Turn pthread_spinlock_t into a self-contained object. On uni-processor
configurations, interrupts are disabled in the lock/trylock operations
and the previous interrupt status is restored in the corresponding
unlock operations. On SMP configurations, a ticket lock is a acquired
and released in addition.
The self-contained pthread_spinlock_t object is defined by Newlib in
<sys/_pthreadtypes.h>.
typedef struct {
struct _Ticket_lock_Control _lock;
__uint32_t _interrupt_state;
} pthread_spinlock_t;
This implementation is simple and efficient. However, this test case of
the Linux Test Project would fail due to call of printf() and sleep()
during spin lock ownership:
https://github.com/linux-test-project/ltp/blob/master/testcases/open_posix_testsuite/conformance/interfaces/pthread_spin_lock/1-2.c
There is only limited support for profiling on SMP configurations.
Delete CORE spinlock implementation.
Update #2674.
Replace the expected thread dispatch disable level with a thread queue
enqueue callout. This enables the use of _Thread_Dispatch_direct() in
the thread queue enqueue procedure. This avoids impossible exection
paths, e.g. Per_CPU_Control::dispatch_necessary is always true.
On SMP configurations, it is a fatal error to call blocking operating
system with interrupts disabled, since this prevents delivery of
inter-processor interrupts. This could lead to executing threads which
are not allowed to execute resulting in undefined behaviour.
The ARM Cortex-M port has a similar problem, since the interrupt state
is not a part of the thread context.
Update #2811.
Avoid rtems_semaphore_flush() to reduce the maximum thread dispatch
disabled time of this test. Remove superfluous yield and malloc().
Ensure that no resource leak occurs.
We cannot use the MRS or MSR instructions in Thumb-1 mode. Stay in ARM
mode for the Thumb-1 targets during interrupt low-level processing.
Update #2751.
Use a processor-specific interrupt frame during context switches in case
the executing thread is longer executes on the processor and the heir
thread is about to start execution. During this period we must not use
a thread stack for interrupt processing.
Update #2809.
This function is useful for operations which synchronously block, e.g.
self restart, self deletion, yield, sleep. It helps to detect if these
operations are called in the wrong context. Since the thread dispatch
necessary indicator is not used, this is more robust in some SMP
situations.
Update #2751.
