linux-kernel - Re: [PATCH] Remove unnecessary irq disabling

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Message-ID: <4637D459.2040502@rtr.ca>
Date:	Tue, 01 May 2007 19:59:21 -0400
From:	Mark Lord <lkml@....ca>
To:	Glauber de Oliveira Costa <gcosta@...hat.com>
Cc:	ak@...e.de, akpm@...ux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Remove unnecessary irq disabling

Glauber de Oliveira Costa wrote:
> RR asks us if it is really necessary to disable interrupts in
> setup_secondary_APIC_clock(). The answer is no, since setup_APIC_timer()
> starts by saving irq flags, which also disables them.
> 
> Signed-off-by: Glauber de Oliveira Costa <gcosta@...hat.com>
> 
> --- a/arch/x86_64/kernel/apic.c
> +++ b/arch/x86_64/kernel/apic.c
> @@ -875,9 +875,7 @@ void __init setup_boot_APIC_clock (void)
>  
>  void __cpuinit setup_secondary_APIC_clock(void)
>  {
> -	local_irq_disable(); /* FIXME: Do we need this? --RR */
>  	setup_APIC_timer(calibration_result);
> -	local_irq_enable();
>  }
>  
>  void disable_APIC_timer(void)

Okay, I'll bite:  before the patch, this code would exit
with interrupts *enabled*, always.   Now it does not.

What does that break, or was it already broken and this fixes it?

Cheers
-
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