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Re: [PATCH] Unify pthread_once (bug 15215)
- From: Torvald Riegel <triegel at redhat dot com>
- To: Rich Felker <dalias at aerifal dot cx>
- Cc: GLIBC Devel <libc-alpha at sourceware dot org>, libc-ports <libc-ports at sourceware dot org>
- Date: Fri, 10 May 2013 10:30:57 +0200
- Subject: Re: [PATCH] Unify pthread_once (bug 15215)
- References: <1368024237 dot 7774 dot 794 dot camel at triegel dot csb> <20130508175132 dot GB20323 at brightrain dot aerifal dot cx> <1368046046 dot 7774 dot 1441 dot camel at triegel dot csb> <20130508212502 dot GF20323 at brightrain dot aerifal dot cx> <1368088765 dot 7774 dot 1571 dot camel at triegel dot csb> <20130509140245 dot GI20323 at brightrain dot aerifal dot cx> <1368112468 dot 7774 dot 2082 dot camel at triegel dot csb> <20130509155613 dot GM20323 at brightrain dot aerifal dot cx>
On Thu, 2013-05-09 at 11:56 -0400, Rich Felker wrote:
> On Thu, May 09, 2013 at 05:14:28PM +0200, Torvald Riegel wrote:
> > > > I agree that the absence of a proper memory model makes reasoning about
> > > > some of this hard. I guess it would be best if POSIX would just endorse
> > > > C11's memory model, and specify the intended semantics in relation to
> > > > this model where needed.
> > >
> > > Agreed, and I suspect this is what they'll do. I can raise the issue,
> > > but perhaps you'd be better at expressing it. Let me know if you'd
> > > rather I do it.
> >
> > I have no idea how the POSIX folks would feel about this. After all, it
> > would create quite a dependency for POSIX. With that in mind, trying to
> > resolve this isn't very high on my todo list. If people would think
> > that this would be beneficial for how we can deal with POSIX
> > requirements, or for our users to understand the POSIX requirements
> > better, I can definitely try to follow up on this. If you want to go
> > ahead and start discussing with them, please do so (please CC me on the
> > tracker bug).
>
> POSIX is aligned with ISO C, and since the current version of ISO C is
> now the 2011 version, Issue 8 should be aligned to the 2011 version of
> the C standard. I don't think the issue is whether it happens, but
> making sure that the relevant text gets updated so that there's no
> ambiguity as to whether it's compatible with the new C standard and
> not placing unwanted additional implementation constraints like it may
> be doing now.
So, if it is aligned, would POSIX be willing to base their definitions
on the C11 memory model? Or would they want to keep their sometimes
rather vague requirements and just make sure that there are no obvious
inconsistencies or gaps?
Torvald