linux内核原子操作

OS版本：openEuler 22.03 LTS

架构：x86_64

描述：测试下linux内核驱动常用的几个atomic操作函数。

创建两个内核线程thread_inc和thread_dec，分别调用atomic_inc和atomic_dec函数，atomic_inc每隔1秒调用一次，atomic_dec每隔2秒调用一次，调用完成之后使用atomic_read接口打印atomic值。

代码如下：

// atomic_test.c

#include 
#include 
#include 
#include 
#include 
#include 

static atomic_t A;

static struct task_struct *task_inc = NULL;
static struct task_struct *task_dec = NULL;


static int thread_inc(void * data)
{
    while(!kthread_should_stop()) { // 判读内核线程是否应该停止
        msleep(1000);
		atomic_inc(&A);
    	printk(KERN_INFO "thread_inc is running, now atomic value A is: %d\n",
			   atomic_read(&A));
    }
    return 0;
}

static int thread_dec(void *data)
{
	while (!kthread_should_stop()) {
		msleep(2000);
		atomic_dec(&A);
		printk(KERN_INFO "thread_dec is running, now atomic value A is: %d\n",
			   atomic_read(&A));
	}
	return 0;
}

static int __init atomic_test_init(void)
{
	atomic_set(&A, 0);

	// 创建一个内核线程
    task_inc = kthread_create(thread_inc, NULL, "kthread-inc");
    if (!IS_ERR(task_inc)) {
    	printk(KERN_INFO "create thread success\n");
		wake_up_process(task_inc); // 启动内核线程
    }

	task_dec = kthread_create(thread_dec, NULL, "kthread-dec");
	if (!IS_ERR(task_dec)) {
		printk(KERN_INFO "create thread-dec success\n");
		wake_up_process(task_dec);
	}
    return 0;
}

static void __exit atomic_test_exit(void)
{
    kthread_stop(task_dec); // 停止内核线程
	kthread_stop(task_inc);
    printk(KERN_INFO "atomic_test is stop!\n");
    return;
}

module_init(atomic_test_init);
module_exit(atomic_test_exit);
MODULE_LICENSE("GPL");

Makefile:

obj-m+=atomic_test.o
CONFIG_MODULE_SIG=n
all:
    make -C /lib/modules/$(shell uname -r)/build/ M=$(PWD) modules
clean:
    make -C /lib/modules/$(shell uname -r)/build/ M=$(PWD) clean

输出结果