Re: question on tty open and close

[Marcel Holtmann <marcel@holtmann.org>]

Hi Alan,

> > As long as the new behavior continues to call
> > driver->close() if driver->open() succeeds
> > then I see no problem.
> 
> It breaks if any existing driver is doing no cleanup in ->open() when it
> fails but relying upon ->close() being called. That is what needs
> auditing first of all.

I know at least that the Bluetooth TTY emulation (RFCOMM) will break
since I have a big fat warning in my code:

        /* We don't leak this refcount. For reasons which are not entirely
           clear, the TTY layer will call our ->close() method even if the
           open fails. We decrease the refcount there, and decreasing it
           here too would cause breakage. */
        dev = rfcomm_dev_get(id);
        if (!dev)
                return -ENODEV;

Regards

Marcel