Here is button for controller action
$block->addButton('generate_label', array(
'label' => Mage::helper('sales')->__('Generate label'),
'onclick' => "setLocation('{$block->getUrl('*/logistics/labelNormal')}')",//if message use: "confirmSetLocation('{$message}', '{$block->getUrl('*/yourmodule/crazy')}')",
'class' => 'go'
));
This is the controller action where i am trying to redirect to previous page.
public function labelNormalAction() { //label action
$order_id = $this->getRequest()->getParam('order_id');
$this->createLabelAction($order_id,false);
$this->_redirectReferer();
return;
}