1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>usb_kill_urb</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="The Linux-USB Host Side API"><link rel="up" href="usbcore.html" title="Chapter&#160;5.&#160;USB Core APIs"><link rel="prev" href="API-usb-unlink-urb.html" title="usb_unlink_urb"><link rel="next" href="API-usb-poison-urb.html" title="usb_poison_urb"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span class="phrase">usb_kill_urb</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-usb-unlink-urb.html">Prev</a>&#160;</td><th width="60%" align="center">Chapter&#160;5.&#160;USB Core APIs</th><td width="20%" align="right">&#160;<a accesskey="n" href="API-usb-poison-urb.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-usb-kill-urb"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>usb_kill_urb &#8212; 
2     cancel a transfer request and wait for it to finish
3 </p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">void <b class="fsfunc">usb_kill_urb </b>(</code></td><td>struct urb * <var class="pdparam">urb</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer">&#160;</div></div></div><div class="refsect1"><a name="idp1116016172"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>urb</code></em></span></dt><dd><p>
4     pointer to URB describing a previously submitted request,
5     may be NULL
6    </p></dd></dl></div></div><div class="refsect1"><a name="idp1116017796"></a><h2>Description</h2><p>
7   This routine cancels an in-progress request.  It is guaranteed that
8   upon return all completion handlers will have finished and the URB
9   will be totally idle and available for reuse.  These features make
10   this an ideal way to stop I/O in a <code class="function">disconnect</code> callback or <code class="function">close</code>
11   function.  If the request has not already finished or been unlinked
12   the completion handler will see urb-&gt;status == -ENOENT.
13   </p><p>
14
15   While the routine is running, attempts to resubmit the URB will fail
16   with error -EPERM.  Thus even if the URB's completion handler always
17   tries to resubmit, it will not succeed and the URB will become idle.
18   </p><p>
19
20   The URB must not be deallocated while this routine is running.  In
21   particular, when a driver calls this routine, it must insure that the
22   completion handler cannot deallocate the URB.
23   </p><p>
24
25   This routine may not be used in an interrupt context (such as a bottom
26   half or a completion handler), or when holding a spinlock, or in other
27   situations where the caller can't <code class="function">schedule</code>.
28   </p><p>
29
30   This routine should not be called by a driver after its disconnect
31   method has returned.
32</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="API-usb-unlink-urb.html">Prev</a>&#160;</td><td width="20%" align="center"><a accesskey="u" href="usbcore.html">Up</a></td><td width="40%" align="right">&#160;<a accesskey="n" href="API-usb-poison-urb.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="phrase">usb_unlink_urb</span>&#160;</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">&#160;<span class="phrase">usb_poison_urb</span></td></tr></table></div></body></html>
33