Re: [Xen-devel] Driver Architecture Changes

[Stefan Berger <stefanb@xxxxxxxxxx>]

Ewan Mellor <ewan@xxxxxxxxxxxxx> wrote on 11/17/2005
12:26:45 PM:

> On Wed, Nov 16, 2005 at 04:40:34PM -0500, Stefan Berger wrote:
> 
> > Hello Ewan,
> > 
> >   I am following the changes with the TPM driver pair. I
was wondering
> > what causes the 'add' action to be invoked on the hotplug scripts
and why
> > would one not see a remove action if a previous 'add' action
was
> > encountered and it had finished successfully.
> 
> The add action occurs when the device is registered with the kernel
> (xenbus_probe.c:xenbus_probe_node), and you should get a remove when
the
> device is no longer referenced.  Once the frontend driver has
flushed through
> and closed down, it switches to state Closed, which is seen in the
backend
> driver's otherend_changed function (blkback/xenbus.c:frontend_changed
for
> example).  This then calls device_unregister, which ought to
be enough to
> ensure that no-one is referencing the device, and so the kernel will
clean up
> the sysfs entries etc and you will get a remove hotplug event.

The mistake I had made was not to switch to the Closed
state. So now I am seeing the remove as well. Thanks.

Another question: I see that the .suspend function
is not used in the frontends anymore, but the structure still has that
member. Is the suspend member about to be removed?

> 
> If that's not happening, then there may be a bug which needs further
> investigation.

Was my bug.

  Stefan

> 
> HTH,
> 
> Ewan.
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