net/netfilter/x_tables.c: use __seq_open_private()

Reduce boilerplate code by using __seq_open_private() instead of seq_open()
in xt_match_open() and xt_target_open().

Signed-off-by: Rob Jones <rob.jones@codethink.co.uk>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/x_tables.c

@@ -1101,22 +1101,11 @@ static const struct seq_operations xt_match_seq_ops = {
 
 static int xt_match_open(struct inode *inode, struct file *file)
 {
-	struct seq_file *seq;
 	struct nf_mttg_trav *trav;
-	int ret;
-
-	trav = kmalloc(sizeof(*trav), GFP_KERNEL);
-	if (trav == NULL)
+	trav = __seq_open_private(file, &xt_match_seq_ops, sizeof(*trav));
+	if (!trav)
 		return -ENOMEM;
 
-	ret = seq_open(file, &xt_match_seq_ops);
-	if (ret < 0) {
-		kfree(trav);
-		return ret;
-	}
-
-	seq = file->private_data;
-	seq->private = trav;
 	trav->nfproto = (unsigned long)PDE_DATA(inode);
 	return 0;
 }
@@ -1165,22 +1154,11 @@ static const struct seq_operations xt_target_seq_ops = {
 
 static int xt_target_open(struct inode *inode, struct file *file)
 {
-	struct seq_file *seq;
 	struct nf_mttg_trav *trav;
-	int ret;
-
-	trav = kmalloc(sizeof(*trav), GFP_KERNEL);
-	if (trav == NULL)
+	trav = __seq_open_private(file, &xt_target_seq_ops, sizeof(*trav));
+	if (!trav)
 		return -ENOMEM;
 
-	ret = seq_open(file, &xt_target_seq_ops);
-	if (ret < 0) {
-		kfree(trav);
-		return ret;
-	}
-
-	seq = file->private_data;
-	seq->private = trav;
 	trav->nfproto = (unsigned long)PDE_DATA(inode);
 	return 0;
 }