From c654b52517c2d255aa98eed347edeba60dc854d0 Mon Sep 17 00:00:00 2001 From: Sebastian Huber Date: Thu, 30 Apr 2015 13:18:45 +0200 Subject: score: Delete _CORE_message_queue_Flush_support() Check the number of pending messages in _CORE_message_queue_Flush() to avoid race conditions. --- cpukit/score/Makefile.am | 2 +- cpukit/score/include/rtems/score/coremsgimpl.h | 17 ------ cpukit/score/src/coremsgclose.c | 3 +- cpukit/score/src/coremsgflush.c | 72 ++++++++++++++++++---- cpukit/score/src/coremsgflushsupp.c | 84 -------------------------- 5 files changed, 62 insertions(+), 116 deletions(-) delete mode 100644 cpukit/score/src/coremsgflushsupp.c diff --git a/cpukit/score/Makefile.am b/cpukit/score/Makefile.am index 19d3237607..6d4414c430 100644 --- a/cpukit/score/Makefile.am +++ b/cpukit/score/Makefile.am @@ -158,7 +158,7 @@ libscore_a_SOURCES += src/corebarrier.c src/corebarrierrelease.c \ ## CORE_MESSAGE_QUEUE_C_FILES libscore_a_SOURCES += src/coremsg.c src/coremsgbroadcast.c \ src/coremsgclose.c src/coremsgflush.c src/coremsgflushwait.c \ - src/coremsginsert.c src/coremsgflushsupp.c src/coremsgseize.c \ + src/coremsginsert.c src/coremsgseize.c \ src/coremsgsubmit.c ## CORE_MUTEX_C_FILES diff --git a/cpukit/score/include/rtems/score/coremsgimpl.h b/cpukit/score/include/rtems/score/coremsgimpl.h index cedf2760e8..1f6796905b 100644 --- a/cpukit/score/include/rtems/score/coremsgimpl.h +++ b/cpukit/score/include/rtems/score/coremsgimpl.h @@ -179,23 +179,6 @@ uint32_t _CORE_message_queue_Flush( CORE_message_queue_Control *the_message_queue ); -/** - * @brief Flush all outstanding messages. - * - * This routine flushes all outstanding messages and returns - * them to the inactive message chain. - * - * @param[in] the_message_queue points to the message queue to flush - * - * @retval This method returns the number of pending messages flushed. - * - * - INTERRUPT LATENCY: - * + single case - */ -uint32_t _CORE_message_queue_Flush_support( - CORE_message_queue_Control *the_message_queue -); - #if defined(FUNCTIONALITY_NOT_CURRENTLY_USED_BY_ANY_API) /** * @brief Flush waiting threads. diff --git a/cpukit/score/src/coremsgclose.c b/cpukit/score/src/coremsgclose.c index 17ecc4428e..d808a4efbc 100644 --- a/cpukit/score/src/coremsgclose.c +++ b/cpukit/score/src/coremsgclose.c @@ -49,8 +49,7 @@ void _CORE_message_queue_Close( * the flush satisfying any blocked senders as a side-effect. */ - if ( the_message_queue->number_of_pending_messages != 0 ) - (void) _CORE_message_queue_Flush_support( the_message_queue ); + (void) _CORE_message_queue_Flush( the_message_queue ); (void) _Workspace_Free( the_message_queue->message_buffers ); diff --git a/cpukit/score/src/coremsgflush.c b/cpukit/score/src/coremsgflush.c index 51f6c8db98..05683f0327 100644 --- a/cpukit/score/src/coremsgflush.c +++ b/cpukit/score/src/coremsgflush.c @@ -1,8 +1,9 @@ /** - * @file + * @file * - * @brief Flush Pending Messages - * @ingroup ScoreMessageQueue + * @brief Flush Messages Routine + * + * @ingroup ScoreMessageQueue */ /* @@ -18,19 +19,66 @@ #include "config.h" #endif -#include -#include -#include #include -#include -#include +#include uint32_t _CORE_message_queue_Flush( CORE_message_queue_Control *the_message_queue ) { - if ( the_message_queue->number_of_pending_messages != 0 ) - return _CORE_message_queue_Flush_support( the_message_queue ); - else - return 0; + ISR_Level level; + Chain_Node *inactive_head; + Chain_Node *inactive_first; + Chain_Node *message_queue_first; + Chain_Node *message_queue_last; + uint32_t count; + + /* + * Currently, RTEMS supports no API that has both flush and blocking + * sends. Thus, this routine assumes that there are no senders + * blocked waiting to send messages. In the event, that an API is + * added that can flush a message queue when threads are blocked + * waiting to send, there are two basic behaviors envisioned: + * + * (1) The thread queue of pending senders is a logical extension + * of the pending message queue. In this case, it should be + * flushed using the _Thread_queue_Flush() service with a status + * such as CORE_MESSAGE_QUEUE_SENDER_FLUSHED (which currently does + * not exist). This can be implemented without changing the "big-O" + * of the message flushing part of the routine. + * + * (2) Only the actual messages queued should be purged. In this case, + * the blocked sender threads must be allowed to send their messages. + * In this case, the implementation will be forced to individually + * dequeue the senders and queue their messages. This will force + * this routine to have "big O(n)" where n is the number of blocked + * senders. If there are more messages pending than senders blocked, + * then the existing flush code can be used to dispose of the remaining + * pending messages. + * + * For now, though, we are very happy to have a small routine with + * fixed execution time that only deals with pending messages. + */ + + _ISR_Disable( level ); + + count = the_message_queue->number_of_pending_messages; + if ( count != 0 ) { + the_message_queue->number_of_pending_messages = 0; + + inactive_head = _Chain_Head( &the_message_queue->Inactive_messages ); + inactive_first = inactive_head->next; + message_queue_first = _Chain_First( &the_message_queue->Pending_messages ); + message_queue_last = _Chain_Last( &the_message_queue->Pending_messages ); + + inactive_head->next = message_queue_first; + message_queue_last->next = inactive_first; + inactive_first->previous = message_queue_last; + message_queue_first->previous = inactive_head; + + _Chain_Initialize_empty( &the_message_queue->Pending_messages ); + } + + _ISR_Enable( level ); + return count; } diff --git a/cpukit/score/src/coremsgflushsupp.c b/cpukit/score/src/coremsgflushsupp.c deleted file mode 100644 index 041972fb9c..0000000000 --- a/cpukit/score/src/coremsgflushsupp.c +++ /dev/null @@ -1,84 +0,0 @@ -/** - * @file - * - * @brief Flush Messages Support Routine - * - * @ingroup ScoreMessageQueue - */ - -/* - * COPYRIGHT (c) 1989-1999. - * On-Line Applications Research Corporation (OAR). - * - * 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 -#include -#include -#include -#include -#include - -uint32_t _CORE_message_queue_Flush_support( - CORE_message_queue_Control *the_message_queue -) -{ - ISR_Level level; - Chain_Node *inactive_head; - Chain_Node *inactive_first; - Chain_Node *message_queue_first; - Chain_Node *message_queue_last; - uint32_t count; - - /* - * Currently, RTEMS supports no API that has both flush and blocking - * sends. Thus, this routine assumes that there are no senders - * blocked waiting to send messages. In the event, that an API is - * added that can flush a message queue when threads are blocked - * waiting to send, there are two basic behaviors envisioned: - * - * (1) The thread queue of pending senders is a logical extension - * of the pending message queue. In this case, it should be - * flushed using the _Thread_queue_Flush() service with a status - * such as CORE_MESSAGE_QUEUE_SENDER_FLUSHED (which currently does - * not exist). This can be implemented without changing the "big-O" - * of the message flushing part of the routine. - * - * (2) Only the actual messages queued should be purged. In this case, - * the blocked sender threads must be allowed to send their messages. - * In this case, the implementation will be forced to individually - * dequeue the senders and queue their messages. This will force - * this routine to have "big O(n)" where n is the number of blocked - * senders. If there are more messages pending than senders blocked, - * then the existing flush code can be used to dispose of the remaining - * pending messages. - * - * For now, though, we are very happy to have a small routine with - * fixed execution time that only deals with pending messages. - */ - - _ISR_Disable( level ); - inactive_head = _Chain_Head( &the_message_queue->Inactive_messages ); - inactive_first = inactive_head->next; - message_queue_first = _Chain_First( &the_message_queue->Pending_messages ); - message_queue_last = _Chain_Last( &the_message_queue->Pending_messages ); - - inactive_head->next = message_queue_first; - message_queue_last->next = inactive_first; - inactive_first->previous = message_queue_last; - message_queue_first->previous = inactive_head; - - _Chain_Initialize_empty( &the_message_queue->Pending_messages ); - - count = the_message_queue->number_of_pending_messages; - the_message_queue->number_of_pending_messages = 0; - _ISR_Enable( level ); - return count; -} -- cgit v1.2.3