tipc: interrupt link synchronization when a link goes down

When we introduced the new link failover/synch mechanism
in commit 6e498158a827fd515b514842e9a06bdf0f75ab86
("tipc: move link synch and failover to link aggregation level"),
we missed the case when the non-tunnel link goes down during the link
synchronization period. In this case the tunnel link will remain in
state LINK_SYNCHING, something leading to unpredictable behavior when
the failover procedure is initiated.

In this commit, we ensure that the node and remaining link goes
back to regular communication state (SELF_UP_PEER_UP/LINK_ESTABLISHED)
when one of the parallel links goes down. We also ensure that we don't
re-enter synch mode if subsequent SYNCH packets arrive on the remaining
link.

Reviewed-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/tipc/link.c b/net/tipc/link.c
index f067e54..7058c86 100644 (file)
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -351,11 +351,11 @@ int tipc_link_fsm_evt(struct tipc_link *l, int evt)
                        l->state = LINK_RESET;
                        break;
                case LINK_ESTABLISH_EVT:
+               case LINK_SYNCH_END_EVT:
                        break;
                case LINK_SYNCH_BEGIN_EVT:
                        l->state = LINK_SYNCHING;
                        break;
-               case LINK_SYNCH_END_EVT:
                case LINK_FAILOVER_BEGIN_EVT:
                case LINK_FAILOVER_END_EVT:
                default:

diff --git a/net/tipc/node.c b/net/tipc/node.c
index 004834b..937cc61 100644 (file)
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -423,6 +423,8 @@ static void __tipc_node_link_down(struct tipc_node *n, int *bearer_id,
 
        /* There is still a working link => initiate failover */
        tnl = node_active_link(n, 0);
+       tipc_link_fsm_evt(tnl, LINK_SYNCH_END_EVT);
+       tipc_node_fsm_evt(n, NODE_SYNCH_END_EVT);
        n->sync_point = tnl->rcv_nxt + (U16_MAX / 2 - 1);
        tipc_link_tnl_prepare(l, tnl, FAILOVER_MSG, xmitq);
        tipc_link_reset(l);
@@ -1140,6 +1142,10 @@ static bool tipc_node_check_state(struct tipc_node *n, struct sk_buff *skb,
                return true;
        }
 
+       /* No synching needed if only one link */
+       if (!pl || !tipc_link_is_up(pl))
+               return true;
+
        /* Initiate or update synch mode if applicable */
        if ((usr == TUNNEL_PROTOCOL) && (mtyp == SYNCH_MSG)) {
                syncpt = iseqno + exp_pkts - 1;
@@ -1158,9 +1164,8 @@ static bool tipc_node_check_state(struct tipc_node *n, struct sk_buff *skb,
 
        /* Open tunnel link when parallel link reaches synch point */
        if ((n->state == NODE_SYNCHING) && tipc_link_is_synching(l)) {
-               if (pl)
-                       dlv_nxt = mod(pl->rcv_nxt - skb_queue_len(pl->inputq));
-               if (!pl || more(dlv_nxt, n->sync_point)) {
+               dlv_nxt = pl->rcv_nxt - mod(skb_queue_len(pl->inputq));
+               if (more(dlv_nxt, n->sync_point)) {
                        tipc_link_fsm_evt(l, LINK_SYNCH_END_EVT);
                        tipc_node_fsm_evt(n, NODE_SYNCH_END_EVT);
                        return true;