Changeset 91e7b0c in rtems

score: PR2172: _Thread_queue_Extract()

Add _Thread_queue_Extract_with_return_code(). On SMP this sequence in
_Thread_queue_Process_timeout() was broken:

[...]

/*

• After we enable interrupts here, a lot may happen in the
• meantime, e.g. nested interrupts may release the resource that
• times out here. So we enter _Thread_queue_Extract()
• speculatively. Inside this function we check the actual status
• under ISR disable protection. This ensures that exactly one
• executing context performs the extract operation (other parties
• may call _Thread_queue_Dequeue()). If this context won, then
• we have a timeout. *
• We can use the_thread_queue pointer here even if
• the_thread->Wait.queue is already set to NULL since the extract
• operation will only use the thread queue discipline to select
• the right extract operation. The timeout status is set during
• thread queue initialization. */

we_did_it = _Thread_queue_Extract( the_thread_queue, the_thread );
if ( we_did_it ) {

the_thread->Wait.return_code = the_thread_queue->timeout_status;

}

[...]

In case _Thread_queue_Extract() successfully extracted a thread, then
this thread may start execution on a remote processor immediately and
read the the_thread->Wait.return_code before we update it here with the
timeout status. Thus it observes a successful operation even if it
timed out.