Drupal 7 function to get all users with specific role(s)

use_load_multiple_by_role.php

/**
 * get all users with specific role(s)
 *
 * @param int|int[] $role_id
 *   role id for role
 *
 * @return object[]
 *   user objects with given role(s)
 */
function user_load_multiple_by_role($role_id) {
  if (is_int($role_id)) {
    $role_id = array($role_id);
  }

  $user_ids = db_select('users_roles', 'ur')
    ->fields('ur', array('uid'))
    ->condition('rid', $role_id, 'IN')
    ->execute()
    ->fetchCol();

  return (count($user_ids) > 0) ? entity_load('user', $user_ids): array();
}