tipc: make replicast a user selectable option

If the bearer carrying multicast messages supports broadcast, those
messages will be sent to all cluster nodes, irrespective of whether
these nodes host any actual destinations socket or not. This is clearly
wasteful if the cluster is large and there are only a few real
destinations for the message being sent.

In this commit we extend the eligibility of the newly introduced
"replicast" transmit option. We now make it possible for a user to
select which method he wants to be used, either as a mandatory setting
via setsockopt(), or as a relative setting where we let the broadcast
layer decide which method to use based on the ratio between cluster
size and the message's actual number of destination nodes.

In the latter case, a sending socket must stick to a previously
selected method until it enters an idle period of at least 5 seconds.
This eliminates the risk of message reordering caused by method change,
i.e., when changes to cluster size or number of destinations would
otherwise mandate a new method to be used.

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, 16 insertions, 1 deletions

diff --git a/net/tipc/bcast.h b/net/tipc/bcast.h
index dd772e6f6fa4..751530ab0c49 100644
--- a/net/tipc/bcast.h
+++ b/net/tipc/bcast.h
@@ -46,6 +46,8 @@ struct tipc_nlist;
 struct tipc_nitem;
 extern const char tipc_bclink_name[];
 
+#define TIPC_METHOD_EXPIRE msecs_to_jiffies(5000)
+
 struct tipc_nlist {
 	struct list_head list;
 	u32 self;
@@ -58,6 +60,17 @@ void tipc_nlist_purge(struct tipc_nlist *nl);
 void tipc_nlist_add(struct tipc_nlist *nl, u32 node);
 void tipc_nlist_del(struct tipc_nlist *nl, u32 node);
 
+/* Cookie to be used between socket and broadcast layer
+ * @rcast: replicast (instead of broadcast) was used at previous xmit
+ * @mandatory: broadcast/replicast indication was set by user
+ * @expires: re-evaluate non-mandatory transmit method if we are past this
+ */
+struct tipc_mc_method {
+	bool rcast;
+	bool mandatory;
+	unsigned long expires;
+};
+
 int tipc_bcast_init(struct net *net);
 void tipc_bcast_stop(struct net *net);
 void tipc_bcast_add_peer(struct net *net, struct tipc_link *l,
@@ -66,8 +79,10 @@ void tipc_bcast_remove_peer(struct net *net, struct tipc_link *rcv_bcl);
 void tipc_bcast_inc_bearer_dst_cnt(struct net *net, int bearer_id);
 void tipc_bcast_dec_bearer_dst_cnt(struct net *net, int bearer_id);
 int  tipc_bcast_get_mtu(struct net *net);
+void tipc_bcast_disable_rcast(struct net *net);
 int tipc_mcast_xmit(struct net *net, struct sk_buff_head *pkts,
-		    struct tipc_nlist *dests, u16 *cong_link_cnt);
+		    struct tipc_mc_method *method, struct tipc_nlist *dests,
+		    u16 *cong_link_cnt);
 int tipc_bcast_rcv(struct net *net, struct tipc_link *l, struct sk_buff *skb);
 void tipc_bcast_ack_rcv(struct net *net, struct tipc_link *l,
 			struct tipc_msg *hdr);