USB: pl2303: clean up line-status handling

Clean up line-status handling somewhat.
Get tty-reference only when actually needed.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 15 insertions, 11 deletions

diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index 9951dfddc784..11de1f169308 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -808,7 +808,8 @@ static void pl2303_update_line_status(struct usb_serial_port *port,
         struct tty_struct *tty;
         unsigned long flags;
         unsigned int status_idx = UART_STATE_INDEX;
-        u8 prev_line_status;
+        u8 status;
+        u8 delta;
 
         if (spriv->quirks & PL2303_QUIRK_UART_STATE_IDX0)
                 status_idx = 0;
@@ -816,24 +817,27 @@ static void pl2303_update_line_status(struct usb_serial_port *port,
         if (actual_length < status_idx + 1)
                 return;
 
+        status = data[status_idx];
+
         /* Save off the uart status for others to look at */
         spin_lock_irqsave(&priv->lock, flags);
-        prev_line_status = priv->line_status;
-        priv->line_status = data[status_idx];
+        delta = priv->line_status ^ status;
+        priv->line_status = status;
         spin_unlock_irqrestore(&priv->lock, flags);
 
-        if (priv->line_status & UART_BREAK_ERROR)
+        if (status & UART_BREAK_ERROR)
                 usb_serial_handle_break(port);
 
         wake_up_interruptible(&port->port.delta_msr_wait);
 
-        tty = tty_port_tty_get(&port->port);
-        if (!tty)
-                return;
-        if ((priv->line_status ^ prev_line_status) & UART_DCD)
-                usb_serial_handle_dcd_change(port, tty,
-                                priv->line_status & UART_DCD);
-        tty_kref_put(tty);
+        if (delta & UART_DCD) {
+                tty = tty_port_tty_get(&port->port);
+                if (tty) {
+                        usb_serial_handle_dcd_change(port, tty,
+                                                        status & UART_DCD);
+                        tty_kref_put(tty);
+                }
+        }
 }
 
 static void pl2303_read_int_callback(struct urb *urb)