Avalon doesn't like losing its device data even after it's been unplugged.

driver-avalon.c

@@ -1611,8 +1611,6 @@ static void avalon_shutdown(struct thr_info *thr)
 	mutex_destroy(&info->lock);
 	free(avalon->works);
 	avalon->works = NULL;
-	free(avalon->device_data);
-	avalon->device_data = NULL;
 }
 
 static char *avalon_set_device(struct cgpu_info *avalon, char *option, char *setting, char *replybuf)