priority_inversion.c

/* * Copyright (c) 2006-2018, RT-Thread Development Team * * SPDX-License-Identifier: Apache-2.0 * * Change Logs: * Date Author Notes * 2018-08-24 yangjie the first version *//* * 程序清单：互斥量使用例程 * * 这个例子将创建 3 个动态线程以检查持有互斥量时，持有的线程优先级是否 * 被调整到等待线程优先级中的最高优先级。 * * 线程 1，2，3 的优先级从高到低分别被创建， * 线程 3 先持有互斥量，而后线程 2 试图持有互斥量，此时线程 3 的优先级应该 * 被提升为和线程 2 的优先级相同。线程 1 用于检查线程 3 的优先级是否被提升 * 为与线程 2的优先级相同。 */#include <rtthread.h>/* 指向线程控制块的指针 */static rt_thread_t tid1 = RT_NULL;static rt_thread_t tid2 = RT_NULL;static rt_thread_t tid3 = RT_NULL;static rt_mutex_t mutex = RT_NULL;#define THREAD_PRIORITY 10#define THREAD_STACK_SIZE 512#define THREAD_TIMESLICE 5/* 线程 1 入口 */static void thread1_entry(void *parameter){ /* 先让低优先级线程运行 */ rt_thread_mdelay(100); /* 此时 thread3 持有 mutex，并且 thread2 等待持有 mutex */ /* 检查 thread2 与 thread3 的优先级情况 */ if (tid2->current_priority != tid3->current_priority) { /* 优先级不相同，测试失败 */ rt_kprintf("the priority of thread2 is: %d\n", tid2->current_priority); rt_kprintf("the priority of thread3 is: %d\n", tid3->current_priority); rt_kprintf("test failed.\n"); return; } else { rt_kprintf("the priority of thread2 is: %d\n", tid2->current_priority); rt_kprintf("the priority of thread3 is: %d\n", tid3->current_priority); rt_kprintf("test OK.\n"); }}/* 线程 2 入口 */static void thread2_entry(void *parameter){ rt_err_t result; rt_kprintf("the priority of thread2 is: %d\n", tid2->current_priority); /* 先让低优先级线程运行 */ rt_thread_mdelay(50); /* * 试图持有互斥锁，此时 thread3 持有，应把 thread3 的优先级提升 * 到 thread2 相同的优先级 */ result = rt_mutex_take(mutex, RT_WAITING_FOREVER); if (result == RT_EOK) { /* 释放互斥锁 */ rt_mutex_release(mutex); }}/* 线程 3 入口 */static void thread3_entry(void *parameter){ rt_tick_t tick; rt_err_t result; rt_kprintf("the priority of thread3 is: %d\n", tid3->current_priority); result = rt_mutex_take(mutex, RT_WAITING_FOREVER); if (result != RT_EOK) { rt_kprintf("thread3 take a mutex, failed.\n"); } /* 做一个长时间的循环，500ms */ tick = rt_tick_get(); while (rt_tick_get() - tick < (RT_TICK_PER_SECOND / 2)) ; rt_mutex_release(mutex);}int pri_inversion(void){ /* 创建互斥锁 */ mutex = rt_mutex_create("mutex", RT_IPC_FLAG_FIFO); if (mutex == RT_NULL) { rt_kprintf("create dynamic mutex failed.\n"); return -1; } /* 创建线程 1 */ tid1 = rt_thread_create("thread1", thread1_entry, RT_NULL, THREAD_STACK_SIZE, THREAD_PRIORITY - 1, THREAD_TIMESLICE); if (tid1 != RT_NULL) rt_thread_startup(tid1); /* 创建线程 2 */ tid2 = rt_thread_create("thread2", thread2_entry, RT_NULL, THREAD_STACK_SIZE, THREAD_PRIORITY, THREAD_TIMESLICE); if (tid2 != RT_NULL) rt_thread_startup(tid2); /* 创建线程 3 */ tid3 = rt_thread_create("thread3", thread3_entry, RT_NULL, THREAD_STACK_SIZE, THREAD_PRIORITY + 1, THREAD_TIMESLICE); if (tid3 != RT_NULL) rt_thread_startup(tid3); return 0;}/* 导出到 msh 命令列表中 */MSH_CMD_EXPORT(pri_inversion, pri_inversion sample);