hvcs: Get reference to tty in remove

Grab a reference to the tty when removing the hvcs to ensure
it does not get freed unexpectedly.
Signed-off-by: NBrian King <brking@linux.vnet.ibm.com>
Link: https://lore.kernel.org/r/20230203155802.404324-4-brking@linux.vnet.ibm.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/hvc/hvcs.c

@@ -799,7 +799,7 @@ static void hvcs_remove(struct vio_dev *dev)
 
 	spin_lock_irqsave(&hvcsd->lock, flags);
 
-	tty = hvcsd->port.tty;
+	tty = tty_port_tty_get(&hvcsd->port);
 
 	spin_unlock_irqrestore(&hvcsd->lock, flags);
 
@@ -814,8 +814,10 @@ static void hvcs_remove(struct vio_dev *dev)
 	 * hvcs_hangup.  The tty should always be valid at this time unless a
 	 * simultaneous tty close already cleaned up the hvcs_struct.
 	 */
-	if (tty)
+	if (tty) {
 		tty_hangup(tty);
+		tty_kref_put(tty);
+	}
 
 	printk(KERN_INFO "HVCS: vty-server@%X removed from the"
 			" vio bus.\n", dev->unit_address);