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authorSebastian Huber <sebastian.huber@embedded-brains.de>2014-06-12 14:37:57 +0200
committerSebastian Huber <sebastian.huber@embedded-brains.de>2014-06-12 16:13:26 +0200
commit701dd96f598bd58a41884795ba5bf0b5da337d78 (patch)
tree2d8374400a2622c19ad5215e0d1e150eebda1396
parent970aa80fe19c9b476f728cd56e279191e3a40b23 (diff)
downloadrtems-701dd96f598bd58a41884795ba5bf0b5da337d78.tar.bz2
score: PR2181: Add _Thread_Yield()
The _Scheduler_Yield() was called by the executing thread with thread dispatching disabled and interrupts enabled. The rtems_task_suspend() is explicitly allowed in ISRs: http://rtems.org/onlinedocs/doc-current/share/rtems/html/c_user/Interrupt-Manager-Directives-Allowed-from-an-ISR.html#Interrupt-Manager-Directives-Allowed-from-an-ISR Unlike the other scheduler operations the locking was performed inside the operation. This lead to the following race condition. Suppose a ISR suspends the executing thread right before the yield scheduler operation. Now the executing thread is not longer in the set of ready threads. The typical scheduler operations did not check the thread state and will now extract the thread again and enqueue it. This corrupted data structures. Add _Thread_Yield() and do the scheduler yield operation with interrupts disabled. This has a negligible effect on the interrupt latency.
-rw-r--r--cpukit/posix/src/nanosleep.c3
-rw-r--r--cpukit/posix/src/sched_yield.c7
-rw-r--r--cpukit/rtems/src/taskwakeafter.c3
-rw-r--r--cpukit/score/Makefile.am1
-rw-r--r--cpukit/score/include/rtems/score/schedulersmpimpl.h21
-rw-r--r--cpukit/score/include/rtems/score/threadimpl.h2
-rw-r--r--cpukit/score/src/schedulerdefaulttick.c4
-rw-r--r--cpukit/score/src/scheduleredfyield.c7
-rw-r--r--cpukit/score/src/schedulerprioritysmp.c14
-rw-r--r--cpukit/score/src/schedulerpriorityyield.c23
-rw-r--r--cpukit/score/src/schedulersimplesmp.c14
-rw-r--r--cpukit/score/src/schedulersimpleyield.c15
-rw-r--r--cpukit/score/src/threadyield.c41
13 files changed, 98 insertions, 57 deletions
diff --git a/cpukit/posix/src/nanosleep.c b/cpukit/posix/src/nanosleep.c
index ebaef33b26..54902b9c75 100644
--- a/cpukit/posix/src/nanosleep.c
+++ b/cpukit/posix/src/nanosleep.c
@@ -22,7 +22,6 @@
#include <errno.h>
#include <rtems/seterr.h>
-#include <rtems/score/schedulerimpl.h>
#include <rtems/score/threadimpl.h>
#include <rtems/score/timespec.h>
#include <rtems/score/watchdogimpl.h>
@@ -65,7 +64,7 @@ int nanosleep(
if ( !ticks ) {
_Thread_Disable_dispatch();
executing = _Thread_Executing;
- _Scheduler_Yield( _Scheduler_Get( executing ), executing );
+ _Thread_Yield( executing );
_Thread_Enable_dispatch();
if ( rmtp ) {
rmtp->tv_sec = 0;
diff --git a/cpukit/posix/src/sched_yield.c b/cpukit/posix/src/sched_yield.c
index 5293b199dc..e398fbf06e 100644
--- a/cpukit/posix/src/sched_yield.c
+++ b/cpukit/posix/src/sched_yield.c
@@ -21,16 +21,13 @@
#include <sched.h>
#include <rtems/score/percpu.h>
-#include <rtems/score/schedulerimpl.h>
#include <rtems/score/threaddispatch.h>
+#include <rtems/score/threadimpl.h>
int sched_yield( void )
{
- Thread_Control *executing;
-
_Thread_Disable_dispatch();
- executing = _Thread_Executing;
- _Scheduler_Yield( _Scheduler_Get( executing ), executing );
+ _Thread_Yield( _Thread_Executing );
_Thread_Enable_dispatch();
return 0;
}
diff --git a/cpukit/rtems/src/taskwakeafter.c b/cpukit/rtems/src/taskwakeafter.c
index 367b43acc6..88de6e51a8 100644
--- a/cpukit/rtems/src/taskwakeafter.c
+++ b/cpukit/rtems/src/taskwakeafter.c
@@ -20,7 +20,6 @@
#include <rtems/rtems/tasks.h>
#include <rtems/score/threadimpl.h>
-#include <rtems/score/schedulerimpl.h>
#include <rtems/score/watchdogimpl.h>
rtems_status_code rtems_task_wake_after(
@@ -37,7 +36,7 @@ rtems_status_code rtems_task_wake_after(
executing = _Thread_Executing;
if ( ticks == 0 ) {
- _Scheduler_Yield( _Scheduler_Get( executing ), executing );
+ _Thread_Yield( executing );
} else {
_Thread_Set_state( executing, STATES_DELAYING );
_Watchdog_Initialize(
diff --git a/cpukit/score/Makefile.am b/cpukit/score/Makefile.am
index 2fc31c574d..6caefb5f10 100644
--- a/cpukit/score/Makefile.am
+++ b/cpukit/score/Makefile.am
@@ -287,6 +287,7 @@ libscore_a_SOURCES += src/thread.c src/threadchangepriority.c \
src/threadstackallocate.c src/threadstackfree.c src/threadstart.c \
src/threadstartmultitasking.c src/iterateoverthreads.c \
src/threadblockingoperationcancel.c
+libscore_a_SOURCES += src/threadyield.c
if HAS_SMP
libscore_a_SOURCES += src/smpbarrierwait.c
diff --git a/cpukit/score/include/rtems/score/schedulersmpimpl.h b/cpukit/score/include/rtems/score/schedulersmpimpl.h
index b4126b5d6d..9d74434024 100644
--- a/cpukit/score/include/rtems/score/schedulersmpimpl.h
+++ b/cpukit/score/include/rtems/score/schedulersmpimpl.h
@@ -672,6 +672,27 @@ static inline void _Scheduler_SMP_Change_priority(
}
}
+static inline void _Scheduler_SMP_Yield(
+ Scheduler_Context *context,
+ Thread_Control *thread,
+ Scheduler_SMP_Extract extract_from_ready,
+ Scheduler_SMP_Enqueue enqueue_fifo,
+ Scheduler_SMP_Enqueue enqueue_scheduled_fifo
+)
+{
+ Scheduler_SMP_Node *node = _Scheduler_SMP_Node_get( thread );
+
+ if ( node->state == SCHEDULER_SMP_NODE_SCHEDULED ) {
+ _Scheduler_SMP_Extract_from_scheduled( thread );
+
+ ( *enqueue_scheduled_fifo )( context, thread );
+ } else {
+ ( *extract_from_ready )( context, thread );
+
+ ( *enqueue_fifo )( context, thread );
+ }
+}
+
static inline void _Scheduler_SMP_Insert_scheduled_lifo(
Scheduler_Context *context,
Thread_Control *thread
diff --git a/cpukit/score/include/rtems/score/threadimpl.h b/cpukit/score/include/rtems/score/threadimpl.h
index 7e6681bb75..e90346c75f 100644
--- a/cpukit/score/include/rtems/score/threadimpl.h
+++ b/cpukit/score/include/rtems/score/threadimpl.h
@@ -186,6 +186,8 @@ bool _Thread_Restart(
Thread_Entry_numeric_type numeric_argument
);
+void _Thread_Yield( Thread_Control *executing );
+
bool _Thread_Set_life_protection( bool protect );
void _Thread_Life_action_handler(
diff --git a/cpukit/score/src/schedulerdefaulttick.c b/cpukit/score/src/schedulerdefaulttick.c
index 98cd05e1c0..db67ca1508 100644
--- a/cpukit/score/src/schedulerdefaulttick.c
+++ b/cpukit/score/src/schedulerdefaulttick.c
@@ -29,6 +29,8 @@ void _Scheduler_default_Tick(
Thread_Control *executing
)
{
+ (void) scheduler;
+
#ifdef __RTEMS_USE_TICKS_FOR_STATISTICS__
/*
* Increment the number of ticks this thread has been executing
@@ -69,7 +71,7 @@ void _Scheduler_default_Tick(
* currently executing thread is placed at the rear of the
* FIFO for this priority and a new heir is selected.
*/
- _Scheduler_Yield( scheduler, executing );
+ _Thread_Yield( executing );
executing->cpu_time_budget =
rtems_configuration_get_ticks_per_timeslice();
}
diff --git a/cpukit/score/src/scheduleredfyield.c b/cpukit/score/src/scheduleredfyield.c
index 9eb07825fe..d43448becf 100644
--- a/cpukit/score/src/scheduleredfyield.c
+++ b/cpukit/score/src/scheduleredfyield.c
@@ -29,9 +29,6 @@ void _Scheduler_EDF_Yield(
Scheduler_EDF_Context *context =
_Scheduler_EDF_Get_context( scheduler );
Scheduler_EDF_Node *node = _Scheduler_EDF_Node_get( the_thread );
- ISR_Level level;
-
- _ISR_Disable( level );
/*
* The RBTree has more than one node, enqueue behind the tasks
@@ -40,9 +37,5 @@ void _Scheduler_EDF_Yield(
_RBTree_Extract( &context->Ready, &node->Node );
_RBTree_Insert( &context->Ready, &node->Node );
- _ISR_Flash( level );
-
_Scheduler_EDF_Schedule_body( scheduler, the_thread, false );
-
- _ISR_Enable( level );
}
diff --git a/cpukit/score/src/schedulerprioritysmp.c b/cpukit/score/src/schedulerprioritysmp.c
index 96b1689f37..bcbd26df3f 100644
--- a/cpukit/score/src/schedulerprioritysmp.c
+++ b/cpukit/score/src/schedulerprioritysmp.c
@@ -237,12 +237,12 @@ void _Scheduler_priority_SMP_Yield(
)
{
Scheduler_Context *context = _Scheduler_Get_context( scheduler );
- ISR_Level level;
- _ISR_Disable( level );
-
- _Scheduler_SMP_Extract_from_scheduled( thread );
- _Scheduler_priority_SMP_Enqueue_scheduled_fifo( context, thread );
-
- _ISR_Enable( level );
+ return _Scheduler_SMP_Yield(
+ context,
+ thread,
+ _Scheduler_priority_SMP_Extract_from_ready,
+ _Scheduler_priority_SMP_Enqueue_fifo,
+ _Scheduler_priority_SMP_Enqueue_scheduled_fifo
+ );
}
diff --git a/cpukit/score/src/schedulerpriorityyield.c b/cpukit/score/src/schedulerpriorityyield.c
index f2aeada660..60bab3983e 100644
--- a/cpukit/score/src/schedulerpriorityyield.c
+++ b/cpukit/score/src/schedulerpriorityyield.c
@@ -19,7 +19,6 @@
#endif
#include <rtems/score/schedulerpriorityimpl.h>
-#include <rtems/score/isr.h>
#include <rtems/score/threadimpl.h>
void _Scheduler_priority_Yield(
@@ -29,23 +28,19 @@ void _Scheduler_priority_Yield(
{
Scheduler_priority_Node *node = _Scheduler_priority_Node_get( the_thread );
Chain_Control *ready_chain = node->Ready_queue.ready_chain;
- ISR_Level level;
(void) scheduler;
- _ISR_Disable( level );
- if ( !_Chain_Has_only_one_node( ready_chain ) ) {
- _Chain_Extract_unprotected( &the_thread->Object.Node );
- _Chain_Append_unprotected( ready_chain, &the_thread->Object.Node );
+ if ( !_Chain_Has_only_one_node( ready_chain ) ) {
+ _Chain_Extract_unprotected( &the_thread->Object.Node );
+ _Chain_Append_unprotected( ready_chain, &the_thread->Object.Node );
- _ISR_Flash( level );
-
- if ( _Thread_Is_heir( the_thread ) )
- _Thread_Heir = (Thread_Control *) _Chain_First( ready_chain );
- _Thread_Dispatch_necessary = true;
+ if ( _Thread_Is_heir( the_thread ) ) {
+ _Thread_Heir = (Thread_Control *) _Chain_First( ready_chain );
}
- else if ( !_Thread_Is_heir( the_thread ) )
- _Thread_Dispatch_necessary = true;
- _ISR_Enable( level );
+ _Thread_Dispatch_necessary = true;
+ } else if ( !_Thread_Is_heir( the_thread ) ) {
+ _Thread_Dispatch_necessary = true;
+ }
}
diff --git a/cpukit/score/src/schedulersimplesmp.c b/cpukit/score/src/schedulersimplesmp.c
index eb260efd09..37458d6b6f 100644
--- a/cpukit/score/src/schedulersimplesmp.c
+++ b/cpukit/score/src/schedulersimplesmp.c
@@ -302,12 +302,12 @@ void _Scheduler_simple_SMP_Yield(
)
{
Scheduler_Context *context = _Scheduler_Get_context( scheduler );
- ISR_Level level;
- _ISR_Disable( level );
-
- _Scheduler_SMP_Extract_from_scheduled( thread );
- _Scheduler_simple_SMP_Enqueue_scheduled_fifo( context, thread );
-
- _ISR_Enable( level );
+ return _Scheduler_SMP_Yield(
+ context,
+ thread,
+ _Scheduler_simple_SMP_Extract_from_ready,
+ _Scheduler_simple_SMP_Enqueue_fifo,
+ _Scheduler_simple_SMP_Enqueue_scheduled_fifo
+ );
}
diff --git a/cpukit/score/src/schedulersimpleyield.c b/cpukit/score/src/schedulersimpleyield.c
index 65578d0bbb..b807530600 100644
--- a/cpukit/score/src/schedulersimpleyield.c
+++ b/cpukit/score/src/schedulersimpleyield.c
@@ -19,7 +19,6 @@
#endif
#include <rtems/score/schedulersimpleimpl.h>
-#include <rtems/score/isr.h>
void _Scheduler_simple_Yield(
const Scheduler_Control *scheduler,
@@ -28,16 +27,8 @@ void _Scheduler_simple_Yield(
{
Scheduler_simple_Context *context =
_Scheduler_simple_Get_context( scheduler );
- ISR_Level level;
- _ISR_Disable( level );
-
- _Chain_Extract_unprotected( &the_thread->Object.Node );
- _Scheduler_simple_Insert_priority_fifo( &context->Ready, the_thread );
-
- _ISR_Flash( level );
-
- _Scheduler_simple_Schedule_body( scheduler, the_thread, false );
-
- _ISR_Enable( level );
+ _Chain_Extract_unprotected( &the_thread->Object.Node );
+ _Scheduler_simple_Insert_priority_fifo( &context->Ready, the_thread );
+ _Scheduler_simple_Schedule_body( scheduler, the_thread, false );
}
diff --git a/cpukit/score/src/threadyield.c b/cpukit/score/src/threadyield.c
new file mode 100644
index 0000000000..b49e2b30ba
--- /dev/null
+++ b/cpukit/score/src/threadyield.c
@@ -0,0 +1,41 @@
+/**
+ * @file
+ *
+ * @brief Thread Yield
+ *
+ * @ingroup ScoreThread
+ */
+
+/*
+ * Copyright (c) 2014 embedded brains GmbH. All rights reserved.
+ *
+ * embedded brains GmbH
+ * Dornierstr. 4
+ * 82178 Puchheim
+ * Germany
+ * <rtems@embedded-brains.de>
+ *
+ * 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.
+ */
+
+#if HAVE_CONFIG_H
+ #include "config.h"
+#endif
+
+#include <rtems/score/threadimpl.h>
+#include <rtems/score/schedulerimpl.h>
+
+void _Thread_Yield( Thread_Control *executing )
+{
+ ISR_Level level;
+
+ _ISR_Disable( level );
+
+ if ( _States_Is_ready( executing->current_state ) ) {
+ _Scheduler_Yield( _Scheduler_Get( executing ), executing );
+ }
+
+ _ISR_Enable( level );
+}