[PATCH 1/2] score: Add _Per_CPU_Get_snapshot()

[Gedare Bloom]

On Fri, Apr 11, 2014 at 11:15 AM, Sebastian Huber
<sebastian.huber at embedded-brains.de> wrote:
> ---
>  cpukit/score/include/rtems/score/percpu.h |    8 +++++---
>  1 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/cpukit/score/include/rtems/score/percpu.h b/cpukit/score/include/rtems/score/percpu.h
> index 75ff3e2..92a6e8a 100644
> --- a/cpukit/score/include/rtems/score/percpu.h
> +++ b/cpukit/score/include/rtems/score/percpu.h
> @@ -424,11 +424,13 @@ extern Per_CPU_Control_envelope _Per_CPU_Information[] CPU_STRUCTURE_ALIGNMENT;
>    _ISR_Enable( isr_cookie )
>  #endif
>
> +#define _Per_CPU_Get_snapshot() \
> +  ( &_Per_CPU_Information[ _SMP_Get_current_processor() ].per_cpu )
> +
I think of a snapshot as a copy of some data that might change in the
future. Since this gets the reference without making even a
shallow-copy, I don't know what is being "snapshotted" or what
guarantees if any are made about the snapshot.

>  #if defined( RTEMS_SMP )
>  static inline Per_CPU_Control *_Per_CPU_Get( void )
>  {
> -  Per_CPU_Control *per_cpu =
> -    &_Per_CPU_Information[ _SMP_Get_current_processor() ].per_cpu;
> +  Per_CPU_Control *per_cpu = _Per_CPU_Get_snapshot();
>
>    _Assert(
>      per_cpu->thread_dispatch_disable_level != 0 || _ISR_Get_level() != 0
> @@ -437,7 +439,7 @@ static inline Per_CPU_Control *_Per_CPU_Get( void )
>    return per_cpu;
>  }
>  #else
> -#define _Per_CPU_Get() ( &_Per_CPU_Information[ 0 ].per_cpu )
> +#define _Per_CPU_Get() _Per_CPU_Get_snapshot()
>  #endif
>
>  static inline Per_CPU_Control *_Per_CPU_Get_by_index( uint32_t index )
> --
> 1.7.7
>
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