linux-kernel - Re: [PATCH v5 2/4] acpi_processor: do not mark present at boot but not onlined CPU as onlined

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Message-ID: <20140508111730.GA5074@gmail.com>
Date:	Thu, 8 May 2014 13:17:30 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Igor Mammedov <imammedo@...hat.com>, linux-kernel@...r.kernel.org,
	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	x86@...nel.org, bp@...e.de, paul.gortmaker@...driver.com,
	JBeulich@...e.com, prarit@...hat.com, drjones@...hat.com,
	toshi.kani@...com, riel@...hat.com, gong.chen@...ux.intel.com,
	andi@...stfloor.org, lenb@...nel.org, linux-acpi@...r.kernel.org
Subject: Re: [PATCH v5 2/4] acpi_processor: do not mark present at boot but
 not onlined CPU as onlined


* Rafael J. Wysocki <rjw@...ysocki.net> wrote:

> On Thursday, May 08, 2014 08:09:35 AM Ingo Molnar wrote:
> > 
> > * Rafael J. Wysocki <rjw@...ysocki.net> wrote:
> > 
> > > On Monday, May 05, 2014 10:49:49 PM Igor Mammedov wrote:
> > > > acpi_processor_add() assumes that present at boot CPUs
> > > > are always onlined, it is not so if a CPU failed to become
> > > > onlined. As result acpi_processor_add() will mark such CPU
> > > > device as onlined in sysfs and following attempts to
> > > > online/offline it using /sys/device/system/cpu/cpuX/online
> > > > attribute will fail.
> > > > 
> > > > Do not poke into device internals in acpi_processor_add()
> > > > and touch "struct device { .offline }" attribute, since
> > > > for CPUs onlined at boot it's set by:
> > > >   topology_init() -> arch_register_cpu() -> register_cpu()
> > > > before ACPI device tree is parsed, and for hotplugged
> > > > CPUs it's set when userspace onlines CPU via sysfs.
> > > > 
> > > > Signed-off-by: Igor Mammedov <imammedo@...hat.com>
> > > > Acked-by: Toshi Kani <toshi.kani@...com>
> > > 
> > > Would there be a problem if I applied this separately from the rest 
> > > of the series?
> > 
> > If you push the fix upstream for v3.15 then it would be fine and I 
> > could base the other patches on top of your (soon to be upstream) 
> > commit.
> 
> OK, I can do that.
> 
> We also seem to need this in -stable, right?

Yeah, agreed.

Thanks,

	Ingo
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