title: Unload kext which still has instances
body: <p>I'm updating the driver of one of my devices and would like to kextunload the old driver and kextload the new one so a restart isn't required anymore.</p>
  
  <p>After the installation I try:</p>
  
  <pre><code>sudo kextunload /System/Library/Extensions/Driver.kext
  </code></pre>
  
  <p>The error which happens looks like this:</p>
  
  <blockquote>
    <p>(kernel) Can't unload kext com.driver.Driver; classes have instances:
    (kernel)     Kext com.driver.Driver class com_driver_Driver_USBAudioDevice has 1 instance.
    Failed to unload com.driver.Driver - (libkern/kext) kext is in use or retained (cannot unload).</p>
  </blockquote>
  
  <p>The device is not present in ioreg. 
  How can I find out what this instance is which prevents me from unloading the driver?</p>