tipc: reduce locking scope during packet reception
[cascardo/linux.git] / net / tipc / link.c
index eaccf45..55b675d 100644 (file)
@@ -76,6 +76,10 @@ static const struct nla_policy tipc_nl_prop_policy[TIPC_NLA_PROP_MAX + 1] = {
        [TIPC_NLA_PROP_WIN]             = { .type = NLA_U32 }
 };
 
+/*
+ * Interval between NACKs when packets arrive out of order
+ */
+#define TIPC_NACK_INTV (TIPC_MIN_LINK_WIN * 2)
 /*
  * Out-of-range value for link session numbers
  */
@@ -123,22 +127,19 @@ static int link_establishing(struct tipc_link *l)
        return l->state == TIPC_LINK_ESTABLISHING;
 }
 
-static void link_handle_out_of_seq_msg(struct tipc_link *link,
-                                      struct sk_buff *skb);
-static void tipc_link_proto_rcv(struct tipc_link *link,
-                               struct sk_buff *skb);
-static void link_state_event(struct tipc_link *l_ptr, u32 event);
+static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
+                              struct sk_buff_head *xmitq);
 static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
                                      u16 rcvgap, int tolerance, int priority,
                                      struct sk_buff_head *xmitq);
 static void link_reset_statistics(struct tipc_link *l_ptr);
 static void link_print(struct tipc_link *l_ptr, const char *str);
-static void tipc_link_sync_xmit(struct tipc_link *l);
+static void tipc_link_build_bcast_sync_msg(struct tipc_link *l,
+                                          struct sk_buff_head *xmitq);
 static void tipc_link_sync_rcv(struct tipc_node *n, struct sk_buff *buf);
 static void tipc_link_input(struct tipc_link *l, struct sk_buff *skb);
 static bool tipc_data_input(struct tipc_link *l, struct sk_buff *skb);
 static bool tipc_link_failover_rcv(struct tipc_link *l, struct sk_buff **skb);
-static void link_activate(struct tipc_link *link);
 
 /*
  *  Simple link routines
@@ -283,6 +284,26 @@ void tipc_link_delete_list(struct net *net, unsigned int bearer_id)
        rcu_read_unlock();
 }
 
+/* tipc_link_build_bcast_sync_msg() - synchronize broadcast link endpoints.
+ *
+ * Give a newly added peer node the sequence number where it should
+ * start receiving and acking broadcast packets.
+ */
+static void tipc_link_build_bcast_sync_msg(struct tipc_link *l,
+                                          struct sk_buff_head *xmitq)
+{
+       struct sk_buff *skb;
+       struct sk_buff_head list;
+
+       skb = tipc_msg_create(BCAST_PROTOCOL, STATE_MSG, INT_H_SIZE,
+                             0, l->addr, link_own_addr(l), 0, 0, 0);
+       if (!skb)
+               return;
+       __skb_queue_head_init(&list);
+       __skb_queue_tail(&list, skb);
+       tipc_link_xmit(l, &list, xmitq);
+}
+
 /**
  * tipc_link_fsm_evt - link finite state machine
  * @l: pointer to link
@@ -295,12 +316,13 @@ static int tipc_link_fsm_evt(struct tipc_link *l, int evt,
        int mtyp = 0, rc = 0;
        struct tipc_link *pl;
        enum {
-               LINK_RESET    = 1,
-               LINK_ACTIVATE = (1 << 1),
-               SND_PROBE     = (1 << 2),
-               SND_STATE     = (1 << 3),
-               SND_RESET     = (1 << 4),
-               SND_ACTIVATE  = (1 << 5)
+               LINK_RESET     = 1,
+               LINK_ACTIVATE  = (1 << 1),
+               SND_PROBE      = (1 << 2),
+               SND_STATE      = (1 << 3),
+               SND_RESET      = (1 << 4),
+               SND_ACTIVATE   = (1 << 5),
+               SND_BCAST_SYNC = (1 << 6)
        } actions = 0;
 
        if (l->exec_mode == TIPC_LINK_BLOCKED)
@@ -352,8 +374,8 @@ static int tipc_link_fsm_evt(struct tipc_link *l, int evt,
                        if (pl && link_probing(pl))
                                break;
                        actions |= LINK_ACTIVATE;
-                       if (l->owner->working_links == 1)
-                               tipc_link_sync_xmit(l);
+                       if (!l->owner->working_links)
+                               actions |= SND_BCAST_SYNC;
                        break;
                case PEER_RESET_EVT:
                        l->state = TIPC_LINK_ESTABLISHING;
@@ -374,8 +396,8 @@ static int tipc_link_fsm_evt(struct tipc_link *l, int evt,
                        if (pl && link_probing(pl))
                                break;
                        actions |= LINK_ACTIVATE;
-                       if (l->owner->working_links == 1)
-                               tipc_link_sync_xmit(l);
+                       if (!l->owner->working_links)
+                               actions |= SND_BCAST_SYNC;
                        break;
                case PEER_RESET_EVT:
                        break;
@@ -408,6 +430,8 @@ static int tipc_link_fsm_evt(struct tipc_link *l, int evt,
        if (actions & (SND_PROBE | SND_STATE | SND_RESET | SND_ACTIVATE))
                tipc_link_build_proto_msg(l, mtyp, actions & SND_PROBE,
                                          0, 0, 0, xmitq);
+       if (actions & SND_BCAST_SYNC)
+               tipc_link_build_bcast_sync_msg(l, xmitq);
        return rc;
 }
 
@@ -605,12 +629,14 @@ void tipc_link_reset(struct tipc_link *l_ptr)
        l_ptr->reasm_buf = NULL;
        l_ptr->rcv_unacked = 0;
        l_ptr->snd_nxt = 1;
+       l_ptr->rcv_nxt = 1;
        l_ptr->silent_intv_cnt = 0;
+       l_ptr->stats.recv_info = 0;
        l_ptr->stale_count = 0;
        link_reset_statistics(l_ptr);
 }
 
-static void link_activate(struct tipc_link *link)
+void tipc_link_activate(struct tipc_link *link)
 {
        struct tipc_node *node = link->owner;
 
@@ -623,36 +649,6 @@ static void link_activate(struct tipc_link *link)
        tipc_bearer_add_dest(node->net, link->bearer_id, link->addr);
 }
 
-/**
- * link_state_event - link finite state machine
- * @l_ptr: pointer to link
- * @event: state machine event to process
- */
-static void link_state_event(struct tipc_link *l, unsigned int evt)
-{
-       int rc;
-       struct sk_buff_head xmitq;
-       struct sk_buff *skb;
-
-       if (l->exec_mode == TIPC_LINK_BLOCKED)
-               return;
-
-       __skb_queue_head_init(&xmitq);
-
-       rc = tipc_link_fsm_evt(l, evt, &xmitq);
-
-       if (rc & TIPC_LINK_UP_EVT)
-               link_activate(l);
-
-       if (rc & TIPC_LINK_DOWN_EVT)
-               tipc_link_reset(l);
-
-       skb = __skb_dequeue(&xmitq);
-       if (!skb)
-               return;
-       tipc_bearer_send(l->owner->net, l->bearer_id, skb, &l->media_addr);
-}
-
 /**
  * __tipc_link_xmit(): same as tipc_link_xmit, but destlink is known & locked
  * @link: link to use
@@ -807,30 +803,6 @@ static int __tipc_link_xmit_skb(struct tipc_link *link, struct sk_buff *skb)
        return __tipc_link_xmit(link->owner->net, link, &head);
 }
 
-/*
- * tipc_link_sync_xmit - synchronize broadcast link endpoints.
- *
- * Give a newly added peer node the sequence number where it should
- * start receiving and acking broadcast packets.
- *
- * Called with node locked
- */
-static void tipc_link_sync_xmit(struct tipc_link *link)
-{
-       struct sk_buff *skb;
-       struct tipc_msg *msg;
-
-       skb = tipc_buf_acquire(INT_H_SIZE);
-       if (!skb)
-               return;
-
-       msg = buf_msg(skb);
-       tipc_msg_init(link_own_addr(link), msg, BCAST_PROTOCOL, STATE_MSG,
-                     INT_H_SIZE, link->addr);
-       msg_set_last_bcast(msg, link->owner->bclink.acked);
-       __tipc_link_xmit_skb(link, skb);
-}
-
 /*
  * tipc_link_sync_rcv - synchronize broadcast link endpoints.
  * Receive the sequence number where we should start receiving and
@@ -881,6 +853,34 @@ void tipc_link_push_packets(struct tipc_link *link)
        link->snd_nxt = seqno;
 }
 
+void tipc_link_advance_backlog(struct tipc_link *l, struct sk_buff_head *xmitq)
+{
+       struct sk_buff *skb, *_skb;
+       struct tipc_msg *hdr;
+       u16 seqno = l->snd_nxt;
+       u16 ack = l->rcv_nxt - 1;
+
+       while (skb_queue_len(&l->transmq) < l->window) {
+               skb = skb_peek(&l->backlogq);
+               if (!skb)
+                       break;
+               _skb = skb_clone(skb, GFP_ATOMIC);
+               if (!_skb)
+                       break;
+               __skb_dequeue(&l->backlogq);
+               hdr = buf_msg(skb);
+               l->backlog[msg_importance(hdr)].len--;
+               __skb_queue_tail(&l->transmq, skb);
+               __skb_queue_tail(xmitq, _skb);
+               msg_set_ack(hdr, ack);
+               msg_set_seqno(hdr, seqno);
+               msg_set_bcast_ack(hdr, l->owner->bclink.last_in);
+               l->rcv_unacked = 0;
+               seqno++;
+       }
+       l->snd_nxt = seqno;
+}
+
 void tipc_link_reset_all(struct tipc_node *node)
 {
        char addr_string[16];
@@ -978,6 +978,41 @@ void tipc_link_retransmit(struct tipc_link *l_ptr, struct sk_buff *skb,
        }
 }
 
+static int tipc_link_retransm(struct tipc_link *l, int retransm,
+                             struct sk_buff_head *xmitq)
+{
+       struct sk_buff *_skb, *skb = skb_peek(&l->transmq);
+       struct tipc_msg *hdr;
+
+       if (!skb)
+               return 0;
+
+       /* Detect repeated retransmit failures on same packet */
+       if (likely(l->last_retransm != buf_seqno(skb))) {
+               l->last_retransm = buf_seqno(skb);
+               l->stale_count = 1;
+       } else if (++l->stale_count > 100) {
+               link_retransmit_failure(l, skb);
+               return TIPC_LINK_DOWN_EVT;
+       }
+       skb_queue_walk(&l->transmq, skb) {
+               if (!retransm)
+                       return 0;
+               hdr = buf_msg(skb);
+               _skb = __pskb_copy(skb, MIN_H_SIZE, GFP_ATOMIC);
+               if (!_skb)
+                       return 0;
+               hdr = buf_msg(_skb);
+               msg_set_ack(hdr, l->rcv_nxt - 1);
+               msg_set_bcast_ack(hdr, l->owner->bclink.last_in);
+               _skb->priority = TC_PRIO_CONTROL;
+               __skb_queue_tail(xmitq, _skb);
+               retransm--;
+               l->stats.retransmitted++;
+       }
+       return 0;
+}
+
 /* link_synch(): check if all packets arrived before the synch
  *               point have been consumed
  * Returns true if the parallel links are synched, otherwise false
@@ -1004,155 +1039,6 @@ synched:
        return true;
 }
 
-static void link_retrieve_defq(struct tipc_link *link,
-                              struct sk_buff_head *list)
-{
-       u16 seq_no;
-
-       if (skb_queue_empty(&link->deferdq))
-               return;
-
-       seq_no = buf_seqno(skb_peek(&link->deferdq));
-       if (seq_no == link->rcv_nxt)
-               skb_queue_splice_tail_init(&link->deferdq, list);
-}
-
-/**
- * tipc_rcv - process TIPC packets/messages arriving from off-node
- * @net: the applicable net namespace
- * @skb: TIPC packet
- * @b_ptr: pointer to bearer message arrived on
- *
- * Invoked with no locks held.  Bearer pointer must point to a valid bearer
- * structure (i.e. cannot be NULL), but bearer can be inactive.
- */
-void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b_ptr)
-{
-       struct tipc_net *tn = net_generic(net, tipc_net_id);
-       struct sk_buff_head head;
-       struct tipc_node *n_ptr;
-       struct tipc_link *l_ptr;
-       struct sk_buff *skb1, *tmp;
-       struct tipc_msg *msg;
-       u16 seq_no;
-       u16 ackd;
-       u32 released;
-
-       skb2list(skb, &head);
-
-       while ((skb = __skb_dequeue(&head))) {
-               /* Ensure message is well-formed */
-               if (unlikely(!tipc_msg_validate(skb)))
-                       goto discard;
-
-               /* Handle arrival of a non-unicast link message */
-               msg = buf_msg(skb);
-               if (unlikely(msg_non_seq(msg))) {
-                       if (msg_user(msg) ==  LINK_CONFIG)
-                               tipc_disc_rcv(net, skb, b_ptr);
-                       else
-                               tipc_bclink_rcv(net, skb);
-                       continue;
-               }
-
-               /* Discard unicast link messages destined for another node */
-               if (unlikely(!msg_short(msg) &&
-                            (msg_destnode(msg) != tn->own_addr)))
-                       goto discard;
-
-               /* Locate neighboring node that sent message */
-               n_ptr = tipc_node_find(net, msg_prevnode(msg));
-               if (unlikely(!n_ptr))
-                       goto discard;
-
-               tipc_node_lock(n_ptr);
-               /* Locate unicast link endpoint that should handle message */
-               l_ptr = n_ptr->links[b_ptr->identity].link;
-               if (unlikely(!l_ptr))
-                       goto unlock;
-
-               /* Is reception of this pkt permitted at the moment ? */
-               if (!tipc_node_filter_skb(n_ptr, msg))
-                       goto unlock;
-
-               /* Validate message sequence number info */
-               seq_no = msg_seqno(msg);
-               ackd = msg_ack(msg);
-
-               /* Release acked messages */
-               if (unlikely(n_ptr->bclink.acked != msg_bcast_ack(msg)))
-                       tipc_bclink_acknowledge(n_ptr, msg_bcast_ack(msg));
-
-               released = 0;
-               skb_queue_walk_safe(&l_ptr->transmq, skb1, tmp) {
-                       if (more(buf_seqno(skb1), ackd))
-                               break;
-                        __skb_unlink(skb1, &l_ptr->transmq);
-                        kfree_skb(skb1);
-                        released = 1;
-               }
-
-               /* Try sending any messages link endpoint has pending */
-               if (unlikely(skb_queue_len(&l_ptr->backlogq)))
-                       tipc_link_push_packets(l_ptr);
-
-               if (released && !skb_queue_empty(&l_ptr->wakeupq))
-                       link_prepare_wakeup(l_ptr);
-
-               /* Process the incoming packet */
-               if (unlikely(!link_working(l_ptr))) {
-                       if (msg_user(msg) == LINK_PROTOCOL) {
-                               tipc_link_proto_rcv(l_ptr, skb);
-                               link_retrieve_defq(l_ptr, &head);
-                               skb = NULL;
-                               goto unlock;
-                       }
-
-                       /* Traffic message. Conditionally activate link */
-                       link_state_event(l_ptr, TRAFFIC_EVT);
-
-                       if (link_working(l_ptr)) {
-                               /* Re-insert buffer in front of queue */
-                               __skb_queue_head(&head, skb);
-                               skb = NULL;
-                               goto unlock;
-                       }
-                       goto unlock;
-               }
-
-               /* Link is now in state TIPC_LINK_WORKING */
-               if (unlikely(seq_no != l_ptr->rcv_nxt)) {
-                       link_handle_out_of_seq_msg(l_ptr, skb);
-                       link_retrieve_defq(l_ptr, &head);
-                       skb = NULL;
-                       goto unlock;
-               }
-               l_ptr->silent_intv_cnt = 0;
-
-               /* Synchronize with parallel link if applicable */
-               if (unlikely((l_ptr->exec_mode == TIPC_LINK_TUNNEL) &&
-                            !msg_dup(msg))) {
-                       if (!link_synch(l_ptr))
-                               goto unlock;
-               }
-               l_ptr->rcv_nxt++;
-               if (unlikely(!skb_queue_empty(&l_ptr->deferdq)))
-                       link_retrieve_defq(l_ptr, &head);
-               if (unlikely(++l_ptr->rcv_unacked >= TIPC_MIN_LINK_WIN)) {
-                       l_ptr->stats.sent_acks++;
-                       tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, 0, 0, 0);
-               }
-               tipc_link_input(l_ptr, skb);
-               skb = NULL;
-unlock:
-               tipc_node_unlock(n_ptr);
-               tipc_node_put(n_ptr);
-discard:
-               if (unlikely(skb))
-                       kfree_skb(skb);
-       }
-}
-
 /* tipc_data_input - deliver data and name distr msgs to upper layer
  *
  * Consumes buffer if message is of right type
@@ -1206,9 +1092,6 @@ static void tipc_link_input(struct tipc_link *link, struct sk_buff *skb)
        struct sk_buff *iskb;
        int pos = 0;
 
-       if (likely(tipc_data_input(link, skb)))
-               return;
-
        switch (msg_user(msg)) {
        case TUNNEL_PROTOCOL:
                if (msg_dup(msg)) {
@@ -1247,6 +1130,110 @@ static void tipc_link_input(struct tipc_link *link, struct sk_buff *skb)
        };
 }
 
+static bool tipc_link_release_pkts(struct tipc_link *l, u16 acked)
+{
+       bool released = false;
+       struct sk_buff *skb, *tmp;
+
+       skb_queue_walk_safe(&l->transmq, skb, tmp) {
+               if (more(buf_seqno(skb), acked))
+                       break;
+               __skb_unlink(skb, &l->transmq);
+               kfree_skb(skb);
+               released = true;
+       }
+       return released;
+}
+
+/* tipc_link_rcv - process TIPC packets/messages arriving from off-node
+ * @link: the link that should handle the message
+ * @skb: TIPC packet
+ * @xmitq: queue to place packets to be sent after this call
+ */
+int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
+                 struct sk_buff_head *xmitq)
+{
+       struct sk_buff_head *arrvq = &l->deferdq;
+       struct sk_buff *tmp;
+       struct tipc_msg *hdr;
+       u16 seqno, rcv_nxt;
+       int rc = 0;
+
+       if (unlikely(!__tipc_skb_queue_sorted(arrvq, skb))) {
+               if (!(skb_queue_len(arrvq) % TIPC_NACK_INTV))
+                       tipc_link_build_proto_msg(l, STATE_MSG, 0,
+                                                 0, 0, 0, xmitq);
+               return rc;
+       }
+
+       skb_queue_walk_safe(arrvq, skb, tmp) {
+               hdr = buf_msg(skb);
+
+               /* Verify and update link state */
+               if (unlikely(msg_user(hdr) == LINK_PROTOCOL)) {
+                       __skb_dequeue(arrvq);
+                       rc |= tipc_link_proto_rcv(l, skb, xmitq);
+                       continue;
+               }
+
+               if (unlikely(!link_working(l))) {
+                       rc |= tipc_link_fsm_evt(l, TRAFFIC_EVT, xmitq);
+                       if (!link_working(l)) {
+                               kfree_skb(__skb_dequeue(arrvq));
+                               return rc;
+                       }
+               }
+
+               l->silent_intv_cnt = 0;
+
+               /* Forward queues and wake up waiting users */
+               if (likely(tipc_link_release_pkts(l, msg_ack(hdr)))) {
+                       tipc_link_advance_backlog(l, xmitq);
+                       if (unlikely(!skb_queue_empty(&l->wakeupq)))
+                               link_prepare_wakeup(l);
+               }
+
+               /* Defer reception if there is a gap in the sequence */
+               seqno = msg_seqno(hdr);
+               rcv_nxt = l->rcv_nxt;
+               if (unlikely(less(rcv_nxt, seqno))) {
+                       l->stats.deferred_recv++;
+                       return rc;
+               }
+
+               __skb_dequeue(arrvq);
+
+               /* Drop if packet already received */
+               if (unlikely(more(rcv_nxt, seqno))) {
+                       l->stats.duplicates++;
+                       kfree_skb(skb);
+                       return rc;
+               }
+
+               /* Synchronize with parallel link if applicable */
+               if (unlikely(l->exec_mode == TIPC_LINK_TUNNEL))
+                       if (!msg_dup(hdr) && !link_synch(l)) {
+                               kfree_skb(skb);
+                               return rc;
+                       }
+
+               /* Packet can be delivered */
+               l->rcv_nxt++;
+               l->stats.recv_info++;
+               if (unlikely(!tipc_data_input(l, skb)))
+                       tipc_link_input(l, skb);
+
+               /* Ack at regular intervals */
+               if (unlikely(++l->rcv_unacked >= TIPC_MIN_LINK_WIN)) {
+                       l->rcv_unacked = 0;
+                       l->stats.sent_acks++;
+                       tipc_link_build_proto_msg(l, STATE_MSG,
+                                                 0, 0, 0, 0, xmitq);
+               }
+       }
+       return rc;
+}
+
 /**
  * tipc_link_defer_pkt - Add out-of-sequence message to deferred reception queue
  *
@@ -1286,41 +1273,6 @@ u32 tipc_link_defer_pkt(struct sk_buff_head *list, struct sk_buff *skb)
        return 1;
 }
 
-/*
- * link_handle_out_of_seq_msg - handle arrival of out-of-sequence packet
- */
-static void link_handle_out_of_seq_msg(struct tipc_link *l_ptr,
-                                      struct sk_buff *buf)
-{
-       u32 seq_no = buf_seqno(buf);
-
-       if (likely(msg_user(buf_msg(buf)) == LINK_PROTOCOL)) {
-               tipc_link_proto_rcv(l_ptr, buf);
-               return;
-       }
-
-       /* Record OOS packet arrival */
-       l_ptr->silent_intv_cnt = 0;
-
-       /*
-        * Discard packet if a duplicate; otherwise add it to deferred queue
-        * and notify peer of gap as per protocol specification
-        */
-       if (less(seq_no, l_ptr->rcv_nxt)) {
-               l_ptr->stats.duplicates++;
-               kfree_skb(buf);
-               return;
-       }
-
-       if (tipc_link_defer_pkt(&l_ptr->deferdq, buf)) {
-               l_ptr->stats.deferred_recv++;
-               if ((skb_queue_len(&l_ptr->deferdq) % TIPC_MIN_LINK_WIN) == 1)
-                       tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, 0, 0, 0);
-       } else {
-               l_ptr->stats.duplicates++;
-       }
-}
-
 /*
  * Send protocol message to the other endpoint.
  */
@@ -1341,119 +1293,6 @@ void tipc_link_proto_xmit(struct tipc_link *l, u32 msg_typ, int probe_msg,
        kfree_skb(skb);
 }
 
-/*
- * Receive protocol message :
- * Note that network plane id propagates through the network, and may
- * change at any time. The node with lowest address rules
- */
-static void tipc_link_proto_rcv(struct tipc_link *l_ptr,
-                               struct sk_buff *buf)
-{
-       u32 rec_gap = 0;
-       u32 msg_tol;
-       struct tipc_msg *msg = buf_msg(buf);
-
-       if (l_ptr->exec_mode == TIPC_LINK_BLOCKED)
-               goto exit;
-
-       if (l_ptr->net_plane != msg_net_plane(msg))
-               if (link_own_addr(l_ptr) > msg_prevnode(msg))
-                       l_ptr->net_plane = msg_net_plane(msg);
-
-       switch (msg_type(msg)) {
-
-       case RESET_MSG:
-               if (!link_probing(l_ptr) &&
-                   (l_ptr->peer_session != WILDCARD_SESSION)) {
-                       if (less_eq(msg_session(msg), l_ptr->peer_session))
-                               break; /* duplicate or old reset: ignore */
-               }
-               link_state_event(l_ptr, RESET_MSG);
-
-               /* fall thru' */
-       case ACTIVATE_MSG:
-               /* Update link settings according other endpoint's values */
-               strcpy((strrchr(l_ptr->name, ':') + 1), (char *)msg_data(msg));
-
-               msg_tol = msg_link_tolerance(msg);
-               if (msg_tol > l_ptr->tolerance)
-                       l_ptr->tolerance = msg_tol;
-
-               if (msg_linkprio(msg) > l_ptr->priority)
-                       l_ptr->priority = msg_linkprio(msg);
-
-               if (l_ptr->mtu > msg_max_pkt(msg))
-                       l_ptr->mtu = msg_max_pkt(msg);
-
-               /* Synchronize broadcast link info, if not done previously */
-               if (!tipc_node_is_up(l_ptr->owner)) {
-                       l_ptr->owner->bclink.last_sent =
-                               l_ptr->owner->bclink.last_in =
-                               msg_last_bcast(msg);
-                       l_ptr->owner->bclink.oos_state = 0;
-               }
-
-               l_ptr->peer_session = msg_session(msg);
-               l_ptr->peer_bearer_id = msg_bearer_id(msg);
-
-               if (!msg_peer_is_up(msg))
-                       tipc_node_fsm_evt(l_ptr->owner, PEER_LOST_CONTACT_EVT);
-               if (msg_type(msg) == ACTIVATE_MSG)
-                       link_state_event(l_ptr, ACTIVATE_MSG);
-               break;
-       case STATE_MSG:
-
-               msg_tol = msg_link_tolerance(msg);
-               if (msg_tol)
-                       l_ptr->tolerance = msg_tol;
-
-               if (msg_linkprio(msg) &&
-                   (msg_linkprio(msg) != l_ptr->priority)) {
-                       pr_info("%s<%s>, priority change %u->%u\n",
-                               link_rst_msg, l_ptr->name,
-                               l_ptr->priority, msg_linkprio(msg));
-                       l_ptr->priority = msg_linkprio(msg);
-                       tipc_link_reset(l_ptr);
-                       break;
-               }
-
-               /* Record reception; force mismatch at next timeout: */
-               l_ptr->silent_intv_cnt = 0;
-
-               link_state_event(l_ptr, TRAFFIC_EVT);
-               l_ptr->stats.recv_states++;
-               if (link_resetting(l_ptr))
-                       break;
-
-               if (less_eq(l_ptr->rcv_nxt, msg_next_sent(msg)))
-                       rec_gap = mod(msg_next_sent(msg) - l_ptr->rcv_nxt);
-
-               if (msg_probe(msg))
-                       l_ptr->stats.recv_probes++;
-
-               /* Protocol message before retransmits, reduce loss risk */
-               if (l_ptr->owner->bclink.recv_permitted)
-                       tipc_bclink_update_link_state(l_ptr->owner,
-                                                     msg_last_bcast(msg));
-
-               if (rec_gap || (msg_probe(msg)))
-                       tipc_link_proto_xmit(l_ptr, STATE_MSG, 0,
-                                            rec_gap, 0, 0);
-
-               if (msg_seq_gap(msg)) {
-                       l_ptr->stats.recv_nacks++;
-                       tipc_link_retransmit(l_ptr, skb_peek(&l_ptr->transmq),
-                                            msg_seq_gap(msg));
-               }
-               if (tipc_link_is_up(l_ptr))
-                       tipc_node_fsm_evt(l_ptr->owner,
-                                         PEER_ESTABL_CONTACT_EVT);
-               break;
-       }
-exit:
-       kfree_skb(buf);
-}
-
 /* tipc_link_build_proto_msg: prepare link protocol message for transmission
  */
 static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
@@ -1727,6 +1566,96 @@ exit:
        return *skb;
 }
 
+/* tipc_link_proto_rcv(): receive link level protocol message :
+ * Note that network plane id propagates through the network, and may
+ * change at any time. The node with lowest numerical id determines
+ * network plane
+ */
+static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
+                              struct sk_buff_head *xmitq)
+{
+       struct tipc_msg *hdr = buf_msg(skb);
+       u16 rcvgap = 0;
+       u16 nacked_gap = msg_seq_gap(hdr);
+       u16 peers_snd_nxt =  msg_next_sent(hdr);
+       u16 peers_tol = msg_link_tolerance(hdr);
+       u16 peers_prio = msg_linkprio(hdr);
+       char *if_name;
+       int rc = 0;
+
+       if (l->exec_mode == TIPC_LINK_BLOCKED)
+               goto exit;
+
+       if (link_own_addr(l) > msg_prevnode(hdr))
+               l->net_plane = msg_net_plane(hdr);
+
+       switch (msg_type(hdr)) {
+       case RESET_MSG:
+
+               /* Ignore duplicate RESET with old session number */
+               if ((less_eq(msg_session(hdr), l->peer_session)) &&
+                   (l->peer_session != WILDCARD_SESSION))
+                       break;
+               /* fall thru' */
+       case ACTIVATE_MSG:
+
+               /* Complete own link name with peer's interface name */
+               if_name =  strrchr(l->name, ':') + 1;
+               if (sizeof(l->name) - (if_name - l->name) <= TIPC_MAX_IF_NAME)
+                       break;
+               if (msg_data_sz(hdr) < TIPC_MAX_IF_NAME)
+                       break;
+               strncpy(if_name, msg_data(hdr), TIPC_MAX_IF_NAME);
+
+               /* Update own tolerance if peer indicates a non-zero value */
+               if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL))
+                       l->tolerance = peers_tol;
+
+               /* Update own priority if peer's priority is higher */
+               if (in_range(peers_prio, l->priority + 1, TIPC_MAX_LINK_PRI))
+                       l->priority = peers_prio;
+
+               l->peer_session = msg_session(hdr);
+               l->peer_bearer_id = msg_bearer_id(hdr);
+               rc = tipc_link_fsm_evt(l, msg_type(hdr), xmitq);
+               if (l->mtu > msg_max_pkt(hdr))
+                       l->mtu = msg_max_pkt(hdr);
+               break;
+       case STATE_MSG:
+               /* Update own tolerance if peer indicates a non-zero value */
+               if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL))
+                       l->tolerance = peers_tol;
+
+               l->silent_intv_cnt = 0;
+               l->stats.recv_states++;
+               if (msg_probe(hdr))
+                       l->stats.recv_probes++;
+               rc = tipc_link_fsm_evt(l, TRAFFIC_EVT, xmitq);
+               if (!tipc_link_is_up(l))
+                       break;
+
+               /* Has peer sent packets we haven't received yet ? */
+               if (more(peers_snd_nxt, l->rcv_nxt))
+                       rcvgap = peers_snd_nxt - l->rcv_nxt;
+               if (rcvgap || (msg_probe(hdr)))
+                       tipc_link_build_proto_msg(l, STATE_MSG, 0, rcvgap,
+                                                 0, l->mtu, xmitq);
+               tipc_link_release_pkts(l, msg_ack(hdr));
+
+               /* If NACK, retransmit will now start at right position */
+               if (nacked_gap) {
+                       rc |= tipc_link_retransm(l, nacked_gap, xmitq);
+                       l->stats.recv_nacks++;
+               }
+               tipc_link_advance_backlog(l, xmitq);
+               if (unlikely(!skb_queue_empty(&l->wakeupq)))
+                       link_prepare_wakeup(l);
+       }
+exit:
+       kfree_skb(skb);
+       return rc;
+}
+
 void tipc_link_set_queue_limits(struct tipc_link *l, u32 win)
 {
        int max_bulk = TIPC_MAX_PUBLICATIONS / (l->mtu / ITEM_SIZE);