Subject: Re: [PATCH] powerpc/smp: Do not disable IPI interrupts during suspend

From: Zhao Chenhui <[email-masked]>
Date: Thu, 2 Aug 2012 18:04:18 +0800

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 <[email-masked]>
> > > Signed-off-by: Li Yang <[email-masked]>
> > > ---
> > > 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