ACPI / hotplug: Use device offline/online for graceful hot-removal
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() handling 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 'forced' device hot-removal, add a new sysfs attribute
'force_remove' that will reside under /sys/firmware/acpi/hotplug/.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index fe158fd..4fd3920 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -27,6 +27,12 @@
#define ACPI_IS_ROOT_DEVICE(device) (!(device)->parent)
+/*
+ * If set, devices will be hot-removed even if they cannot be put offline
+ * gracefully (from the kernel's standpoint).
+ */
+bool acpi_force_hot_remove;
+
static const char *dummy_hid = "device";
static LIST_HEAD(acpi_device_list);
@@ -120,6 +126,59 @@
}
static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);
+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;
+ 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) {
+ int ret;
+
+ ret = device_offline(pn->dev);
+ if (acpi_force_hot_remove)
+ 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)
{
acpi_handle handle = device->handle;
@@ -136,10 +195,33 @@
return -EINVAL;
}
+ lock_device_hotplug();
+
+ status = acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
+ NULL, acpi_bus_offline_companions, NULL,
+ NULL);
+ if (ACPI_SUCCESS(status) || acpi_force_hot_remove)
+ status = acpi_bus_offline_companions(handle, 0, NULL, NULL);
+
+ if (ACPI_FAILURE(status) && !acpi_force_hot_remove) {
+ 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_hotplug();
+
+ put_device(&device->dev);
+ return -EBUSY;
+ }
+
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"Hot-removing device %s...\n", dev_name(&device->dev)));
acpi_bus_trim(device);
+
+ unlock_device_hotplug();
+
/* Device node has been unregistered. */
put_device(&device->dev);
device = NULL;
@@ -236,6 +318,7 @@
int error;
mutex_lock(&acpi_scan_lock);
+ lock_device_hotplug();
acpi_bus_get_device(handle, &device);
if (device) {
@@ -259,6 +342,7 @@
kobject_uevent(&device->dev.kobj, KOBJ_ONLINE);
out:
+ unlock_device_hotplug();
acpi_evaluate_hotplug_ost(handle, ost_source, ost_code, NULL);
mutex_unlock(&acpi_scan_lock);
}