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References: <20220518073232.526443-1-davidgow@google.com> <20220518073232.526443-2-davidgow@google.com>
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From:   Daniel Latypov <dlatypov@google.com>
Date:   Wed, 18 May 2022 10:12:33 -0700
Message-ID: <CAGS_qxoVucD5N00g3Tjav5gmYQWvxndTWJYHuKY6mH4bkWXGgA@mail.gmail.com>
Subject: Re: [PATCH 2/2] kcsan: test: Add a .kunitconfig to run KCSAN tests
To:     David Gow <davidgow@google.com>
Cc:     Brendan Higgins <brendanhiggins@google.com>,
        Marco Elver <elver@google.com>,
        Shuah Khan <skhan@linuxfoundation.org>,
        Dmitry Vyukov <dvyukov@google.com>, kunit-dev@googlegroups.com,
        kasan-dev@googlegroups.com, linux-kselftest@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Wed, May 18, 2022 at 12:32 AM David Gow <davidgow@google.com> wrote:
> 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

Just noting here, if we go with --qemu_args [1], then we'd change this to
  --arch=x86_64 --qemu_args='-smp 8'
and then probably add
  CONFIG_SMP=y
to this file.

[1] https://lore.kernel.org/linux-kselftest/20220518170124.2849497-1-dlatypov@google.com

> +
> +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
> +
> +# 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

Tangent:

Ah this reminds me, unfortunately you can't use --kconfig_add to
overwrite this atm.
Right now, it'll just blindly try to append and then complain that one
of the two copies of the option is missing.

That might be a feature to look into.
Or at least, we can maybe give a better error message.

E.g. with the default kunitconfig, the error currently looks like
# Try to overwrite CONFIG_KUNIT_ALL_TESTS=y
$ ./tools/testing/kunit/kunit.py config --kconfig_add=CONFIG_KUNIT_ALL_TESTS=m
...
ERROR:root:Not all Kconfig options selected in kunitconfig were in the
generated .config.
This is probably due to unsatisfied dependencies.
Missing: CONFIG_KUNIT_ALL_TESTS=m