linux-kernel - Re: 3.2-rc2+: Reported regressions from 3.0 and 3.1

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Date:	Tue, 29 Nov 2011 19:34:28 +0100
From:	Borislav Petkov <bp@...64.org>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>, tglx@...utronix.de,
	mingo@...hat.com, hpa@...or.com, x86@...nel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux SCSI List <linux-scsi@...r.kernel.org>,
	Linux ACPI <linux-acpi@...r.kernel.org>,
	Network Development <netdev@...r.kernel.org>,
	Linux Wireless List <linux-wireless@...r.kernel.org>,
	DRI <dri-devel@...ts.freedesktop.org>,
	Florian Mickler <florian@...kler.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Kernel Testers List <kernel-testers@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux PM List <linux-pm@...ts.linux-foundation.org>,
	Maciej Rutecki <maciej.rutecki@...il.com>,
	deepthi@...ux.vnet.ibm.com
Subject: Re: 3.2-rc2+: Reported regressions from 3.0 and 3.1

On Tue, Nov 29, 2011 at 01:04:14PM -0500, Konrad Rzeszutek Wilk wrote:
> This patch:
> 
> commit d91ee5863b71e8c90eaf6035bff3078a85e2e7b5
> Author: Len Brown <len.brown@...el.com>
> Date:   Fri Apr 1 18:28:35 2011 -0400
> 
>     cpuidle: replace xen access to x86 pm_idle and default_idle
> 
>     ..scribble on pm_idle and access default_idle,
>    have it simply disable_cpuidle() so acpi_idle will not load and
>    architecture default HLT will be used.
> 
> idea was to have one call - disable_cpuidle() which would make
> pm_idle not be molested by other code. It disallows cpuidle_idle_call
> and acpi_idle_call to not set pm_idle (which is excellent). But the

what is acpi_idle_call, I can't find it anywhere.

> amd_e400_idle and mwait_idle can still setup pm_idle which we really
> do not want.

This is not the case: rather select_idle_routine()/idle_setup() sets
pm_idle.

[..]

> +bool set_pm_idle_to_default()
> +{
> +	if (!pm_idle) {
> +		pm_idle = default_idle;
> +		return true;
> +	}
> +	return false;
> +}

I don't understand what you're trying to achieve here? Do you want
default_idle to be always the pm_idle for xen or what is the deal here?

If yes, then simply do:

bool set_pm_idle_to_default(void)	// remember to add "void" for no function args
{
	bool ret = !!pm_idle;

	pm_idle = default_idle;

	return ret;

}

...

>  void stop_this_cpu(void *dummy)
>  {
>  	local_irq_disable();
> diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
> index 46d6d21..7506181 100644
> --- a/arch/x86/xen/setup.c
> +++ b/arch/x86/xen/setup.c
> @@ -448,6 +448,6 @@ void __init xen_arch_setup(void)
>  #endif
>  	disable_cpuidle();
>  	boot_option_idle_override = IDLE_HALT;
> -
> +	WARN_ON(!set_pm_idle_to_default());

and then do

	WARN_ON(set_pm_idle_to_default());

instead of having arbitrary confusing logic. This way you can warn
whether something else set pm_idle already. Or?

Thanks.

-- 
Regards/Gruss,
Boris.

Advanced Micro Devices GmbH
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