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328
common/src/tx_mutex_priority_change.c
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328
common/src/tx_mutex_priority_change.c
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/**************************************************************************/
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/* */
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/* Copyright (c) Microsoft Corporation. All rights reserved. */
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/* */
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/* This software is licensed under the Microsoft Software License */
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/* Terms for Microsoft Azure RTOS. Full text of the license can be */
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/* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */
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/* and in the root directory of this software. */
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/* */
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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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/** Mutex */
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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_mutex.h"
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/**************************************************************************/
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/* */
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/* FUNCTION RELEASE */
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/* */
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/* _tx_mutex_priority_change PORTABLE C */
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/* 6.0 */
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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 changes the priority of the specified thread for the */
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/* priority inheritance option of the mutex service. */
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/* */
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/* INPUT */
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/* */
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/* thread_ptr Pointer to thread to suspend */
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/* new_priority New thread priority */
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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 */
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/* _tx_thread_system_ni_resume Non-interruptable resume thread */
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/* _tx_thread_system_suspend Suspend thread */
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/* _tx_thread_system_ni_suspend Non-interruptable suspend thread */
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/* */
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/* CALLED BY */
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/* */
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/* _tx_mutex_get Inherit priority */
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/* _tx_mutex_put Restore previous priority */
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/* */
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/* RELEASE HISTORY */
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/* */
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/* DATE NAME DESCRIPTION */
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/* */
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/* 05-19-2020 William E. Lamie Initial Version 6.0 */
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/* */
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/**************************************************************************/
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VOID _tx_mutex_priority_change(TX_THREAD *thread_ptr, UINT new_priority)
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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_THREAD *execute_ptr;
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TX_THREAD *next_execute_ptr;
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UINT original_priority;
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#ifndef TX_DISABLE_PREEMPTION_THRESHOLD
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ULONG priority_bit;
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#if TX_MAX_PRIORITIES > 32
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UINT map_index;
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#endif
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#endif
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#ifndef TX_NOT_INTERRUPTABLE
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/* Lockout interrupts while the thread is being suspended. */
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TX_DISABLE
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#endif
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/* Determine if this thread is currently ready. */
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if (thread_ptr -> tx_thread_state != TX_READY)
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{
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/* Change thread priority to the new mutex priority-inheritance priority. */
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thread_ptr -> tx_thread_priority = new_priority;
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/* Determine how to setup the thread's preemption-threshold. */
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if (thread_ptr -> tx_thread_user_preempt_threshold < new_priority)
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{
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/* Change thread preemption-threshold to the user's preemption-threshold. */
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thread_ptr -> tx_thread_preempt_threshold = thread_ptr -> tx_thread_user_preempt_threshold;
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}
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else
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{
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/* Change the thread preemption-threshold to the new threshold. */
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thread_ptr -> tx_thread_preempt_threshold = new_priority;
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}
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#ifndef TX_NOT_INTERRUPTABLE
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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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else
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{
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/* Pickup the next thread to execute. */
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execute_ptr = _tx_thread_execute_ptr;
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/* Save the original priority. */
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original_priority = thread_ptr -> tx_thread_priority;
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#ifdef TX_NOT_INTERRUPTABLE
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/* Increment the preempt disable flag. */
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_tx_thread_preempt_disable++;
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/* Set the state to suspended. */
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thread_ptr -> tx_thread_state = TX_SUSPENDED;
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/* Call actual non-interruptable thread suspension routine. */
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_tx_thread_system_ni_suspend(thread_ptr, ((ULONG) 0));
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/* At this point, the preempt disable flag is still set, so we still have
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protection against all preemption. */
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/* Change thread priority to the new mutex priority-inheritance priority. */
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thread_ptr -> tx_thread_priority = new_priority;
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/* Determine how to setup the thread's preemption-threshold. */
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if (thread_ptr -> tx_thread_user_preempt_threshold < new_priority)
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{
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/* Change thread preemption-threshold to the user's preemption-threshold. */
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thread_ptr -> tx_thread_preempt_threshold = thread_ptr -> tx_thread_user_preempt_threshold;
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}
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else
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{
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/* Change the thread preemption-threshold to the new threshold. */
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thread_ptr -> tx_thread_preempt_threshold = new_priority;
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}
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/* Resume the thread with the new priority. */
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_tx_thread_system_ni_resume(thread_ptr);
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/* Decrement the preempt disable flag. */
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_tx_thread_preempt_disable--;
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#else
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/* Increment the preempt disable flag. */
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_tx_thread_preempt_disable = _tx_thread_preempt_disable + ((UINT) 2);
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/* Set the state to suspended. */
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thread_ptr -> tx_thread_state = TX_SUSPENDED;
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/* Set the suspending flag. */
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thread_ptr -> tx_thread_suspending = TX_TRUE;
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/* Setup the timeout period. */
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thread_ptr -> tx_thread_timer.tx_timer_internal_remaining_ticks = ((ULONG) 0);
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/* Restore interrupts. */
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TX_RESTORE
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/* The thread is ready and must first be removed from the list. Call the
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system suspend function to accomplish this. */
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_tx_thread_system_suspend(thread_ptr);
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/* Disable interrupts. */
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TX_DISABLE
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/* At this point, the preempt disable flag is still set, so we still have
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protection against all preemption. */
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/* Change thread priority to the new mutex priority-inheritance priority. */
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thread_ptr -> tx_thread_priority = new_priority;
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/* Determine how to setup the thread's preemption-threshold. */
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if (thread_ptr -> tx_thread_user_preempt_threshold < new_priority)
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{
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/* Change thread preemption-threshold to the user's preemption-threshold. */
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thread_ptr -> tx_thread_preempt_threshold = thread_ptr -> tx_thread_user_preempt_threshold;
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}
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else
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{
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/* Change the thread preemption-threshold to the new threshold. */
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thread_ptr -> tx_thread_preempt_threshold = new_priority;
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}
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/* Restore interrupts. */
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TX_RESTORE
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/* Resume the thread with the new priority. */
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_tx_thread_system_resume(thread_ptr);
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#endif
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/* Optional processing extension. */
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TX_MUTEX_PRIORITY_CHANGE_EXTENSION
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#ifndef TX_NOT_INTERRUPTABLE
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/* Disable interrupts. */
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TX_DISABLE
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#endif
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/* Pickup the next thread to execute. */
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next_execute_ptr = _tx_thread_execute_ptr;
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/* Determine if this thread is not the next thread to execute. */
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if (thread_ptr != next_execute_ptr)
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{
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/* Make sure the thread is still ready. */
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if (thread_ptr -> tx_thread_state == TX_READY)
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{
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/* Now check and see if this thread has an equal or higher priority. */
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if (thread_ptr -> tx_thread_priority <= next_execute_ptr -> tx_thread_priority)
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{
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/* Now determine if this thread was the previously executing thread. */
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if (thread_ptr == execute_ptr)
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{
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/* Yes, this thread was previously executing before we temporarily suspended and resumed
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it in order to change the priority. A lower or same priority thread cannot be the next thread
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to execute in this case since this thread really didn't suspend. Simply reset the execute
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pointer to this thread. */
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_tx_thread_execute_ptr = thread_ptr;
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/* Determine if we moved to a lower priority. If so, move the thread to the front of its priority list. */
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if (original_priority < new_priority)
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{
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/* Ensure that this thread is placed at the front of the priority list. */
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_tx_thread_priority_list[thread_ptr -> tx_thread_priority] = thread_ptr;
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}
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}
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}
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else
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{
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/* Now determine if this thread's preemption-threshold needs to be enforced. */
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if (thread_ptr -> tx_thread_preempt_threshold < thread_ptr -> tx_thread_priority)
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{
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/* Yes, preemption-threshold is in force for this thread. */
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/* Compare the next thread to execute thread's priority against the thread's preemption-threshold. */
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if (thread_ptr -> tx_thread_preempt_threshold <= next_execute_ptr -> tx_thread_priority)
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{
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/* We must swap execute pointers to enforce the preemption-threshold of a thread coming out of
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priority inheritance. */
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_tx_thread_execute_ptr = thread_ptr;
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/* Determine if we moved to a lower priority. If so, move the thread to the front of its priority list. */
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if (original_priority < new_priority)
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{
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/* Ensure that this thread is placed at the front of the priority list. */
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_tx_thread_priority_list[thread_ptr -> tx_thread_priority] = thread_ptr;
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}
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}
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#ifndef TX_DISABLE_PREEMPTION_THRESHOLD
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else
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{
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/* In this case, we need to mark the preempted map to indicate a thread executed above the
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preemption-threshold. */
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#if TX_MAX_PRIORITIES > 32
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/* Calculate the index into the bit map array. */
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map_index = (next_execute_ptr -> tx_thread_priority)/ ((UINT) 32);
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/* Set the active bit to remember that the preempt map has something set. */
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TX_DIV32_BIT_SET(next_execute_ptr -> tx_thread_priority, priority_bit)
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_tx_thread_preempted_map_active = _tx_thread_preempted_map_active | priority_bit;
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#endif
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/* Remember that this thread was preempted by a thread above the thread's threshold. */
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TX_MOD32_BIT_SET(next_execute_ptr -> tx_thread_priority, priority_bit)
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_tx_thread_preempted_maps[MAP_INDEX] = _tx_thread_preempted_maps[MAP_INDEX] | priority_bit;
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}
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#endif
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}
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}
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}
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}
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#ifndef TX_NOT_INTERRUPTABLE
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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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}
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