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Date: Thu, 26 Dec 2013 12:10:04 +0900
From: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>
CC: ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
LKML <linux-kernel@...r.kernel.org>,
Toshi Kani <toshi.kani@...com>,
Yinghai Lu <yinghai@...nel.org>,
Zhang Rui <rui.zhang@...el.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Mika Westerberg <mika.westerberg@...ux.intel.com>,
Aaron Lu <aaron.lu@...el.com>
Subject: Re: [PATCH 1/2][Untested] ACPI / hotplug: Add demand_offline hotplug
profile flag
(2013/12/23 23:00), Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>
> Add a new ACPI hotplug profile flag, demand_offline, such that if
> set for the given ACPI device object's scan handler, it will cause
> acpi_scan_hot_remove() to check if that device object's physical
> companions are offline upfront and fail the hot removal if that
> is not the case.
>
> That flag will be useful to overcome a problem with containers on
> some system where they can only be hot-removed after some cleanup
> operations carried out by user space, which needs to be notified
> of the container hot-removal before the kernel attempts to offline
> devices in the container. In those cases the current implementation
> of acpi_scan_hot_remove() is not sufficient, because it first tries
> to offline the devices in the container and only if that is
> suffcessful it tries to offline the container itself. As a result,
> the container hot-removal notification is not delivered to user space
> at the right time.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
> drivers/acpi/scan.c | 41 +++++++++++++++++++++++++++++++++++++----
> include/acpi/acpi_bus.h | 3 ++-
> 2 files changed, 39 insertions(+), 5 deletions(-)
>
> Index: linux-pm/drivers/acpi/scan.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/scan.c
> +++ linux-pm/drivers/acpi/scan.c
> @@ -126,6 +126,24 @@ acpi_device_modalias_show(struct device
> }
> static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);
>
> +static bool acpi_scan_is_offline(struct acpi_device *adev)
> +{
> + struct acpi_device_physical_node *pn;
> + bool offline = true;
> +
> + mutex_lock(&adev->physical_node_lock);
> +
> + list_for_each_entry(pn, &adev->physical_node_list, node)
> + if (!pn->dev->offline) {
Please check pn->dev->bus and pn->dev->bus->offline too as follow:
if (pn->dev->bus && pn->dev->bus->offline &&
!pn->dev->offline) {
My container has CPU and Memory and PCI root bridge. PCI root bridge
does not has offline function (pn->dev->bus->offline). So I cannot offline
the device and pn->dev->offline of the device is always 0. Therefore,
following operation always returns -EBUSY even if I offline CPUs and
all memory sections on a container device.
echo 0 > /sys/bus/container/devices/ACPI0004:01/online
Thanks,
Yasuaki Ishimatsu
> + kobject_uevent(&pn->dev->kobj, KOBJ_CHANGE);
> + offline = false;
> + break;
> + }
> +
> + mutex_unlock(&adev->physical_node_lock);
> + return offline;
> +}
> +
> static acpi_status acpi_bus_offline(acpi_handle handle, u32 lvl, void *data,
> void **ret_p)
> {
> @@ -196,12 +214,11 @@ static acpi_status acpi_bus_online(acpi_
> return AE_OK;
> }
>
> -static int acpi_scan_hot_remove(struct acpi_device *device)
> +static int acpi_scan_try_to_offline(struct acpi_device *device)
> {
> acpi_handle handle = device->handle;
> - struct device *errdev;
> + struct device *errdev = NULL;
> acpi_status status;
> - unsigned long long sta;
>
> /*
> * Carry out two passes here and ignore errors in the first pass,
> @@ -212,7 +229,6 @@ static int acpi_scan_hot_remove(struct a
> *
> * If the first pass is successful, the second one isn't needed, though.
> */
> - errdev = NULL;
> status = acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
> NULL, acpi_bus_offline, (void *)false,
> (void **)&errdev);
> @@ -241,6 +257,23 @@ static int acpi_scan_hot_remove(struct a
> return -EBUSY;
> }
> }
> + return 0;
> +}
> +
> +static int acpi_scan_hot_remove(struct acpi_device *device)
> +{
> + acpi_handle handle = device->handle;
> + unsigned long long sta;
> + acpi_status status;
> +
> + if (device->handler->hotplug.demand_offline && !acpi_force_hot_remove) {
> + if (!acpi_scan_is_offline(device))
> + return -EBUSY;
> + } else {
> + int error = acpi_scan_try_to_offline(device);
> + if (error)
> + return error;
> + }
>
> ACPI_DEBUG_PRINT((ACPI_DB_INFO,
> "Hot-removing device %s...\n", dev_name(&device->dev)));
> Index: linux-pm/include/acpi/acpi_bus.h
> ===================================================================
> --- linux-pm.orig/include/acpi/acpi_bus.h
> +++ linux-pm/include/acpi/acpi_bus.h
> @@ -91,8 +91,9 @@ struct acpi_device;
>
> struct acpi_hotplug_profile {
> struct kobject kobj;
> - bool enabled:1;
> int (*scan_dependent)(struct acpi_device *adev);
> + bool enabled:1;
> + bool demand_offline:1;
> };
>
> static inline struct acpi_hotplug_profile *to_acpi_hotplug_profile(
>
--
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