Re: [PATCH 2/2] kcsan: test: Add a .kunitconfig to run KCSAN tests

[Marco Elver <elver@google.com>]

On Wed, May 18, 2022 at 03:32PM +0800, David Gow wrote:
> Add a .kunitconfig file, which provides a default, working config for
> running the KCSAN tests. Note that it needs to run on an SMP machine, so
> to run under kunit_tool, the x86_64-smp qemu-based setup should be used:
> ./tools/testing/kunit/kunit.py run --arch=x86_64-smp --kunitconfig=kernel/kcsan
> 
> Signed-off-by: David Gow <davidgow@google.com>

Reviewed-by: Marco Elver <elver@google.com>

Thanks for adding this.

> ---
>  kernel/kcsan/.kunitconfig | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
>  create mode 100644 kernel/kcsan/.kunitconfig
> 
> diff --git a/kernel/kcsan/.kunitconfig b/kernel/kcsan/.kunitconfig
> new file mode 100644
> index 000000000000..a8a815b1eb73
> --- /dev/null
> +++ b/kernel/kcsan/.kunitconfig
> @@ -0,0 +1,20 @@
> +# Note that the KCSAN tests need to run on an SMP setup.
> +# Under kunit_tool, this can be done by using the x86_64-smp
> +# qemu-based architecture:
> +# ./tools/testing/kunit/kunit.py run --kunitconfig=kernel/kcsan --arch=x86_64-smp
> +
> +CONFIG_KUNIT=y
> +
> +CONFIG_DEBUG_KERNEL=y
> +
> +CONFIG_KCSAN=y
> +CONFIG_KCSAN_KUNIT_TEST=y
> +
> +# Needed for test_barrier_nothreads
> +CONFIG_KCSAN_STRICT=y
> +CONFIG_KCSAN_WEAK_MEMORY=y

Note, KCSAN_STRICT implies KCSAN_WEAK_MEMORY.

Also, a bunch of the test cases' outcomes depend on KCSAN's
"strictness". I think to cover the various combinations would be too
complex, but we can just settle on testing KCSAN_STRICT=y.

The end result is the same, but you could drop the
CONFIG_KCSAN_WEAK_MEMORY=y line, and let the latest KCSAN_STRICT
defaults decide (I don't expect them to change any time soon).

If you want it to be more explicit, it's also fine leaving the
CONFIG_KCSAN_WEAK_MEMORY=y line in.

> +# This prevents the test from timing out on many setups. Feel free to remove
> +# (or alter) this, in conjunction with setting a different test timeout with,
> +# for example, the --timeout kunit_tool option.
> +CONFIG_KCSAN_REPORT_ONCE_IN_MS=100
> -- 
> 2.36.0.550.gb090851708-goog
>