linux-kernel - Re: [PATCH 0/2] clk: kunit: Fix the lockdep warnings

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Date:   Wed, 9 Aug 2023 17:02:01 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Stephen Boyd <sboyd@...nel.org>,
        Maxime Ripard <mripard@...nel.org>,
        Michael Turquette <mturquette@...libre.com>
Cc:     linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel test robot <yujie.liu@...el.com>,
        kunit-dev@...glegroups.com
Subject: Re: [PATCH 0/2] clk: kunit: Fix the lockdep warnings

On 8/9/23 16:21, Stephen Boyd wrote:
> +kunit-dev
> 
> Quoting Maxime Ripard (2023-07-21 00:09:31)
>> Hi,
>>
>> Here's a small series to address the lockdep warning we have when
>> running the clk kunit tests with lockdep enabled.
>>
>> For the record, it can be tested with:
>>
>> $ ./tools/testing/kunit/kunit.py run \
>>      --kunitconfig=drivers/clk \
>>      --cross_compile aarch64-linux-gnu- --arch arm64 \
>>      --kconfig_add CONFIG_DEBUG_KERNEL=y \
>>      --kconfig_add CONFIG_PROVE_LOCKING=y
>>
>> Let me know what you think,
> 
> Thanks for doing this. I want to roll these helpers into the clk_kunit.c
> file that I had created for some other clk tests[1]. That's mostly
> because clk.c is already super long and adding kunit code there makes
> that problem worse. I'll try to take that patch out of the rest of the
> series and then add this series on top and resend.
> 
> I don't know what to do about the case where CONFIG_KUNIT=m though. We
> have to export clk_prepare_lock/unlock()? I really don't want to do that
> even if kunit is enabled (see EXPORT_SYMBOL_IF_KUNIT). Maybe if there
> was a GPL version of that, so proprietary modules can't get at kernel
> internals on kunit enabled kernels.
> 

EXPORT_SYMBOL_IF_KUNIT defines a module namespace. You could go a step
further and define a CLK_KUNIT module namespace or similar. That would
of course still permit abuse, but it would have to be _very_ intentional.
There is an EXPORT_SYMBOL_NS_GPL(), so you could further restrict it
to GPL only.

Guenter