mirror of https://gitee.com/openkylin/linux.git
594 lines
14 KiB
C
594 lines
14 KiB
C
/*
|
|
* Detect hard and soft lockups on a system
|
|
*
|
|
* started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
|
|
*
|
|
* this code detects hard lockups: incidents in where on a CPU
|
|
* the kernel does not respond to anything except NMI.
|
|
*
|
|
* Note: Most of this code is borrowed heavily from softlockup.c,
|
|
* so thanks to Ingo for the initial implementation.
|
|
* Some chunks also taken from arch/x86/kernel/apic/nmi.c, thanks
|
|
* to those contributors as well.
|
|
*/
|
|
|
|
#include <linux/mm.h>
|
|
#include <linux/cpu.h>
|
|
#include <linux/nmi.h>
|
|
#include <linux/init.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/freezer.h>
|
|
#include <linux/kthread.h>
|
|
#include <linux/lockdep.h>
|
|
#include <linux/notifier.h>
|
|
#include <linux/module.h>
|
|
#include <linux/sysctl.h>
|
|
|
|
#include <asm/irq_regs.h>
|
|
#include <linux/perf_event.h>
|
|
|
|
int watchdog_enabled = 1;
|
|
int __read_mostly watchdog_thresh = 10;
|
|
|
|
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);
|
|
#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);
|
|
static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);
|
|
static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
|
|
#endif
|
|
|
|
/* boot commands */
|
|
/*
|
|
* Should we panic when a soft-lockup or hard-lockup occurs:
|
|
*/
|
|
#ifdef CONFIG_HARDLOCKUP_DETECTOR
|
|
static int hardlockup_panic =
|
|
CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
|
|
|
|
static int __init hardlockup_panic_setup(char *str)
|
|
{
|
|
if (!strncmp(str, "panic", 5))
|
|
hardlockup_panic = 1;
|
|
else if (!strncmp(str, "nopanic", 7))
|
|
hardlockup_panic = 0;
|
|
else if (!strncmp(str, "0", 1))
|
|
watchdog_enabled = 0;
|
|
return 1;
|
|
}
|
|
__setup("nmi_watchdog=", hardlockup_panic_setup);
|
|
#endif
|
|
|
|
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;
|
|
}
|
|
__setup("softlockup_panic=", softlockup_panic_setup);
|
|
|
|
static int __init nowatchdog_setup(char *str)
|
|
{
|
|
watchdog_enabled = 0;
|
|
return 1;
|
|
}
|
|
__setup("nowatchdog", nowatchdog_setup);
|
|
|
|
/* deprecated */
|
|
static int __init nosoftlockup_setup(char *str)
|
|
{
|
|
watchdog_enabled = 0;
|
|
return 1;
|
|
}
|
|
__setup("nosoftlockup", nosoftlockup_setup);
|
|
/* */
|
|
|
|
/*
|
|
* 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()
|
|
{
|
|
return watchdog_thresh * 2;
|
|
}
|
|
|
|
/*
|
|
* 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(int this_cpu)
|
|
{
|
|
return cpu_clock(this_cpu) >> 30LL; /* 2^30 ~= 10^9 */
|
|
}
|
|
|
|
static unsigned long get_sample_period(void)
|
|
{
|
|
/*
|
|
* convert watchdog_thresh from seconds to ns
|
|
* the divide by 5 is to give hrtimer 5 chances to
|
|
* increment before the hardlockup detector generates
|
|
* a warning
|
|
*/
|
|
return get_softlockup_thresh() * (NSEC_PER_SEC / 5);
|
|
}
|
|
|
|
/* Commands for resetting the watchdog */
|
|
static void __touch_watchdog(void)
|
|
{
|
|
int this_cpu = smp_processor_id();
|
|
|
|
__this_cpu_write(watchdog_touch_ts, get_timestamp(this_cpu));
|
|
}
|
|
|
|
void touch_softlockup_watchdog(void)
|
|
{
|
|
__this_cpu_write(watchdog_touch_ts, 0);
|
|
}
|
|
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_online_cpu(cpu)
|
|
per_cpu(watchdog_touch_ts, cpu) = 0;
|
|
}
|
|
|
|
#ifdef CONFIG_HARDLOCKUP_DETECTOR
|
|
void touch_nmi_watchdog(void)
|
|
{
|
|
if (watchdog_enabled) {
|
|
unsigned cpu;
|
|
|
|
for_each_present_cpu(cpu) {
|
|
if (per_cpu(watchdog_nmi_touch, cpu) != true)
|
|
per_cpu(watchdog_nmi_touch, cpu) = true;
|
|
}
|
|
}
|
|
touch_softlockup_watchdog();
|
|
}
|
|
EXPORT_SYMBOL(touch_nmi_watchdog);
|
|
|
|
#endif
|
|
|
|
void touch_softlockup_watchdog_sync(void)
|
|
{
|
|
__raw_get_cpu_var(softlockup_touch_sync) = true;
|
|
__raw_get_cpu_var(watchdog_touch_ts) = 0;
|
|
}
|
|
|
|
#ifdef CONFIG_HARDLOCKUP_DETECTOR
|
|
/* watchdog detector functions */
|
|
static int is_hardlockup(void)
|
|
{
|
|
unsigned long hrint = __this_cpu_read(hrtimer_interrupts);
|
|
|
|
if (__this_cpu_read(hrtimer_interrupts_saved) == hrint)
|
|
return 1;
|
|
|
|
__this_cpu_write(hrtimer_interrupts_saved, hrint);
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
static int is_softlockup(unsigned long touch_ts)
|
|
{
|
|
unsigned long now = get_timestamp(smp_processor_id());
|
|
|
|
/* Warn about unreasonable delays: */
|
|
if (time_after(now, touch_ts + get_softlockup_thresh()))
|
|
return now - touch_ts;
|
|
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_HARDLOCKUP_DETECTOR
|
|
static struct perf_event_attr wd_hw_attr = {
|
|
.type = PERF_TYPE_HARDWARE,
|
|
.config = PERF_COUNT_HW_CPU_CYCLES,
|
|
.size = sizeof(struct perf_event_attr),
|
|
.pinned = 1,
|
|
.disabled = 1,
|
|
};
|
|
|
|
/* Callback function for perf event subsystem */
|
|
static void watchdog_overflow_callback(struct perf_event *event, int nmi,
|
|
struct perf_sample_data *data,
|
|
struct pt_regs *regs)
|
|
{
|
|
/* Ensure the watchdog never gets throttled */
|
|
event->hw.interrupts = 0;
|
|
|
|
if (__this_cpu_read(watchdog_nmi_touch) == true) {
|
|
__this_cpu_write(watchdog_nmi_touch, false);
|
|
return;
|
|
}
|
|
|
|
/* check for a hardlockup
|
|
* This is done by making sure our timer interrupt
|
|
* is incrementing. The timer interrupt should have
|
|
* fired multiple times before we overflow'd. If it hasn't
|
|
* then this is a good indication the cpu is stuck
|
|
*/
|
|
if (is_hardlockup()) {
|
|
int this_cpu = smp_processor_id();
|
|
|
|
/* only print hardlockups once */
|
|
if (__this_cpu_read(hard_watchdog_warn) == true)
|
|
return;
|
|
|
|
if (hardlockup_panic)
|
|
panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu);
|
|
else
|
|
WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu);
|
|
|
|
__this_cpu_write(hard_watchdog_warn, true);
|
|
return;
|
|
}
|
|
|
|
__this_cpu_write(hard_watchdog_warn, false);
|
|
return;
|
|
}
|
|
static void watchdog_interrupt_count(void)
|
|
{
|
|
__this_cpu_inc(hrtimer_interrupts);
|
|
}
|
|
#else
|
|
static inline void watchdog_interrupt_count(void) { return; }
|
|
#endif /* CONFIG_HARDLOCKUP_DETECTOR */
|
|
|
|
/* 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;
|
|
|
|
/* 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(get_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();
|
|
}
|
|
__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)) {
|
|
/* only warn once */
|
|
if (__this_cpu_read(soft_watchdog_warn) == true)
|
|
return HRTIMER_RESTART;
|
|
|
|
printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
|
|
smp_processor_id(), duration,
|
|
current->comm, task_pid_nr(current));
|
|
print_modules();
|
|
print_irqtrace_events(current);
|
|
if (regs)
|
|
show_regs(regs);
|
|
else
|
|
dump_stack();
|
|
|
|
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;
|
|
}
|
|
|
|
|
|
/*
|
|
* The watchdog thread - touches the timestamp.
|
|
*/
|
|
static int watchdog(void *unused)
|
|
{
|
|
static struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
|
|
struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);
|
|
|
|
sched_setscheduler(current, SCHED_FIFO, ¶m);
|
|
|
|
/* initialize timestamp */
|
|
__touch_watchdog();
|
|
|
|
/* kick off the timer for the hardlockup detector */
|
|
/* done here because hrtimer_start can only pin to smp_processor_id() */
|
|
hrtimer_start(hrtimer, ns_to_ktime(get_sample_period()),
|
|
HRTIMER_MODE_REL_PINNED);
|
|
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
/*
|
|
* Run briefly once per second to reset the softlockup timestamp.
|
|
* If this gets delayed for more than 60 seconds then the
|
|
* debug-printout triggers in watchdog_timer_fn().
|
|
*/
|
|
while (!kthread_should_stop()) {
|
|
__touch_watchdog();
|
|
schedule();
|
|
|
|
if (kthread_should_stop())
|
|
break;
|
|
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
}
|
|
__set_current_state(TASK_RUNNING);
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
#ifdef CONFIG_HARDLOCKUP_DETECTOR
|
|
static int watchdog_nmi_enable(int cpu)
|
|
{
|
|
struct perf_event_attr *wd_attr;
|
|
struct perf_event *event = per_cpu(watchdog_ev, cpu);
|
|
|
|
/* is it already setup and enabled? */
|
|
if (event && event->state > PERF_EVENT_STATE_OFF)
|
|
goto out;
|
|
|
|
/* it is setup but not enabled */
|
|
if (event != NULL)
|
|
goto out_enable;
|
|
|
|
/* Try to register using hardware perf events */
|
|
wd_attr = &wd_hw_attr;
|
|
wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);
|
|
event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback);
|
|
if (!IS_ERR(event)) {
|
|
printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");
|
|
goto out_save;
|
|
}
|
|
|
|
|
|
/* vary the KERN level based on the returned errno */
|
|
if (PTR_ERR(event) == -EOPNOTSUPP)
|
|
printk(KERN_INFO "NMI watchdog disabled (cpu%i): not supported (no LAPIC?)\n", cpu);
|
|
else if (PTR_ERR(event) == -ENOENT)
|
|
printk(KERN_WARNING "NMI watchdog disabled (cpu%i): hardware events not enabled\n", cpu);
|
|
else
|
|
printk(KERN_ERR "NMI watchdog disabled (cpu%i): unable to create perf event: %ld\n", cpu, PTR_ERR(event));
|
|
return PTR_ERR(event);
|
|
|
|
/* success path */
|
|
out_save:
|
|
per_cpu(watchdog_ev, cpu) = event;
|
|
out_enable:
|
|
perf_event_enable(per_cpu(watchdog_ev, cpu));
|
|
out:
|
|
return 0;
|
|
}
|
|
|
|
static void watchdog_nmi_disable(int cpu)
|
|
{
|
|
struct perf_event *event = per_cpu(watchdog_ev, cpu);
|
|
|
|
if (event) {
|
|
perf_event_disable(event);
|
|
per_cpu(watchdog_ev, cpu) = NULL;
|
|
|
|
/* should be in cleanup, but blocks oprofile */
|
|
perf_event_release_kernel(event);
|
|
}
|
|
return;
|
|
}
|
|
#else
|
|
static int watchdog_nmi_enable(int cpu) { return 0; }
|
|
static void watchdog_nmi_disable(int cpu) { return; }
|
|
#endif /* CONFIG_HARDLOCKUP_DETECTOR */
|
|
|
|
/* prepare/enable/disable routines */
|
|
static int watchdog_prepare_cpu(int cpu)
|
|
{
|
|
struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
|
|
|
|
WARN_ON(per_cpu(softlockup_watchdog, cpu));
|
|
hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
|
|
hrtimer->function = watchdog_timer_fn;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int watchdog_enable(int cpu)
|
|
{
|
|
struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
|
|
int err = 0;
|
|
|
|
/* enable the perf event */
|
|
err = watchdog_nmi_enable(cpu);
|
|
|
|
/* Regardless of err above, fall through and start softlockup */
|
|
|
|
/* create the watchdog thread */
|
|
if (!p) {
|
|
p = kthread_create(watchdog, (void *)(unsigned long)cpu, "watchdog/%d", cpu);
|
|
if (IS_ERR(p)) {
|
|
printk(KERN_ERR "softlockup watchdog for %i failed\n", cpu);
|
|
if (!err) {
|
|
/* if hardlockup hasn't already set this */
|
|
err = PTR_ERR(p);
|
|
/* and disable the perf event */
|
|
watchdog_nmi_disable(cpu);
|
|
}
|
|
goto out;
|
|
}
|
|
kthread_bind(p, cpu);
|
|
per_cpu(watchdog_touch_ts, cpu) = 0;
|
|
per_cpu(softlockup_watchdog, cpu) = p;
|
|
wake_up_process(p);
|
|
}
|
|
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
static void watchdog_disable(int cpu)
|
|
{
|
|
struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
|
|
struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
|
|
|
|
/*
|
|
* cancel the timer first to stop incrementing the stats
|
|
* and waking up the kthread
|
|
*/
|
|
hrtimer_cancel(hrtimer);
|
|
|
|
/* disable the perf event */
|
|
watchdog_nmi_disable(cpu);
|
|
|
|
/* stop the watchdog thread */
|
|
if (p) {
|
|
per_cpu(softlockup_watchdog, cpu) = NULL;
|
|
kthread_stop(p);
|
|
}
|
|
}
|
|
|
|
static void watchdog_enable_all_cpus(void)
|
|
{
|
|
int cpu;
|
|
|
|
watchdog_enabled = 0;
|
|
|
|
for_each_online_cpu(cpu)
|
|
if (!watchdog_enable(cpu))
|
|
/* if any cpu succeeds, watchdog is considered
|
|
enabled for the system */
|
|
watchdog_enabled = 1;
|
|
|
|
if (!watchdog_enabled)
|
|
printk(KERN_ERR "watchdog: failed to be enabled on some cpus\n");
|
|
|
|
}
|
|
|
|
static void watchdog_disable_all_cpus(void)
|
|
{
|
|
int cpu;
|
|
|
|
for_each_online_cpu(cpu)
|
|
watchdog_disable(cpu);
|
|
|
|
/* if all watchdogs are disabled, then they are disabled for the system */
|
|
watchdog_enabled = 0;
|
|
}
|
|
|
|
|
|
/* sysctl functions */
|
|
#ifdef CONFIG_SYSCTL
|
|
/*
|
|
* proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh
|
|
*/
|
|
|
|
int proc_dowatchdog(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
int ret;
|
|
|
|
ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
|
|
if (ret || !write)
|
|
goto out;
|
|
|
|
if (watchdog_enabled && watchdog_thresh)
|
|
watchdog_enable_all_cpus();
|
|
else
|
|
watchdog_disable_all_cpus();
|
|
|
|
out:
|
|
return ret;
|
|
}
|
|
#endif /* CONFIG_SYSCTL */
|
|
|
|
|
|
/*
|
|
* Create/destroy watchdog threads as CPUs come and go:
|
|
*/
|
|
static int __cpuinit
|
|
cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
|
|
{
|
|
int hotcpu = (unsigned long)hcpu;
|
|
int err = 0;
|
|
|
|
switch (action) {
|
|
case CPU_UP_PREPARE:
|
|
case CPU_UP_PREPARE_FROZEN:
|
|
err = watchdog_prepare_cpu(hotcpu);
|
|
break;
|
|
case CPU_ONLINE:
|
|
case CPU_ONLINE_FROZEN:
|
|
if (watchdog_enabled)
|
|
err = watchdog_enable(hotcpu);
|
|
break;
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
case CPU_UP_CANCELED:
|
|
case CPU_UP_CANCELED_FROZEN:
|
|
watchdog_disable(hotcpu);
|
|
break;
|
|
case CPU_DEAD:
|
|
case CPU_DEAD_FROZEN:
|
|
watchdog_disable(hotcpu);
|
|
break;
|
|
#endif /* CONFIG_HOTPLUG_CPU */
|
|
}
|
|
|
|
/*
|
|
* hardlockup and softlockup are not important enough
|
|
* to block cpu bring up. Just always succeed and
|
|
* rely on printk output to flag problems.
|
|
*/
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
static struct notifier_block __cpuinitdata cpu_nfb = {
|
|
.notifier_call = cpu_callback
|
|
};
|
|
|
|
void __init lockup_detector_init(void)
|
|
{
|
|
void *cpu = (void *)(long)smp_processor_id();
|
|
int err;
|
|
|
|
err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
|
|
WARN_ON(notifier_to_errno(err));
|
|
|
|
cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
|
|
register_cpu_notifier(&cpu_nfb);
|
|
|
|
return;
|
|
}
|