| /* |
| * 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; |
| int __read_mostly softlockup_thresh = 60; |
| |
| 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 |
| |
| static int no_watchdog; |
| |
| |
| /* boot commands */ |
| /* |
| * Should we panic when a soft-lockup or hard-lockup occurs: |
| */ |
| #ifdef CONFIG_HARDLOCKUP_DETECTOR |
| static int hardlockup_panic; |
| |
| static int __init hardlockup_panic_setup(char *str) |
| { |
| if (!strncmp(str, "panic", 5)) |
| hardlockup_panic = 1; |
| 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) |
| { |
| no_watchdog = 1; |
| return 1; |
| } |
| __setup("nowatchdog", nowatchdog_setup); |
| |
| /* deprecated */ |
| static int __init nosoftlockup_setup(char *str) |
| { |
| no_watchdog = 1; |
| return 1; |
| } |
| __setup("nosoftlockup", nosoftlockup_setup); |
| /* */ |
| |
| |
| /* |
| * 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 softlockup_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 softlockup_thresh / 5 * NSEC_PER_SEC; |
| } |
| |
| /* Commands for resetting the watchdog */ |
| static void __touch_watchdog(void) |
| { |
| int this_cpu = smp_processor_id(); |
| |
| __get_cpu_var(watchdog_touch_ts) = get_timestamp(this_cpu); |
| } |
| |
| void touch_softlockup_watchdog(void) |
| { |
| __raw_get_cpu_var(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 = __get_cpu_var(hrtimer_interrupts); |
| |
| if (__get_cpu_var(hrtimer_interrupts_saved) == hrint) |
| return 1; |
| |
| __get_cpu_var(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 + 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 (__get_cpu_var(watchdog_nmi_touch) == true) { |
| __get_cpu_var(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 (__get_cpu_var(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); |
| |
| __get_cpu_var(hard_watchdog_warn) = true; |
| return; |
| } |
| |
| __get_cpu_var(hard_watchdog_warn) = false; |
| return; |
| } |
| static void watchdog_interrupt_count(void) |
| { |
| __get_cpu_var(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 = __get_cpu_var(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(__get_cpu_var(softlockup_watchdog)); |
| |
| /* .. and repeat */ |
| hrtimer_forward_now(hrtimer, ns_to_ktime(get_sample_period())); |
| |
| if (touch_ts == 0) { |
| if (unlikely(__get_cpu_var(softlockup_touch_sync))) { |
| /* |
| * If the time stamp was touched atomically |
| * make sure the scheduler tick is up to date. |
| */ |
| __get_cpu_var(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 (__get_cpu_var(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"); |
| __get_cpu_var(soft_watchdog_warn) = true; |
| } else |
| __get_cpu_var(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(); |
| 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; |
| } |
| |
| printk(KERN_ERR "NMI watchdog failed to create perf event on cpu%i: %p\n", cpu, 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; |
| |
| /* enable the perf event */ |
| err = watchdog_nmi_enable(cpu); |
| if (err) |
| return err; |
| |
| /* 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); |
| return PTR_ERR(p); |
| } |
| kthread_bind(p, cpu); |
| per_cpu(watchdog_touch_ts, cpu) = 0; |
| per_cpu(softlockup_watchdog, cpu) = p; |
| wake_up_process(p); |
| } |
| |
| /* if any cpu succeeds, watchdog is considered enabled for the system */ |
| watchdog_enabled = 1; |
| |
| return 0; |
| } |
| |
| 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; |
| int result = 0; |
| |
| for_each_online_cpu(cpu) |
| result += watchdog_enable(cpu); |
| |
| if (result) |
| printk(KERN_ERR "watchdog: failed to be enabled on some cpus\n"); |
| |
| } |
| |
| static void watchdog_disable_all_cpus(void) |
| { |
| int cpu; |
| |
| if (no_watchdog) |
| return; |
| |
| 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 |
| */ |
| |
| int proc_dowatchdog_enabled(struct ctl_table *table, int write, |
| void __user *buffer, size_t *length, loff_t *ppos) |
| { |
| proc_dointvec(table, write, buffer, length, ppos); |
| |
| if (watchdog_enabled) |
| watchdog_enable_all_cpus(); |
| else |
| watchdog_disable_all_cpus(); |
| return 0; |
| } |
| |
| int proc_dowatchdog_thresh(struct ctl_table *table, int write, |
| void __user *buffer, |
| size_t *lenp, loff_t *ppos) |
| { |
| return proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
| } |
| #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: |
| 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 */ |
| } |
| return notifier_from_errno(err); |
| } |
| |
| static struct notifier_block __cpuinitdata cpu_nfb = { |
| .notifier_call = cpu_callback |
| }; |
| |
| static int __init spawn_watchdog_task(void) |
| { |
| void *cpu = (void *)(long)smp_processor_id(); |
| int err; |
| |
| if (no_watchdog) |
| return 0; |
| |
| 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 0; |
| } |
| early_initcall(spawn_watchdog_task); |