staging: dgap: removes redundant null check and change paramter for dgap_tty_digigetcustombaud()

Null checks in dgap_tty_digigetcustombaud() are already done by
dgap_tty_ioctl() and change "tty" as a paramter of this function
to "ch" and "un".
Signed-off-by: Daeseok Youn <daeseok.youn@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/dgap/dgap.c

@@ -108,7 +108,7 @@ static int dgap_get_modem_info(struct channel_t *ch,
 				unsigned int __user *value);
 static int dgap_tty_digisetcustombaud(struct tty_struct *tty,
 				int __user *new_info);
-static int dgap_tty_digigetcustombaud(struct tty_struct *tty,
+static int dgap_tty_digigetcustombaud(struct channel_t *ch, struct un_t *un,
 				      int __user *retinfo);
 static int dgap_tty_tiocmget(struct tty_struct *tty);
 static int dgap_tty_tiocmset(struct tty_struct *tty, unsigned int set,
@@ -3318,28 +3318,15 @@ static int dgap_tty_digisetedelay(struct channel_t *ch, struct board_t *bd,
  *
  * Ioctl to get the current custom baud rate setting.
  */
-static int dgap_tty_digigetcustombaud(struct tty_struct *tty,
+static int dgap_tty_digigetcustombaud(struct channel_t *ch, struct un_t *un,
 				      int __user *retinfo)
 {
-	struct channel_t *ch;
-	struct un_t *un;
 	int tmp;
 	ulong lock_flags;
 
 	if (!retinfo)
 		return -EFAULT;
 
-	if (!tty || tty->magic != TTY_MAGIC)
-		return -EFAULT;
-
-	un = tty->driver_data;
-	if (!un || un->magic != DGAP_UNIT_MAGIC)
-		return -EFAULT;
-
-	ch = un->un_ch;
-	if (!ch || ch->magic != DGAP_CHANNEL_MAGIC)
-		return -EFAULT;
-
 	memset(&tmp, 0, sizeof(tmp));
 
 	spin_lock_irqsave(&ch->ch_lock, lock_flags);
@@ -4048,7 +4035,7 @@ static int dgap_tty_ioctl(struct tty_struct *tty, unsigned int cmd,
 	case DIGI_GETCUSTOMBAUD:
 		spin_unlock_irqrestore(&ch->ch_lock, lock_flags2);
 		spin_unlock_irqrestore(&bd->bd_lock, lock_flags);
-		return dgap_tty_digigetcustombaud(tty, uarg);
+		return dgap_tty_digigetcustombaud(ch, un, uarg);
 
 	case DIGI_SETCUSTOMBAUD:
 		spin_unlock_irqrestore(&ch->ch_lock, lock_flags2);