[PATCH i-g-t 0/3] lib/kunit: Support writable filter* parameters of kunit module

[Janusz Krzysztofik]

On Friday, 26 January 2024 15:46:54 CET Lucas De Marchi wrote:
> On Thu, Jan 25, 2024 at 11:25:55AM -0600, Lucas De Marchi wrote:
> >On Thu, Jan 25, 2024 at 05:52:09PM +0100, Janusz Krzysztofik wrote:
> >>Instead of wasting resources on reloading the base Kunit module each time
> >>a different set of filter parameters is needed, try to write the required
> >>values to sysfs representation of those parameters.  If that fails (e.g.
> >>on older LTS kernels with read-only filter parameters), fall back to
> >
> >we can't really execute anything on LTS kernel. I don't think think it's
> >worth keeping the multiple fallbacks we have now.
> >q
> >I think trying to maintain compat is good, but I'm not sure it makes
> >sense for these tightly coupled tests with the kernel.
> 
> I gave it a try and it doesn't really work for me. It seems that after
> you list the tests, the filter_action remains on skip, so the tests just
> skips.
> 
> $ sudo ./build/tests/xe_live_ktest --r dmabuf
> ...
> Subtest dmabuf: SKIP (0.078s)
> $ sudo grep . /sys/module/kunit/parameters/*
> /sys/module/kunit/parameters/action:(null)
> /sys/module/kunit/parameters/filter:module=none
> /sys/module/kunit/parameters/filter_action:skip
> /sys/module/kunit/parameters/filter_glob:*
> /sys/module/kunit/parameters/stats_enabled:1
> 
> This works for me (with my additional patch to rename the module):
> 
> # # list tests
> # modprobe xe_live_test
> # echo -n 'skip' > /sys/module/kunit/parameters/filter_action
> # echo -n '*' > /sys/module/kunit/parameters/filter_glob
> # modprobe xe_live_test
> 
> # # run just xe_dma_buf
> # modprobe -r xe_live_test
> # echo -ne '0x00' > /sys/module/kunit/parameters/filter_action
> # echo -n 'xe_dma_buf' > /sys/module/kunit/parameters/filter_glob
> # modprobe xe_live_test
> 
> I  think the main issue is that kunit have some different code paths for
> not param == NULL and also that writting an empty string is not really
> working as it doesn't issue a write() syscall. If you force a \0 and use
> len + 1, then I think it might work, but I didn't test it completely.
> I may have to enhance the patch on the kernel side to handle that more
> effectively.

OK, if you are going to enhance the kernel side then I'll hold on for now and 
get back to it when we can call the ABI stable.

Thanks,
Janusz

> 
> Lucas De Marchi
>