On Thu, Nov 27, 2014 at 05:42:41PM +0100, Paolo Bonzini wrote:
>
>
> On 27/11/2014 13:29, Stefan Hajnoczi wrote:
> > +void bitmap_set_atomic(unsigned long *map, long start, long nr)
> > +{
> > + unsigned long *p = map + BIT_WORD(start);
> > + const long size = start + nr;
> > + int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
> > + unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
> > +
> > + while (nr - bits_to_set >= 0) {
> > + atomic_or(p, mask_to_set);
>
> atomic_or is unnecessary while mask_to_set is ~0UL. I think not even a
> smp_wmb() is necessary.Okay, I can split this into the ~0UL case and the atomic case.
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