linux-kernel - Re: [PATCH] powerpc/powernv: Check for IRQHAPPENED before sleeping

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Date:	Tue, 01 Jul 2014 10:52:06 +1000
From:	Michael Ellerman <mpe@...erman.id.au>
To:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>
Cc:	benh@...nel.crashing.org, mikey@...ling.org,
	shreyas@...ux.vnet.ibm.com, svaidy@...ux.vnet.ibm.com,
	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powerpc/powernv: Check for IRQHAPPENED before sleeping

On Mon, 2014-06-30 at 11:54 +0530, Preeti U Murthy wrote:
> Commit 8d6f7c5a: "powerpc/powernv: Make it possible to skip the IRQHAPPENED
> check in power7_nap()" added code that prevents even cores which enter sleep
> on idle, from checking for pending interrupts. Fix this.

To be clear, it is a bug in the original commit. Mikey and I pair programmed
that code, and he was *definitely* typing at that point ;)

Can you please include in the changelog what the symptom of the bug is, and
have you seen it in practice?

The bad commit went into 3.16-rc1, so we don't need to backport this to any
stable release.

cheers

> diff --git a/arch/powerpc/kernel/idle_power7.S b/arch/powerpc/kernel/idle_power7.S
> index 2480256..5cf3d36 100644
> --- a/arch/powerpc/kernel/idle_power7.S
> +++ b/arch/powerpc/kernel/idle_power7.S
> @@ -131,7 +131,7 @@ _GLOBAL(power7_nap)
>  
>  _GLOBAL(power7_sleep)
>  	li	r3,1
> -	li	r4,0
> +	li	r4,1
>  	b	power7_powersave_common
>  	/* No return */
>  
> 





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