/* * 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/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 <linux/smpboot.h>#include <linux/sched/rt.h> #include <asm/irq_regs.h>#include <linux/kvm_para.h>#include <linux/perf_event.h> int watchdog_user_enabled = 1;int __read_mostly watchdog_thresh = 10;static int __read_mostly watchdog_running;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);#ifdef CONFIG_HARDLOCKUP_DETECTORstatic DEFINE_PER_CPU(bool, hard_watchdog_warn);static DEFINE_PER_CPU(bool, watchdog_nmi_touch);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_DETECTORstatic 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_user_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_user_enabled = 0; return 1;}__setup("nowatchdog", nowatchdog_setup); /* deprecated */static int __init nosoftlockup_setup(char *str){ watchdog_user_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(void){ 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(void){ return local_clock() >> 30LL; /* 2^30 ~= 10^9 */} 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);} /* Commands for resetting the watchdog */static void __touch_watchdog(void){ __this_cpu_write(watchdog_touch_ts, get_timestamp());} 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_DETECTORvoid touch_nmi_watchdog(void){ if (watchdog_user_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(); /* 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, 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;}#endif /* CONFIG_HARDLOCKUP_DETECTOR */ static void watchdog_interrupt_count(void){ __this_cpu_inc(hrtimer_interrupts);} static int watchdog_nmi_enable(unsigned int cpu);static void watchdog_nmi_disable(unsigned int cpu); /* 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(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) return HRTIMER_RESTART; printk(KERN_EMERG "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;} static void watchdog_set_prio(unsigned int policy, unsigned int prio){ struct sched_param param = { .sched_priority = prio }; sched_setscheduler(current, policy, ¶m);} static void watchdog_enable(unsigned int cpu){ struct hrtimer *hrtimer = &__raw_get_cpu_var(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();} static void watchdog_disable(unsigned int cpu){ struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); watchdog_set_prio(SCHED_NORMAL, 0); hrtimer_cancel(hrtimer); /* disable the perf event */ watchdog_nmi_disable(cpu);} static void watchdog_cleanup(unsigned int cpu, bool online){ watchdog_disable(cpu);} static int watchdog_should_run(unsigned int cpu){ return __this_cpu_read(hrtimer_interrupts) != __this_cpu_read(soft_lockup_hrtimer_cnt);} /* * 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();} #ifdef CONFIG_HARDLOCKUP_DETECTOR/* * People like the simple clean cpu node info on boot. * Reduce the watchdog noise by only printing messages * that are different from what cpu0 displayed. */static unsigned long cpu0_err; static int watchdog_nmi_enable(unsigned 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; wd_attr = &wd_hw_attr; wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); /* Try to register using hardware perf events */ event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL); /* save cpu0 error for future comparision */ if (cpu == 0 && IS_ERR(event)) cpu0_err = PTR_ERR(event); if (!IS_ERR(event)) { /* only print for cpu0 or different than cpu0 */ if (cpu == 0 || cpu0_err) pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n"); goto out_save; } /* skip displaying the same error again */ if (cpu > 0 && (PTR_ERR(event) == cpu0_err)) return PTR_ERR(event); /* vary the KERN level based on the returned errno */ if (PTR_ERR(event) == -EOPNOTSUPP) pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu); else if (PTR_ERR(event) == -ENOENT) pr_warning("disabled (cpu%i): hardware events not enabled\n", cpu); else pr_err("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(unsigned 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;}#elsestatic int watchdog_nmi_enable(unsigned int cpu) { return 0; }static void watchdog_nmi_disable(unsigned int cpu) { return; }#endif /* CONFIG_HARDLOCKUP_DETECTOR */ 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,}; static void restart_watchdog_hrtimer(void *info){ struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); int ret; /* * No need to cancel and restart hrtimer if it is currently executing * because it will reprogram itself with the new period now. * We should never see it unqueued here because we are running per-cpu * with interrupts disabled. */ ret = hrtimer_try_to_cancel(hrtimer);Lines 1–500 of 608. 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/* * 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/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 <linux/smpboot.h> #include <linux/sched/rt.h> #include <asm/irq_regs.h> #include <linux/kvm_para.h> #include <linux/perf_event.h> int watchdog_user_enabled = 1; int __read_mostly watchdog_thresh = 10; static int __read_mostly watchdog_running; 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); #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_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_user_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_user_enabled = 0; return 1; } __setup("nowatchdog", nowatchdog_setup); /* deprecated */ static int __init nosoftlockup_setup(char *str) { watchdog_user_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(void) { 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(void) { return local_clock() >> 30LL; /* 2^30 ~= 10^9 */ } 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); } /* Commands for resetting the watchdog */ static void __touch_watchdog(void) { __this_cpu_write(watchdog_touch_ts, get_timestamp()); } 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_user_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(); /* 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, 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; } #endif /* CONFIG_HARDLOCKUP_DETECTOR */ static void watchdog_interrupt_count(void) { __this_cpu_inc(hrtimer_interrupts); } static int watchdog_nmi_enable(unsigned int cpu); static void watchdog_nmi_disable(unsigned int cpu); /* 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(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) return HRTIMER_RESTART; printk(KERN_EMERG "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; } static void watchdog_set_prio(unsigned int policy, unsigned int prio) { struct sched_param param = { .sched_priority = prio }; sched_setscheduler(current, policy, ¶m); } static void watchdog_enable(unsigned int cpu) { struct hrtimer *hrtimer = &__raw_get_cpu_var(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(); } static void watchdog_disable(unsigned int cpu) { struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); watchdog_set_prio(SCHED_NORMAL, 0); hrtimer_cancel(hrtimer); /* disable the perf event */ watchdog_nmi_disable(cpu); } static void watchdog_cleanup(unsigned int cpu, bool online) { watchdog_disable(cpu); } static int watchdog_should_run(unsigned int cpu) { return __this_cpu_read(hrtimer_interrupts) != __this_cpu_read(soft_lockup_hrtimer_cnt); } /* * 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(); } #ifdef CONFIG_HARDLOCKUP_DETECTOR /* * People like the simple clean cpu node info on boot. * Reduce the watchdog noise by only printing messages * that are different from what cpu0 displayed. */ static unsigned long cpu0_err; static int watchdog_nmi_enable(unsigned 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; wd_attr = &wd_hw_attr; wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); /* Try to register using hardware perf events */ event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL); /* save cpu0 error for future comparision */ if (cpu == 0 && IS_ERR(event)) cpu0_err = PTR_ERR(event); if (!IS_ERR(event)) { /* only print for cpu0 or different than cpu0 */ if (cpu == 0 || cpu0_err) pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n"); goto out_save; } /* skip displaying the same error again */ if (cpu > 0 && (PTR_ERR(event) == cpu0_err)) return PTR_ERR(event); /* vary the KERN level based on the returned errno */ if (PTR_ERR(event) == -EOPNOTSUPP) pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu); else if (PTR_ERR(event) == -ENOENT) pr_warning("disabled (cpu%i): hardware events not enabled\n", cpu); else pr_err("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(unsigned 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(unsigned int cpu) { return 0; } static void watchdog_nmi_disable(unsigned int cpu) { return; } #endif /* CONFIG_HARDLOCKUP_DETECTOR */ 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, }; static void restart_watchdog_hrtimer(void *info) { struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); int ret; /* * No need to cancel and restart hrtimer if it is currently executing * because it will reprogram itself with the new period now. * We should never see it unqueued here because we are running per-cpu * with interrupts disabled. */ ret = hrtimer_try_to_cancel(hrtimer);