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 <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
mrwenhui · Jan 20, 2010 · 25719e6 · 25719e6
1 parent 24bc734
commit 25719e6
Showing 1 changed file with 4 additions and 4 deletions.
diff --git 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;