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

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Message-ID: <20191120104933.e6gkdjwkzulm6uak@e107158-lin.cambridge.arm.com>
Date:   Wed, 20 Nov 2019 10:49:34 +0000
From:   Qais Yousef <qais.yousef@....com>
To:     Thomas Gleixner <tglx@...utronix.de>
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 11/20/19 09:46, Thomas Gleixner wrote:
> 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.

Okay I'll double check and introduce a new function to be called from
machine_down() for arm64 and ia64 if necessary.

Thanks

--
Qais Yousef