From fa36882682db0692ecbea20f859180f978923d72 Mon Sep 17 00:00:00 2001 From: Jon Maloy Date: Thu, 2 Nov 2017 15:44:15 +0100 Subject: [PATCH] tipc: eliminate unnecessary probing The neighbor monitor employs a threshold, default set to 32 peer nodes, where it activates the "Overlapping Neighbor Monitoring" algorithm. Below that threshold, monitoring is full-mesh, and no "domain records" are passed between the nodes. Because of this, a node never received a peer's ack that it has received the most recent update of the own domain. Hence, the field 'acked_gen' in struct tipc_monitor_state remains permamently at zero, whereas the own domain generation is incremented for each added or removed peer. This has the effect that the function tipc_mon_get_state() always sets the field 'probing' in struct tipc_monitor_state true, again leading the tipc_link_timeout() of the link in question to always send out a probe, even when link->silent_intv_count is zero. This is functionally harmless, but leads to some unncessary probing, which can easily be eliminated by setting the 'probing' field of the said struct correctly in such cases. At the same time, we explictly invalidate the sent domain records when the algorithm is not activated. This will eliminate any risk that an invalid domain record might be inadverently accepted by the peer. Signed-off-by: Jon Maloy Signed-off-by: David S. Miller --- net/tipc/monitor.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/net/tipc/monitor.c b/net/tipc/monitor.c index b9c32557d73c..8e884ed06d4b 100644 --- a/net/tipc/monitor.c +++ b/net/tipc/monitor.c @@ -530,8 +530,11 @@ void tipc_mon_prep(struct net *net, void *data, int *dlen, u16 gen = mon->dom_gen; u16 len; - if (!tipc_mon_is_active(net, mon)) + /* Send invalid record if not active */ + if (!tipc_mon_is_active(net, mon)) { + dom->len = 0; return; + } /* Send only a dummy record with ack if peer has acked our last sent */ if (likely(state->acked_gen == gen)) { @@ -559,6 +562,12 @@ void tipc_mon_get_state(struct net *net, u32 addr, struct tipc_monitor *mon = tipc_monitor(net, bearer_id); struct tipc_peer *peer; + if (!tipc_mon_is_active(net, mon)) { + state->probing = false; + state->monitoring = true; + return; + } + /* Used cached state if table has not changed */ if (!state->probing && (state->list_gen == mon->list_gen) &&