path: root/kernel/watchdog.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Detect hard and soft lockups on a system
 *
 * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
 *
 * Note: Most of this code is borrowed heavily from the original softlockup
 * detector, so thanks to Ingo for the initial implementation.
 * Some chunks also taken from the old x86-specific nmi watchdog code, thanks
 * to those contributors as well.
 */

#define pr_fmt(fmt) "watchdog: " fmt

#include <linux/cpu.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/irqdesc.h>
#include <linux/kernel_stat.h>
#include <linux/kvm_para.h>
#include <linux/math64.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/nmi.h>
#include <linux/stop_machine.h>
#include <linux/sysctl.h>
#include <linux/tick.h>
#include <linux/sys_info.h>

#include <linux/sched/clock.h>
#include <linux/sched/debug.h>
#include <linux/sched/isolation.h>

#include <asm/irq_regs.h>

static DEFINE_MUTEX(watchdog_mutex);

#if defined(CONFIG_HARDLOCKUP_DETECTOR) || defined(CONFIG_HARDLOCKUP_DETECTOR_SPARC64)
# define WATCHDOG_HARDLOCKUP_DEFAULT	1
#else
# define WATCHDOG_HARDLOCKUP_DEFAULT	0
#endif

#define NUM_SAMPLE_PERIODS	5

unsigned long __read_mostly watchdog_enabled;
int __read_mostly watchdog_user_enabled = 1;
static int __read_mostly watchdog_hardlockup_user_enabled = WATCHDOG_HARDLOCKUP_DEFAULT;
static int __read_mostly watchdog_softlockup_user_enabled = 1;
int __read_mostly watchdog_thresh = 10;
static int __read_mostly watchdog_thresh_next;
static int __read_mostly watchdog_hardlockup_available;

struct cpumask watchdog_cpumask __read_mostly;
unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask);

#ifdef CONFIG_HARDLOCKUP_DETECTOR

# ifdef CONFIG_SMP
int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
# endif /* CONFIG_SMP */

/*
 * Should we panic when a soft-lockup or hard-lockup occurs:
 */
unsigned int __read_mostly hardlockup_panic =
			IS_ENABLED(CONFIG_BOOTPARAM_HARDLOCKUP_PANIC);

/*
 * bitmasks to control what kinds of system info to be printed when
 * hard lockup is detected, it could be task, memory, lock etc.
 * Refer include/linux/sys_info.h for detailed bit definition.
 */
unsigned long hardlockup_si_mask;

#ifdef CONFIG_SYSFS

static unsigned int hardlockup_count;

static ssize_t hardlockup_count_show(struct kobject *kobj, struct kobj_attribute *attr,
				     char *page)
{
	return sysfs_emit(page, "%u\n", hardlockup_count);
}