1 files changed, 570 insertions, 0 deletions

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
new file mode 100644
index 000000000000..0d53c8e853b1
--- /dev/null
+++ b/kernel/watchdog.c
@@ -0,0 +1,570 @@
+/*
+ * 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 __read_mostly did_panic;
+static int __initdata 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)
+{
+        __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)
+{
+        __get_cpu_var(watchdog_nmi_touch) = 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;
+}
+
+static int
+watchdog_panic(struct notifier_block *this, unsigned long event, void *ptr)
+{
+        did_panic = 1;
+
+        return NOTIFY_DONE;
+}
+
+static struct notifier_block panic_block = {
+        .notifier_call = watchdog_panic,
+};
+
+#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 */
+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)
+{
+        struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
+        struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);
+
+        sched_setscheduler(current, SCHED_FIFO, &param);
+
+        /* 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, -1, 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 -1;
+
+        /* 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);
+
+        /* enable the perf event */
+        if (watchdog_nmi_enable(cpu) != 0)
+                return -1;
+
+        /* 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 -1;
+                }
+                kthread_bind(p, cpu);
+                per_cpu(watchdog_touch_ts, cpu) = 0;
+                per_cpu(softlockup_watchdog, cpu) = p;
+                wake_up_process(p);
+        }
+
+        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);
+        }
+
+        /* if any cpu succeeds, watchdog is considered enabled for the system */
+        watchdog_enabled = 1;
+}
+
+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;
+
+        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;
+
+        switch (action) {
+        case CPU_UP_PREPARE:
+        case CPU_UP_PREPARE_FROZEN:
+                if (watchdog_prepare_cpu(hotcpu))
+                        return NOTIFY_BAD;
+                break;
+        case CPU_ONLINE:
+        case CPU_ONLINE_FROZEN:
+                if (watchdog_enable(hotcpu))
+                        return NOTIFY_BAD;
+                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 NOTIFY_OK;
+}
+
+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(err == NOTIFY_BAD);
+
+        cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
+        register_cpu_notifier(&cpu_nfb);
+
+        atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
+
+        return 0;
+}
+early_initcall(spawn_watchdog_task);