#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, touch_timestamp);
-static DEFINE_PER_CPU(unsigned long, print_timestamp);
-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 DEFINE_PER_CPU(bool, softlock_touch_sync);
static int __read_mostly did_panic;
int __read_mostly softlockup_thresh = 60;
{
int this_cpu = raw_smp_processor_id();
- __raw_get_cpu_var(touch_timestamp) = get_timestamp(this_cpu);
+ __raw_get_cpu_var(softlockup_touch_ts) = get_timestamp(this_cpu);
}
void touch_softlockup_watchdog(void)
{
- __raw_get_cpu_var(touch_timestamp) = 0;
+ __raw_get_cpu_var(softlockup_touch_ts) = 0;
}
EXPORT_SYMBOL(touch_softlockup_watchdog);
+void touch_softlockup_watchdog_sync(void)
+{
+ __raw_get_cpu_var(softlock_touch_sync) = true;
+ __raw_get_cpu_var(softlockup_touch_ts) = 0;
+}
+
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(touch_timestamp, cpu) = 0;
+ 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(void)
{
int this_cpu = smp_processor_id();
- unsigned long touch_timestamp = per_cpu(touch_timestamp, this_cpu);
- unsigned long print_timestamp;
+ 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;
/* Is detection switched off? */
- if (!per_cpu(watchdog_task, this_cpu) || softlockup_thresh <= 0) {
+ if (!per_cpu(softlockup_watchdog, this_cpu) || softlockup_thresh <= 0) {
/* Be sure we don't false trigger if switched back on */
- if (touch_timestamp)
- per_cpu(touch_timestamp, this_cpu) = 0;
+ if (touch_ts)
+ per_cpu(softlockup_touch_ts, this_cpu) = 0;
return;
}
- if (touch_timestamp == 0) {
+ if (touch_ts == 0) {
+ if (unlikely(per_cpu(softlock_touch_sync, this_cpu))) {
+ /*
+ * If the time stamp was touched atomically
+ * make sure the scheduler tick is up to date.
+ */
+ per_cpu(softlock_touch_sync, this_cpu) = false;
+ sched_clock_tick();
+ }
__touch_softlockup_watchdog();
return;
}
- print_timestamp = per_cpu(print_timestamp, this_cpu);
+ print_ts = per_cpu(softlockup_print_ts, this_cpu);
/* report at most once a second */
- if ((print_timestamp >= touch_timestamp &&
- print_timestamp < (touch_timestamp + 1)) ||
- did_panic) {
+ if (print_ts == touch_ts || did_panic)
return;
- }
/* do not print during early bootup: */
if (unlikely(system_state != SYSTEM_RUNNING)) {
now = get_timestamp(this_cpu);
- /* Wake up the high-prio watchdog task every second: */
- if (now > (touch_timestamp + 1))
- wake_up_process(per_cpu(watchdog_task, this_cpu));
+ /*
+ * Wake up the high-prio watchdog task twice per
+ * threshold timespan.
+ */
+ if (time_after(now - softlockup_thresh/2, touch_ts))
+ wake_up_process(per_cpu(softlockup_watchdog, this_cpu));
/* Warn about unreasonable delays: */
- if (now <= (touch_timestamp + softlockup_thresh))
+ if (time_before_eq(now - softlockup_thresh, touch_ts))
return;
- per_cpu(print_timestamp, this_cpu) = touch_timestamp;
+ 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_timestamp,
+ this_cpu, now - touch_ts,
current->comm, task_pid_nr(current));
print_modules();
+ print_irqtrace_events(current);
if (regs)
show_regs(regs);
else
}
/*
- * Have a reasonable limit on the number of tasks checked:
- */
-unsigned long __read_mostly sysctl_hung_task_check_count = 1024;
-
-/*
- * Zero means infinite timeout - no checking done:
- */
-unsigned long __read_mostly sysctl_hung_task_timeout_secs = 120;
-
-unsigned long __read_mostly sysctl_hung_task_warnings = 10;
-
-/*
- * Only do the hung-tasks check on one CPU:
- */
-static int check_cpu __read_mostly = -1;
-
-static void check_hung_task(struct task_struct *t, unsigned long now)
-{
- unsigned long switch_count = t->nvcsw + t->nivcsw;
-
- if (t->flags & PF_FROZEN)
- return;
-
- if (switch_count != t->last_switch_count || !t->last_switch_timestamp) {
- t->last_switch_count = switch_count;
- t->last_switch_timestamp = now;
- return;
- }
- if ((long)(now - t->last_switch_timestamp) <
- sysctl_hung_task_timeout_secs)
- return;
- if (sysctl_hung_task_warnings < 0)
- return;
- sysctl_hung_task_warnings--;
-
- /*
- * Ok, the task did not get scheduled for more than 2 minutes,
- * complain:
- */
- printk(KERN_ERR "INFO: task %s:%d blocked for more than "
- "%ld seconds.\n", t->comm, t->pid,
- sysctl_hung_task_timeout_secs);
- printk(KERN_ERR "\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
- " disables this message.\n");
- sched_show_task(t);
- __debug_show_held_locks(t);
-
- t->last_switch_timestamp = now;
- touch_nmi_watchdog();
-
- if (softlockup_panic)
- panic("softlockup: blocked tasks");
-}
-
-/*
- * Check whether a TASK_UNINTERRUPTIBLE does not get woken up for
- * a really long time (120 seconds). If that happens, print out
- * a warning.
- */
-static void check_hung_uninterruptible_tasks(int this_cpu)
-{
- int max_count = sysctl_hung_task_check_count;
- unsigned long now = get_timestamp(this_cpu);
- struct task_struct *g, *t;
-
- /*
- * If the system crashed already then all bets are off,
- * do not report extra hung tasks:
- */
- if ((tainted & TAINT_DIE) || did_panic)
- return;
-
- read_lock(&tasklist_lock);
- do_each_thread(g, t) {
- if (!--max_count)
- goto unlock;
- if (t->state & TASK_UNINTERRUPTIBLE)
- check_hung_task(t, now);
- } while_each_thread(g, t);
- unlock:
- read_unlock(&tasklist_lock);
-}
-
-/*
* The watchdog thread - runs every second and touches the timestamp.
*/
static int watchdog(void *__bind_cpu)
{
struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
- int this_cpu = (long)__bind_cpu;
sched_setscheduler(current, SCHED_FIFO, ¶m);
if (kthread_should_stop())
break;
- if (this_cpu == check_cpu) {
- if (sysctl_hung_task_timeout_secs)
- check_hung_uninterruptible_tasks(this_cpu);
- }
-
set_current_state(TASK_INTERRUPTIBLE);
}
__set_current_state(TASK_RUNNING);
switch (action) {
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
- BUG_ON(per_cpu(watchdog_task, hotcpu));
+ BUG_ON(per_cpu(softlockup_watchdog, hotcpu));
p = kthread_create(watchdog, hcpu, "watchdog/%d", hotcpu);
if (IS_ERR(p)) {
printk(KERN_ERR "watchdog for %i failed\n", hotcpu);
return NOTIFY_BAD;
}
- per_cpu(touch_timestamp, hotcpu) = 0;
- per_cpu(watchdog_task, hotcpu) = p;
+ per_cpu(softlockup_touch_ts, hotcpu) = 0;
+ per_cpu(softlockup_watchdog, hotcpu) = p;
kthread_bind(p, hotcpu);
break;
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
- check_cpu = any_online_cpu(cpu_online_map);
- wake_up_process(per_cpu(watchdog_task, hotcpu));
+ wake_up_process(per_cpu(softlockup_watchdog, hotcpu));
break;
#ifdef CONFIG_HOTPLUG_CPU
- case CPU_DOWN_PREPARE:
- case CPU_DOWN_PREPARE_FROZEN:
- if (hotcpu == check_cpu) {
- cpumask_t temp_cpu_online_map = cpu_online_map;
-
- cpu_clear(hotcpu, temp_cpu_online_map);
- check_cpu = any_online_cpu(temp_cpu_online_map);
- }
- break;
-
case CPU_UP_CANCELED:
case CPU_UP_CANCELED_FROZEN:
- if (!per_cpu(watchdog_task, hotcpu))
+ 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:
case CPU_DEAD_FROZEN:
- p = per_cpu(watchdog_task, hotcpu);
- per_cpu(watchdog_task, hotcpu) = NULL;
+ p = per_cpu(softlockup_watchdog, hotcpu);
+ per_cpu(softlockup_watchdog, hotcpu) = NULL;
kthread_stop(p);
break;
#endif /* CONFIG_HOTPLUG_CPU */
.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);
+ int err;
+
+ if (nosoftlockup)
+ return 0;
- BUG_ON(err == NOTIFY_BAD);
+ 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);
atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
+
+ return 0;
}
+early_initcall(spawn_softlockup_task);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff