Re: [PATCH] log2.h: Macro-ize is_power_of_2() for use in BUILD_BUG_ON

[David Dillow]

On Wed, 2010-01-06 at 12:44 -0800, Roland Dreier wrote:
> > Perhaps we can avoid worrying about that via
> 
>  > #define BUILD_BUG_ON_NOT_POWER_OF_2(n)	\
>  > 	BUILD_BUG_ON((n != 0 && ((n & (n - 1)) == 0)))
> 
> Having something so specific to this particular case makes me feel like
> maybe it's just not worth it.  At least in the case I'm looking at, we
> could just have:
> 
> /*
>  * The code relies on FOO being a power of 2.  If you break this,
>  * you're dumb.
>  */
> #define FOO_SHIFT	6
> #define FOO		(1 << FOO_SHIFT)
> 
> Your thoughts?

I'm fine with that, but now I'll probably be the dumb one to break it
some day in the future.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/