为什么串口频繁热插拔会导致msg queue收不到消息呢？

串口频繁热插拔，会导致msg queue收不到消息。上代码如下
串口回调函数

static rt_err_t uart_rx_ind(rt_device_t dev, rt_size_t size)
{
rt_uint16_t data_size = size;
rt_mq_send(s_uart_queue,&data_size, 2);
return RT_EOK;
}

串口使用DMA RX 和 DMA TX

rt_device_open(s_uart_device, RT_DEVICE_OFLAG_RDWR |RT_DEVICE_FLAG_DMA_RX | RT_DEVICE_FLAG_DMA_TX); //
rt_device_set_rx_indicate(s_uart_device, uart_rx_ind);
s_uart_queue = rt_mq_create("uart3_Q",2,20,0);
串口数据读取
while (1)
{
/* wait receive */
if (RT_EOK == rt_mq_recv(s_uart_queue,&recv_len,2,RT_WAITING_FOREVER))
{
recv_len = rt_device_read(s_uart_device, 0, s_recv_buf, recv_len);
if ( recv_len > 0 && recv_len <= BUF_LEN)
{
recv_data_process(s_recv_buf,recv_len,s_send_buf + 2,&send_len, RT_TRUE)；
*(rt_uint16_t *)s_send_buf = send_len;
rt_device_write(s_uart_device, 0, s_send_buf, send_len + 2);
}
else
{
LOG_D("uart3 server: receive len error,len=%d\n",recv_len);
}
}
}
正常情况下

线程中rt_mq_recv再也收不到消息，回调函数是一直有执行的，也就是串口是能接收到数据的， 似乎rt_mq_send无法激活线程了，把线程优先级调高也无效。把串口改为中断接收也一样，但是似乎出问题没那么频繁了