内核定时任务学习实例

helight

/*
*kernel module
*char device
*mytimer.c
*/
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define DEVICE_NAME "chardev"
static ssize_t chardev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos);
static struct file_operations chardev_fops = {
            .read = chardev_read,
};
static struct cdev *cdevp = NULL;
static dev_t devno;
static wait_queue_head_t queue;
static int flag = 0;
static struct timer_list timer;
static void timer_callback(unsigned long arg)
{
    printk("callback...%ld %ld\n",timer.expires,jiffies);
    flag = 1;
    struct task_struct *p=(struct task_struct *)arg;
    wake_up_interruptible(&queue);
    //wake_up_process(p);
}
static ssize_t chardev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
{
    char sendbuf[] = "hello world";
    init_timer(&timer);
    timer.expires = jiffies + HZ * 20;
    timer.data =(unsigned long)current;
    timer.function = timer_callback;
    add_timer(&timer);
    printk(" HZ...%d\n",HZ);
    printk(" befoer schedule...%ld %ld\n",timer.expires,jiffies);
    wait_event_interruptible(queue, flag != 0);
    //schedule();
    printk("time out...%ld %ld\n",timer.expires,jiffies);
    flag = 0;
    del_timer(&timer);
    copy_to_user(buf, sendbuf, strlen(sendbuf));
    return strlen(res);
}
static int __init chardev_init(void)
{
    int ret;
    ret = alloc_chrdev_region(&devno, 0, 1, DEVICE_NAME);
    if (ret
#include
#include
#include
#include
int main()
{
    int fd=0;
    int rf=0;
    char buf[15];
    fd=open("/dev/chardev",O_RDWR);
    if ( fd == -1 )
        {
          printf("Cann't open file \n");
          exit(0);
        }
    memset(buf, 0, sizeof(buf));
    rf=read(fd,buf,12);
    if(rf

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