linux内核研究--watchdog实现分析

/kernel/watchdog.c

tatic DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);  //记录是时间戳，主要在watchdog线程中更新

static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);

static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer);

static DEFINE_PER_CPU(bool, softlockup_touch_sync);

static DEFINE_PER_CPU(bool, soft_watchdog_warn);

static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);   //在hrtimer处理函数中更新

static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt);

static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved);

#ifdef CONFIG_HARDLOCKUP_DETECTOR

static DEFINE_PER_CPU(bool, hard_watchdog_warn);

static DEFINE_PER_CPU(bool, watchdog_nmi_touch);

static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);  //在is_hardlockup中更新，更新为hrtimer_interrupts

static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);

 

 

/* Commands for resetting the watchdog */

static void __touch_watchdog(void)

{

__this_cpu_write(watchdog_touch_ts, get_timestamp());

}

static void watchdog(unsigned int cpu)

{

__this_cpu_write(soft_lockup_hrtimer_cnt,

 __this_cpu_read(hrtimer_interrupts));

__touch_watchdog();

}

static struct smp_hotplug_thread watchdog_threads = {

.store                        = &softlockup_watchdog,

.thread_should_run        = watchdog_should_run,

.thread_fn                = watchdog,                                //线程函数就是更新当前CPU的watchdog_touch_ts变量的值

.thread_comm                = "watchdog/%u",

.setup                        = watchdog_enable,

.cleanup                = watchdog_cleanup,

.park                        = watchdog_disable,

.unpark                        = watchdog_enable,

};