TTY: remove unneeded tty->index checks

Checking if tty->index is in bounds is not needed. The tty has the
index set in the initial open. This is done in get_tty_driver. And it
can be only in interval <0,driver->num).

So remove the tests which check exactly this interval. Some are
left untouched as they check against the current backing device count.
(Leaving apart that the check is racy in most of the cases.)

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/crisv10.c

@@ -4105,20 +4105,11 @@ static int
 rs_open(struct tty_struct *tty, struct file * filp)
 {
 	struct e100_serial	*info;
-	int 			retval, line;
+	int 			retval;
 	unsigned long           page;
 	int                     allocated_resources = 0;
 
-	/* find which port we want to open */
-	line = tty->index;
-
-	if (line < 0 || line >= NR_PORTS)
-		return -ENODEV;
-
-	/* find the corresponding e100_serial struct in the table */
-	info = rs_table + line;
-
-	/* don't allow the opening of ports that are not enabled in the HW config */
+	info = rs_table + tty->index;
 	if (!info->enabled)
 		return -ENODEV;
 
@@ -4131,7 +4122,7 @@ rs_open(struct tty_struct *tty, struct file * filp)
 	tty->driver_data = info;
 	info->port.tty = tty;
 
-	info->port.tty->low_latency = (info->flags & ASYNC_LOW_LATENCY) ? 1 : 0;
+	tty->low_latency = !!(info->flags & ASYNC_LOW_LATENCY);
 
 	if (!tmp_buf) {
 		page = get_zeroed_page(GFP_KERNEL);