mlxsw: spectrum_router: Don't read 'nud_state' without lock

We periodically ask the neighbouring system to try and resolve
neighbours that are used for nexthops, but aren't currently resolved.

However, 'nud_state' is protected by the neighbour lock, so we shouldn't
access it without taking it. Instead, we can simply check the
'connected' field of the neighbour entry, which we update upon
NEIGH_UPDATE events.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c

@@ -896,7 +896,7 @@ static void mlxsw_sp_router_probe_unresolved_nexthops(struct work_struct *work)
 	rtnl_lock();
 	list_for_each_entry(neigh_entry, &mlxsw_sp->router.nexthop_neighs_list,
 			    nexthop_neighs_list_node)
-		if (!(neigh_entry->key.n->nud_state & NUD_VALID))
+		if (!neigh_entry->connected)
 			neigh_event_send(neigh_entry->key.n, NULL);
 	rtnl_unlock();