Re: [PATCH 24/24] document volatile atomic_read() behavior

[Segher Boessenkool]

> Historically this has been
> +accomplished by declaring the counter itself to be volatile, but the
> +ambiguity of the C standard on the semantics of volatile make this 
> practice
> +vulnerable to overly creative interpretation by compilers.

It's even worse when accessing through a volatile casted pointer;
see for example the recent(*) GCC bugs in that area.

(*) Well, not _all_ that recent.  No one should be using the 3.x
series anymore, right?

> Explicit
> +casting in atomic_read() ensures consistent behavior across 
> architectures
> +and compilers.

Even modulo compiler bugs, what makes you believe that?


Segher

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