高手进阶：Linux系统下内核定时器的用法

;总的来说，timer的用法还是很简单的。主要需要定义一个timer_list变量timer、先初始化timer init_timer(&timer); then 对timer的相关参数赋值： timer.function = fun; timer.expires = jiffies + TIMER_DELAY; add_timer(&timer); 在定时器时间到的时候，会执行fun，如果继续定时，可以通过 在fun中执行 mod_timer(&timer, jiffies + TIMER_DELAY); 在不需要的时候通过调用 del_timer(&timer); 删除定时器。 简单吧。这样一个简单的定时器就完成了。 呵呵。 附程序： #include <linux/module.h>#include <linux/types.h>#include <linux/fs.h>#include <linux/errno.h>#include <linux/mm.h>#include <linux/sched.h>#include <linux/init.h>#include <linux/cdev.h>#include <asm/io.h>#include <asm/system.h>#include <asm/uaccess.h>#include <linux/timer.h>#include <asm/atomic.h>#define SECOND_MAJOR 0static int second_major = SECOND_MAJOR;struct second_dev{struct cdev cdev;atomic_t counter;struct timer_list s_timer;};struct second_dev *second_devp;static void second_timer_handle(unsigned long arg){mod_timer(&second_devp->s_timer, jiffies + HZ);atomic_inc(&second_devp->counter);printk(KERN_ERR 'current jiffies is %ldn',jiffies);}int second_open(struct inode *inode, struct file *filp){init_timer(&second_devp->s_timer);second_devp->s_timer.function = &second_timer_handle;second_devp->s_timer.expires = jiffies + HZ;add_timer(&second_devp->s_timer);atomic_set(&second_devp->counter, 0);return 0; }int second_release(struct inode *inode, struct file *filp){del_timer(&second_devp->s_timer);return 0;}static ssize_t second_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos){int counter;counter = atomic_read(&second_devp->counter);if (put_user(counter, (int *)buf)){return -EFAULT;}else{return sizeof(unsigned int);}}static const struct file_operations second_fops ={.owner = THIS_MODULE,.open = second_open,.release = second_release,.read = second_read,};static void second_setup_cdev(struct second_dev *dev, int index){int err, devno = MKDEV(second_major, index);cdev_init(&dev->cdev, &second_fops);dev->cdev.owner = THIS_MODULE;dev->cdev.ops = &second_fops;err = cdev_add(&dev->cdev, devno, 1);if (err){printk(KERN_NOTICE 'Error %d add second%d', err, index);}}int second_init(void){int ret;dev_t devno = MKDEV(second_major, 0);if (second_major){ret = register_chrdev_region(devno, 1, 'second');}else{ret = alloc_chrdev_region(&devno, 0, 1, 'second');second_major = MAJOR(devno);}if (ret < 0){return ret;}second_devp = kmalloc(sizeof(struct second_dev), GFP_KERNEL);if (!second_devp){ret = -ENOMEM;goto fail_malloc;}memset(second_devp, 0, sizeof(struct second_dev));second_setup_cdev(second_devp, 0);return 0;fail_malloc:unregister_chrdev_region(devno, 1);}void second_exit(void){cdev_del(&second_devp->cdev);kfree(second_devp);unregister_chrdev_region(MKDEV(second_major, 0), 1);}MODULE_AUTHOR('Song Baohua');MODULE_LICENSE('Dual BSD/GPL');module_param(second_major, int, S_IRUGO);module_init(second_init);module_exit(second_exit);附上用户端的测试程序：#include <stdio.h>#include <unistd.h>#include <fcntl.h>int main(void){int fd, i;int data;fd = open('/dev/second',O_RDONLY);if (fd < 0){printf('open /dev/second errorn');}for(i = 0; i < 20; i++){read(fd, &data, sizeof(data));printf('read /dev/second is %dn',data);sleep(1);}close(fd);}