From 7336be9d78266adfb540170e5105caf8eb003d2f Mon Sep 17 00:00:00 2001
From: Sebastian Huber <sebastian.huber@embedded-brains.de>
Date: Tue, 18 Feb 2014 13:40:39 +0100
Subject: score: SMP initialization and shutdown changes

Rename _SMP_Request_other_cores_to_perform_first_context_switch() into
_SMP_Request_start_multitasking() since this requests now a multitasking
start on all configured and available processors.  The name corresponds
_Thread_Start_multitasking() and
_SMP_Start_multitasking_on_secondary_processor() actions issued in
response to this request.  Move in source file to right place.

Rename PER_CPU_STATE_READY_TO_BEGIN_MULTITASKING into
PER_CPU_STATE_READY_TO_START_MULTITASKING.

Rename PER_CPU_STATE_BEGIN_MULTITASKING into
PER_CPU_STATE_REQUEST_START_MULTITASKING.

Rename _SMP_Request_other_cores_to_shutdown() into
_SMP_Request_shutdown().

Add a per-CPU state lock to protect all changes.  This was necessary to
offer a controlled shutdown of the system (atomic read/writes alone are
not sufficient for this kind of synchronization).

Add documentation for Per_CPU_State.

Delete debug output.

New tests smptests/smpfatal01 and smptests/smpfatal02.
---
 cpukit/score/src/smp.c | 77 +++++++++++++++-----------------------------------
 1 file changed, 23 insertions(+), 54 deletions(-)

(limited to 'cpukit/score/src/smp.c')

diff --git a/cpukit/score/src/smp.c b/cpukit/score/src/smp.c
index 59036eb466..0f632236b7 100644
--- a/cpukit/score/src/smp.c
+++ b/cpukit/score/src/smp.c
@@ -24,10 +24,6 @@
 #include <rtems/score/threadimpl.h>
 #include <rtems/config.h>
 
-#if defined(RTEMS_DEBUG)
-  #include <rtems/bspIo.h>
-#endif
-
 void _SMP_Handler_initialize( void )
 {
   uint32_t max_cpus = rtems_configuration_get_maximum_processors();
@@ -47,21 +43,38 @@ void _SMP_Handler_initialize( void )
   _SMP_Processor_count = max_cpus;
 }
 
-void _SMP_Start_multitasking_on_secondary_processor( void )
+void _SMP_Request_start_multitasking( void )
 {
   Per_CPU_Control *self_cpu = _Per_CPU_Get();
+  uint32_t ncpus = _SMP_Get_processor_count();
+  uint32_t cpu;
+
+  _Per_CPU_State_change( self_cpu, PER_CPU_STATE_READY_TO_START_MULTITASKING );
 
-  #if defined(RTEMS_DEBUG)
-    printk( "Made it to %d -- ", _Per_CPU_Get_index( self_cpu ) );
-  #endif
+  for ( cpu = 0 ; cpu < ncpus ; ++cpu ) {
+    Per_CPU_Control *per_cpu = _Per_CPU_Get_by_index( cpu );
+
+    _Per_CPU_State_change( per_cpu, PER_CPU_STATE_REQUEST_START_MULTITASKING );
+  }
+}
 
-  _Per_CPU_Change_state( self_cpu, PER_CPU_STATE_READY_TO_BEGIN_MULTITASKING );
+void _SMP_Start_multitasking_on_secondary_processor( void )
+{
+  Per_CPU_Control *self_cpu = _Per_CPU_Get();
 
-  _Per_CPU_Wait_for_state( self_cpu, PER_CPU_STATE_BEGIN_MULTITASKING );
+  _Per_CPU_State_change( self_cpu, PER_CPU_STATE_READY_TO_START_MULTITASKING );
 
   _Thread_Start_multitasking();
 }
 
+void _SMP_Request_shutdown( void )
+{
+  uint32_t self = _SMP_Get_current_processor();
+  Per_CPU_Control *self_cpu = _Per_CPU_Get_by_index( self );
+
+  _Per_CPU_State_change( self_cpu, PER_CPU_STATE_SHUTDOWN );
+}
+
 void _SMP_Send_message( uint32_t cpu, uint32_t message )
 {
   Per_CPU_Control *per_cpu = _Per_CPU_Get_by_index( cpu );
@@ -88,47 +101,3 @@ void _SMP_Broadcast_message( uint32_t message )
     }
   }
 }
-
-void _SMP_Request_other_cores_to_perform_first_context_switch( void )
-{
-  uint32_t self = _SMP_Get_current_processor();
-  uint32_t ncpus = _SMP_Get_processor_count();
-  uint32_t cpu;
-
-  for ( cpu = 0 ; cpu < ncpus ; ++cpu ) {
-    Per_CPU_Control *per_cpu = _Per_CPU_Get_by_index( cpu );
-
-    if ( cpu != self ) {
-      _Per_CPU_Wait_for_state(
-        per_cpu,
-        PER_CPU_STATE_READY_TO_BEGIN_MULTITASKING
-      );
-
-      _Per_CPU_Change_state( per_cpu, PER_CPU_STATE_BEGIN_MULTITASKING );
-    }
-  }
-}
-
-void _SMP_Request_other_cores_to_shutdown( void )
-{
-  uint32_t self = _SMP_Get_current_processor();
-
-  /*
-   * Do not use _SMP_Get_processor_count() since this value might be not
-   * initialized yet.  For example due to a fatal error in the middle of
-   * _CPU_SMP_Initialize().
-   */
-  uint32_t ncpus = rtems_configuration_get_maximum_processors();
-
-  uint32_t cpu;
-
-  for ( cpu = 0 ; cpu < ncpus ; ++cpu ) {
-    if ( cpu != self ) {
-      const Per_CPU_Control *per_cpu = _Per_CPU_Get_by_index( cpu );
-
-      if ( per_cpu->state != PER_CPU_STATE_BEFORE_INITIALIZATION ) {
-        _SMP_Send_message( cpu, SMP_MESSAGE_SHUTDOWN );
-      }
-    }
-  }
-}
-- 
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