Re: [PATCH v2 1/7] atomics: add acquire/release/relaxed variants of some atomic operations

Will Deacon
2015-07-17T09:40:22Z

Hi Waiman,

On Fri, Jul 17, 2015 at 01:07:28AM +0100, Waiman Long wrote:
> On 07/16/2015 11:32 AM, Will Deacon wrote:
> > +#ifndef atomic64_add_return_relaxed
> > +#define atomic64_add_return_relaxed atomic64_add_return
> > +#define atomic64_add_return_acquire atomic64_add_return
> > +#define atomic64_add_return_release atomic64_add_return
> > +
> > +#else /* atomic64_add_return_relaxed */
> > +
> > +#ifndef atomic64_add_return_acquire
> > +#define atomic64_add_return_acquire(...) \
> > + __atomic_op_acquire(long long, atomic64_add_return, __VA_ARGS__)
> > +#endif
> > +
> > +#ifndef atomic64_add_return_release
> > +#define atomic64_add_return_release(...) \
> > + __atomic_op_release(long long, atomic64_add_return, __VA_ARGS__)
> > +#endif
> > +
> > +#ifndef atomic64_add_return
> > +#define atomic64_add_return(...) \
> > + __atomic_op_fence(long long, atomic64_add_return, __VA_ARGS__)
> > +#endif
> > +#endif /* atomic64_add_return_relaxed */
> > +
>
> I have a minor nit. The atomic_add_return block is repeated with
> "s/atomic_add_return/.../". Perhaps some more comments to delineate the
> blocks more visibly will make this patch easier to read.

Yeah, I agree that it's pretty hard going, but I don't have any great
suggestions to solve that. I could add an extra blank line + comment
before the start of each section, if you like? Example snippet below.

Will

--->8

[...]
#endif /* atomic_sub_return_relaxed */

/* atomic_xchg_relaxed */
#ifndef atomic_xchg_relaxed
#define atomic_xchg_relaxed atomic_xchg
#define atomic_xchg_acquire atomic_xchg
#define atomic_xchg_release atomic_xchg

#else /* atomic_xchg_relaxed */

#ifndef atomic_xchg_acquire
#define atomic_xchg_acquire(...) \
__atomic_op_acquire(int, atomic_xchg, __VA_ARGS__)
#endif

#ifndef atomic_xchg_release
#define atomic_xchg_release(...) \
__atomic_op_release(int, atomic_xchg, __VA_ARGS__)
#endif

#ifndef atomic_xchg
#define atomic_xchg(...) \
__atomic_op_fence(int, atomic_xchg, __VA_ARGS__)
#endif
#endif /* atomic_xchg_relaxed */

/* atomic_cmpxchg_relaxed */ …