Remove the thread action handler parameter from
_Thread_Action_initialize() and instead set it later in
_Thread_Add_post_switch_action(). This avoids a dependency on the
thread action handler via the thread initialization.
Move the storage for the thread queue heads to the threads. Each thread
provides a set of thread queue heads allocated from a dedicated memory
pool. In case a thread blocks on a queue, then it lends its heads to
the queue. In case the thread unblocks, then it takes a free set of
threads from the queue. Since a thread can block on at most one queue
this works. This mechanism is used in FreeBSD. The motivation for this
change is to reduce the memory demands of the synchronization objects.
On a 32-bit uni-processor configuration the Thread_queue_Control size is
now 8 bytes, compared to 64 bytes in RTEMS 4.10 (other changes reduced
the size as well).
Separate the thread queue heads and lock from the operations. This
enables the support for light weight objects which only support one
queuing discipline.
Avoid Thread_Control typedef in <rtems/score/percpu.h>. This helps to
get rid of the <rtems/score/percpu.h> include in <rtems/score/thread.h>
which exposes a lot of implementation details.
Add an assert to ensure that the watchdog is the proper state for a
_Watchdog_Initialize(). This helps to detect invalid initializations
which may lead to a corrupt watchdog chain.
Store the floating-point unit property in the thread control block
regardless of the CPU_HARDWARE_FP and CPU_SOFTWARE_FP settings. Make
sure the floating-point unit is only enabled for the corresponding
multilibs. This helps targets which have a volatile only floating point
context like SPARC for example.
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.
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.
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.
Add watchdog header parameter to _Watchdog_Remove() to be in line with
the other operations. Add _Watchdog_Remove_ticks() and
_Watchdog_Remove_seconds() for convenience.
Update #2307.
Avoid the usage of the current thread state in
_Thread_queue_Extract_with_return_code() since thread queues should not
know anything about thread states.
A thread join is twofold. There is one thread that exists and an
arbitrary number of threads that wait for the thread exit (one-to-many
relation). The exiting thread may want to wait for a thread that wants
to join its exit (STATES_WAITING_FOR_JOIN_AT_EXIT in
_POSIX_Thread_Exit()). On the other side we need a thread queue for all
the threads that wait for the exit of one particular thread
(STATES_WAITING_FOR_JOIN in pthread_join()).
Update #2035.
Do not disable thread dispatching and do not acquire the Giant lock.
This makes it possible to use this object get variant for fine grained
locking.
Update #2273.
pthread_mutex_trylock() should return EBUSY if the mutex is already
locked. The translations of CORE_MUTEX_STATUS_NESTING_NOT_ALLOWED is
EDEADLK which is correct for pthread_mutex_lock(). This fixes the
translation for trylock.
Closes#2170.
