From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Igor Mammedov <imammedo@redhat.com>
Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com,
        hpa@zytor.com, x86@kernel.org, bp@suse.de,
        paul.gortmaker@windriver.com, JBeulich@suse.com, prarit@redhat.com,
        drjones@redhat.com, toshi.kani@hp.com, riel@redhat.com,
        gong.chen@linux.intel.com, andi@firstfloor.org, lenb@kernel.org,
        linux-acpi@vger.kernel.org
Subject: Re: [PATCH v3 5/5] acpi_processor: do not mark present at boot but not onlined CPU as onlined
Date: Tue, 15 Apr 2014 07:43 +0200
Message-ID: <3026804.eniy6FZ71k@vostro.rjw.lan>
User-Agent: KMail/4.11.5 (Linux/3.14.0-rc7+; KDE/4.11.5; x86_64; ; )
In-Reply-To: <1397150061-29735-6-git-send-email-imammedo@redhat.com>
References: <1397150061-29735-1-git-send-email-imammedo@redhat.com> <1397150061-29735-6-git-send-email-imammedo@redhat.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 7Bit
Content-Type: text/plain; charset="utf-8"
Sender: linux-kernel-owner@vger.kernel.org

On Thursday, April 10, 2014 07:14:21 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.

What do you mean by that?  What *exactly* is the failure scenario?

> 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@redhat.com>
> ---
>  drivers/acpi/acpi_processor.c |    3 ---
>  1 files changed, 0 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> index c29c2c3..d56e4b4 100644
> --- a/drivers/acpi/acpi_processor.c
> +++ b/drivers/acpi/acpi_processor.c
> @@ -403,9 +403,6 @@ static int acpi_processor_add(struct acpi_device *device,
>  	if (result)
>  		goto err;
>  
> -	pr->dev = dev;

The line above has to stay as is.

> -	dev->offline = pr->flags.need_hotplug_init;
> -
>  	/* Trigger the processor driver's .probe() if present. */
>  	if (device_attach(dev) >= 0)
>  		return 1;
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/