ACPI: Add ACPI CPU hot-remove support

Added support of CPU hot-remove via an ACPI eject notification.
It calls acpi_bus_hot_remove_device(), which shares the same code
path with the sysfs eject operation.  acpi_os_hotplug_execute()
runs the hot-remove operation in kacpi_hotplug_wq and serializes
it between ACPI hot-remove and sysfs eject requests.
Signed-off-by: NToshi Kani <toshi.kani@hp.com>
Reviewed-by: NYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Tested-by: NIgorMammedov <imammedo@redhat.com>
Tested-by: NVijay Mohan Pandarathil <vijaymohan.pandarathil@hp.com>
Tested-by: NPrarit Bhargava <prarit@redhat.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/processor_driver.c

@@ -695,8 +695,8 @@ int acpi_processor_device_add(acpi_handle handle, struct acpi_device **device)
 static void acpi_processor_hotplug_notify(acpi_handle handle,
 					  u32 event, void *data)
 {
-	struct acpi_processor *pr;
 	struct acpi_device *device = NULL;
+	struct acpi_eject_event *ej_event = NULL;
 	u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
 	int result;
 
@@ -728,20 +728,27 @@ static void acpi_processor_hotplug_notify(acpi_handle handle,
 				  "received ACPI_NOTIFY_EJECT_REQUEST\n"));
 
 		if (acpi_bus_get_device(handle, &device)) {
-			printk(KERN_ERR PREFIX
-				    "Device don't exist, dropping EJECT\n");
+			pr_err(PREFIX "Device don't exist, dropping EJECT\n");
 			break;
 		}
-		pr = acpi_driver_data(device);
-		if (!pr) {
-			printk(KERN_ERR PREFIX
-				    "Driver data is NULL, dropping EJECT\n");
+		if (!acpi_driver_data(device)) {
+			pr_err(PREFIX "Driver data is NULL, dropping EJECT\n");
 			break;
 		}
 
-		/* REVISIT: update when eject is supported */
-		ost_code = ACPI_OST_SC_EJECT_NOT_SUPPORTED;
-		break;
+		ej_event = kmalloc(sizeof(*ej_event), GFP_KERNEL);
+		if (!ej_event) {
+			pr_err(PREFIX "No memory, dropping EJECT\n");
+			break;
+		}
+
+		ej_event->handle = handle;
+		ej_event->event = ACPI_NOTIFY_EJECT_REQUEST;
+		acpi_os_hotplug_execute(acpi_bus_hot_remove_device,
+					(void *)ej_event);
+
+		/* eject is performed asynchronously */
+		return;
 
 	default:
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,