linux-6.15/kernel/watchdog.c

1 // SPDX-License-Identifier: GPL-2.0
9  * Some chunks also taken from the old x86-specific nmi watchdog code, thanks
29 #include <linux/sched/clock.h>
62  * Should we panic when a soft-lockup or hard-lockup occurs:
177 		 * Prevent multiple hard-lockup reports if one cpu is already  in watchdog_hardlockup_check()
242  * Watchdog-detector specific API.
250 	return -ENODEV;  in watchdog_hardlockup_probe()
254  * watchdog_hardlockup_stop - Stop the watchdog for reconfiguration
264  * watchdog_hardlockup_start - Start the watchdog after reconfiguration
270  * - watchdog_enabled
271  * - watchdog_thresh
272  * - watchdog_cpumask
277  * lockup_detector_update_enable - Update the sysctl enable bit
378 	return data_ns >> 24LL; /* 2^24ns ~= 16.8ms */  in get_16bit_precision()
396 		util = DIV_ROUND_UP(100 * (new_stat - old_stat), sample_period_16);  in update_cpustat()
462 	tail = (tail + NUM_HARDIRQ_REPORT - 1) % NUM_HARDIRQ_REPORT;  in need_counting_irqs()
484 		{-1, 0}, {-1, 0}, {-1, 0}, {-1, 0}, {-1, 0}  in print_irq_counts()
502 			if (irq_counts_sorted[i].irq == -1)  in print_irq_counts()
505 			printk(KERN_CRIT "\t#%u: %-10u\tirq#%d\n",  in print_irq_counts()
533  * Hard-lockup warnings should be triggered after just a few seconds. Soft-
547  * 2^30ns == 1.074s.
557 	 * convert watchdog_thresh from seconds to ns  in set_sample_period()
580  * touch_softlockup_watchdog_sched - touch watchdog on scheduler stalls
583  * preventing the watchdog task from executing - e.g. the scheduler
646 		 * A poorly behaving BPF scheduler can live-lock the system into  in is_softlockup()
651 			scx_softlockup(now - touch_ts);  in is_softlockup()
655 			return now - touch_ts;  in is_softlockup()
665  * The watchdog feed function - touches the timestamp.
669  * for more than 2*watchdog_thresh seconds then the debug-printout
686 	int duration;  in watchdog_timer_fn()  local
743 	duration = is_softlockup(touch_ts, period_ts, now);  in watchdog_timer_fn()
744 	if (unlikely(duration)) {  in watchdog_timer_fn()
746 		 * Prevent multiple soft-lockup reports if one cpu is already  in watchdog_timer_fn()
758 		pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",  in watchdog_timer_fn()
759 			smp_processor_id(), duration,  in watchdog_timer_fn()
760 			current->comm, task_pid_nr(current));  in watchdog_timer_fn()
936  * lockup_detector_soft_poweroff - Interface to stop lockup detector(s)
959  * caller             | table->data points to            | 'which'
960  * -------------------|----------------------------------|-------------------------------
963  * -------------------|----------------------------------|-------------------------------
965  * -------------------|----------------------------------|-------------------------------
971 	int err, old, *param = table->data;  in proc_watchdog_common()
1011 		return -ENOTSUPP;  in proc_nmi_watchdog()
1189 		if (ret == -ENODEV)  in lockup_detector_delay_init()
1204  * lockup_detector_retry_init - retry init lockup detector if possible.