On Mon, 2013-04-29 at 14:29 +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> Modify the generic ACPI hotplug code to be able to check if devices
> scheduled for hot-removal may be gracefully removed from the system
> using the device offline/online mechanism introduced previously.
>
> Namely, make acpi_scan_hot_remove() which handles device hot-removal
> call device_offline() for all physical companions of the ACPI device
> nodes involved in the operation and check the results. If any of
> the device_offline() calls fails, the function will not progress to
> the removal phase (which cannot be aborted), unless its (new) force
> argument is set (in case of a failing offline it will put the devices
> offlined by it back online).
>
> In support of the 'forced' hot-removal, add a new sysfs attribute
> 'force_remove' that will reside in every ACPI hotplug profile
> present under /sys/firmware/acpi/hotplug/.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
> Documentation/ABI/testing/sysfs-firmware-acpi | 9 +-
> drivers/acpi/internal.h | 2
> drivers/acpi/scan.c | 97 ++++++++++++++++++++++++--
> drivers/acpi/sysfs.c | 27 +++++++
> include/acpi/acpi_bus.h | 3
> 5 files changed, 131 insertions(+), 7 deletions(-)
>
:
> Index: linux-pm/drivers/acpi/scan.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/scan.c
> +++ linux-pm/drivers/acpi/scan.c
> @@ -120,7 +120,61 @@ acpi_device_modalias_show(struct device
> }
> static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);
>
> -static int acpi_scan_hot_remove(struct acpi_device *device)
> +static acpi_status acpi_bus_offline_companions(acpi_handle handle, u32 lvl,
> + void *data, void **ret_p)
> +{
> + struct acpi_device *device = NULL;
> + struct acpi_device_physical_node *pn;
> + bool force = *((bool *)data);
> + acpi_status status = AE_OK;
> +
> + if (acpi_bus_get_device(handle, &device))
> + return AE_OK;
> +
> + mutex_lock(&device->physical_node_lock);
> +
> + list_for_each_entry(pn, &device->physical_node_list, node) {
I do not think physical_node_list is set for ACPI processor devices, so
this code is NOP at this point. I think properly initializing
physical_node_list for CPU and memblk is one of the key items in this
approach.
> + int ret;
> +
> + ret = device_offline(pn->dev);
> + if (force)
> + continue;
> +
> + if (ret < 0) {
> + status = AE_ERROR;
> + break;
> + }
> + pn->put_online = !ret;
> + }
> +
> + mutex_unlock(&device->physical_node_lock);
> +
> + return status;
> +}
> +
> +static acpi_status acpi_bus_online_companions(acpi_handle handle, u32 lvl,
> + void *data, void **ret_p)
> +{
> + struct acpi_device *device = NULL;
> + struct acpi_device_physical_node *pn;
> +
> + if (acpi_bus_get_device(handle, &device))
> + return AE_OK;
> +
> + mutex_lock(&device->physical_node_lock);
> +
> + list_for_each_entry(pn, &device->physical_node_list, node)
> + if (pn->put_online) {
> + device_online(pn->dev);
> + pn->put_online = false;
> + }
> +
> + mutex_unlock(&device->physical_node_lock);
> +
> + return AE_OK;
> +}
> +
> +static int acpi_scan_hot_remove(struct acpi_device *device, bool force)
> {
> acpi_handle handle = device->handle;
> acpi_handle not_used;
> @@ -136,10 +190,30 @@ static int acpi_scan_hot_remove(struct a
> return -EINVAL;
> }
>
> + lock_device_offline();
> +
> + status = acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
> + NULL, acpi_bus_offline_companions, &force,
> + NULL);
> + if (ACPI_SUCCESS(status) || force)
> + status = acpi_bus_offline_companions(handle, 0, &force, NULL);
> +
> + if (ACPI_FAILURE(status) && !force) {
> + acpi_bus_online_companions(handle, 0, NULL, NULL);
> + acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
> + acpi_bus_online_companions, NULL, NULL,
> + NULL);
> + unlock_device_offline();
Don't we need put_device(&device->dev) here?
Thanks,
-Toshi
> + return -EBUSY;
> + }
> +
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