fault injection: query if a fault has been injected?

fault injection: query if a fault has been injected?

[Jani Nikula]

Hi Akinobu -

The i915 driver has its own fault injection mechanism that we're in the
process of migrating to the kernel generic fault injection.

One feature we have is being able to check if a fault has been injected
in the driver. We could then tone down certain error/warning messages to
debug messages. The point being, CI could more trivially ignore the
expected failures, while still failing on errors and warnings that are
unrelated to the injected fault.

Is there anything like that in the generic fault injection mechanism? Or
do we have to figure all of this out in user space?


BR,
Jani.

-- 
Jani Nikula, Intel

Re: fault injection: query if a fault has been injected?

[Akinobu Mita]

2025年11月27日(木) 21:49 Jani Nikula <jani.nikula@intel.com>:
>
>
> Hi Akinobu -
>
> The i915 driver has its own fault injection mechanism that we're in the
> process of migrating to the kernel generic fault injection.
>
> One feature we have is being able to check if a fault has been injected
> in the driver. We could then tone down certain error/warning messages to
> debug messages. The point being, CI could more trivially ignore the
> expected failures, while still failing on errors and warnings that are
> unrelated to the injected fault.
>
> Is there anything like that in the generic fault injection mechanism? Or
> do we have to figure all of this out in user space?

I took a quick look at the i915 driver's fault injection.

The fail-nth function may be useful for implementing inject_probe_failure.
The section "Systematic faults using fail-nth" in
Documentation/fault-injection/fault-injection.rst explains this.