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.
Paolo
> + nr -= bits_to_set;
> + bits_to_set = BITS_PER_LONG;
> + mask_to_set = ~0UL;
> + p++;
> + }
> + if (nr) {
> + mask_to_set &= BITMAP_LAST_WORD_MASK(size);
> + atomic_or(p, mask_to_set);
> + }
> +}
> +
