Merge tag 'mfd-3.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/sameo/mfd-2.6

[cascardo/linux.git] / drivers / usb / serial / usb-serial.c

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 64bda13..a19ed74 100644 (file)
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -361,15 +361,21 @@ static int serial_write_room(struct tty_struct *tty)
 static int serial_chars_in_buffer(struct tty_struct *tty)
 {
        struct usb_serial_port *port = tty->driver_data;
+       struct usb_serial *serial = port->serial;
+       int count = 0;
 
        dev_dbg(tty->dev, "%s - port %d\n", __func__, port->number);
 
+       mutex_lock(&serial->disc_mutex);
        /* if the device was unplugged then any remaining characters
           fell out of the connector ;) */
-       if (port->serial->disconnected)
-               return 0;
-       /* pass on to the driver specific version of this function */
-       return port->serial->type->chars_in_buffer(tty);
+       if (serial->disconnected)
+               count = 0;
+       else
+               count = serial->type->chars_in_buffer(tty);
+       mutex_unlock(&serial->disc_mutex);
+
+       return count;
 }
 
 static void serial_throttle(struct tty_struct *tty)
@@ -688,10 +694,20 @@ static int serial_carrier_raised(struct tty_port *port)
 static void serial_dtr_rts(struct tty_port *port, int on)
 {
        struct usb_serial_port *p = container_of(port, struct usb_serial_port, port);
-       struct usb_serial_driver *drv = p->serial->type;
+       struct usb_serial *serial = p->serial;
+       struct usb_serial_driver *drv = serial->type;
 
-       if (drv->dtr_rts)
+       if (!drv->dtr_rts)
+               return;
+       /*
+        * Work-around bug in the tty-layer which can result in dtr_rts
+        * being called after a disconnect (and tty_unregister_device
+        * has returned). Remove once bug has been squashed.
+        */
+       mutex_lock(&serial->disc_mutex);
+       if (!serial->disconnected)
                drv->dtr_rts(p, on);
+       mutex_unlock(&serial->disc_mutex);
 }
 
 static const struct tty_port_operations serial_port_ops = {