[rtems commit] smp: Fix _Thread_Dispatch_decrement_disable_level

[Sebastian Huber]

Module:    rtems
Branch:    master
Commit:    aabfcd0c3330830356a55782e2bdc99e3979165a
Changeset: http://git.rtems.org/rtems/commit/?id=aabfcd0c3330830356a55782e2bdc99e3979165a

Author:    Sebastian Huber <sebastian.huber at embedded-brains.de>
Date:      Wed Jun 12 15:11:57 2013 +0200

smp: Fix _Thread_Dispatch_decrement_disable_level

We must obtain the processor ID after interrupts are disabled since a
non-optimizing compiler may store the value on the stack and read it
back.

---

 cpukit/score/src/threaddispatchdisablelevel.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/cpukit/score/src/threaddispatchdisablelevel.c b/cpukit/score/src/threaddispatchdisablelevel.c
index 4686795..154a6af 100644
--- a/cpukit/score/src/threaddispatchdisablelevel.c
+++ b/cpukit/score/src/threaddispatchdisablelevel.c
@@ -56,12 +56,18 @@ uint32_t _Thread_Dispatch_increment_disable_level( void )
 {
   Thread_Dispatch_disable_level_lock_control *level_lock =
     &_Thread_Dispatch_disable_level_lock;
-  int self_cpu = bsp_smp_processor_id();
+  int self_cpu;
   ISR_Level isr_level;
   uint32_t disable_level;
 
   _ISR_Disable_on_this_core( isr_level );
 
+  /*
+   * We must obtain the processor ID after interrupts are disabled since a
+   * non-optimizing compiler may store the value on the stack and read it back.
+   */
+  self_cpu = bsp_smp_processor_id();
+
   if ( level_lock->owner_cpu != self_cpu ) {
     _SMP_lock_Acquire( &level_lock->lock );
     level_lock->owner_cpu = self_cpu;