1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>list_empty_careful</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="The Linux Kernel API"><link rel="up" href="adt.html#idp1119950572" title="Doubly Linked Lists"><link rel="prev" href="API-list-empty.html" title="list_empty"><link rel="next" href="API-list-rotate-left.html" title="list_rotate_left"></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">list_empty_careful</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-list-empty.html">Prev</a>&#160;</td><th width="60%" align="center">Doubly Linked Lists</th><td width="20%" align="right">&#160;<a accesskey="n" href="API-list-rotate-left.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-list-empty-careful"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>list_empty_careful &#8212; 
2     tests whether a list is empty and not being modified
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">list_empty_careful </b>(</code></td><td>const struct list_head * <var class="pdparam">head</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer">&#160;</div></div></div><div class="refsect1"><a name="idp1122266828"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>head</code></em></span></dt><dd><p>
4     the list to test
5    </p></dd></dl></div></div><div class="refsect1"><a name="idp1122268356"></a><h2>Description</h2><p>
6   tests whether a list is empty _and_ checks that no other CPU might be
7   in the process of modifying either member (next or prev)
8</p></div><div class="refsect1"><a name="idp1122269076"></a><h2>NOTE</h2><p>
9   using <code class="function">list_empty_careful</code> without synchronization
10   can only be safe if the only activity that can happen
11   to the list entry is <code class="function">list_del_init</code>. Eg. it cannot be used
12   if another CPU could re-<code class="function">list_add</code> it.
13</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="API-list-empty.html">Prev</a>&#160;</td><td width="20%" align="center"><a accesskey="u" href="adt.html#idp1119950572">Up</a></td><td width="40%" align="right">&#160;<a accesskey="n" href="API-list-rotate-left.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="phrase">list_empty</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">list_rotate_left</span></td></tr></table></div></body></html>
14