tipc: Flush unsent broadcast messages when contact with last node is …

…lost

Adds code to release any unsent broadcast messages in the broadcast link
transmit queue if TIPC loses contact with its only neighboring node.
Previously, a broadcast link that was in the congested state would hold
on to the unsent messages, even though the messages were now undeliverable.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

net/tipc/bcast.c

@@ -252,7 +252,17 @@ void tipc_bclink_acknowledge(struct tipc_node *n_ptr, u32 acked)
 
 	while (crs && less_eq(buf_seqno(crs), acked)) {
 		next = crs->next;
-		bcbuf_decr_acks(crs);
+
+		if (crs != bcl->next_out)
+			bcbuf_decr_acks(crs);
+		else if (bclink->bcast_nodes.count)
+			break;
+		else {
+			bcbuf_set_acks(crs, 0);
+			bcl->next_out = next;
+			bclink_set_last_sent();
+		}
+
 		if (bcbuf_acks(crs) == 0) {
 			bcl->first_out = next;
 			bcl->out_queue_size--;