USB: more serial drivers writing after disconnect

this covers the rest of the obvious cases by using the flags
and locks to guard against disconnect which were introduced
in the earlier patch against mos7720.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>


diff --git a/drivers/usb/serial/visor.c b/drivers/usb/serial/visor.c
index c234799..22b3f78 100644
--- a/drivers/usb/serial/visor.c
+++ b/drivers/usb/serial/visor.c
@@ -362,7 +362,7 @@
 			kfree (transfer_buffer);
 		}
 	}
-	mutex_lock(&port->serial->disc_mutex);
+	mutex_unlock(&port->serial->disc_mutex);
 
 	if (stats)
 		dev_info(&port->dev, "Bytes In = %d  Bytes Out = %d\n",