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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>ipcctl_pre_down</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="ch05.html#id2654382" title="IPC utilities" /><link rel="prev" href="re254.html" title="ipc_update_perm" /><link rel="next" href="re256.html" title="ipc_parse_version" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span>ipcctl_pre_down</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re254.html">Prev</a> </td><th width="60%" align="center">IPC utilities</th><td width="20%" align="right"> <a accesskey="n" href="re256.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="ipcctl_pre_down"><a id="API-ipcctl-pre-down"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>ipcctl_pre_down —
retrieve an ipc and check permissions for some IPC_XXX cmd
</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">struct kern_ipc_perm * <b class="fsfunc">ipcctl_pre_down </b>(</code></td><td>struct ipc_ids * <var class="pdparam">ids</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">id</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">cmd</var>, </td></tr><tr><td> </td><td>struct ipc64_perm * <var class="pdparam">perm</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">extra_perm</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Arguments"><a id="id2657668"></a><h2>Arguments</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>ids</code></em></span></dt><dd><p>
the table of ids where to look for the ipc
</p></dd><dt><span class="term"><em class="parameter"><code>id</code></em></span></dt><dd><p>
the id of the ipc to retrieve
</p></dd><dt><span class="term"><em class="parameter"><code>cmd</code></em></span></dt><dd><p>
the cmd to check
</p></dd><dt><span class="term"><em class="parameter"><code>perm</code></em></span></dt><dd><p>
the permission to set
</p></dd><dt><span class="term"><em class="parameter"><code>extra_perm</code></em></span></dt><dd><p>
one extra permission parameter used by msq
</p></dd></dl></div></div><div class="refsect1" title="Description"><a id="id2657764"></a><h2>Description</h2><p>
This function does some common audit and permissions check for some IPC_XXX
cmd and is called from semctl_down, shmctl_down and msgctl_down.
It must be called without any lock held and
- retrieves the ipc with the given id in the given table.
- performs some audit and permission check, depending on the given cmd
- returns the ipc with both ipc and rw_mutex locks held in case of success
or an err-code without any lock held otherwise.
</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="re254.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch05.html#id2654382">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="re256.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span>ipc_update_perm</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> <span>ipc_parse_version</span></td></tr></table></div></body></html>
