From 709796209c88e6749320b3096df57f369c2d62be Mon Sep 17 00:00:00 2001
From: Sebastian Huber <sebastian.huber@embedded-brains.de>
Date: Wed, 29 Aug 2018 09:43:44 +0200
Subject: score: Add thread pin/unpin support

Add support to temporarily pin a thread to its current processor.  This
may be used to access per-processor data structures in critical sections
with enabled thread dispatching, e.g. a pinned thread is allowed to
block.

Update #3508.
---
 cpukit/include/rtems/score/threadimpl.h | 52 ++++++++++++++++++++++++++++++++-
 1 file changed, 51 insertions(+), 1 deletion(-)

(limited to 'cpukit/include/rtems/score/threadimpl.h')

diff --git a/cpukit/include/rtems/score/threadimpl.h b/cpukit/include/rtems/score/threadimpl.h
index 4ab855d3ff..530035ff67 100644
--- a/cpukit/include/rtems/score/threadimpl.h
+++ b/cpukit/include/rtems/score/threadimpl.h
@@ -1025,7 +1025,7 @@ RTEMS_INLINE_ROUTINE const Scheduler_Control *_Thread_Scheduler_get_home(
 )
 {
 #if defined(RTEMS_SMP)
-  return the_thread->Scheduler.home;
+  return the_thread->Scheduler.home_scheduler;
 #else
   (void) the_thread;
   return &_Scheduler_Table[ 0 ];
@@ -1953,6 +1953,56 @@ size_t _Thread_Get_name(
   size_t                buffer_size
 );
 
+#if defined(RTEMS_SMP)
+#define THREAD_PIN_STEP 2
+
+#define THREAD_PIN_PREEMPTION 1
+
+void _Thread_Do_unpin(
+  Thread_Control  *executing,
+  Per_CPU_Control *cpu_self
+);
+#endif
+
+RTEMS_INLINE_ROUTINE void _Thread_Pin( Thread_Control *executing )
+{
+#if defined(RTEMS_SMP)
+  _Assert( executing == _Thread_Executing );
+
+  executing->Scheduler.pin_level += THREAD_PIN_STEP;
+#else
+  (void) executing;
+#endif
+}
+
+RTEMS_INLINE_ROUTINE void _Thread_Unpin(
+  Thread_Control  *executing,
+  Per_CPU_Control *cpu_self
+)
+{
+#if defined(RTEMS_SMP)
+  unsigned int pin_level;
+
+  _Assert( executing == _Thread_Executing );
+
+  pin_level = executing->Scheduler.pin_level;
+  _Assert( pin_level > 0 );
+
+  if (
+    RTEMS_PREDICT_TRUE(
+      pin_level != ( THREAD_PIN_STEP | THREAD_PIN_PREEMPTION )
+    )
+  ) {
+    executing->Scheduler.pin_level = pin_level - THREAD_PIN_STEP;
+  } else {
+    _Thread_Do_unpin( executing, cpu_self );
+  }
+#else
+  (void) executing;
+  (void) cpu_self;
+#endif
+}
+
 /** @}*/
 
 #ifdef __cplusplus
-- 
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