linux-kernel - Re: [PATCH] acpi: check the online state of all children in container

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Message-ID: <20170322030118.GD20835@linux-l9pv.suse>
Date:   Wed, 22 Mar 2017 11:01:18 +0800
From:   joeyli <jlee@...e.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     "Lee, Chun-Yi" <joeyli.kernel@...il.com>,
        Len Brown <lenb@...nel.org>, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, Michal Hocko <mhocko@...e.com>,
        Jiri Kosina <jkosina@...e.cz>
Subject: Re: [PATCH] acpi: check the online state of all children in container

On Wed, Mar 22, 2017 at 01:58:30AM +0100, Rafael J. Wysocki wrote:
> On Wednesday, March 22, 2017 09:01:48 AM Lee, Chun-Yi wrote:
> > Just checking the state of container is not enough to confirm that
> > the whole container is offlined.
> 
> And why is that so?
>

Actually there does not have real kernel issue triggered by this code now.
I reviewed code and found the difference between acpi_container_offline().

Considering a container that it includes devices and sub-containers
like this:

Scope (_SB)
    Device (MODU)
	Name (_HID, "ACPI0004")		<===  main-container
        Device (PCIE)
		Name (_HID, EisaId ("PNP0A08"))
        Device (SUBM)
            	Name (_HID, "ACPI0004")		<=== sub-container
		Device (MEM0)
			Name (_HID, EisaId ("PNP0C80"))
	...

The original code checks the physical nodes on the main container but
doesn't check children's physical nodes. So, it may happen the sub-container
didn't offline but the offline checking of main container is pass. 

Please kindly direct me if I misunderstood or missed any detail in the codes
about physcial node and container offline.

Thank a lot!
Joey Lee