linux-kernel - Re: [PATCH] config: arm: exynos: remove PROVE

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Date:   Wed, 10 Oct 2018 12:09:44 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     l.luba@...tner.samsung.com
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Bartłomiej Żołnierkiewicz 
        <b.zolnierkie@...sung.com>, kgene@...nel.org,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [PATCH] config: arm: exynos: remove PROVE_LOCKING from defconfig

On Wed, 10 Oct 2018 at 11:56, Lukasz Luba <l.luba@...tner.samsung.com> wrote:
>
> Hi Krzysztof,
>
> Is it still valid that the Exynos has locking issues?

The prepare lock of clocks was not solved entirely. We just
implemented a set of workarounds.

> Or is it enabled 'just-in-case'?

Yes, all debugging features are implemented just in case to spot any
issue as early as possible.

> On arm64 the config misses that setting.
> Should be enabled there as well?

Because it is a shared defconfig among all platforms and apparently no
one wanted to convincing others to enable it.

> You have introduced this entry a year ago, probably during bug
> investigation.

Actually not, I enabled it much later after issues where discovered.

> The issue is in lockdep, the setting which enables it in Exynos
> is prove_locking. For now, just get rid of the second.
> My tests showed lockdep impact and not other minor debug features
> enabled.

You did not reply directly to my comment - you disabled all debug for
locking. It seems you are unaware of this so I question your test
results. If you run tests on this patch, then basically you compared
existing config with a config stripped out of debugging around locks.
I understand that this is not what you wanted...

Best regards,
Krzysztof