中断发送信号量不能释放等待信号量的线程（偶发）

发布于 2024-09-06 14:47:35 浏览：228 订阅该版

MCU为stm32f407vgt6，rt-thread的版本为4.0.3。
1. 代码如下：
```c
/* 接收数据回调函数，该函数会在uart中断例程中调用*/
static rt_err_t modbus_uart_input(rt_device_t dev, rt_size_t size)
{
    /* 串口接收到数据后产生中断， 调用此回调函数， 然后发送接收信号量 */
    rt_sem_release(&modbus_uart_sem);
    return RT_EOK;
}
/* 线程comm uart receive入口 */
void thread_comm_uart_receive_entry(void* parameter)
{
    char ch;
    static uint32_t comm_uart_cmd_buff_pos = 0;
    static uint8_t comm_uart_cmd_buff[MSG_BUFF_LEN];
    while (1)
    {
        /* 从串口读取一个字节的数据,没有读到则等待接收信号量 */
        if(rt_device_read(comm_uart_dev, -1, &ch, 1) == 1) {
            if (ch == END_CHAR) {
                 comm_uart_cmd_buff[comm_uart_cmd_buff_pos] = '\0';
                 if (comm_uart_cmd_buff_pos > 0) {
                     if (comm_uart_cmd_buff[comm_uart_cmd_buff_pos - 1] == BEFOR_END_CHAR) {
                         comm_uart_cmd_buff[--comm_uart_cmd_buff_pos] = '\0';
                     }
                 }
                 /* 接收到一行完整的指令*/
                 CmdHandleMsg(comm_uart_cmd_buff);
                 comm_uart_cmd_buff_pos = 0;
             } else if (ch == BACK_CHAR) {

if (comm_uart_cmd_buff_pos > 0) {
                     comm_uart_cmd_buff[--comm_uart_cmd_buff_pos] = '\0';
                 }
             } else {
                 if (comm_uart_cmd_buff_pos < MSG_BUFF_LEN - 1) {
                     comm_uart_cmd_buff[comm_uart_cmd_buff_pos++] = ch;
                 }
             }
         } else {
             rt_sem_take(&comm_uart_sem, RT_WAITING_FOREVER);
         }
    }
}
```
2. 现象如下，偶尔会出现rt_sem_release发送信号量时，查询挂起线程链表为空，然而thread_comm_uart_receive_entry该线程没有执行，这种现象比较难复现，需要发送很多次数据才会偶尔复现一次。