netfilter: nf_tables: make valid_genid callback mandatory

always call this function, followup patch can use this to
aquire a per-netns transaction log to guard the entire batch
instead of using the nfnl susbsys mutex (which is shared among all
namespaces).

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_api.c

@@ -6591,7 +6591,7 @@ static int nf_tables_abort(struct net *net, struct sk_buff *skb)
 
 static bool nf_tables_valid_genid(struct net *net, u32 genid)
 {
-	return net->nft.base_seq == genid;
+	return genid == 0 || net->nft.base_seq == genid;
 }
 
 static const struct nfnetlink_subsystem nf_tables_subsys = {

net/netfilter/nfnetlink.c

@@ -331,13 +331,13 @@ replay:
 		}
 	}
 
-	if (!ss->commit || !ss->abort) {
+	if (!ss->valid_genid || !ss->commit || !ss->abort) {
 		nfnl_unlock(subsys_id);
 		netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
 		return kfree_skb(skb);
 	}
 
-	if (genid && ss->valid_genid && !ss->valid_genid(net, genid)) {
+	if (!ss->valid_genid(net, genid)) {
 		nfnl_unlock(subsys_id);
 		netlink_ack(oskb, nlh, -ERESTART, NULL);
 		return kfree_skb(skb);