Re: [linux-usb-devel] Re: [PATCH] USB changes for 2.5.58

Oliver Neukum
2003-01-21T00:50:55Z

Am Dienstag, 21. Januar 2003 01:44 schrieb David Brownell:
> Oliver Neukum wrote:
> >>So you were talking past what I said about notifying that highest level,
> >>not disagreeing with it.
> >
> > I was trying to make the point that callbacks have no place in that
> > process.
>
> If so, you didn't persuade me ...
>
> > It must go bottom to top and that's it.
>
> ... because those disconnect() callbacks are exactly how USB and PCI
> deliver that notification to the "top" level, and you've already agreed
> that SCSI needs to accomodate those models. So clearly they have at least
> that much of a place.

Disconnect is not really a callback. There's a distinct lack of a back movement here.
khubd -> usbcore -> disconnect() in driver -> [layer on top]

The proposed API in SCSI looks like:
<bus system> -> LLD -> midlayer -> top layer -> midlayer -> LLD with destroy_slave()
and that's not OK.

> > Refusing to take notice of a device removal is just not an option.
> > This is exactly what the current SCSI idea of an API to do bus removal
> > does.
>
> I perceive violent agreement that a change is needed in that area.
>
> But the next step there would seem to be a patch to the SCSI APIs,
> unless I mis-understood what Matt was saying about the issue he ran
> into when making usb-storage use the enumeration facilities in the
> current SCSI mid/low layers.

I have some horrible notions when I see what APIs grace the SCSI layer.

Regards
Oliver