1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>fault_in_user_writeable</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="Unreliable Guide To Locking"><link rel="up" href="apiref-futex.html" title="Chapter&#160;12.&#160;Futex API reference"><link rel="prev" href="API-get-futex-key.html" title="get_futex_key"><link rel="next" href="API-futex-top-waiter.html" title="futex_top_waiter"></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">fault_in_user_writeable</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-get-futex-key.html">Prev</a>&#160;</td><th width="60%" align="center">Chapter&#160;12.&#160;Futex API reference</th><td width="20%" align="right">&#160;<a accesskey="n" href="API-futex-top-waiter.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-fault-in-user-writeable"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>fault_in_user_writeable &#8212; 
2     Fault in user address and verify RW access
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">int <b class="fsfunc">fault_in_user_writeable </b>(</code></td><td>u32 __user * <var class="pdparam">uaddr</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer">&#160;</div></div></div><div class="refsect1"><a name="idp1124802348"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>uaddr</code></em></span></dt><dd><p>
4     pointer to faulting user space address
5    </p></dd></dl></div></div><div class="refsect1"><a name="idp1124803932"></a><h2>Description</h2><p>
6   Slow path to fixup the fault we just took in the atomic write
7   access to <em class="parameter"><code>uaddr</code></em>.
8   </p><p>
9
10   We have no generic implementation of a non-destructive write to the
11   user address. We know that we faulted in the atomic pagefault
12   disabled section so we can as well avoid the #PF overhead by
13   calling <code class="function">get_user_pages</code> right away.
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