If bailing out because there is nothing to receive in rp_do_receive(),
tty_ldisc_deref is not called.  Failure to do so increases the ref count=20
and causes release_dev() to hang since it can't get the ref count to 0.
Signed-off-by: Michal Ostrowski <mostrows@watson.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>