1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>relay_open</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="relayfs.html#idp1125442764" title="relay interface"><link rel="prev" href="API-relay-reset.html" title="relay_reset"><link rel="next" href="API-relay-switch-subbuf.html" title="relay_switch_subbuf"></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">relay_open</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-relay-reset.html">Prev</a> </td><th width="60%" align="center">relay interface</th><td width="20%" align="right"> <a accesskey="n" href="API-relay-switch-subbuf.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-relay-open"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>relay_open — 2 create a new relay channel 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">struct rchan * <b class="fsfunc">relay_open </b>(</code></td><td>const char * <var class="pdparam">base_filename</var>, </td></tr><tr><td> </td><td>struct dentry * <var class="pdparam">parent</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">subbuf_size</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">n_subbufs</var>, </td></tr><tr><td> </td><td>struct rchan_callbacks * <var class="pdparam">cb</var>, </td></tr><tr><td> </td><td>void * <var class="pdparam">private_data</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idp1125464500"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>base_filename</code></em></span></dt><dd><p> 4 base name of files to create, <code class="constant">NULL</code> for buffering only 5 </p></dd><dt><span class="term"><em class="parameter"><code>parent</code></em></span></dt><dd><p> 6 dentry of parent directory, <code class="constant">NULL</code> for root directory or buffer 7 </p></dd><dt><span class="term"><em class="parameter"><code>subbuf_size</code></em></span></dt><dd><p> 8 size of sub-buffers 9 </p></dd><dt><span class="term"><em class="parameter"><code>n_subbufs</code></em></span></dt><dd><p> 10 number of sub-buffers 11 </p></dd><dt><span class="term"><em class="parameter"><code>cb</code></em></span></dt><dd><p> 12 client callback functions 13 </p></dd><dt><span class="term"><em class="parameter"><code>private_data</code></em></span></dt><dd><p> 14 user-defined data 15 </p></dd></dl></div></div><div class="refsect1"><a name="idp1125471740"></a><h2>Description</h2><p> 16 Returns channel pointer if successful, <code class="constant">NULL</code> otherwise. 17 </p><p> 18 19 Creates a channel buffer for each cpu using the sizes and 20 attributes specified. The created channel buffer files 21 will be named base_filename0...base_filenameN-1. File 22 permissions will be <code class="constant">S_IRUSR</code>. 23</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="API-relay-reset.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="relayfs.html#idp1125442764">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="API-relay-switch-subbuf.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="phrase">relay_reset</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">relay_switch_subbuf</span></td></tr></table></div></body></html> 24