USB: serial: fix USB serial fix kfifo_len locking

This patch fix a possible race bug in drivers/usb/serial/generic with
the new kfifo API.

Please apply it to the 2.6.33-rc* tree.

Signed-off-by: Stefani Seibold <stefani@seibold.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 4 insertions, 4 deletions

diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index f1ea3a33b6e6..5ce033ab9b99 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -386,12 +386,12 @@ int usb_serial_generic_chars_in_buffer(struct tty_struct *tty)
 
         dbg("%s - port %d", __func__, port->number);
 
-        if (serial->type->max_in_flight_urbs) {
-                spin_lock_irqsave(&port->lock, flags);
+        spin_lock_irqsave(&port->lock, flags);
+        if (serial->type->max_in_flight_urbs)
                 chars = port->tx_bytes_flight;
-                spin_unlock_irqrestore(&port->lock, flags);
-        } else if (serial->num_bulk_out)
+        else if (serial->num_bulk_out)
                 chars = kfifo_len(&port->write_fifo);
+        spin_unlock_irqrestore(&port->lock, flags);
 
         dbg("%s - returns %d", __func__, chars);
         return chars;