Merge tag 'acpi-6.3-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull ACPI fix from Rafael Wysocki:
 "Fix a recent regression related to the handling of ACPI notifications
  that made it more likely for ACPI driver callbacks to be invoked in an
  unexpected order and NULL pointers can be dereferenced as a result or
  similar.

  The fix is to modify the global ACPI notification handler so it does
  not invoke driver callbacks at all and allow the device-level
  notification handlers to receive "system" notifications (for the
  drivers that want to receive them)"

* tag 'acpi-6.3-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI: bus: Rework system-level device notification handling

Author: torvalds

drivers/acpi/bus.c

@@ -459,85 +459,67 @@ static void acpi_bus_osc_negotiate_usb_control(void)
                              Notification Handling
    -------------------------------------------------------------------------- */
 
-/*
- * acpi_bus_notify
- * ---------------
- * Callback for all 'system-level' device notifications (values 0x00-0x7F).
+/**
+ * acpi_bus_notify - Global system-level (0x00-0x7F) notifications handler
+ * @handle: Target ACPI object.
+ * @type: Notification type.
+ * @data: Ignored.
+ *
+ * This only handles notifications related to device hotplug.
  */
 static void acpi_bus_notify(acpi_handle handle, u32 type, void *data)
 {
 	struct acpi_device *adev;
-	u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE;
-	bool hotplug_event = false;
 
 	switch (type) {
 	case ACPI_NOTIFY_BUS_CHECK:
 		acpi_handle_debug(handle, "ACPI_NOTIFY_BUS_CHECK event\n");
-		hotplug_event = true;
 		break;
 
 	case ACPI_NOTIFY_DEVICE_CHECK:
 		acpi_handle_debug(handle, "ACPI_NOTIFY_DEVICE_CHECK event\n");
-		hotplug_event = true;
 		break;
 
 	case ACPI_NOTIFY_DEVICE_WAKE:
 		acpi_handle_debug(handle, "ACPI_NOTIFY_DEVICE_WAKE event\n");
-		break;
+		return;
 
 	case ACPI_NOTIFY_EJECT_REQUEST:
 		acpi_handle_debug(handle, "ACPI_NOTIFY_EJECT_REQUEST event\n");
-		hotplug_event = true;
 		break;
 
 	case ACPI_NOTIFY_DEVICE_CHECK_LIGHT:
 		acpi_handle_debug(handle, "ACPI_NOTIFY_DEVICE_CHECK_LIGHT event\n");
 		/* TBD: Exactly what does 'light' mean? */
-		break;
+		return;
 
 	case ACPI_NOTIFY_FREQUENCY_MISMATCH:
 		acpi_handle_err(handle, "Device cannot be configured due "
 				"to a frequency mismatch\n");
-		break;
+		return;
 
 	case ACPI_NOTIFY_BUS_MODE_MISMATCH:
 		acpi_handle_err(handle, "Device cannot be configured due "
 				"to a bus mode mismatch\n");
-		break;
+		return;
 
 	case ACPI_NOTIFY_POWER_FAULT:
 		acpi_handle_err(handle, "Device has suffered a power fault\n");
-		break;
+		return;
 
 	default:
 		acpi_handle_debug(handle, "Unknown event type 0x%x\n", type);
-		break;
+		return;
 	}
 
 	adev = acpi_get_acpi_dev(handle);
-	if (!adev)
-		goto err;
-
-	if (adev->dev.driver) {
-		struct acpi_driver *driver = to_acpi_driver(adev->dev.driver);
-
-		if (driver && driver->ops.notify &&
-		    (driver->flags & ACPI_DRIVER_ALL_NOTIFY_EVENTS))
-			driver->ops.notify(adev, type);
-	}
-
-	if (!hotplug_event) {
-		acpi_put_acpi_dev(adev);
-		return;
-	}
 
-	if (ACPI_SUCCESS(acpi_hotplug_schedule(adev, type)))
+	if (adev && ACPI_SUCCESS(acpi_hotplug_schedule(adev, type)))
 		return;
 
 	acpi_put_acpi_dev(adev);
 
- err:
-	acpi_evaluate_ost(handle, type, ost_code, NULL);
+	acpi_evaluate_ost(handle, type, ACPI_OST_SC_NON_SPECIFIC_FAILURE, NULL);
 }
 
 static void acpi_notify_device(acpi_handle handle, u32 event, void *data)
@@ -562,42 +544,51 @@ static u32 acpi_device_fixed_event(void *data)
 	return ACPI_INTERRUPT_HANDLED;
 }
 
-static int acpi_device_install_notify_handler(struct acpi_device *device)
+static int acpi_device_install_notify_handler(struct acpi_device *device,
+					      struct acpi_driver *acpi_drv)
 {
 	acpi_status status;
 
-	if (device->device_type == ACPI_BUS_TYPE_POWER_BUTTON)
+	if (device->device_type == ACPI_BUS_TYPE_POWER_BUTTON) {
 		status =
 		    acpi_install_fixed_event_handler(ACPI_EVENT_POWER_BUTTON,
 						     acpi_device_fixed_event,
 						     device);
-	else if (device->device_type == ACPI_BUS_TYPE_SLEEP_BUTTON)
+	} else if (device->device_type == ACPI_BUS_TYPE_SLEEP_BUTTON) {
 		status =
 		    acpi_install_fixed_event_handler(ACPI_EVENT_SLEEP_BUTTON,
 						     acpi_device_fixed_event,
 						     device);
-	else
-		status = acpi_install_notify_handler(device->handle,
-						     ACPI_DEVICE_NOTIFY,
+	} else {
+		u32 type = acpi_drv->flags & ACPI_DRIVER_ALL_NOTIFY_EVENTS ?
+				ACPI_ALL_NOTIFY : ACPI_DEVICE_NOTIFY;
+
+		status = acpi_install_notify_handler(device->handle, type,
 						     acpi_notify_device,
 						     device);
+	}
 
 	if (ACPI_FAILURE(status))
 		return -EINVAL;
 	return 0;
 }
 
-static void acpi_device_remove_notify_handler(struct acpi_device *device)
+static void acpi_device_remove_notify_handler(struct acpi_device *device,
+					      struct acpi_driver *acpi_drv)
 {
-	if (device->device_type == ACPI_BUS_TYPE_POWER_BUTTON)
+	if (device->device_type == ACPI_BUS_TYPE_POWER_BUTTON) {
 		acpi_remove_fixed_event_handler(ACPI_EVENT_POWER_BUTTON,
 						acpi_device_fixed_event);
-	else if (device->device_type == ACPI_BUS_TYPE_SLEEP_BUTTON)
+	} else if (device->device_type == ACPI_BUS_TYPE_SLEEP_BUTTON) {
 		acpi_remove_fixed_event_handler(ACPI_EVENT_SLEEP_BUTTON,
 						acpi_device_fixed_event);
-	else
-		acpi_remove_notify_handler(device->handle, ACPI_DEVICE_NOTIFY,
+	} else {
+		u32 type = acpi_drv->flags & ACPI_DRIVER_ALL_NOTIFY_EVENTS ?
+				ACPI_ALL_NOTIFY : ACPI_DEVICE_NOTIFY;
+
+		acpi_remove_notify_handler(device->handle, type,
 					   acpi_notify_device);
+	}
 }
 
 /* Handle events targeting \_SB device (at present only graceful shutdown) */
@@ -1039,7 +1030,7 @@ static int acpi_device_probe(struct device *dev)
 		 acpi_drv->name, acpi_dev->pnp.bus_id);
 
 	if (acpi_drv->ops.notify) {
-		ret = acpi_device_install_notify_handler(acpi_dev);
+		ret = acpi_device_install_notify_handler(acpi_dev, acpi_drv);
 		if (ret) {
 			if (acpi_drv->ops.remove)
 				acpi_drv->ops.remove(acpi_dev);
@@ -1062,7 +1053,7 @@ static void acpi_device_remove(struct device *dev)
 	struct acpi_driver *acpi_drv = to_acpi_driver(dev->driver);
 
 	if (acpi_drv->ops.notify)
-		acpi_device_remove_notify_handler(acpi_dev);
+		acpi_device_remove_notify_handler(acpi_dev, acpi_drv);
 
 	if (acpi_drv->ops.remove)
 		acpi_drv->ops.remove(acpi_dev);