isdn: use simple_read_from_buffer()

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Karsten Keil <kkeil@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/isdn/hysdn/hysdn_procconf.c

@@ -207,30 +207,17 @@ hysdn_conf_write(struct file *file, const char __user *buf, size_t count, loff_t
 /* read conf file -> output card info data */
 /*******************************************/
 static ssize_t
-hysdn_conf_read(struct file *file, char __user *buf, size_t count, loff_t * off)
+hysdn_conf_read(struct file *file, char __user *buf, size_t count, loff_t *off)
 {
 	char *cp;
-	int i;
 
-	if (file->f_mode & FMODE_READ) {
+	if (!(file->f_mode & FMODE_READ))
+		return -EPERM;	/* no permission to read */
+
 	if (!(cp = file->private_data))
-			return (-EFAULT);	/* should never happen */
-		i = strlen(cp);	/* get total string length */
-		if (*off < i) {
-			/* still bytes to transfer */
-			cp += *off;	/* point to desired data offset */
-			i -= *off;	/* remaining length */
-			if (i > count)
-				i = count;	/* limit length to transfer */
-			if (copy_to_user(buf, cp, i))
-				return (-EFAULT);	/* copy error */
-			*off += i;	/* adjust offset */
-		} else
-			return (0);
-	} else
-		return (-EPERM);	/* no permission to read */
+		return -EFAULT;	/* should never happen */
 
-	return (i);
+	return simple_read_from_buffer(buf, count, off, cp, strlen(cp));
 }				/* hysdn_conf_read */
 
 /******************/