On Tue, 2011-07-26 at 00:09 -0700, Linus Torvalds wrote:
> On Mon, Jul 25, 2011 at 11:51 PM, Nicholas A. Bellinger
> <nab@xxxxxxxxxxxxxxx> wrote:
> >
> > How about the following to add a new DIV_ROUND_UP_ULL macro
>
> Hmm.
>
> > #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
> > +#define DIV_ROUND_UP_ULL(n,d) ( \
> > +{ \
> > + unsigned long long _tmp = n, _off; \
> > + int _res; \
> > + /* Round up using asm/div64.h:do_div */ \
> > + _off = do_div(_tmp, d); \
> > + if (_off != 0) \
> > + _tmp++; \
> > + _res = _tmp; \
> > +} \
> > +)
>
> That looks buggy. Why the "_res = _tmp" there? All that does is to
> truncate the result to "int", which looks bogus.
>
> And it just looks unnecessarily complicated. Just a simple
>
> #define DIV_ROUND_UP_ULL(ll,d) \
> ({ unsigned long long _tmp = (ll)+(d)-1; do_div(_tmp, d); _tmp; })
>
> looks like it would work and be simpler. Avoid the conditional, do the
> same "add 'd-1' thing as the regular ROUND_UP().
>
> Untested. And not much thinking involved.
>
Fixing this up in lio-core-2.6.git now and pushing out into
target-pending.git/for-next now unless you have any other concerns.
Thank you,
--nab
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