Re: [Qemu-devel] [RFC v1 05/12] atomic: introduce cmpxchg_bool

["Alex Bennée" <alex.bennee@linaro.org>]

Sergey Fedorov <serge.fdrv@gmail.com> writes:

> On 15/04/16 17:23, Alex Bennée wrote:
>> diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h
>> index 5dba7db..94e7110 100644
>> --- a/include/qemu/atomic.h
>> +++ b/include/qemu/atomic.h
>> @@ -123,6 +123,16 @@
>>      _old;                                                               \
>>      })
>>
>> +#define atomic_bool_cmpxchg(ptr, old, new)                              \
>> +    ({                                                                  \
>> +    typeof(*ptr) _old = (old), _new = (new);                            \
>> +    bool r;                                                             \
>> +    r = __atomic_compare_exchange(ptr, &_old, &_new, false,             \
>> +                                  __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);  \
>> +    r;                                                                  \
>> +    })
>> +
>> +
>
> Could be more simple:
>
> #define atomic_bool_cmpxchg(ptr, old, new)                              \
>     ({                                                                  \
>     typeof(*ptr) _old = (old), _new = (new);                            \
>     __atomic_compare_exchange(ptr, &_old, &_new, false,                 \
>                               __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);      \
>     })

OK that makes sense. I'll have to ask my toolchain colleague what the
rules are for results from {} blocks.

--
Alex Bennée