Do not supsend self while waiting for termination since the
rtems_task_delete() may take place while the rtems_task_suspend() waits
for the Giant lock preventing delivery of the inter-processor interrupt.
The result is a suspended and terminated thread (this is a valid state,
but leads in this case to a test failure).
The previous timeout handling was flawed. In case a waiting thread
helped out the owner could use the scheduler node indefinitely long.
Update the resource tree in _MRSP_Timeout() to avoid this issue.
Bug reported by Luca Bonato.
Ensure that scheduler nodes in the SCHEDULER_HELP_ACTIVE_OWNER or
SCHEDULER_HELP_ACTIVE_RIVAL helping state are always
SCHEDULER_SMP_NODE_READY or SCHEDULER_SMP_NODE_SCHEDULED to ensure the
MrsP protocol properties.
New test case for smptests/smpmrsp01.
Fix _Scheduler_Block_node() in case the node is in the
SCHEDULER_HELP_ACTIVE_RIVAL helping state. For example a
rtems_task_suspend() on a task waiting for a MrsP semaphore.
Fix _Scheduler_Unblock_node() in case the node is in the
SCHEDULER_SMP_NODE_READY state. For example a rtems_task_resume() on a
task owning or waiting for a MrsP semaphore.
Add basic support for the Multiprocessor Resource Sharing Protocol
(MrsP).
The Multiprocessor Resource Sharing Protocol (MrsP) is defined in A.
Burns and A.J. Wellings, A Schedulability Compatible Multiprocessor
Resource Sharing Protocol - MrsP, Proceedings of the 25th Euromicro
Conference on Real-Time Systems (ECRTS 2013), July 2013. It is a
generalization of the Priority Ceiling Protocol to SMP systems. Each
MrsP semaphore uses a ceiling priority per scheduler instance. These
ceiling priorities can be specified with rtems_semaphore_set_priority().
A task obtaining or owning a MrsP semaphore will execute with the
ceiling priority for its scheduler instance as specified by the MrsP
semaphore object. Tasks waiting to get ownership of a MrsP semaphore
will not relinquish the processor voluntarily. In case the owner of a
MrsP semaphore gets preempted it can ask all tasks waiting for this
semaphore to help out and temporarily borrow the right to execute on one
of their assigned processors.
The help out feature is not implemented with this patch.
