linux-kernel - Re: [Xen-devel] Re: [PATCH 1/3] cpuidle: If disable_cpuidle() is called, set pm_idle to default

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Message-ID: <20111122134612.GA29668@phenom.dumpdata.com>
Date:	Tue, 22 Nov 2011 08:46:12 -0500
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	Deepthi Dharwar <deepthi@...ux.vnet.ibm.com>
Cc:	len.brown@...el.com, jeremy@...p.org,
	xen-devel@...ts.xensource.com, x86@...nel.org,
	linux-kernel@...r.kernel.org, trenn@...e.de, mingo@...hat.com,
	bp@...en8.de, hpa@...or.com, tj@...nel.org, tglx@...utronix.de,
	stable@...nel.org
Subject: Re: [Xen-devel] Re: [PATCH 1/3] cpuidle: If disable_cpuidle() is
 called, set pm_idle to default_idle.

On Tue, Nov 15, 2011 at 09:40:04AM -0500, Konrad Rzeszutek Wilk wrote:
> > Well I was with a view that if cpuidle is disabled, mwait and arm_e400
> > would take precedence over default_idle. But if is ok to have default_idle instead,
> > then go ahead. 
> > 
> > > Perhaps there is another way do this is:
> > > 
> > > diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
> > > index becd6d9..04b10a4 100644
> > > --- a/drivers/cpuidle/cpuidle.c
> > > +++ b/drivers/cpuidle/cpuidle.c
> > > @@ -38,6 +38,7 @@ int cpuidle_disabled(void)
> > >  void disable_cpuidle(void)
> > >  {
> > >  	off = 1;
> > > +	pm_idle = default_idle;
> > >  }
> > > 
> > Brining pm_idle pointer back to cpuidle code is going a step back coz
> > we wanted to complete remove using pm_idle going forward. As having 
> > a pointer exported into various files is not a good thing. That's the 
> > reason we started the clean up in the first place :) 
> 
> Perhaps then something along these lines, where we still set default_idle
> but don't fiddle with the pm_idle (and can still rip out the
> EXPORT_SYMBOL_GPL(default_idle) in 2012):
> 
> (Hadn't tested this yet).

Now have tested it.

> 
> diff --git a/arch/x86/include/asm/system.h b/arch/x86/include/asm/system.h
> index c2ff2a1..2d2f01c 100644
> --- a/arch/x86/include/asm/system.h
> +++ b/arch/x86/include/asm/system.h
> @@ -401,6 +401,7 @@ extern unsigned long arch_align_stack(unsigned long sp);
>  extern void free_init_pages(char *what, unsigned long begin, unsigned long end);
>  
>  void default_idle(void);
> +bool set_pm_idle_to_default(void);
>  
>  void stop_this_cpu(void *dummy);
>  
> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
> index e7e3b01..bfb113f 100644
> --- a/arch/x86/kernel/process.c
> +++ b/arch/x86/kernel/process.c
> @@ -403,6 +403,14 @@ void default_idle(void)
>  EXPORT_SYMBOL(default_idle);
>  #endif
>  
> +bool set_pm_idle_to_default()
> +{
> +	if (!pm_idle) {
> +		pm_idle = default_idle;
> +		return true;
> +	}
> +	return false;
> +}
>  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());
>  	fiddle_vdso();
>  }
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@...ts.xensource.com
> http://lists.xensource.com/xen-devel
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