USB: serial: digi_acceleport: add chars_in_buffer locking

Both the dp_write_urb_in_use flag and dp_out_buf_len counter should be
accessed while holding the driver port lock. Add the missing locking to
chars_in_buffer and clean up the implementation somewhat by using a
common exit path.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

diff --git a/drivers/usb/serial/digi_acceleport.c b/drivers/usb/serial/digi_acceleport.c
index a4194b70a6fea026a0e174cb900a9fd6ce02d408..754c66ff0fc11b04e0f2ec2299c50fa92854144b 100644 (file)
--- a/drivers/usb/serial/digi_acceleport.c
+++ b/drivers/usb/serial/digi_acceleport.c
@@ -1044,17 +1044,19 @@ static unsigned int digi_chars_in_buffer(struct tty_struct *tty)
 {
        struct usb_serial_port *port = tty->driver_data;
        struct digi_port *priv = usb_get_serial_port_data(port);
+       unsigned long flags;
+       unsigned int chars;
 
-       if (priv->dp_write_urb_in_use) {
-               dev_dbg(&port->dev, "digi_chars_in_buffer: port=%d, chars=%d\n",
-                       priv->dp_port_num, port->bulk_out_size - 2);
-               return port->bulk_out_size - 2;
-       } else {
-               dev_dbg(&port->dev, "digi_chars_in_buffer: port=%d, chars=%d\n",
-                       priv->dp_port_num, priv->dp_out_buf_len);
-               return priv->dp_out_buf_len;
-       }
+       spin_lock_irqsave(&priv->dp_port_lock, flags);
+       if (priv->dp_write_urb_in_use)
+               chars = port->bulk_out_size - 2;
+       else
+               chars = priv->dp_out_buf_len;
+       spin_unlock_irqrestore(&priv->dp_port_lock, flags);
 
+       dev_dbg(&port->dev, "%s: port=%d, chars=%d\n", __func__,
+                       priv->dp_port_num, chars);
+       return chars;
 }
 
 static void digi_dtr_rts(struct usb_serial_port *port, int on)