Here is a new version of the patch to usb-serial.c to fix
the unbalanced kref and module get/put in serial_open and
serial_close when there are errors.  This version works
correctly when try_module_get fails and now "rmmod --wait"
works correctly.


* If the low level usb serial open fails, the kref and
  module use counts are decremented once in open.  Before,
  they were mistakenly decremented again in close.

* If try_module_get fails, the module use count is not
  changed.  Before, the module use count was mistakenly
  decremented.  Now "rmmod --wait" works correctly.

* The tty->driver_data pointer is never set to NULL once
  the port is open.  Before there was a small window when
  it was mistakenly set to NULL for an already open port.
Signed-off-by: Al Borchers <alborchers@steinerpoint.com>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>