linux-kernel - Re: [PATCH 04/12] ia64: Replace cpu_down with freeze_secondary

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Message-ID: <alpine.DEB.2.21.1911200944590.6731@nanos.tec.linutronix.de>
Date:   Wed, 20 Nov 2019 09:46:12 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Qais Yousef <qais.yousef@....com>
cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Tony Luck <tony.luck@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>, linux-ia64@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 04/12] ia64: Replace cpu_down with
 freeze_secondary_cpus

On Tue, 19 Nov 2019, Qais Yousef wrote:
> On 11/19/19 23:59, Thomas Gleixner wrote:
> > On Tue, 19 Nov 2019, Qais Yousef wrote:
> > > My plan was to simply make freeze_secondary_cpus() available and protected by
> > > CONFIG_SMP only instead.
> > > 
> > > Good plan?
> > 
> > No. freeze_secondary_cpus() is really for hibernation. Look at the exit
> > conditions there.
> 
> Hmm do you mean the pm_wakeup_pending() abort?
> 
> In arm64 we machine_shutdown() calls disable_nonboot_cpus(), which in turn
> a wrapper around freeze_secondary_cpus() with 0 passed as an argument.
> 
> IIUC this means arm64 could fail to offline all CPUs on machine_shutdown(),
> correct?

Looks like.

Thanks,

	tglx