On 04/15/2016 07:23 AM, Alex Bennée wrote:
> +#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; \
> + })
How are you thinking this will be used? If a loop like
do {
old = atomic_read (ptr);
new = f(old);
} while (!atomic_bool_cmpxchg(ptr, old, new));
then it's usually helpful to use a weak compare_exchange (s/false/true/ above).
This will produce one loop for ll/sc architectures instead of two.
r~
