linux-kernel - Re: futex(2) man page update help request

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Message-ID: <CF9A2F18.90E61%dvhart@linux.intel.com>
Date:	Thu, 15 May 2014 08:47:12 -0700
From:	Darren Hart <dvhart@...ux.intel.com>
To:	"Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, Jakub Jelinek <jakub@...hat.com>
CC:	"linux-man@...r.kernel.org" <linux-man@...r.kernel.org>,
	lkml <linux-kernel@...r.kernel.org>,
	Davidlohr Bueso <davidlohr.bueso@...com>,
	Arnd Bergmann <arnd@...db.de>,
	Steven Rostedt <rostedt@...dmis.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Linux API <linux-api@...r.kernel.org>,
	Carlos O'Donell <carlos@...hat.com>
Subject: Re: futex(2) man page update help request

On 5/15/14, 6:46, "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
wrote:

>On 05/15/2014 07:21 AM, Darren Hart wrote:
>> On 5/14/14, 17:18, "H. Peter Anvin" <hpa@...or.com> wrote:
>> 
>>> On 05/14/2014 09:18 AM, Darren Hart 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
>>>> 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/i
>>>>nc
>>>> lu
>>>> de/futextest.h#n67
>>>>
>>>
>>> This really comes down to the fact that we should have a libinux which
>>> contains the basic system call wrapper machinery for Linux specific
>>> things and nothing else.
>>>
>>> syscall(3) is toxic and breaks randomly on some platforms.
>> 
>> Peter Z and I have had a good time discussing this in the past.... And
>> here it is again. :-)
>
>People have a number of times noted that there are problems
>with syscall(), but I'm not knowledgeable on the details.
>I'd happily take a patch to the man page (which, for historical
>reasons, is actually syscall(2)) that explains the the problems
>(and ideally notes those platforms where there are no problems).


>From my perspective, a named interface with specific documented interfaces
is far more usable than a vargs direct syscall. That just leaves all kinds
of room for error - which of course is why we all write our own wrappers
in our apps rather than use it directly... If we all do it, it seems to me
that is a strong indicator we should provide it in some kind of common
library. Maybe that's libc... Maybe that's libnix...
-- 
Darren Hart					Open Source Technology Center
darren.hart@...el.com				            Intel Corporation



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