'\" t
.\"     Title: skb_cow_data
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: May 2018
.\"    Manual: Linux Networking
.\"    Source: Kernel Hackers Manual 3.16.56
.\"  Language: English
.\"
.TH "SKB_COW_DATA" "9" "May 2018" "Kernel Hackers Manual 3\&.16\&" "Linux Networking"
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.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
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.SH "NAME"
skb_cow_data \- Check that a socket buffer\*(Aqs data buffers are writable
.SH "SYNOPSIS"
.HP \w'int\ skb_cow_data('u
.BI "int skb_cow_data(struct\ sk_buff\ *\ " "skb" ", int\ " "tailbits" ", struct\ sk_buff\ **\ " "trailer" ");"
.SH "ARGUMENTS"
.PP
\fIskb\fR
.RS 4
The socket buffer to check\&.
.RE
.PP
\fItailbits\fR
.RS 4
Amount of trailing space to be added
.RE
.PP
\fItrailer\fR
.RS 4
Returned pointer to the skb where the
\fItailbits\fR
space begins
.RE
.SH "DESCRIPTION"
.PP
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\&.
.PP
If
\fItailbits\fR
is given, make sure that there is space to write
\fItailbits\fR
bytes of data beyond current end of socket buffer\&.
\fItrailer\fR
will be set to point to the skb in which this space begins\&.
.PP
The number of scatterlist elements required to completely map the COW\*(Aqd and extended socket buffer will be returned\&.
.SH "COPYRIGHT"
.br