Re: [PATCH v3 00/17] Cross-architecture definitions of relaxed MMIO accessors

From: Arnd Bergmann
Date: Thu Sep 25 2014 - 15:19:56 EST

On Thursday 25 September 2014, Daniel Thompson wrote:
> > +
> > +#ifndef readq_relaxed
> > +#define readq_relaxed readq
> > +#endif
> Not really sure if it matters but this gives a rather surprising
> behaviour to #ifdef readq_relaxed given that readq may not be defined.

It was intentional. I could have written this as

#if !defined(readq_relaxed) && defined(readq)

but the effect would be almost the same, and the version I picked looks
simpler. Note that 32-bit architectures could provide readq, it's just
the generic code that doesn't, because most you typically don't get
atomic 64-bit accesses from dereferencing a 64-bit pointer as the
generic readq() function does.

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