs_nid2str(lp->lp_primary_nid), libcfs_nid2str(nid), rc);
        return rc;
 }
 
+void
+lnet_peer_clr_pref_nids(struct lnet_peer_ni *lpni)
+{
+       struct list_head zombies;
+       struct lnet_nid_list *ne;
+       struct lnet_nid_list *tmp;
+
+       INIT_LIST_HEAD(&zombies);
+
+       lnet_net_lock(LNET_LOCK_EX);
+       if (lpni->lpni_pref_nnids == 1)
+               lpni->lpni_pref.nid = LNET_NID_ANY;
+       else if (lpni->lpni_pref_nnids > 1)
+               list_splice_init(&lpni->lpni_pref.nids, &zombies);
+       lpni->lpni_pref_nnids = 0;
+       lnet_net_unlock(LNET_LOCK_EX);
+
+       list_for_each_entry_safe(ne, tmp, &zombies, nl_list) {
+               list_del_init(&ne->nl_list);
+               LIBCFS_FREE(ne, sizeof(*ne));
+       }
+}
+
 lnet_nid_t
 lnet_peer_primary_nid_locked(lnet_nid_t nid)
 {
@@ -1172,6 +1328,51 @@ lnet_is_discovery_disabled(struct lnet_peer *lp)
        return rc;
 }
 
+int
+LNetAddPeer(lnet_nid_t *nids, __u32 num_nids)
+{
+       lnet_nid_t pnid = 0;
+       bool mr;
+       int i, rc;
+
+       if (!nids || num_nids < 1)
+               return -EINVAL;
+
+       rc = LNetNIInit(LNET_PID_ANY);
+       if (rc < 0)
+               return rc;
+
+       mutex_lock(&the_lnet.ln_api_mutex);
+
+       mr = lnet_peer_discovery_disabled == 0;
+
+       rc = 0;
+       for (i = 0; i < num_nids; i++) {
+               if (nids[i] == LNET_NID_LO_0)
+                       continue;
+
+               if (!pnid) {
+                       pnid = nids[i];
+                       rc = lnet_add_peer_ni(pnid, LNET_NID_ANY, mr, true);
+               } else if (lnet_peer_discovery_disabled) {
+                       rc = lnet_add_peer_ni(nids[i], LNET_NID_ANY, mr, true);
+               } else {
+                       rc = lnet_add_peer_ni(pnid, nids[i], mr, true);
+               }
+
+               if (rc && rc != -EEXIST)
+                       goto unlock;
+       }
+
+unlock:
+       mutex_unlock(&the_lnet.ln_api_mutex);
+
+       LNetNIFini();
+
+       return rc == -EEXIST ? 0 : rc;
+}
+EXPORT_SYMBOL(LNetAddPeer);
+
 lnet_nid_t
 LNetPrimaryNID(lnet_nid_t nid)
 {
@@ -1192,13 +1393,38 @@ LNetPrimaryNID(lnet_nid_t nid)
        }
        lp = lpni->lpni_peer_net->lpn_peer;
 
-       while (!lnet_peer_is_uptodate(lp)) {
+       /* If discovery is disabled locally then we needn't bother running
+        * discovery here because discovery will not modify whatever
+        * primary NID is currently set for this peer. If the specified peer is
+        * down then this discovery can introduce long delays into the mount
+        * process, so skip it if it isn't necessary.
+        */
+       while (!lnet_peer_discovery_disabled && !lnet_peer_is_uptodate(lp)) {
+               spin_lock(&lp->lp_lock);
+               /* force a full discovery cycle */
+               lp->lp_state |= LNET_PEER_FORCE_PING | LNET_PEER_FORCE_PUSH;
+               spin_unlock(&lp->lp_lock);
+
                rc = lnet_discover_peer_locked(lpni, cpt, true);
                if (rc)
                        goto out_decref;
+               /* The lpni (or lp) for this NID may have changed and our ref is
+                * the only thing keeping the old one around. Release the ref
+                * and lookup the lpni again
+                */
+               lnet_peer_ni_decref_locked(lpni);
+               lpni = lnet_find_peer_ni_locked(nid);
+               if (!lpni) {
+                       rc = -ENOENT;
+                       goto out_unlock;
+               }
                lp = lpni->lpni_peer_net->lpn_peer;
 
-               /* Only try once if discovery is disabled */
+               /* If we find that the peer has discovery disabled then we will
+                * not modify whatever primary NID is currently set for this
+                * peer. Thus, we can break out of this loop even if the peer
+                * is not fully up to date.
+                */
                if (lnet_is_discovery_disabled(lp))
                        break;
        }
@@ -1231,9 +1457,9 @@ lnet_peer_get_net_locked(struct lnet_peer *peer, __u32 net_id)
  * may be attached to a different peer, in which case it will be
  * properly detached first. The whole operation is done atomically.
  *
- * Always returns 0.  This is the last function called from functions
- * that do return an int, so returning 0 here allows the compiler to
- * do a tail call.
+ * This function consumes the reference on lpni and Always returns 0.
+ * This is the last function called from functions that do return an
+ * int, so returning 0 here allows the compiler to do a tail call.
  */
 static int
 lnet_peer_attach_peer_ni(struct lnet_peer *lp,
@@ -1242,6 +1468,8 @@ lnet_peer_attach_peer_ni(struct lnet_peer *lp,
                                unsigned flags)
 {
        struct lnet_peer_table *ptable;
+       bool new_lpn = false;
+       int rc;
 
        /* Install the new peer_ni */
        lnet_net_lock(LNET_LOCK_EX);
@@ -1252,8 +1480,7 @@ lnet_peer_attach_peer_ni(struct lnet_peer *lp,
                ptable = the_lnet.ln_peer_tables[lpni->lpni_cpt];
                list_add_tail(&lpni->lpni_hashlist, &ptable->pt_hash[hash]);
                ptable->pt_version++;
-               /* This is the 1st refcount on lpni. */
-               atomic_inc(&lpni->lpni_refcount);
+               lnet_peer_ni_addref_locked(lpni);
        }
 
        /* Detach the peer_ni from an existing peer, if necessary. */
@@ -1267,14 +1494,21 @@ lnet_peer_attach_peer_ni(struct lnet_peer *lp,
 
        /* Add peer_ni to peer_net */
        lpni->lpni_peer_net = lpn;
-       list_add_tail(&lpni->lpni_peer_nis, &lpn->lpn_peer_nis);
+       if (lp->lp_primary_nid == lpni->lpni_nid)
+               list_add(&lpni->lpni_peer_nis, &lpn->lpn_peer_nis);
+       else
+               list_add_tail(&lpni->lpni_peer_nis, &lpn->lpn_peer_nis);
        lnet_update_peer_net_healthv(lpni);
        lnet_peer_net_addref_locked(lpn);
 
        /* Add peer_net to peer */
        if (!lpn->lpn_peer) {
+               new_lpn = true;
                lpn->lpn_peer = lp;
-               list_add_tail(&lpn->lpn_peer_nets, &lp->lp_peer_nets);
+               if (lp->lp_primary_nid == lpni->lpni_nid)
+                       list_add(&lpn->lpn_peer_nets, &lp->lp_peer_nets);
+               else
+                       list_add_tail(&lpn->lpn_peer_nets, &lp->lp_peer_nets);
                lnet_peer_addref_locked(lp);
        }
 
@@ -1301,11 +1535,24 @@ lnet_peer_attach_peer_ni(struct lnet_peer *lp,
        spin_unlock(&lp->lp_lock);
 
        lp->lp_nnis++;
-       lnet_net_unlock(LNET_LOCK_EX);
+
+       /* apply UDSPs */
+       if (new_lpn) {
+               rc = lnet_udsp_apply_policies_on_lpn(lpn);
+               if (rc)
+                       CERROR("Failed to apply UDSPs on lpn %s\n",
+                              libcfs_net2str(lpn->lpn_net_id));
+       }
+       rc = lnet_udsp_apply_policies_on_lpni(lpni);
+       if (rc)
+               CERROR("Failed to apply UDSPs on lpni %s\n",
+                      libcfs_nid2str(lpni->lpni_nid));
 
        CDEBUG(D_NET, "peer %s NID %s flags %#x\n",
               libcfs_nid2str(lp->lp_primary_nid),
               libcfs_nid2str(lpni->lpni_nid), flags);
+       lnet_peer_ni_decref_locked(lpni);
+       lnet_net_unlock(LNET_LOCK_EX);
 
        return 0;
 }
@@ -1346,6 +1593,11 @@ lnet_peer_add(lnet_nid_t nid, unsigned flags)
                        else if ((lp->lp_state ^ flags) & LNET_PEER_MULTI_RAIL)
                                rc = -EPERM;
                        goto out;
+               } else if (!(flags & LNET_PEER_CONFIGURED)) {
+                       if (lp->lp_primary_nid == nid) {
+                               rc = -EEXIST;
+                               goto out;
+                       }
                }
                /* Delete and recreate as a configured peer. */
                lnet_peer_del(lp);
@@ -1426,17 +1678,16 @@ lnet_peer_add_nid(struct lnet_peer *lp, lnet_nid_t nid, unsigned flags)
                 * it is not connected to this peer and was configured
                 * by DLC.
                 */
-               lnet_peer_ni_decref_locked(lpni);
                if (lpni->lpni_peer_net->lpn_peer == lp)
-                       goto out;
+                       goto out_free_lpni;
                if (lnet_peer_ni_is_configured(lpni)) {
                        rc = -EEXIST;
-                       goto out;
+                       goto out_free_lpni;
                }
                /* If this is the primary NID, destroy the peer. */
                if (lnet_peer_ni_is_primary(lpni)) {
                        struct lnet_peer *rtr_lp =
-                         lpni->lpni_peer_net->lpn_peer;
+                               lpni->lpni_peer_net->lpn_peer;
                        int rtr_refcount = rtr_lp->lp_rtr_refcount;
                        /*
                         * if we're trying to delete a router it means
@@ -1448,17 +1699,18 @@ lnet_peer_add_nid(struct lnet_peer *lp, lnet_nid_t nid, unsigned flags)
                                lnet_rtr_transfer_to_peer(rtr_lp, lp);
                        }
                        lnet_peer_del(lpni->lpni_peer_net->lpn_peer);
+                       lnet_peer_ni_decref_locked(lpni);
                        lpni = lnet_peer_ni_alloc(nid);
                        if (!lpni) {
                                rc = -ENOMEM;
-                               goto out;
+                               goto out_free_lpni;
                        }
                }
        } else {
                lpni = lnet_peer_ni_alloc(nid);
                if (!lpni) {
                        rc = -ENOMEM;
-                       goto out;
+                       goto out_free_lpni;
                }
        }
 
@@ -1481,9 +1733,7 @@ lnet_peer_add_nid(struct lnet_peer *lp, lnet_nid_t nid, unsigned flags)
        return lnet_peer_attach_peer_ni(lp, lpn, lpni, flags);
 
 out_free_lpni:
-       /* If the peer_ni was allocated above its peer_net pointer is NULL */
-       if (!lpni->lpni_peer_net)
-               LIBCFS_FREE(lpni, sizeof(*lpni));
+       lnet_peer_ni_decref_locked(lpni);
 out:
        CDEBUG(D_NET, "peer %s NID %s flags %#x: %d\n",
               libcfs_nid2str(lp->lp_primary_nid), libcfs_nid2str(nid),
@@ -1504,10 +1754,14 @@ lnet_peer_set_primary_nid(struct lnet_peer *lp, lnet_nid_t nid, unsigned flags)
 
        if (lp->lp_primary_nid == nid)
                goto out;
+
+       lp->lp_primary_nid = nid;
+
        rc = lnet_peer_add_nid(lp, nid, flags);
-       if (rc)
+       if (rc) {
+               lp->lp_primary_nid = old;
                goto out;
-       lp->lp_primary_nid = nid;
+       }
 out:
        CDEBUG(D_NET, "peer %s NID %s: %d\n",
               libcfs_nid2str(old), libcfs_nid2str(nid), rc);
@@ -1582,17 +1836,19 @@ out:
  * being created/modified/deleted by a different thread.
  */
 int
-lnet_add_peer_ni(lnet_nid_t prim_nid, lnet_nid_t nid, bool mr)
+lnet_add_peer_ni(lnet_nid_t prim_nid, lnet_nid_t nid, bool mr, bool temp)
 {
        struct lnet_peer *lp = NULL;
        struct lnet_peer_ni *lpni;
-       unsigned flags;
+       unsigned int flags = 0;
 
        /* The prim_nid must always be specified */
        if (prim_nid == LNET_NID_ANY)
                return -EINVAL;
 
-       flags = LNET_PEER_CONFIGURED;
+       if (!temp)
+               flags = LNET_PEER_CONFIGURED;
+
        if (mr)
                flags |= LNET_PEER_MULTI_RAIL;
 
@@ -1611,7 +1867,7 @@ lnet_add_peer_ni(lnet_nid_t prim_nid, lnet_nid_t nid, bool mr)
        lp = lpni->lpni_peer_net->lpn_peer;
 
        /* Peer must have been configured. */
-       if (!(lp->lp_state & LNET_PEER_CONFIGURED)) {
+       if (!temp && !(lp->lp_state & LNET_PEER_CONFIGURED)) {
                CDEBUG(D_NET, "peer %s was not configured\n",
                       libcfs_nid2str(prim_nid));
                return -ENOENT;
@@ -1689,14 +1945,16 @@ lnet_del_peer_ni(lnet_nid_t prim_nid, lnet_nid_t nid)
 }
 
 void
-lnet_destroy_peer_ni_locked(struct lnet_peer_ni *lpni)
+lnet_destroy_peer_ni_locked(struct kref *ref)
 {
+       struct lnet_peer_ni *lpni = container_of(ref, struct lnet_peer_ni,
+                                                lpni_kref);
        struct lnet_peer_table *ptable;
        struct lnet_peer_net *lpn;
 
        CDEBUG(D_NET, "%p nid %s\n", lpni, libcfs_nid2str(lpni->lpni_nid));
 
-       LASSERT(atomic_read(&lpni->lpni_refcount) == 0);
+       LASSERT(kref_read(&lpni->lpni_kref) == 0);
        LASSERT(list_empty(&lpni->lpni_txq));
        LASSERT(lpni->lpni_txqnob == 0);
        LASSERT(list_empty(&lpni->lpni_peer_nis));
@@ -1706,19 +1964,28 @@ lnet_destroy_peer_ni_locked(struct lnet_peer_ni *lpni)
        lpni->lpni_peer_net = NULL;
        lpni->lpni_net = NULL;
 
-       /* remove the peer ni from the zombie list */
-       ptable = the_lnet.ln_peer_tables[lpni->lpni_cpt];
-       spin_lock(&ptable->pt_zombie_lock);
-       list_del_init(&lpni->lpni_hashlist);
-       ptable->pt_zombies--;
-       spin_unlock(&ptable->pt_zombie_lock);
+       if (!list_empty(&lpni->lpni_hashlist)) {
+               /* remove the peer ni from the zombie list */
+               ptable = the_lnet.ln_peer_tables[lpni->lpni_cpt];
+               spin_lock(&ptable->pt_zombie_lock);
+               list_del_init(&lpni->lpni_hashlist);
+               ptable->pt_zombies--;
+               spin_unlock(&ptable->pt_zombie_lock);
+       }
 
-       if (lpni->lpni_pref_nnids > 1)
-               CFS_FREE_PTR_ARRAY(lpni->lpni_pref.nids, lpni->lpni_pref_nnids);
+       if (lpni->lpni_pref_nnids > 1) {
+               struct lnet_nid_list *ne, *tmp;
 
+               list_for_each_entry_safe(ne, tmp, &lpni->lpni_pref.nids,
+                                        nl_list) {
+                       list_del_init(&ne->nl_list);
+                       LIBCFS_FREE(ne, sizeof(*ne));
+               }
+       }
        LIBCFS_FREE(lpni, sizeof(*lpni));
 
-       lnet_peer_net_decref_locked(lpn);
+       if (lpn)
+               lnet_peer_net_decref_locked(lpn);
 }
 
 struct lnet_peer_ni *
@@ -1880,6 +2147,26 @@ __must_hold(&lp->lp_lock)
        return rc;
 }
 
+/* Add the message to the peer's lp_dc_pendq and queue the peer for discovery */
+void
+lnet_peer_queue_message(struct lnet_peer *lp, struct lnet_msg *msg)
+{
+       /* The discovery thread holds net_lock/EX and lp_lock when it splices
+        * the lp_dc_pendq onto a local list for resending. Thus, we do the same
+        * when adding to the list and queuing the peer to ensure that we do not
+        * strand any messages on the lp_dc_pendq. This scheme ensures the
+        * message will be resent even if the peer is already being discovered.
+        * Therefore we needn't check the return value of
+        * lnet_peer_queue_for_discovery(lp).
+        */
+       lnet_net_lock(LNET_LOCK_EX);
+       spin_lock(&lp->lp_lock);
+       list_add_tail(&msg->msg_list, &lp->lp_dc_pendq);
+       spin_unlock(&lp->lp_lock);
+       lnet_peer_queue_for_discovery(lp);
+       lnet_net_unlock(LNET_LOCK_EX);
+}
+
 /*
  * Queue a peer for the attention of the discovery thread.  Call with
  * lnet_net_lock/EX held. Returns 0 if the peer was queued, and
@@ -1925,7 +2212,7 @@ static void lnet_peer_discovery_complete(struct lnet_peer *lp)
        spin_lock(&lp->lp_lock);
        list_splice_init(&lp->lp_dc_pendq, &pending_msgs);
        spin_unlock(&lp->lp_lock);
-       wake_up_all(&lp->lp_dc_waitq);
+       wake_up(&lp->lp_dc_waitq);
 
        if (lp->lp_rtr_refcount > 0)
                lnet_router_discovery_complete(lp);
@@ -2032,13 +2319,17 @@ void lnet_peer_push_event(struct lnet_event *ev)
                CDEBUG(D_NET, "Peer %s has discovery disabled\n",
                       libcfs_nid2str(lp->lp_primary_nid));
                /*
-                * If the peer is going from discovery enabled to
-                * discovery disabled, we need to reflect that in our
-                * representation of the peer.
+                * Mark the peer for deletion if we already know about it
+                * and it's going from discovery set to no discovery set
                 */
                if (!(lp->lp_state & (LNET_PEER_NO_DISCOVERY |
-                                     LNET_PEER_DISCOVERING)))
+                                     LNET_PEER_DISCOVERING)) &&
+                    lp->lp_state & LNET_PEER_DISCOVERED) {
+                       CDEBUG(D_NET, "Marking %s:0x%x for deletion\n",
+                              libcfs_nid2str(lp->lp_primary_nid),
+                              lp->lp_state);
                        lp->lp_state |= LNET_PEER_MARK_DELETION;
+               }
                lp->lp_state |= LNET_PEER_NO_DISCOVERY;
        } else if (lp->lp_state & LNET_PEER_NO_DISCOVERY) {
                CDEBUG(D_NET, "Peer %s has discovery enabled\n",
@@ -2293,6 +2584,7 @@ lnet_discovery_event_reply(struct lnet_peer *lp, struct lnet_event *ev)
        spin_lock(&lp->lp_lock);
 
        lp->lp_disc_src_nid = ev->target.nid;
+       lp->lp_disc_dst_nid = ev->source.nid;
 
        /*
         * If some kind of error happened the contents of message
@@ -2325,20 +2617,41 @@ lnet_discovery_event_reply(struct lnet_peer *lp, struct lnet_event *ev)
                goto out;
        }
 
-
        /*
         * The peer may have discovery disabled at its end. Set
         * NO_DISCOVERY as appropriate.
         */
-       if ((pbuf->pb_info.pi_features & LNET_PING_FEAT_DISCOVERY) &&
-           !lnet_peer_discovery_disabled) {
-               CDEBUG(D_NET, "Peer %s has discovery enabled\n",
-                      libcfs_nid2str(lp->lp_primary_nid));
-               lp->lp_state &= ~LNET_PEER_NO_DISCOVERY;
-       } else {
+       if (!(pbuf->pb_info.pi_features & LNET_PING_FEAT_DISCOVERY) ||
+           lnet_peer_discovery_disabled) {
                CDEBUG(D_NET, "Peer %s has discovery disabled\n",
                       libcfs_nid2str(lp->lp_primary_nid));
+
+               /* Detect whether this peer has toggled discovery from on to
+                * off and whether we can delete and re-create the peer. Peers
+                * that were manually configured cannot be deleted by discovery.
+                * We need to delete this peer and re-create it if the peer was
+                * not configured manually, is currently considered DD capable,
+                * and either:
+                * 1. We've already discovered the peer (the peer has toggled
+                *    the discovery feature from on to off), or
+                * 2. The peer is considered MR, but it was not user configured
+                *    (this was a "temporary" peer created via the kernel APIs
+                *     that we're discovering for the first time)
+                */
+               if (!(lp->lp_state & (LNET_PEER_CONFIGURED |
+                                     LNET_PEER_NO_DISCOVERY)) &&
+                   (lp->lp_state & (LNET_PEER_DISCOVERED |
+                                    LNET_PEER_MULTI_RAIL))) {
+                       CDEBUG(D_NET, "Marking %s:0x%x for deletion\n",
+                              libcfs_nid2str(lp->lp_primary_nid),
+                              lp->lp_state);
+                       lp->lp_state |= LNET_PEER_MARK_DELETION;
+               }
                lp->lp_state |= LNET_PEER_NO_DISCOVERY;
+       } else {
+               CDEBUG(D_NET, "Peer %s has discovery enabled\n",
+                      libcfs_nid2str(lp->lp_primary_nid));
+               lp->lp_state &= ~LNET_PEER_NO_DISCOVERY;
        }
 
        /*
@@ -2546,7 +2859,8 @@ static void lnet_discovery_event_handler(struct lnet_event *event)
 
        /* put peer back at end of request queue, if discovery not already
         * done */
-       if (rc == LNET_REDISCOVER_PEER && !lnet_peer_is_uptodate(lp)) {
+       if (rc == LNET_REDISCOVER_PEER && !lnet_peer_is_uptodate(lp) &&
+           lnet_peer_queue_for_discovery(lp)) {
                list_move_tail(&lp->lp_dc_list, &the_lnet.ln_dc_request);
                wake_up(&the_lnet.ln_dc_waitq);
        }
@@ -2574,6 +2888,7 @@ static void lnet_discovery_event_handler(struct lnet_event *event)
 static int lnet_peer_merge_data(struct lnet_peer *lp,
                                struct lnet_ping_buffer *pbuf)
 {
+       struct lnet_peer_net *lpn;
        struct lnet_peer_ni *lpni;
        lnet_nid_t *curnis = NULL;
        struct lnet_ni_status *addnis = NULL;
@@ -2702,6 +3017,28 @@ static int lnet_peer_merge_data(struct lnet_peer *lp,
                                goto out;
                }
        }
+
+       /* The peer net for the primary NID should be the first entry in the
+        * peer's lp_peer_nets list, and the peer NI for the primary NID should
+        * be the first entry in its peer net's lpn_peer_nis list.
+        */
+       lpni = lnet_find_peer_ni_locked(pbuf->pb_info.pi_ni[1].ns_nid);
+       if (!lpni) {
+               CERROR("Internal error: Failed to lookup peer NI for primary NID: %s\n",
+                      libcfs_nid2str(pbuf->pb_info.pi_ni[1].ns_nid));
+               goto out;
+       }
+
+       lnet_peer_ni_decref_locked(lpni);
+
+       lpn = lpni->lpni_peer_net;
+       if (lpn->lpn_peer_nets.prev != &lp->lp_peer_nets)
+               list_move(&lpn->lpn_peer_nets, &lp->lp_peer_nets);
+
+       if (lpni->lpni_peer_nis.prev != &lpni->lpni_peer_net->lpn_peer_nis)
+               list_move(&lpni->lpni_peer_nis,
+                         &lpni->lpni_peer_net->lpn_peer_nis);
+
        /*
         * Errors other than -ENOMEM are due to peers having been
         * configured with DLC. Ignore these because DLC overrides
@@ -2798,6 +3135,72 @@ static bool lnet_is_nid_in_ping_info(lnet_nid_t nid, struct lnet_ping_info *pinf
        return false;
 }
 
+/* Delete a peer that has been marked for deletion. NB: when this peer was added
+ * to the discovery queue a reference was taken that will prevent the peer from
+ * actually being freed by this function. After this function exits the
+ * discovery thread should call lnet_peer_discovery_complete() which will
+ * drop that reference as well as wake any waiters that may also be holding a
+ * ref on the peer
+ */
+static int lnet_peer_deletion(struct lnet_peer *lp)
+__must_hold(&lp->lp_lock)
+{
+       struct list_head rlist;
+       struct lnet_route *route, *tmp;
+       int sensitivity = lp->lp_health_sensitivity;
+
+       INIT_LIST_HEAD(&rlist);
+
+       lp->lp_state &= ~(LNET_PEER_DISCOVERING | LNET_PEER_FORCE_PING |
+                         LNET_PEER_FORCE_PUSH);
+       CDEBUG(D_NET, "peer %s(%p) state %#x\n",
+              libcfs_nid2str(lp->lp_primary_nid), lp, lp->lp_state);
+
+       /* no-op if lnet_peer_del() has already been called on this peer */
+       if (lp->lp_state & LNET_PEER_MARK_DELETED)
+               return 0;
+
+       if (the_lnet.ln_dc_state != LNET_DC_STATE_RUNNING)
+               return -ESHUTDOWN;
+
+       spin_unlock(&lp->lp_lock);
+
+       mutex_lock(&the_lnet.ln_api_mutex);
+
+       lnet_net_lock(LNET_LOCK_EX);
+       /* remove the peer from the discovery work
+        * queue if it's on there in preparation
+        * of deleting it.
+        */
+       if (!list_empty(&lp->lp_dc_list))
+               list_del_init(&lp->lp_dc_list);
+       list_for_each_entry_safe(route, tmp,
+                                &lp->lp_routes,
+                                lr_gwlist)
+               lnet_move_route(route, NULL, &rlist);
+       lnet_net_unlock(LNET_LOCK_EX);
+
+       /* lnet_peer_del() deletes all the peer NIs owned by this peer */
+       lnet_peer_del(lp);
+
+       list_for_each_entry_safe(route, tmp,
+                                &rlist, lr_list) {
+               /* re-add these routes */
+               lnet_add_route(route->lr_net,
+                              route->lr_hops,
+                              route->lr_nid,
+                              route->lr_priority,
+                              sensitivity);
+               LIBCFS_FREE(route, sizeof(*route));
+       }
+
+       mutex_unlock(&the_lnet.ln_api_mutex);
+
+       spin_lock(&lp->lp_lock);
+
+       return 0;
+}
+
 /*
  * Update a peer using the data received.
  */
@@ -2879,7 +3282,7 @@ __must_hold(&lp->lp_lock)
                rc = lnet_peer_merge_data(lp, pbuf);
        } else {
                lpni = lnet_find_peer_ni_locked(nid);
-               if (!lpni) {
+               if (!lpni || lp == lpni->lpni_peer_net->lpn_peer) {
                        rc = lnet_peer_set_primary_nid(lp, nid, flags);
                        if (rc) {
                                CERROR("Primary NID error %s versus %s: %d\n",
@@ -2888,6 +3291,8 @@ __must_hold(&lp->lp_lock)
                        } else {
                                rc = lnet_peer_merge_data(lp, pbuf);
                        }
+                       if (lpni)
+                               lnet_peer_ni_decref_locked(lpni);
                } else {
                        struct lnet_peer *new_lp;
                        new_lp = lpni->lpni_peer_net->lpn_peer;
@@ -2896,10 +3301,24 @@ __must_hold(&lp->lp_lock)
                         * should have discovery/MR enabled as well, since
                         * it's the same peer, which we're about to merge
                         */
+                       spin_lock(&lp->lp_lock);
+                       spin_lock(&new_lp->lp_lock);
                        if (!(lp->lp_state & LNET_PEER_NO_DISCOVERY))
                                new_lp->lp_state &= ~LNET_PEER_NO_DISCOVERY;
                        if (lp->lp_state & LNET_PEER_MULTI_RAIL)
                                new_lp->lp_state |= LNET_PEER_MULTI_RAIL;
+                       /* If we're processing a ping reply then we may be
+                        * about to send a push to the peer that we ping'd.
+                        * Since the ping reply that we're processing was
+                        * received by lp, we need to set the discovery source
+                        * NID for new_lp to the NID stored in lp.
+                        */
+                       if (lp->lp_disc_src_nid != LNET_NID_ANY) {
+                               new_lp->lp_disc_src_nid = lp->lp_disc_src_nid;
+                               new_lp->lp_disc_dst_nid = lp->lp_disc_dst_nid;
+                       }
+                       spin_unlock(&new_lp->lp_lock);
+                       spin_unlock(&lp->lp_lock);
 
                        rc = lnet_peer_set_primary_data(new_lp, pbuf);
                        lnet_consolidate_routes_locked(lp, new_lp);
@@ -2947,41 +3366,10 @@ __must_hold(&lp->lp_lock)
        return rc ? rc : LNET_REDISCOVER_PEER;
 }
 
-/*
- * Select NID to send a Ping or Push to.
- */
-static lnet_nid_t lnet_peer_select_nid(struct lnet_peer *lp)
-{
-       struct lnet_peer_ni *lpni;
-
-       /* Look for a direct-connected NID for this peer. */
-       lpni = NULL;
-       while ((lpni = lnet_get_next_peer_ni_locked(lp, NULL, lpni)) != NULL) {
-               if (!lnet_get_net_locked(lpni->lpni_peer_net->lpn_net_id))
-                       continue;
-               break;
-       }
-       if (lpni)
-               return lpni->lpni_nid;
-
-       /* Look for a routed-connected NID for this peer. */
-       lpni = NULL;
-       while ((lpni = lnet_get_next_peer_ni_locked(lp, NULL, lpni)) != NULL) {
-               if (!lnet_find_rnet_locked(lpni->lpni_peer_net->lpn_net_id))
-                       continue;
-               break;
-       }
-       if (lpni)
-               return lpni->lpni_nid;
-
-       return LNET_NID_ANY;
-}
-
 /* Active side of ping. */
 static int lnet_peer_send_ping(struct lnet_peer *lp)
 __must_hold(&lp->lp_lock)
 {
-       lnet_nid_t pnid;
        int nnis;
        int rc;
        int cpt;
@@ -2993,12 +3381,11 @@ __must_hold(&lp->lp_lock)
        cpt = lnet_net_lock_current();
        /* Refcount for MD. */
        lnet_peer_addref_locked(lp);
-       pnid = lnet_peer_select_nid(lp);
        lnet_net_unlock(cpt);
 
        nnis = max(lp->lp_data_nnis, LNET_INTERFACES_MIN);
 
-       rc = lnet_send_ping(pnid, &lp->lp_ping_mdh, nnis, lp,
+       rc = lnet_send_ping(lp->lp_primary_nid, &lp->lp_ping_mdh, nnis, lp,
                            the_lnet.ln_dc_handler, false);
 
        /*
@@ -3060,6 +3447,23 @@ __must_hold(&lp->lp_lock)
        return rc ? rc : LNET_REDISCOVER_PEER;
 }
 
+/*
+ * Mark the peer as discovered.
+ */
+static int lnet_peer_discovered(struct lnet_peer *lp)
+__must_hold(&lp->lp_lock)
+{
+       lp->lp_state |= LNET_PEER_DISCOVERED;
+       lp->lp_state &= ~(LNET_PEER_DISCOVERING |
+                         LNET_PEER_REDISCOVER);
+
+       lp->lp_dc_error = 0;
+
+       CDEBUG(D_NET, "peer %s\n", libcfs_nid2str(lp->lp_primary_nid));
+
+       return 0;
+}
+
 /* Active side of push. */
 static int lnet_peer_send_push(struct lnet_peer *lp)
 __must_hold(&lp->lp_lock)
@@ -3073,6 +3477,12 @@ __must_hold(&lp->lp_lock)
        /* Don't push to a non-multi-rail peer. */
        if (!(lp->lp_state & LNET_PEER_MULTI_RAIL)) {
                lp->lp_state &= ~LNET_PEER_FORCE_PUSH;
+               /* if peer's NIDs are uptodate then peer is discovered */
+               if (lp->lp_state & LNET_PEER_NIDS_UPTODATE) {
+                       rc = lnet_peer_discovered(lp);
+                       return rc;
+               }
+
                return 0;
        }
 
@@ -3090,28 +3500,27 @@ __must_hold(&lp->lp_lock)
        md.length    = LNET_PING_INFO_SIZE(pbuf->pb_nnis);
        md.threshold = 2; /* Put/Ack */
        md.max_size  = 0;
-       md.options   = 0;
+       md.options   = LNET_MD_TRACK_RESPONSE;
        md.handler   = the_lnet.ln_dc_handler;
        md.user_ptr  = lp;
 
-       rc = LNetMDBind(md, LNET_UNLINK, &lp->lp_push_mdh);
+       rc = LNetMDBind(&md, LNET_UNLINK, &lp->lp_push_mdh);
        if (rc) {
                lnet_ping_buffer_decref(pbuf);
                CERROR("Can't bind push source MD: %d\n", rc);
                goto fail_error;
        }
+
        cpt = lnet_net_lock_current();
        /* Refcount for MD. */
        lnet_peer_addref_locked(lp);
        id.pid = LNET_PID_LUSTRE;
-       id.nid = lnet_peer_select_nid(lp);
+       if (lp->lp_disc_dst_nid != LNET_NID_ANY)
+               id.nid = lp->lp_disc_dst_nid;
+       else
+               id.nid = lp->lp_primary_nid;
        lnet_net_unlock(cpt);
 
-       if (id.nid == LNET_NID_ANY) {
-               rc = -EHOSTUNREACH;
-               goto fail_unlink;
-       }
-
        rc = LNetPut(lp->lp_disc_src_nid, lp->lp_push_mdh,
                     LNET_ACK_REQ, id, LNET_RESERVED_PORTAL,
                     LNET_PROTO_PING_MATCHBITS, 0, 0);
@@ -3123,6 +3532,7 @@ __must_hold(&lp->lp_lock)
         * scratch
         */
        lp->lp_disc_src_nid = LNET_NID_ANY;
+       lp->lp_disc_dst_nid = LNET_NID_ANY;
 
        if (rc)
                goto fail_unlink;
@@ -3166,53 +3576,6 @@ static void lnet_peer_discovery_error(struct lnet_peer *lp, int error)
 }
 
 /*
- * Mark the peer as discovered.
- */
-static int lnet_peer_discovered(struct lnet_peer *lp)
-__must_hold(&lp->lp_lock)
-{
-       lp->lp_state |= LNET_PEER_DISCOVERED;
-       lp->lp_state &= ~(LNET_PEER_DISCOVERING |
-                         LNET_PEER_REDISCOVER);
-
-       CDEBUG(D_NET, "peer %s\n", libcfs_nid2str(lp->lp_primary_nid));
-
-       return 0;
-}
-
-
-/*
- * Discovering this peer is taking too long. Cancel any Ping or Push
- * that discovery is waiting on by unlinking the relevant MDs. The
- * lnet_discovery_event_handler() will proceed from here and complete
- * the cleanup.
- */
-static void lnet_peer_cancel_discovery(struct lnet_peer *lp)
-{
-       struct lnet_handle_md ping_mdh;
-       struct lnet_handle_md push_mdh;
-
-       LNetInvalidateMDHandle(&ping_mdh);
-       LNetInvalidateMDHandle(&push_mdh);
-
-       spin_lock(&lp->lp_lock);
-       if (lp->lp_state & LNET_PEER_PING_SENT) {
-               ping_mdh = lp->lp_ping_mdh;
-               LNetInvalidateMDHandle(&lp->lp_ping_mdh);
-       }
-       if (lp->lp_state & LNET_PEER_PUSH_SENT) {
-               push_mdh = lp->lp_push_mdh;
-               LNetInvalidateMDHandle(&lp->lp_push_mdh);
-       }
-       spin_unlock(&lp->lp_lock);
-
-       if (!LNetMDHandleIsInvalid(ping_mdh))
-               LNetMDUnlink(ping_mdh);
-       if (!LNetMDHandleIsInvalid(push_mdh))
-               LNetMDUnlink(push_mdh);
-}
-
-/*
  * Wait for work to be queued or some other change that must be
  * attended to. Returns non-zero if the discovery thread should shut
  * down.
@@ -3368,7 +3731,10 @@ static int lnet_peer_discovery(void *arg)
                        CDEBUG(D_NET, "peer %s(%p) state %#x\n",
                                libcfs_nid2str(lp->lp_primary_nid), lp,
                                lp->lp_state);
-                       if (lp->lp_state & LNET_PEER_DATA_PRESENT)
+                       if (lp->lp_state & (LNET_PEER_MARK_DELETION |
+                                           LNET_PEER_MARK_DELETED))
+                               rc = lnet_peer_deletion(lp);
+                       else if (lp->lp_state & LNET_PEER_DATA_PRESENT)
                                rc = lnet_peer_data_present(lp);
                        else if (lp->lp_state & LNET_PEER_PING_FAILED)
                                rc = lnet_peer_ping_failed(lp);
@@ -3401,49 +3767,6 @@ static int lnet_peer_discovery(void *arg)
                        if (the_lnet.ln_dc_state == LNET_DC_STATE_STOPPING)
                                break;
 
-                       if (lp->lp_state & LNET_PEER_MARK_DELETION) {
-                               struct list_head rlist;
-                               struct lnet_route *route, *tmp;
-                               int sensitivity = lp->lp_health_sensitivity;
-
-                               INIT_LIST_HEAD(&rlist);
-
-                               /*
-                                * remove the peer from the discovery work
-                                * queue if it's on there in preparation
-                                * of deleting it.
-                                */
-                               if (!list_empty(&lp->lp_dc_list))
-                                       list_del(&lp->lp_dc_list);
-
-                               lnet_net_unlock(LNET_LOCK_EX);
-
-                               mutex_lock(&the_lnet.ln_api_mutex);
-
-                               lnet_net_lock(LNET_LOCK_EX);
-                               list_for_each_entry_safe(route, tmp,
-                                                        &lp->lp_routes,
-                                                        lr_gwlist)
-                                       lnet_move_route(route, NULL, &rlist);
-                               lnet_net_unlock(LNET_LOCK_EX);
-
-                               /* delete the peer */
-                               lnet_peer_del(lp);
-
-                               list_for_each_entry_safe(route, tmp,
-                                                        &rlist, lr_list) {
-                                       /* re-add these routes */
-                                       lnet_add_route(route->lr_net,
-                                                      route->lr_hops,
-                                                      route->lr_nid,
-                                                      route->lr_priority,
-                                                      sensitivity);
-                                       LIBCFS_FREE(route, sizeof(*route));
-                               }
-                               mutex_unlock(&the_lnet.ln_api_mutex);
-
-                               lnet_net_lock(LNET_LOCK_EX);
-                       }
                }
 
                lnet_net_unlock(LNET_LOCK_EX);
@@ -3570,7 +3893,7 @@ lnet_debug_peer(lnet_nid_t nid)
                aliveness = (lnet_is_peer_ni_alive(lp)) ? "up" : "down";
 
        CDEBUG(D_WARNING, "%-24s %4d %5s %5d %5d %5d %5d %5d %ld\n",
-              libcfs_nid2str(lp->lpni_nid), atomic_read(&lp->lpni_refcount),
+              libcfs_nid2str(lp->lpni_nid), kref_read(&lp->lpni_kref),
               aliveness, lp->lpni_net->net_tunables.lct_peer_tx_credits,
               lp->lpni_rtrcredits, lp->lpni_minrtrcredits,
               lp->lpni_txcredits, lp->lpni_mintxcredits, lp->lpni_txqnob);
@@ -3626,7 +3949,7 @@ int lnet_get_peer_ni_info(__u32 peer_index, __u64 *nid,
                                         lnet_is_peer_ni_alive(lp) ? "up" : "down");
 
                        *nid = lp->lpni_nid;
-                       *refcount = atomic_read(&lp->lpni_refcount);
+                       *refcount = kref_read(&lp->lpni_kref);
                        *ni_peer_tx_credits =
                                lp->lpni_net->net_tunables.lct_peer_tx_credits;
                        *peer_tx_credits = lp->lpni_txcredits;
@@ -3712,7 +4035,7 @@ int lnet_get_peer_info(struct lnet_ioctl_peer_cfg *cfg, void __user *bulk)
                        snprintf(lpni_info->cr_aliveness, LNET_MAX_STR_LEN,
                                lnet_is_peer_ni_alive(lpni) ? "up" : "down");
 
-               lpni_info->cr_refcount = atomic_read(&lpni->lpni_refcount);
+               lpni_info->cr_refcount = kref_read(&lpni->lpni_kref);
                lpni_info->cr_ni_peer_tx_credits = (lpni->lpni_net != NULL) ?
                        lpni->lpni_net->net_tunables.lct_peer_tx_credits : 0;
                lpni_info->cr_peer_tx_credits = lpni->lpni_txcredits;
@@ -3748,6 +4071,8 @@ int lnet_get_peer_info(struct lnet_ioctl_peer_cfg *cfg, void __user *bulk)
                  atomic_read(&lpni->lpni_hstats.hlt_remote_error);
                lpni_hstats->hlpni_health_value =
                  atomic_read(&lpni->lpni_healthv);
+               lpni_hstats->hlpni_ping_count = lpni->lpni_ping_count;
+               lpni_hstats->hlpni_next_ping = lpni->lpni_next_ping;
                if (copy_to_user(bulk, lpni_hstats, sizeof(*lpni_hstats)))
                        goto out_free_hstats;
                bulk += sizeof(*lpni_hstats);
@@ -3768,21 +4093,55 @@ out:
        return rc;
 }
 
+/* must hold net_lock/0 */
 void
-lnet_peer_ni_add_to_recoveryq_locked(struct lnet_peer_ni *lpni)
+lnet_peer_ni_add_to_recoveryq_locked(struct lnet_peer_ni *lpni,
+                                    struct list_head *recovery_queue,
+                                    time64_t now)
 {
        /* the mt could've shutdown and cleaned up the queues */
        if (the_lnet.ln_mt_state != LNET_MT_STATE_RUNNING)
                return;
 
-       if (list_empty(&lpni->lpni_recovery) &&
-           atomic_read(&lpni->lpni_healthv) < LNET_MAX_HEALTH_VALUE) {
-               CDEBUG(D_NET, "lpni %s added to recovery queue. Health = %d\n",
-                       libcfs_nid2str(lpni->lpni_nid),
-                       atomic_read(&lpni->lpni_healthv));
-               list_add_tail(&lpni->lpni_recovery, &the_lnet.ln_mt_peerNIRecovq);
-               lnet_peer_ni_addref_locked(lpni);
+       if (!list_empty(&lpni->lpni_recovery))
+               return;
+
+       if (atomic_read(&lpni->lpni_healthv) == LNET_MAX_HEALTH_VALUE)
+               return;
+
+       if (!lpni->lpni_last_alive) {
+               CDEBUG(D_NET,
+                      "lpni %s(%p) not eligible for recovery last alive %lld\n",
+                      libcfs_nid2str(lpni->lpni_nid), lpni,
+                      lpni->lpni_last_alive);
+               return;
+       }
+
+       if (lnet_recovery_limit &&
+           now > lpni->lpni_last_alive + lnet_recovery_limit) {
+               CDEBUG(D_NET, "lpni %s aged out last alive %lld\n",
+                      libcfs_nid2str(lpni->lpni_nid),
+                      lpni->lpni_last_alive);
+               /* Reset the ping count so that if this peer NI is added back to
+                * the recovery queue we will send the first ping right away.
+                */
+               lpni->lpni_ping_count = 0;
+               return;
        }
+
+       /* This peer NI is going on the recovery queue, so take a ref on it */
+       lnet_peer_ni_addref_locked(lpni);
+
+       lnet_peer_ni_set_next_ping(lpni, now);
+
+       CDEBUG(D_NET, "%s added to recovery queue. ping count: %u next ping: %lld last alive: %lld health: %d\n",
+              libcfs_nid2str(lpni->lpni_nid),
+              lpni->lpni_ping_count,
+              lpni->lpni_next_ping,
+              lpni->lpni_last_alive,
+              atomic_read(&lpni->lpni_healthv));
+
+       list_add_tail(&lpni->lpni_recovery, recovery_queue);
 }
 
 /* Call with the ln_api_mutex held */
@@ -3795,10 +4154,13 @@ lnet_peer_ni_set_healthv(lnet_nid_t nid, int value, bool all)
        struct lnet_peer_ni *lpni;
        int lncpt;
        int cpt;
+       time64_t now;
 
        if (the_lnet.ln_state != LNET_STATE_RUNNING)
                return;
 
+       now = ktime_get_seconds();
+
        if (!all) {
                lnet_net_lock(LNET_LOCK_EX);
                lpni = lnet_find_peer_ni_locked(nid);
@@ -3806,8 +4168,9 @@ lnet_peer_ni_set_healthv(lnet_nid_t nid, int value, bool all)
                        lnet_net_unlock(LNET_LOCK_EX);
                        return;
                }
-               atomic_set(&lpni->lpni_healthv, value);
-               lnet_peer_ni_add_to_recoveryq_locked(lpni);
+               lnet_set_lpni_healthv_locked(lpni, value);
+               lnet_peer_ni_add_to_recoveryq_locked(lpni,
+                                            &the_lnet.ln_mt_peerNIRecovq, now);
                lnet_peer_ni_decref_locked(lpni);
                lnet_net_unlock(LNET_LOCK_EX);
                return;
@@ -3816,8 +4179,8 @@ lnet_peer_ni_set_healthv(lnet_nid_t nid, int value, bool all)
        lncpt = cfs_percpt_number(the_lnet.ln_peer_tables);
 
        /*
-        * Walk all the peers and reset the healhv for each one to the
-        * maximum value.
+        * Walk all the peers and reset the health value for each one to the
+        * specified value.
         */
        lnet_net_lock(LNET_LOCK_EX);
        for (cpt = 0; cpt < lncpt; cpt++) {
@@ -3826,8 +4189,10 @@ lnet_peer_ni_set_healthv(lnet_nid_t nid, int value, bool all)
                        list_for_each_entry(lpn, &lp->lp_peer_nets, lpn_peer_nets) {
                                list_for_each_entry(lpni, &lpn->lpn_peer_nis,
                                                    lpni_peer_nis) {
-                                       atomic_set(&lpni->lpni_healthv, value);
-                                       lnet_peer_ni_add_to_recoveryq_locked(lpni);
+                                       lnet_set_lpni_healthv_locked(lpni,
+                                                                    value);
+                                       lnet_peer_ni_add_to_recoveryq_locked(lpni,
+                                            &the_lnet.ln_mt_peerNIRecovq, now);
                                }
                        }
                }