Re: futex(2) man page update help request

[Andy Lutomirski <luto@amacapital.net>]

On Wed, May 14, 2014 at 1:23 PM, Carlos O'Donell <carlos@redhat.com> wrote:
> On 05/14/2014 03:03 PM, Michael Kerrisk (man-pages) wrote:
>>> However, unless I'm sorely mistaken, the larger problem is that glibc
>>> removed the futex() call entirely, so these man pages don't describe
>>
>> I don't think futex() ever was in glibc--that's by design, and
>> completely understandable: no user-space application would want to
>> directly use futex(). (BTW, I mispoke in my earlier mail when I said I
>> wanted documentation suitable for "writers of library functions" -- I
>> meant suitable for "writers of *C library*".)
>
> I fully agree with Michael here.
>
> The futex() syscall was never exposed to userspace specifically because
> it was an interface we did not want to support forever with a stable ABI.
> The futex() syscall is an implementation detail that is shared between
> the kernel and the writers of core runtimes for Linux.
>
> The fact that the futex() syscall is out of date is my fault, is the fault
> of Linux kernel developers, etc. etc., we should all have reached out to
> Michael with patches to keep this developer-centric documentation updated.

I realize that this is out of scope for linux-abi, but I *stongly*
disagree with this notion.  futex() needs to be just as stable as
anything else: old glibc versions must continue to work.  I just
jumped through a bunch of hoops to keep a single glibc patch release
in OpenSUSE 9 working in a maintainable way; breaking futex will break
far more than that.

Additionally, at least the FUTEX_WAIT and FUTEX_WAKE operations are
extremely useful, and they can do things that are tedious at best
using mutexes and condvars.  It's a simple API to use.  I use it, and
I've seen plenty of other open-source apps using the futex API
directly.

I think the best way forward might be to try to convince the glibc
maintainers to add the wrapper.

--Andy