Whamcloud - gitweb
LU-13895 lnet: Prevent discovery on deleted peer
[fs/lustre-release.git] / lnet / lnet / peer.c
index b745eb3..e3eb262 100644 (file)
@@ -40,6 +40,7 @@
 #endif
 #include <linux/uaccess.h>
 
+#include <lnet/udsp.h>
 #include <lnet/lib-lnet.h>
 #include <uapi/linux/lnet/lnet-dlc.h>
 
@@ -166,7 +167,10 @@ 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);
+       atomic_set(&lpni->lpni_refcount, 1);
+       lpni->lpni_sel_priority = LNET_MAX_SELECTION_PRIORITY;
 
        spin_lock_init(&lpni->lpni_lock);
 
@@ -194,7 +198,7 @@ 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 +220,7 @@ 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));
 
@@ -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)
 {
@@ -1193,6 +1349,11 @@ LNetPrimaryNID(lnet_nid_t nid)
        lp = lpni->lpni_peer_net->lpn_peer;
 
        while (!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;
@@ -1231,9 +1392,9 @@ 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 +1403,8 @@ 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 +1415,7 @@ 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. */
@@ -1273,6 +1435,7 @@ lnet_peer_attach_peer_ni(struct lnet_peer *lp,
 
        /* 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);
                lnet_peer_addref_locked(lp);
@@ -1301,11 +1464,24 @@ 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;
 }
@@ -1426,17 +1602,16 @@ 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 +1623,18 @@ 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 +1657,7 @@ 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),
@@ -1706,19 +1880,28 @@ 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 *
@@ -2032,13 +2215,17 @@ 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",
@@ -2798,6 +2985,72 @@ 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(&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.
  */
@@ -3060,6 +3313,23 @@ __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 +3343,12 @@ __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;
        }
 
@@ -3090,7 +3366,7 @@ __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;
 
@@ -3166,53 +3442,6 @@ 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 +3597,10 @@ 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 +3633,6 @@ 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);