hp_accel: fix race in device removal

The work queue has to be flushed after the device has been made
inaccessible.  The patch closes a window during which a work queue might
remain active after the device is removed and would then lead to ACPI
calls with undefined behavior.
Signed-off-by: Oliver Neukum <oneukum@suse.de>
Acked-by: Eric Piel <eric.piel@tremplin-utc.net>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: Pavel Herrmann <morpheus.ibis@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/hwmon/hp_accel.c

@@ -328,8 +328,8 @@ static int lis3lv02d_remove(struct acpi_device *device, int type)
 	lis3lv02d_joystick_disable();
 	lis3lv02d_poweroff(&lis3_dev);
 
-	flush_work(&hpled_led.work);
 	led_classdev_unregister(&hpled_led.led_classdev);
+	flush_work(&hpled_led.work);
 
 	return lis3lv02d_remove_fs(&lis3_dev);
 }