Am Donnerstag, 29. Mai 2003 18:22 schrieb Alan Stern:
> On Thu, 29 May 2003, Oliver Neukum wrote:
> > > > Device reset is a partial re-enmeration. I suspect some
> > > > of the issues there would go better if it were more of
> > > > a full re-enumeration (you said something similar). And
> > > > again, that's normally done in some other thread (say,
> > > > scsi-eh).
> > >
> > > It overlaps the first of your tasks above: everything up to the ADDRESS
> > > state. There's no need to pick a configuration; we simply re-use the
> > > one previously in effect. The interfaces, sysfs stuff, drivers, and so
> > > on
> >
> > If we can. We need to deal with errors here.
>
> Do we? Maybe that should be left to the driver that requested the reset.
> Clearly we don't really want to have incorrect records, such as a device
> stuck in config 0 when we think it's in config 1. But this is presumably
> a temporary situation and at some point the driver will ask the core to
> reload the configuration descriptors.
To a certain extend we need to deal with it. It's core's business if it
happens with adr 0 state. And we need to deal with it if the driver gives up.
Which means that the core gets the hard irrecoverable errors ;-)
And we need a means for the drivers to tell the core about such cases.
[..]
> > For this very reason usb_device_reset() exists in a very without locking.
> > So that it can be done in probe(). I tried a lot of games with
> > rw-semaphores but in the end that doesn't pay off. We might go for a lock
> > with ownership but that doesn't sound attractive either.
>
> I imagine much of this processing will be done with dev->serialize held.
> That should take care of everything but the address-0 part, for which
> there is a separate semaphore.
That's the way it was before conversion to the driver model.
I think I myself introduced a lock against subsys.rwsem, but I no
longer remember the reason.
Regards
Oliver
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