tipc: don't reset stale broadcast send link

When the broadcast send link after 100 attempts has failed to
transfer a packet to all peers, we consider it stale, and reset
it. Thereafter it needs to re-synchronize with the peers, something
currently done by just resetting and re-establishing all links to
all peers. This has turned out to be overkill, with potentially
unwanted consequences for the remaining cluster.

A closer analysis reveals that this can be done much simpler. When
this kind of failure happens, for reasons that may lie outside the
TIPC protocol, it is typically only one peer which is failing to
receive and acknowledge packets. It is hence sufficient to identify
and reset the links only to that peer to resolve the situation, without
having to reset the broadcast link at all. This solution entails a much
lower risk of negative consequences for the own node as well as for
the overall cluster.

We implement this change in this commit.

Reviewed-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com>
Acked-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>

1 files changed, 4 insertions, 10 deletions

diff --git a/net/tipc/node.c b/net/tipc/node.c
index 9b4dcb6a16b5..eb728397c810 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -1284,7 +1284,7 @@ static void tipc_node_bc_sync_rcv(struct tipc_node *n, struct tipc_msg *hdr,
 	rc = tipc_bcast_sync_rcv(n->net, n->bc_entry.link, hdr);
 
 	if (rc & TIPC_LINK_DOWN_EVT) {
-		tipc_bearer_reset_all(n->net);
+		tipc_node_reset_links(n);
 		return;
 	}
 
@@ -1351,15 +1351,9 @@ static void tipc_node_bc_rcv(struct net *net, struct sk_buff *skb, int bearer_id
 	if (!skb_queue_empty(&be->inputq1))
 		tipc_node_mcast_rcv(n);
 
-	if (rc & TIPC_LINK_DOWN_EVT) {
-		/* Reception reassembly failure => reset all links to peer */
-		if (!tipc_link_is_up(be->link))
-			tipc_node_reset_links(n);
-
-		/* Retransmission failure => reset all links to all peers */
-		if (!tipc_link_is_up(tipc_bc_sndlink(net)))
-			tipc_bearer_reset_all(net);
-	}
+	/* If reassembly or retransmission failure => reset all links to peer */
+	if (rc & TIPC_LINK_DOWN_EVT)
+		tipc_node_reset_links(n);
 
 	tipc_node_put(n);
 }