/*
* Detect Soft Lockups
*
- * started by Ingo Molnar, (C) 2005, Red Hat
+ * started by Ingo Molnar, Copyright (C) 2005, 2006 Red Hat, Inc.
*
* this code detects soft lockups: incidents in where on a CPU
* the kernel does not reschedule for 10 seconds or more.
*/
-
#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>
static DEFINE_SPINLOCK(print_lock);
-static DEFINE_PER_CPU(unsigned long, timestamp) = 0;
-static DEFINE_PER_CPU(unsigned long, print_timestamp) = 0;
-static DEFINE_PER_CPU(struct task_struct *, watchdog_task);
+static DEFINE_PER_CPU(unsigned long, softlockup_touch_ts); /* touch timestamp */
+static DEFINE_PER_CPU(unsigned long, softlockup_print_ts); /* print timestamp */
+static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
+
+static int __read_mostly did_panic;
+int __read_mostly softlockup_thresh = 60;
+
+/*
+ * Should we panic (and reboot, if panic_timeout= is set) when a
+ * soft-lockup occurs:
+ */
+unsigned int __read_mostly softlockup_panic =
+ CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
-static int did_panic = 0;
-static int softlock_panic(struct notifier_block *this, unsigned long event,
- void *ptr)
+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
+softlock_panic(struct notifier_block *this, unsigned long event, void *ptr)
{
did_panic = 1;
.notifier_call = softlock_panic,
};
+/*
+ * 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 void __touch_softlockup_watchdog(void)
+{
+ int this_cpu = raw_smp_processor_id();
+
+ __raw_get_cpu_var(softlockup_touch_ts) = get_timestamp(this_cpu);
+}
+
void touch_softlockup_watchdog(void)
{
- per_cpu(timestamp, raw_smp_processor_id()) = jiffies;
+ __raw_get_cpu_var(softlockup_touch_ts) = 0;
}
EXPORT_SYMBOL(touch_softlockup_watchdog);
+void touch_all_softlockup_watchdogs(void)
+{
+ int cpu;
+
+ /* Cause each CPU to re-update its timestamp rather than complain */
+ for_each_online_cpu(cpu)
+ per_cpu(softlockup_touch_ts, cpu) = 0;
+}
+EXPORT_SYMBOL(touch_all_softlockup_watchdogs);
+
+int proc_dosoftlockup_thresh(struct ctl_table *table, int write,
+ void __user *buffer,
+ size_t *lenp, loff_t *ppos)
+{
+ touch_all_softlockup_watchdogs();
+ return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+}
+
/*
* This callback runs from the timer interrupt, and checks
* whether the watchdog thread has hung or not:
*/
-void softlockup_tick(struct pt_regs *regs)
+void softlockup_tick(void)
{
int this_cpu = smp_processor_id();
- unsigned long timestamp = per_cpu(timestamp, this_cpu);
+ unsigned long touch_ts = per_cpu(softlockup_touch_ts, this_cpu);
+ unsigned long print_ts;
+ struct pt_regs *regs = get_irq_regs();
+ unsigned long now;
- if (per_cpu(print_timestamp, this_cpu) == timestamp)
+ /* Is detection switched off? */
+ if (!per_cpu(softlockup_watchdog, this_cpu) || softlockup_thresh <= 0) {
+ /* Be sure we don't false trigger if switched back on */
+ if (touch_ts)
+ per_cpu(softlockup_touch_ts, this_cpu) = 0;
return;
+ }
- /* Do not cause a second panic when there already was one */
- if (did_panic)
+ if (touch_ts == 0) {
+ __touch_softlockup_watchdog();
return;
+ }
- if (time_after(jiffies, timestamp + 10*HZ)) {
- per_cpu(print_timestamp, this_cpu) = timestamp;
+ print_ts = per_cpu(softlockup_print_ts, this_cpu);
- spin_lock(&print_lock);
- printk(KERN_ERR "BUG: soft lockup detected on CPU#%d!\n",
- this_cpu);
- show_regs(regs);
- spin_unlock(&print_lock);
+ /* report at most once a second */
+ if (print_ts == touch_ts || did_panic)
+ return;
+
+ /* do not print during early bootup: */
+ if (unlikely(system_state != SYSTEM_RUNNING)) {
+ __touch_softlockup_watchdog();
+ return;
}
+
+ now = get_timestamp(this_cpu);
+
+ /*
+ * Wake up the high-prio watchdog task twice per
+ * threshold timespan.
+ */
+ if (now > touch_ts + softlockup_thresh/2)
+ wake_up_process(per_cpu(softlockup_watchdog, this_cpu));
+
+ /* Warn about unreasonable delays: */
+ if (now <= (touch_ts + softlockup_thresh))
+ return;
+
+ per_cpu(softlockup_print_ts, this_cpu) = touch_ts;
+
+ spin_lock(&print_lock);
+ printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %lus! [%s:%d]\n",
+ this_cpu, now - touch_ts,
+ current->comm, task_pid_nr(current));
+ print_modules();
+ print_irqtrace_events(current);
+ if (regs)
+ show_regs(regs);
+ else
+ dump_stack();
+ spin_unlock(&print_lock);
+
+ if (softlockup_panic)
+ panic("softlockup: hung tasks");
}
/*
* The watchdog thread - runs every second and touches the timestamp.
*/
-static int watchdog(void * __bind_cpu)
+static int watchdog(void *__bind_cpu)
{
- struct sched_param param = { .sched_priority = 99 };
+ struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
sched_setscheduler(current, SCHED_FIFO, ¶m);
- current->flags |= PF_NOFREEZE;
- set_current_state(TASK_INTERRUPTIBLE);
+ /* initialize timestamp */
+ __touch_softlockup_watchdog();
+ set_current_state(TASK_INTERRUPTIBLE);
/*
- * Run briefly once per second - if this gets delayed for
- * more than 10 seconds then the debug-printout triggers
- * in softlockup_tick():
+ * 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 softlockup_tick().
*/
while (!kthread_should_stop()) {
- msleep_interruptible(1000);
- touch_softlockup_watchdog();
+ __touch_softlockup_watchdog();
+ schedule();
+
+ if (kthread_should_stop())
+ break;
+
+ set_current_state(TASK_INTERRUPTIBLE);
}
__set_current_state(TASK_RUNNING);
/*
* Create/destroy watchdog threads as CPUs come and go:
*/
-static int __devinit
+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:
- BUG_ON(per_cpu(watchdog_task, hotcpu));
+ case CPU_UP_PREPARE_FROZEN:
+ BUG_ON(per_cpu(softlockup_watchdog, hotcpu));
p = kthread_create(watchdog, hcpu, "watchdog/%d", hotcpu);
if (IS_ERR(p)) {
- printk("watchdog for %i failed\n", hotcpu);
+ printk(KERN_ERR "watchdog for %i failed\n", hotcpu);
return NOTIFY_BAD;
}
- per_cpu(watchdog_task, hotcpu) = p;
+ per_cpu(softlockup_touch_ts, hotcpu) = 0;
+ per_cpu(softlockup_watchdog, hotcpu) = p;
kthread_bind(p, hotcpu);
- break;
+ break;
case CPU_ONLINE:
-
- wake_up_process(per_cpu(watchdog_task, hotcpu));
+ case CPU_ONLINE_FROZEN:
+ wake_up_process(per_cpu(softlockup_watchdog, hotcpu));
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED:
+ case CPU_UP_CANCELED_FROZEN:
+ if (!per_cpu(softlockup_watchdog, hotcpu))
+ break;
/* Unbind so it can run. Fall thru. */
- kthread_bind(per_cpu(watchdog_task, hotcpu),
- any_online_cpu(cpu_online_map));
+ kthread_bind(per_cpu(softlockup_watchdog, hotcpu),
+ cpumask_any(cpu_online_mask));
case CPU_DEAD:
- p = per_cpu(watchdog_task, hotcpu);
- per_cpu(watchdog_task, hotcpu) = NULL;
+ case CPU_DEAD_FROZEN:
+ p = per_cpu(softlockup_watchdog, hotcpu);
+ per_cpu(softlockup_watchdog, hotcpu) = NULL;
kthread_stop(p);
break;
#endif /* CONFIG_HOTPLUG_CPU */
- }
+ }
return NOTIFY_OK;
}
-static struct notifier_block __devinitdata cpu_nfb = {
+static struct notifier_block __cpuinitdata cpu_nfb = {
.notifier_call = cpu_callback
};
-__init void spawn_softlockup_task(void)
+static int __initdata nosoftlockup;
+
+static int __init nosoftlockup_setup(char *str)
+{
+ nosoftlockup = 1;
+ return 1;
+}
+__setup("nosoftlockup", nosoftlockup_setup);
+
+static int __init spawn_softlockup_task(void)
{
void *cpu = (void *)(long)smp_processor_id();
+ int err;
- cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
+ if (nosoftlockup)
+ return 0;
+
+ err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
+ if (err == NOTIFY_BAD) {
+ BUG();
+ return 1;
+ }
cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
register_cpu_notifier(&cpu_nfb);
- notifier_chain_register(&panic_notifier_list, &panic_block);
-}
+ atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
+ return 0;
+}
+early_initcall(spawn_softlockup_task);
Code Review / linux-2.6.git / blobdiff