linux-kernel - Re: [PATCH 3/4] USB: serial: add support for multi-interface functions

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Message-ID: <YGNCIT1ocatZ3V3/@hovoldconsulting.com>
Date:   Tue, 30 Mar 2021 17:22:09 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Oliver Neukum <oneukum@...e.com>
Cc:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] USB: serial: add support for multi-interface
 functions

On Tue, Mar 30, 2021 at 04:44:32PM +0200, Oliver Neukum wrote:
> Am Dienstag, den 30.03.2021, 16:38 +0200 schrieb Johan Hovold:
> > @@ -1115,6 +1161,8 @@ static void usb_serial_disconnect(struct usb_interface *interface)
> >         if (serial->type->disconnect)
> >                 serial->type->disconnect(serial);
> >  
> > +       release_sibling(serial, interface);
> > +
> >         /* let the last holder of this object cause it to be cleaned up */
> >         usb_serial_put(serial);
> >         dev_info(dev, "device disconnected\n");
> 
> Hi,
> 
> does this assume you are called for the original interface first?

No, I handle either interface being unbound first (e.g. see
release_sibling()).

> I am afraid that is an assumption you cannot make. In fact, if somebody
> is doing odd things with sysfs you cannot even assume both will see a
> disconnect()

Right, but disconnect() will still be called also for the sibling
interface as part of release_sibling() above.

Johan