Editing Futex (section)

== {{Anchor|BENAPHORE}}History ==
Hubertus Franke ([[IBM]] [[Thomas J. Watson Research Center]]), Matthew Kirkwood, [[Ingo Molnár]] ([[Red Hat]]), and [[Rusty Russell]] ([[IBM Linux Technology Center]]) originated the futex mechanism on [[Linux]] in 2002.
<ref>
"Fuss, Futexes and Furwocks: Fast Userlevel Locking in Linux" by Franke, Russell, Kirkwood. Published in 2002 for the Ottawa Linux Symposium.
</ref> In the same year, discussions took place on a proposal to make futexes accessible via the file system by creating a special node in <code>/dev</code> or <code>/proc</code>. However, [[Linus Torvalds]] strongly opposed this idea and rejected any related patches.<ref>
{{cite web|last=Torvalds|first=Linus|title=Futex Asynchronous Interface
|url=http://yarchive.net/comp/linux/everything_is_file.html}}
</ref>

Futexes then appeared for the first time in version 2.5.7 of the Linux kernel development series; the semantics stabilized as of version 2.5.40, and futexes have been part of the [[Linux kernel mainline]] since the December 2003 release of 2.6.x stable kernel series.

Futex functionality has been implemented in Microsoft Windows since Windows 8 or Windows Server 2012 under the name '''WaitOnAddress'''.<ref>
{{cite web| url= https://docs.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-waitonaddress 
| title=WaitOnAddress function | access-date=2019-11-01}}
</ref>

In 2013, Microsoft patented futex-related<ref>
{{cite web
| url= https://devblogs.microsoft.com/oldnewthing/20170601-00/?p=96265
| title= Comparing WaitOnAddress with futexes
| access-date=2024-05-09}}
</ref> '''WaitOnAddress''' and the patent was granted in 2014.<ref>
{{cite web| url= https://patents.google.com/patent/US8782674B2/en 
| title=US8782674B2 Wait on address synchronization interface | access-date=2019-11-01}}
</ref>
  
In May 2014, the [[Common Vulnerabilities and Exposures|CVE]] system announced a vulnerability discovered in the Linux kernel's futex subsystem that allowed denial-of-service attacks or local privilege escalation.<ref>
[http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-3153 CVE-2014-3153]
</ref><ref>
{{cite web| url= https://lists.debian.org/debian-security-announce/2014/msg00130.html 
| title=[SECURITY&#93; [DSA 2949-1&#93; linux security update |publisher=Lists.debian.org 
| date=2014-06-05 |access-date=2014-06-08}}
</ref>

In May 2015, the [[Kernel (operating system)|Linux kernel]] introduced a deadlock bug via [https://github.com/torvalds/linux/commit/b0c29f79ecea Commit b0c29f79ecea] that caused a hang in user applications. The bug affected many enterprise Linux distributions, including 3.x and 4.x kernels, and Red Hat Enterprise Linux version 5, 6 and 7, SUSE Linux 12 and Amazon Linux.<ref>
{{cite web| url= https://groups.google.com/forum/#!topic/mechanical-sympathy/QbmpZxp6C64
| title=Linux futex_wait() bug...
| date=2015-05-13 |access-date=2018-03-24}}
</ref>

Futexes have been implemented in [[OpenBSD]] since 2016.<ref>{{cite web|last1=Mazurek|first1=Michal|title='Futexes for OpenBSD' - MARC|url=https://marc.info/?l=openbsd-tech&m=147282346309815&w=2|website=marc.info|access-date=30 April 2017}}</ref>

The futex mechanism is one of the core concepts of the Zircon kernel<ref>{{cite web|title=Zircon Kernel Concepts|url=https://fuchsia.dev/fuchsia-src/zircon/concepts#futexes|website=fuchsia.dev|access-date=20 October 2019}}</ref> in [[Google]]'s [[Fuchsia (operating system)|Fuchsia operating system]] since at least April 2018.<ref>{{cite web|title=zx_futex_wait|url=https://fuchsia.dev/fuchsia-src/reference/syscalls/futex_wait|website=fuchsia.dev|access-date=20 October 2019}}</ref>

Apple implemented futex in iOS/iPadOS/tvOS 17.4, macOS 14.4, watchOS 10.4 and visionOS 1.1.<ref>{{Cite web |title=os_sync_wait_on_address |url=https://developer.apple.com/documentation/os/os_sync_wait_on_address |access-date=2025-04-14 |website=Apple Developer Documentation |language=en-US}}</ref>

Futex like functionality was added to [[C++]] with the <code>atomic::wait</code>, <code>atomic::notify_one</code>, and <code>atomic::notify_all</code> operations in [[C++20]].

Support for FUTEX2 in the Linux kernel was designed to support two new main features, first something that can be used to implement the Win32 API '''WaitForMultipleObjects''', and second to be able to wait on addresses other  than 32bit ones. The first step was integrated in 5.16 in November 2021.<ref>{{cite web|title=FUTEX2's sys_futex_waitv() Sent In For Linux 5.16 To Help Linux Gaming|url=https://www.phoronix.com/news/Linux-5.16-sys_futex_waitv|access-date=23 May 2025}}</ref> with the waitv syscall.