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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>__clear_user</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="The Linux Kernel API" /><link rel="up" href="ch04s02.html" title="User Space Memory Access" /><link rel="prev" href="re146.html" title="clear_user" /><link rel="next" href="re148.html" title="strnlen_user" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span>__clear_user</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re146.html">Prev</a> </td><th width="60%" align="center">User Space Memory Access</th><td width="20%" align="right"> <a accesskey="n" href="re148.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="__clear_user"><a id="API---clear-user"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>__clear_user —
Zero a block of memory in user space, with less checking.
</p></div><div class="refsynopsisdiv" title="Synopsis"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">unsigned long <b class="fsfunc">__clear_user </b>(</code></td><td>void __user * <var class="pdparam">to</var>, </td></tr><tr><td> </td><td>unsigned long <var class="pdparam">n</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Arguments"><a id="id2971767"></a><h2>Arguments</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>to</code></em></span></dt><dd><p>
Destination address, in user space.
</p></dd><dt><span class="term"><em class="parameter"><code>n</code></em></span></dt><dd><p>
Number of bytes to zero.
</p></dd></dl></div></div><div class="refsect1" title="Description"><a id="id2971811"></a><h2>Description</h2><p>
Zero a block of memory in user space. Caller must check
the specified block with <code class="function">access_ok</code> before calling this function.
</p><p>
Returns number of bytes that could not be cleared.
On success, this will be zero.
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