Re: Access through cast to volatile

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

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Am Sonntag, den 17.05.2015, 21:21 +0300 schrieb Alexander Monakov:
> On Sun, 17 May 2015, Jens Gustedt wrote:
> > > > I only recently learned that even cast to volatile doesn't help in
> > > > cases where the original object to which p points is not declared
> > > > volatile. The C standard states that only volatile *declared* objects
> > > > are subject to the rules of volatile. Accessing through a volatile
> > > > pointer doesn't help.
> > > 
> > > I'm not so sure about that.
> > 
> > I am quite sure. We recently had a discussion on that in the
> > committee, and the outcome was basically what I was stating above.
> 
> Was the Linux kernel's use of volatile cast in its ACCESS_ONCE macro
> discussed?

yes

But the Linux kernel uses stronger properties than are given by the C
standard. It is in many parts built upon assumptions about gcc and its
extensions.

> (I realize it's offtopic, but I hope it's acceptable)

I don't think it is offtopic, we have to be sure what assumptions we
want to make.

Jens


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