osfmk/man/io_done_queue_wait.html

   1 <h2>io_done_queue_wait</h2>
<hr>
<p>
<strong>System Trap</strong> - Wait on an io_done_queue kernel object.
<h3>SYNOPSIS</h3>
<pre>
<strong>kern_return_t       io_done_queue_wait</strong>
            <strong>(mach_port_t</strong>             <var>queue</var>,
            <strong>io_done_result_t</strong>       <var>*result</var><strong>);</strong>
</pre>
<h3>PARAMETERS</h3>
<dl>
<p>
<dt> <var>queue</var>
<dd>
[in io-done-queue send right] The port referencing the io_done_queue 
to be destroyed.
<p>
<dt> <var>result</var>
<dd>
[out structure] The data structure to be filled in with the completion
status of the I/O operation.
</dl>
<h3>DESCRIPTION</h3>
<p>
The <strong>io_done_queue_wait</strong> interface is called to obtain the results of a
previously requested asynchronous I/O operation. For each
<strong>io_done_queue_wait</strong> invocation, the status of one I/O request is
returned. If there are no pending I/O completions, io_done_queue_wait
blocks in the kernel on the address of the completion queue. The
mKernel, from interrupt context, enqueues (in FIFO order) completions
(struct <strong>io_done_result</strong>'s) on the completion queue and posts a wakeup
on the queue for each I/O completion. Completion processing previously
done by the mKernel <strong>io_done thread</strong> is now done by the task thread when
it awakens.
<h3>RETURN VALUES</h3>
<dl>
  <dt> <strong>KERN_TERMINATED</strong>
<dd>
     Stale <strong>io_done_queue</strong> handle.
     <p>

  <dt> <strong>KERN_INVALID_ARGUMENT</strong>
<dd>
     Invalid <var>queue</var> parameter.
     <p>
<dt> <strong>KERN_INVALID_ARGUMENT</strong>
<dd>
     The <var>result</var> parameter is a bad address.
     <p>
</dl>
<h3>RELATED INFORMATION</h3>
<p>
Functions:
<a href="io_done_queue_create.html"><strong>io_done_queue_create</strong></a>,
<a href="io_done_queue_wait.html"><strong>io_done_queue_wait</strong></a>,
<a href="device_read_async.html"><strong>device_read_async</strong></a>,
<a href="device_read_async_inband.html"><strong>device_read_async_inband</strong></a>,
<a href="DR_overwrite_async.html"><strong>device_read_overwrite_async</strong></a>,
<a href="device_write_async.html"><strong>device_write_async</strong></a>,
<a href="device_write_async_inband.html"><strong>device_write_async_inband</strong></a>.