Re: [PATCH v2 14/22] arm64: Cleanup HWCAP handling

From: Russell King - ARM Linux
Date: Thu Oct 08 2015 - 07:17:29 EST


On Thu, Oct 08, 2015 at 12:10:00PM +0100, Catalin Marinas wrote:
> On Mon, Oct 05, 2015 at 06:02:03PM +0100, Suzuki K. Poulose wrote:
> > +static bool cpus_have_hwcap(const struct arm64_cpu_capabilities *cap)
> > +{
> > + switch(cap->hwcap_type) {
> > + case CAP_HWCAP:
> > + return !!(elf_hwcap & cap->hwcap);
> > +#ifdef CONFIG_COMPAT
> > + case CAP_COMPAT_HWCAP:
> > + return !!(compat_elf_hwcap & (u32)cap->hwcap);
> > + case CAP_COMPAT_HWCAP2:
> > + return !!(compat_elf_hwcap2 & (u32)cap->hwcap);
> > +#endif
> > + default:
> > + BUG();
> > + return false;
> > + }
> > +}
>
> Apart from the multiple returns, you don't really need !! since the
> return type is bool already.

That's wrong. a & b doesn't return 0 or 1, but the bitwise-and result.

http://yarchive.net/comp/linux/bool.html

especially hpa's response.

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