Re: [PATCH v2 2/2] io: prevent compiler reordering on the default readX() implementation

Arnd Bergmann
2018-04-04T15:55:39Z

On Wed, Apr 4, 2018 at 5:52 PM, Sinan Kaya <okaya@codeaurora.org> wrote:
> On 4/3/2018 6:29 PM, Palmer Dabbelt wrote:
>>
>
> Are we looking for something like this?

Yes, exactly, plus the same for write and in/out of course.

> diff --git a/inc
> #ifndef readb
> #define readb readb
> -static inline u8 readb(const volatile void __iomem *addr)
> -{
> - return __raw_readb(addr);
> -}
> +#define readb(c) \
> + ({ u8 __v; \
> + __io_br(); \
> + __v = __raw_readb(c); \
> + __io_ar(); \
> + __v; })
> #endif

I would prefer leaving these as inline functions, but that's only
a cosmetic difference.

Arnd