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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>skb_cow_data</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="Linux Networking and Network Devices APIs" /><link rel="up" href="ch01s02.html" title="Socket Buffer Functions" /><link rel="prev" href="re95.html" title="skb_segment" /><link rel="next" href="re97.html" title="skb_partial_csum_set" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span>skb_cow_data</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re95.html">Prev</a> </td><th width="60%" align="center">Socket Buffer Functions</th><td width="20%" align="right"> <a accesskey="n" href="re97.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="skb_cow_data"><a id="API-skb-cow-data"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>skb_cow_data —
Check that a socket buffer's data buffers are writable
</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">int <b class="fsfunc">skb_cow_data </b>(</code></td><td>struct sk_buff * <var class="pdparam">skb</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">tailbits</var>, </td></tr><tr><td> </td><td>struct sk_buff ** <var class="pdparam">trailer</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Arguments"><a id="id2732369"></a><h2>Arguments</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>skb</code></em></span></dt><dd><p>
The socket buffer to check.
</p></dd><dt><span class="term"><em class="parameter"><code>tailbits</code></em></span></dt><dd><p>
Amount of trailing space to be added
</p></dd><dt><span class="term"><em class="parameter"><code>trailer</code></em></span></dt><dd><p>
Returned pointer to the skb where the <em class="parameter"><code>tailbits</code></em> space begins
</p></dd></dl></div></div><div class="refsect1" title="Description"><a id="id2732434"></a><h2>Description</h2><p>
Make sure that the data buffers attached to a socket buffer are
writable. If they are not, private copies are made of the data buffers
and the socket buffer is set to use these instead.
</p><p>
If <em class="parameter"><code>tailbits</code></em> is given, make sure that there is space to write <em class="parameter"><code>tailbits</code></em>
bytes of data beyond current end of socket buffer. <em class="parameter"><code>trailer</code></em> will be
set to point to the skb in which this space begins.
</p><p>
The number of scatterlist elements required to completely map the
COW'd and extended socket buffer will be returned.
</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="re95.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch01s02.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="re97.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span>skb_segment</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> <span>skb_partial_csum_set</span></td></tr></table></div></body></html>
