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

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Message-ID: <1404184557.18325.32.camel@ale.ozlabs.ibm.com>
Date:	Mon, 30 Jun 2014 22:15:57 -0500
From:	Michael Neuling <mikey@...ling.org>
To:	Michael Ellerman <mpe@...erman.id.au>
Cc:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	benh@...nel.crashing.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 Tue, 2014-07-01 at 10:52 +1000, Michael Ellerman wrote:
> 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 ;)

It's always nice to know that in battle a comrade will throw himself on
a grenade to save you. :-P

Actually, I'm pretty sure this happened when you were away (probably on
a beach somewhere), I was forward porting the patch set, hit a conflict
and fucked it up.  

Mikey

> 
> 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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