netfilter: nf_tables: add nft_set_elem_update_expr() helper function

This helper function runs the eval path of the stateful expression
of an existing set element.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_tables.h

@@ -890,6 +890,18 @@ static inline struct nft_userdata *nft_userdata(const struct nft_rule *rule)
 	return (void *)&rule->data[rule->dlen];
 }
 
+static inline void nft_set_elem_update_expr(const struct nft_set_ext *ext,
+					    struct nft_regs *regs,
+					    const struct nft_pktinfo *pkt)
+{
+	struct nft_expr *expr;
+
+	if (nft_set_ext_exists(ext, NFT_SET_EXT_EXPR)) {
+		expr = nft_set_ext_expr(ext);
+		expr->ops->eval(expr, regs, pkt);
+	}
+}
+
 /*
  * The last pointer isn't really necessary, but the compiler isn't able to
  * determine that the result of nft_expr_last() is always the same since it

net/netfilter/nft_dynset.c

@@ -81,7 +81,6 @@ void nft_dynset_eval(const struct nft_expr *expr,
 	const struct nft_dynset *priv = nft_expr_priv(expr);
 	struct nft_set *set = priv->set;
 	const struct nft_set_ext *ext;
-	const struct nft_expr *sexpr;
 	u64 timeout;
 
 	if (priv->op == NFT_DYNSET_OP_DELETE) {
@@ -91,18 +90,13 @@ void nft_dynset_eval(const struct nft_expr *expr,
 
 	if (set->ops->update(set, &regs->data[priv->sreg_key], nft_dynset_new,
 			     expr, regs, &ext)) {
-		sexpr = NULL;
-		if (nft_set_ext_exists(ext, NFT_SET_EXT_EXPR))
-			sexpr = nft_set_ext_expr(ext);
-
 		if (priv->op == NFT_DYNSET_OP_UPDATE &&
 		    nft_set_ext_exists(ext, NFT_SET_EXT_EXPIRATION)) {
 			timeout = priv->timeout ? : set->timeout;
 			*nft_set_ext_expiration(ext) = get_jiffies_64() + timeout;
 		}
 
-		if (sexpr != NULL)
-			sexpr->ops->eval(sexpr, regs, pkt);
+		nft_set_elem_update_expr(ext, regs, pkt);
 
 		if (priv->invert)
 			regs->verdict.code = NFT_BREAK;