From: Darren Hart <dvhart@linux.intel.com>
To: <mtk.manpages@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
Jakub Jelinek <jakub@redhat.com>,
"linux-man@vger.kernel.org" <linux-man@vger.kernel.org>,
lkml <linux-kernel@vger.kernel.org>,
Davidlohr Bueso <davidlohr.bueso@hp.com>,
Arnd Bergmann <arnd@arndb.de>,
Steven Rostedt <rostedt@goodmis.org>,
Peter Zijlstra <peterz@infradead.org>,
Linux API <linux-api@vger.kernel.org>,
"Carlos O'Donell" <carlos@redhat.com>
Subject: Re: futex(2) man page update help request
Date: Wed, 14 May 2014 12:59:16 -0700 [thread overview]
Message-ID: <CF991864.9074F%dvhart@linux.intel.com> (raw)
In-Reply-To: <CAKgNAkh+PWzT2SByaLk_OtiAXeZSkWoMgu+ivDOt1dTWVtaatQ@mail.gmail.com>
On 5/14/14, 12:03, "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
wrote:
>Hi Darren,
>
>On Wed, May 14, 2014 at 6:18 PM, Darren Hart <dvhart@linux.intel.com>
>wrote:
>> On 5/14/14, 3:35, "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
>> wrote:
>>
>>>[So, some futex recent discussions remind me I should make this request]
>>>
>>>Hello all (especially those in the To:, namely Thomas, Darren, Ingo,
>>>Jakub),
>>>
>>>The futex man pages:
>>>http://man7.org/linux/man-pages/man2/futex.2.html
>>>http://man7.org/linux/man-pages/man7/futex.7.html
>>>are currently in a sorry state. I'm by no means convinced that all of
>>>the
>>>futex operations described there are explained fully and correctly. And
>>>probably not all error cases for each operation are properly documented.
>>>I'd be very happy if some folk could review those pages and send me
>>>corrections (Git:
>>>http://git.kernel.org/pub/scm/docs/man-pages/man-pages).
>>>
>>>But worse, a number of futex operations remain undocumented in futex(2)
>>>(see the list below).
>>>
>>>I am aware of Documentation/pi-futex.txt and
>>>Documentation/futex-requeue-pi.txt. However, both of those documents
>>>are rather thin on details / explain what certain FUTEX_* operations are
>>>used for rather than what they do / focus on the implementation, rather
>>>than the semantics.
>>>
>>>What I would like is that the futex(2) page documenta each one of
>>>these operations with a focus on the semantics in a way that might be
>>>useful to writers of library functions or those who simply wish to
>>>better understand (from a user-space perspective) what futexes are
>>>and how they are used. However, I don't have the knowledge to do
>>>this well in any reasonable time.
>>>
>>>Would the folk in the To: list (or anyone else who is knowledgeable)
>>>be willing to write patches
>>>(Git: http://git.kernel.org/pub/scm/docs/man-pages/man-pages )
>>>or just supply me with some raw text that documents these currently
>>>undocumented futex operations, in the manner suggested?
>>
>> Yes, I'll be glad to help.
>
>Thanks!
>
>> 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*".)
>
>> something users even have access to anymore. I had to revert to calling
>> the syscalls directly in the futextest test suite because of this:
>>
>>
>>http://git.kernel.org/cgit/linux/kernel/git/dvhart/futextest.git/tree/inc
>>lu
>> de/futextest.h#n67
>>
>>
>> Which basically defines:
>>
>> #define futex(uaddr, op, val, timeout, uaddr2, val3, opflags) \
>> syscall(SYS_futex, uaddr, op | opflags, val, timeout, uaddr2,
>>val3)
>>
>>
>> Adding Carlos for his perspective.
>>
>> If I'm wrong, or we can restore the futex() call, great. If not...
>>Should
>> we keep the man-pages and document it as syscall(SYS_futex, ..., op,
>>...) ?
>
>We should keep the man page ;-). I just need to add some words to
>point out the use of syscall(). Mostly though, I'm interested in
>getting documentation of the operations listed below :-).
OK, yes - because the following doesn't work:
#include <linux/futex.h>
#include <sys/time.h>
int futex(int *uaddr, int op, int val, const struct timespec
*timeout,
int *uaddr2, int val3);
It's going to be difficult for me to make the time to do this - but I do
want it done, so please don't hesitate to nag me.
Thanks,
>>> commit 4732efbeb997189d9f9b04708dc26bf8613ed721
>>> Author: Jakub Jelinek <jakub@redhat.com>
>>> Date: Tue Sep 6 15:16:25 2005 -0700
>>> See also https://bugzilla.kernel.org/show_bug.cgi?id=14303
>>>
>>>2.6.18 adds priority inheritance support:
>>>FUTEX_LOCK_PI, FUTEX_UNLOCK_PI, and FUTEX_TRYLOCK_PI.
>>> commit c87e2837be82df479a6bae9f155c43516d2feebc
>>> Author: Ingo Molnar <mingo@elte.hu>
>>> Date: Tue Jun 27 02:54:58 2006 -0700
>>>
>>> commit e2970f2fb6950183a34e8545faa093eb49d186e1
>>> Author: Ingo Molnar <mingo@elte.hu>
>>> Date: Tue Jun 27 02:54:47 2006 -0700
>>>
>>> See Documentation/pi-futex.txt
>>>
>>>2.6.25 adds FUTEX_WAKE_BITSET, FUTEX_WAIT_BITSET
>>> commit cd689985cf49f6ff5c8eddc48d98b9d581d9475d
>>> Author: Thomas Gleixner <tglx@linutronix.de>
>>> Date: Fri Feb 1 17:45:14 2008 +0100
>>>
>>>2.6.31 adds FUTEX_WAIT_REQUEUE_PI, FUTEX_CMP_REQUEUE_PI
>>> commit 52400ba946759af28442dee6265c5c0180ac7122
>>> Author: Darren Hart <dvhltc@us.ibm.com>
>>> Date: Fri Apr 3 13:40:49 2009 -0700
>>>
>>> commit ba9c22f2c01cf5c88beed5a6b9e07d42e10bd358
>>> Author: Darren Hart <dvhltc@us.ibm.com>
>>> Date: Mon Apr 20 22:22:22 2009 -0700
>>>
>>> See Documentation/futex-requeue-pi.txt
>>>
>>>Thanks,
>>>
>>>Michael
>>>
>>>
>>>--
>>>Michael Kerrisk
>>>Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
>>>Linux/UNIX System Programming Training: http://man7.org/training/
>>>
>>
>>
>> --
>> Darren Hart Open Source Technology
>>Center
>> darren.hart@intel.com Intel
>>Corporation
>>
>>
>>
>
>
>
>--
>Michael Kerrisk
>Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
>Linux/UNIX System Programming Training: http://man7.org/training/
>
--
Darren Hart Open Source Technology Center
darren.hart@intel.com Intel Corporation
next prev parent reply other threads:[~2014-05-14 19:59 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-14 10:35 futex(2) man page update help request Michael Kerrisk (man-pages)
2014-05-14 16:18 ` Darren Hart
2014-05-14 19:03 ` Michael Kerrisk (man-pages)
2014-05-14 19:59 ` Darren Hart [this message]
2014-05-14 20:23 ` Carlos O'Donell
2014-05-14 20:44 ` Andy Lutomirski
2014-05-14 23:34 ` Thomas Gleixner
2014-05-15 3:12 ` Carlos O'Donell
2014-05-15 4:49 ` Michael Kerrisk (man-pages)
2014-05-15 4:53 ` Michael Kerrisk (man-pages)
2014-05-15 14:14 ` Thomas Gleixner
2014-05-15 20:19 ` Michael Kerrisk (man-pages)
2014-08-04 14:46 ` Carlos O'Donell
2014-05-15 20:35 ` Darren Hart
2015-01-15 15:12 ` Michael Kerrisk (man-pages)
2015-01-17 1:33 ` Darren Hart
2015-01-17 9:16 ` Michael Kerrisk (man-pages)
2015-01-17 19:26 ` Darren Hart
2015-01-18 10:18 ` Michael Kerrisk (man-pages)
2015-01-15 15:10 ` Michael Kerrisk (man-pages)
2015-01-15 22:23 ` Thomas Gleixner
2015-01-16 15:17 ` Michael Kerrisk (man-pages)
2015-01-16 15:20 ` Thomas Gleixner
2015-01-16 20:54 ` Michael Kerrisk (man-pages)
2015-01-17 0:46 ` Darren Hart
2015-01-19 10:45 ` Thomas Gleixner
2015-01-19 14:07 ` Michael Kerrisk (man-pages)
2015-01-23 18:19 ` Torvald Riegel
2015-01-24 10:05 ` Thomas Gleixner
2015-01-24 12:58 ` Torvald Riegel
2015-01-24 16:25 ` Thomas Gleixner
2015-01-17 0:56 ` Davidlohr Bueso
2015-01-17 1:11 ` Darren Hart
2015-01-23 18:29 ` Torvald Riegel
2015-01-24 11:35 ` Thomas Gleixner
2015-01-24 13:12 ` Torvald Riegel
2015-01-27 7:48 ` Michael Kerrisk (man-pages)
2015-02-05 19:57 ` Darren Hart
2014-05-15 8:13 ` Peter Zijlstra
2014-05-15 15:43 ` Darren Hart
2014-05-15 8:14 ` Peter Zijlstra
2014-05-15 13:18 ` Carlos O'Donell
2014-05-15 13:22 ` Peter Zijlstra
2014-05-15 13:49 ` Michael Kerrisk (man-pages)
2014-05-15 13:55 ` Peter Zijlstra
2014-05-15 14:39 ` Carlos O'Donell
2014-05-15 15:11 ` Peter Zijlstra
2014-05-14 20:56 ` Davidlohr Bueso
2014-05-14 21:03 ` Darren Hart
2014-05-14 22:21 ` Paul E. McKenney
2014-05-15 0:28 ` H. Peter Anvin
2014-05-15 0:35 ` Andy Lutomirski
2014-05-15 0:41 ` H. Peter Anvin
2014-05-15 19:10 ` Carlos O'Donell
2014-05-14 21:05 ` Davidlohr Bueso
2014-05-15 15:15 ` Joseph S. Myers
2014-05-15 0:18 ` H. Peter Anvin
2014-05-15 5:21 ` Darren Hart
2014-05-15 8:23 ` Peter Zijlstra
2014-05-15 13:46 ` Michael Kerrisk (man-pages)
2014-05-15 14:59 ` H. Peter Anvin
2014-05-15 15:42 ` chrubis
2014-05-15 15:52 ` H. Peter Anvin
2014-05-15 16:01 ` chrubis
2014-05-15 16:07 ` H. Peter Anvin
2014-05-15 16:17 ` chrubis
2014-05-15 16:56 ` H. Peter Anvin
2014-05-15 17:06 ` chrubis
2014-05-15 15:47 ` Darren Hart
2014-05-15 15:35 ` chrubis
2014-05-15 15:28 ` chrubis
2014-05-15 15:40 ` Steven Rostedt
2014-05-15 16:14 ` Darren Hart
2014-05-15 16:30 ` chrubis
2014-05-15 18:17 ` Darren Hart
2014-05-15 19:05 ` chrubis
2014-05-15 19:38 ` Darren Hart
2014-08-11 10:19 ` chrubis
2014-11-26 13:41 ` Cyril Hrubis
2015-02-16 13:14 ` Cyril Hrubis
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