Re: [PATCH v2] ARM: exynos_defconfig: Enable CONFIG_LOCKUP_DETECTOR

From: Krzysztof Kozlowski
Date: Wed Jan 07 2015 - 09:23:30 EST


On Åro, 2015-01-07 at 13:56 +0000, Anand Moon wrote:
> Hi Kszysztof Kozlowski,
>
> I picked up the bellow line from
>
>
> Documentation/locking/lockdep-design.txt line no 18
>
> I understand that by enabling this flag we could detect possible
>
> deadlock situation with the kernel. Sorry for the noise.

...and lockdep-design.txt describes LOCKDEP. Not LOCKUP. So why you are
enabling lockup?

Best regards,
Krzysztof

>
>
> -Anand Moon
>
>
>
> On Wednesday, January 7, 2015 6:57 PM, Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx> wrote:
> On Åro, 2015-01-07 at 18:29 +0530, Anand Moon wrote:
> > Enable CONFIG_LOCKUP_DETECTOR to validate kernel locks state for exynos SOC.
> >
> > Enabling CONFIG_LOCKUP_DETECTOR help validator tracks the 'state' of lock-classes,
> > and it tracks dependencies between different lock-classes.
> > The validator maintains a rolling proof that the state and
> > the dependencies are correct.
>
> Unfortunately this is not correct. Lockup detector does something else.
> Please read the help/manual for LOCKUP_DETECTOR. You can find in
> lib/Kconfig.debug (around line 667).
>
> Best regards,
> Krzysztof
>
> >
> > Changes since v2:
> > * Made commit message more clear
> > * Corrected grammer in code comment
> >
> > Tested on Exynos5422 ODROID XU3 board.
> >
> > Signed-off-by: Anand Moon <moon.linux@xxxxxxxxx>
> > Reviewed-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
> > ---
> > arch/arm/configs/exynos_defconfig | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/arm/configs/exynos_defconfig b/arch/arm/configs/exynos_defconfig
> > index 5ef14de..ecd9987 100644
> > --- a/arch/arm/configs/exynos_defconfig
> > +++ b/arch/arm/configs/exynos_defconfig
> > @@ -178,6 +178,7 @@ CONFIG_PRINTK_TIME=y
> > CONFIG_DEBUG_FS=y
> > CONFIG_MAGIC_SYSRQ=y
> > CONFIG_DEBUG_KERNEL=y
> > +CONFIG_LOCKUP_DETECTOR=y
> > CONFIG_DETECT_HUNG_TASK=y
> > CONFIG_DEBUG_RT_MUTEXES=y
> > CONFIG_DEBUG_SPINLOCK=y

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