title: Is it possible to call a user-space callback function from kernel space in Linux (ioctl)?
body: <p>Is it possible to expand the ioctl interface in Linux so that the user-space application can send a pointer to a function to the kernel space driver? </p>
  
  <p>I'm in particular thinking of ways to handle the stream in user-controllable way but doing it in the kernel. Those operations could be attached to the kernel module but this would make development a lot easier as I wouldn't need to mess with the kernel during development.</p>
  
  <p>More specifically, this would be the process:</p>
  
  <ol>
  <li>Data is read by the driver to a buffer.</li>
  <li>Data is handled by these user-defined functions in place.</li>
  <li>Some more handling is done, possibly with some HW blocks.</li>
  <li>Data is used by a user-space application.</li>
  </ol>