Re: [Xen-devel] [PATCH v6 02/18] Add cmpxchg16b support for x86-64

["Wu, Feng" <feng.wu@xxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Tuesday, September 08, 2015 4:52 PM
> To: Wu, Feng
> Cc: Andrew Cooper; xen-devel@xxxxxxxxxxxxx; Keir Fraser
> Subject: RE: [PATCH v6 02/18] Add cmpxchg16b support for x86-64
> 
> >>> On 08.09.15 at 09:37, <feng.wu@xxxxxxxxx> wrote:
> > Thanks for your suggestion. How about this?
> >
> > #define cmpxchg16b(ptr,o,n)
> \
> >     ( ({ ASSERT(((unsigned long)ptr & 0xF) == 0); }),                  \
> >       BUILD_BUG_ON(sizeof(*o) != sizeof(__uint128_t)),
> \
> >       BUILD_BUG_ON(sizeof(*n) != sizeof(__uint128_t)),
> \
> >       __cmpxchg16b((ptr), (__uint128_t *)(o), (__uint128_t *)(n)) )
> 
> Yes (properly parenthesized and the ({ }) either removed or extended

We need the ({ }) for the ASSERT statement, or we will meet build error.

Thanks,
Feng

> to the whole expression).
> 
> Jan


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