[PATCH v2 2/2] c-user: Document new rtems_task_delete() behaviour

Chris Johns chrisj at rtems.org
Thu Jul 28 00:08:01 UTC 2022



On 27/7/2022 7:30 pm, Sebastian Huber wrote:
> Update #4679.
> ---
>  c-user/task/directives.rst | 25 ++++++++++++++++++++-----
>  1 file changed, 20 insertions(+), 5 deletions(-)
> diff --git a/c-user/task/directives.rst b/c-user/task/directives.rst
> index 64b591d..b78aaa9 100644
> --- a/c-user/task/directives.rst
> +++ b/c-user/task/directives.rst
> @@ -805,14 +805,26 @@ specified by ``id``.
>      The directive was called from within interrupt context.
> +    The task termination procedure was started, however, waiting for the
> +    terminating task would have resulted in a deadlock.
> +
>      The task resided on a remote node.
>  .. rubric:: NOTES:
> -RTEMS stops the execution of the task and reclaims the stack memory, any
> -allocated delay or timeout timers, the TCB, and, if the task is
> -:c:macro:`RTEMS_FLOATING_POINT`, its floating point context area. RTEMS
> +The task deletion is done in several steps.  Firstly, the task is marked as
> +terminating.  While the task life of the terminating task is protected, it
> +executes normally until it disables the task life protection or it deletes
> +itself.  A terminating task will eventually stop its normal execution and start
> +its termination procedure.  The procedure executes in the context of the
> +terminating task.  The task termination procedure involves the destruction of
> +POSIX key values and running the task termination user extensions.  Once
> +complete the execution of the task is stopped and task-specific resources are
> +reclaimed by the system, such as the stack memory, any allocated delay or
> +timeout timers, the :term:`TCB`, and, if the task is
> +:c:macro:`RTEMS_FLOATING_POINT`, its floating point context area.  RTEMS
>  explicitly does not reclaim the following resources: region segments, partition
>  buffers, semaphores, timers, or rate monotonic periods.
> @@ -824,10 +836,13 @@ resources before deletion.  A task can be directed to release its resources and
>  delete itself by restarting it with a special argument or by sending it a
>  message, an event, or a signal.
> -Deletion of the current task (:c:macro:`RTEMS_SELF`) will force RTEMS to select
> +Deletion of the calling task (:c:macro:`RTEMS_SELF`) will force RTEMS to select
>  another task to execute.
> -The :term:`TCB` for the deleted task is reclaimed by RTEMS.
> +When a task deletes another task, the calling task waits until the task
> +termination procedure of the task being deleted has completed.  The terminating
> +task inherits the :term:`eligible priorities <eligible priority>` of the
> +calling task.
>  When a global task is deleted, the task identifier must be transmitted to every
>  node in the system for deletion from the local copy of the global object table.

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