osfmk/man/io_done_queue_wait.html

   1 <h2>io_done_queue_wait</h2>
   2 <hr>
   3 <p>
   4 <strong>System Trap</strong> - Wait on an io_done_queue kernel object.
   5 <h3>SYNOPSIS</h3>
   6 <pre>
   7 <strong>kern_return_t   io_done_queue_wait</strong>
   8                 <strong>(mach_port_t</strong>             <var>queue</var>,
   9                 <strong>io_done_result_t</strong>       <var>*result</var><strong>);</strong>
  10 </pre>
  11 <h3>PARAMETERS</h3>
  12 <dl>
  13 <p>
  14 <dt> <var>queue</var>
  15 <dd>
  16 [in io-done-queue send right] The port referencing the io_done_queue
  17 to be destroyed.
  18 <p>
  19 <dt> <var>result</var>
  20 <dd>
  21 [out structure] The data structure to be filled in with the completion
  22 status of the I/O operation.
  23 </dl>
  24 <h3>DESCRIPTION</h3>
  25 <p>
  26 The <strong>io_done_queue_wait</strong> interface is called to obtain the results of a
  27 previously requested asynchronous I/O operation. For each
  28 <strong>io_done_queue_wait</strong> invocation, the status of one I/O request is
  29 returned. If there are no pending I/O completions, io_done_queue_wait
  30 blocks in the kernel on the address of the completion queue. The
  31 mKernel, from interrupt context, enqueues (in FIFO order) completions
  32 (struct <strong>io_done_result</strong>'s) on the completion queue and posts a wakeup
  33 on the queue for each I/O completion. Completion processing previously
  34 done by the mKernel <strong>io_done thread</strong> is now done by the task thread when
  35 it awakens.
  36 <h3>RETURN VALUES</h3>
  37 <dl>
  38   <dt> <strong>KERN_TERMINATED</strong>
  39 <dd>
  40      Stale <strong>io_done_queue</strong> handle.
  41      <p>
  42
  43   <dt> <strong>KERN_INVALID_ARGUMENT</strong>
  44 <dd>
  45      Invalid <var>queue</var> parameter.
  46      <p>
  47 <dt> <strong>KERN_INVALID_ARGUMENT</strong>
  48 <dd>
  49      The <var>result</var> parameter is a bad address.
  50      <p>
  51 </dl>
  52 <h3>RELATED INFORMATION</h3>
  53 <p>
  54 Functions:
  55 <a href="io_done_queue_create.html"><strong>io_done_queue_create</strong></a>,
  56 <a href="io_done_queue_wait.html"><strong>io_done_queue_wait</strong></a>,
  57 <a href="device_read_async.html"><strong>device_read_async</strong></a>,
  58 <a href="device_read_async_inband.html"><strong>device_read_async_inband</strong></a>,
  59 <a href="DR_overwrite_async.html"><strong>device_read_overwrite_async</strong></a>,
  60 <a href="device_write_async.html"><strong>device_write_async</strong></a>,
  61 <a href="device_write_async_inband.html"><strong>device_write_async_inband</strong></a>.