linux-kernel - Re: [PATCH] powerpc/smp: Do not disable IPI interrupts during suspend

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Message-ID: <20120802100418.GA13777@localhost.localdomain>
Date:	Thu, 2 Aug 2012 18:04:18 +0800
From:	Zhao Chenhui <chenhui.zhao@...escale.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC:	Kumar Gala <galak@...nel.crashing.org>,
	"linuxppc-dev@...ts.ozlabs.org list" <linuxppc-dev@...ts.ozlabs.org>,
	"linux-kernel@...r.kernel.org list" <linux-kernel@...r.kernel.org>,
	Li Yang <leoli@...escale.com>
Subject: Re: [PATCH] powerpc/smp: Do not disable IPI interrupts during suspend

On Sat, Jul 28, 2012 at 08:20:31AM +1000, Benjamin Herrenschmidt wrote:
> On Fri, 2012-07-27 at 16:58 -0500, Kumar Gala wrote:
> > On Jul 20, 2012, at 7:47 AM, Zhao Chenhui wrote:
> > 
> > > During suspend, all interrupts including IPI will be disabled. In this case,
> > > the suspend process will hang in SMP. To prevent this, pass the flag
> > > IRQF_NO_SUSPEND when requesting IPI irq.
> > > 
> > > Signed-off-by: Zhao Chenhui <chenhui.zhao@...escale.com>
> > > Signed-off-by: Li Yang <leoli@...escale.com>
> > > ---
> > > arch/powerpc/kernel/smp.c |    2 +-
> > > 1 files changed, 1 insertions(+), 1 deletions(-)
> > 
> > BenH,
> > 
> > Can you ack?
> 
> No I'll merge it but not until it's been in next for a bit unless you
> have some strong emergency there, it's on my mental list of things to
> shovel into next after rc1.
> 
> Curiosity: didn't we use to disable all non-boot CPUs on suspend ?
> 
> Cheers,
> Ben.

Yes, we disabled all non-boot CPUs on suspend by calling disable_nonboot_cpus().
The disable_nonboot_cpus() needs IPIs to work. But prior to
calling disable_nonboot_cpus(), the IPIs are disabled in dpm_suspend_noirq().

-Chenhui

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