1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>futex_wait_setup</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 12. Futex API reference"><link rel="prev" href="API-futex-wait-queue-me.html" title="futex_wait_queue_me"><link rel="next" href="API-handle-early-requeue-pi-wakeup.html" title="handle_early_requeue_pi_wakeup"></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">futex_wait_setup</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-futex-wait-queue-me.html">Prev</a> </td><th width="60%" align="center">Chapter 12. Futex API reference</th><td width="20%" align="right"> <a accesskey="n" href="API-handle-early-requeue-pi-wakeup.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-futex-wait-setup"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>futex_wait_setup — 2 Prepare to wait on a futex 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">futex_wait_setup </b>(</code></td><td>u32 __user * <var class="pdparam">uaddr</var>, </td></tr><tr><td> </td><td>u32 <var class="pdparam">val</var>, </td></tr><tr><td> </td><td>unsigned int <var class="pdparam">flags</var>, </td></tr><tr><td> </td><td>struct futex_q * <var class="pdparam">q</var>, </td></tr><tr><td> </td><td>struct futex_hash_bucket ** <var class="pdparam">hb</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idp1124931236"></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 the futex userspace address 5 </p></dd><dt><span class="term"><em class="parameter"><code>val</code></em></span></dt><dd><p> 6 the expected value 7 </p></dd><dt><span class="term"><em class="parameter"><code>flags</code></em></span></dt><dd><p> 8 futex flags (FLAGS_SHARED, etc.) 9 </p></dd><dt><span class="term"><em class="parameter"><code>q</code></em></span></dt><dd><p> 10 the associated futex_q 11 </p></dd><dt><span class="term"><em class="parameter"><code>hb</code></em></span></dt><dd><p> 12 storage for hash_bucket pointer to be returned to caller 13 </p></dd></dl></div></div><div class="refsect1"><a name="idp1124936820"></a><h2>Description</h2><p> 14 Setup the futex_q and locate the hash_bucket. Get the futex value and 15 compare it with the expected value. Handle atomic faults internally. 16 Return with the hb lock held and a q.key reference on success, and unlocked 17 with no q.key reference on failure. 18</p></div><div class="refsect1"><a name="idp1124937668"></a><h2>Return</h2><p> 19 0 - uaddr contains val and hb has been locked; 20 <1 - -EFAULT or -EWOULDBLOCK (uaddr does not contain val) and hb is unlocked 21</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="API-futex-wait-queue-me.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="apiref-futex.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="API-handle-early-requeue-pi-wakeup.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="phrase">futex_wait_queue_me</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> <span class="phrase">handle_early_requeue_pi_wakeup</span></td></tr></table></div></body></html> 22