[PATCH 1/2] taskmode.c: Ensure all error checking is done before modifying executing

[Sebastian Huber]

On 05/12/17 17:13, Joel Sherrill wrote:
> Also use single conditional expressions to simplify error checking.
> Combined, this all resulted in a block of SMP enabled error checking.
>
> Updates #3000.
> ---
>   cpukit/rtems/src/taskmode.c | 33 +++++++++++++++++++++++++++++++--
>   1 file changed, 31 insertions(+), 2 deletions(-)
>
> diff --git a/cpukit/rtems/src/taskmode.c b/cpukit/rtems/src/taskmode.c
> index a345409..49648ac 100644
> --- a/cpukit/rtems/src/taskmode.c
> +++ b/cpukit/rtems/src/taskmode.c
> @@ -43,6 +43,33 @@ rtems_status_code rtems_task_mode(
>     if ( !previous_mode_set )
>       return RTEMS_INVALID_ADDRESS;
>   
> +#if defined( RTEMS_SMP )
> +  /*
> +   * When in SMP, you cannot disable preemption for a thread or
> +   * alter its interrupt level. It must be fully preemptible with
> +   * all interrupts enabled.
> +   */
> +  if ( rtems_configuration_is_smp_enabled() ) {
> +    if ( mask & RTEMS_PREEMPT_MASK ) {
> +      if ( !_Modes_Is_preempt( mode_set ) ) {
> +        return RTEMS_NOT_IMPLEMENTED;
> +      }
> +    }
> +
> +    if ( mask & RTEMS_INTERRUPT_MASK ) {
> +      if (_Modes_Get_interrupt_level( mode_set ) != 0 ) {

if ( _Modes...

> +        return RTEMS_NOT_IMPLEMENTED;
> +      }

There should be a test case for the new else path 
_Modes_Get_interrupt_level( mode_set ) == 0.

> +    }
> +  }
> +#endif
> +
> +  /*
> +   * Complete all error checking before doing any operations which
> +   * impact the executing thread. There should be no errors returned
> +   * past this point.
> +   */
> +
>     executing     = _Thread_Get_executing();
>     api = executing->API_Extensions[ THREAD_API_RTEMS ];
>     asr = &api->Signal;
> @@ -63,18 +90,18 @@ rtems_status_code rtems_task_mode(
>      *  These are generic thread scheduling characteristics.
>      */
>     preempt_enabled = false;
> +#if !defined( RTEMS_SMP )
>     if ( mask & RTEMS_PREEMPT_MASK ) {
> -#if defined( RTEMS_SMP )
>       if ( rtems_configuration_is_smp_enabled() &&
>            !_Modes_Is_preempt( mode_set ) ) {
>         return RTEMS_NOT_IMPLEMENTED;
>       }
> -#endif
>       bool is_preempt_enabled = _Modes_Is_preempt( mode_set );
>   
>       preempt_enabled = !executing->is_preemptible && is_preempt_enabled;
>       executing->is_preemptible = is_preempt_enabled;
>     }
> +#endif
>   
>     if ( mask & RTEMS_TIMESLICE_MASK ) {
>       if ( _Modes_Is_timeslice(mode_set) ) {
> @@ -88,8 +115,10 @@ rtems_status_code rtems_task_mode(
>     /*
>      *  Set the new interrupt level
>      */
> +#if !defined( RTEMS_SMP )
>     if ( mask & RTEMS_INTERRUPT_MASK )
>       _Modes_Set_interrupt_level( mode_set );
> +#endif
>   
>     /*
>      *  This is specific to the RTEMS API

-- 
Sebastian Huber, embedded brains GmbH

Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone   : +49 89 189 47 41-16
Fax     : +49 89 189 47 41-09
E-Mail  : sebastian.huber at embedded-brains.de
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