Messages in this thread | | | Subject | Re: [PATCHv3 04/10] linux/kernel: introduce lower_48_bits macro | From | Joe Perches <> | Date | Tue, 22 Feb 2022 08:58:56 -0800 |
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On Tue, 2022-02-22 at 17:50 +0100, Christoph Hellwig wrote: > On Tue, Feb 22, 2022 at 08:45:53AM -0800, Joe Perches wrote: > > On Tue, 2022-02-22 at 08:31 -0800, Keith Busch wrote: > > > Recent data integrity field enhancements allow 48-bit reference tags. > > > Introduce a helper macro since this will be a repeated operation. > > [] > > > diff --git a/include/linux/kernel.h b/include/linux/kernel.h > > [] > > > @@ -63,6 +63,12 @@ > > > } \ > > > ) > > > > > > +/** > > > + * lower_48_bits - return bits 0-47 of a number > > > + * @n: the number we're accessing > > > + */ > > > +#define lower_48_bits(n) ((u64)((n) & 0xffffffffffffull)) > > > > why not make this a static inline function? > > Agreed. > > > And visually, it's difficult to quickly count a repeated character to 12. > > > > Perhaps: > > > > static inline u64 lower_48_bits(u64 val) > > { > > return val & GENMASK_ULL(47, 0); > > } > > For anyone who has a minimum knowledge of C and hardware your version > is an obsfucated clusterfuck, while the version Keith wrote is > trivial to read.
Don't think so. I've dealt with hardware and have more than once seen defects introduced by firmware developers that can't count.
be quick, which one is it:
0xfffffffffffULL or 0xffffffffffffULL or 0xfffffffffffffULL or 0xffffffffffffffULL
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