Wrong number of total submissions

The module close the form when max allowed number of submissions is reached on the next form load, but if two user submit the form at the same time the code not check if form is already close.
So, if you want to stop users submission when effectively max allowed number of submissions is reached, add this function before function webform_limit_submissions_nodeapi:

/**
 * Handle webform's submission on presave op
 */
function webform_limit_submissions_webform_submission_presave($node, &$submission) {
 // Get the value for the limit of submissions
      $max_submissions = _webform_limit_submissions_get_value($node->nid);
      
      // Check if max submissions has been set or isn't equal to zero
      if ($max_submissions > 0) {
        // Count the current total of submissions in the database
        $count = db_result(db_query('SELECT count(*) FROM {webform_submissions} WHERE nid = %d', $node->nid));
        // Check if the current total of submissions is equal or higher than the value we provided
        if ($count >= $max_submissions) {
        	header('Location: /node/' . $node->nid);
        	exit;
        }	
      }
}

This function check if max allowed number of submissions is reached on presave operation (as nodeapi definition http://api.drupal.org/api/drupal/developer--hooks--core.php/function/hoo...). If the limit is reached the node is reloaded without insert the data in the database and the "close message" appears.