Release 4.11 kernel/watchdog.c

/*
 * 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) "NMI watchdog: " fmt

#include <linux/mm.h>
#include <linux/cpu.h>
#include <linux/nmi.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/sysctl.h>
#include <linux/smpboot.h>
#include <linux/sched/rt.h>
#include <uapi/linux/sched/types.h>
#include <linux/tick.h>
#include <linux/workqueue.h>
#include <linux/sched/clock.h>
#include <linux/sched/debug.h>

#include <asm/irq_regs.h>
#include <linux/kvm_para.h>
#include <linux/kthread.h>

static DEFINE_MUTEX(watchdog_proc_mutex);

#if defined(CONFIG_HAVE_NMI_WATCHDOG) || defined(CONFIG_HARDLOCKUP_DETECTOR)

unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED;
#else

unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED;
#endif

int __read_mostly nmi_watchdog_enabled;

int __read_mostly soft_watchdog_enabled;

int __read_mostly watchdog_user_enabled;

int __read_mostly watchdog_thresh = 10;

#ifdef CONFIG_SMP

int __read_mostly sysctl_softlockup_all_cpu_backtrace;

int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
#endif

static struct cpumask watchdog_cpumask __read_mostly;

unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask);

/* Helper for online, unparked cpus. */

#define for_each_watchdog_cpu(cpu) \
	for_each_cpu_and((cpu), cpu_online_mask, &watchdog_cpumask)


atomic_t watchdog_park_in_progress = ATOMIC_INIT(0);

/*
 * The 'watchdog_running' variable is set to 1 when the watchdog threads
 * are registered/started and is set to 0 when the watchdog threads are
 * unregistered/stopped, so it is an indicator whether the threads exist.
 */

static int __read_mostly watchdog_running;
/*
 * If a subsystem has a need to deactivate the watchdog temporarily, it
 * can use the suspend/resume interface to achieve this. The content of
 * the 'watchdog_suspended' variable reflects this state. Existing threads
 * are parked/unparked by the lockup_detector_{suspend|resume} functions
 * (see comment blocks pertaining to those functions for further details).
 *
 * 'watchdog_suspended' also prevents threads from being registered/started
 * or unregistered/stopped via parameters in /proc/sys/kernel, so the state
 * of 'watchdog_running' cannot change while the watchdog is deactivated
 * temporarily (see related code in 'proc' handlers).
 */

static int __read_mostly watchdog_suspended;


static u64 __read_mostly sample_period;

static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
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);
static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt);
static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved);
static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);

static unsigned long soft_lockup_nmi_warn;


unsigned int __read_mostly softlockup_panic =
			CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;



static int __init softlockup_panic_setup(char *str)
{
	softlockup_panic = simple_strtoul(str, NULL, 0);

	return 1;
}
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__setup("softlockup_panic=", softlockup_panic_setup);



static int __init nowatchdog_setup(char *str)
{
	watchdog_enabled = 0;
	return 1;
}
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__setup("nowatchdog", nowatchdog_setup);



static int __init nosoftlockup_setup(char *str)
{
	watchdog_enabled &= ~SOFT_WATCHDOG_ENABLED;
	return 1;
}
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__setup("nosoftlockup", nosoftlockup_setup);

#ifdef CONFIG_SMP


static int __init softlockup_all_cpu_backtrace_setup(char *str)
{
	sysctl_softlockup_all_cpu_backtrace =
		!!simple_strtol(str, NULL, 0);
	return 1;
}
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__setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup);


static int __init hardlockup_all_cpu_backtrace_setup(char *str)
{
	sysctl_hardlockup_all_cpu_backtrace =
		!!simple_strtol(str, NULL, 0);
	return 1;
}
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__setup("hardlockup_all_cpu_backtrace=", hardlockup_all_cpu_backtrace_setup);
#endif

/*
 * Hard-lockup warnings should be triggered after just a few seconds. Soft-
 * lockups can have false positives under extreme conditions. So we generally
 * want a higher threshold for soft lockups than for hard lockups. So we couple
 * the thresholds with a factor: we make the soft threshold twice the amount of
 * time the hard threshold is.
 */


static int get_softlockup_thresh(void)
{
	return watchdog_thresh * 2;
}

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/*
 * Returns seconds, approximately.  We don't need nanosecond
 * resolution, and we don't need to waste time with a big divide when
 * 2^30ns == 1.074s.
 */


static unsigned long get_timestamp(void)
{
	return running_clock() >> 30LL;  /* 2^30 ~= 10^9 */
}

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static void set_sample_period(void)
{
	/*
         * convert watchdog_thresh from seconds to ns
         * the divide by 5 is to give hrtimer several chances (two
         * or three with the current relation between the soft
         * and hard thresholds) to increment before the
         * hardlockup detector generates a warning
         */
	sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5);
}

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/* Commands for resetting the watchdog */


static void __touch_watchdog(void)
{
	__this_cpu_write(watchdog_touch_ts, get_timestamp());
}

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/**
 * touch_softlockup_watchdog_sched - touch watchdog on scheduler stalls
 *
 * Call when the scheduler may have stalled for legitimate reasons
 * preventing the watchdog task from executing - e.g. the scheduler
 * entering idle state.  This should only be used for scheduler events.
 * Use touch_softlockup_watchdog() for everything else.
 */


void touch_softlockup_watchdog_sched(void)
{
	/*
         * Preemption can be enabled.  It doesn't matter which CPU's timestamp
         * gets zeroed here, so use the raw_ operation.
         */
	raw_cpu_write(watchdog_touch_ts, 0);
}

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void touch_softlockup_watchdog(void)
{
	touch_softlockup_watchdog_sched();
	wq_watchdog_touch(raw_smp_processor_id());
}
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EXPORT_SYMBOL(touch_softlockup_watchdog);



void touch_all_softlockup_watchdogs(void)
{
	int cpu;

	/*
         * this is done lockless
         * do we care if a 0 races with a timestamp?
         * all it means is the softlock check starts one cycle later
         */
	for_each_watchdog_cpu(cpu)
		per_cpu(watchdog_touch_ts, cpu) = 0;
	wq_watchdog_touch(-1);
}

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void touch_softlockup_watchdog_sync(void)
{
	__this_cpu_write(softlockup_touch_sync, true);
	__this_cpu_write(watchdog_touch_ts, 0);
}

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/* watchdog detector functions */


bool is_hardlockup(void)
{
	unsigned long hrint = __this_cpu_read(hrtimer_interrupts);

	if (__this_cpu_read(hrtimer_interrupts_saved) == hrint)
		return true;

	__this_cpu_write(hrtimer_interrupts_saved, hrint);
	return false;
}

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static int is_softlockup(unsigned long touch_ts)
{
	unsigned long now = get_timestamp();

	if ((watchdog_enabled & SOFT_WATCHDOG_ENABLED) && watchdog_thresh){
		/* Warn about unreasonable delays. */
		if (time_after(now, touch_ts + get_softlockup_thresh()))
			return now - touch_ts;
	}
	return 0;
}

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static void watchdog_interrupt_count(void)
{
	__this_cpu_inc(hrtimer_interrupts);
}

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/*
 * These two functions are mostly architecture specific
 * defining them as weak here.
 */


int __weak watchdog_nmi_enable(unsigned int cpu)
{
	return 0;
}
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void __weak watchdog_nmi_disable(unsigned int cpu)
{
}

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static int watchdog_enable_all_cpus(void);
static void watchdog_disable_all_cpus(void);

/* watchdog kicker functions */


static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
{
	unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts);
	struct pt_regs *regs = get_irq_regs();
	int duration;
	int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace;

	if (atomic_read(&watchdog_park_in_progress) != 0)
		return HRTIMER_NORESTART;

	/* kick the hardlockup detector */
	watchdog_interrupt_count();

	/* kick the softlockup detector */
	wake_up_process(__this_cpu_read(softlockup_watchdog));

	/* .. and repeat */
	hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period));

	if (touch_ts == 0) {
		if (unlikely(__this_cpu_read(softlockup_touch_sync))) {
			/*
                         * If the time stamp was touched atomically
                         * make sure the scheduler tick is up to date.
                         */
			__this_cpu_write(softlockup_touch_sync, false);
			sched_clock_tick();
		}

		/* Clear the guest paused flag on watchdog reset */
		kvm_check_and_clear_guest_paused();
		__touch_watchdog();
		return HRTIMER_RESTART;
	}

	/* check for a softlockup
         * This is done by making sure a high priority task is
         * being scheduled.  The task touches the watchdog to
         * indicate it is getting cpu time.  If it hasn't then
         * this is a good indication some task is hogging the cpu
         */
	duration = is_softlockup(touch_ts);
	if (unlikely(duration)) {
		/*
                 * If a virtual machine is stopped by the host it can look to
                 * the watchdog like a soft lockup, check to see if the host
                 * stopped the vm before we issue the warning
                 */
		if (kvm_check_and_clear_guest_paused())
			return HRTIMER_RESTART;

		/* only warn once */
		if (__this_cpu_read(soft_watchdog_warn) == true) {
			/*
                         * When multiple processes are causing softlockups the
                         * softlockup detector only warns on the first one
                         * because the code relies on a full quiet cycle to
                         * re-arm.  The second process prevents the quiet cycle
                         * and never gets reported.  Use task pointers to detect
                         * this.
                         */
			if (__this_cpu_read(softlockup_task_ptr_saved) !=
			    current) {
				__this_cpu_write(soft_watchdog_warn, false);
				__touch_watchdog();
			}
			return HRTIMER_RESTART;
		}

		if (softlockup_all_cpu_backtrace) {
			/* Prevent multiple soft-lockup reports if one cpu is already
                         * engaged in dumping cpu back traces
                         */
			if (test_and_set_bit(0, &soft_lockup_nmi_warn)) {
				/* Someone else will report us. Let's give up */
				__this_cpu_write(soft_watchdog_warn, true);
				return HRTIMER_RESTART;
			}
		}

		pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
			smp_processor_id(), duration,
			current->comm, task_pid_nr(current));
		__this_cpu_write(softlockup_task_ptr_saved, current);
		print_modules();
		print_irqtrace_events(current);
		if (regs)
			show_regs(regs);
		else
			dump_stack();

		if (softlockup_all_cpu_backtrace) {
			/* Avoid generating two back traces for current
                         * given that one is already made above
                         */
			trigger_allbutself_cpu_backtrace();

			clear_bit(0, &soft_lockup_nmi_warn);
			/* Barrier to sync with other cpus */
			smp_mb__after_atomic();
		}

		add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK);
		if (softlockup_panic)
			panic("softlockup: hung tasks");
		__this_cpu_write(soft_watchdog_warn, true);
	} else
		__this_cpu_write(soft_watchdog_warn, false);

	return HRTIMER_RESTART;
}

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static void watchdog_set_prio(unsigned int policy, unsigned int prio)
{
	struct sched_param param = { .sched_priority = prio };

	sched_setscheduler(current, policy, &param);
}

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static void watchdog_enable(unsigned int cpu)
{
	struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer);

	/* kick off the timer for the hardlockup detector */
	hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	hrtimer->function = watchdog_timer_fn;

	/* Enable the perf event */
	watchdog_nmi_enable(cpu);

	/* done here because hrtimer_start can only pin to smp_processor_id() */
	hrtimer_start(hrtimer, ns_to_ktime(sample_period),
		      HRTIMER_MODE_REL_PINNED);

	/* initialize timestamp */
	watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1);
	__touch_watchdog();
}

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static void watchdog_disable(unsigned int cpu)
{
	struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer);

	watchdog_set_prio(SCHED_NORMAL, 0);
	hrtimer_cancel(hrtimer);
	/* disable the perf event */
	watchdog_nmi_disable(cpu);
}

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static void watchdog_cleanup(unsigned int cpu, bool online)
{
	watchdog_disable(cpu);
}

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static int watchdog_should_run(unsigned int cpu)
{
	return __this_cpu_read(hrtimer_interrupts) !=
		__this_cpu_read(soft_lockup_hrtimer_cnt);
}

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/*
 * The watchdog thread function - touches the timestamp.
 *
 * It only runs once every sample_period seconds (4 seconds by
 * default) to reset the softlockup timestamp. If this gets delayed
 * for more than 2*watchdog_thresh seconds then the debug-printout
 * triggers in watchdog_timer_fn().
 */


static void watchdog(unsigned int cpu)
{
	__this_cpu_write(soft_lockup_hrtimer_cnt,
			 __this_cpu_read(hrtimer_interrupts));
	__touch_watchdog();

	/*
         * watchdog_nmi_enable() clears the NMI_WATCHDOG_ENABLED bit in the
         * failure path. Check for failures that can occur asynchronously -
         * for example, when CPUs are on-lined - and shut down the hardware
         * perf event on each CPU accordingly.
         *
         * The only non-obvious place this bit can be cleared is through
         * watchdog_nmi_enable(), so a pr_info() is placed there.  Placing a
         * pr_info here would be too noisy as it would result in a message
         * every few seconds if the hardlockup was disabled but the softlockup
         * enabled.
         */
	if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))
		watchdog_nmi_disable(cpu);
}

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static struct smp_hotplug_thread watchdog_threads = {
	.store			= &softlockup_watchdog,
	.thread_should_run	= watchdog_should_run,
	.thread_fn		= watchdog,
	.thread_comm		= "watchdog/%u",
	.setup			= watchdog_enable,
	.cleanup		= watchdog_cleanup,
	.park			= watchdog_disable,
	.unpark			= watchdog_enable,
};

/*
 * park all watchdog threads that are specified in 'watchdog_cpumask'
 *
 * This function returns an error if kthread_park() of a watchdog thread
 * fails. In this situation, the watchdog threads of some CPUs can already
 * be parked and the watchdog threads of other CPUs can still be runnable.
 * Callers are expected to handle this special condition as appropriate in
 * their context.
 *
 * This function may only be called in a context that is protected against
 * races with CPU hotplug - for example, via get_online_cpus().
 */


static int watchdog_park_threads(void)
{
	int cpu, ret = 0;

	atomic_set(&watchdog_park_in_progress, 1);

	for_each_watchdog_cpu(cpu) {
		ret = kthread_park(per_cpu(softlockup_watchdog, cpu));
		if (ret)
			break;
	}

	atomic_set(&watchdog_park_in_progress, 0);

	return ret;
}

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Total
57
100.00%
2
100.00%

/*
 * unpark all watchdog threads that are specified in 'watchdog_cpumask'
 *
 * This function may only be called in a context that is protected against
 * races with CPU hotplug - for example, via get_online_cpus().
 */


static void watchdog_unpark_threads(void)
{
	int cpu;

	for_each_watchdog_cpu(cpu)
		kthread_unpark(per_cpu(softlockup_watchdog, cpu));
}

Contributors
Person
Tokens
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CommitProp
Ulrich Obergfell
25
100.00%
1
100.00%
Total
25
100.00%
1
100.00%

/*
 * Suspend the hard and soft lockup detector by parking the watchdog threads.
 */


int lockup_detector_suspend(void)
{
	int ret = 0;

	get_online_cpus();
	mutex_lock(&watchdog_proc_mutex);
	/*
         * Multiple suspend requests can be active in parallel (counted by
         * the 'watchdog_suspended' variable). If the watchdog threads are
         * running, the first caller takes care that they will be parked.
         * The state of 'watchdog_running' cannot change while a suspend
         * request is active (see related code in 'proc' handlers).
         */
	if (watchdog_running && !watchdog_suspended)
		ret = watchdog_park_threads();

	if (ret == 0)
		watchdog_suspended++;
	else {
		watchdog_disable_all_cpus();
		pr_err("Failed to suspend lockup detectors, disabled\n");
		watchdog_enabled = 0;
	}

	mutex_unlock(&watchdog_proc_mutex);

	return ret;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Ulrich Obergfell
67
100.00%
4
100.00%
Total
67
100.00%
4
100.00%

/*
 * Resume the hard and soft lockup detector by unparking the watchdog threads.
 */


void lockup_detector_resume(void)
{
	mutex_lock(&watchdog_proc_mutex);

	watchdog_suspended--;
	/*
         * The watchdog threads are unparked if they were previously running
         * and if there is no more active suspend request.
         */
	if (watchdog_running && !watchdog_suspended)
		watchdog_unpark_threads();

	mutex_unlock(&watchdog_proc_mutex);
	put_online_cpus();
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Ulrich Obergfell
36
100.00%
3
100.00%
Total
36
100.00%
3
100.00%



static int update_watchdog_all_cpus(void)
{
	int ret;

	ret = watchdog_park_threads();
	if (ret)
		return ret;

	watchdog_unpark_threads();

	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Ulrich Obergfell
19
65.52%
3
75.00%
Michal Hocko
10
34.48%
1
25.00%
Total
29
100.00%
4
100.00%



static int watchdog_enable_all_cpus(void)
{
	int err = 0;

	if (!watchdog_running) {
		err = smpboot_register_percpu_thread_cpumask(&watchdog_threads,
							     &watchdog_cpumask);
		if (err)
			pr_err("Failed to create watchdog threads, disabled\n");
		else
			watchdog_running = 1;
	} else {
		/*
                 * Enable/disable the lockup detectors or
                 * change the sample period 'on the fly'.
                 */
		err = update_watchdog_all_cpus();

		if (err) {
			watchdog_disable_all_cpus();
			pr_err("Failed to update lockup detectors, disabled\n");
		}
	}

	if (err)
		watchdog_enabled = 0;

	return err;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Ulrich Obergfell
28
35.44%
2
22.22%
Frédéric Weisbecker
28
35.44%
3
33.33%
Don Zickus
12
15.19%
1
11.11%
Thomas Gleixner
6
7.59%
1
11.11%
Michal Hocko
4
5.06%
1
11.11%
Marcin Ślusarz
1
1.27%
1
11.11%
Total
79
100.00%
9
100.00%



static void watchdog_disable_all_cpus(void)
{
	if (watchdog_running) {
		watchdog_running = 0;
		smpboot_unregister_percpu_thread(&watchdog_threads);
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Don Zickus
9
37.50%
1
25.00%
Thomas Gleixner
9
37.50%
1
25.00%
Frédéric Weisbecker
6
25.00%
2
50.00%
Total
24
100.00%
4
100.00%

#ifdef CONFIG_SYSCTL

/*
 * Update the run state of the lockup detectors.
 */


static int proc_watchdog_update(void)
{
	int err = 0;

	/*
         * Watchdog threads won't be started if they are already active.
         * The 'watchdog_running' variable in watchdog_*_all_cpus() takes
         * care of this. If those threads are already active, the sample
         * period will be updated and the lockup detectors will be enabled
         * or disabled 'on the fly'.
         */
	if (watchdog_enabled && watchdog_thresh)
		err = watchdog_enable_all_cpus();
	else
		watchdog_disable_all_cpus();

	return err;

}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Ulrich Obergfell
32
100.00%
2
100.00%
Total
32
100.00%
2
100.00%

/*
 * common function for watchdog, nmi_watchdog and soft_watchdog parameter
 *
 * caller             | table->data points to | 'which' contains the flag(s)
 * -------------------|-----------------------|-----------------------------
 * proc_watchdog      | watchdog_user_enabled | NMI_WATCHDOG_ENABLED or'ed
 *                    |                       | with SOFT_WATCHDOG_ENABLED
 * -------------------|-----------------------|-----------------------------
 * proc_nmi_watchdog  | nmi_watchdog_enabled  | NMI_WATCHDOG_ENABLED
 * -------------------|-----------------------|-----------------------------
 * proc_soft_watchdog | soft_watchdog_enabled | SOFT_WATCHDOG_ENABLED
 */


static int proc_watchdog_common(int which, struct ctl_table *table, int write,
				void __user *buffer, size_t *lenp, loff_t *ppos)
{
	int err, old, new;
	int *watchdog_param = (int *)table->data;

	get_online_cpus();
	mutex_lock(&watchdog_proc_mutex);

	if (watchdog_suspended) {
		/* no parameter changes allowed while watchdog is suspended */
		err = -EAGAIN;
		goto out;
	}

	/*
         * If the parameter is being read return the state of the corresponding
         * bit(s) in 'watchdog_enabled', else update 'watchdog_enabled' and the
         * run state of the lockup detectors.
         */
	if (!write) {
		*watchdog_param = (watchdog_enabled & which) != 0;
		err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
	} else {
		err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
		if (err)
			goto out;

		/*
                 * There is a race window between fetching the current value
                 * from 'watchdog_enabled' and storing the new value. During
                 * this race window, watchdog_nmi_enable() can sneak in and
                 * clear the NMI_WATCHDOG_ENABLED bit in 'watchdog_enabled'.
                 * The 'cmpxchg' detects this race and the loop retries.
                 */
		do {
			old = watchdog_enabled;
			/*
                         * If the parameter value is not zero set the
                         * corresponding bit(s), else clear it(them).
                         */
			if (*watchdog_param)
				new = old | which;
			else
				new = old & ~which;
		} while (cmpxchg(&watchdog_enabled, old, new) != old);

		/*
                 * Update the run state of the lockup detectors. There is _no_
                 * need to check the value returned by proc_watchdog_update()
                 * and to restore the previous value of 'watchdog_enabled' as
                 * both lockup detectors are disabled if proc_watchdog_update()
                 * returns an error.
                 */
		if (old == new)
			goto out;

		err = proc_watchdog_update();
	}
out:
	mutex_unlock(&watchdog_proc_mutex);
	put_online_cpus();
	return err;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Ulrich Obergfell
134
65.69%
5
38.46%
Don Zickus
35
17.16%
1
7.69%
Michal Hocko
9
4.41%
1
7.69%
Joshua Hunt
9
4.41%
1
7.69%
Frédéric Weisbecker
6
2.94%
1
7.69%
Mandeep Singh Baines
6
2.94%
2
15.38%
Marcin Ślusarz
4
1.96%
1
7.69%
Chuansheng Liu
1
0.49%
1
7.69%
Total
204
100.00%
13
100.00%

/*
 * /proc/sys/kernel/watchdog
 */


int proc_watchdog(struct ctl_table *table, int write,
		  void __user *buffer, size_t *lenp, loff_t *ppos)
{
	return proc_watchdog_common(NMI_WATCHDOG_ENABLED|SOFT_WATCHDOG_ENABLED,
				    table, write, buffer, lenp, ppos);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Ulrich Obergfell
44
100.00%
1
100.00%
Total
44
100.00%
1
100.00%

/*
 * /proc/sys/kernel/nmi_watchdog
 */


int proc_nmi_watchdog(struct ctl_table *table, int write,
		      void __user *buffer, size_t *lenp, loff_t *ppos)
{
	return proc_watchdog_common(NMI_WATCHDOG_ENABLED,
				    table, write, buffer, lenp, ppos);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Ulrich Obergfell
42
100.00%
1
100.00%
Total
42
100.00%
1
100.00%

/*
 * /proc/sys/kernel/soft_watchdog
 */


int proc_soft_watchdog(struct ctl_table *table, int write,
			void __user *buffer, size_t *lenp, loff_t *ppos)
{
	return proc_watchdog_common(SOFT_WATCHDOG_ENABLED,
				    table, write, buffer, lenp, ppos);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Ulrich Obergfell
42
100.00%
1
100.00%
Total
42
100.00%
1
100.00%

/*
 * /proc/sys/kernel/watchdog_thresh
 */


int proc_watchdog_thresh(struct ctl_table *table, int write,
			 void __user *buffer, size_t *lenp, loff_t *ppos)
{
	int err, old, new;

	get_online_cpus();
	mutex_lock(&watchdog_proc_mutex);

	if (watchdog_suspended) {
		/* no parameter changes allowed while watchdog is suspended */
		err = -EAGAIN;
		goto out;
	}

	old = ACCESS_ONCE(watchdog_thresh);
	err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);

	if (err || !write)
		goto out;

	/*
         * Update the sample period. Restore on failure.
         */
	new = ACCESS_ONCE(watchdog_thresh);
	if (old == new)
		goto out;

	set_sample_period();
	err = proc_watchdog_update();
	if (err) {
		watchdog_thresh = old;
		set_sample_period();
	}
out:
	mutex_unlock(&watchdog_proc_mutex);
	put_online_cpus();
	return err;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Ulrich Obergfell
98
69.50%
5
50.00%
Joshua Hunt
18
12.77%
1
10.00%
Michal Hocko
11
7.80%
2
20.00%
Frédéric Weisbecker
9
6.38%
1
10.00%
Don Zickus
5
3.55%
1
10.00%
Total
141
100.00%
10
100.00%

/*
 * The cpumask is the mask of possible cpus that the watchdog can run
 * on, not the mask of cpus it is actually running on.  This allows the
 * user to specify a mask that will include cpus that have not yet
 * been brought online, if desired.
 */


int proc_watchdog_cpumask(struct ctl_table *table, int write,
			  void __user *buffer, size_t *lenp, loff_t *ppos)
{
	int err;

	get_online_cpus();
	mutex_lock(&watchdog_proc_mutex);

	if (watchdog_suspended) {
		/* no parameter changes allowed while watchdog is suspended */
		err = -EAGAIN;
		goto out;
	}

	err = proc_do_large_bitmap(table, write, buffer, lenp, ppos);
	if (!err && write) {
		/* Remove impossible cpus to keep sysctl output cleaner. */
		cpumask_and(&watchdog_cpumask, &watchdog_cpumask,
			    cpu_possible_mask);

		if (watchdog_running) {
			/*
                         * Failure would be due to being unable to allocate
                         * a temporary cpumask, so we are likely not in a
                         * position to do much else to make things better.
                         */
			if (smpboot_update_cpumask_percpu_thread(
				    &watchdog_threads, &watchdog_cpumask) != 0)
				pr_err("cpumask update failed\n");
		}
	}
out:
	mutex_unlock(&watchdog_proc_mutex);
	put_online_cpus();
	return err;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Chris Metcalf
105
82.03%
1
33.33%
Ulrich Obergfell
23
17.97%
2
66.67%
Total
128
100.00%
3
100.00%

#endif /* CONFIG_SYSCTL */



void __init lockup_detector_init(void)
{
	set_sample_period();

#ifdef CONFIG_NO_HZ_FULL
	if (tick_nohz_full_enabled()) {
		pr_info("Disabling watchdog on nohz_full cores by default\n");
		cpumask_copy(&watchdog_cpumask, housekeeping_mask);
	} else
		cpumask_copy(&watchdog_cpumask, cpu_possible_mask);
#else
	cpumask_copy(&watchdog_cpumask, cpu_possible_mask);
#endif

	if (watchdog_enabled)
		watchdog_enable_all_cpus();
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Chris Metcalf
42
67.74%
1
11.11%
Don Zickus
6
9.68%
1
11.11%
Thomas Gleixner
4
6.45%
1
11.11%
Frédéric Weisbecker
3
4.84%
2
22.22%
Chuansheng Liu
3
4.84%
1
11.11%
Ulrich Obergfell
2
3.23%
2
22.22%
Peter Zijlstra
2
3.23%
1
11.11%
Total
62
100.00%
9
100.00%

Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
Ulrich Obergfell
732
31.44%
20
27.78%
Don Zickus
663
28.48%
6
8.33%
Chris Metcalf
178
7.65%
1
1.39%
Thomas Gleixner
156
6.70%
2
2.78%
Frédéric Weisbecker
119
5.11%
4
5.56%
Aaron Tomlin
110
4.73%
1
1.39%
chai wen
41
1.76%
1
1.39%
Jiri Kosina
39
1.68%
1
1.39%
Michal Hocko
34
1.46%
2
2.78%
Joshua Hunt
34
1.46%
2
2.78%
Christoph Lameter
33
1.42%
2
2.78%
Babu Moger
30
1.29%
2
2.78%
Mandeep Singh Baines
27
1.16%
4
5.56%
Tejun Heo
27
1.16%
2
2.78%
Chuansheng Liu
20
0.86%
2
2.78%
Ingo Molnar
17
0.73%
5
6.94%
Eric B Munson
16
0.69%
1
1.39%
Björn Mork
16
0.69%
1
1.39%
Andrew Morton
9
0.39%
2
2.78%
Peter Zijlstra
8
0.34%
2
2.78%
Marcin Ślusarz
6
0.26%
3
4.17%
Clark Williams
3
0.13%
1
1.39%
Yaowei Bai
3
0.13%
1
1.39%
Namhyung Kim
3
0.13%
1
1.39%
Fernando Luis Vázquez Cao
2
0.09%
1
1.39%
Cyril Bur
1
0.04%
1
1.39%
Fabian Frederick
1
0.04%
1
1.39%
Total
2328
100.00%
72
100.00%
Directory: kernel

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