watchdog: Use hotplug thread infrastructure
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung@kernel.org> Link: http://lkml.kernel.org/r/20120716103948.563736676@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Thomas Gleixner
parent
3e339b5dae
commit
bcd951cf10
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@ -22,6 +22,7 @@
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#include <linux/notifier.h>
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#include <linux/module.h>
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#include <linux/sysctl.h>
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#include <linux/smpboot.h>
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#include <asm/irq_regs.h>
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#include <linux/kvm_para.h>
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@ -29,16 +30,18 @@
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int watchdog_enabled = 1;
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int __read_mostly watchdog_thresh = 10;
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static int __read_mostly watchdog_disabled;
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static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
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static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
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static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer);
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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);
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static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt);
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#ifdef CONFIG_HARDLOCKUP_DETECTOR
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static DEFINE_PER_CPU(bool, hard_watchdog_warn);
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static DEFINE_PER_CPU(bool, watchdog_nmi_touch);
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static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);
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static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);
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static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
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#endif
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@ -248,13 +251,15 @@ static void watchdog_overflow_callback(struct perf_event *event,
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__this_cpu_write(hard_watchdog_warn, false);
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return;
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}
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#endif /* CONFIG_HARDLOCKUP_DETECTOR */
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static void watchdog_interrupt_count(void)
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{
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__this_cpu_inc(hrtimer_interrupts);
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}
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#else
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static inline void watchdog_interrupt_count(void) { return; }
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#endif /* CONFIG_HARDLOCKUP_DETECTOR */
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static int watchdog_nmi_enable(unsigned int cpu);
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static void watchdog_nmi_disable(unsigned int cpu);
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/* watchdog kicker functions */
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static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
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@ -327,49 +332,68 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
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return HRTIMER_RESTART;
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}
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/*
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* The watchdog thread - touches the timestamp.
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*/
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static int watchdog(void *unused)
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static void watchdog_set_prio(unsigned int policy, unsigned int prio)
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{
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struct sched_param param = { .sched_priority = prio };
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sched_setscheduler(current, policy, ¶m);
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}
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static void watchdog_enable(unsigned int cpu)
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{
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struct sched_param param = { .sched_priority = 0 };
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struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);
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/* initialize timestamp */
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__touch_watchdog();
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if (!watchdog_enabled) {
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kthread_park(current);
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return;
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}
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/* Enable the perf event */
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watchdog_nmi_enable(cpu);
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/* kick off the timer for the hardlockup detector */
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hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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hrtimer->function = watchdog_timer_fn;
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/* done here because hrtimer_start can only pin to smp_processor_id() */
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hrtimer_start(hrtimer, ns_to_ktime(get_sample_period()),
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HRTIMER_MODE_REL_PINNED);
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set_current_state(TASK_INTERRUPTIBLE);
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/*
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* Run briefly (kicked by the hrtimer callback function) once every
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* get_sample_period() seconds (4 seconds by default) to reset the
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* softlockup timestamp. If this gets delayed for more than
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* 2*watchdog_thresh seconds then the debug-printout triggers in
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* watchdog_timer_fn().
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*/
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while (!kthread_should_stop()) {
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__touch_watchdog();
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schedule();
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if (kthread_should_stop())
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break;
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set_current_state(TASK_INTERRUPTIBLE);
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}
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/*
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* Drop the policy/priority elevation during thread exit to avoid a
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* scheduling latency spike.
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*/
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__set_current_state(TASK_RUNNING);
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sched_setscheduler(current, SCHED_NORMAL, ¶m);
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return 0;
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/* initialize timestamp */
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watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1);
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__touch_watchdog();
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}
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static void watchdog_disable(unsigned int cpu)
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{
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struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);
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watchdog_set_prio(SCHED_NORMAL, 0);
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hrtimer_cancel(hrtimer);
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/* disable the perf event */
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watchdog_nmi_disable(cpu);
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}
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static int watchdog_should_run(unsigned int cpu)
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{
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return __this_cpu_read(hrtimer_interrupts) !=
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__this_cpu_read(soft_lockup_hrtimer_cnt);
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}
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/*
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* The watchdog thread function - touches the timestamp.
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*
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* It only runs once every get_sample_period() seconds (4 seconds by
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* default) to reset the softlockup timestamp. If this gets delayed
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* for more than 2*watchdog_thresh seconds then the debug-printout
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* triggers in watchdog_timer_fn().
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*/
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static void watchdog(unsigned int cpu)
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{
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__this_cpu_write(soft_lockup_hrtimer_cnt,
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__this_cpu_read(hrtimer_interrupts));
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__touch_watchdog();
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}
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#ifdef CONFIG_HARDLOCKUP_DETECTOR
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/*
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@ -379,7 +403,7 @@ static int watchdog(void *unused)
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*/
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static unsigned long cpu0_err;
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static int watchdog_nmi_enable(int cpu)
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static int watchdog_nmi_enable(unsigned int cpu)
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{
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struct perf_event_attr *wd_attr;
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struct perf_event *event = per_cpu(watchdog_ev, cpu);
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@ -433,7 +457,7 @@ out:
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return 0;
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}
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static void watchdog_nmi_disable(int cpu)
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static void watchdog_nmi_disable(unsigned int cpu)
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{
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struct perf_event *event = per_cpu(watchdog_ev, cpu);
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@ -447,107 +471,35 @@ static void watchdog_nmi_disable(int cpu)
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return;
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}
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#else
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static int watchdog_nmi_enable(int cpu) { return 0; }
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static void watchdog_nmi_disable(int cpu) { return; }
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static int watchdog_nmi_enable(unsigned int cpu) { return 0; }
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static void watchdog_nmi_disable(unsigned int cpu) { return; }
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#endif /* CONFIG_HARDLOCKUP_DETECTOR */
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/* prepare/enable/disable routines */
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static void watchdog_prepare_cpu(int cpu)
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{
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struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
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WARN_ON(per_cpu(softlockup_watchdog, cpu));
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hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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hrtimer->function = watchdog_timer_fn;
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}
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static int watchdog_enable(int cpu)
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{
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struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
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int err = 0;
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/* enable the perf event */
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err = watchdog_nmi_enable(cpu);
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/* Regardless of err above, fall through and start softlockup */
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/* create the watchdog thread */
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if (!p) {
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struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
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p = kthread_create_on_node(watchdog, NULL, cpu_to_node(cpu), "watchdog/%d", cpu);
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if (IS_ERR(p)) {
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pr_err("softlockup watchdog for %i failed\n", cpu);
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if (!err) {
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/* if hardlockup hasn't already set this */
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err = PTR_ERR(p);
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/* and disable the perf event */
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watchdog_nmi_disable(cpu);
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}
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goto out;
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}
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sched_setscheduler(p, SCHED_FIFO, ¶m);
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kthread_bind(p, cpu);
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per_cpu(watchdog_touch_ts, cpu) = 0;
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per_cpu(softlockup_watchdog, cpu) = p;
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wake_up_process(p);
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}
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out:
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return err;
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}
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static void watchdog_disable(int cpu)
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{
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struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
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struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
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/*
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* cancel the timer first to stop incrementing the stats
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* and waking up the kthread
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*/
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hrtimer_cancel(hrtimer);
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/* disable the perf event */
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watchdog_nmi_disable(cpu);
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/* stop the watchdog thread */
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if (p) {
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per_cpu(softlockup_watchdog, cpu) = NULL;
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kthread_stop(p);
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}
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}
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/* sysctl functions */
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#ifdef CONFIG_SYSCTL
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static void watchdog_enable_all_cpus(void)
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{
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int cpu;
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watchdog_enabled = 0;
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for_each_online_cpu(cpu)
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if (!watchdog_enable(cpu))
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/* if any cpu succeeds, watchdog is considered
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enabled for the system */
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watchdog_enabled = 1;
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if (!watchdog_enabled)
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pr_err("failed to be enabled on some cpus\n");
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unsigned int cpu;
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if (watchdog_disabled) {
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watchdog_disabled = 0;
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for_each_online_cpu(cpu)
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kthread_unpark(per_cpu(softlockup_watchdog, cpu));
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}
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}
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static void watchdog_disable_all_cpus(void)
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{
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int cpu;
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unsigned int cpu;
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for_each_online_cpu(cpu)
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watchdog_disable(cpu);
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/* if all watchdogs are disabled, then they are disabled for the system */
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watchdog_enabled = 0;
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if (!watchdog_disabled) {
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watchdog_disabled = 1;
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for_each_online_cpu(cpu)
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kthread_park(per_cpu(softlockup_watchdog, cpu));
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}
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}
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/*
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* proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh
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*/
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@ -557,73 +509,36 @@ int proc_dowatchdog(struct ctl_table *table, int write,
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{
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int ret;
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if (watchdog_disabled < 0)
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return -ENODEV;
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ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
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if (ret || !write)
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goto out;
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return ret;
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if (watchdog_enabled && watchdog_thresh)
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watchdog_enable_all_cpus();
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else
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watchdog_disable_all_cpus();
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out:
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return ret;
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}
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#endif /* CONFIG_SYSCTL */
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/*
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* Create/destroy watchdog threads as CPUs come and go:
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*/
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static int __cpuinit
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cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
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{
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int hotcpu = (unsigned long)hcpu;
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switch (action) {
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case CPU_UP_PREPARE:
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case CPU_UP_PREPARE_FROZEN:
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watchdog_prepare_cpu(hotcpu);
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break;
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case CPU_ONLINE:
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case CPU_ONLINE_FROZEN:
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if (watchdog_enabled)
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watchdog_enable(hotcpu);
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break;
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#ifdef CONFIG_HOTPLUG_CPU
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case CPU_UP_CANCELED:
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case CPU_UP_CANCELED_FROZEN:
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watchdog_disable(hotcpu);
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break;
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case CPU_DEAD:
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case CPU_DEAD_FROZEN:
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watchdog_disable(hotcpu);
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break;
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#endif /* CONFIG_HOTPLUG_CPU */
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}
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/*
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* hardlockup and softlockup are not important enough
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* to block cpu bring up. Just always succeed and
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* rely on printk output to flag problems.
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*/
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return NOTIFY_OK;
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}
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static struct notifier_block __cpuinitdata cpu_nfb = {
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.notifier_call = cpu_callback
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static struct smp_hotplug_thread watchdog_threads = {
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.store = &softlockup_watchdog,
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.thread_should_run = watchdog_should_run,
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.thread_fn = watchdog,
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.thread_comm = "watchdog/%u",
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.setup = watchdog_enable,
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.park = watchdog_disable,
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.unpark = watchdog_enable,
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};
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void __init lockup_detector_init(void)
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{
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void *cpu = (void *)(long)smp_processor_id();
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int err;
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err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
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WARN_ON(notifier_to_errno(err));
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cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
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register_cpu_notifier(&cpu_nfb);
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return;
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if (smpboot_register_percpu_thread(&watchdog_threads)) {
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pr_err("Failed to create watchdog threads, disabled\n");
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watchdog_disabled = -ENODEV;
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}
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}
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