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[fs/lustre-release.git] / lnet / klnds / socklnd / socklnd_cb.c
index 024c306..d73314c 100644 (file)
 #include "socklnd.h"
 
 ksock_tx_t *
-ksocknal_alloc_tx (int size)
+ksocknal_alloc_tx(int type, int size)
 {
         ksock_tx_t *tx = NULL;
 
-        if (size == KSOCK_NOOP_TX_SIZE) {
+        if (type == KSOCK_MSG_NOOP) {
+                LASSERT (size == KSOCK_NOOP_TX_SIZE);
+
                 /* searching for a noop tx in free list */
                 cfs_spin_lock(&ksocknal_data.ksnd_tx_lock);
 
@@ -52,18 +54,47 @@ ksocknal_alloc_tx (int size)
                 return NULL;
 
         cfs_atomic_set(&tx->tx_refcount, 1);
-        tx->tx_desc_size = size;
+        tx->tx_zc_capable = 0;
+        tx->tx_zc_checked = 0;
+        tx->tx_desc_size  = size;
+
         cfs_atomic_inc(&ksocknal_data.ksnd_nactive_txs);
 
         return tx;
 }
 
+ksock_tx_t *
+ksocknal_alloc_tx_noop(__u64 cookie, int nonblk)
+{
+        ksock_tx_t *tx;
+
+        tx = ksocknal_alloc_tx(KSOCK_MSG_NOOP, KSOCK_NOOP_TX_SIZE);
+        if (tx == NULL) {
+                CERROR("Can't allocate noop tx desc\n");
+                return NULL;
+        }
+
+        tx->tx_conn     = NULL;
+        tx->tx_lnetmsg  = NULL;
+        tx->tx_kiov     = NULL;
+        tx->tx_nkiov    = 0;
+        tx->tx_iov      = tx->tx_frags.virt.iov;
+        tx->tx_niov     = 1;
+        tx->tx_nonblk   = nonblk;
+
+        socklnd_init_msg(&tx->tx_msg, KSOCK_MSG_NOOP);
+        tx->tx_msg.ksm_zc_cookies[1] = cookie;
+
+        return tx;
+}
+
+
 void
 ksocknal_free_tx (ksock_tx_t *tx)
 {
         cfs_atomic_dec(&ksocknal_data.ksnd_nactive_txs);
 
-        if (tx->tx_desc_size == KSOCK_NOOP_TX_SIZE) {
+        if (tx->tx_lnetmsg == NULL && tx->tx_desc_size == KSOCK_NOOP_TX_SIZE) {
                 /* it's a noop tx */
                 cfs_spin_lock(&ksocknal_data.ksnd_tx_lock);
 
@@ -75,15 +106,6 @@ ksocknal_free_tx (ksock_tx_t *tx)
         }
 }
 
-void
-ksocknal_init_msg(ksock_msg_t *msg, int type)
-{
-        msg->ksm_type           = type;
-        msg->ksm_csum           = 0;
-        msg->ksm_zc_req_cookie  = 0;
-        msg->ksm_zc_ack_cookie  = 0;
-}
-
 int
 ksocknal_send_iov (ksock_conn_t *conn, ksock_tx_t *tx)
 {
@@ -396,7 +418,7 @@ ksocknal_txlist_done (lnet_ni_t *ni, struct list_head *txlist, int error)
                                 le32_to_cpu (tx->tx_lnetmsg->msg_hdr.type),
                                 le32_to_cpu (tx->tx_lnetmsg->msg_hdr.payload_length),
                                 libcfs_nid2str(le64_to_cpu(tx->tx_lnetmsg->msg_hdr.src_nid)),
-                                libcfs_nid2str(le64_to_cpu (tx->tx_lnetmsg->msg_hdr.dest_nid)));
+                                libcfs_nid2str(le64_to_cpu(tx->tx_lnetmsg->msg_hdr.dest_nid)));
                 } else if (error) {
                         CDEBUG (D_NETERROR, "Deleting noop packet\n");
                 }
@@ -413,32 +435,24 @@ ksocknal_check_zc_req(ksock_tx_t *tx)
 {
         ksock_conn_t   *conn = tx->tx_conn;
         ksock_peer_t   *peer = conn->ksnc_peer;
-        lnet_kiov_t    *kiov = tx->tx_kiov;
-        int             nkiov = tx->tx_nkiov;
 
-        /* Set tx_msg.ksm_zc_req_cookie to a unique non-zero cookie and add tx
+        /* Set tx_msg.ksm_zc_cookies[0] to a unique non-zero cookie and add tx
          * to ksnp_zc_req_list if some fragment of this message should be sent
          * zero-copy.  Our peer will send an ACK containing this cookie when
          * she has received this message to tell us we can signal completion.
-         * tx_msg.ksm_zc_req_cookie remains non-zero while tx is on
+         * tx_msg.ksm_zc_cookies[0] remains non-zero while tx is on
          * ksnp_zc_req_list. */
+        LASSERT (tx->tx_msg.ksm_type != KSOCK_MSG_NOOP);
+        LASSERT (tx->tx_zc_capable);
 
-        if (conn->ksnc_proto != &ksocknal_protocol_v2x ||
-            !conn->ksnc_zc_capable)
-                return;
+        tx->tx_zc_checked = 1;
 
-        while (nkiov > 0) {
-                if (kiov->kiov_len >= *ksocknal_tunables.ksnd_zc_min_frag)
-                        break;
-                --nkiov;
-                ++kiov;
-        }
-
-        if (nkiov == 0)
+        if (conn->ksnc_proto == &ksocknal_protocol_v1x ||
+            !conn->ksnc_zc_capable)
                 return;
 
         /* assign cookie and queue tx to pending list, it will be released when
-         * a matching ack is received. See ksocknal_handle_zc_ack() */
+         * a matching ack is received. See ksocknal_handle_zcack() */
 
         ksocknal_tx_addref(tx);
 
@@ -448,27 +462,37 @@ ksocknal_check_zc_req(ksock_tx_t *tx)
         tx->tx_deadline =
                 cfs_time_shift(*ksocknal_tunables.ksnd_timeout);
 
-        LASSERT (tx->tx_msg.ksm_zc_req_cookie == 0);
-        tx->tx_msg.ksm_zc_req_cookie = peer->ksnp_zc_next_cookie++;
+        LASSERT (tx->tx_msg.ksm_zc_cookies[0] == 0);
+
+        tx->tx_msg.ksm_zc_cookies[0] = peer->ksnp_zc_next_cookie++;
+
+        if (peer->ksnp_zc_next_cookie == 0)
+                peer->ksnp_zc_next_cookie = SOCKNAL_KEEPALIVE_PING + 1;
+
         list_add_tail(&tx->tx_zc_list, &peer->ksnp_zc_req_list);
 
         cfs_spin_unlock(&peer->ksnp_lock);
 }
 
 static void
-ksocknal_unzc_req(ksock_tx_t *tx)
+ksocknal_uncheck_zc_req(ksock_tx_t *tx)
 {
         ksock_peer_t   *peer = tx->tx_conn->ksnc_peer;
 
+        LASSERT (tx->tx_msg.ksm_type != KSOCK_MSG_NOOP);
+        LASSERT (tx->tx_zc_capable);
+
+        tx->tx_zc_checked = 0;
+
         cfs_spin_lock(&peer->ksnp_lock);
 
-        if (tx->tx_msg.ksm_zc_req_cookie == 0) {
+        if (tx->tx_msg.ksm_zc_cookies[0] == 0) {
                 /* Not waiting for an ACK */
                 cfs_spin_unlock(&peer->ksnp_lock);
                 return;
         }
 
-        tx->tx_msg.ksm_zc_req_cookie = 0;
+        tx->tx_msg.ksm_zc_cookies[0] = 0;
         list_del(&tx->tx_zc_list);
 
         cfs_spin_unlock(&peer->ksnp_lock);
@@ -481,10 +505,8 @@ ksocknal_process_transmit (ksock_conn_t *conn, ksock_tx_t *tx)
 {
         int            rc;
 
-        if (!tx->tx_checked_zc) {
-                tx->tx_checked_zc = 1;
+        if (tx->tx_zc_capable && !tx->tx_zc_checked)
                 ksocknal_check_zc_req(tx);
-        }
 
         rc = ksocknal_transmit (conn, tx);
 
@@ -548,7 +570,8 @@ ksocknal_process_transmit (ksock_conn_t *conn, ksock_tx_t *tx)
                        conn->ksnc_port);
         }
 
-        ksocknal_unzc_req(tx);
+        if (tx->tx_zc_checked)
+                ksocknal_uncheck_zc_req(tx);
 
         /* it's not an error if conn is being closed */
         ksocknal_close_conn_and_siblings (conn,
@@ -580,123 +603,70 @@ ksocknal_launch_connection_locked (ksock_route_t *route)
 }
 
 ksock_conn_t *
-ksocknal_find_conn_locked (int payload_nob, ksock_peer_t *peer)
+ksocknal_find_conn_locked(ksock_peer_t *peer, ksock_tx_t *tx, int nonblk)
 {
         struct list_head *tmp;
+        ksock_conn_t     *conn;
         ksock_conn_t     *typed = NULL;
-        int               tnob  = 0;
         ksock_conn_t     *fallback = NULL;
+        int               tnob     = 0;
         int               fnob     = 0;
-        ksock_conn_t     *conn;
 
         list_for_each (tmp, &peer->ksnp_conns) {
-                ksock_conn_t *c = list_entry(tmp, ksock_conn_t, ksnc_list);
-                int           hdr_nob = 0;
-#if SOCKNAL_ROUND_ROBIN
-                const int     nob = 0;
-#else
+                ksock_conn_t *c   = list_entry(tmp, ksock_conn_t, ksnc_list);
                 int           nob = cfs_atomic_read(&c->ksnc_tx_nob) +
-                                        libcfs_sock_wmem_queued(c->ksnc_sock);
-#endif
-                LASSERT (!c->ksnc_closing);
-                LASSERT (c->ksnc_proto != NULL);
+                                    libcfs_sock_wmem_queued(c->ksnc_sock);
+                int           rc;
 
-                if (fallback == NULL || nob < fnob) {
-                        fallback = c;
-                        fnob     = nob;
-                }
-
-                if (!*ksocknal_tunables.ksnd_typed_conns)
-                        continue;
+                LASSERT (!c->ksnc_closing);
+                LASSERT (c->ksnc_proto != NULL &&
+                         c->ksnc_proto->pro_match_tx != NULL);
 
-                if (payload_nob == 0) {
-                        /* noop packet */
-                        hdr_nob = offsetof(ksock_msg_t, ksm_u);
-                } else {
-                        /* lnet packet */
-                        hdr_nob = (c->ksnc_proto == &ksocknal_protocol_v2x)?
-                                  sizeof(ksock_msg_t) : sizeof(lnet_hdr_t);
-                }
+                rc = c->ksnc_proto->pro_match_tx(c, tx, nonblk);
 
-                switch (c->ksnc_type) {
+                switch (rc) {
                 default:
-                        CERROR("ksnc_type bad: %u\n", c->ksnc_type);
                         LBUG();
-                case SOCKLND_CONN_ANY:
-                        break;
-                case SOCKLND_CONN_BULK_IN:
+                case SOCKNAL_MATCH_NO: /* protocol rejected the tx */
                         continue;
-                case SOCKLND_CONN_BULK_OUT:
-                        if ((hdr_nob + payload_nob) < *ksocknal_tunables.ksnd_min_bulk)
-                                continue;
-                        break;
-                case SOCKLND_CONN_CONTROL:
-                        if ((hdr_nob + payload_nob) >= *ksocknal_tunables.ksnd_min_bulk)
-                                continue;
+
+                case SOCKNAL_MATCH_YES: /* typed connection */
+                        if (typed == NULL || tnob > nob ||
+                            (tnob == nob && *ksocknal_tunables.ksnd_round_robin &&
+                             cfs_time_after(typed->ksnc_tx_last_post, c->ksnc_tx_last_post))) {
+                                typed = c;
+                                tnob  = nob;
+                        }
                         break;
-                }
 
-                if (typed == NULL || nob < tnob) {
-                        typed = c;
-                        tnob  = nob;
+                case SOCKNAL_MATCH_MAY: /* fallback connection */
+                        if (fallback == NULL || fnob > nob ||
+                            (fnob == nob && *ksocknal_tunables.ksnd_round_robin &&
+                             cfs_time_after(fallback->ksnc_tx_last_post, c->ksnc_tx_last_post))) {
+                                fallback = c;
+                                fnob     = nob;
+                        }
+                        break;
                 }
         }
 
         /* prefer the typed selection */
         conn = (typed != NULL) ? typed : fallback;
 
-#if SOCKNAL_ROUND_ROBIN
-        if (conn != NULL) {
-                /* round-robin all else being equal */
-                list_del (&conn->ksnc_list);
-                list_add_tail (&conn->ksnc_list, &peer->ksnp_conns);
-        }
-#endif
+        if (conn != NULL)
+                conn->ksnc_tx_last_post = cfs_time_current();
+
         return conn;
 }
 
 void
-ksocknal_next_mono_tx(ksock_conn_t *conn)
-{
-        ksock_tx_t     *tx = conn->ksnc_tx_mono;
-
-        /* Called holding BH lock: conn->ksnc_scheduler->kss_lock */
-        LASSERT(conn->ksnc_proto == &ksocknal_protocol_v2x);
-        LASSERT(!list_empty(&conn->ksnc_tx_queue));
-        LASSERT(tx != NULL);
-
-        if (tx->tx_list.next == &conn->ksnc_tx_queue) {
-                /* no more packets queued */
-                conn->ksnc_tx_mono = NULL;
-        } else {
-                conn->ksnc_tx_mono = list_entry(tx->tx_list.next, ksock_tx_t, tx_list);
-                LASSERT(conn->ksnc_tx_mono->tx_msg.ksm_type == tx->tx_msg.ksm_type);
-        }
-}
-
-int
-ksocknal_piggyback_zcack(ksock_conn_t *conn, __u64 cookie)
+ksocknal_tx_prep(ksock_conn_t *conn, ksock_tx_t *tx)
 {
-        ksock_tx_t     *tx = conn->ksnc_tx_mono;
-
-        /* Called holding BH lock: conn->ksnc_scheduler->kss_lock */
-
-        if (tx == NULL)
-                return 0;
-
-        if (tx->tx_msg.ksm_type == KSOCK_MSG_NOOP) {
-                /* tx is noop zc-ack, can't piggyback zc-ack cookie */
-                return 0;
-        }
-
-        LASSERT(tx->tx_msg.ksm_type == KSOCK_MSG_LNET);
-        LASSERT(tx->tx_msg.ksm_zc_ack_cookie == 0);
-
-        /* piggyback the zc-ack cookie */
-        tx->tx_msg.ksm_zc_ack_cookie = cookie;
-        ksocknal_next_mono_tx(conn);
+        conn->ksnc_proto->pro_pack(tx);
 
-        return 1;
+        cfs_atomic_add (tx->tx_nob, &conn->ksnc_tx_nob);
+        ksocknal_conn_addref(conn); /* +1 ref for tx */
+        tx->tx_conn = conn;
 }
 
 void
@@ -704,7 +674,7 @@ ksocknal_queue_tx_locked (ksock_tx_t *tx, ksock_conn_t *conn)
 {
         ksock_sched_t *sched = conn->ksnc_scheduler;
         ksock_msg_t   *msg = &tx->tx_msg;
-        ksock_tx_t    *ztx;
+        ksock_tx_t    *ztx = NULL;
         int            bufnob = 0;
 
         /* called holding global lock (read or irq-write) and caller may
@@ -713,13 +683,12 @@ ksocknal_queue_tx_locked (ksock_tx_t *tx, ksock_conn_t *conn)
          * ksnc_sock... */
         LASSERT(!conn->ksnc_closing);
 
-        CDEBUG (D_NET, "Sending to %s ip %d.%d.%d.%d:%d\n",
+        CDEBUG (D_NET, "Sending to %s ip %d.%d.%d.%d:%d\n", 
                 libcfs_id2str(conn->ksnc_peer->ksnp_id),
                 HIPQUAD(conn->ksnc_ipaddr),
                 conn->ksnc_port);
 
-        tx->tx_checked_zc = 0;
-        conn->ksnc_proto->pro_pack(tx);
+        ksocknal_tx_prep(conn, tx);
 
         /* Ensure the frags we've been given EXACTLY match the number of
          * bytes we want to send.  Many TCP/IP stacks disregard any total
@@ -734,14 +703,10 @@ ksocknal_queue_tx_locked (ksock_tx_t *tx, ksock_conn_t *conn)
         LASSERT (tx->tx_resid == tx->tx_nob);
 
         CDEBUG (D_NET, "Packet %p type %d, nob %d niov %d nkiov %d\n",
-                tx, (tx->tx_lnetmsg != NULL)? tx->tx_lnetmsg->msg_hdr.type:
-                                              KSOCK_MSG_NOOP,
+                tx, (tx->tx_lnetmsg != NULL) ? tx->tx_lnetmsg->msg_hdr.type:
+                                               KSOCK_MSG_NOOP,
                 tx->tx_nob, tx->tx_niov, tx->tx_nkiov);
 
-        cfs_atomic_add (tx->tx_nob, &conn->ksnc_tx_nob);
-        tx->tx_conn = conn;
-        ksocknal_conn_addref(conn); /* +1 ref for tx */
-
         /*
          * FIXME: SOCK_WMEM_QUEUED and SOCK_ERROR could block in __DARWIN8__
          * but they're used inside spinlocks a lot.
@@ -757,67 +722,29 @@ ksocknal_queue_tx_locked (ksock_tx_t *tx, ksock_conn_t *conn)
                 cfs_mb(); /* order with adding to tx_queue */
         }
 
-        ztx = NULL;
-
         if (msg->ksm_type == KSOCK_MSG_NOOP) {
                 /* The packet is noop ZC ACK, try to piggyback the ack_cookie
                  * on a normal packet so I don't need to send it */
-                LASSERT(msg->ksm_zc_req_cookie == 0);
-                LASSERT(msg->ksm_zc_ack_cookie != 0);
-
-                if (conn->ksnc_tx_mono != NULL) {
-                        if (ksocknal_piggyback_zcack(conn, msg->ksm_zc_ack_cookie)) {
-                                /* zc-ack cookie is piggybacked */
-                                cfs_atomic_sub (tx->tx_nob, &conn->ksnc_tx_nob);
-                                ztx = tx;       /* Put to freelist later */
-                        } else {
-                                /* no packet can piggyback zc-ack cookie */
-                                list_add_tail (&tx->tx_list, &conn->ksnc_tx_queue);
-                        }
-                } else {
-                        /* It's the first mono-packet */
-                        conn->ksnc_tx_mono = tx;
-                        list_add_tail (&tx->tx_list, &conn->ksnc_tx_queue);
-                }
+                LASSERT (msg->ksm_zc_cookies[1] != 0);
+                LASSERT (conn->ksnc_proto->pro_queue_tx_zcack != NULL);
+
+                if (conn->ksnc_proto->pro_queue_tx_zcack(conn, tx, 0))
+                        ztx = tx; /* ZC ACK piggybacked on ztx release tx later */
 
         } else {
                 /* It's a normal packet - can it piggback a noop zc-ack that
                  * has been queued already? */
-                LASSERT(msg->ksm_zc_ack_cookie == 0);
-
-                if (conn->ksnc_proto == &ksocknal_protocol_v2x &&  /* V2.x packet */
-                    conn->ksnc_tx_mono != NULL) {
-                        if (conn->ksnc_tx_mono->tx_msg.ksm_type == KSOCK_MSG_NOOP) {
-                                /* There is a noop zc-ack can be piggybacked */
-                                ztx = conn->ksnc_tx_mono;
-
-                                msg->ksm_zc_ack_cookie = ztx->tx_msg.ksm_zc_ack_cookie;
-                                ksocknal_next_mono_tx(conn);
-
-                                /* use tx to replace the noop zc-ack packet, ztx will
-                                 * be put to freelist later */
-                                list_add(&tx->tx_list, &ztx->tx_list);
-                                list_del(&ztx->tx_list);
-
-                                cfs_atomic_sub (ztx->tx_nob, &conn->ksnc_tx_nob);
-                        } else {
-                                /* no noop zc-ack packet, just enqueue it */
-                                LASSERT(conn->ksnc_tx_mono->tx_msg.ksm_type == KSOCK_MSG_LNET);
-                                list_add_tail (&tx->tx_list, &conn->ksnc_tx_queue);
-                        }
+                LASSERT (msg->ksm_zc_cookies[1] == 0);
+                LASSERT (conn->ksnc_proto->pro_queue_tx_msg != NULL);
 
-                } else if (conn->ksnc_proto == &ksocknal_protocol_v2x) {
-                        /* it's the first mono-packet, enqueue it */
-                        conn->ksnc_tx_mono = tx;
-                        list_add_tail (&tx->tx_list, &conn->ksnc_tx_queue);
-                } else {
-                        /* V1.x packet, just enqueue it */
-                        list_add_tail (&tx->tx_list, &conn->ksnc_tx_queue);
-                }
+                ztx = conn->ksnc_proto->pro_queue_tx_msg(conn, tx);
+                /* ztx will be released later */
         }
 
-        if (ztx != NULL)
+        if (ztx != NULL) {
+                cfs_atomic_sub (ztx->tx_nob, &conn->ksnc_tx_nob);
                 list_add_tail(&ztx->tx_list, &sched->kss_zombie_noop_txs);
+        }
 
         if (conn->ksnc_tx_ready &&      /* able to send */
             !conn->ksnc_tx_scheduled) { /* not scheduled to send */
@@ -832,6 +759,7 @@ ksocknal_queue_tx_locked (ksock_tx_t *tx, ksock_conn_t *conn)
         cfs_spin_unlock_bh (&sched->kss_lock);
 }
 
+
 ksock_route_t *
 ksocknal_find_connectable_route_locked (ksock_peer_t *peer)
 {
@@ -891,17 +819,15 @@ ksocknal_launch_packet (lnet_ni_t *ni, ksock_tx_t *tx, lnet_process_id_t id)
         int               rc;
 
         LASSERT (tx->tx_conn == NULL);
-        LASSERT (tx->tx_lnetmsg != NULL);
 
         g_lock = &ksocknal_data.ksnd_global_lock;
 
         for (retry = 0;; retry = 1) {
-#if !SOCKNAL_ROUND_ROBIN
                 cfs_read_lock (g_lock);
                 peer = ksocknal_find_peer_locked(ni, id);
                 if (peer != NULL) {
                         if (ksocknal_find_connectable_route_locked(peer) == NULL) {
-                                conn = ksocknal_find_conn_locked (tx->tx_lnetmsg->msg_len, peer);
+                                conn = ksocknal_find_conn_locked(peer, tx, tx->tx_nonblk);
                                 if (conn != NULL) {
                                         /* I've got no routes that need to be
                                          * connecting and I do have an actual
@@ -915,7 +841,7 @@ ksocknal_launch_packet (lnet_ni_t *ni, ksock_tx_t *tx, lnet_process_id_t id)
 
                 /* I'll need a write lock... */
                 cfs_read_unlock (g_lock);
-#endif
+
                 cfs_write_lock_bh (g_lock);
 
                 peer = ksocknal_find_peer_locked(ni, id);
@@ -954,7 +880,7 @@ ksocknal_launch_packet (lnet_ni_t *ni, ksock_tx_t *tx, lnet_process_id_t id)
                 ksocknal_launch_connection_locked (route);
         }
 
-        conn = ksocknal_find_conn_locked (tx->tx_lnetmsg->msg_len, peer);
+        conn = ksocknal_find_conn_locked(peer, tx, tx->tx_nonblk);
         if (conn != NULL) {
                 /* Connection exists; queue message on it */
                 ksocknal_queue_tx_locked (tx, conn);
@@ -967,7 +893,7 @@ ksocknal_launch_packet (lnet_ni_t *ni, ksock_tx_t *tx, lnet_process_id_t id)
                 /* the message is going to be pinned to the peer */
                 tx->tx_deadline =
                         cfs_time_shift(*ksocknal_tunables.ksnd_timeout);
-                
+
                 /* Queue the message until a connection is established */
                 list_add_tail (&tx->tx_list, &peer->ksnp_tx_queue);
                 cfs_write_unlock_bh (g_lock);
@@ -1014,7 +940,7 @@ ksocknal_send(lnet_ni_t *ni, void *private, lnet_msg_t *lntmsg)
                 desc_size = offsetof(ksock_tx_t,
                                      tx_frags.paged.kiov[payload_niov]);
 
-        tx = ksocknal_alloc_tx(desc_size);
+        tx = ksocknal_alloc_tx(KSOCK_MSG_LNET, desc_size);
         if (tx == NULL) {
                 CERROR("Can't allocate tx desc type %d size %d\n",
                        type, desc_size);
@@ -1039,9 +965,12 @@ ksocknal_send(lnet_ni_t *ni, void *private, lnet_msg_t *lntmsg)
                 tx->tx_nkiov = lnet_extract_kiov(payload_niov, tx->tx_kiov,
                                                  payload_niov, payload_kiov,
                                                  payload_offset, payload_nob);
+
+                if (payload_nob >= *ksocknal_tunables.ksnd_zc_min_payload)
+                        tx->tx_zc_capable = 1;
         }
 
-        ksocknal_init_msg(&tx->tx_msg, KSOCK_MSG_LNET);
+        socklnd_init_msg(&tx->tx_msg, KSOCK_MSG_LNET);
 
         /* The first fragment will be set later in pro_pack */
         rc = ksocknal_launch_packet(ni, tx, target);
@@ -1096,6 +1025,7 @@ ksocknal_new_packet (ksock_conn_t *conn, int nob_to_skip)
 
                 switch (conn->ksnc_proto->pro_version) {
                 case  KSOCK_PROTO_V2:
+                case  KSOCK_PROTO_V3:
                         conn->ksnc_rx_state = SOCKNAL_RX_KSM_HEADER;
                         conn->ksnc_rx_iov = (struct iovec *)&conn->ksnc_rx_iov_space;
                         conn->ksnc_rx_iov[0].iov_base = (char *)&conn->ksnc_msg;
@@ -1155,99 +1085,12 @@ ksocknal_new_packet (ksock_conn_t *conn, int nob_to_skip)
         return (0);
 }
 
-/* (Sink) handle incoming ZC request from sender */
-static int
-ksocknal_handle_zc_req(ksock_peer_t *peer, __u64 cookie)
-{
-        ksock_conn_t   *conn;
-        ksock_tx_t     *tx;
-        ksock_sched_t  *sched;
-        int             rc;
-
-        cfs_read_lock (&ksocknal_data.ksnd_global_lock);
-
-        conn = ksocknal_find_conn_locked (0, peer);
-        if (conn == NULL) {
-                cfs_read_unlock (&ksocknal_data.ksnd_global_lock);
-                CERROR("Can't find connection to send zcack.\n");
-                return -ECONNRESET;
-        }
-
-        sched = conn->ksnc_scheduler;
-
-        cfs_spin_lock_bh (&sched->kss_lock);
-        rc = ksocknal_piggyback_zcack(conn, cookie);
-        cfs_spin_unlock_bh (&sched->kss_lock);
-
-        cfs_read_unlock (&ksocknal_data.ksnd_global_lock);
-        if (rc) {
-                /* Ack cookie is piggybacked */
-                return 0;
-        }
-
-        tx = ksocknal_alloc_tx(KSOCK_NOOP_TX_SIZE);
-        if (tx == NULL) {
-                CERROR("Can't allocate noop tx desc\n");
-                return -ENOMEM;
-        }
-
-        tx->tx_conn     = NULL;
-        tx->tx_lnetmsg  = NULL;
-        tx->tx_kiov     = NULL;
-        tx->tx_nkiov    = 0;
-        tx->tx_iov      = tx->tx_frags.virt.iov;
-        tx->tx_niov     = 1;
-
-        ksocknal_init_msg(&tx->tx_msg, KSOCK_MSG_NOOP);
-        tx->tx_msg.ksm_zc_ack_cookie = cookie; /* incoming cookie */
-
-        cfs_read_lock (&ksocknal_data.ksnd_global_lock);
-
-        conn = ksocknal_find_conn_locked (0, peer);
-        if (conn == NULL) {
-                cfs_read_unlock (&ksocknal_data.ksnd_global_lock);
-                ksocknal_free_tx(tx);
-                CERROR("Can't find connection to send zcack.\n");
-                return -ECONNRESET;
-        }
-        ksocknal_queue_tx_locked(tx, conn);
-
-        cfs_read_unlock (&ksocknal_data.ksnd_global_lock);
-
-        return 0;
-}
-
-/* (Sender) handle ZC_ACK from sink */
-static int
-ksocknal_handle_zc_ack(ksock_peer_t *peer, __u64 cookie)
-{
-        ksock_tx_t             *tx;
-        struct list_head       *ctmp;
-
-        cfs_spin_lock(&peer->ksnp_lock);
-
-        list_for_each(ctmp, &peer->ksnp_zc_req_list) {
-                tx = list_entry (ctmp, ksock_tx_t, tx_zc_list);
-                if (tx->tx_msg.ksm_zc_req_cookie != cookie)
-                        continue;
-
-                tx->tx_msg.ksm_zc_req_cookie = 0;
-                list_del(&tx->tx_zc_list);
-
-                cfs_spin_unlock(&peer->ksnp_lock);
-
-                ksocknal_tx_decref(tx);
-                return 0;
-        }
-        cfs_spin_unlock(&peer->ksnp_lock);
-
-        return -EPROTO;
-}
-
 int
 ksocknal_process_receive (ksock_conn_t *conn)
 {
-        int           rc;
+        lnet_hdr_t        *lhdr;
+        lnet_process_id_t *id;
+        int                rc;
 
         LASSERT (cfs_atomic_read(&conn->ksnc_conn_refcount) > 0);
 
@@ -1294,8 +1137,8 @@ ksocknal_process_receive (ksock_conn_t *conn)
                 if (conn->ksnc_flip) {
                         __swab32s(&conn->ksnc_msg.ksm_type);
                         __swab32s(&conn->ksnc_msg.ksm_csum);
-                        __swab64s(&conn->ksnc_msg.ksm_zc_req_cookie);
-                        __swab64s(&conn->ksnc_msg.ksm_zc_ack_cookie);
+                        __swab64s(&conn->ksnc_msg.ksm_zc_cookies[0]);
+                        __swab64s(&conn->ksnc_msg.ksm_zc_cookies[1]);
                 }
 
                 if (conn->ksnc_msg.ksm_type != KSOCK_MSG_NOOP &&
@@ -1320,15 +1163,21 @@ ksocknal_process_receive (ksock_conn_t *conn)
                         return (-EIO);
                 }
 
-                if (conn->ksnc_msg.ksm_zc_ack_cookie != 0) {
-                        LASSERT(conn->ksnc_proto == &ksocknal_protocol_v2x);
+                if (conn->ksnc_msg.ksm_zc_cookies[1] != 0) {
+                        __u64 cookie = 0;
+
+                        LASSERT (conn->ksnc_proto != &ksocknal_protocol_v1x);
+
+                        if (conn->ksnc_msg.ksm_type == KSOCK_MSG_NOOP)
+                                cookie = conn->ksnc_msg.ksm_zc_cookies[0];
+
+                        rc = conn->ksnc_proto->pro_handle_zcack(conn, cookie,
+                                               conn->ksnc_msg.ksm_zc_cookies[1]);
 
-                        rc = ksocknal_handle_zc_ack(conn->ksnc_peer,
-                                                    conn->ksnc_msg.ksm_zc_ack_cookie);
                         if (rc != 0) {
-                                CERROR("%s: Unknown zero copy ACK cookie: "LPU64"\n",
+                                CERROR("%s: Unknown ZC-ACK cookie: "LPU64", "LPU64"\n",
                                        libcfs_id2str(conn->ksnc_peer->ksnp_id),
-                                       conn->ksnc_msg.ksm_zc_ack_cookie);
+                                       cookie, conn->ksnc_msg.ksm_zc_cookies[1]);
                                 ksocknal_new_packet(conn, 0);
                                 ksocknal_close_conn_and_siblings(conn, -EPROTO);
                                 return (rc);
@@ -1360,8 +1209,8 @@ ksocknal_process_receive (ksock_conn_t *conn)
 
                 if ((conn->ksnc_peer->ksnp_id.pid & LNET_PID_USERFLAG) != 0) {
                         /* Userspace peer */
-                        lnet_process_id_t *id = &conn->ksnc_peer->ksnp_id;
-                        lnet_hdr_t        *lhdr = &conn->ksnc_msg.ksm_u.lnetmsg.ksnm_hdr;
+                        lhdr = &conn->ksnc_msg.ksm_u.lnetmsg.ksnm_hdr;
+                        id   = &conn->ksnc_peer->ksnp_id;
 
                         /* Substitute process ID assigned at connection time */
                         lhdr->src_pid = cpu_to_le32(id->pid);
@@ -1405,14 +1254,19 @@ ksocknal_process_receive (ksock_conn_t *conn)
                         rc = -EIO;
                 }
 
-                lnet_finalize(conn->ksnc_peer->ksnp_ni, conn->ksnc_cookie, rc);
+                if (rc == 0 && conn->ksnc_msg.ksm_zc_cookies[0] != 0) {
+                        LASSERT(conn->ksnc_proto != &ksocknal_protocol_v1x);
+
+                        lhdr = &conn->ksnc_msg.ksm_u.lnetmsg.ksnm_hdr;
+                        id   = &conn->ksnc_peer->ksnp_id;
 
-                if (rc == 0 && conn->ksnc_msg.ksm_zc_req_cookie != 0) {
-                        LASSERT(conn->ksnc_proto == &ksocknal_protocol_v2x);
-                        rc = ksocknal_handle_zc_req(conn->ksnc_peer,
-                                                    conn->ksnc_msg.ksm_zc_req_cookie);
+                        rc = conn->ksnc_proto->pro_handle_zcreq(conn,
+                                               conn->ksnc_msg.ksm_zc_cookies[0],
+                                               le64_to_cpu(lhdr->src_nid) != id->nid);
                 }
 
+                lnet_finalize(conn->ksnc_peer->ksnp_ni, conn->ksnc_cookie, rc);
+
                 if (rc != 0) {
                         ksocknal_new_packet(conn, 0);
                         ksocknal_close_conn_and_siblings (conn, rc);
@@ -1595,8 +1449,8 @@ int ksocknal_scheduler (void *arg)
                         tx = list_entry(conn->ksnc_tx_queue.next,
                                         ksock_tx_t, tx_list);
 
-                        if (conn->ksnc_tx_mono == tx)
-                                ksocknal_next_mono_tx(conn);
+                        if (conn->ksnc_tx_carrier == tx)
+                                ksocknal_next_tx_carrier(conn);
 
                         /* dequeue now so empty list => more to send */
                         list_del(&tx->tx_list);
@@ -1732,15 +1586,29 @@ void ksocknal_write_callback (ksock_conn_t *conn)
 ksock_proto_t *
 ksocknal_parse_proto_version (ksock_hello_msg_t *hello)
 {
-        if ((hello->kshm_magic   == LNET_PROTO_MAGIC &&
-             hello->kshm_version == KSOCK_PROTO_V2) ||
-            (hello->kshm_magic   == __swab32(LNET_PROTO_MAGIC) &&
-             hello->kshm_version == __swab32(KSOCK_PROTO_V2))) {
+        __u32   version = 0;
+
+        if (hello->kshm_magic == LNET_PROTO_MAGIC)
+                version = hello->kshm_version;
+        else if (hello->kshm_magic == __swab32(LNET_PROTO_MAGIC))
+                version = __swab32(hello->kshm_version);
+
+        if (version != 0) {
 #if SOCKNAL_VERSION_DEBUG
-                if (*ksocknal_tunables.ksnd_protocol != 2)
+                if (*ksocknal_tunables.ksnd_protocol == 1)
+                        return NULL;
+
+                if (*ksocknal_tunables.ksnd_protocol == 2 &&
+                    version == KSOCK_PROTO_V3)
                         return NULL;
 #endif
-                return &ksocknal_protocol_v2x;
+                if (version == KSOCK_PROTO_V2)
+                        return &ksocknal_protocol_v2x;
+
+                if (version == KSOCK_PROTO_V3)
+                        return &ksocknal_protocol_v3x;
+
+                return NULL;
         }
 
         if (hello->kshm_magic == le32_to_cpu(LNET_PROTO_TCP_MAGIC)) {
@@ -1757,332 +1625,6 @@ ksocknal_parse_proto_version (ksock_hello_msg_t *hello)
         return NULL;
 }
 
-static int
-ksocknal_send_hello_v1 (ksock_conn_t *conn, ksock_hello_msg_t *hello)
-{
-        cfs_socket_t        *sock = conn->ksnc_sock;
-        lnet_hdr_t          *hdr;
-        lnet_magicversion_t *hmv;
-        int                  rc;
-        int                  i;
-
-        CLASSERT(sizeof(lnet_magicversion_t) == offsetof(lnet_hdr_t, src_nid));
-
-        LIBCFS_ALLOC(hdr, sizeof(*hdr));
-        if (hdr == NULL) {
-                CERROR("Can't allocate lnet_hdr_t\n");
-                return -ENOMEM;
-        }
-
-        hmv = (lnet_magicversion_t *)&hdr->dest_nid;
-
-        /* Re-organize V2.x message header to V1.x (lnet_hdr_t)
-         * header and send out */
-        hmv->magic         = cpu_to_le32 (LNET_PROTO_TCP_MAGIC);
-        hmv->version_major = cpu_to_le16 (KSOCK_PROTO_V1_MAJOR);
-        hmv->version_minor = cpu_to_le16 (KSOCK_PROTO_V1_MINOR);
-
-        if (the_lnet.ln_testprotocompat != 0) {
-                /* single-shot proto check */
-                LNET_LOCK();
-                if ((the_lnet.ln_testprotocompat & 1) != 0) {
-                        hmv->version_major++;   /* just different! */
-                        the_lnet.ln_testprotocompat &= ~1;
-                }
-                if ((the_lnet.ln_testprotocompat & 2) != 0) {
-                        hmv->magic = LNET_PROTO_MAGIC;
-                        the_lnet.ln_testprotocompat &= ~2;
-                }
-                LNET_UNLOCK();
-        }
-
-        hdr->src_nid        = cpu_to_le64 (hello->kshm_src_nid);
-        hdr->src_pid        = cpu_to_le32 (hello->kshm_src_pid);
-        hdr->type           = cpu_to_le32 (LNET_MSG_HELLO);
-        hdr->payload_length = cpu_to_le32 (hello->kshm_nips * sizeof(__u32));
-        hdr->msg.hello.type = cpu_to_le32 (hello->kshm_ctype);
-        hdr->msg.hello.incarnation = cpu_to_le64 (hello->kshm_src_incarnation);
-
-        rc = libcfs_sock_write(sock, hdr, sizeof(*hdr), lnet_acceptor_timeout());
-
-        if (rc != 0) {
-                CDEBUG (D_NETERROR, "Error %d sending HELLO hdr to %u.%u.%u.%u/%d\n",
-                        rc, HIPQUAD(conn->ksnc_ipaddr), conn->ksnc_port);
-                goto out;
-        }
-
-        if (hello->kshm_nips == 0)
-                goto out;
-
-        for (i = 0; i < (int) hello->kshm_nips; i++) {
-                hello->kshm_ips[i] = __cpu_to_le32 (hello->kshm_ips[i]);
-        }
-
-        rc = libcfs_sock_write(sock, hello->kshm_ips,
-                               hello->kshm_nips * sizeof(__u32),
-                               lnet_acceptor_timeout());
-        if (rc != 0) {
-                CDEBUG (D_NETERROR, "Error %d sending HELLO payload (%d)"
-                        " to %u.%u.%u.%u/%d\n", rc, hello->kshm_nips,
-                        HIPQUAD(conn->ksnc_ipaddr), conn->ksnc_port);
-        }
-out:
-        LIBCFS_FREE(hdr, sizeof(*hdr));
-
-        return rc;
-}
-
-static int
-ksocknal_send_hello_v2 (ksock_conn_t *conn, ksock_hello_msg_t *hello)
-{
-        cfs_socket_t   *sock = conn->ksnc_sock;
-        int             rc;
-
-        hello->kshm_magic       = LNET_PROTO_MAGIC;
-        hello->kshm_version     = KSOCK_PROTO_V2;
-
-        if (the_lnet.ln_testprotocompat != 0) {
-                /* single-shot proto check */
-                LNET_LOCK();
-                if ((the_lnet.ln_testprotocompat & 1) != 0) {
-                        hello->kshm_version++;   /* just different! */
-                        the_lnet.ln_testprotocompat &= ~1;
-                }
-                LNET_UNLOCK();
-        }
-
-        rc = libcfs_sock_write(sock, hello, offsetof(ksock_hello_msg_t, kshm_ips),
-                               lnet_acceptor_timeout());
-
-        if (rc != 0) {
-                CDEBUG (D_NETERROR, "Error %d sending HELLO hdr to %u.%u.%u.%u/%d\n",
-                        rc, HIPQUAD(conn->ksnc_ipaddr), conn->ksnc_port);
-                return rc;
-        }
-
-        if (hello->kshm_nips == 0)
-                return 0;
-
-        rc = libcfs_sock_write(sock, hello->kshm_ips,
-                               hello->kshm_nips * sizeof(__u32),
-                               lnet_acceptor_timeout());
-        if (rc != 0) {
-                CDEBUG (D_NETERROR, "Error %d sending HELLO payload (%d)"
-                        " to %u.%u.%u.%u/%d\n", rc, hello->kshm_nips,
-                        HIPQUAD(conn->ksnc_ipaddr), conn->ksnc_port);
-        }
-
-        return rc;
-}
-
-static int
-ksocknal_recv_hello_v1(ksock_conn_t *conn, ksock_hello_msg_t *hello,int timeout)
-{
-        cfs_socket_t        *sock = conn->ksnc_sock;
-        lnet_hdr_t          *hdr;
-        int                  rc;
-        int                  i;
-
-        LIBCFS_ALLOC(hdr, sizeof(*hdr));
-        if (hdr == NULL) {
-                CERROR("Can't allocate lnet_hdr_t\n");
-                return -ENOMEM;
-        }
-
-        rc = libcfs_sock_read(sock, &hdr->src_nid,
-                              sizeof (*hdr) - offsetof (lnet_hdr_t, src_nid),
-                              timeout);
-        if (rc != 0) {
-                CERROR ("Error %d reading rest of HELLO hdr from %u.%u.%u.%u\n",
-                        rc, HIPQUAD(conn->ksnc_ipaddr));
-                LASSERT (rc < 0 && rc != -EALREADY);
-                goto out;
-        }
-
-        /* ...and check we got what we expected */
-        if (hdr->type != cpu_to_le32 (LNET_MSG_HELLO)) {
-                CERROR ("Expecting a HELLO hdr,"
-                        " but got type %d from %u.%u.%u.%u\n",
-                        le32_to_cpu (hdr->type),
-                        HIPQUAD(conn->ksnc_ipaddr));
-                rc = -EPROTO;
-                goto out;
-        }
-
-        hello->kshm_src_nid         = le64_to_cpu (hdr->src_nid);
-        hello->kshm_src_pid         = le32_to_cpu (hdr->src_pid);
-        hello->kshm_src_incarnation = le64_to_cpu (hdr->msg.hello.incarnation);
-        hello->kshm_ctype           = le32_to_cpu (hdr->msg.hello.type);
-        hello->kshm_nips            = le32_to_cpu (hdr->payload_length) /
-                                         sizeof (__u32);
-
-        if (hello->kshm_nips > LNET_MAX_INTERFACES) {
-                CERROR("Bad nips %d from ip %u.%u.%u.%u\n",
-                       hello->kshm_nips, HIPQUAD(conn->ksnc_ipaddr));
-                rc = -EPROTO;
-                goto out;
-        }
-
-        if (hello->kshm_nips == 0)
-                goto out;
-
-        rc = libcfs_sock_read(sock, hello->kshm_ips,
-                              hello->kshm_nips * sizeof(__u32), timeout);
-        if (rc != 0) {
-                CERROR ("Error %d reading IPs from ip %u.%u.%u.%u\n",
-                        rc, HIPQUAD(conn->ksnc_ipaddr));
-                LASSERT (rc < 0 && rc != -EALREADY);
-                goto out;
-        }
-
-        for (i = 0; i < (int) hello->kshm_nips; i++) {
-                hello->kshm_ips[i] = __le32_to_cpu(hello->kshm_ips[i]);
-
-                if (hello->kshm_ips[i] == 0) {
-                        CERROR("Zero IP[%d] from ip %u.%u.%u.%u\n",
-                               i, HIPQUAD(conn->ksnc_ipaddr));
-                        rc = -EPROTO;
-                        break;
-                }
-        }
-out:
-        LIBCFS_FREE(hdr, sizeof(*hdr));
-
-        return rc;
-}
-
-static int
-ksocknal_recv_hello_v2 (ksock_conn_t *conn, ksock_hello_msg_t *hello, int timeout)
-{
-        cfs_socket_t      *sock = conn->ksnc_sock;
-        int                rc;
-        int                i;
-
-        if (hello->kshm_magic == LNET_PROTO_MAGIC)
-                conn->ksnc_flip = 0;
-        else
-                conn->ksnc_flip = 1;
-
-        rc = libcfs_sock_read(sock, &hello->kshm_src_nid,
-                              offsetof(ksock_hello_msg_t, kshm_ips) -
-                                       offsetof(ksock_hello_msg_t, kshm_src_nid),
-                              timeout);
-        if (rc != 0) {
-                CERROR ("Error %d reading HELLO from %u.%u.%u.%u\n",
-                        rc, HIPQUAD(conn->ksnc_ipaddr));
-                LASSERT (rc < 0 && rc != -EALREADY);
-                return rc;
-        }
-
-        if (conn->ksnc_flip) {
-                __swab32s(&hello->kshm_src_pid);
-                __swab64s(&hello->kshm_src_nid);
-                __swab32s(&hello->kshm_dst_pid);
-                __swab64s(&hello->kshm_dst_nid);
-                __swab64s(&hello->kshm_src_incarnation);
-                __swab64s(&hello->kshm_dst_incarnation);
-                __swab32s(&hello->kshm_ctype);
-                __swab32s(&hello->kshm_nips);
-        }
-
-        if (hello->kshm_nips > LNET_MAX_INTERFACES) {
-                CERROR("Bad nips %d from ip %u.%u.%u.%u\n",
-                       hello->kshm_nips, HIPQUAD(conn->ksnc_ipaddr));
-                return -EPROTO;
-        }
-
-        if (hello->kshm_nips == 0)
-                return 0;
-
-        rc = libcfs_sock_read(sock, hello->kshm_ips,
-                              hello->kshm_nips * sizeof(__u32), timeout);
-        if (rc != 0) {
-                CERROR ("Error %d reading IPs from ip %u.%u.%u.%u\n",
-                        rc, HIPQUAD(conn->ksnc_ipaddr));
-                LASSERT (rc < 0 && rc != -EALREADY);
-                return rc;
-        }
-
-        for (i = 0; i < (int) hello->kshm_nips; i++) {
-                if (conn->ksnc_flip)
-                        __swab32s(&hello->kshm_ips[i]);
-
-                if (hello->kshm_ips[i] == 0) {
-                        CERROR("Zero IP[%d] from ip %u.%u.%u.%u\n",
-                               i, HIPQUAD(conn->ksnc_ipaddr));
-                        return -EPROTO;
-                }
-        }
-
-        return 0;
-}
-
-static void
-ksocknal_pack_msg_v1(ksock_tx_t *tx)
-{
-        /* V1.x has no KSOCK_MSG_NOOP */
-        LASSERT(tx->tx_msg.ksm_type != KSOCK_MSG_NOOP);
-        LASSERT(tx->tx_lnetmsg != NULL);
-
-        tx->tx_iov[0].iov_base = (void *)&tx->tx_lnetmsg->msg_hdr;
-        tx->tx_iov[0].iov_len  = sizeof(lnet_hdr_t);
-
-        tx->tx_resid = tx->tx_nob = tx->tx_lnetmsg->msg_len + sizeof(lnet_hdr_t);
-}
-
-static void
-ksocknal_pack_msg_v2(ksock_tx_t *tx)
-{
-        tx->tx_iov[0].iov_base = (void *)&tx->tx_msg;
-
-        if (tx->tx_lnetmsg != NULL) {
-                LASSERT(tx->tx_msg.ksm_type != KSOCK_MSG_NOOP);
-
-                tx->tx_msg.ksm_u.lnetmsg.ksnm_hdr = tx->tx_lnetmsg->msg_hdr;
-                tx->tx_iov[0].iov_len = sizeof(ksock_msg_t);
-                tx->tx_resid = tx->tx_nob = sizeof(ksock_msg_t) + tx->tx_lnetmsg->msg_len;
-        } else {
-                LASSERT(tx->tx_msg.ksm_type == KSOCK_MSG_NOOP);
-
-                tx->tx_iov[0].iov_len = offsetof(ksock_msg_t, ksm_u.lnetmsg.ksnm_hdr);
-                tx->tx_resid = tx->tx_nob = offsetof(ksock_msg_t,  ksm_u.lnetmsg.ksnm_hdr);
-        }
-        /* Don't checksum before start sending, because packet can be piggybacked with ACK */
-}
-
-static void
-ksocknal_unpack_msg_v1(ksock_msg_t *msg)
-{
-        msg->ksm_type           = KSOCK_MSG_LNET;
-        msg->ksm_csum           = 0;
-        msg->ksm_zc_req_cookie  = 0;
-        msg->ksm_zc_ack_cookie  = 0;
-}
-
-static void
-ksocknal_unpack_msg_v2(ksock_msg_t *msg)
-{
-        return;  /* Do nothing */
-}
-
-ksock_proto_t  ksocknal_protocol_v1x =
-{
-        KSOCK_PROTO_V1,
-        ksocknal_send_hello_v1,
-        ksocknal_recv_hello_v1,
-        ksocknal_pack_msg_v1,
-        ksocknal_unpack_msg_v1
-};
-
-ksock_proto_t  ksocknal_protocol_v2x =
-{
-        KSOCK_PROTO_V2,
-        ksocknal_send_hello_v2,
-        ksocknal_recv_hello_v2,
-        ksocknal_pack_msg_v2,
-        ksocknal_unpack_msg_v2
-};
-
 int
 ksocknal_send_hello (lnet_ni_t *ni, ksock_conn_t *conn,
                      lnet_nid_t peer_nid, ksock_hello_msg_t *hello)
@@ -2178,9 +1720,11 @@ ksocknal_recv_hello (lnet_ni_t *ni, ksock_conn_t *conn,
         if (proto == NULL) {
                 if (!active) {
                         /* unknown protocol from peer, tell peer my protocol */
-                        conn->ksnc_proto = &ksocknal_protocol_v2x;
+                        conn->ksnc_proto = &ksocknal_protocol_v3x;
 #if SOCKNAL_VERSION_DEBUG
-                        if (*ksocknal_tunables.ksnd_protocol != 2)
+                        if (*ksocknal_tunables.ksnd_protocol == 2)
+                                conn->ksnc_proto = &ksocknal_protocol_v2x;
+                        else if (*ksocknal_tunables.ksnd_protocol == 1)
                                 conn->ksnc_proto = &ksocknal_protocol_v1x;
 #endif
                         hello->kshm_nips = 0;
@@ -2391,14 +1935,18 @@ ksocknal_connect (ksock_route_t *route)
         if (!list_empty(&peer->ksnp_tx_queue) &&
             peer->ksnp_accepting == 0 &&
             ksocknal_find_connecting_route_locked(peer) == NULL) {
+                ksock_conn_t *conn;
+
                 /* ksnp_tx_queue is queued on a conn on successful
-                 * connection */
-                LASSERT (list_empty (&peer->ksnp_conns));
+                 * connection for V1.x and V2.x */
+                if (!list_empty (&peer->ksnp_conns)) {
+                        conn = list_entry(peer->ksnp_conns.next, ksock_conn_t, ksnc_list);
+                        LASSERT (conn->ksnc_proto == &ksocknal_protocol_v3x);
+                }
 
                 /* take all the blocked packets while I've got the lock and
                  * complete below... */
-                list_add(&zombies, &peer->ksnp_tx_queue);
-                list_del_init(&peer->ksnp_tx_queue);
+                list_splice_init(&peer->ksnp_tx_queue, &zombies);
         }
 
 #if 0           /* irrelevent with only eager routes */
@@ -2615,6 +2163,68 @@ ksocknal_flush_stale_txs(ksock_peer_t *peer)
         ksocknal_txlist_done(peer->ksnp_ni, &stale_txs, 1);
 }
 
+int
+ksocknal_send_keepalive_locked(ksock_peer_t *peer)
+{
+        ksock_sched_t  *sched;
+        ksock_conn_t   *conn;
+        ksock_tx_t     *tx;
+
+        if (list_empty(&peer->ksnp_conns)) /* last_alive will be updated by create_conn */
+                return 0;
+
+        if (peer->ksnp_proto != &ksocknal_protocol_v3x)
+                return 0;
+
+        if (*ksocknal_tunables.ksnd_keepalive <= 0 ||
+            cfs_time_before(cfs_time_current(),
+                            cfs_time_add(peer->ksnp_last_alive,
+                                         cfs_time_seconds(*ksocknal_tunables.ksnd_keepalive))))
+                return 0;
+
+        if (cfs_time_before(cfs_time_current(),
+                            peer->ksnp_send_keepalive))
+                return 0;
+
+        /* retry 10 secs later, so we wouldn't put pressure
+         * on this peer if we failed to send keepalive this time */
+        peer->ksnp_send_keepalive = cfs_time_shift(10);
+
+        conn = ksocknal_find_conn_locked(peer, NULL, 1);
+        if (conn != NULL) {
+                sched = conn->ksnc_scheduler;
+
+                spin_lock_bh (&sched->kss_lock);
+                if (!list_empty(&conn->ksnc_tx_queue)) {
+                        spin_unlock_bh(&sched->kss_lock);
+                        /* there is an queued ACK, don't need keepalive */
+                        return 0;
+                }
+
+                spin_unlock_bh(&sched->kss_lock);
+        }
+
+        read_unlock(&ksocknal_data.ksnd_global_lock);
+
+        /* cookie = 1 is reserved for keepalive PING */
+        tx = ksocknal_alloc_tx_noop(1, 1);
+        if (tx == NULL) {
+                read_lock(&ksocknal_data.ksnd_global_lock);
+                return -ENOMEM;
+        }
+
+        if (ksocknal_launch_packet(peer->ksnp_ni, tx, peer->ksnp_id) == 0) {
+                read_lock(&ksocknal_data.ksnd_global_lock);
+                return 1;
+        }
+
+        ksocknal_free_tx(tx);
+        read_lock(&ksocknal_data.ksnd_global_lock);
+
+        return -EIO;
+}
+
+
 void
 ksocknal_check_peer_timeouts (int idx)
 {
@@ -2631,6 +2241,11 @@ ksocknal_check_peer_timeouts (int idx)
 
         list_for_each (ptmp, peers) {
                 peer = list_entry (ptmp, ksock_peer_t, ksnp_list);
+                if (ksocknal_send_keepalive_locked(peer) != 0) {
+                        read_unlock (&ksocknal_data.ksnd_global_lock);
+                        goto again;
+                }
+
                 conn = ksocknal_find_timed_out_conn (peer);
 
                 if (conn != NULL) {