Messages in this thread | | | Date | Tue, 14 Jul 2015 13:24:20 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/5] atomics: add acquire/release/relaxed variants of some atomic operations |
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On Tue, Jul 14, 2015 at 12:08:11PM +0100, Will Deacon wrote: > On Tue, Jul 14, 2015 at 11:58:37AM +0100, Peter Zijlstra wrote:
> > #ifndef atomic_add_return_relaxed > > > > #define atomic_add_return_relaxed atomic_add_return > > /* > > * If one cannot define a more relaxed version, > > * acquire/release are out the window too. > > */ > > #define atomic_add_return_acquire atomic_add_return > > #define atomic_add_return_release atomic_add_return > > > > #else /* relaxed */ > > > > #ifndef atomic_add_return_acquire > > #define atomic_add_return_acquire(args...) \ > > do { \ > > atomic_add_return_relaxed(args); \ > > smp_mb__after_atomic(); \ > > } while (0) > > #endif > > > > #ifndef atomic_add_return_release > > #define atomic_add_return_release(args...) \ > > do { \ > > smp_mb__before_atomic(); \ > > atomic_add_return_relaxed(args); \ > > } while (0) > > #endif
One could even take it one step further and go:
#ifndef atomic_add_return #define atomic_add_return(args...) \ do { \ smp_mb__before_atomic(); \ atomid_add_return_relaxed(args); \ smp_mb__after_atomic(); \ } while (0)
> > > > #endif /* relaxed */ > > If a picture is worth a thousand words, a patch is worth at least a thousand > pictures.
:-)
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