Re: [Qemu-devel] [PATCH 2/7] tests/qgraph: pci-pc driver and interface nodes

[Paolo Bonzini <pbonzini@redhat.com>]

On 11/07/2018 19:46, Emanuele wrote:
>>> +static void qpci(void)
>>> +{
>>> +    qos_node_create_interface("pci-bus");
>>> +}
>>> +
>>> +libqos_init(qpci);
>> Why does an interface need to be created?  The drivers declare which
>> interfaces they support?
>>
>> I don't think this can be used to detect typoes in the driver's
>> qos_node_produces() call since there is no explicit control over the
>> order in which libqos_init() functions are called.  So the driver may
>> call qos_node_produces() before the qos_node_create_interface() is
>> called?
> The interface is what is actually given to the test, so from there it
> can test the functions and fields regardless of which driver is actually
> implementing them.
> For example, sdhci-test uses the QSDHCI functions, and depending on the
> path the generic-sdhci or sdhci-pci functions will be used.

I think Stefan is right, if you adjust qos_node_create_interface so that
it is idempotent(*), you can make it static and call it from
qos_node_produces and qos_node_consumes.

(*) that is, fail like now if the node exists and is not an interface;
    but, succeed if the node exists and is an interface.

Thanks,

Paolo