netfilter: nf_flow_table: in flow_offload_lookup, skip entries being deleted

flow_offload_lookup(struct nf_flowtable *flow_table,

		    struct flow_offload_tuple *tuple)

{

	return rhashtable_lookup_fast(&flow_table->rhashtable, tuple,

	struct flow_offload_tuple_rhash *tuplehash;

	struct flow_offload *flow;

	int dir;

	tuplehash = rhashtable_lookup_fast(&flow_table->rhashtable, tuple,

					   nf_flow_offload_rhash_params);

	if (!tuplehash)

		return NULL;

	dir = tuplehash->tuple.dir;

	flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);

	if (flow->flags & (FLOW_OFFLOAD_DYING | FLOW_OFFLOAD_TEARDOWN))

		return NULL;

	return tuplehash;

}

EXPORT_SYMBOL_GPL(flow_offload_lookup);