'\" t
.\"     Title: get_futex_key
.\"    Author: 
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: May 2018
.\"    Manual: Futex API reference
.\"    Source: Kernel Hackers Manual 3.16.56
.\"  Language: English
.\"
.TH "GET_FUTEX_KEY" "9" "May 2018" "Kernel Hackers Manual 3\&.16\&" "Futex API reference"
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.SH "NAME"
get_futex_key \- Get parameters which are the keys for a futex
.SH "SYNOPSIS"
.HP \w'int\ get_futex_key('u
.BI "int get_futex_key(u32\ __user\ *\ " "uaddr" ", int\ " "fshared" ", union\ futex_key\ *\ " "key" ", int\ " "rw" ");"
.SH "ARGUMENTS"
.PP
\fIuaddr\fR
.RS 4
virtual address of the futex
.RE
.PP
\fIfshared\fR
.RS 4
0 for a PROCESS_PRIVATE futex, 1 for PROCESS_SHARED
.RE
.PP
\fIkey\fR
.RS 4
address where result is stored\&.
.RE
.PP
\fIrw\fR
.RS 4
mapping needs to be read/write (values: VERIFY_READ, VERIFY_WRITE)
.RE
.SH "RETURN"
.PP
a negative error code or 0
.PP
The key words are stored in *key on success\&.
.PP
For shared mappings, it\*(Aqs (page\->index, file_inode(vma\->vm_file), offset_within_page)\&. For private mappings, it\*(Aqs (uaddr, current\->mm)\&. We can usually work out the index without swapping in the page\&.
.PP
\fBlock_page\fR
might sleep, the caller should not hold a spinlock\&.
.SH "AUTHOR"
.PP
\fBRusty Russell\fR <\&rusty@rustcorp.com.au\&>
.RS 4
Author.
.RE
.SH "COPYRIGHT"
.br