Messages in this thread | | | Date | Mon, 23 Jun 2014 08:54:23 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] arch,locking: Ciao arch_mutex_cpu_relax() |
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On Fri, Jun 20, 2014 at 11:21:13AM -0700, Davidlohr Bueso wrote: > diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h > index d99f9b3..8e1bf6b 100644 > --- a/arch/arc/include/asm/processor.h > +++ b/arch/arc/include/asm/processor.h > @@ -62,6 +62,8 @@ unsigned long thread_saved_pc(struct task_struct *t); > #define cpu_relax() do { } while (0) > #endif > > +#define arch_cpu_relax() cpu_relax() > + > #define copy_segments(tsk, mm) do { } while (0) > #define release_segments(mm) do { } while (0)
I'm not at all sure that cpu_relax() definition ARC has is valid. We rely on cpu_relax() being at least a barrier() all over the place, and it doesn't need to be SMP only. You can have a UP wait loop waiting for an interrupt for example.
Vineet?
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