netfilter: nft_set_pipapo: Use struct_size()

Use struct_size() instead of hand writing it.
This is less verbose and more informative.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Florian Westphal <fw@strlen.de>

net/netfilter/nft_set_pipapo.c

@@ -1274,8 +1274,7 @@ static struct nft_pipapo_match *pipapo_clone(struct nft_pipapo_match *old)
 	struct nft_pipapo_match *new;
 	int i;
 
-	new = kmalloc(sizeof(*new) + sizeof(*dst) * old->field_count,
-		      GFP_KERNEL);
+	new = kmalloc(struct_size(new, f, old->field_count), GFP_KERNEL);
 	if (!new)
 		return ERR_PTR(-ENOMEM);
 
@@ -2059,8 +2058,7 @@ static int nft_pipapo_init(const struct nft_set *set,
 	if (field_count > NFT_PIPAPO_MAX_FIELDS)
 		return -EINVAL;
 
-	m = kmalloc(sizeof(*priv->match) + sizeof(*f) * field_count,
-		    GFP_KERNEL);
+	m = kmalloc(struct_size(m, f, field_count), GFP_KERNEL);
 	if (!m)
 		return -ENOMEM;