tipc: improve link resiliency when rps is activated

Currently, the TIPC RPS dissector is based only on the incoming packets'
source node address, hence steering all traffic from a node to the same
core. We have seen that this makes the links vulnerable to starvation
and unnecessary resets when we turn down the link tolerance to very low
values.

To reduce the risk of this happening, we exempt probe and probe replies
packets from the convergence to one core per source node. Instead, we do
the opposite, - we try to diverge those packets across as many cores as
possible, by randomizing the flow selector key.

To make such packets identifiable to the dissector, we add a new
'is_keepalive' bit to word 0 of the LINK_PROTOCOL header. This bit is
set both for PROBE and PROBE_REPLY messages, and only for those.

It should be noted that these packets are not part of any flow anyway,
and only constitute a minuscule fraction of all packets sent across a
link. Hence, there is no risk that this will affect overall performance.

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, 6 insertions, 6 deletions

diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index 22aba321282d..9a074776f70b 100644
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -84,11 +84,11 @@ struct flow_dissector_key_ipv6_addrs {
 };
 
 /**
- * struct flow_dissector_key_tipc_addrs:
- * @srcnode: source node address
+ * struct flow_dissector_key_tipc:
+ * @key: source node address combined with selector
  */
-struct flow_dissector_key_tipc_addrs {
-	__be32 srcnode;
+struct flow_dissector_key_tipc {
+	__be32 key;
 };
 
 /**
@@ -100,7 +100,7 @@ struct flow_dissector_key_addrs {
 	union {
 		struct flow_dissector_key_ipv4_addrs v4addrs;
 		struct flow_dissector_key_ipv6_addrs v6addrs;
-		struct flow_dissector_key_tipc_addrs tipcaddrs;
+		struct flow_dissector_key_tipc tipckey;
 	};
 };
 
@@ -192,7 +192,7 @@ enum flow_dissector_key_id {
 	FLOW_DISSECTOR_KEY_PORTS, /* struct flow_dissector_key_ports */
 	FLOW_DISSECTOR_KEY_ICMP, /* struct flow_dissector_key_icmp */
 	FLOW_DISSECTOR_KEY_ETH_ADDRS, /* struct flow_dissector_key_eth_addrs */
-	FLOW_DISSECTOR_KEY_TIPC_ADDRS, /* struct flow_dissector_key_tipc_addrs */
+	FLOW_DISSECTOR_KEY_TIPC, /* struct flow_dissector_key_tipc */
 	FLOW_DISSECTOR_KEY_ARP, /* struct flow_dissector_key_arp */
 	FLOW_DISSECTOR_KEY_VLAN, /* struct flow_dissector_key_flow_vlan */
 	FLOW_DISSECTOR_KEY_FLOW_LABEL, /* struct flow_dissector_key_flow_tags */