netfilter: nf_tables: add helper to unregister chain hooks

This patch adds a helper function to unregister chain hooks in the chain
deletion path. Basically, a code factorization.

The new function is useful in follow-up patches.
Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_api.c

@@ -127,6 +127,15 @@ static void nft_trans_destroy(struct nft_trans *trans)
 	kfree(trans);
 }
 
+static void nf_tables_unregister_hooks(const struct nft_table *table,
+				       const struct nft_chain *chain,
+				       unsigned int hook_nops)
+{
+	if (!(table->flags & NFT_TABLE_F_DORMANT) &&
+	    chain->flags & NFT_BASE_CHAIN)
+		nf_unregister_hooks(nft_base_chain(chain)->ops, hook_nops);
+}
+
 /*
  * Tables
  */
@@ -1157,11 +1166,7 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb,
 	list_add_tail_rcu(&chain->list, &table->chains);
 	return 0;
 err2:
-	if (!(table->flags & NFT_TABLE_F_DORMANT) &&
-	    chain->flags & NFT_BASE_CHAIN) {
-		nf_unregister_hooks(nft_base_chain(chain)->ops,
-				    afi->nops);
-	}
+	nf_tables_unregister_hooks(table, chain, afi->nops);
 err1:
 	nf_tables_chain_destroy(chain);
 	return err;
@@ -3368,11 +3373,9 @@ static int nf_tables_commit(struct sk_buff *skb)
 			break;
 		case NFT_MSG_DELCHAIN:
 			nf_tables_chain_notify(&trans->ctx, NFT_MSG_DELCHAIN);
-			if (!(trans->ctx.table->flags & NFT_TABLE_F_DORMANT) &&
-			    trans->ctx.chain->flags & NFT_BASE_CHAIN) {
-				nf_unregister_hooks(nft_base_chain(trans->ctx.chain)->ops,
+			nf_tables_unregister_hooks(trans->ctx.table,
+						   trans->ctx.chain,
 						   trans->ctx.afi->nops);
-			}
 			break;
 		case NFT_MSG_NEWRULE:
 			nft_rule_clear(trans->ctx.net, nft_trans_rule(trans));
@@ -3495,12 +3498,10 @@ static int nf_tables_abort(struct sk_buff *skb)
 			} else {
 				trans->ctx.table->use--;
 				list_del_rcu(&trans->ctx.chain->list);
-				if (!(trans->ctx.table->flags & NFT_TABLE_F_DORMANT) &&
-				    trans->ctx.chain->flags & NFT_BASE_CHAIN) {
-					nf_unregister_hooks(nft_base_chain(trans->ctx.chain)->ops,
+				nf_tables_unregister_hooks(trans->ctx.table,
+							   trans->ctx.chain,
 							   trans->ctx.afi->nops);
 			}
-			}
 			break;
 		case NFT_MSG_DELCHAIN:
 			trans->ctx.table->use++;