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

From	Russell King - ARM Linux <linux@arm.linux.org.uk>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 14/22] arm64: Cleanup HWCAP handling
Date	2015-10-08 13:20 +0200
Message-ID	<qhhoS-1PL-37@gated-at.bofh.it> (permalink)
References	<qghqV-5ar-3@gated-at.bofh.it> <qghqY-5ar-55@gated-at.bofh.it> <qhhoS-1PL-39@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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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Re: [PATCH v2 14/22] arm64: Cleanup HWCAP handling Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-08 13:20 +0200
  Re: [PATCH v2 14/22] arm64: Cleanup HWCAP handling Catalin Marinas <catalin.marinas@arm.com> - 2015-10-08 15:10 +0200
    Re: [PATCH v2 14/22] arm64: Cleanup HWCAP handling Edward Nevill <edward.nevill@linaro.org> - 2015-10-08 17:00 +0200

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