netfilter: nf_tables: always increment set element count

At this time, set->nelems counter only increments when the set has
a maximum size.

All set elements decrement the counter unconditionally, this is
confusing.

Increment the counter unconditionally to make this symmetrical.
This would also allow changing the set maximum size after set creation
in a later patch.
Signed-off-by: Florian Westphal <fw@strlen.de>

net/netfilter/nf_tables_api.c

@@ -6541,11 +6541,14 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
 		goto err_element_clash;
 	}
 
-	if (!(flags & NFT_SET_ELEM_CATCHALL) && set->size &&
-	    !atomic_add_unless(&set->nelems, 1, set->size + set->ndeact)) {
+	if (!(flags & NFT_SET_ELEM_CATCHALL)) {
+		unsigned int max = set->size ? set->size + set->ndeact : UINT_MAX;
+
+		if (!atomic_add_unless(&set->nelems, 1, max)) {
 			err = -ENFILE;
 			goto err_set_full;
 		}
+	}
 
 	nft_trans_elem(trans) = elem;
 	nft_trans_commit_list_add_tail(ctx->net, trans);