Re: [PATCH] x86/cpuidle: publish new states only after fully initializing them

[Andrew Cooper <andrew.cooper3@citrix.com>]

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On 10/12/13 15:26, Jan Beulich wrote:
> Since state information coming from Dom0 can arrive at any time, on
> any CPU, we ought to make sure that a new state is fully initialized
> before the target CPU might be using it.
>
> Once touching that code, also do minor cleanup: A missing (but benign)
> "break" and some white space adjustments.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

>
> --- a/xen/arch/x86/acpi/cpu_idle.c
> +++ b/xen/arch/x86/acpi/cpu_idle.c
> @@ -912,7 +912,7 @@ static void set_cx(
>                     acpi_power->cpu, xen_cx->type);
>              return;
>          }
> -        cx = &acpi_power->states[acpi_power->count++];
> +        cx = &acpi_power->states[acpi_power->count];
>          cx->type = xen_cx->type;
>          break;
>      }
> @@ -937,11 +937,14 @@ static void set_cx(
>          break;
>      default:
>          cx->entry_method = ACPI_CSTATE_EM_NONE;
> +        break;
>      }
>  
> -    cx->latency  = xen_cx->latency;
> -    
> +    cx->latency = xen_cx->latency;
>      cx->target_residency = cx->latency * latency_factor;
> +
> +    smp_wmb();
> +    acpi_power->count++;
>      if ( cx->type == ACPI_STATE_C1 || cx->type == ACPI_STATE_C2 )
>          acpi_power->safe_state = cx;
>  }
>
>
>
>
>
> _______________________________________________
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> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel


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