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Message-ID: <20150501162915.GI27755@e104818-lin.cambridge.arm.com>
Date: Fri, 1 May 2015 17:29:15 +0100
From: Catalin Marinas <catalin.marinas@....com>
To: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc: will.deacon@....com, linux@....linux.org.uk,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
mingo@...nel.org
Subject: Re: [PATCH arm 1/2] arm64: Use common outgoing-CPU-notification code
On Fri, May 01, 2015 at 08:08:48AM -0700, Paul E. McKenney wrote:
> On Thu, Apr 30, 2015 at 10:50:55AM +0100, Catalin Marinas wrote:
> > On Thu, Apr 23, 2015 at 01:07:33PM -0700, Paul E. McKenney wrote:
> > > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> > > index 328b8ce4b007..6dc727a6e73e 100644
> > > --- a/arch/arm64/kernel/smp.c
> > > +++ b/arch/arm64/kernel/smp.c
> > > @@ -252,15 +252,13 @@ static int op_cpu_kill(unsigned int cpu)
> > > return cpu_ops[cpu]->cpu_kill(cpu);
> > > }
> > >
> > > -static DECLARE_COMPLETION(cpu_died);
> > > -
> > > /*
> > > * called on the thread which is asking for a CPU to be shutdown -
> > > * waits until shutdown has completed, or it is timed out.
> > > */
> > > void __cpu_die(unsigned int cpu)
> > > {
> > > - if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
> > > + if (!cpu_wait_death(cpu, 5)) {
> > > pr_crit("CPU%u: cpu didn't die\n", cpu);
> > > return;
> > > }
> > > @@ -293,7 +291,7 @@ void cpu_die(void)
> > > local_irq_disable();
> > >
> > > /* Tell __cpu_die() that this CPU is now safe to dispose of */
> > > - complete(&cpu_died);
> > > + (void)cpu_report_death();
> > >
> > > /*
> > > * Actually shutdown the CPU. This must never fail. The specific hotplug
> >
> > Are these functions are only defined when HOTPLUG_CPU is enabled? On
> > arm64 we can end up with this option disabled if SUSPEND is disabled.
>
> Yep, only with HOTPLUG_CPU. And yes, both SUSPEND and HIBERNATION can
> force HOTPLUG_CPU, so if you have neiter SUSPEND nor HIBERNATION, you
> won't have HOTPLUG_CPU. This -should- be OK, because you should also
> not have __cpu_die() if !HOTPLUG_CPU.
Ah, you are right. I got myself confused.
So is this patch ready for upstreaming or just for our information?
--
Catalin
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