Re: {put,get}_user() side effects

[Horst von Brand]

Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> said:
> On Tue, 6 Apr 2004, Andi Kleen wrote:
> > Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> writes:
> > > On most (all?) architectures {get,put}_user() has side effects:
> > >
> > > #define put_user(x,ptr)                                                 \
> > >   __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
> >
> > Neither typeof not sizeof are supposed to have side effects. If your
> > compiler generates them that's a compiler bug.

> From a simple compile test, you seem to be right... Weird, since it does
> expand to 3 times 'pIndex++', but pIndex is incremented only once.

Better check with a C language lawyer. Maybe gcc gets it wrong, or it is
undefined (in which case next gcc could screw you over, and give you a hard
time finding out how...). An inline should be safe, and unless gcc still
gets them wrong, equally fast/small.
-- 
Dr. Horst H. von Brand                   User #22616 counter.li.org
Departamento de Informatica                     Fono: +56 32 654431
Universidad Tecnica Federico Santa Maria              +56 32 654239
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