Messages in this thread | | | From | Vineet Gupta <> | Subject | Re: [PATCH v2 16/19] ARC: [plat-eznps] Use dedicated cpu_relax() | Date | Mon, 9 Nov 2015 10:22:27 +0000 |
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On Monday 09 November 2015 03:35 PM, Peter Zijlstra wrote: > On Sat, Nov 07, 2015 at 12:52:34PM +0200, Noam Camus wrote: >> diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h >> index 7266ede..50f9bae 100644 >> --- a/arch/arc/include/asm/processor.h >> +++ b/arch/arc/include/asm/processor.h >> @@ -58,12 +58,21 @@ struct task_struct; >> * get optimised away by gcc >> */ >> #ifdef CONFIG_SMP >> +#ifndef CONFIG_EZNPS_MTM_EXT >> #define cpu_relax() __asm__ __volatile__ ("" : : : "memory") >> #else >> +#define cpu_relax() \ >> + __asm__ __volatile__ (".word %0" : : "i"(CTOP_INST_SCHD_RW) : "memory") >> +#endif >> +#else >> #define cpu_relax() do { } while (0) > I'm fairly sure this is incorrect. Even on UP we expect cpu_relax() to > be a compiler barrier.
We discussed this a while back (why do https:/lkml.org/lkml/<year>/.... links work psuedo randomly)
http://marc.info/?l=linux-kernel&m=140350765530113
> >> #endif >> >> +#ifndef CONFIG_EZNPS_MTM_EXT >> #define cpu_relax_lowlatency() cpu_relax() >> +#else >> +#define cpu_relax_lowlatency() barrier() >> +#endif > At which point you can unconditionally use that definition. > >> >> #define copy_segments(tsk, mm) do { } while (0) >> #define release_segments(mm) do { } while (0) >> -- >> 1.7.1 >> > _______________________________________________ > linux-snps-arc mailing list > linux-snps-arc@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-snps-arc >
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