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https://github.com/eclipse-threadx/threadx.git
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33efad3fee
* Fixed race condition and message loss in Cortex-M GNU, AC6, and IAR ports (#516) - Added compiler memory barriers to BASEPRI management functions in tx_port.h. - Added architectural barriers (DSB/ISB) to scheduler return paths in tx_port.h and tx_thread_system_return.S to prevent fall-through before context switch. - These changes address spurious thread resumption and lost messages, especially when TX_NOT_INTERRUPTABLE is enabled. - These changes ensure that pending interrupts (specifically PendSV) are recognised before subsequent instructions are executed, following Kairalite's feedback and ARM architectural guidelines. Assisted-by: Gemini (Gemini 2.0 Flash) ----- * Added a comment in common/tx_queue_cleanup to document why the NI path omits revalidation guards - In `TX_NOT_INTERRUPTABLE` mode, the caller keeps interrupts disabled across the entire cleanup call, so the race window that makes the guards necessary in the interruptable path cannot occur. Add a comment explaining this, and noting that all paths that resume a suspended thread clear tx_thread_suspend_cleanup before calling _tx_thread_system_ni_resume, making double-cleanup impossible. This prevents future false-positive suggestions (e.g. from AI tools) to add redundant checks to the NI path. Relates to: eclipse-threadx/threadx#516 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
233 lines
11 KiB
C
233 lines
11 KiB
C
/***************************************************************************
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* Copyright (c) 2024 Microsoft Corporation
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* Copyright (c) 2026-present Eclipse ThreadX contributors
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*
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* This program and the accompanying materials are made available under the
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* terms of the MIT License which is available at
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* https://opensource.org/licenses/MIT.
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*
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* SPDX-License-Identifier: MIT
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**************************************************************************/
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/**************************************************************************/
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/**************************************************************************/
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/** */
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/** ThreadX Component */
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/** */
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/** Queue */
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/** */
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/**************************************************************************/
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/**************************************************************************/
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#define TX_SOURCE_CODE
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/* Include necessary system files. */
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#include "tx_api.h"
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#include "tx_thread.h"
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#include "tx_queue.h"
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/**************************************************************************/
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/* */
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/* FUNCTION RELEASE */
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/* */
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/* _tx_queue_cleanup PORTABLE C */
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/* 6.1 */
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/* AUTHOR */
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/* */
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/* William E. Lamie, Microsoft Corporation */
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/* */
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/* DESCRIPTION */
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/* */
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/* This function processes queue timeout and thread terminate */
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/* actions that require the queue data structures to be cleaned */
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/* up. */
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/* */
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/* INPUT */
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/* */
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/* thread_ptr Pointer to suspended thread's */
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/* control block */
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/* */
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/* OUTPUT */
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/* */
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/* None */
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/* */
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/* CALLS */
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/* */
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/* _tx_thread_system_resume Resume thread service */
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/* _tx_thread_system_ni_resume Non-interruptable resume thread */
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/* */
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/* CALLED BY */
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/* */
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/* _tx_thread_timeout Thread timeout processing */
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/* _tx_thread_terminate Thread terminate processing */
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/* _tx_thread_wait_abort Thread wait abort processing */
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/* */
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/**************************************************************************/
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VOID _tx_queue_cleanup(TX_THREAD *thread_ptr, ULONG suspension_sequence)
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{
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#ifndef TX_NOT_INTERRUPTABLE
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TX_INTERRUPT_SAVE_AREA
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#endif
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TX_QUEUE *queue_ptr;
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UINT suspended_count;
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TX_THREAD *next_thread;
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TX_THREAD *previous_thread;
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#ifndef TX_NOT_INTERRUPTABLE
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/* Disable interrupts to remove the suspended thread from the queue. */
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TX_DISABLE
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/* Determine if the cleanup is still required. */
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if (thread_ptr -> tx_thread_suspend_cleanup == &(_tx_queue_cleanup))
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{
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/* Check for valid suspension sequence. */
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if (suspension_sequence == thread_ptr -> tx_thread_suspension_sequence)
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{
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/* Setup pointer to queue control block. */
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queue_ptr = TX_VOID_TO_QUEUE_POINTER_CONVERT(thread_ptr -> tx_thread_suspend_control_block);
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/* Check for NULL queue pointer. */
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if (queue_ptr != TX_NULL)
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{
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/* Is the queue ID valid? */
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if (queue_ptr -> tx_queue_id == TX_QUEUE_ID)
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{
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/* Determine if there are any thread suspensions. */
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if (queue_ptr -> tx_queue_suspended_count != TX_NO_SUSPENSIONS)
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{
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#else
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/* TX_NOT_INTERRUPTABLE path: the revalidation guards present in the
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interruptable path above (cleanup pointer, suspension sequence, NULL
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queue pointer, queue ID, and suspended count checks) are intentionally
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omitted here. Those guards exist to handle the race window that opens
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when the interruptable path calls TX_RESTORE before invoking cleanup,
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allowing another context to service or abort the suspension in between.
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In TX_NOT_INTERRUPTABLE mode the caller keeps interrupts disabled across
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the entire cleanup call, so that race window never exists. Additionally,
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every path that resumes a suspended thread (tx_queue_send, tx_queue_receive,
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tx_queue_flush, tx_queue_delete) clears tx_thread_suspend_cleanup before
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calling _tx_thread_system_ni_resume, making a double-cleanup impossible
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under the NI serialisation guarantee. */
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/* Setup pointer to queue control block. */
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queue_ptr = TX_VOID_TO_QUEUE_POINTER_CONVERT(thread_ptr -> tx_thread_suspend_control_block);
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#endif
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/* Yes, we still have thread suspension! */
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/* Clear the suspension cleanup flag. */
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thread_ptr -> tx_thread_suspend_cleanup = TX_NULL;
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/* Decrement the suspended count. */
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queue_ptr -> tx_queue_suspended_count--;
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/* Pickup the suspended count. */
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suspended_count = queue_ptr -> tx_queue_suspended_count;
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/* Remove the suspended thread from the list. */
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/* See if this is the only suspended thread on the list. */
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if (suspended_count == TX_NO_SUSPENSIONS)
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{
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/* Yes, the only suspended thread. */
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/* Update the head pointer. */
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queue_ptr -> tx_queue_suspension_list = TX_NULL;
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}
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else
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{
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/* At least one more thread is on the same suspension list. */
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/* Update the links of the adjacent threads. */
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next_thread = thread_ptr -> tx_thread_suspended_next;
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previous_thread = thread_ptr -> tx_thread_suspended_previous;
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next_thread -> tx_thread_suspended_previous = previous_thread;
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previous_thread -> tx_thread_suspended_next = next_thread;
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/* Determine if we need to update the head pointer. */
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if (queue_ptr -> tx_queue_suspension_list == thread_ptr)
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{
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/* Update the list head pointer. */
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queue_ptr -> tx_queue_suspension_list = next_thread;
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}
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}
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/* Now we need to determine if this cleanup is from a terminate, timeout,
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or from a wait abort. */
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if (thread_ptr -> tx_thread_state == TX_QUEUE_SUSP)
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{
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/* Timeout condition and the thread still suspended on the queue.
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Setup return error status and resume the thread. */
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#ifdef TX_QUEUE_ENABLE_PERFORMANCE_INFO
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/* Increment the total timeouts counter. */
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_tx_queue_performance_timeout_count++;
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/* Increment the number of timeouts on this queue. */
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queue_ptr -> tx_queue_performance_timeout_count++;
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#endif
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/* Setup return status. */
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if (queue_ptr -> tx_queue_enqueued != TX_NO_MESSAGES)
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{
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/* Queue full timeout! */
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thread_ptr -> tx_thread_suspend_status = TX_QUEUE_FULL;
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}
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else
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{
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/* Queue empty timeout! */
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thread_ptr -> tx_thread_suspend_status = TX_QUEUE_EMPTY;
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}
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#ifdef TX_NOT_INTERRUPTABLE
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/* Resume the thread! */
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_tx_thread_system_ni_resume(thread_ptr);
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#else
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/* Temporarily disable preemption. */
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_tx_thread_preempt_disable++;
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/* Restore interrupts. */
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TX_RESTORE
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/* Resume the thread! */
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_tx_thread_system_resume(thread_ptr);
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/* Disable interrupts. */
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TX_DISABLE
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#endif
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}
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#ifndef TX_NOT_INTERRUPTABLE
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}
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}
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}
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}
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}
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/* Restore interrupts. */
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TX_RESTORE
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#endif
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}
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