title: How to find the implementation of a specific 'ioctl' call?
body: <p>Where can I find the file which includes the implementation of the following ioctl call: </p>
  
  <pre><code>ioctl(dpriv-&gt;fd, IOCTL_USBFS_SUBMITURB, urb);
  #define IOCTL_USBFS_SUBMITURB _IOR('U', 10, struct usbfs_urb)
  </code></pre>
  
  <p>file descriptor is for a usb device. </p>