Thread dispatching is disabled in case interrupts are disabled. To get
an accurate thread dispatch disabled time it is important to use the
interrupt disabled instant in case a transition from an interrupt
disabled section to a thread dispatch level section happens.
Move the writes to Thread_Control::current_priority and
Thread_Control::real_priority into _Thread_Change_priority() under the
protection of the thread lock. Add a filter function to
_Thread_Change_priority() to enable specialized variants.
Avoid race conditions during a thread priority restore with the new
Thread_Control::priority_restore_hint for an important average case
optimizations used by priority inheritance mutexes.
Update #2273.
Aggregate several critical sections into a bigger one. Sending and
receiving messages is now protected by an ISR lock. Thread dispatching
is only disabled in case a blocking operation is necessary. The message
copy procedure is done inside the critical section (interrupts
disabled). Thus this change may have a negative impact on the interrupt
latency in case very large messages are transferred.
Update #2273.
Use thread wait flags for synchronization. The enqueue operation is now
part of the initial critical section. This is the key change and
enables fine grained locking on SMP for objects using a thread queue
like semaphores and message queues.
Update #2273.
Move thread queue discipline specific operations into
Thread_queue_Operations. Use a separate node in the thread control
block for the thread queue to make it independent of the scheduler data
structures.
Update #2273.
Replace the Thread_Priority_control with more general
Thread_queue_Operations which will be used for generic priority change,
timeout, signal and wait queue operations in the future.
Update #2273.
Move the complete thread queue enqueue procedure into
_Thread_queue_Enqueue_critical(). It is possible to use the thread
queue lock to protect state of the object embedding the thread queue.
This enables per object fine grained locking in the future.
Delete _Thread_queue_Enter_critical_section().
Update #2273.
Merge THREAD_WAIT_STATE_SATISFIED, THREAD_WAIT_STATE_TIMEOUT,
THREAD_WAIT_STATE_INTERRUPT_SATISFIED, and
THREAD_WAIT_STATE_INTERRUPT_TIMEOUT into one state
THREAD_WAIT_STATE_READY_AGAIN. This helps to write generic routines to
block a thread.
Update #2273.
