tty: fix chars_in_buffers

This function does not have an error return and returning an error is
instead interpreted as having a lot of pending bytes.

Reported by Jeff Harris who provided a list of some of the remaining
offenders.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/char/hvc_console.c

@@ -552,7 +552,7 @@ static int hvc_chars_in_buffer(struct tty_struct *tty)
 	struct hvc_struct *hp = tty->driver_data;
 
 	if (!hp)
-		return -1;
+		return 0;
 	return hp->n_outbuf;
 }
 

drivers/char/nozomi.c

@@ -1866,16 +1866,14 @@ static s32 ntty_chars_in_buffer(struct tty_struct *tty)
 {
 	struct port *port = tty->driver_data;
 	struct nozomi *dc = get_dc_by_tty(tty);
-	s32 rval;
+	s32 rval = 0;
 
 	if (unlikely(!dc || !port)) {
-		rval = -ENODEV;
 		goto exit_in_buffer;
 	}
 
 	if (unlikely(!port->port.count)) {
 		dev_err(&dc->pdev->dev, "No tty open?\n");
-		rval = -ENODEV;
 		goto exit_in_buffer;
 	}
 

drivers/char/pcmcia/ipwireless/tty.c

@@ -320,10 +320,10 @@ static int ipw_chars_in_buffer(struct tty_struct *linux_tty)
 	struct ipw_tty *tty = linux_tty->driver_data;
 
 	if (!tty)
-		return -ENODEV;
+		return 0;
 
 	if (!tty->open_count)
-		return -EINVAL;
+		return 0;
 
 	return tty->tx_bytes_queued;
 }

drivers/isdn/gigaset/interface.c

@@ -408,6 +408,8 @@ static int if_write_room(struct tty_struct *tty)
 	return retval;
 }
 
+/* FIXME: This function does not have error returns */
+
 static int if_chars_in_buffer(struct tty_struct *tty)
 {
 	struct cardstate *cs;

drivers/usb/class/cdc-acm.c

@@ -750,7 +750,7 @@ static int acm_tty_chars_in_buffer(struct tty_struct *tty)
 {
 	struct acm *acm = tty->driver_data;
 	if (!ACM_READY(acm))
-		return -EINVAL;
+		return 0;
 	/*
 	 * This is inaccurate (overcounts), but it works.
 	 */

drivers/usb/serial/mos7720.c

@@ -521,7 +521,7 @@ static int mos7720_chars_in_buffer(struct tty_struct *tty)
 	mos7720_port = usb_get_serial_port_data(port);
 	if (mos7720_port == NULL) {
 		dbg("%s:leaving ...........", __func__);
-		return -ENODEV;
+		return 0;
 	}
 
 	for (i = 0; i < NUM_URBS; ++i) {

drivers/usb/serial/ti_usb_3410_5052.c

@@ -727,7 +727,7 @@ static int ti_write_room(struct tty_struct *tty)
 	dbg("%s - port %d", __func__, port->number);
 
 	if (tport == NULL)
-		return -ENODEV;
+		return 0;
 
 	spin_lock_irqsave(&tport->tp_lock, flags);
 	room = ti_buf_space_avail(tport->tp_write_buf);
@@ -748,7 +748,7 @@ static int ti_chars_in_buffer(struct tty_struct *tty)
 	dbg("%s - port %d", __func__, port->number);
 
 	if (tport == NULL)
-		return -ENODEV;
+		return 0;
 
 	spin_lock_irqsave(&tport->tp_lock, flags);
 	chars = ti_buf_data_avail(tport->tp_write_buf);