[rtems commit] score: Critical section change in _Thread_Dispatch
Sebastian Huber
sebh at rtems.org
Tue Jul 30 07:48:50 UTC 2013
Module: rtems
Branch: master
Commit: 10b51ae7396192f311fe106fe870cdce62973f92
Changeset: http://git.rtems.org/rtems/commit/?id=10b51ae7396192f311fe106fe870cdce62973f92
Author: Sebastian Huber <sebastian.huber at embedded-brains.de>
Date: Fri Jul 26 15:46:04 2013 +0200
score: Critical section change in _Thread_Dispatch
If we enter _Thread_Dispatch() then _Thread_Dispatch_disable_level must
be zero. Single processor RTEMS assumes that stores of non-zero values
to _Thread_Dispatch_disable_level are observed by interrupts as non-zero values.
Move the _Thread_Dispatch_set_disable_level( 1 ) out of the first ISR
disabled critical section. In case interrupts happen between the
_Thread_Dispatch_set_disable_level( 1 ) and _ISR_Disable( level ) then
the interrupt will observe a non-zero _Thread_Dispatch_disable_level and
will not issue a _Thread_Dispatch() and we can enter the ISR disabled
section directly after interrupt processing.
This change leads to symmetry between the single processor and SMP
configuration.
---
cpukit/score/src/threaddispatch.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/cpukit/score/src/threaddispatch.c b/cpukit/score/src/threaddispatch.c
index b91eca8..ac906e4 100644
--- a/cpukit/score/src/threaddispatch.c
+++ b/cpukit/score/src/threaddispatch.c
@@ -70,6 +70,8 @@ void _Thread_Dispatch( void )
* If necessary, send dispatch request to other cores.
*/
_SMP_Request_other_cores_to_dispatch();
+ #else
+ _Thread_Dispatch_set_disable_level( 1 );
#endif
/*
@@ -82,8 +84,6 @@ void _Thread_Dispatch( void )
#if defined(RTEMS_SMP)
executing->is_executing = false;
heir->is_executing = true;
- #else
- _Thread_Dispatch_set_disable_level( 1 );
#endif
_Thread_Dispatch_necessary = false;
_Thread_Executing = heir;
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