linux-kernel - Re: [PATCH v2 5/6] X86: remove redundant cpuidle_idle

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Message-ID: <CAOesGMjvOkuxCopog91SAV1-gB9GaEYXpuXwhV1EJQor_pKjBA@mail.gmail.com>
Date:	Wed, 29 Jan 2014 11:02:28 -0800
From:	Olof Johansson <olof@...om.net>
To:	Nicolas Pitre <nicolas.pitre@...aro.org>
Cc:	Russell King <linux@....linux.org.uk>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	Paul Mundt <lethal@...ux-sh.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
	Linux-sh list <linux-sh@...r.kernel.org>,
	linux-pm@...r.kernel.org,
	"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>
Subject: Re: [PATCH v2 5/6] X86: remove redundant cpuidle_idle_call()

Hi,

On Wed, Jan 29, 2014 at 9:45 AM, Nicolas Pitre <nicolas.pitre@...aro.org> wrote:
> The core idle loop now takes care of it.
>
> Signed-off-by: Nicolas Pitre <nico@...aro.org>
> Acked-by: Daniel Lezcano <daniel.lezcano@...aro.org>
> ---
>  arch/x86/kernel/process.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
> index 3fb8d95ab8..4505e2a950 100644
> --- a/arch/x86/kernel/process.c
> +++ b/arch/x86/kernel/process.c
> @@ -298,10 +298,7 @@ void arch_cpu_idle_dead(void)
>   */
>  void arch_cpu_idle(void)
>  {
> -       if (cpuidle_idle_call())
> -               x86_idle();
> -       else
> -               local_irq_enable();
> +       x86_idle();

You're taking out the local_irq_enable() here but I don't see the
equivalent of adding it back in the 1/6 patch that moves the
cpuidle_idle_call() up to common code. It seems that one of the call
paths through cpuidle_idle_call() don't re-enable it on its own.

Even if this is the right thing to do, why it's OK to do so should
probably be documented in the patch description.


-Olof
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