title: unlocked_ioctl vs normal ioctl
body: <p>In my driver's file_operations structure, I have:</p>
  
  <pre><code>struct file_operations Fops = {
    read:    device_read,
    write:   device_write,
    unlocked_ioctl:   device_ioctl,
    ...
  };
  </code></pre>
  
  <p>I.e. there is no ioctl field used. Is this sufficient to avoid Big Kernel Lock and enter into device_ioctl() without any synchronization? Or do I have to change ioctl() calls in userspace part of the code too?</p>