From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Subject: Re: [PATCH] acpi : Add container online uevent to acpi_bus_attach
Date: Thu, 11 Sep 2014 01:38:37 +0200
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References: <54095EE7.3080302@jp.fujitsu.com> <6346979.uGFiy3j9K2@vostro.rjw.lan> <540FC29B.7010808@jp.fujitsu.com>
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To: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: rafael.j.wysocki@intel.com, mika.westerberg@linux.intel.com, linux-acpi@vger.kernel.org, jlee@suse.com

On Wednesday, September 10, 2014 12:16:43 PM Yasuaki Ishimatsu wrote:
> (2014/09/08 6:34), Rafael J. Wysocki wrote:
> > On Friday, September 05, 2014 03:57:43 PM Yasuaki Ishimatsu wrote:
> >> Container online uevent was deleted by "46394fd01 : ACPI / hotplug:
> >> Move container-specific code out of the core" because container-
> >> specific uevent is raised to udev by attaching container device.
> >> But the container-specific uevent is not useful.
> >>
> >> In my box, conainer device has CPU and memory devices. In this case,
> >> when hot adding container device, the following uevets are raised to
> >> udev.
> >>
> >>    # udevadm monitor --kernel
> >>    monitor will print the received events for:
> >>    KERNEL - the kernel uevent
> >>
> >>    KERNEL[...] add      /devices/system/container/ACPI0004:01 (container)
> >>    <snip>
> >>    KERNEL[...] add      /devices/system/memory/memory2048 (memory)
> >>    KERNEL[...] add      /devices/system/memory/memory2049 (memory)
> >>    <snip>
> >>    KERNEL[...] add      /devices/system/memory/memory2063 (memory)
> >>    <snip>
> >>    KERNEL[...] add      /devices/system/cpu/cpu60 (cpu)
> >>    <snip>
> >>    KERNEL[...] add      /devices/system/cpu/cpu119 (cpu)
> >>
> >> When udev catches the container add uevent in my box, udev executes
> >> user land script for onlining all child's devices. But memory and CPU
> >> devices have not been attached at this time. So user land script fails.
> >>
> >> One of solutions is that user land script waits for all child's devices
> >> to attach. But user land script has no way to know all child's devices
> >> were attached.
> >>
> >> So the patch adds container online uevent to acpi_bus_sttach(). By
> >> applying
> >> the patch, container online uevent is raised to udev after all child's
> >> devices were attached as follows:
> >>
> >>    # udevadm monitor --kernel
> >>    monitor will print the received events for:
> >>    KERNEL - the kernel uevent
> >>
> >>    KERNEL[...] add      /devices/system/container/ACPI0004:01 (container)
> >>    <snip>
> >>    KERNEL[...] add      /devices/system/memory/memory2048 (memory)
> >>    KERNEL[...] add      /devices/system/memory/memory2049 (memory)
> >>    <snip>
> >>    KERNEL[...] add      /devices/system/memory/memory2063 (memory)
> >>    <snip>
> >>    KERNEL[...] add      /devices/system/cpu/cpu60 (cpu)
> >>    <snip>
> >>    KERNEL[...] add      /devices/system/cpu/cpu119 (cpu)
> >>    KERNEL[...] online   /devices/system/container/ACPI0004:01 (container)
> >>
> >> So if user land script is executed after raising the container online
> >> uevent, it guarantees that all child's devices were attached.
> >
> > I see the problem, but I don't like the patch.
> >
> > For example, we don't need to match the container's name again, we can use
> > the fact that we've already matched the container scan handler to it.
> >
> > Does the one below work too?
> 
> Hi Rafael,
> 
> Thank you for posting your patch. I confirmed that your patch fixed my issue
> as folloes:
> 
> # udevadm monitor --kernel
> monitor will print the received events for:
> KERNEL - the kernel uevent
> 
> KERNEL[...] add      /devices/system/container/ACPI0004:01 (container)
> <snip>
> KERNEL[...] add      /devices/system/memory/memory2048 (memory)
> <snip>
> KERNEL[...] add      /devices/system/memory/memory2063 (memory)
> <snip>
> KERNEL[...] add      /devices/system/cpu/cpu60 (cpu)
> <snip>
> KERNEL[...] add      /devices/system/cpu/cpu119 (cpu)
> KERNEL[...] online   /devices/system/container/ACPI0004:01 (container)
> 
> So feel free to  add "Tested-by : Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>"
> to the patch.

Thanks!

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.