Re: C threads, v. 6.2

[Jens Gustedt <jens.gustedt@inria.fr>]

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Am Samstag, den 30.08.2014, 22:44 -0400 schrieb Rich Felker:
> On Sat, Aug 30, 2014 at 09:31:11PM -0400, Rich Felker wrote:
> > On Sat, Aug 30, 2014 at 08:30:34PM -0400, Rich Felker wrote:
> > > > For the C thread TU, what would be the mechanics for them to call one
> > > > of the (aliased) pthread functions?
> > > 
> > > With my alternate solution just described, simply including the normal
> > > pthread header and casting the pointer when making the call would be
> > > fully legal.
> > > 
> > > With the approach we previously discussed, where we have to ensure
> > > that no TU that accesses the contents of a mutex or cv structure can
> > > see both the C11 and POSIX versions, The C11 TUs would have to contain
> > > prototypes for the aliased POSIX functions like:
> > > 
> > > int __pthread_mutex_lock(mtx_t *);
> > > 
> > > Note that this is a perfectly correct prototype because mtx_t is just
> > > this TU's typedef name for the tagless "struct { union { ... } __u; }"
> > > that it's using, which is "the same type" as pthread_mutex_lock.c's
> > > pthread_mutex_t.
> > 
> > Actually, unless the C11 functions actually access the mutex object,
> > their implementation files don't need to avoid having both types
> > visible. Only the TUs that dereference the object (i.e. the pthread
> > ones) need to ensure that only one version of the type is visible.
> 
> The more I think about it, the more I think the visibility of the
> other type is utterly irrelevant.

Yes, inside the C thread implementation it is. So as you have seen I
already came to the same conclusion, and so I applied that idea to the
latest series of patches.

I think this discussion is settled, then.

Jens


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