1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
|
/*
* Detect Soft Lockups
*
* 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/init.h>
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/notifier.h>
#include <linux/module.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 int did_panic = 0;
static int
softlock_panic(struct notifier_block *this, unsigned long event, void *ptr)
{
did_panic = 1;
return NOTIFY_DONE;
}
static struct notifier_block panic_block = {
.notifier_call = softlock_panic,
};
void touch_softlockup_watchdog(void)
{
per_cpu(touch_timestamp, raw_smp_processor_id()) = jiffies;
}
EXPORT_SYMBOL(touch_softlockup_watchdog);
/*
* 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);
/* prevent double reports: */
if (per_cpu(print_timestamp, this_cpu) == touch_timestamp ||
did_panic ||
!per_cpu(watchdog_task, this_cpu))
return;
/* do not print during early bootup: */
if (unlikely(system_state != SYSTEM_RUNNING)) {
touch_softlockup_watchdog();
return;
}
/* Wake up the high-prio watchdog task every second: */
if (time_after(jiffies, touch_timestamp + HZ))
wake_up_process(per_cpu(watchdog_task, this_cpu));
/* Warn about unreasonable 10+ seconds delays: */
if (time_after(jiffies, touch_timestamp + 10*HZ)) {
per_cpu(print_timestamp, this_cpu) = touch_timestamp;
spin_lock(&print_lock);
printk(KERN_ERR "BUG: soft lockup detected on CPU#%d!\n",
this_cpu);
dump_stack();
spin_unlock(&print_lock);
}
}
/*
* The watchdog thread - runs every second and touches the timestamp.
*/
static int watchdog(void * __bind_cpu)
{
struct sched_param param = { .sched_priority = 99 };
sched_setscheduler(current, SCHED_FIFO, ¶m);
current->flags |= PF_NOFREEZE;
/*
* Run briefly once per second to reset the softlockup timestamp.
* If this gets delayed for more than 10 seconds then the
* debug-printout triggers in softlockup_tick().
*/
while (!kthread_should_stop()) {
set_current_state(TASK_INTERRUPTIBLE);
touch_softlockup_watchdog();
schedule();
}
return 0;
}
/*
* Create/destroy watchdog threads as CPUs come and go:
*/
static int __devinit
cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
{
int hotcpu = (unsigned long)hcpu;
struct task_struct *p;
switch (action) {
case CPU_UP_PREPARE:
BUG_ON(per_cpu(watchdog_task, hotcpu));
p = kthread_create(watchdog, hcpu, "watchdog/%d", hotcpu);
if (IS_ERR(p)) {
printk("watchdog for %i failed\n", hotcpu);
return NOTIFY_BAD;
}
per_cpu(touch_timestamp, hotcpu) = jiffies;
per_cpu(watchdog_task, hotcpu) = p;
kthread_bind(p, hotcpu);
break;
case CPU_ONLINE:
wake_up_process(per_cpu(watchdog_task, hotcpu));
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED:
/* Unbind so it can run. Fall thru. */
kthread_bind(per_cpu(watchdog_task, hotcpu),
any_online_cpu(cpu_online_map));
case CPU_DEAD:
p = per_cpu(watchdog_task, hotcpu);
per_cpu(watchdog_task, hotcpu) = NULL;
kthread_stop(p);
break;
#endif /* CONFIG_HOTPLUG_CPU */
}
return NOTIFY_OK;
}
static struct notifier_block cpu_nfb = {
.notifier_call = cpu_callback
};
__init void spawn_softlockup_task(void)
{
void *cpu = (void *)(long)smp_processor_id();
cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
register_cpu_notifier(&cpu_nfb);
atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
}
|
