Re: [RFC v2 13/16] luo: add selftests for subsystems un/registration

[Mike Rapoport <rppt@kernel.org>]

On Thu, May 15, 2025 at 06:23:17PM +0000, Pasha Tatashin wrote:
> Introduce a self-test mechanism for the LUO to allow verification of
> core subsystem management functionality. This is primarily intended
> for developers and system integrators validating the live update
> feature.
> 
> The tests are enabled via the new Kconfig option
> CONFIG_LIVEUPDATE_SELFTESTS (default 'n') and are triggered through
> a new ioctl command, LIVEUPDATE_IOCTL_SELFTESTS, added to the
> /dev/liveupdate device node.
> 
> This ioctl accepts commands defined in luo_selftests.h to:
> - LUO_CMD_SUBSYSTEM_REGISTER: Creates and registers a dummy LUO
>   subsystem using the liveupdate_register_subsystem() function. It
>   allocates a data page and copies initial data from userspace.
> - LUO_CMD_SUBSYSTEM_UNREGISTER: Unregisters the specified dummy
>   subsystem using the liveupdate_unregister_subsystem() function and
>   cleans up associated test resources.
> - LUO_CMD_SUBSYSTEM_GETDATA: Copies the data page associated with a
>   registered test subsystem back to userspace, allowing verification of
>   data potentially modified or preserved by test callbacks.
> This provides a way to test the fundamental registration and
> unregistration flows within the LUO framework from userspace without
> requiring a full live update sequence.

I don't think ioctl for selftest is a good idea.
Can't we test register/unregister and state machine transitions with kunit?

And have a separate test module that registers as a subsystem, preserves
it's state and then verifies the state after the reboot. This will require
running qemu and qemu usage in tools/testing is a mess right now, but
still.

-- 
Sincerely yours,
Mike.