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kernel/watchdog.c
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/* * Detect hard and soft lockups on a system * * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc. * |
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* 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 |
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* to those contributors as well. */ |
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#define pr_fmt(fmt) "NMI watchdog: " fmt |
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#include <linux/mm.h> #include <linux/cpu.h> #include <linux/nmi.h> #include <linux/init.h> |
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#include <linux/module.h> #include <linux/sysctl.h> |
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#include <linux/smpboot.h> |
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#include <linux/sched/rt.h> |
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#include <linux/tick.h> |
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#include <linux/workqueue.h> |
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#include <asm/irq_regs.h> |
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#include <linux/kvm_para.h> |
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#include <linux/perf_event.h> |
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#include <linux/kthread.h> |
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/* * The run state of the lockup detectors is controlled by the content of the * 'watchdog_enabled' variable. Each lockup detector has its dedicated bit - * bit 0 for the hard lockup detector and bit 1 for the soft lockup detector. * * 'watchdog_user_enabled', 'nmi_watchdog_enabled' and 'soft_watchdog_enabled' * are variables that are only used as an 'interface' between the parameters * in /proc/sys/kernel and the internal state bits in 'watchdog_enabled'. The * 'watchdog_thresh' variable is handled differently because its value is not * boolean, and the lockup detectors are 'suspended' while 'watchdog_thresh' * is equal zero. */ #define NMI_WATCHDOG_ENABLED_BIT 0 #define SOFT_WATCHDOG_ENABLED_BIT 1 #define NMI_WATCHDOG_ENABLED (1 << NMI_WATCHDOG_ENABLED_BIT) #define SOFT_WATCHDOG_ENABLED (1 << SOFT_WATCHDOG_ENABLED_BIT) |
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static DEFINE_MUTEX(watchdog_proc_mutex); |
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#ifdef CONFIG_HARDLOCKUP_DETECTOR static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED; #else static 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; |
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int __read_mostly watchdog_thresh = 10; |
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#ifdef CONFIG_SMP int __read_mostly sysctl_softlockup_all_cpu_backtrace; |
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int __read_mostly sysctl_hardlockup_all_cpu_backtrace; |
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#else #define sysctl_softlockup_all_cpu_backtrace 0 |
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#define sysctl_hardlockup_all_cpu_backtrace 0 |
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#endif |
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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) |
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/* * 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. */ |
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static int __read_mostly watchdog_running; |
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/* * 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; |
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static u64 __read_mostly sample_period; |
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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); |
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static DEFINE_PER_CPU(bool, soft_watchdog_warn); |
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static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt); |
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static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved); |
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#ifdef CONFIG_HARDLOCKUP_DETECTOR |
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static DEFINE_PER_CPU(bool, hard_watchdog_warn); static DEFINE_PER_CPU(bool, watchdog_nmi_touch); |
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static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); static DEFINE_PER_CPU(struct perf_event *, watchdog_ev); #endif |
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static unsigned long soft_lockup_nmi_warn; |
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/* boot commands */ /* * Should we panic when a soft-lockup or hard-lockup occurs: */ |
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#ifdef CONFIG_HARDLOCKUP_DETECTOR |
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unsigned int __read_mostly hardlockup_panic = |
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CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE; |
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static unsigned long hardlockup_allcpu_dumped; |
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/* * We may not want to enable hard lockup detection by default in all cases, * for example when running the kernel as a guest on a hypervisor. In these * cases this function can be called to disable hard lockup detection. This * function should only be executed once by the boot processor before the * kernel command line parameters are parsed, because otherwise it is not * possible to override this in hardlockup_panic_setup(). */ |
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void hardlockup_detector_disable(void) |
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{ |
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watchdog_enabled &= ~NMI_WATCHDOG_ENABLED; |
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} |
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static int __init hardlockup_panic_setup(char *str) { if (!strncmp(str, "panic", 5)) hardlockup_panic = 1; |
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else if (!strncmp(str, "nopanic", 7)) hardlockup_panic = 0; |
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else if (!strncmp(str, "0", 1)) |
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watchdog_enabled &= ~NMI_WATCHDOG_ENABLED; else if (!strncmp(str, "1", 1)) watchdog_enabled |= NMI_WATCHDOG_ENABLED; |
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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) { |
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watchdog_enabled = 0; |
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return 1; } __setup("nowatchdog", nowatchdog_setup); |
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static int __init nosoftlockup_setup(char *str) { |
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watchdog_enabled &= ~SOFT_WATCHDOG_ENABLED; |
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return 1; } __setup("nosoftlockup", nosoftlockup_setup); |
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#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; } __setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup); |
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static int __init hardlockup_all_cpu_backtrace_setup(char *str) { sysctl_hardlockup_all_cpu_backtrace = !!simple_strtol(str, NULL, 0); return 1; } __setup("hardlockup_all_cpu_backtrace=", hardlockup_all_cpu_backtrace_setup); |
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#endif |
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/* * 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. */ |
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static int get_softlockup_thresh(void) |
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{ 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. */ |
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static unsigned long get_timestamp(void) |
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{ |
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return running_clock() >> 30LL; /* 2^30 ~= 10^9 */ |
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} |
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static void set_sample_period(void) |
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{ /* |
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* convert watchdog_thresh from seconds to ns |
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* 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 |
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*/ |
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sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); |
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} /* Commands for resetting the watchdog */ static void __touch_watchdog(void) { |
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__this_cpu_write(watchdog_touch_ts, get_timestamp()); |
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} |
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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) |
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{ |
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/* * 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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} |
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void touch_softlockup_watchdog(void) { touch_softlockup_watchdog_sched(); |
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wq_watchdog_touch(raw_smp_processor_id()); |
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} |
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EXPORT_SYMBOL(touch_softlockup_watchdog); |
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void touch_all_softlockup_watchdogs(void) |
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{ 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 */ |
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for_each_watchdog_cpu(cpu) |
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per_cpu(watchdog_touch_ts, cpu) = 0; |
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wq_watchdog_touch(-1); |
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} |
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#ifdef CONFIG_HARDLOCKUP_DETECTOR |
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void touch_nmi_watchdog(void) { |
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/* * Using __raw here because some code paths have * preemption enabled. If preemption is enabled * then interrupts should be enabled too, in which * case we shouldn't have to worry about the watchdog * going off. */ |
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raw_cpu_write(watchdog_nmi_touch, true); |
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touch_softlockup_watchdog(); |
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} EXPORT_SYMBOL(touch_nmi_watchdog); |
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#endif |
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void touch_softlockup_watchdog_sync(void) { |
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__this_cpu_write(softlockup_touch_sync, true); __this_cpu_write(watchdog_touch_ts, 0); |
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} |
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#ifdef CONFIG_HARDLOCKUP_DETECTOR |
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/* watchdog detector functions */ |
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static bool is_hardlockup(void) |
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{ |
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unsigned long hrint = __this_cpu_read(hrtimer_interrupts); |
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if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) |
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return true; |
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__this_cpu_write(hrtimer_interrupts_saved, hrint); |
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return false; |
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} #endif |
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static int is_softlockup(unsigned long touch_ts) |
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{ |
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unsigned long now = get_timestamp(); |
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if ((watchdog_enabled & SOFT_WATCHDOG_ENABLED) && watchdog_thresh){ |
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/* Warn about unreasonable delays. */ if (time_after(now, touch_ts + get_softlockup_thresh())) return now - touch_ts; } |
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return 0; } |
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#ifdef CONFIG_HARDLOCKUP_DETECTOR |
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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 */ |
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static void watchdog_overflow_callback(struct perf_event *event, |
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struct perf_sample_data *data, struct pt_regs *regs) { |
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/* Ensure the watchdog never gets throttled */ event->hw.interrupts = 0; |
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if (__this_cpu_read(watchdog_nmi_touch) == true) { __this_cpu_write(watchdog_nmi_touch, false); |
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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 */ |
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if (is_hardlockup()) { int this_cpu = smp_processor_id(); |
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struct pt_regs *regs = get_irq_regs(); |
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/* only print hardlockups once */ |
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if (__this_cpu_read(hard_watchdog_warn) == true) |
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return; |
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pr_emerg("Watchdog detected hard LOCKUP on cpu %d", this_cpu); print_modules(); print_irqtrace_events(current); if (regs) show_regs(regs); |
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else |
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dump_stack(); /* * Perform all-CPU dump only once to avoid multiple hardlockups * generating interleaving traces */ if (sysctl_hardlockup_all_cpu_backtrace && !test_and_set_bit(0, &hardlockup_allcpu_dumped)) trigger_allbutself_cpu_backtrace(); if (hardlockup_panic) |
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nmi_panic(regs, "Hard LOCKUP"); |
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__this_cpu_write(hard_watchdog_warn, true); |
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return; } |
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__this_cpu_write(hard_watchdog_warn, false); |
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return; } |
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#endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
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static void watchdog_interrupt_count(void) { |
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__this_cpu_inc(hrtimer_interrupts); |
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} |
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static int watchdog_nmi_enable(unsigned int cpu); static void watchdog_nmi_disable(unsigned int cpu); |
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static int watchdog_enable_all_cpus(void); static void watchdog_disable_all_cpus(void); |
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/* watchdog kicker functions */ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) { |
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unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts); |
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struct pt_regs *regs = get_irq_regs(); int duration; |
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int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; |
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/* kick the hardlockup detector */ watchdog_interrupt_count(); /* kick the softlockup detector */ |
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wake_up_process(__this_cpu_read(softlockup_watchdog)); |
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/* .. and repeat */ |
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hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period)); |
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if (touch_ts == 0) { |
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if (unlikely(__this_cpu_read(softlockup_touch_sync))) { |
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/* * If the time stamp was touched atomically * make sure the scheduler tick is up to date. */ |
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__this_cpu_write(softlockup_touch_sync, false); |
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sched_clock_tick(); } |
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/* Clear the guest paused flag on watchdog reset */ kvm_check_and_clear_guest_paused(); |
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__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 */ |
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duration = is_softlockup(touch_ts); |
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if (unlikely(duration)) { |
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/* * 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; |
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/* only warn once */ |
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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(); } |
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return HRTIMER_RESTART; |
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} |
58687acba lockup_detector: ... |
437 |
|
ed235875e kernel/watchdog.c... |
438 439 440 441 442 443 444 445 446 447 |
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; } } |
656c3b79f kernel/watchdog.c... |
448 449 |
pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d] ", |
26e09c6ee lockup_detector: ... |
450 |
smp_processor_id(), duration, |
58687acba lockup_detector: ... |
451 |
current->comm, task_pid_nr(current)); |
b1a8de1f5 softlockup: make ... |
452 |
__this_cpu_write(softlockup_task_ptr_saved, current); |
58687acba lockup_detector: ... |
453 454 455 456 457 458 |
print_modules(); print_irqtrace_events(current); if (regs) show_regs(regs); else dump_stack(); |
ed235875e kernel/watchdog.c... |
459 460 461 462 463 464 465 466 467 468 |
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(); } |
69361eef9 panic: add TAINT_... |
469 |
add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK); |
58687acba lockup_detector: ... |
470 471 |
if (softlockup_panic) panic("softlockup: hung tasks"); |
909ea9646 core: Replace __g... |
472 |
__this_cpu_write(soft_watchdog_warn, true); |
58687acba lockup_detector: ... |
473 |
} else |
909ea9646 core: Replace __g... |
474 |
__this_cpu_write(soft_watchdog_warn, false); |
58687acba lockup_detector: ... |
475 476 477 |
return HRTIMER_RESTART; } |
bcd951cf1 watchdog: Use hot... |
478 479 480 |
static void watchdog_set_prio(unsigned int policy, unsigned int prio) { struct sched_param param = { .sched_priority = prio }; |
58687acba lockup_detector: ... |
481 |
|
bcd951cf1 watchdog: Use hot... |
482 483 484 485 |
sched_setscheduler(current, policy, ¶m); } static void watchdog_enable(unsigned int cpu) |
58687acba lockup_detector: ... |
486 |
{ |
f7f66b05a watchdog: Replace... |
487 |
struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); |
58687acba lockup_detector: ... |
488 |
|
3935e8950 watchdog: Fix dis... |
489 490 491 |
/* kick off the timer for the hardlockup detector */ hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); hrtimer->function = watchdog_timer_fn; |
bcd951cf1 watchdog: Use hot... |
492 493 |
/* Enable the perf event */ watchdog_nmi_enable(cpu); |
58687acba lockup_detector: ... |
494 |
|
58687acba lockup_detector: ... |
495 |
/* done here because hrtimer_start can only pin to smp_processor_id() */ |
0f34c4009 watchdog: store t... |
496 |
hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
58687acba lockup_detector: ... |
497 |
HRTIMER_MODE_REL_PINNED); |
bcd951cf1 watchdog: Use hot... |
498 499 500 501 |
/* initialize timestamp */ watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1); __touch_watchdog(); } |
58687acba lockup_detector: ... |
502 |
|
bcd951cf1 watchdog: Use hot... |
503 504 |
static void watchdog_disable(unsigned int cpu) { |
f7f66b05a watchdog: Replace... |
505 |
struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); |
58687acba lockup_detector: ... |
506 |
|
bcd951cf1 watchdog: Use hot... |
507 508 509 510 |
watchdog_set_prio(SCHED_NORMAL, 0); hrtimer_cancel(hrtimer); /* disable the perf event */ watchdog_nmi_disable(cpu); |
58687acba lockup_detector: ... |
511 |
} |
b8900bc02 watchdog: Registe... |
512 513 514 515 |
static void watchdog_cleanup(unsigned int cpu, bool online) { watchdog_disable(cpu); } |
bcd951cf1 watchdog: Use hot... |
516 517 518 519 520 521 522 523 524 |
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. * |
0f34c4009 watchdog: store t... |
525 |
* It only runs once every sample_period seconds (4 seconds by |
bcd951cf1 watchdog: Use hot... |
526 527 528 529 530 531 532 533 534 |
* 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(); |
bcfba4f4b watchdog: impleme... |
535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 |
/* * 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); |
bcd951cf1 watchdog: Use hot... |
550 |
} |
58687acba lockup_detector: ... |
551 |
|
23637d477 lockup_detector: ... |
552 |
#ifdef CONFIG_HARDLOCKUP_DETECTOR |
a70270468 watchdog: Quiet d... |
553 554 555 556 557 558 |
/* * 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; |
bcd951cf1 watchdog: Use hot... |
559 |
static int watchdog_nmi_enable(unsigned int cpu) |
58687acba lockup_detector: ... |
560 561 562 |
{ struct perf_event_attr *wd_attr; struct perf_event *event = per_cpu(watchdog_ev, cpu); |
195daf665 watchdog: enable ... |
563 564 565 |
/* nothing to do if the hard lockup detector is disabled */ if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED)) goto out; |
6e7458a6f kernel/watchdog.c... |
566 |
|
58687acba lockup_detector: ... |
567 568 569 570 571 572 573 |
/* 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; |
58687acba lockup_detector: ... |
574 |
wd_attr = &wd_hw_attr; |
4eec42f39 watchdog: Change ... |
575 |
wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); |
1880c4ae1 perf, x86: Add hw... |
576 577 |
/* Try to register using hardware perf events */ |
4dc0da869 perf: Add context... |
578 |
event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL); |
a70270468 watchdog: Quiet d... |
579 580 581 582 |
/* save cpu0 error for future comparision */ if (cpu == 0 && IS_ERR(event)) cpu0_err = PTR_ERR(event); |
58687acba lockup_detector: ... |
583 |
if (!IS_ERR(event)) { |
a70270468 watchdog: Quiet d... |
584 585 586 587 |
/* 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. "); |
58687acba lockup_detector: ... |
588 589 |
goto out_save; } |
bcfba4f4b watchdog: impleme... |
590 591 592 593 594 595 596 597 598 599 600 |
/* * Disable the hard lockup detector if _any_ CPU fails to set up * set up the hardware perf event. The watchdog() function checks * the NMI_WATCHDOG_ENABLED bit periodically. * * The barriers are for syncing up watchdog_enabled across all the * cpus, as clear_bit() does not use barriers. */ smp_mb__before_atomic(); clear_bit(NMI_WATCHDOG_ENABLED_BIT, &watchdog_enabled); smp_mb__after_atomic(); |
a70270468 watchdog: Quiet d... |
601 602 603 |
/* skip displaying the same error again */ if (cpu > 0 && (PTR_ERR(event) == cpu0_err)) return PTR_ERR(event); |
5651f7f47 watchdog, nmi: Lo... |
604 605 606 |
/* vary the KERN level based on the returned errno */ if (PTR_ERR(event) == -EOPNOTSUPP) |
4501980aa kernel/watchdog.c... |
607 608 |
pr_info("disabled (cpu%i): not supported (no LAPIC?) ", cpu); |
5651f7f47 watchdog, nmi: Lo... |
609 |
else if (PTR_ERR(event) == -ENOENT) |
656c3b79f kernel/watchdog.c... |
610 611 |
pr_warn("disabled (cpu%i): hardware events not enabled ", |
4501980aa kernel/watchdog.c... |
612 |
cpu); |
5651f7f47 watchdog, nmi: Lo... |
613 |
else |
4501980aa kernel/watchdog.c... |
614 615 616 |
pr_err("disabled (cpu%i): unable to create perf event: %ld ", cpu, PTR_ERR(event)); |
bcfba4f4b watchdog: impleme... |
617 618 619 |
pr_info("Shutting down hard lockup detector on all cpus "); |
eac243355 lockup_detector: ... |
620 |
return PTR_ERR(event); |
58687acba lockup_detector: ... |
621 622 623 624 625 626 627 628 629 |
/* success path */ out_save: per_cpu(watchdog_ev, cpu) = event; out_enable: perf_event_enable(per_cpu(watchdog_ev, cpu)); out: return 0; } |
bcd951cf1 watchdog: Use hot... |
630 |
static void watchdog_nmi_disable(unsigned int cpu) |
58687acba lockup_detector: ... |
631 632 633 634 635 636 637 638 639 640 |
{ 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); } |
df5771495 watchdog: Fix pri... |
641 642 643 644 |
if (cpu == 0) { /* watchdog_nmi_enable() expects this to be zero initially. */ cpu0_err = 0; } |
58687acba lockup_detector: ... |
645 |
} |
b3738d293 watchdog: Add wat... |
646 |
|
58687acba lockup_detector: ... |
647 |
#else |
bcd951cf1 watchdog: Use hot... |
648 649 |
static int watchdog_nmi_enable(unsigned int cpu) { return 0; } static void watchdog_nmi_disable(unsigned int cpu) { return; } |
23637d477 lockup_detector: ... |
650 |
#endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
58687acba lockup_detector: ... |
651 |
|
b8900bc02 watchdog: Registe... |
652 653 654 655 656 657 658 659 660 661 |
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, }; |
81a4beef9 watchdog: introdu... |
662 663 |
/* * park all watchdog threads that are specified in 'watchdog_cpumask' |
ee7fed540 watchdog: do not ... |
664 665 666 667 668 669 |
* * 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. |
a2a45b85e kernel/watchdog.c... |
670 671 672 |
* * This function may only be called in a context that is protected against * races with CPU hotplug - for example, via get_online_cpus(). |
81a4beef9 watchdog: introdu... |
673 674 675 676 |
*/ static int watchdog_park_threads(void) { int cpu, ret = 0; |
81a4beef9 watchdog: introdu... |
677 678 679 680 681 |
for_each_watchdog_cpu(cpu) { ret = kthread_park(per_cpu(softlockup_watchdog, cpu)); if (ret) break; } |
81a4beef9 watchdog: introdu... |
682 683 684 685 686 687 |
return ret; } /* * unpark all watchdog threads that are specified in 'watchdog_cpumask' |
a2a45b85e kernel/watchdog.c... |
688 689 690 |
* * This function may only be called in a context that is protected against * races with CPU hotplug - for example, via get_online_cpus(). |
81a4beef9 watchdog: introdu... |
691 692 693 694 |
*/ static void watchdog_unpark_threads(void) { int cpu; |
81a4beef9 watchdog: introdu... |
695 696 |
for_each_watchdog_cpu(cpu) kthread_unpark(per_cpu(softlockup_watchdog, cpu)); |
81a4beef9 watchdog: introdu... |
697 |
} |
8c073d27d watchdog: introdu... |
698 699 700 |
/* * Suspend the hard and soft lockup detector by parking the watchdog threads. */ |
ec6a90661 watchdog: rename ... |
701 |
int lockup_detector_suspend(void) |
8c073d27d watchdog: introdu... |
702 703 |
{ int ret = 0; |
ee89e71eb kernel/watchdog.c... |
704 |
get_online_cpus(); |
8c073d27d watchdog: introdu... |
705 706 707 708 709 710 |
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 |
ec6a90661 watchdog: rename ... |
711 |
* request is active (see related code in 'proc' handlers). |
8c073d27d watchdog: introdu... |
712 713 714 715 716 717 |
*/ if (watchdog_running && !watchdog_suspended) ret = watchdog_park_threads(); if (ret == 0) watchdog_suspended++; |
c993590c6 watchdog: impleme... |
718 719 720 721 722 723 |
else { watchdog_disable_all_cpus(); pr_err("Failed to suspend lockup detectors, disabled "); watchdog_enabled = 0; } |
8c073d27d watchdog: introdu... |
724 725 726 727 728 729 730 731 732 |
mutex_unlock(&watchdog_proc_mutex); return ret; } /* * Resume the hard and soft lockup detector by unparking the watchdog threads. */ |
ec6a90661 watchdog: rename ... |
733 |
void lockup_detector_resume(void) |
8c073d27d watchdog: introdu... |
734 735 736 737 738 739 740 741 742 743 744 745 |
{ 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); |
ee89e71eb kernel/watchdog.c... |
746 |
put_online_cpus(); |
8c073d27d watchdog: introdu... |
747 |
} |
b43cb43cb watchdog: impleme... |
748 |
static int update_watchdog_all_cpus(void) |
9809b18fc watchdog: update ... |
749 |
{ |
b43cb43cb watchdog: impleme... |
750 751 752 753 754 |
int ret; ret = watchdog_park_threads(); if (ret) return ret; |
d4bdd0b21 watchdog: use par... |
755 |
watchdog_unpark_threads(); |
b43cb43cb watchdog: impleme... |
756 757 |
return 0; |
9809b18fc watchdog: update ... |
758 |
} |
b2f57c3a0 watchdog: clean u... |
759 |
static int watchdog_enable_all_cpus(void) |
58687acba lockup_detector: ... |
760 |
{ |
b8900bc02 watchdog: Registe... |
761 |
int err = 0; |
58687acba lockup_detector: ... |
762 |
|
3c00ea82c watchdog: Rename ... |
763 |
if (!watchdog_running) { |
230ec9390 smpboot: allow pa... |
764 765 |
err = smpboot_register_percpu_thread_cpumask(&watchdog_threads, &watchdog_cpumask); |
b8900bc02 watchdog: Registe... |
766 767 768 |
if (err) pr_err("Failed to create watchdog threads, disabled "); |
230ec9390 smpboot: allow pa... |
769 |
else |
3c00ea82c watchdog: Rename ... |
770 |
watchdog_running = 1; |
b2f57c3a0 watchdog: clean u... |
771 772 773 774 775 |
} else { /* * Enable/disable the lockup detectors or * change the sample period 'on the fly'. */ |
b43cb43cb watchdog: impleme... |
776 777 778 779 780 781 782 |
err = update_watchdog_all_cpus(); if (err) { watchdog_disable_all_cpus(); pr_err("Failed to update lockup detectors, disabled "); } |
bcd951cf1 watchdog: Use hot... |
783 |
} |
b8900bc02 watchdog: Registe... |
784 |
|
b43cb43cb watchdog: impleme... |
785 786 |
if (err) watchdog_enabled = 0; |
b8900bc02 watchdog: Registe... |
787 |
return err; |
58687acba lockup_detector: ... |
788 789 790 791 |
} static void watchdog_disable_all_cpus(void) { |
3c00ea82c watchdog: Rename ... |
792 793 |
if (watchdog_running) { watchdog_running = 0; |
b8900bc02 watchdog: Registe... |
794 |
smpboot_unregister_percpu_thread(&watchdog_threads); |
bcd951cf1 watchdog: Use hot... |
795 |
} |
58687acba lockup_detector: ... |
796 |
} |
58cf690a0 watchdog: move wa... |
797 |
#ifdef CONFIG_SYSCTL |
58687acba lockup_detector: ... |
798 |
/* |
a0c9cbb93 watchdog: introdu... |
799 800 801 802 803 804 805 806 807 808 809 810 811 812 |
* 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) |
b2f57c3a0 watchdog: clean u... |
813 |
err = watchdog_enable_all_cpus(); |
a0c9cbb93 watchdog: introdu... |
814 815 816 817 818 819 820 821 |
else watchdog_disable_all_cpus(); return err; } /* |
ef246a216 watchdog: introdu... |
822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 |
* 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; |
8614ddef8 kernel/watchdog.c... |
838 |
get_online_cpus(); |
ef246a216 watchdog: introdu... |
839 |
mutex_lock(&watchdog_proc_mutex); |
8c073d27d watchdog: introdu... |
840 841 842 843 844 |
if (watchdog_suspended) { /* no parameter changes allowed while watchdog is suspended */ err = -EAGAIN; goto out; } |
ef246a216 watchdog: introdu... |
845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 |
/* * 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); /* |
b43cb43cb watchdog: impleme... |
878 879 880 881 882 |
* 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. |
ef246a216 watchdog: introdu... |
883 |
*/ |
a1ee1932a watchdog: don't r... |
884 885 |
if (old == new) goto out; |
ef246a216 watchdog: introdu... |
886 |
err = proc_watchdog_update(); |
ef246a216 watchdog: introdu... |
887 888 889 |
} out: mutex_unlock(&watchdog_proc_mutex); |
8614ddef8 kernel/watchdog.c... |
890 |
put_online_cpus(); |
ef246a216 watchdog: introdu... |
891 892 893 894 |
return err; } /* |
83a80a390 watchdog: introdu... |
895 896 897 898 899 900 901 902 903 904 905 |
* /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); } /* * /proc/sys/kernel/nmi_watchdog |
58687acba lockup_detector: ... |
906 |
*/ |
83a80a390 watchdog: introdu... |
907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 |
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); } /* * /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); } |
58687acba lockup_detector: ... |
923 |
|
83a80a390 watchdog: introdu... |
924 925 926 927 928 |
/* * /proc/sys/kernel/watchdog_thresh */ int proc_watchdog_thresh(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) |
58687acba lockup_detector: ... |
929 |
{ |
a1ee1932a watchdog: don't r... |
930 |
int err, old, new; |
58687acba lockup_detector: ... |
931 |
|
8614ddef8 kernel/watchdog.c... |
932 |
get_online_cpus(); |
359e6fab6 watchdog: update ... |
933 |
mutex_lock(&watchdog_proc_mutex); |
bcd951cf1 watchdog: Use hot... |
934 |
|
8c073d27d watchdog: introdu... |
935 936 937 938 939 |
if (watchdog_suspended) { /* no parameter changes allowed while watchdog is suspended */ err = -EAGAIN; goto out; } |
83a80a390 watchdog: introdu... |
940 |
old = ACCESS_ONCE(watchdog_thresh); |
b8900bc02 watchdog: Registe... |
941 |
err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
83a80a390 watchdog: introdu... |
942 |
|
b8900bc02 watchdog: Registe... |
943 |
if (err || !write) |
359e6fab6 watchdog: update ... |
944 |
goto out; |
e04ab2bc4 watchdog: Only di... |
945 |
|
b66a2356d watchdog: Add com... |
946 |
/* |
d283c640c watchdog: fix err... |
947 |
* Update the sample period. Restore on failure. |
b66a2356d watchdog: Add com... |
948 |
*/ |
a1ee1932a watchdog: don't r... |
949 950 951 |
new = ACCESS_ONCE(watchdog_thresh); if (old == new) goto out; |
83a80a390 watchdog: introdu... |
952 953 |
set_sample_period(); err = proc_watchdog_update(); |
d283c640c watchdog: fix err... |
954 |
if (err) { |
83a80a390 watchdog: introdu... |
955 |
watchdog_thresh = old; |
d283c640c watchdog: fix err... |
956 957 |
set_sample_period(); } |
359e6fab6 watchdog: update ... |
958 959 |
out: mutex_unlock(&watchdog_proc_mutex); |
8614ddef8 kernel/watchdog.c... |
960 |
put_online_cpus(); |
b8900bc02 watchdog: Registe... |
961 |
return err; |
58687acba lockup_detector: ... |
962 |
} |
fe4ba3c34 watchdog: add wat... |
963 964 965 966 967 968 969 970 971 972 973 |
/* * 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; |
8614ddef8 kernel/watchdog.c... |
974 |
get_online_cpus(); |
fe4ba3c34 watchdog: add wat... |
975 |
mutex_lock(&watchdog_proc_mutex); |
8c073d27d watchdog: introdu... |
976 977 978 979 980 981 |
if (watchdog_suspended) { /* no parameter changes allowed while watchdog is suspended */ err = -EAGAIN; goto out; } |
fe4ba3c34 watchdog: add wat... |
982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 |
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 "); } } |
8c073d27d watchdog: introdu... |
1000 |
out: |
fe4ba3c34 watchdog: add wat... |
1001 |
mutex_unlock(&watchdog_proc_mutex); |
8614ddef8 kernel/watchdog.c... |
1002 |
put_online_cpus(); |
fe4ba3c34 watchdog: add wat... |
1003 1004 |
return err; } |
58687acba lockup_detector: ... |
1005 |
#endif /* CONFIG_SYSCTL */ |
004417a6d perf, arch: Clean... |
1006 |
void __init lockup_detector_init(void) |
58687acba lockup_detector: ... |
1007 |
{ |
0f34c4009 watchdog: store t... |
1008 |
set_sample_period(); |
b8900bc02 watchdog: Registe... |
1009 |
|
fe4ba3c34 watchdog: add wat... |
1010 1011 |
#ifdef CONFIG_NO_HZ_FULL if (tick_nohz_full_enabled()) { |
314b08ff5 watchdog: simplif... |
1012 1013 1014 |
pr_info("Disabling watchdog on nohz_full cores by default "); cpumask_copy(&watchdog_cpumask, housekeeping_mask); |
fe4ba3c34 watchdog: add wat... |
1015 1016 1017 1018 1019 |
} else cpumask_copy(&watchdog_cpumask, cpu_possible_mask); #else cpumask_copy(&watchdog_cpumask, cpu_possible_mask); #endif |
195daf665 watchdog: enable ... |
1020 |
if (watchdog_enabled) |
b2f57c3a0 watchdog: clean u... |
1021 |
watchdog_enable_all_cpus(); |
58687acba lockup_detector: ... |
1022 |
} |