'\" t
.\"     Title: _copy_from_user
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: January 2017
.\"    Manual: Memory Management in Linux
.\"    Source: Kernel Hackers Manual 4.8.15
.\"  Language: English
.\"
.TH "_COPY_FROM_USER" "9" "January 2017" "Kernel Hackers Manual 4\&.8\&." "Memory Management in Linux"
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.SH "NAME"
_copy_from_user \- Copy a block of data from user space\&.
.SH "SYNOPSIS"
.HP \w'unsigned\ long\ _copy_from_user('u
.BI "unsigned long _copy_from_user(void\ *\ " "to" ", const\ void\ __user\ *\ " "from" ", unsigned\ " "n" ");"
.SH "ARGUMENTS"
.PP
\fIto\fR
.RS 4
Destination address, in kernel space\&.
.RE
.PP
\fIfrom\fR
.RS 4
Source address, in user space\&.
.RE
.PP
\fIn\fR
.RS 4
Number of bytes to copy\&.
.RE
.SH "CONTEXT"
.PP
User context only\&. This function may sleep if pagefaults are enabled\&.
.SH "DESCRIPTION"
.PP
Copy data from user space to kernel space\&.
.PP
Returns number of bytes that could not be copied\&. On success, this will be zero\&.
.PP
If some data could not be copied, this function will pad the copied data to the requested size using zero bytes\&.
.SH "COPYRIGHT"
.br