How to make an infinite time counter in linux driver?

Question

linux

How to make a method call once per second an infinite number of times in a linux driver? You need to call the function once every n milliseconds. The presented example can work out a finite number of times. How to do it indefinitely?

//структуры таймера
static ktime_t tout;
static struct kt_data {
   struct hrtimer timer;
   ktime_t        period;
   int            numb;
} *data;

static enum hrtimer_restart ktfun( struct hrtimer *var ) {
   ktime_t now = var->base->get_time();  // текущее время в типе ktime_t
   printk( KERN_INFO "timer run #%d at jiffies=%ld\n", data->numb, jiffies );
   hrtimer_forward( var, now, tout );
   return data->numb-- > 0 ? HRTIMER_RESTART : HRTIMER_NORESTART;
}

//функция загрузки модуля
static int __init init(void) {
    // Регистрируем драйвер
    major_number = register_chrdev(0, DEVICE_NAME, &fops);

    printk(KERN_ALERT "Hello, I am a pci express device driver! major = %d\n", major_number);

    enum hrtimer_mode mode;
    mode = HRTIMER_MODE_REL;
    tout = ktime_set( 1, 0 );       /* 1 sec. + 0 nsec. */
    data = kmalloc( sizeof(*data), GFP_KERNEL );
    data->period = tout;
    // используем системные часы CLOCK_REALTIME
    hrtimer_init( &data->timer, CLOCK_REALTIME, mode );
    data->timer.function = ktfun;
    data->numb = CLOCK_MONOTONIC;
    printk( KERN_INFO "timer start at jiffies=%ld\n", jiffies );
    hrtimer_start( &data->timer, data->period, mode );

    return 0;
}

//функция выгрузки модуля
static void __exit exit(void) {
    //освобождаем выделенную память
    hrtimer_cancel( &data->timer );
    kfree( data );

    // Освобождаем устройство
    unregister_chrdev(major_number, DEVICE_NAME);
    printk(KERN_ALERT "Goodbye!\n");
}

//регистрация функций загрузки и выгрузки модуля
module_init(init);
module_exit(exit);

Answer 1

Ask yourself what these lines do in your code:

static enum hrtimer_restart ktfun( struct hrtimer *var ) {
   ...
   return data->numb-- > 0 ? HRTIMER_RESTART : HRTIMER_NORESTART;
}
static int __init init(void) {
    ...
    data->numb = CLOCK_MONOTONIC;
    ...
}