diff -pNaru5 a/driver/2.6.27/dgnc_cls.c b/driver/2.6.27/dgnc_cls.c
--- a/driver/2.6.27/dgnc_cls.c	2017-10-21 10:39:21.000000000 -0400
+++ b/driver/2.6.27/dgnc_cls.c	2023-01-28 14:36:56.298578571 -0500
@@ -482,11 +482,11 @@ static void cls_param(struct tty_struct
 	int quot = 0;
         struct board_t *bd;
 	struct channel_t *ch;
         struct un_t   *un;
 
-	if (!tty || tty->magic != TTY_MAGIC) {
+	if (!tty || !tty->ldisc) {
 		return;
 	}
 
 	un = (struct un_t *) tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC) {
@@ -979,11 +979,11 @@ static int cls_drain(struct tty_struct *
 	ulong lock_flags;
 	struct channel_t *ch;
         struct un_t *un;
 	int rc = 0;
 
-	if (!tty || tty->magic != TTY_MAGIC) {
+	if (!tty || !tty->ldisc) {
 		return (-ENXIO);
 	}
 
 	un = (struct un_t *) tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC) {
diff -pNaru5 a/driver/2.6.27/dgnc_neo.c b/driver/2.6.27/dgnc_neo.c
--- a/driver/2.6.27/dgnc_neo.c	2017-10-21 10:39:21.000000000 -0400
+++ b/driver/2.6.27/dgnc_neo.c	2023-01-28 14:36:49.068942864 -0500
@@ -656,11 +656,11 @@ static void neo_param(struct tty_struct
 	int quot = 0;
         struct board_t *bd;
 	struct channel_t *ch;
         struct un_t   *un;
 
-	if (!tty || tty->magic != TTY_MAGIC) {
+	if (!tty || !tty->ldisc) {
 		return;
 	}
 
 	un = (struct un_t *) tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC) {
@@ -1432,11 +1432,11 @@ static int neo_drain(struct tty_struct *
 	ulong lock_flags;
 	struct channel_t *ch;
         struct un_t *un;
 	int rc = 0;
 
-	if (!tty || tty->magic != TTY_MAGIC) {
+	if (!tty || !tty->ldisc) {
 		return (-ENXIO);
 	}
 
 	un = (struct un_t *) tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC) {
diff -pNaru5 a/driver/2.6.27/dgnc_neo_II.c b/driver/2.6.27/dgnc_neo_II.c
--- a/driver/2.6.27/dgnc_neo_II.c	2017-10-21 10:39:21.000000000 -0400
+++ b/driver/2.6.27/dgnc_neo_II.c	2023-01-28 14:37:01.024996046 -0500
@@ -531,11 +531,11 @@ static void neo_II_param(struct tty_stru
 	int quot = 0;
         struct board_t *bd;
 	struct channel_t *ch;
         struct un_t   *un;
 
-	if (!tty || tty->magic != TTY_MAGIC) {
+	if (!tty || !tty->ldisc) {
 		return;
 	}
 
 	un = (struct un_t *) tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC) {
@@ -1166,11 +1166,11 @@ static int neo_II_drain(struct tty_struc
 	ulong lock_flags;
 	struct channel_t *ch;
         struct un_t *un;
 	int rc = 0;
 
-	if (!tty || tty->magic != TTY_MAGIC) {
+	if (!tty || !tty->ldisc) {
 		return (-ENXIO);
 	}
 
 	un = (struct un_t *) tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC) {
diff -pNaru5 a/driver/2.6.27/dgnc_tty.c b/driver/2.6.27/dgnc_tty.c
--- a/driver/2.6.27/dgnc_tty.c	2023-01-28 14:28:53.575256967 -0500
+++ b/driver/2.6.27/dgnc_tty.c	2023-01-28 14:36:29.533153640 -0500
@@ -783,18 +783,18 @@ void dgnc_input(struct channel_t *ch)
 
 #if LINUX_VERSION_CODE < KERNEL_VERSION(3,7,0)
 	if (!tp || (tp->magic != TTY_MAGIC) || !(ch->ch_tun.un_flags & UN_ISOPEN) || 
 	    !(tp->termios->c_cflag & CREAD) || (ch->ch_tun.un_flags & UN_CLOSING))
 #else
-        if (!tp  || (tp->magic != TTY_MAGIC) || !(ch->ch_tun.un_flags & UN_ISOPEN) ||
+        if (!tp  || !tp->ldisc || !(ch->ch_tun.un_flags & UN_ISOPEN) ||
 	    !(tp->termios.c_cflag & CREAD) || (ch->ch_tun.un_flags & UN_CLOSING))
 #endif
 	{
 
 		DPR_READ(("input. dropping %d bytes on port %d...\n", data_len, ch->ch_portnum));
-		DPR_READ(("input. tp: %p tp->magic: %x MAGIC:%x ch flags: %x\n",
-			tp, tp ? tp->magic : 0, TTY_MAGIC, ch->ch_tun.un_flags));
+		DPR_READ(("input. tp: %p ch flags: %x\n",
+			tp, ch->ch_tun.un_flags));
 
 		ch->ch_r_head = tail;
 
 		/* Force queue flow control to be released, if needed */
 		dgnc_check_queue_flow_control(ch);
@@ -1686,11 +1686,11 @@ static int dgnc_block_til_ready(struct t
 	struct un_t *un = NULL;
 	ulong   lock_flags;
 	uint	old_flags = 0;
 	int	sleep_on_un_flags = 0;
 
-	if (!tty || tty->magic != TTY_MAGIC || !file || !ch || ch->magic != DGNC_CHANNEL_MAGIC) {
+	if (!tty || !tty->ldisc || !file || !ch || ch->magic != DGNC_CHANNEL_MAGIC) {
 		return (-ENXIO);
 	}
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC) {
@@ -1848,11 +1848,11 @@ static int dgnc_block_til_ready(struct t
  */     
 static void dgnc_tty_hangup(struct tty_struct *tty)
 {
 	struct un_t	*un;
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return;
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return;
@@ -1879,11 +1879,11 @@ static void dgnc_tty_close(struct tty_st
 	struct channel_t *ch;
 	struct un_t *un;
 	ulong lock_flags;
 	int rc = 0;
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return;
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return;
@@ -2466,11 +2466,11 @@ static int dgnc_tty_tiocmget(struct tty_
 	struct un_t *un;
 	int result = -EIO;
 	uchar mstat = 0;
 	ulong   lock_flags;
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return result;
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return result;
@@ -2525,11 +2525,11 @@ static int dgnc_tty_tiocmset(struct tty_
 	struct channel_t *ch;
 	struct un_t *un;
 	int ret = -EIO;
 	ulong   lock_flags;
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return ret;
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return ret;
@@ -2584,11 +2584,11 @@ static int dgnc_tty_send_break(struct tt
 	struct channel_t *ch;
 	struct un_t *un;
 	int ret = -EIO;
 	ulong   lock_flags;
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return ret;
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return ret;
@@ -2637,11 +2637,11 @@ static void dgnc_tty_wait_until_sent(str
 	struct board_t *bd;
 	struct channel_t *ch;
 	struct un_t *un;
 	int rc;
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return;
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return;
@@ -2673,11 +2673,11 @@ static void dgnc_tty_send_xchar(struct t
 	struct board_t *bd;
 	struct channel_t *ch;
 	struct un_t *un;
 	ulong   lock_flags;
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return;
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return;
@@ -2782,11 +2782,11 @@ static int dgnc_set_modem_info(struct tt
 	struct un_t *un;
 	int ret = -ENXIO;
 	unsigned int arg = 0;
 	ulong   lock_flags;
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return ret;
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return ret;
@@ -2880,11 +2880,11 @@ static int dgnc_tty_digigeta(struct tty_
 	ulong   lock_flags;
 
 	if (!retinfo)
 		return (-EFAULT);
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return (-EFAULT);
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return (-EFAULT);
@@ -2922,11 +2922,11 @@ static int dgnc_tty_digiseta(struct tty_
 	struct digi_t new_digi;
 	ulong lock_flags;
 
 	DPR_IOCTL(("DIGI_SETA start\n"));
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return (-EFAULT);
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return (-EFAULT);
@@ -3003,11 +3003,11 @@ static void dgnc_tty_set_termios(struct
 	struct board_t *bd;
 	struct channel_t *ch;
 	struct un_t *un;
 	unsigned long lock_flags;
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return;
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return;
@@ -3049,11 +3049,11 @@ static void dgnc_tty_throttle(struct tty
 {
 	struct channel_t *ch;
 	struct un_t *un;
 	ulong   lock_flags = 0;
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return;
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return;
@@ -3078,11 +3078,11 @@ static void dgnc_tty_unthrottle(struct t
 {
 	struct channel_t *ch;
 	struct un_t *un;
 	ulong   lock_flags;
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return;
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return;
@@ -3108,11 +3108,11 @@ static void dgnc_tty_start(struct tty_st
 	struct board_t *bd;
 	struct channel_t *ch;
 	struct un_t *un;
 	ulong lock_flags;
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return;
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return;
@@ -3142,11 +3142,11 @@ static void dgnc_tty_stop(struct tty_str
 	struct board_t *bd;
 	struct channel_t *ch;
 	struct un_t *un;
 	ulong lock_flags;
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return;
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return;
@@ -3189,11 +3189,11 @@ static void dgnc_tty_flush_chars(struct
 	struct board_t *bd;
 	struct channel_t *ch;
 	struct un_t *un;
 	ulong lock_flags;
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return;
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return;
@@ -3228,11 +3228,11 @@ static void dgnc_tty_flush_buffer(struct
 {
 	struct channel_t *ch;
 	struct un_t *un;
 	ulong lock_flags;
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return;
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return;
@@ -3298,11 +3298,11 @@ dgnc_tty_ioctl(struct tty_struct *tty, u
 	struct un_t *un;
 	int rc;
 	ulong lock_flags;
 	void __user *uarg = (void __user *) arg;
 
-	if (!tty || tty->magic != TTY_MAGIC)
+	if (!tty || !tty->ldisc)
 		return (-ENODEV);
 
 	un = tty->driver_data;
 	if (!un || un->magic != DGNC_UNIT_MAGIC)
 		return (-ENODEV);