[rtems commit] score: Simplify core barrier
Sebastian Huber
sebh at rtems.org
Wed Feb 24 09:47:56 UTC 2021
Module: rtems
Branch: master
Commit: 3cbdf19eacf45a8e9faad284b71775a9d56872dd
Changeset: http://git.rtems.org/rtems/commit/?id=3cbdf19eacf45a8e9faad284b71775a9d56872dd
Author: Sebastian Huber <sebastian.huber at embedded-brains.de>
Date: Sun Feb 21 10:21:26 2021 +0100
score: Simplify core barrier
Use the number of threads which must arrive at the barrier to trip the
automatic release also to indicate if the barrier is a manual release
barrier.
---
cpukit/include/rtems/score/corebarrier.h | 56 +++++++++-------------------
cpukit/include/rtems/score/corebarrierimpl.h | 56 +++++++---------------------
cpukit/rtems/src/barriercreate.c | 29 +++++++-------
cpukit/score/src/corebarrier.c | 7 ++--
cpukit/score/src/corebarrierwait.c | 17 +++++----
5 files changed, 59 insertions(+), 106 deletions(-)
diff --git a/cpukit/include/rtems/score/corebarrier.h b/cpukit/include/rtems/score/corebarrier.h
index 60abbd6..7cfaedd 100644
--- a/cpukit/include/rtems/score/corebarrier.h
+++ b/cpukit/include/rtems/score/corebarrier.h
@@ -40,50 +40,30 @@ extern "C" {
*/
/**
- * Flavors of barriers.
- */
-typedef enum {
- /** This specifies that the barrier will automatically release when
- * the user specified number of threads have arrived at the barrier.
- */
- CORE_BARRIER_AUTOMATIC_RELEASE,
- /** This specifies that the user will have to manually release the barrier
- * in order to release the waiting threads.
- */
- CORE_BARRIER_MANUAL_RELEASE
-} CORE_barrier_Disciplines;
-
-/**
- * The following defines the control block used to manage the
- * attributes of each barrier.
+ * @brief This control block is used to manage a barrier.
*/
typedef struct {
- /** This field indicates whether the barrier is automatic or manual.
+ /**
+ * @brief This member is used to manage the set of tasks which are
+ * blocked waiting for the barrier to be released.
*/
- CORE_barrier_Disciplines discipline;
- /** This element indicates the number of threads which must arrive at the
- * barrier to trip the automatic release.
- */
- uint32_t maximum_count;
-} CORE_barrier_Attributes;
+ Thread_queue_Control Wait_queue;
-/**
- * The following defines the control block used to manage each
- * barrier.
- */
-typedef struct {
- /** This field is the Waiting Queue used to manage the set of tasks
- * which are blocked waiting for the barrier to be released.
+ /**
+ * @brief This member contains the current number of thread waiting at the
+ * barrier to be released.
*/
- Thread_queue_Control Wait_queue;
- /** This element is the set of attributes which define this instance's
- * behavior.
+ uint32_t number_of_waiting_threads;
+
+ /**
+ * @brief This member indicates the number of threads which must arrive at
+ * the barrier to trip the automatic release.
+ *
+ * Use ::CORE_BARRIER_MANUAL_RELEASE_MAXIMUM_COUNT to indicate a manual
+ * release barrier.
*/
- CORE_barrier_Attributes Attributes;
- /** This element contains the current number of thread waiting for this
- * barrier to be released. */
- uint32_t number_of_waiting_threads;
-} CORE_barrier_Control;
+ uint32_t maximum_count;
+} CORE_barrier_Control;
/** @} */
diff --git a/cpukit/include/rtems/score/corebarrierimpl.h b/cpukit/include/rtems/score/corebarrierimpl.h
index 922eb5d..86a3e95 100644
--- a/cpukit/include/rtems/score/corebarrierimpl.h
+++ b/cpukit/include/rtems/score/corebarrierimpl.h
@@ -34,6 +34,12 @@ extern "C" {
*/
/**
+ * @brief This maximum thread count constant indicates that the barrier is a
+ * manual release barrier.
+ */
+#define CORE_BARRIER_MANUAL_RELEASE_MAXIMUM_COUNT 0
+
+/**
* @brief These thread queue operations are used for core barriers.
*
* They are a specialization of ::_Thread_queue_Operations_FIFO. The only
@@ -43,16 +49,18 @@ extern "C" {
extern const Thread_queue_Operations _CORE_barrier_Thread_queue_operations;
/**
- * @brief Initializes the core barrier.
+ * @brief Initializes the core barrier.
*
- * This routine initializes the barrier based on the parameters passed.
+ * @param[out] the_barrier is the barrier to initialize.
*
- * @param[out] the_barrier The barrier to initialize.
- * @param[out] the_barrier_attributes The attributes which define the behavior of this instance.
+ * @param maximum_count is the number of threads which must arrive at the
+ * barrier to trip the automatic release or
+ * ::CORE_BARRIER_MANUAL_RELEASE_MAXIMUM_COUNT to indicate a manual release
+ * barrier.
*/
void _CORE_barrier_Initialize(
- CORE_barrier_Control *the_barrier,
- CORE_barrier_Attributes *the_barrier_attributes
+ CORE_barrier_Control *the_barrier,
+ uint32_t maximum_count
);
/**
@@ -173,42 +181,6 @@ RTEMS_INLINE_ROUTINE void _CORE_barrier_Flush(
);
}
-/**
- * @brief Checks if the barrier is automatic.
- *
- * This function returns true if the automatic release attribute is
- * enabled in the @a attribute_set and false otherwise.
- *
- * @param the_attribute The attribute set to test.
- *
- * @retval true The automatic release attribute is enabled.
- * @retval false The automatic release attribute is not enabled.
- */
-RTEMS_INLINE_ROUTINE bool _CORE_barrier_Is_automatic(
- CORE_barrier_Attributes *the_attribute
-)
-{
- return
- (the_attribute->discipline == CORE_BARRIER_AUTOMATIC_RELEASE);
-}
-
-/**
- * @brief Returns the number of currently waiting threads.
- *
- * This routine returns the number of threads currently waiting at the barrier.
- *
- * @param[in] the_barrier The barrier to obtain the number of blocked
- * threads of.
- *
- * @return the current count of waiting threads of this barrier.
- */
-RTEMS_INLINE_ROUTINE uint32_t _CORE_barrier_Get_number_of_waiting_threads(
- CORE_barrier_Control *the_barrier
-)
-{
- return the_barrier->number_of_waiting_threads;
-}
-
/** @} */
#ifdef __cplusplus
diff --git a/cpukit/rtems/src/barriercreate.c b/cpukit/rtems/src/barriercreate.c
index 99d916d..80b10e1 100644
--- a/cpukit/rtems/src/barriercreate.c
+++ b/cpukit/rtems/src/barriercreate.c
@@ -34,34 +34,35 @@ rtems_status_code rtems_barrier_create(
rtems_id *id
)
{
- Barrier_Control *the_barrier;
- CORE_barrier_Attributes the_attributes;
+ Barrier_Control *the_barrier;
+ uint32_t maximum_count;
- if ( !rtems_is_name_valid( name ) )
+ if ( !rtems_is_name_valid( name ) ) {
return RTEMS_INVALID_NAME;
+ }
- if ( !id )
+ if ( id == NULL ) {
return RTEMS_INVALID_ADDRESS;
+ }
- /* Initialize core barrier attributes */
if ( _Attributes_Is_barrier_automatic( attribute_set ) ) {
- the_attributes.discipline = CORE_BARRIER_AUTOMATIC_RELEASE;
- if ( maximum_waiters == 0 )
+ if ( maximum_waiters == 0 ) {
return RTEMS_INVALID_NUMBER;
- } else
- the_attributes.discipline = CORE_BARRIER_MANUAL_RELEASE;
- the_attributes.maximum_count = maximum_waiters;
+ }
+
+ maximum_count = maximum_waiters;
+ } else {
+ maximum_count = CORE_BARRIER_MANUAL_RELEASE_MAXIMUM_COUNT;
+ }
the_barrier = _Barrier_Allocate();
- if ( !the_barrier ) {
+ if ( the_barrier == NULL ) {
_Objects_Allocator_unlock();
return RTEMS_TOO_MANY;
}
- the_barrier->attribute_set = attribute_set;
-
- _CORE_barrier_Initialize( &the_barrier->Barrier, &the_attributes );
+ _CORE_barrier_Initialize( &the_barrier->Barrier, maximum_count );
*id = _Objects_Open_u32( &_Barrier_Information, &the_barrier->Object, name );
_Objects_Allocator_unlock();
diff --git a/cpukit/score/src/corebarrier.c b/cpukit/score/src/corebarrier.c
index c9c9b04..edb37d7 100644
--- a/cpukit/score/src/corebarrier.c
+++ b/cpukit/score/src/corebarrier.c
@@ -23,13 +23,12 @@
#include <rtems/score/corebarrierimpl.h>
void _CORE_barrier_Initialize(
- CORE_barrier_Control *the_barrier,
- CORE_barrier_Attributes *the_barrier_attributes
+ CORE_barrier_Control *the_barrier,
+ uint32_t maximum_count
)
{
-
- the_barrier->Attributes = *the_barrier_attributes;
the_barrier->number_of_waiting_threads = 0;
+ the_barrier->maximum_count = maximum_count;
_Thread_queue_Object_initialize( &the_barrier->Wait_queue );
}
diff --git a/cpukit/score/src/corebarrierwait.c b/cpukit/score/src/corebarrierwait.c
index 197e0cf..078276b 100644
--- a/cpukit/score/src/corebarrierwait.c
+++ b/cpukit/score/src/corebarrierwait.c
@@ -61,21 +61,22 @@ Status_Control _CORE_barrier_Seize(
Thread_queue_Context *queue_context
)
{
- uint32_t number_of_waiting_threads;
+ uint32_t new_number_of_waiting_threads;
_CORE_barrier_Acquire_critical( the_barrier, queue_context );
- number_of_waiting_threads = the_barrier->number_of_waiting_threads;
- ++number_of_waiting_threads;
+ /*
+ * In theory, this calculation can overflow. If this happens, then about 4
+ * billion threads are accidentally released. Currently, the system limit
+ * for threads is a bit lower with three times OBJECTS_INDEX_MASK - 1.
+ */
+ new_number_of_waiting_threads = the_barrier->number_of_waiting_threads + 1;
- if (
- _CORE_barrier_Is_automatic( &the_barrier->Attributes )
- && number_of_waiting_threads == the_barrier->Attributes.maximum_count
- ) {
+ if ( new_number_of_waiting_threads == the_barrier->maximum_count ) {
_CORE_barrier_Surrender( the_barrier, queue_context );
return STATUS_BARRIER_AUTOMATICALLY_RELEASED;
} else {
- the_barrier->number_of_waiting_threads = number_of_waiting_threads;
+ the_barrier->number_of_waiting_threads = new_number_of_waiting_threads;
_Thread_queue_Context_set_thread_state(
queue_context,
STATES_WAITING_FOR_BARRIER
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