linux定时器使用

struct timer_list {
  /*
   * All fields that change during normal runtime grouped to the
   * same cacheline
   */
  struct list_head entry; //定时器的链表
  unsigned long expires;//以节拍为单位的定时时间，表示为定时器触发的到期时间
  struct tvec_base *base;

  void (*function)(unsigned long); //该指针指向定时器处理函数，函数参数为长整形
  unsigned long data; //处理函数的参数值

  int slack;

#ifdef CONFIG_TIMER_STATS
  void *start_site;
  char start_comm[16];
  int start_pid;
#endif
#ifdef CONFIG_LOCKDEP
  struct lockdep_map lockdep_map;
#endif
};

void add_timer(struct timer_list *timer)
{
  BUG_ON(timer_pending(timer));
  mod_timer(timer, timer->expires); //该函数设置定时器timer的定时时间为timer->expires;
}

#include< linux/module.h >
#include< linux/init.h >
#include< linux/sched.h >
#include < linux/timer.h >

#include < linux/kernel.h >

struct timer_list stimer; //定义定时器
static void time_handler(unsigned long data){ //定时器处理函数
  mod_timer(&stimer, jiffies + HZ);
  printk(“current jiffies is %ld\n”, jiffies);
}
static int __init timer_init(void){ //定时器初始化过程
  printk(“My module worked!\n”);
  init_timer(&stimer);
  stimer.data = 0;
  stimer.expires = jiffies + HZ; //设置到期时间
  stimer.function = time_handler;
  add_timer(&stimer);
  return 0;
}
static void __exit timer_exit(void){
  printk(“Unloading my module.\n”);
  del_timer(&stimer);//删除定时器
  return;
}
module_init(timer_init);//加载模块
module_exit(timer_exit);//卸载模块

MODULE_AUTHOR(“fyf”);

MODULE_LICENSE(“GPL”);

#include< linux/module.h >
#include< linux/init.h >
#include< linux/sched.h >
#include < linux/timer.h >
#include < linux/kernel.h >
struct timer_list stimer; //定义定时器
int timeout = 10 * HZ;
static void time_handler(unsigned long data){ //定时器处理函数，执行该函数获取挂起进程的pid，唤醒该进程
  struct task_struct *p = (struct task_struct *)data;//参数为挂起进程pid
  wake_up_process(p);//唤醒进程
  printk(“current jiffies is %ld\n”, jiffies); //打印当前jiffies
}
static int __init timer_init(void){ //定时器初始化过程
  printk(“My module worked!\n”);
  init_timer(&stimer);
  stimer.data = (unsigned long)current; //将当前进程的pid作为参数传递
  stimer.expires = jiffies + timeout; //设置到期时间
  stimer.function = time_handler;
  add_timer(&stimer);
  printk(“current jiffies is %ld\n”, jiffies);
  set_current_state(TASK_INTERRUPTIBLE);
  schedule(); //挂起该进程
  del_timer(&stimer); //删除定时器
  return 0;
}
static void __exit timer_exit(void){
  printk(“Unloading my module.\n”);
  return;
}
module_init(timer_init);//加载模块
module_exit(timer_exit);//卸载模块
MODULE_AUTHOR(“fyf”);
MODULE_LICENSE(“GPL”);