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SubjectRe: [PATCH 0/3] virtio/vringh: kill off ACCESS_ONCE()
On Fri, Nov 25, 2016 at 01:44:04PM +0100, Peter Zijlstra wrote:
> On Fri, Nov 25, 2016 at 01:40:44PM +0100, Peter Zijlstra wrote:
> > #define SINGLE_LOAD(x) \
> > {( \
> > compiletime_assert_atomic_type(typeof(x)); \
>
> Should be:
>
> compiletime_assert_atomic_type(x);
>
> > WARN_SINGLE_COPY_ALIGNMENT(&(x)); \

Do we need to worry about the side effect on x? Maybe

#define SINGLE_LOAD(x) \
({ \
typeof(x) *_____ptr; \
\
compiletime_assert_atomic_type(typeof(x)); \
\
_____ptr = &(x); \
\
WARN_SINGLE_COPY_ALIGNMENT(_____ptr); \
\
READ_ONCE(*_____ptr); \
})

Ditto for SINGLE_STORE()

Regards,
Boqun

> > READ_ONCE(x); \
> > })
> >
> > #define SINGLE_STORE(x, v) \
> > ({ \
> > compiletime_assert_atomic_type(typeof(x)); \
>
> idem
>
> > WARN_SINGLE_COPY_ALIGNMENT(&(x)); \
> > WRITE_ONCE(x, v); \
> > })

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