Re: [12/14] torture: Add testing of RCU's Rust bindings to torture.sh

[Joel Fernandes <joelagnelf@nvidia.com>]

Hi Paul,

On 4/18/2025 6:45 PM, Paul E. McKenney wrote:
>>>>> Suppose we fired up a guest OS and captured the console output.  Is there
>>>>> a way to make that guest OS shut down automatically at the end of the
>>>>> test and to extract the test results?
>>>> Ah, sorry, I thought you were already doing something like that, i.e.
>>>> that perhaps you could reuse some kernel build you already had and
>>>> avoiding a full rebuild/mrproper. The KUnit Python script uses QEMU
>>>> and parses the results; e.g. you could look for the results lines
>>>> like:
>>>>
>>>>     # Totals: pass:133 fail:0 skip:0 total:133
>>>>     ok 2 rust_doctests_kernel
>>>>
>>> Alternatively, I could clone a copy of the current archive into a
>>> temporary directory, "make mrproper" there, run kunit normally, then
>>> clean up the temporary directory.  Extra storage, but quite a bit
>>> more robust and user-friendly.
>>>
>> Just to be on the same page, is the concern about the
>> slowness of mrproper or that it kills the kernel build
>> artifacts requiring a clean build?
>
> It blows away things like tags and cscope databases.  Me, I have my
> cscope databases elsewhere, but lots of people build them for their
> live git repos.  And they are (quite understandably) unhappy when their
> source-code browsing tools are blown away by some random test doing an
> unsuspected "make mrproper".  😉

Cool. One thing is, running other test modes in torture.sh also reconfigures the
kernel and potentially recompiles the entire kernel as a result. So if someone
is already having their own kernel build, running torture.sh already may cause
them to have to do a full rebuild, AFAICS. But yes, and to your point, the
cscope DB and stuff may get blown away for additional disruption.

> 
>> What kind of improvement are we looking for and why would
>> this patch in its current form not work?
> For the near term, I am OK with its current form because it is
> non-default.  Longer term, though, we need it to be tested by default,
> and that means making it avoid undoing people's work.  My short-term
> approach is to enable this test on my employer's test systems, which
> have Rust set up correctly, and skip it on my laptop, which has a strange
> FrankenRust due to my early playing around with that language.
> 
Or we teach kunit.py to not require a mrproper? :-) I wonder why it needs to do
that. I may run into that too considering my other kernel project requires me to
mess around with rust.

thanks,

 - Joel