posix: Add self-contained pthread spinlock

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.

1 files changed, 26 insertions, 10 deletions

diff --git a/cpukit/posix/src/pspinunlock.c b/cpukit/posix/src/pspinunlock.c
index b92473d7c1..b508df7384 100644
--- a/cpukit/posix/src/pspinunlock.c
+++ b/cpukit/posix/src/pspinunlock.c
@@ -11,6 +11,8 @@
  *  COPYRIGHT (c) 1989-2007.
  *  On-Line Applications Research Corporation (OAR).
  *
+ *  Copyright (c) 2016 embedded brains GmbH
+ *
  *  The license and distribution terms for this file may be
  *  found in the file LICENSE in this distribution or at
  *  http://www.rtems.org/license/LICENSE.
@@ -21,19 +23,33 @@
 #endif
 
 #include <rtems/posix/spinlockimpl.h>
-#include <rtems/posix/posixapi.h>
 
-int pthread_spin_unlock( pthread_spinlock_t *spinlock )
+int pthread_spin_unlock( pthread_spinlock_t *lock )
 {
   POSIX_Spinlock_Control *the_spinlock;
-  ISR_lock_Context        lock_context;
-  Status_Control          status;
+  ISR_Level               level;
 
-  the_spinlock = _POSIX_Spinlock_Get( spinlock, &lock_context );
-  if ( the_spinlock == NULL ) {
-    return EINVAL;
+  the_spinlock = _POSIX_Spinlock_Get( lock );
+  level = the_spinlock->interrupt_state;
+#if defined(POSIX_SPINLOCKS_ARE_SELF_CONTAINED)
+#if defined(RTEMS_SMP)
+  _SMP_ticket_lock_Release(
+    &the_spinlock->Lock,
+    &_Per_CPU_Get()->Lock_stats_context
+  );
+#endif
+  _ISR_Local_enable( level );
+#else
+  if ( --_POSIX_Spinlock_Nest_level == 0 ) {
+#if defined(RTEMS_SMP)
+    _POSIX_Spinlock_Owner = 0xffffffff;
+    _SMP_ticket_lock_Release(
+      &the_spinlock->Lock,
+      &_Per_CPU_Get()->Lock_stats_context
+    );
+#endif
+    _ISR_Local_enable( level );
   }
-
-  status = _CORE_spinlock_Surrender( &the_spinlock->Spinlock, &lock_context );
-  return _POSIX_Get_error( status );
+#endif
+  return 0;
 }