Upload File CI

$idSiswa = "6304194";
if (($_FILES["userfile"]["name"] == "") || (!isset($_FILES["userfile"]["name"]))) {
        $photo = "";
      } else {
        $config['upload_path'] = './media/product/';
        $config['allowed_types'] = 'gif|jpg|png';
        $config['max_size'] = '10000';
        $extensi = $_FILES["userfile"]["name"];
        $extensi = explode(".", $extensi);
        $config['file_name'] = $idSiswa."_". $_FILES["userfile"]["name"] . "." . $extensi[1];
        $config['file_path'] = $_FILES["userfile"]["tmp_name"];
        $this->load->library('upload', $config);
        $this->upload->initialize($config);
        if (!$this->upload->do_upload()) {
          $photo = "";
          $error = array('error' => $this->upload->display_errors());
        } else {
          $photo = $config['file_name'];
        }
      }

echo $photo;