<?xml version="1.0" encoding="ANSI_X3.4-1968" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>try_module_get()/module_put() include/linux/module.h</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="Unreliable Guide To Hacking The Linux Kernel" /><link rel="up" href="ch06.html" title="Chapter 6. Common Routines" /><link rel="prev" href="ch06s12.html" title="module_exit() include/linux/init.h" /><link rel="next" href="ch07.html" title="Chapter 7. Wait Queues include/linux/wait.h" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"> <code class="function">try_module_get()</code>/<code class="function">module_put()</code> <code class="filename">include/linux/module.h</code></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch06s12.html">Prev</a> </td><th width="60%" align="center">Chapter 6. Common Routines</th><td width="20%" align="right"> <a accesskey="n" href="ch07.html">Next</a></td></tr></table><hr /></div><div class="sect1" title="try_module_get()/module_put() include/linux/module.h"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="routines-module-use-counters"></a> <code class="function">try_module_get()</code>/<code class="function">module_put()</code> <code class="filename">include/linux/module.h</code></h2></div></div></div><p> These manipulate the module usage count, to protect against removal (a module also can't be removed if another module uses one of its exported symbols: see below). Before calling into module code, you should call <code class="function">try_module_get()</code> on that module: if it fails, then the module is being removed and you should act as if it wasn't there. Otherwise, you can safely enter the module, and call <code class="function">module_put()</code> when you're finished. </p><p> Most registerable structures have an <em class="structfield"><code>owner</code></em> field, such as in the <span class="structname">file_operations</span> structure. Set this field to the macro <span class="symbol">THIS_MODULE</span>. </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch06s12.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch06.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ch07.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"> <code class="function">module_exit()</code> <code class="filename">include/linux/init.h</code>  </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 7. Wait Queues <code class="filename">include/linux/wait.h</code> </td></tr></table></div></body></html>