an open syscall now assignes file->private_data to a pointer to the
miscdevice structure. This reminds people not to duplicate code if
they want this and not to depend on it being NULL.
Signed-off-by: NMartin Kepplinger <martink@posteo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>