Whamcloud - gitweb
LU-7734 lnet: implement Peer Discovery
[fs/lustre-release.git] / lnet / lnet / peer.c
index 7fe9dd1..8278273 100644 (file)
@@ -42,6 +42,11 @@ module_param(lnet_peer_discovery_enabled, uint, 0644);
 MODULE_PARM_DESC(lnet_peer_discovery_enabled,
                "Explicitly enable/disable peer discovery");
 
+/* Value indicating that recovery needs to re-check a peer immediately. */
+#define LNET_REDISCOVER_PEER   (1)
+
+static int lnet_peer_queue_for_discovery(struct lnet_peer *lp);
+
 static void
 lnet_peer_remove_from_remote_list(struct lnet_peer_ni *lpni)
 {
@@ -261,6 +266,10 @@ lnet_destroy_peer_locked(struct lnet_peer *lp)
        LASSERT(atomic_read(&lp->lp_refcount) == 0);
        LASSERT(list_empty(&lp->lp_peer_nets));
        LASSERT(list_empty(&lp->lp_peer_list));
+       LASSERT(list_empty(&lp->lp_dc_list));
+
+       if (lp->lp_data)
+               lnet_ping_buffer_decref(lp->lp_data);
 
        LIBCFS_FREE(lp, sizeof(*lp));
 }
@@ -301,10 +310,19 @@ lnet_peer_detach_peer_ni_locked(struct lnet_peer_ni *lpni)
        /*
         * If there are no more peer nets, make the peer unfindable
         * via the peer_tables.
+        *
+        * Otherwise, if the peer is DISCOVERED, tell discovery to
+        * take another look at it. This is a no-op if discovery for
+        * this peer did the detaching.
         */
        if (list_empty(&lp->lp_peer_nets)) {
                list_del_init(&lp->lp_peer_list);
                ptable->pt_peers--;
+       } else if (the_lnet.ln_dc_state != LNET_DC_STATE_RUNNING) {
+               /* Discovery isn't running, nothing to do here. */
+       } else if (lp->lp_state & LNET_PEER_DISCOVERED) {
+               lnet_peer_queue_for_discovery(lp);
+               wake_up(&the_lnet.ln_dc_waitq);
        }
        CDEBUG(D_NET, "peer %s NID %s\n",
                libcfs_nid2str(lp->lp_primary_nid),
@@ -600,6 +618,25 @@ lnet_find_peer_ni_locked(lnet_nid_t nid)
        return lpni;
 }
 
+struct lnet_peer *
+lnet_find_peer(lnet_nid_t nid)
+{
+       struct lnet_peer_ni *lpni;
+       struct lnet_peer *lp = NULL;
+       int cpt;
+
+       cpt = lnet_net_lock_current();
+       lpni = lnet_find_peer_ni_locked(nid);
+       if (lpni) {
+               lp = lpni->lpni_peer_net->lpn_peer;
+               lnet_peer_addref_locked(lp);
+               lnet_peer_ni_decref_locked(lpni);
+       }
+       lnet_net_unlock(cpt);
+
+       return lp;
+}
+
 struct lnet_peer_ni *
 lnet_get_peer_ni_idx_locked(int idx, struct lnet_peer_net **lpn,
                            struct lnet_peer **lp)
@@ -951,6 +988,7 @@ lnet_peer_primary_nid(lnet_nid_t nid)
 lnet_nid_t
 LNetPrimaryNID(lnet_nid_t nid)
 {
+       struct lnet_peer *lp;
        struct lnet_peer_ni *lpni;
        lnet_nid_t primary_nid = nid;
        int rc = 0;
@@ -962,7 +1000,15 @@ LNetPrimaryNID(lnet_nid_t nid)
                rc = PTR_ERR(lpni);
                goto out_unlock;
        }
-       primary_nid = lpni->lpni_peer_net->lpn_peer->lp_primary_nid;
+       lp = lpni->lpni_peer_net->lpn_peer;
+       while (!lnet_peer_is_uptodate(lp)) {
+               rc = lnet_discover_peer_locked(lpni, cpt);
+               if (rc)
+                       goto out_decref;
+               lp = lpni->lpni_peer_net->lpn_peer;
+       }
+       primary_nid = lp->lp_primary_nid;
+out_decref:
        lnet_peer_ni_decref_locked(lpni);
 out_unlock:
        lnet_net_unlock(cpt);
@@ -1240,6 +1286,29 @@ out:
 }
 
 /*
+ * Update the primary NID of a peer, if possible.
+ *
+ * Call with the lnet_api_mutex held.
+ */
+static int
+lnet_peer_set_primary_nid(struct lnet_peer *lp, lnet_nid_t nid, unsigned flags)
+{
+       lnet_nid_t old = lp->lp_primary_nid;
+       int rc = 0;
+
+       if (lp->lp_primary_nid == nid)
+               goto out;
+       rc = lnet_peer_add_nid(lp, nid, flags);
+       if (rc)
+               goto out;
+       lp->lp_primary_nid = nid;
+out:
+       CDEBUG(D_NET, "peer %s NID %s: %d\n",
+              libcfs_nid2str(old), libcfs_nid2str(nid), rc);
+       return rc;
+}
+
+/*
  * lpni creation initiated due to traffic either sending or receiving.
  */
 static int
@@ -1548,7 +1617,9 @@ lnet_peer_is_uptodate(struct lnet_peer *lp)
        bool rc;
 
        spin_lock(&lp->lp_lock);
-       if (lp->lp_state & LNET_PEER_DISCOVERING) {
+       if (lnet_peer_needs_push(lp)) {
+               rc = false;
+       } else if (lp->lp_state & LNET_PEER_DISCOVERING) {
                rc = false;
        } else if (lp->lp_state & LNET_PEER_DISCOVERED) {
                if (lp->lp_state & LNET_PEER_NIDS_UPTODATE)
@@ -1592,6 +1663,9 @@ static int lnet_peer_queue_for_discovery(struct lnet_peer *lp)
                rc = -EALREADY;
        }
 
+       CDEBUG(D_NET, "Queue peer %s: %d\n",
+              libcfs_nid2str(lp->lp_primary_nid), rc);
+
        return rc;
 }
 
@@ -1601,7 +1675,11 @@ static int lnet_peer_queue_for_discovery(struct lnet_peer *lp)
  */
 static void lnet_peer_discovery_complete(struct lnet_peer *lp)
 {
+       CDEBUG(D_NET, "Dequeue peer %s\n",
+              libcfs_nid2str(lp->lp_primary_nid));
+
        spin_lock(&lp->lp_lock);
+       LASSERT(lp->lp_state & LNET_PEER_QUEUED);
        lp->lp_state &= ~LNET_PEER_QUEUED;
        spin_unlock(&lp->lp_lock);
        list_del_init(&lp->lp_dc_list);
@@ -1610,6 +1688,202 @@ static void lnet_peer_discovery_complete(struct lnet_peer *lp)
 }
 
 /*
+ * Handle inbound push.
+ * Like any event handler, called with lnet_res_lock/CPT held.
+ */
+void lnet_peer_push_event(struct lnet_event *ev)
+{
+       struct lnet_ping_buffer *pbuf = ev->md.user_ptr;
+       struct lnet_peer *lp;
+
+       /* lnet_find_peer() adds a refcount */
+       lp = lnet_find_peer(ev->source.nid);
+       if (!lp) {
+               CERROR("Push Put from unknown %s (source %s)\n",
+                      libcfs_nid2str(ev->initiator.nid),
+                      libcfs_nid2str(ev->source.nid));
+               return;
+       }
+
+       /* Ensure peer state remains consistent while we modify it. */
+       spin_lock(&lp->lp_lock);
+
+       /*
+        * If some kind of error happened the contents of the message
+        * cannot be used. Clear the NIDS_UPTODATE and set the
+        * PING_REQUIRED flag to trigger a ping.
+        */
+       if (ev->status) {
+               lp->lp_state &= ~LNET_PEER_NIDS_UPTODATE;
+               lp->lp_state |= LNET_PEER_PING_REQUIRED;
+               CDEBUG(D_NET, "Push Put error %d from %s (source %s)\n",
+                      ev->status,
+                      libcfs_nid2str(lp->lp_primary_nid),
+                      libcfs_nid2str(ev->source.nid));
+               goto out;
+       }
+
+       /*
+        * A push with invalid or corrupted info. Clear the UPTODATE
+        * flag to trigger a ping.
+        */
+       if (lnet_ping_info_validate(&pbuf->pb_info)) {
+               lp->lp_state &= ~LNET_PEER_NIDS_UPTODATE;
+               lp->lp_state |= LNET_PEER_PING_REQUIRED;
+               CDEBUG(D_NET, "Corrupted Push from %s\n",
+                      libcfs_nid2str(lp->lp_primary_nid));
+               goto out;
+       }
+
+       /*
+        * Make sure we'll allocate the correct size ping buffer when
+        * pinging the peer.
+        */
+       if (lp->lp_data_nnis < pbuf->pb_info.pi_nnis)
+               lp->lp_data_nnis = pbuf->pb_info.pi_nnis;
+
+       /*
+        * A non-Multi-Rail peer is not supposed to be capable of
+        * sending a push.
+        */
+       if (!(pbuf->pb_info.pi_features & LNET_PING_FEAT_MULTI_RAIL)) {
+               CERROR("Push from non-Multi-Rail peer %s dropped\n",
+                      libcfs_nid2str(lp->lp_primary_nid));
+               goto out;
+       }
+
+       /*
+        * Set the MULTIRAIL flag. Complain if the peer was DLC
+        * configured without it. This is the one place where
+        * discovery will override DLC.
+        */
+       if (!(lp->lp_state & LNET_PEER_MULTI_RAIL)) {
+               if (lp->lp_state & LNET_PEER_CONFIGURED) {
+                       CERROR("Push says %s is Multi-Rail, DLC says not\n",
+                              libcfs_nid2str(lp->lp_primary_nid));
+               }
+               lp->lp_state |= LNET_PEER_MULTI_RAIL;
+               lnet_peer_clr_non_mr_pref_nids(lp);
+       }
+
+       /*
+        * Check for truncation of the Put message. Clear the
+        * NIDS_UPTODATE flag and set PING_REQUIRED to trigger a ping,
+        * and tell discovery to allocate a bigger buffer.
+        */
+       if (pbuf->pb_nnis < pbuf->pb_info.pi_nnis) {
+               if (the_lnet.ln_push_target_nnis < pbuf->pb_info.pi_nnis)
+                       the_lnet.ln_push_target_nnis = pbuf->pb_info.pi_nnis;
+               lp->lp_state &= ~LNET_PEER_NIDS_UPTODATE;
+               lp->lp_state |= LNET_PEER_PING_REQUIRED;
+               CDEBUG(D_NET, "Truncated Push from %s (%d nids)\n",
+                      libcfs_nid2str(lp->lp_primary_nid),
+                      pbuf->pb_info.pi_nnis);
+               goto out;
+       }
+
+       /*
+        * Check whether the Put data is stale. Stale data can just be
+        * dropped.
+        */
+       if (pbuf->pb_info.pi_nnis > 1 &&
+           lp->lp_primary_nid == pbuf->pb_info.pi_ni[1].ns_nid &&
+           LNET_PING_BUFFER_SEQNO(pbuf) < lp->lp_peer_seqno) {
+               CDEBUG(D_NET, "Stale Push from %s: got %u have %u\n",
+                      libcfs_nid2str(lp->lp_primary_nid),
+                      LNET_PING_BUFFER_SEQNO(pbuf),
+                      lp->lp_peer_seqno);
+               goto out;
+       }
+
+       /*
+        * Check whether the Put data is new, in which case we clear
+        * the UPTODATE flag and prepare to process it.
+        *
+        * If the Put data is current, and the peer is UPTODATE then
+        * we assome everything is all right and drop the data as
+        * stale.
+        */
+       if (LNET_PING_BUFFER_SEQNO(pbuf) > lp->lp_peer_seqno) {
+               lp->lp_peer_seqno = LNET_PING_BUFFER_SEQNO(pbuf);
+               lp->lp_state &= ~LNET_PEER_NIDS_UPTODATE;
+       } else if (lp->lp_state & LNET_PEER_NIDS_UPTODATE) {
+               CDEBUG(D_NET, "Stale Push from %s: got %u have %u\n",
+                      libcfs_nid2str(lp->lp_primary_nid),
+                      LNET_PING_BUFFER_SEQNO(pbuf),
+                      lp->lp_peer_seqno);
+               goto out;
+       }
+
+       /*
+        * If there is data present that hasn't been processed yet,
+        * we'll replace it if the Put contained newer data and it
+        * fits. We're racing with a Ping or earlier Push in this
+        * case.
+        */
+       if (lp->lp_state & LNET_PEER_DATA_PRESENT) {
+               if (LNET_PING_BUFFER_SEQNO(pbuf) >
+                       LNET_PING_BUFFER_SEQNO(lp->lp_data) &&
+                   pbuf->pb_info.pi_nnis <= lp->lp_data->pb_nnis) {
+                       memcpy(&lp->lp_data->pb_info, &pbuf->pb_info,
+                              LNET_PING_INFO_SIZE(pbuf->pb_info.pi_nnis));
+                       CDEBUG(D_NET, "Ping/Push race from %s: %u vs %u\n",
+                             libcfs_nid2str(lp->lp_primary_nid),
+                             LNET_PING_BUFFER_SEQNO(pbuf),
+                             LNET_PING_BUFFER_SEQNO(lp->lp_data));
+               }
+               goto out;
+       }
+
+       /*
+        * Allocate a buffer to copy the data. On a failure we drop
+        * the Push and set PING_REQUIRED to force the discovery
+        * thread to fix the problem by pinging the peer.
+        */
+       lp->lp_data = lnet_ping_buffer_alloc(lp->lp_data_nnis, GFP_ATOMIC);
+       if (!lp->lp_data) {
+               lp->lp_state |= LNET_PEER_PING_REQUIRED;
+               CDEBUG(D_NET, "Cannot allocate Push buffer for %s %u\n",
+                      libcfs_nid2str(lp->lp_primary_nid),
+                      LNET_PING_BUFFER_SEQNO(pbuf));
+               goto out;
+       }
+
+       /* Success */
+       memcpy(&lp->lp_data->pb_info, &pbuf->pb_info,
+              LNET_PING_INFO_SIZE(pbuf->pb_info.pi_nnis));
+       lp->lp_state |= LNET_PEER_DATA_PRESENT;
+       CDEBUG(D_NET, "Received Push %s %u\n",
+              libcfs_nid2str(lp->lp_primary_nid),
+              LNET_PING_BUFFER_SEQNO(pbuf));
+
+out:
+       /*
+        * Queue the peer for discovery, and wake the discovery thread
+        * if the peer was already queued, because its status changed.
+        */
+       spin_unlock(&lp->lp_lock);
+       lnet_net_lock(LNET_LOCK_EX);
+       if (lnet_peer_queue_for_discovery(lp))
+               wake_up(&the_lnet.ln_dc_waitq);
+       /* Drop refcount from lookup */
+       lnet_peer_decref_locked(lp);
+       lnet_net_unlock(LNET_LOCK_EX);
+}
+
+/*
+ * Clear the discovery error state, unless we're already discovering
+ * this peer, in which case the error is current.
+ */
+static void lnet_peer_clear_discovery_error(struct lnet_peer *lp)
+{
+       spin_lock(&lp->lp_lock);
+       if (!(lp->lp_state & LNET_PEER_DISCOVERING))
+               lp->lp_dc_error = 0;
+       spin_unlock(&lp->lp_lock);
+}
+
+/*
  * Peer discovery slow path. The ln_api_mutex is held on entry, and
  * dropped/retaken within this function. An lnet_peer_ni is passed in
  * because discovery could tear down an lnet_peer.
@@ -1624,15 +1898,21 @@ lnet_discover_peer_locked(struct lnet_peer_ni *lpni, int cpt)
 again:
        lnet_net_unlock(cpt);
        lnet_net_lock(LNET_LOCK_EX);
+       lp = lpni->lpni_peer_net->lpn_peer;
+       lnet_peer_clear_discovery_error(lp);
 
-       /* We're willing to be interrupted. */
+       /*
+        * We're willing to be interrupted. The lpni can become a
+        * zombie if we race with DLC, so we must check for that.
+        */
        for (;;) {
-               lp = lpni->lpni_peer_net->lpn_peer;
                prepare_to_wait(&lp->lp_dc_waitq, &wait, TASK_INTERRUPTIBLE);
                if (signal_pending(current))
                        break;
                if (the_lnet.ln_dc_state != LNET_DC_STATE_RUNNING)
                        break;
+               if (lp->lp_dc_error)
+                       break;
                if (lnet_peer_is_uptodate(lp))
                        break;
                lnet_peer_queue_for_discovery(lp);
@@ -1642,7 +1922,8 @@ again:
                finish_wait(&lp->lp_dc_waitq, &wait);
                lnet_net_lock(LNET_LOCK_EX);
                lnet_peer_decref_locked(lp);
-               /* Do not use lp beyond this point. */
+               /* Peer may have changed */
+               lp = lpni->lpni_peer_net->lpn_peer;
        }
        finish_wait(&lp->lp_dc_waitq, &wait);
 
@@ -1653,9 +1934,189 @@ again:
                rc = -EINTR;
        else if (the_lnet.ln_dc_state != LNET_DC_STATE_RUNNING)
                rc = -ESHUTDOWN;
+       else if (lp->lp_dc_error)
+               rc = lp->lp_dc_error;
        else if (!lnet_peer_is_uptodate(lp))
                goto again;
 
+       CDEBUG(D_NET, "peer %s NID %s: %d\n",
+              (lp ? libcfs_nid2str(lp->lp_primary_nid) : "(none)"),
+              libcfs_nid2str(lpni->lpni_nid), rc);
+
+       return rc;
+}
+
+/* Handle an incoming ack for a push. */
+static void
+lnet_discovery_event_ack(struct lnet_peer *lp, struct lnet_event *ev)
+{
+       struct lnet_ping_buffer *pbuf;
+
+       pbuf = LNET_PING_INFO_TO_BUFFER(ev->md.start);
+       spin_lock(&lp->lp_lock);
+       lp->lp_state &= ~LNET_PEER_PUSH_SENT;
+       lp->lp_push_error = ev->status;
+       if (ev->status)
+               lp->lp_state |= LNET_PEER_PUSH_FAILED;
+       else
+               lp->lp_node_seqno = LNET_PING_BUFFER_SEQNO(pbuf);
+       spin_unlock(&lp->lp_lock);
+
+       CDEBUG(D_NET, "peer %s ev->status %d\n",
+              libcfs_nid2str(lp->lp_primary_nid), ev->status);
+}
+
+/* Handle a Reply message. This is the reply to a Ping message. */
+static void
+lnet_discovery_event_reply(struct lnet_peer *lp, struct lnet_event *ev)
+{
+       struct lnet_ping_buffer *pbuf;
+       int rc;
+
+       spin_lock(&lp->lp_lock);
+
+       /*
+        * If some kind of error happened the contents of message
+        * cannot be used. Set PING_FAILED to trigger a retry.
+        */
+       if (ev->status) {
+               lp->lp_state |= LNET_PEER_PING_FAILED;
+               lp->lp_ping_error = ev->status;
+               CDEBUG(D_NET, "Ping Reply error %d from %s (source %s)\n",
+                      ev->status,
+                      libcfs_nid2str(lp->lp_primary_nid),
+                      libcfs_nid2str(ev->source.nid));
+               goto out;
+       }
+
+       pbuf = LNET_PING_INFO_TO_BUFFER(ev->md.start);
+       if (pbuf->pb_info.pi_magic == __swab32(LNET_PROTO_PING_MAGIC))
+               lnet_swap_pinginfo(pbuf);
+
+       /*
+        * A reply with invalid or corrupted info. Set PING_FAILED to
+        * trigger a retry.
+        */
+       rc = lnet_ping_info_validate(&pbuf->pb_info);
+       if (rc) {
+               lp->lp_state |= LNET_PEER_PING_FAILED;
+               lp->lp_ping_error = 0;
+               CDEBUG(D_NET, "Corrupted Ping Reply from %s: %d\n",
+                      libcfs_nid2str(lp->lp_primary_nid), rc);
+               goto out;
+       }
+
+       /*
+        * Update the MULTI_RAIL flag based on the reply. If the peer
+        * was configured with DLC then the setting should match what
+        * DLC put in. Once MULTIRAIL has been set it is not expected
+        * to be unset.
+        */
+       if (pbuf->pb_info.pi_features & LNET_PING_FEAT_MULTI_RAIL) {
+               if (lp->lp_state & LNET_PEER_MULTI_RAIL) {
+                       /* Everything's fine */
+               } else if (lp->lp_state & LNET_PEER_CONFIGURED) {
+                       CWARN("Reply says %s is Multi-Rail, DLC says not\n",
+                             libcfs_nid2str(lp->lp_primary_nid));
+               }
+               lp->lp_state |= LNET_PEER_MULTI_RAIL;
+               lnet_peer_clr_non_mr_pref_nids(lp);
+       } else if (lp->lp_state & LNET_PEER_MULTI_RAIL) {
+               if (lp->lp_state & LNET_PEER_CONFIGURED) {
+                       CWARN("DLC says %s is Multi-Rail, Reply says not\n",
+                             libcfs_nid2str(lp->lp_primary_nid));
+               } else {
+                       CERROR("Multi-Rail state vanished from %s\n",
+                              libcfs_nid2str(lp->lp_primary_nid));
+               }
+       }
+
+       /*
+        * Make sure we'll allocate the correct size ping buffer when
+        * pinging the peer.
+        */
+       if (lp->lp_data_nnis < pbuf->pb_info.pi_nnis)
+               lp->lp_data_nnis = pbuf->pb_info.pi_nnis;
+
+       /*
+        * Check for truncation of the Reply. Clear PING_SENT and set
+        * PING_FAILED to trigger a retry.
+        */
+       if (pbuf->pb_nnis < pbuf->pb_info.pi_nnis) {
+               if (the_lnet.ln_push_target_nnis < pbuf->pb_info.pi_nnis)
+                       the_lnet.ln_push_target_nnis = pbuf->pb_info.pi_nnis;
+               lp->lp_state |= LNET_PEER_PING_FAILED;
+               lp->lp_ping_error = 0;
+               CDEBUG(D_NET, "Truncated Reply from %s (%d nids)\n",
+                      libcfs_nid2str(lp->lp_primary_nid),
+                      pbuf->pb_info.pi_nnis);
+               goto out;
+       }
+
+       /*
+        * Check the sequence numbers in the reply. These are only
+        * available if the reply came from a Multi-Rail peer.
+        */
+       if (pbuf->pb_info.pi_features & LNET_PING_FEAT_MULTI_RAIL &&
+           pbuf->pb_info.pi_nnis > 1 &&
+           lp->lp_primary_nid == pbuf->pb_info.pi_ni[1].ns_nid) {
+               if (LNET_PING_BUFFER_SEQNO(pbuf) < lp->lp_peer_seqno) {
+                       CDEBUG(D_NET, "Stale Reply from %s: got %u have %u\n",
+                               libcfs_nid2str(lp->lp_primary_nid),
+                               LNET_PING_BUFFER_SEQNO(pbuf),
+                               lp->lp_peer_seqno);
+                       goto out;
+               }
+
+               if (LNET_PING_BUFFER_SEQNO(pbuf) > lp->lp_peer_seqno)
+                       lp->lp_peer_seqno = LNET_PING_BUFFER_SEQNO(pbuf);
+       }
+
+       /* We're happy with the state of the data in the buffer. */
+       CDEBUG(D_NET, "peer %s data present %u\n",
+              libcfs_nid2str(lp->lp_primary_nid), lp->lp_peer_seqno);
+       if (lp->lp_state & LNET_PEER_DATA_PRESENT)
+               lnet_ping_buffer_decref(lp->lp_data);
+       else
+               lp->lp_state |= LNET_PEER_DATA_PRESENT;
+       lnet_ping_buffer_addref(pbuf);
+       lp->lp_data = pbuf;
+out:
+       lp->lp_state &= ~LNET_PEER_PING_SENT;
+       spin_unlock(&lp->lp_lock);
+}
+
+/*
+ * Send event handling. Only matters for error cases, where we clean
+ * up state on the peer and peer_ni that would otherwise be updated in
+ * the REPLY event handler for a successful Ping, and the ACK event
+ * handler for a successful Push.
+ */
+static int
+lnet_discovery_event_send(struct lnet_peer *lp, struct lnet_event *ev)
+{
+       int rc = 0;
+
+       if (!ev->status)
+               goto out;
+
+       LASSERT(lp->lp_state & LNET_PEER_QUEUED);
+       spin_lock(&lp->lp_lock);
+       if (ev->msg_type == LNET_MSG_GET) {
+               lp->lp_state &= ~LNET_PEER_PING_SENT;
+               lp->lp_state |= LNET_PEER_PING_FAILED;
+               lp->lp_ping_error = ev->status;
+       } else { /* ev->msg_type == LNET_MSG_PUT */
+               lp->lp_state &= ~LNET_PEER_PUSH_SENT;
+               lp->lp_state |= LNET_PEER_PUSH_FAILED;
+               lp->lp_push_error = ev->status;
+       }
+       spin_unlock(&lp->lp_lock);
+       rc = LNET_REDISCOVER_PEER;
+out:
+       CDEBUG(D_NET, "%s Send to %s: %d\n",
+               (ev->msg_type == LNET_MSG_GET ? "Ping" : "Push"),
+               libcfs_nid2str(ev->target.nid), rc);
        return rc;
 }
 
@@ -1667,7 +2128,605 @@ again:
  */
 static void lnet_discovery_event_handler(lnet_event_t *event)
 {
-       wake_up(&the_lnet.ln_dc_waitq);
+       struct lnet_peer *lp = event->md.user_ptr;
+       struct lnet_ping_buffer *pbuf;
+       int rc;
+
+       /* discovery needs to take another look */
+       rc = LNET_REDISCOVER_PEER;
+
+       switch (event->type) {
+       case LNET_EVENT_ACK:
+               lnet_discovery_event_ack(lp, event);
+               break;
+       case LNET_EVENT_REPLY:
+               lnet_discovery_event_reply(lp, event);
+               break;
+       case LNET_EVENT_SEND:
+               /* Only send failure triggers a retry. */
+               rc = lnet_discovery_event_send(lp, event);
+               break;
+       case LNET_EVENT_UNLINK:
+               /* Valid event, nothing to do here. */
+               break;
+       default:
+               /* Invalid events. */
+               LBUG();
+       }
+       lnet_net_lock(LNET_LOCK_EX);
+       if (event->unlinked) {
+               pbuf = LNET_PING_INFO_TO_BUFFER(event->md.start);
+               lnet_ping_buffer_decref(pbuf);
+               lnet_peer_decref_locked(lp);
+       }
+       if (rc == LNET_REDISCOVER_PEER) {
+               list_move_tail(&lp->lp_dc_list, &the_lnet.ln_dc_request);
+               wake_up(&the_lnet.ln_dc_waitq);
+       }
+       lnet_net_unlock(LNET_LOCK_EX);
+}
+
+/*
+ * Build a peer from incoming data.
+ *
+ * The NIDs in the incoming data are supposed to be structured as follows:
+ *  - loopback
+ *  - primary NID
+ *  - other NIDs in same net
+ *  - NIDs in second net
+ *  - NIDs in third net
+ *  - ...
+ * This due to the way the list of NIDs in the data is created.
+ *
+ * Note that this function will mark the peer uptodate unless an
+ * ENOMEM is encontered. All other errors are due to a conflict
+ * between the DLC configuration and what discovery sees. We treat DLC
+ * as binding, and therefore set the NIDS_UPTODATE flag to prevent the
+ * peer from becoming stuck in discovery.
+ */
+static int lnet_peer_merge_data(struct lnet_peer *lp,
+                               struct lnet_ping_buffer *pbuf)
+{
+       struct lnet_peer_ni *lpni;
+       lnet_nid_t *curnis = NULL;
+       lnet_nid_t *addnis = NULL;
+       lnet_nid_t *delnis = NULL;
+       unsigned flags;
+       int ncurnis;
+       int naddnis;
+       int ndelnis;
+       int nnis = 0;
+       int i;
+       int j;
+       int rc;
+
+       flags = LNET_PEER_DISCOVERED;
+       if (pbuf->pb_info.pi_features & LNET_PING_FEAT_MULTI_RAIL)
+               flags |= LNET_PEER_MULTI_RAIL;
+
+       nnis = MAX(lp->lp_nnis, pbuf->pb_info.pi_nnis);
+       LIBCFS_ALLOC(curnis, nnis * sizeof(lnet_nid_t));
+       LIBCFS_ALLOC(addnis, nnis * sizeof(lnet_nid_t));
+       LIBCFS_ALLOC(delnis, nnis * sizeof(lnet_nid_t));
+       if (!curnis || !addnis || !delnis) {
+               rc = -ENOMEM;
+               goto out;
+       }
+       ncurnis = 0;
+       naddnis = 0;
+       ndelnis = 0;
+
+       /* Construct the list of NIDs present in peer. */
+       lpni = NULL;
+       while ((lpni = lnet_get_next_peer_ni_locked(lp, NULL, lpni)) != NULL)
+               curnis[ncurnis++] = lpni->lpni_nid;
+
+       /*
+        * Check for NIDs in pbuf not present in curnis[].
+        * The loop starts at 1 to skip the loopback NID.
+        */
+       for (i = 1; i < pbuf->pb_info.pi_nnis; i++) {
+               for (j = 0; j < ncurnis; j++)
+                       if (pbuf->pb_info.pi_ni[i].ns_nid == curnis[j])
+                               break;
+               if (j == ncurnis)
+                       addnis[naddnis++] = pbuf->pb_info.pi_ni[i].ns_nid;
+       }
+       /*
+        * Check for NIDs in curnis[] not present in pbuf.
+        * The nested loop starts at 1 to skip the loopback NID.
+        *
+        * But never add the loopback NID to delnis[]: if it is
+        * present in curnis[] then this peer is for this node.
+        */
+       for (i = 0; i < ncurnis; i++) {
+               if (LNET_NETTYP(LNET_NIDNET(curnis[i])) == LOLND)
+                       continue;
+               for (j = 1; j < pbuf->pb_info.pi_nnis; j++)
+                       if (curnis[i] == pbuf->pb_info.pi_ni[j].ns_nid)
+                               break;
+               if (j == pbuf->pb_info.pi_nnis)
+                       delnis[ndelnis++] = curnis[i];
+       }
+
+       for (i = 0; i < naddnis; i++) {
+               rc = lnet_peer_add_nid(lp, addnis[i], flags);
+               if (rc) {
+                       CERROR("Error adding NID %s to peer %s: %d\n",
+                              libcfs_nid2str(addnis[i]),
+                              libcfs_nid2str(lp->lp_primary_nid), rc);
+                       if (rc == -ENOMEM)
+                               goto out;
+               }
+       }
+       for (i = 0; i < ndelnis; i++) {
+               rc = lnet_peer_del_nid(lp, delnis[i], flags);
+               if (rc) {
+                       CERROR("Error deleting NID %s from peer %s: %d\n",
+                              libcfs_nid2str(delnis[i]),
+                              libcfs_nid2str(lp->lp_primary_nid), rc);
+                       if (rc == -ENOMEM)
+                               goto out;
+               }
+       }
+       /*
+        * Errors other than -ENOMEM are due to peers having been
+        * configured with DLC. Ignore these because DLC overrides
+        * Discovery.
+        */
+       rc = 0;
+out:
+       LIBCFS_FREE(curnis, nnis * sizeof(lnet_nid_t));
+       LIBCFS_FREE(addnis, nnis * sizeof(lnet_nid_t));
+       LIBCFS_FREE(delnis, nnis * sizeof(lnet_nid_t));
+       lnet_ping_buffer_decref(pbuf);
+       CDEBUG(D_NET, "peer %s: %d\n", libcfs_nid2str(lp->lp_primary_nid), rc);
+
+       if (rc) {
+               spin_lock(&lp->lp_lock);
+               lp->lp_state &= ~LNET_PEER_NIDS_UPTODATE;
+               lp->lp_state |= LNET_PEER_PING_REQUIRED;
+               spin_unlock(&lp->lp_lock);
+       }
+       return rc;
+}
+
+/*
+ * The data in pbuf says lp is its primary peer, but the data was
+ * received by a different peer. Try to update lp with the data.
+ */
+static int
+lnet_peer_set_primary_data(struct lnet_peer *lp, struct lnet_ping_buffer *pbuf)
+{
+       lnet_handle_md_t mdh;
+
+       /* Queue lp for discovery, and force it on the request queue. */
+       lnet_net_lock(LNET_LOCK_EX);
+       if (lnet_peer_queue_for_discovery(lp))
+               list_move(&lp->lp_dc_list, &the_lnet.ln_dc_request);
+       lnet_net_unlock(LNET_LOCK_EX);
+
+       LNetInvalidateHandle(&mdh);
+
+       /*
+        * Decide whether we can move the peer to the DATA_PRESENT state.
+        *
+        * We replace stale data for a multi-rail peer, repair PING_FAILED
+        * status, and preempt PING_REQUIRED.
+        *
+        * If after that we have DATA_PRESENT, we merge it into this peer.
+        */
+       spin_lock(&lp->lp_lock);
+       if (lp->lp_state & LNET_PEER_MULTI_RAIL) {
+               if (lp->lp_peer_seqno < LNET_PING_BUFFER_SEQNO(pbuf)) {
+                       lp->lp_peer_seqno = LNET_PING_BUFFER_SEQNO(pbuf);
+               } else if (lp->lp_state & LNET_PEER_DATA_PRESENT) {
+                       lp->lp_state &= ~LNET_PEER_DATA_PRESENT;
+                       lnet_ping_buffer_decref(pbuf);
+                       pbuf = lp->lp_data;
+                       lp->lp_data = NULL;
+               }
+       }
+       if (lp->lp_state & LNET_PEER_DATA_PRESENT) {
+               lnet_ping_buffer_decref(lp->lp_data);
+               lp->lp_data = NULL;
+               lp->lp_state &= ~LNET_PEER_DATA_PRESENT;
+       }
+       if (lp->lp_state & LNET_PEER_PING_FAILED) {
+               mdh = lp->lp_ping_mdh;
+               LNetInvalidateHandle(&lp->lp_ping_mdh);
+               lp->lp_state &= ~LNET_PEER_PING_FAILED;
+               lp->lp_ping_error = 0;
+       }
+       if (lp->lp_state & LNET_PEER_PING_REQUIRED) {
+               lp->lp_state &= ~LNET_PEER_PING_REQUIRED;
+       }
+       lp->lp_state |= LNET_PEER_NIDS_UPTODATE;
+       spin_unlock(&lp->lp_lock);
+
+       if (!LNetHandleIsInvalid(mdh))
+               LNetMDUnlink(mdh);
+
+       if (pbuf)
+               return lnet_peer_merge_data(lp, pbuf);
+
+       CDEBUG(D_NET, "peer %s\n", libcfs_nid2str(lp->lp_primary_nid));
+       return 0;
+}
+
+/*
+ * Update a peer using the data received.
+ */
+static int lnet_peer_data_present(struct lnet_peer *lp)
+__must_hold(&lp->lp_lock)
+{
+       struct lnet_ping_buffer *pbuf;
+       struct lnet_peer_ni *lpni;
+       lnet_nid_t nid = LNET_NID_ANY;
+       unsigned flags;
+       int rc = 0;
+
+       pbuf = lp->lp_data;
+       lp->lp_data = NULL;
+       lp->lp_state &= ~LNET_PEER_DATA_PRESENT;
+       lp->lp_state |= LNET_PEER_NIDS_UPTODATE;
+       spin_unlock(&lp->lp_lock);
+
+       /*
+        * Modifications of peer structures are done while holding the
+        * ln_api_mutex. A global lock is required because we may be
+        * modifying multiple peer structures, and a mutex greatly
+        * simplifies memory management.
+        *
+        * The actual changes to the data structures must also protect
+        * against concurrent lookups, for which the lnet_net_lock in
+        * LNET_LOCK_EX mode is used.
+        */
+       mutex_lock(&the_lnet.ln_api_mutex);
+       if (the_lnet.ln_state != LNET_STATE_RUNNING) {
+               rc = -ESHUTDOWN;
+               goto out;
+       }
+
+       /*
+        * If this peer is not on the peer list then it is being torn
+        * down, and our reference count may be all that is keeping it
+        * alive. Don't do any work on it.
+        */
+       if (list_empty(&lp->lp_peer_list))
+               goto out;
+
+       flags = LNET_PEER_DISCOVERED;
+       if (pbuf->pb_info.pi_features & LNET_PING_FEAT_MULTI_RAIL)
+               flags |= LNET_PEER_MULTI_RAIL;
+
+       /*
+        * Check whether the primary NID in the message matches the
+        * primary NID of the peer. If it does, update the peer, if
+        * it it does not, check whether there is already a peer with
+        * that primary NID. If no such peer exists, try to update
+        * the primary NID of the current peer (allowed if it was
+        * created due to message traffic) and complete the update.
+        * If the peer did exist, hand off the data to it.
+        *
+        * The peer for the loopback interface is a special case: this
+        * is the peer for the local node, and we want to set its
+        * primary NID to the correct value here.
+        */
+       if (pbuf->pb_info.pi_nnis > 1)
+               nid = pbuf->pb_info.pi_ni[1].ns_nid;
+       if (LNET_NETTYP(LNET_NIDNET(lp->lp_primary_nid)) == LOLND) {
+               rc = lnet_peer_set_primary_nid(lp, nid, flags);
+               if (!rc)
+                       rc = lnet_peer_merge_data(lp, pbuf);
+       } else if (lp->lp_primary_nid == nid) {
+               rc = lnet_peer_merge_data(lp, pbuf);
+       } else {
+               lpni = lnet_find_peer_ni_locked(nid);
+               if (!lpni) {
+                       rc = lnet_peer_set_primary_nid(lp, nid, flags);
+                       if (rc) {
+                               CERROR("Primary NID error %s versus %s: %d\n",
+                                      libcfs_nid2str(lp->lp_primary_nid),
+                                      libcfs_nid2str(nid), rc);
+                       } else {
+                               rc = lnet_peer_merge_data(lp, pbuf);
+                       }
+               } else {
+                       rc = lnet_peer_set_primary_data(
+                               lpni->lpni_peer_net->lpn_peer, pbuf);
+                       lnet_peer_ni_decref_locked(lpni);
+               }
+       }
+out:
+       CDEBUG(D_NET, "peer %s: %d\n", libcfs_nid2str(lp->lp_primary_nid), rc);
+       mutex_unlock(&the_lnet.ln_api_mutex);
+
+       spin_lock(&lp->lp_lock);
+       /* Tell discovery to re-check the peer immediately. */
+       if (!rc)
+               rc = LNET_REDISCOVER_PEER;
+       return rc;
+}
+
+/*
+ * A ping failed. Clear the PING_FAILED state and set the
+ * PING_REQUIRED state, to ensure a retry even if discovery is
+ * disabled. This avoids being left with incorrect state.
+ */
+static int lnet_peer_ping_failed(struct lnet_peer *lp)
+__must_hold(&lp->lp_lock)
+{
+       lnet_handle_md_t mdh;
+       int rc;
+
+       mdh = lp->lp_ping_mdh;
+       LNetInvalidateHandle(&lp->lp_ping_mdh);
+       lp->lp_state &= ~LNET_PEER_PING_FAILED;
+       lp->lp_state |= LNET_PEER_PING_REQUIRED;
+       rc = lp->lp_ping_error;
+       lp->lp_ping_error = 0;
+       spin_unlock(&lp->lp_lock);
+
+       LNetMDUnlink(mdh);
+
+       CDEBUG(D_NET, "peer %s\n", libcfs_nid2str(lp->lp_primary_nid));
+
+       spin_lock(&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_is_peer_ni_healthy_locked(lpni))
+                       continue;
+               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_is_peer_ni_healthy_locked(lpni))
+                       continue;
+               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_md_t md = { NULL };
+       lnet_process_id_t id;
+       struct lnet_ping_buffer *pbuf;
+       int nnis;
+       int rc;
+       int cpt;
+
+       lp->lp_state |= LNET_PEER_PING_SENT;
+       lp->lp_state &= ~LNET_PEER_PING_REQUIRED;
+       spin_unlock(&lp->lp_lock);
+
+       nnis = MAX(lp->lp_data_nnis, LNET_MIN_INTERFACES);
+       pbuf = lnet_ping_buffer_alloc(nnis, GFP_NOFS);
+       if (!pbuf) {
+               rc = -ENOMEM;
+               goto fail_error;
+       }
+
+       /* initialize md content */
+       md.start     = &pbuf->pb_info;
+       md.length    = LNET_PING_INFO_SIZE(nnis);
+       md.threshold = 2; /* GET/REPLY */
+       md.max_size  = 0;
+       md.options   = LNET_MD_TRUNCATE;
+       md.user_ptr  = lp;
+       md.eq_handle = the_lnet.ln_dc_eqh;
+
+       rc = LNetMDBind(md, LNET_UNLINK, &lp->lp_ping_mdh);
+       if (rc != 0) {
+               lnet_ping_buffer_decref(pbuf);
+               CERROR("Can't bind 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);
+       lnet_net_unlock(cpt);
+
+       if (id.nid == LNET_NID_ANY) {
+               rc = -EHOSTUNREACH;
+               goto fail_unlink_md;
+       }
+
+       rc = LNetGet(LNET_NID_ANY, lp->lp_ping_mdh, id,
+                    LNET_RESERVED_PORTAL,
+                    LNET_PROTO_PING_MATCHBITS, 0);
+
+       if (rc)
+               goto fail_unlink_md;
+
+       CDEBUG(D_NET, "peer %s\n", libcfs_nid2str(lp->lp_primary_nid));
+
+       spin_lock(&lp->lp_lock);
+       return 0;
+
+fail_unlink_md:
+       LNetMDUnlink(lp->lp_ping_mdh);
+       LNetInvalidateHandle(&lp->lp_ping_mdh);
+fail_error:
+       CDEBUG(D_NET, "peer %s: %d\n", libcfs_nid2str(lp->lp_primary_nid), rc);
+       /*
+        * The errors that get us here are considered hard errors and
+        * cause Discovery to terminate. Se we clear PING_SENT, but do
+        * not set either PING_FAILED or PING_REQUIRED.
+        */
+       spin_lock(&lp->lp_lock);
+       lp->lp_state &= ~LNET_PEER_PING_SENT;
+       return rc;
+}
+
+/*
+ * This function exists because you cannot call LNetMDUnlink() from an
+ * event handler.
+ */
+static int lnet_peer_push_failed(struct lnet_peer *lp)
+__must_hold(&lp->lp_lock)
+{
+       lnet_handle_md_t mdh;
+       int rc;
+
+       mdh = lp->lp_push_mdh;
+       LNetInvalidateHandle(&lp->lp_push_mdh);
+       lp->lp_state &= ~LNET_PEER_PUSH_FAILED;
+       rc = lp->lp_push_error;
+       lp->lp_push_error = 0;
+       spin_unlock(&lp->lp_lock);
+
+       LNetMDUnlink(mdh);
+
+       CDEBUG(D_NET, "peer %s\n", libcfs_nid2str(lp->lp_primary_nid));
+       spin_lock(&lp->lp_lock);
+       return rc ? rc : LNET_REDISCOVER_PEER;
+}
+
+/* Active side of push. */
+static int lnet_peer_send_push(struct lnet_peer *lp)
+__must_hold(&lp->lp_lock)
+{
+       struct lnet_ping_buffer *pbuf;
+       lnet_process_id_t id;
+       lnet_md_t md;
+       int cpt;
+       int rc;
+
+       LASSERT(lp->lp_state & LNET_PEER_MULTI_RAIL);
+
+       lp->lp_state |= LNET_PEER_PUSH_SENT;
+       spin_unlock(&lp->lp_lock);
+
+       cpt = lnet_net_lock_current();
+       pbuf = the_lnet.ln_ping_target;
+       lnet_ping_buffer_addref(pbuf);
+       lnet_net_unlock(cpt);
+
+       /* Push source MD */
+       md.start     = &pbuf->pb_info;
+       md.length    = LNET_PING_INFO_SIZE(pbuf->pb_nnis);
+       md.threshold = 2; /* Put/Ack */
+       md.max_size  = 0;
+       md.options   = 0;
+       md.eq_handle = the_lnet.ln_dc_eqh;
+       md.user_ptr  = lp;
+
+       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);
+       lnet_net_unlock(cpt);
+
+       if (id.nid == LNET_NID_ANY) {
+               rc = -EHOSTUNREACH;
+               goto fail_unlink;
+       }
+
+       rc = LNetPut(LNET_NID_ANY, lp->lp_push_mdh,
+                    LNET_ACK_REQ, id, LNET_RESERVED_PORTAL,
+                    LNET_PROTO_PING_MATCHBITS, 0, 0);
+
+       if (rc)
+               goto fail_unlink;
+
+       CDEBUG(D_NET, "peer %s\n", libcfs_nid2str(lp->lp_primary_nid));
+
+       spin_lock(&lp->lp_lock);
+       return 0;
+
+fail_unlink:
+       LNetMDUnlink(lp->lp_push_mdh);
+       LNetInvalidateHandle(&lp->lp_push_mdh);
+fail_error:
+       CDEBUG(D_NET, "peer %s: %d\n", libcfs_nid2str(lp->lp_primary_nid), rc);
+       /*
+        * The errors that get us here are considered hard errors and
+        * cause Discovery to terminate. Se we clear PUSH_SENT, but do
+        * not set PUSH_FAILED.
+        */
+       spin_lock(&lp->lp_lock);
+       lp->lp_state &= ~LNET_PEER_PUSH_SENT;
+       return rc;
+}
+
+/*
+ * An unrecoverable error was encountered during discovery.
+ * Set error status in peer and abort discovery.
+ */
+static void lnet_peer_discovery_error(struct lnet_peer *lp, int error)
+{
+       CDEBUG(D_NET, "Discovery error %s: %d\n",
+              libcfs_nid2str(lp->lp_primary_nid), error);
+
+       spin_lock(&lp->lp_lock);
+       lp->lp_dc_error = error;
+       lp->lp_state &= ~LNET_PEER_DISCOVERING;
+       lp->lp_state |= LNET_PEER_UNDISCOVERED;
+       spin_unlock(&lp->lp_lock);
+}
+
+/*
+ * Mark the peer as undiscovered because discovery was disabled.
+ */
+static int lnet_peer_undiscovered(struct lnet_peer *lp)
+__must_hold(&lp->lp_lock)
+{
+
+       lp->lp_state &= ~(LNET_PEER_DISCOVERED | LNET_PEER_DISCOVERING);
+       lp->lp_state |= LNET_PEER_UNDISCOVERED;
+
+       CDEBUG(D_NET, "peer %s\n", libcfs_nid2str(lp->lp_primary_nid));
+
+       return 0;
+}
+
+/*
+ * 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;
+
+       CDEBUG(D_NET, "peer %s\n", libcfs_nid2str(lp->lp_primary_nid));
+
+       return 0;
 }
 
 /*
@@ -1706,6 +2765,8 @@ static int lnet_peer_discovery_wait_for_work(void)
 
        CDEBUG(D_NET, "woken: %d\n", rc);
 
+       CDEBUG(D_NET, "%d\n", rc);
+
        return rc;
 }
 
@@ -1713,6 +2774,7 @@ static int lnet_peer_discovery_wait_for_work(void)
 static int lnet_peer_discovery(void *arg)
 {
        struct lnet_peer *lp;
+       int rc;
 
        CDEBUG(D_NET, "started\n");
        cfs_block_allsigs();
@@ -1733,22 +2795,38 @@ static int lnet_peer_discovery(void *arg)
                        list_move(&lp->lp_dc_list, &the_lnet.ln_dc_working);
                        lnet_net_unlock(LNET_LOCK_EX);
 
-                       /* Just tag and release for now. */
                        spin_lock(&lp->lp_lock);
-                       if (lnet_peer_discovery_enabled) {
-                               lp->lp_state |= (LNET_PEER_DISCOVERED |
-                                                LNET_PEER_NIDS_UPTODATE);
-                               lp->lp_state &= ~(LNET_PEER_UNDISCOVERED |
-                                                 LNET_PEER_DISCOVERING);
-                       } else {
-                               lp->lp_state |= LNET_PEER_UNDISCOVERED;
-                               lp->lp_state &= ~(LNET_PEER_DISCOVERED |
-                                                 LNET_PEER_NIDS_UPTODATE |
-                                                 LNET_PEER_DISCOVERING);
-                       }
+                       CDEBUG(D_NET, "peer %s state %#x\n",
+                               libcfs_nid2str(lp->lp_primary_nid),
+                               lp->lp_state);
+                       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);
+                       else if (lp->lp_state & LNET_PEER_PUSH_FAILED)
+                               rc = lnet_peer_push_failed(lp);
+                       else if (lp->lp_state & LNET_PEER_PING_REQUIRED)
+                               rc = lnet_peer_send_ping(lp);
+                       else if (!lnet_peer_discovery_enabled)
+                               rc = lnet_peer_undiscovered(lp);
+                       else if (!(lp->lp_state & LNET_PEER_NIDS_UPTODATE))
+                               rc = lnet_peer_send_ping(lp);
+                       else if (lnet_peer_needs_push(lp))
+                               rc = lnet_peer_send_push(lp);
+                       else
+                               rc = lnet_peer_discovered(lp);
+                       CDEBUG(D_NET, "peer %s state %#x rc %d\n",
+                               libcfs_nid2str(lp->lp_primary_nid),
+                               lp->lp_state, rc);
                        spin_unlock(&lp->lp_lock);
 
                        lnet_net_lock(LNET_LOCK_EX);
+                       if (rc == LNET_REDISCOVER_PEER) {
+                               list_move(&lp->lp_dc_list,
+                                         &the_lnet.ln_dc_request);
+                       } else if (rc) {
+                               lnet_peer_discovery_error(lp, rc);
+                       }
                        if (!(lp->lp_state & LNET_PEER_DISCOVERING))
                                lnet_peer_discovery_complete(lp);
                        if (the_lnet.ln_dc_state == LNET_DC_STATE_STOPPING)
@@ -1769,21 +2847,11 @@ static int lnet_peer_discovery(void *arg)
 
        lnet_net_lock(LNET_LOCK_EX);
        list_for_each_entry(lp, &the_lnet.ln_dc_request, lp_dc_list) {
-               spin_lock(&lp->lp_lock);
-               lp->lp_state |= LNET_PEER_UNDISCOVERED;
-               lp->lp_state &= ~(LNET_PEER_DISCOVERED |
-                                 LNET_PEER_DISCOVERING |
-                                 LNET_PEER_NIDS_UPTODATE);
-               spin_unlock(&lp->lp_lock);
+               lnet_peer_discovery_error(lp, -ESHUTDOWN);
                lnet_peer_discovery_complete(lp);
        }
        list_for_each_entry(lp, &the_lnet.ln_dc_working, lp_dc_list) {
-               spin_lock(&lp->lp_lock);
-               lp->lp_state |= LNET_PEER_UNDISCOVERED;
-               lp->lp_state &= ~(LNET_PEER_DISCOVERED |
-                                 LNET_PEER_DISCOVERING |
-                                 LNET_PEER_NIDS_UPTODATE);
-               spin_unlock(&lp->lp_lock);
+               lnet_peer_discovery_error(lp, -ESHUTDOWN);
                lnet_peer_discovery_complete(lp);
        }
        lnet_net_unlock(LNET_LOCK_EX);
@@ -1827,6 +2895,8 @@ int lnet_peer_discovery_start(void)
                the_lnet.ln_dc_state = LNET_DC_STATE_SHUTDOWN;
        }
 
+       CDEBUG(D_NET, "discovery start: %d\n", rc);
+
        return rc;
 }
 
@@ -1845,6 +2915,8 @@ void lnet_peer_discovery_stop(void)
 
        LASSERT(list_empty(&the_lnet.ln_dc_request));
        LASSERT(list_empty(&the_lnet.ln_dc_working));
+
+       CDEBUG(D_NET, "discovery stopped\n");
 }
 
 /* Debugging */