On Wed, Jul 04, 2018 at 05:37:23PM +0100, Mark Rutland wrote:
> On Wed, Jul 04, 2018 at 04:24:22PM +0100, Will Deacon wrote:
> > This is mostly straightforward, but the cmpxchg/cmpxchg_double cases grow
> > an 'arch' prefix which suggests that they're part of the API with the core
> > atomics and also makes them horribly ugly.
>
> I agree this isn't nice.
>
> > This just looks to be an artifact of __LL_SC_CALL pasting that in. Can
> > you drop that auto pasting of 'arch', and instead change the
> > non-cmpxchg-case callers of the macro to include the arch prefix
> > instead, please?
>
> That leads to having an arch___llsc_ prefix in some cases, which is
> equally hideous.
Yuck, how does that come about?
> How about I remove the prefix mangling entirely, and always give
> functions an __llsc_ or __lse_ prefix. Then, unify the two in our
> atomic.h with:
>
> #ifdef CONFIG_ARM64_LSE
> #define ATOMIC_PFX __lse_
> #else
> #define ATOMIC_PFX __ll_sc_
> #endif
>
> #define arch_atomic_foo ATOMIC_PFX##atomic_foo
> #define arch_atomic_bar ATOMIC_PFX##atomic_bar
>
> ... which clearly delineates the implementation from core API.
>
> Does that sound ok to you?
Why do we need two prefixes? The only reason we throw out __ll_sc_ at the
moment is so the out-of-line atomics have a different name from the inlined
ones. What I'd like is:
atomic_foo
-> arch_atomic_foo
-> optionally calls __ll_sc_arch_atomic_foo
which I think is very similar to what we already do (i.e. the inlined macro
is always called arch_atomic_foo, regardless of lse or ll/sc).
Will
