On Wed, Jan 16, 2008 at 05:18:52PM +0100, Oliver Neukum wrote:
> Am Donnerstag, 20. Dezember 2007 16:51:59 schrieb Alan Stern:
> > On Thu, 20 Dec 2007, Oliver Neukum wrote:
> >
> > > @@ -1080,20 +1081,22 @@ void usb_serial_disconnect(struct usb_in
> > > usb_serial_console_disconnect(serial);
> > > dbg ("%s", __FUNCTION__);
> > >
> > > + mutex_lock(&serial->disc_mutex);
> > > usb_set_intfdata (interface, NULL);
> > > - if (serial) {
> > > - for (i = 0; i < serial->num_ports; ++i) {
> > > - port = serial->port[i];
> > > - if (port) {
> > > - if (port->tty)
> > > - tty_hangup(port->tty);
> > > - kill_traffic(port);
> > > - }
> > > + /* must use extra flag, as intfdata can be reset */
> > > + serial->disconnected = 1;
> >
> > This comment is misleading. It implies there is a possibility you
> > actually could check for disconnects by looking at the value of
> > usb_get_intfdata(), but that's completely wrong. There are about 13
> > places in various serial drivers where this mistake is made; they all
> > need to be fixed.
> >
> > Don't you also have to check the disconnect flag in serial_close()
> > before calling usb_autopm_put_interface()?
>
> Where is that?
>
> This fixes a problem where the mos7720 driver will make io to a device from
> which it has been logically disconnected. It does so by introducing a flag by
> which the generic usb serial code can signal the subdrivers their
> disconnection and appropriate locking.
>
> Signed-off-by: Oliver Neukum <[EMAIL PROTECTED]>
>
> I'd call this 2.6.25 material.
But does it really "solve" anything? Sure, it decreases the chance of a
race, but it can still happen (disconnect and close at the same time,
close starts to send messages before disconnect changes the
"disconnected" flag).
Or am I missing something else here?
thanks,
greg k-h
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