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LU-15102 lnet: Reset ni_ping_count only on receive
[fs/lustre-release.git] / lnet / lnet / lib-msg.c
index 445d5a2..1ed75cd 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/lib-msg.c
  *
@@ -48,7 +47,7 @@ lnet_build_unlink_event(struct lnet_libmd *md, struct lnet_event *ev)
        ev->status   = 0;
        ev->unlinked = 1;
        ev->type     = LNET_EVENT_UNLINK;
-       lnet_md_deconstruct(md, &ev->md);
+       lnet_md_deconstruct(md, ev);
        lnet_md2handle(&ev->md_handle, md);
        EXIT;
 }
@@ -360,7 +359,7 @@ lnet_msg_attach_md(struct lnet_msg *msg, struct lnet_libmd *md,
 
        /* build umd in event */
        lnet_md2handle(&msg->msg_ev.md_handle, md);
-       lnet_md_deconstruct(md, &msg->msg_ev.md);
+       lnet_md_deconstruct(md, &msg->msg_ev);
 }
 
 static int
@@ -391,8 +390,6 @@ lnet_complete_msg_locked(struct lnet_msg *msg, int cpt)
                msg->msg_hdr.msg.ack.match_bits = msg->msg_ev.match_bits;
                msg->msg_hdr.msg.ack.mlength = cpu_to_le32(msg->msg_ev.mlength);
 
-               /* NB: we probably want to use NID of msg::msg_from as 3rd
-                * parameter (router NID) if it's routed message */
                rc = lnet_send(msg->msg_ev.target.nid, msg, msg->msg_from);
 
                lnet_net_lock(cpt);
@@ -452,6 +449,31 @@ lnet_dec_healthv_locked(atomic_t *healthv, int sensitivity)
        }
 }
 
+/* must hold net_lock/0 */
+void
+lnet_ni_add_to_recoveryq_locked(struct lnet_ni *ni,
+                               struct list_head *recovery_queue, time64_t now)
+{
+       if (!list_empty(&ni->ni_recovery))
+               return;
+
+       if (atomic_read(&ni->ni_healthv) == LNET_MAX_HEALTH_VALUE)
+               return;
+
+       /* This NI is going on the recovery queue, so take a ref on it */
+       lnet_ni_addref_locked(ni, 0);
+
+       lnet_ni_set_next_ping(ni, now);
+
+       CDEBUG(D_NET, "%s added to recovery queue. ping count: %u next ping: %lld health :%d\n",
+              libcfs_nidstr(&ni->ni_nid),
+              ni->ni_ping_count,
+              ni->ni_next_ping,
+              atomic_read(&ni->ni_healthv));
+
+       list_add_tail(&ni->ni_recovery, recovery_queue);
+}
+
 static void
 lnet_handle_local_failure(struct lnet_ni *local_ni)
 {
@@ -467,35 +489,18 @@ lnet_handle_local_failure(struct lnet_ni *local_ni)
        }
 
        lnet_dec_healthv_locked(&local_ni->ni_healthv, lnet_health_sensitivity);
-       /*
-        * add the NI to the recovery queue if it's not already there
-        * and it's health value is actually below the maximum. It's
-        * possible that the sensitivity might be set to 0, and the health
-        * value will not be reduced. In this case, there is no reason to
-        * invoke recovery
-        */
-       if (list_empty(&local_ni->ni_recovery) &&
-           atomic_read(&local_ni->ni_healthv) < LNET_MAX_HEALTH_VALUE) {
-               CERROR("ni %s added to recovery queue. Health = %d\n",
-                       libcfs_nid2str(local_ni->ni_nid),
-                       atomic_read(&local_ni->ni_healthv));
-               list_add_tail(&local_ni->ni_recovery,
-                             &the_lnet.ln_mt_localNIRecovq);
-               lnet_ni_addref_locked(local_ni, 0);
-       }
+       lnet_ni_add_to_recoveryq_locked(local_ni, &the_lnet.ln_mt_localNIRecovq,
+                                       ktime_get_seconds());
        lnet_net_unlock(0);
 }
 
+/* must hold net_lock/0 */
 void
 lnet_handle_remote_failure_locked(struct lnet_peer_ni *lpni)
 {
        __u32 sensitivity = lnet_health_sensitivity;
        __u32 lp_sensitivity;
 
-       /* lpni could be NULL if we're in the LOLND case */
-       if (!lpni)
-               return;
-
        /*
         * If there is a health sensitivity in the peer then use that
         * instead of the globally set one.
@@ -505,6 +510,10 @@ lnet_handle_remote_failure_locked(struct lnet_peer_ni *lpni)
                sensitivity = lp_sensitivity;
 
        lnet_dec_healthv_locked(&lpni->lpni_healthv, sensitivity);
+
+       /* update the peer_net's health value */
+       lnet_update_peer_net_healthv(lpni);
+
        /*
         * add the peer NI to the recovery queue if it's not already there
         * and it's health value is actually below the maximum. It's
@@ -512,7 +521,9 @@ lnet_handle_remote_failure_locked(struct lnet_peer_ni *lpni)
         * value will not be reduced. In this case, there is no reason to
         * invoke recovery
         */
-       lnet_peer_ni_add_to_recoveryq_locked(lpni);
+       lnet_peer_ni_add_to_recoveryq_locked(lpni,
+                                            &the_lnet.ln_mt_peerNIRecovq,
+                                            ktime_get_seconds());
 }
 
 static void
@@ -533,10 +544,9 @@ lnet_handle_remote_failure(struct lnet_peer_ni *lpni)
 }
 
 static void
-lnet_incr_hstats(struct lnet_msg *msg, enum lnet_msg_hstatus hstatus)
+lnet_incr_hstats(struct lnet_ni *ni, struct lnet_peer_ni *lpni,
+                enum lnet_msg_hstatus hstatus)
 {
-       struct lnet_ni *ni = msg->msg_txni;
-       struct lnet_peer_ni *lpni = msg->msg_txpeer;
        struct lnet_counters_health *health;
 
        health = &the_lnet.ln_counters[0]->lct_health;
@@ -593,6 +603,174 @@ lnet_incr_hstats(struct lnet_msg *msg, enum lnet_msg_hstatus hstatus)
        }
 }
 
+static void
+lnet_resend_msg_locked(struct lnet_msg *msg)
+{
+       msg->msg_retry_count++;
+
+       /*
+        * remove message from the active list and reset it to prepare
+        * for a resend. Two exceptions to this
+        *
+        * 1. the router case. When a message is being routed it is
+        * committed for rx when received and committed for tx when
+        * forwarded. We don't want to remove it from the active list, since
+        * code which handles receiving expects it to remain on the active
+        * list.
+        *
+        * 2. The REPLY case. Reply messages use the same message
+        * structure for the GET that was received.
+        */
+       if (!msg->msg_routing && msg->msg_type != LNET_MSG_REPLY) {
+               list_del_init(&msg->msg_activelist);
+               msg->msg_onactivelist = 0;
+       }
+       /*
+        * The msg_target.nid which was originally set
+        * when calling LNetGet() or LNetPut() might've
+        * been overwritten if we're routing this message.
+        * Call lnet_msg_decommit_tx() to return the credit
+        * this message consumed. The message will
+        * consume another credit when it gets resent.
+        */
+       msg->msg_target.nid = msg->msg_hdr.dest_nid;
+       lnet_msg_decommit_tx(msg, -EAGAIN);
+       msg->msg_sending = 0;
+       msg->msg_receiving = 0;
+       msg->msg_target_is_router = 0;
+
+       CDEBUG(D_NET, "%s->%s:%s:%s - queuing msg (%p) for resend\n",
+              libcfs_nid2str(msg->msg_hdr.src_nid),
+              libcfs_nid2str(msg->msg_hdr.dest_nid),
+              lnet_msgtyp2str(msg->msg_type),
+              lnet_health_error2str(msg->msg_health_status), msg);
+
+       list_add_tail(&msg->msg_list, the_lnet.ln_mt_resendqs[msg->msg_tx_cpt]);
+
+       complete(&the_lnet.ln_mt_wait_complete);
+}
+
+int
+lnet_check_finalize_recursion_locked(struct lnet_msg *msg,
+                                    struct list_head *containerq,
+                                    int nworkers, void **workers)
+{
+       int my_slot = -1;
+       int i;
+
+       list_add_tail(&msg->msg_list, containerq);
+
+       for (i = 0; i < nworkers; i++) {
+               if (workers[i] == current)
+                       break;
+
+               if (my_slot < 0 && workers[i] == NULL)
+                       my_slot = i;
+       }
+
+       if (i < nworkers || my_slot < 0)
+               return -1;
+
+       workers[my_slot] = current;
+
+       return my_slot;
+}
+
+int
+lnet_attempt_msg_resend(struct lnet_msg *msg)
+{
+       struct lnet_msg_container *container;
+       int my_slot;
+       int cpt;
+
+       /* we can only resend tx_committed messages */
+       LASSERT(msg->msg_tx_committed);
+
+       /* don't resend recovery messages */
+       if (msg->msg_recovery) {
+               CDEBUG(D_NET, "msg %s->%s is a recovery ping. retry# %d\n",
+                       libcfs_nid2str(msg->msg_from),
+                       libcfs_nid2str(msg->msg_target.nid),
+                       msg->msg_retry_count);
+               return -ENOTRECOVERABLE;
+       }
+
+       /*
+        * if we explicitly indicated we don't want to resend then just
+        * return
+        */
+       if (msg->msg_no_resend) {
+               CDEBUG(D_NET, "msg %s->%s requested no resend. retry# %d\n",
+                       libcfs_nid2str(msg->msg_from),
+                       libcfs_nid2str(msg->msg_target.nid),
+                       msg->msg_retry_count);
+               return -ENOTRECOVERABLE;
+       }
+
+       /* check if the message has exceeded the number of retries */
+       if (msg->msg_retry_count >= lnet_retry_count) {
+               CNETERR("msg %s->%s exceeded retry count %d\n",
+                       libcfs_nid2str(msg->msg_from),
+                       libcfs_nid2str(msg->msg_target.nid),
+                       msg->msg_retry_count);
+               return -ENOTRECOVERABLE;
+       }
+
+       cpt = msg->msg_tx_cpt;
+       lnet_net_lock(cpt);
+
+       /* check again under lock */
+       if (the_lnet.ln_mt_state != LNET_MT_STATE_RUNNING) {
+               lnet_net_unlock(cpt);
+               return -ESHUTDOWN;
+       }
+
+       container = the_lnet.ln_msg_containers[cpt];
+       my_slot =
+               lnet_check_finalize_recursion_locked(msg,
+                                       &container->msc_resending,
+                                       container->msc_nfinalizers,
+                                       container->msc_resenders);
+
+       /* enough threads are resending */
+       if (my_slot == -1) {
+               lnet_net_unlock(cpt);
+               return 0;
+       }
+
+       while (!list_empty(&container->msc_resending)) {
+               msg = list_entry(container->msc_resending.next,
+                                       struct lnet_msg, msg_list);
+               list_del(&msg->msg_list);
+
+               /*
+                * resending the message will require us to call
+                * lnet_msg_decommit_tx() which will return the credit
+                * which this message holds. This could trigger another
+                * queued message to be sent. If that message fails and
+                * requires a resend we will recurse.
+                * But since at this point the slot is taken, the message
+                * will be queued in the container and dealt with
+                * later. This breaks the recursion.
+                */
+               lnet_resend_msg_locked(msg);
+       }
+
+       /*
+        * msc_resenders is an array of process pointers. Each entry holds
+        * a pointer to the current process operating on the message. An
+        * array entry is created per CPT. If the array slot is already
+        * set, then it means that there is a thread on the CPT currently
+        * resending a message.
+        * Once the thread finishes clear the slot to enable the thread to
+        * take on more resend work.
+        */
+       container->msc_resenders[my_slot] = NULL;
+       lnet_net_unlock(cpt);
+
+       return 0;
+}
+
 /*
  * Do a health check on the message:
  * return -1 if we're not going to handle the error or
@@ -604,9 +782,13 @@ static int
 lnet_health_check(struct lnet_msg *msg)
 {
        enum lnet_msg_hstatus hstatus = msg->msg_health_status;
-       bool lo = false;
-       struct lnet_ni *ni;
        struct lnet_peer_ni *lpni;
+       struct lnet_ni *ni;
+       bool lo = false;
+       bool attempt_local_resend;
+       bool attempt_remote_resend;
+       bool handle_local_health;
+       bool handle_remote_health;
 
        /* if we're shutting down no point in handling health. */
        if (the_lnet.ln_mt_state != LNET_MT_STATE_RUNNING)
@@ -619,10 +801,10 @@ lnet_health_check(struct lnet_msg *msg)
         * set. So no need to sanity check it.
         */
        if (msg->msg_tx_committed &&
-           LNET_NETTYP(LNET_NIDNET(msg->msg_txni->ni_nid)) != LOLND)
+           !nid_is_lo0(&msg->msg_txni->ni_nid))
                LASSERT(msg->msg_txpeer);
        else if (msg->msg_tx_committed &&
-                LNET_NETTYP(LNET_NIDNET(msg->msg_txni->ni_nid)) == LOLND)
+                nid_is_lo0(&msg->msg_txni->ni_nid))
                lo = true;
 
        if (hstatus != LNET_MSG_STATUS_OK &&
@@ -630,25 +812,17 @@ lnet_health_check(struct lnet_msg *msg)
                return -1;
 
        /*
-        * stats are only incremented for errors so avoid wasting time
-        * incrementing statistics if there is no error.
-        */
-       if (hstatus != LNET_MSG_STATUS_OK) {
-               lnet_net_lock(0);
-               lnet_incr_hstats(msg, hstatus);
-               lnet_net_unlock(0);
-       }
-
-       /*
         * always prefer txni/txpeer if they message is committed for both
         * directions.
         */
        if (msg->msg_tx_committed) {
                ni = msg->msg_txni;
                lpni = msg->msg_txpeer;
+               attempt_local_resend = attempt_remote_resend = true;
        } else {
                ni = msg->msg_rxni;
                lpni = msg->msg_rxpeer;
+               attempt_local_resend = attempt_remote_resend = false;
        }
 
        if (!lo)
@@ -657,18 +831,65 @@ lnet_health_check(struct lnet_msg *msg)
                LASSERT(ni);
 
        CDEBUG(D_NET, "health check: %s->%s: %s: %s\n",
-              libcfs_nid2str(ni->ni_nid),
-              (lo) ? "self" : libcfs_nid2str(lpni->lpni_nid),
+              libcfs_nidstr(&ni->ni_nid),
+              (lo) ? "self" : libcfs_nidstr(&lpni->lpni_nid),
               lnet_msgtyp2str(msg->msg_type),
               lnet_health_error2str(hstatus));
 
+       /*
+        * stats are only incremented for errors so avoid wasting time
+        * incrementing statistics if there is no error. Similarly, whether to
+        * update health values or perform resends is only applicable for
+        * messages with a health status != OK.
+        */
+       if (hstatus != LNET_MSG_STATUS_OK) {
+               /* Don't further decrement the health value if a recovery
+                * message failed.
+                */
+               if (msg->msg_recovery)
+                       handle_local_health = handle_remote_health = false;
+               else
+                       handle_local_health = handle_remote_health = true;
+
+               /* For local failures, health/recovery/resends are not needed if
+                * I only have a single (non-lolnd) interface. NB: pb_nnis
+                * includes the lolnd interface, so a single-rail node would
+                * have pb_nnis == 2.
+                */
+               if (the_lnet.ln_ping_target->pb_nnis <= 2) {
+                       handle_local_health = false;
+                       attempt_local_resend = false;
+               }
+
+               lnet_net_lock(0);
+               lnet_incr_hstats(ni, lpni, hstatus);
+               /* For remote failures, health/recovery/resends are not needed
+                * if the peer only has a single interface. Special case for
+                * routers where we rely on health feature to manage route
+                * aliveness. NB: unlike pb_nnis above, lp_nnis does _not_
+                * include the lolnd, so a single-rail node would have
+                * lp_nnis == 1.
+                */
+               if (lpni && lpni->lpni_peer_net &&
+                   lpni->lpni_peer_net->lpn_peer &&
+                   lpni->lpni_peer_net->lpn_peer->lp_nnis <= 1) {
+                       attempt_remote_resend = false;
+                       if (!lnet_isrouter(lpni))
+                               handle_remote_health = false;
+               }
+               lnet_net_unlock(0);
+       }
+
        switch (hstatus) {
        case LNET_MSG_STATUS_OK:
                /*
-                * increment the local ni health weather we successfully
+                * increment the local ni health whether we successfully
                 * received or sent a message on it.
+                *
+                * Ping counts are reset to 0 as appropriate to allow for
+                * faster recovery.
                 */
-               lnet_inc_healthv(&ni->ni_healthv);
+               lnet_inc_healthv(&ni->ni_healthv, lnet_health_sensitivity);
                /*
                 * It's possible msg_txpeer is NULL in the LOLND
                 * case. Only increment the peer's health if we're
@@ -678,16 +899,35 @@ lnet_health_check(struct lnet_msg *msg)
                 * as indication that the router is fully healthy.
                 */
                if (lpni && msg->msg_rx_committed) {
+                       lnet_net_lock(0);
+                       lpni->lpni_ping_count = 0;
+                       ni->ni_ping_count = 0;
                        /*
                         * If we're receiving a message from the router or
                         * I'm a router, then set that lpni's health to
                         * maximum so we can commence communication
                         */
-                       if (lnet_isrouter(lpni) || the_lnet.ln_routing)
-                               lnet_set_healthv(&lpni->lpni_healthv,
-                                                LNET_MAX_HEALTH_VALUE);
-                       else
-                               lnet_inc_healthv(&lpni->lpni_healthv);
+                       if (lnet_isrouter(lpni) || the_lnet.ln_routing) {
+                               lnet_set_lpni_healthv_locked(lpni,
+                                       LNET_MAX_HEALTH_VALUE);
+                       } else {
+                               __u32 sensitivity = lpni->lpni_peer_net->
+                                       lpn_peer->lp_health_sensitivity;
+
+                               lnet_inc_lpni_healthv_locked(lpni,
+                                       (sensitivity) ? sensitivity :
+                                       lnet_health_sensitivity);
+                               /* This peer NI may have previously aged out
+                                * of recovery. Now that we've received a
+                                * message from it, we can continue recovery
+                                * if its health value is still below the
+                                * maximum.
+                                */
+                               lnet_peer_ni_add_to_recoveryq_locked(lpni,
+                                               &the_lnet.ln_mt_peerNIRecovq,
+                                               ktime_get_seconds());
+                       }
+                       lnet_net_unlock(0);
                }
 
                /* we can finalize this message */
@@ -697,147 +937,92 @@ lnet_health_check(struct lnet_msg *msg)
        case LNET_MSG_STATUS_LOCAL_ABORTED:
        case LNET_MSG_STATUS_LOCAL_NO_ROUTE:
        case LNET_MSG_STATUS_LOCAL_TIMEOUT:
-               lnet_handle_local_failure(ni);
-               if (msg->msg_tx_committed)
-                       /* add to the re-send queue */
-                       goto resend;
+               if (handle_local_health)
+                       lnet_handle_local_failure(ni);
+               if (attempt_local_resend)
+                       return lnet_attempt_msg_resend(msg);
                break;
-
-       /*
-        * These errors will not trigger a resend so simply
-        * finalize the message
-        */
        case LNET_MSG_STATUS_LOCAL_ERROR:
-               lnet_handle_local_failure(ni);
+               if (handle_local_health)
+                       lnet_handle_local_failure(ni);
                return -1;
-
-       /*
-        * TODO: since the remote dropped the message we can
-        * attempt a resend safely.
-        */
        case LNET_MSG_STATUS_REMOTE_DROPPED:
-               lnet_handle_remote_failure(lpni);
-               if (msg->msg_tx_committed)
-                       goto resend;
+               if (handle_remote_health)
+                       lnet_handle_remote_failure(lpni);
+               if (attempt_remote_resend)
+                       return lnet_attempt_msg_resend(msg);
                break;
-
        case LNET_MSG_STATUS_REMOTE_ERROR:
        case LNET_MSG_STATUS_REMOTE_TIMEOUT:
+               if (handle_remote_health)
+                       lnet_handle_remote_failure(lpni);
+               return -1;
        case LNET_MSG_STATUS_NETWORK_TIMEOUT:
-               lnet_handle_remote_failure(lpni);
+               if (handle_remote_health)
+                       lnet_handle_remote_failure(lpni);
+               if (handle_local_health)
+                       lnet_handle_local_failure(ni);
                return -1;
        default:
                LBUG();
        }
 
-resend:
-       /* we can only resend tx_committed messages */
-       LASSERT(msg->msg_tx_committed);
-
-       /* don't resend recovery messages */
-       if (msg->msg_recovery) {
-               CDEBUG(D_NET, "msg %s->%s is a recovery ping. retry# %d\n",
-                       libcfs_nid2str(msg->msg_from),
-                       libcfs_nid2str(msg->msg_target.nid),
-                       msg->msg_retry_count);
-               return -1;
-       }
-
-       /*
-        * if we explicitly indicated we don't want to resend then just
-        * return
-        */
-       if (msg->msg_no_resend) {
-               CDEBUG(D_NET, "msg %s->%s requested no resend. retry# %d\n",
-                       libcfs_nid2str(msg->msg_from),
-                       libcfs_nid2str(msg->msg_target.nid),
-                       msg->msg_retry_count);
-               return -1;
-       }
-
-       /* check if the message has exceeded the number of retries */
-       if (msg->msg_retry_count >= lnet_retry_count) {
-               CNETERR("msg %s->%s exceeded retry count %d\n",
-                       libcfs_nid2str(msg->msg_from),
-                       libcfs_nid2str(msg->msg_target.nid),
-                       msg->msg_retry_count);
-               return -1;
-       }
-       msg->msg_retry_count++;
-
-       lnet_net_lock(msg->msg_tx_cpt);
-
-       /* check again under lock */
-       if (the_lnet.ln_mt_state != LNET_MT_STATE_RUNNING) {
-               lnet_net_unlock(msg->msg_tx_cpt);
-               return -1;
-       }
-
-       /*
-        * remove message from the active list and reset it in preparation
-        * for a resend. Two exception to this
-        *
-        * 1. the router case, whe a message is committed for rx when
-        * received, then tx when it is sent. When committed to both tx and
-        * rx we don't want to remove it from the active list.
-        *
-        * 2. The REPLY case since it uses the same msg block for the GET
-        * that was received.
-        */
-       if (!msg->msg_routing && msg->msg_type != LNET_MSG_REPLY) {
-               list_del_init(&msg->msg_activelist);
-               msg->msg_onactivelist = 0;
-       }
-       /*
-        * The msg_target.nid which was originally set
-        * when calling LNetGet() or LNetPut() might've
-        * been overwritten if we're routing this message.
-        * Call lnet_return_tx_credits_locked() to return
-        * the credit this message consumed. The message will
-        * consume another credit when it gets resent.
-        */
-       msg->msg_target.nid = msg->msg_hdr.dest_nid;
-       lnet_msg_decommit_tx(msg, -EAGAIN);
-       msg->msg_sending = 0;
-       msg->msg_receiving = 0;
-       msg->msg_target_is_router = 0;
-
-       CDEBUG(D_NET, "%s->%s:%s:%s - queuing for resend\n",
-              libcfs_nid2str(msg->msg_hdr.src_nid),
-              libcfs_nid2str(msg->msg_hdr.dest_nid),
-              lnet_msgtyp2str(msg->msg_type),
-              lnet_health_error2str(hstatus));
-
-       list_add_tail(&msg->msg_list, the_lnet.ln_mt_resendqs[msg->msg_tx_cpt]);
-       lnet_net_unlock(msg->msg_tx_cpt);
-
-       wake_up(&the_lnet.ln_mt_waitq);
-       return 0;
+       /* no resend is needed */
+       return -1;
 }
 
 static void
-lnet_msg_detach_md(struct lnet_msg *msg, int cpt, int status)
+lnet_msg_detach_md(struct lnet_msg *msg, int status)
 {
        struct lnet_libmd *md = msg->msg_md;
+       lnet_handler_t handler = NULL;
+       int cpt = lnet_cpt_of_cookie(md->md_lh.lh_cookie);
        int unlink;
 
+       lnet_res_lock(cpt);
+       while (md->md_flags & LNET_MD_FLAG_HANDLING)
+               /* An event handler is running - wait for it to
+                * complete to avoid races.
+                */
+               lnet_md_wait_handling(md, cpt);
+
        /* Now it's safe to drop my caller's ref */
        md->md_refcount--;
        LASSERT(md->md_refcount >= 0);
 
        unlink = lnet_md_unlinkable(md);
-       if (md->md_eq != NULL) {
-               msg->msg_ev.status   = status;
+       if (md->md_handler) {
+               if ((md->md_flags & LNET_MD_FLAG_ABORTED) && !status) {
+                       msg->msg_ev.status   = -ETIMEDOUT;
+                       CDEBUG(D_NET, "md 0x%p already unlinked\n", md);
+               } else {
+                       msg->msg_ev.status   = status;
+               }
                msg->msg_ev.unlinked = unlink;
-               lnet_eq_enqueue_event(md->md_eq, &msg->msg_ev);
+               handler = md->md_handler;
+               if (!unlink)
+                       md->md_flags |= LNET_MD_FLAG_HANDLING;
        }
 
-       if (unlink) {
+       if (unlink || (md->md_refcount == 0 &&
+                      md->md_threshold == LNET_MD_THRESH_INF))
                lnet_detach_rsp_tracker(md, cpt);
-               lnet_md_unlink(md);
-       }
 
        msg->msg_md = NULL;
+       if (unlink)
+               lnet_md_unlink(md);
+
+       lnet_res_unlock(cpt);
+
+       if (handler) {
+               handler(&msg->msg_ev);
+               if (!unlink) {
+                       lnet_res_lock(cpt);
+                       md->md_flags &= ~LNET_MD_FLAG_HANDLING;
+                       wake_up_var(md);
+                       lnet_res_unlock(cpt);
+               }
+       }
 }
 
 static bool
@@ -855,8 +1040,13 @@ lnet_is_health_check(struct lnet_msg *msg)
 
        if ((msg->msg_tx_committed && !msg->msg_txpeer) ||
            (msg->msg_rx_committed && !msg->msg_rxpeer)) {
-               CDEBUG(D_NET, "msg %p failed too early to retry and send\n",
-                      msg);
+               /* The optimized GET case does not set msg_rxpeer, but status
+                * could be zero. Only print the error message if we have a
+                * non-zero status.
+                */
+               if (status)
+                       CDEBUG(D_NET, "msg %p status %d cannot retry\n", msg,
+                              status);
                return false;
        }
 
@@ -923,7 +1113,7 @@ lnet_send_error_simulation(struct lnet_msg *msg,
 
        CDEBUG(D_NET, "src %s(%s)->dst %s: %s simulate health error: %s\n",
                libcfs_nid2str(msg->msg_hdr.src_nid),
-               libcfs_nid2str(msg->msg_txni->ni_nid),
+               libcfs_nidstr(&msg->msg_txni->ni_nid),
                libcfs_nid2str(msg->msg_hdr.dest_nid),
                lnet_msgtyp2str(msg->msg_type),
                lnet_health_error2str(*hstatus));
@@ -939,7 +1129,6 @@ lnet_finalize(struct lnet_msg *msg, int status)
        int my_slot;
        int cpt;
        int rc;
-       int i;
 
        LASSERT(!in_interrupt());
 
@@ -962,7 +1151,6 @@ lnet_finalize(struct lnet_msg *msg, int status)
                 * put on the resend queue.
                 */
                if (!lnet_health_check(msg))
-                       /* Message is queued for resend */
                        return;
        }
 
@@ -970,12 +1158,8 @@ lnet_finalize(struct lnet_msg *msg, int status)
         * We're not going to resend this message so detach its MD and invoke
         * the appropriate callbacks
         */
-       if (msg->msg_md != NULL) {
-               cpt = lnet_cpt_of_cookie(msg->msg_md->md_lh.lh_cookie);
-               lnet_res_lock(cpt);
-               lnet_msg_detach_md(msg, cpt, status);
-               lnet_res_unlock(cpt);
-       }
+       if (msg->msg_md != NULL)
+               lnet_msg_detach_md(msg, status);
 
 again:
        if (!msg->msg_tx_committed && !msg->msg_rx_committed) {
@@ -994,27 +1178,20 @@ again:
        lnet_net_lock(cpt);
 
        container = the_lnet.ln_msg_containers[cpt];
-       list_add_tail(&msg->msg_list, &container->msc_finalizing);
 
        /* Recursion breaker.  Don't complete the message here if I am (or
         * enough other threads are) already completing messages */
+       my_slot = lnet_check_finalize_recursion_locked(msg,
+                                               &container->msc_finalizing,
+                                               container->msc_nfinalizers,
+                                               container->msc_finalizers);
 
-       my_slot = -1;
-       for (i = 0; i < container->msc_nfinalizers; i++) {
-               if (container->msc_finalizers[i] == current)
-                       break;
-
-               if (my_slot < 0 && container->msc_finalizers[i] == NULL)
-                       my_slot = i;
-       }
-
-       if (i < container->msc_nfinalizers || my_slot < 0) {
+       /* enough threads are resending */
+       if (my_slot == -1) {
                lnet_net_unlock(cpt);
                return;
        }
 
-       container->msc_finalizers[my_slot] = current;
-
        rc = 0;
        while (!list_empty(&container->msc_finalizing)) {
                msg = list_entry(container->msc_finalizing.next,
@@ -1067,11 +1244,16 @@ lnet_msg_container_cleanup(struct lnet_msg_container *container)
                CERROR("%d active msg on exit\n", count);
 
        if (container->msc_finalizers != NULL) {
-               LIBCFS_FREE(container->msc_finalizers,
-                           container->msc_nfinalizers *
-                           sizeof(*container->msc_finalizers));
+               CFS_FREE_PTR_ARRAY(container->msc_finalizers,
+                                  container->msc_nfinalizers);
                container->msc_finalizers = NULL;
        }
+
+       if (container->msc_resenders != NULL) {
+               CFS_FREE_PTR_ARRAY(container->msc_resenders,
+                                  container->msc_nfinalizers);
+               container->msc_resenders = NULL;
+       }
        container->msc_init = 0;
 }
 
@@ -1084,6 +1266,7 @@ lnet_msg_container_setup(struct lnet_msg_container *container, int cpt)
 
        INIT_LIST_HEAD(&container->msc_active);
        INIT_LIST_HEAD(&container->msc_finalizing);
+       INIT_LIST_HEAD(&container->msc_resending);
 
        /* number of CPUs */
        container->msc_nfinalizers = cfs_cpt_weight(lnet_cpt_table(), cpt);
@@ -1100,6 +1283,16 @@ lnet_msg_container_setup(struct lnet_msg_container *container, int cpt)
                return -ENOMEM;
        }
 
+       LIBCFS_CPT_ALLOC(container->msc_resenders, lnet_cpt_table(), cpt,
+                        container->msc_nfinalizers *
+                        sizeof(*container->msc_resenders));
+
+       if (container->msc_resenders == NULL) {
+               CERROR("Failed to allocate message resenders\n");
+               lnet_msg_container_cleanup(container);
+               return -ENOMEM;
+       }
+
        return rc;
 }