[RFC] How to test panic handlers, without crashing the kernel

[Jocelyn Falempe]

On 05/03/2024 18:50, Guilherme G. Piccoli wrote:
> On 05/03/2024 13:52, Jocelyn Falempe wrote:
>> [...]
>> Or maybe have two lists of panic notifiers, the safe and the destructive
>> list. So in case of fake panic, we can only call the safe notifiers.
>>
> 
> I tried something like that:
> https://lore.kernel.org/lkml/20220427224924.592546-1-gpiccoli@igalia.com/
> 
> There were many suggestions, a completely refactor of the idea (panic
> lists are not really seen as reliable things).

Thanks for sharing this, so it's much more complex than what I though.
> 
> Given that, I'm not really sure splitting in lists gonna fly; maybe
> restricting the test infrastructure to drm_panic plus some paths of
> panic would be enough for this debugfs interface, in principle? I mean,
> to unblock your work on the drm panic stuff.

For drm_panic, I changed the way the debugfs is calling the drm_panic 
functions in the last version:
https://patchwork.freedesktop.org/patch/581845/?series=122244&rev=9

It doesn't use the panic notifier list, but create a file for each plane 
of each device directly.
It allows to test the panic handler, not in a real panic condition, but 
that's still better than nothing.

> 
> Cheers,
> 
> 
> Guilherme
> 

Best regards,

-- 

Jocelyn