neigh: probe application via netlink in NUD_PROBE

iproute2 arpd seems to expect this as there's code and comments
to handle netlink probes with NUD_PROBE set. It is used to flush
the arpd cached mappings.

opennhrp instead turns off unicast probes (so it can handle all
neighbour discovery). Without this change it will not see NUD_PROBE
probes and cannot reconfirm the mapping. Thus currently neigh entry
will just fail and can cause few packets dropped until broadcast
discovery is restarted.

Earlier discussion on the subject:
http://marc.info/?t=139305877100001&r=1&w=2

Signed-off-by: Timo Teräs <timo.teras@iki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index b9e9e0d38672a8ca9a17f8d6ec8daf88b8a09a65..36d3f8c1a2dd85f49aad107cf6ea8aec97ee3c0c 100644 (file)
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -836,10 +836,10 @@ out:
 static __inline__ int neigh_max_probes(struct neighbour *n)
 {
        struct neigh_parms *p = n->parms;
-       return (n->nud_state & NUD_PROBE) ?
-               NEIGH_VAR(p, UCAST_PROBES) :
-               NEIGH_VAR(p, UCAST_PROBES) + NEIGH_VAR(p, APP_PROBES) +
-               NEIGH_VAR(p, MCAST_PROBES);
+       int max_probes = NEIGH_VAR(p, UCAST_PROBES) + NEIGH_VAR(p, APP_PROBES);
+       if (!(n->nud_state & NUD_PROBE))
+               max_probes += NEIGH_VAR(p, MCAST_PROBES);
+       return max_probes;
 }
 
 static void neigh_invalidate(struct neighbour *neigh)