Re: [PATCH] Unify pthread_once (bug 15215)

[Torvald Riegel <triegel@redhat.com>]

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