tipc: add option to suppress PUBLISH events for pre-existing publications

Currently, when a user is subscribing for binding table publications,
he will receive a PUBLISH event for all already existing matching items
in the binding table.

However, a group socket making a subscriptions doesn't need this initial
status update from the binding table, because it has already scanned it
during the join operation. Worse, the multiplicatory effect of issuing
mutual events for dozens or hundreds group members within a short time
frame put a heavy load on the topology server, with the end result that
scale out operations on a big group tend to take much longer than needed.

We now add a new filter option, TIPC_SUB_NO_STATUS, for topology server
subscriptions, so that this initial avalanche of events is suppressed.
This change, along with the previous commit, significantly improves the
range and speed of group scale out operations.

We keep the new option internal for the tipc driver, at least for now.

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, 2 insertions, 2 deletions

diff --git a/net/tipc/server.c b/net/tipc/server.c
index d60c30342327..950c54cbcf3a 100644
--- a/net/tipc/server.c
+++ b/net/tipc/server.c
@@ -490,7 +490,7 @@ void tipc_conn_terminate(struct tipc_server *s, int conid)
 }
 
 bool tipc_topsrv_kern_subscr(struct net *net, u32 port, u32 type,
-			     u32 lower, u32 upper, int *conid)
+			     u32 filter, u32 lower, u32 upper, int *conid)
 {
 	struct tipc_subscriber *scbr;
 	struct tipc_subscr sub;
@@ -501,7 +501,7 @@ bool tipc_topsrv_kern_subscr(struct net *net, u32 port, u32 type,
 	sub.seq.lower = lower;
 	sub.seq.upper = upper;
 	sub.timeout = TIPC_WAIT_FOREVER;
-	sub.filter = TIPC_SUB_PORTS;
+	sub.filter = filter;
 	*(u32 *)&sub.usr_handle = port;
 
 	con = tipc_alloc_conn(tipc_topsrv(net));