Re: [RFC/PATCH v0 01/12] hw/arm/virt: Avoid NULL pointer de-reference

[Markus Armbruster]

Philippe Mathieu-Daudé <philmd@linaro.org> writes:

> Hi Srivatsa,
>
> (+Markus/Peter for QOM fu)

QOM fu needs Paolo; cc'ed.

I'm not sure how much this is about QOM, though.  Perhaps it's more
about good taste.

> On 11/10/23 18:52, Srivatsa Vaddagiri wrote:
>> Avoid dereferencing a NULL pointer that its_class_name() could return.
>
> While your patch is correct, there is some code smell
> around its_class_name(). IMHO a foo_class_name() handler
> should never return NULL.
>
> I'm trying to rework apic_get_class() similarly, see:
> https://lore.kernel.org/qemu-devel/20231003082728.83496-1-philmd@linaro.org/

In both cases, we have a function to find the device model to use with
current QEMU configuration and system state.  The fact that one of them
returns a class name and the other a class is detail.

Observe: this usable device model exists for any QEMU configuration.  It
may not be usable in certain system states, though.

Since the function deals with both, it can fail.

We can separate the two concerns: first map configuration to device
model (can't fail), then check the system state (can fail).

Feels like a matter of taste to me.  Does it result in simpler function
contracts and more readable code?  Can we do it the same way everywhere?