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Commit | Line | Data |
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58687acb DZ |
1 | /* |
2 | * Detect hard and soft lockups on a system | |
3 | * | |
4 | * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc. | |
5 | * | |
6 | * this code detects hard lockups: incidents in where on a CPU | |
7 | * the kernel does not respond to anything except NMI. | |
8 | * | |
9 | * Note: Most of this code is borrowed heavily from softlockup.c, | |
10 | * so thanks to Ingo for the initial implementation. | |
11 | * Some chunks also taken from arch/x86/kernel/apic/nmi.c, thanks | |
12 | * to those contributors as well. | |
13 | */ | |
14 | ||
15 | #include <linux/mm.h> | |
16 | #include <linux/cpu.h> | |
17 | #include <linux/nmi.h> | |
18 | #include <linux/init.h> | |
19 | #include <linux/delay.h> | |
20 | #include <linux/freezer.h> | |
21 | #include <linux/kthread.h> | |
22 | #include <linux/lockdep.h> | |
23 | #include <linux/notifier.h> | |
24 | #include <linux/module.h> | |
25 | #include <linux/sysctl.h> | |
26 | ||
27 | #include <asm/irq_regs.h> | |
28 | #include <linux/perf_event.h> | |
29 | ||
30 | int watchdog_enabled; | |
31 | int __read_mostly softlockup_thresh = 60; | |
32 | ||
33 | static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); | |
34 | static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog); | |
35 | static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer); | |
36 | static DEFINE_PER_CPU(bool, softlockup_touch_sync); | |
58687acb | 37 | static DEFINE_PER_CPU(bool, soft_watchdog_warn); |
23637d47 | 38 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
cafcd80d DZ |
39 | static DEFINE_PER_CPU(bool, hard_watchdog_warn); |
40 | static DEFINE_PER_CPU(bool, watchdog_nmi_touch); | |
58687acb DZ |
41 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); |
42 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); | |
43 | static DEFINE_PER_CPU(struct perf_event *, watchdog_ev); | |
44 | #endif | |
45 | ||
433039e9 | 46 | static int no_watchdog; |
58687acb DZ |
47 | |
48 | ||
49 | /* boot commands */ | |
50 | /* | |
51 | * Should we panic when a soft-lockup or hard-lockup occurs: | |
52 | */ | |
23637d47 | 53 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb DZ |
54 | static int hardlockup_panic; |
55 | ||
56 | static int __init hardlockup_panic_setup(char *str) | |
57 | { | |
58 | if (!strncmp(str, "panic", 5)) | |
59 | hardlockup_panic = 1; | |
60 | return 1; | |
61 | } | |
62 | __setup("nmi_watchdog=", hardlockup_panic_setup); | |
63 | #endif | |
64 | ||
65 | unsigned int __read_mostly softlockup_panic = | |
66 | CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE; | |
67 | ||
68 | static int __init softlockup_panic_setup(char *str) | |
69 | { | |
70 | softlockup_panic = simple_strtoul(str, NULL, 0); | |
71 | ||
72 | return 1; | |
73 | } | |
74 | __setup("softlockup_panic=", softlockup_panic_setup); | |
75 | ||
76 | static int __init nowatchdog_setup(char *str) | |
77 | { | |
78 | no_watchdog = 1; | |
79 | return 1; | |
80 | } | |
81 | __setup("nowatchdog", nowatchdog_setup); | |
82 | ||
83 | /* deprecated */ | |
84 | static int __init nosoftlockup_setup(char *str) | |
85 | { | |
86 | no_watchdog = 1; | |
87 | return 1; | |
88 | } | |
89 | __setup("nosoftlockup", nosoftlockup_setup); | |
90 | /* */ | |
91 | ||
92 | ||
93 | /* | |
94 | * Returns seconds, approximately. We don't need nanosecond | |
95 | * resolution, and we don't need to waste time with a big divide when | |
96 | * 2^30ns == 1.074s. | |
97 | */ | |
98 | static unsigned long get_timestamp(int this_cpu) | |
99 | { | |
100 | return cpu_clock(this_cpu) >> 30LL; /* 2^30 ~= 10^9 */ | |
101 | } | |
102 | ||
103 | static unsigned long get_sample_period(void) | |
104 | { | |
105 | /* | |
106 | * convert softlockup_thresh from seconds to ns | |
107 | * the divide by 5 is to give hrtimer 5 chances to | |
108 | * increment before the hardlockup detector generates | |
109 | * a warning | |
110 | */ | |
111 | return softlockup_thresh / 5 * NSEC_PER_SEC; | |
112 | } | |
113 | ||
114 | /* Commands for resetting the watchdog */ | |
115 | static void __touch_watchdog(void) | |
116 | { | |
26e09c6e | 117 | int this_cpu = smp_processor_id(); |
58687acb DZ |
118 | |
119 | __get_cpu_var(watchdog_touch_ts) = get_timestamp(this_cpu); | |
120 | } | |
121 | ||
332fbdbc | 122 | void touch_softlockup_watchdog(void) |
58687acb | 123 | { |
68d3f1d8 | 124 | __raw_get_cpu_var(watchdog_touch_ts) = 0; |
58687acb | 125 | } |
0167c781 | 126 | EXPORT_SYMBOL(touch_softlockup_watchdog); |
58687acb | 127 | |
332fbdbc | 128 | void touch_all_softlockup_watchdogs(void) |
58687acb DZ |
129 | { |
130 | int cpu; | |
131 | ||
132 | /* | |
133 | * this is done lockless | |
134 | * do we care if a 0 races with a timestamp? | |
135 | * all it means is the softlock check starts one cycle later | |
136 | */ | |
137 | for_each_online_cpu(cpu) | |
138 | per_cpu(watchdog_touch_ts, cpu) = 0; | |
139 | } | |
140 | ||
cafcd80d | 141 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb DZ |
142 | void touch_nmi_watchdog(void) |
143 | { | |
68d3f1d8 DZ |
144 | if (watchdog_enabled) { |
145 | unsigned cpu; | |
146 | ||
147 | for_each_present_cpu(cpu) { | |
148 | if (per_cpu(watchdog_nmi_touch, cpu) != true) | |
149 | per_cpu(watchdog_nmi_touch, cpu) = true; | |
150 | } | |
151 | } | |
332fbdbc | 152 | touch_softlockup_watchdog(); |
58687acb DZ |
153 | } |
154 | EXPORT_SYMBOL(touch_nmi_watchdog); | |
155 | ||
cafcd80d DZ |
156 | #endif |
157 | ||
58687acb DZ |
158 | void touch_softlockup_watchdog_sync(void) |
159 | { | |
160 | __raw_get_cpu_var(softlockup_touch_sync) = true; | |
161 | __raw_get_cpu_var(watchdog_touch_ts) = 0; | |
162 | } | |
163 | ||
23637d47 | 164 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb | 165 | /* watchdog detector functions */ |
26e09c6e | 166 | static int is_hardlockup(void) |
58687acb | 167 | { |
26e09c6e | 168 | unsigned long hrint = __get_cpu_var(hrtimer_interrupts); |
58687acb | 169 | |
26e09c6e | 170 | if (__get_cpu_var(hrtimer_interrupts_saved) == hrint) |
58687acb DZ |
171 | return 1; |
172 | ||
26e09c6e | 173 | __get_cpu_var(hrtimer_interrupts_saved) = hrint; |
58687acb DZ |
174 | return 0; |
175 | } | |
176 | #endif | |
177 | ||
26e09c6e | 178 | static int is_softlockup(unsigned long touch_ts) |
58687acb | 179 | { |
26e09c6e | 180 | unsigned long now = get_timestamp(smp_processor_id()); |
58687acb DZ |
181 | |
182 | /* Warn about unreasonable delays: */ | |
183 | if (time_after(now, touch_ts + softlockup_thresh)) | |
184 | return now - touch_ts; | |
185 | ||
186 | return 0; | |
187 | } | |
188 | ||
23637d47 | 189 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb DZ |
190 | static struct perf_event_attr wd_hw_attr = { |
191 | .type = PERF_TYPE_HARDWARE, | |
192 | .config = PERF_COUNT_HW_CPU_CYCLES, | |
193 | .size = sizeof(struct perf_event_attr), | |
194 | .pinned = 1, | |
195 | .disabled = 1, | |
196 | }; | |
197 | ||
198 | /* Callback function for perf event subsystem */ | |
277b1998 | 199 | static void watchdog_overflow_callback(struct perf_event *event, int nmi, |
58687acb DZ |
200 | struct perf_sample_data *data, |
201 | struct pt_regs *regs) | |
202 | { | |
c6db67cd PZ |
203 | /* Ensure the watchdog never gets throttled */ |
204 | event->hw.interrupts = 0; | |
205 | ||
d7c54733 DZ |
206 | if (__get_cpu_var(watchdog_nmi_touch) == true) { |
207 | __get_cpu_var(watchdog_nmi_touch) = false; | |
58687acb DZ |
208 | return; |
209 | } | |
210 | ||
211 | /* check for a hardlockup | |
212 | * This is done by making sure our timer interrupt | |
213 | * is incrementing. The timer interrupt should have | |
214 | * fired multiple times before we overflow'd. If it hasn't | |
215 | * then this is a good indication the cpu is stuck | |
216 | */ | |
26e09c6e DZ |
217 | if (is_hardlockup()) { |
218 | int this_cpu = smp_processor_id(); | |
219 | ||
58687acb DZ |
220 | /* only print hardlockups once */ |
221 | if (__get_cpu_var(hard_watchdog_warn) == true) | |
222 | return; | |
223 | ||
224 | if (hardlockup_panic) | |
225 | panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu); | |
226 | else | |
227 | WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu); | |
228 | ||
229 | __get_cpu_var(hard_watchdog_warn) = true; | |
230 | return; | |
231 | } | |
232 | ||
233 | __get_cpu_var(hard_watchdog_warn) = false; | |
234 | return; | |
235 | } | |
236 | static void watchdog_interrupt_count(void) | |
237 | { | |
238 | __get_cpu_var(hrtimer_interrupts)++; | |
239 | } | |
240 | #else | |
241 | static inline void watchdog_interrupt_count(void) { return; } | |
23637d47 | 242 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
58687acb DZ |
243 | |
244 | /* watchdog kicker functions */ | |
245 | static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) | |
246 | { | |
58687acb DZ |
247 | unsigned long touch_ts = __get_cpu_var(watchdog_touch_ts); |
248 | struct pt_regs *regs = get_irq_regs(); | |
249 | int duration; | |
250 | ||
251 | /* kick the hardlockup detector */ | |
252 | watchdog_interrupt_count(); | |
253 | ||
254 | /* kick the softlockup detector */ | |
255 | wake_up_process(__get_cpu_var(softlockup_watchdog)); | |
256 | ||
257 | /* .. and repeat */ | |
258 | hrtimer_forward_now(hrtimer, ns_to_ktime(get_sample_period())); | |
259 | ||
260 | if (touch_ts == 0) { | |
26e09c6e | 261 | if (unlikely(__get_cpu_var(softlockup_touch_sync))) { |
58687acb DZ |
262 | /* |
263 | * If the time stamp was touched atomically | |
264 | * make sure the scheduler tick is up to date. | |
265 | */ | |
26e09c6e | 266 | __get_cpu_var(softlockup_touch_sync) = false; |
58687acb DZ |
267 | sched_clock_tick(); |
268 | } | |
269 | __touch_watchdog(); | |
270 | return HRTIMER_RESTART; | |
271 | } | |
272 | ||
273 | /* check for a softlockup | |
274 | * This is done by making sure a high priority task is | |
275 | * being scheduled. The task touches the watchdog to | |
276 | * indicate it is getting cpu time. If it hasn't then | |
277 | * this is a good indication some task is hogging the cpu | |
278 | */ | |
26e09c6e | 279 | duration = is_softlockup(touch_ts); |
58687acb DZ |
280 | if (unlikely(duration)) { |
281 | /* only warn once */ | |
282 | if (__get_cpu_var(soft_watchdog_warn) == true) | |
283 | return HRTIMER_RESTART; | |
284 | ||
285 | printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", | |
26e09c6e | 286 | smp_processor_id(), duration, |
58687acb DZ |
287 | current->comm, task_pid_nr(current)); |
288 | print_modules(); | |
289 | print_irqtrace_events(current); | |
290 | if (regs) | |
291 | show_regs(regs); | |
292 | else | |
293 | dump_stack(); | |
294 | ||
295 | if (softlockup_panic) | |
296 | panic("softlockup: hung tasks"); | |
297 | __get_cpu_var(soft_watchdog_warn) = true; | |
298 | } else | |
299 | __get_cpu_var(soft_watchdog_warn) = false; | |
300 | ||
301 | return HRTIMER_RESTART; | |
302 | } | |
303 | ||
304 | ||
305 | /* | |
306 | * The watchdog thread - touches the timestamp. | |
307 | */ | |
26e09c6e | 308 | static int watchdog(void *unused) |
58687acb DZ |
309 | { |
310 | struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; | |
26e09c6e | 311 | struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); |
58687acb DZ |
312 | |
313 | sched_setscheduler(current, SCHED_FIFO, ¶m); | |
314 | ||
315 | /* initialize timestamp */ | |
316 | __touch_watchdog(); | |
317 | ||
318 | /* kick off the timer for the hardlockup detector */ | |
319 | /* done here because hrtimer_start can only pin to smp_processor_id() */ | |
320 | hrtimer_start(hrtimer, ns_to_ktime(get_sample_period()), | |
321 | HRTIMER_MODE_REL_PINNED); | |
322 | ||
323 | set_current_state(TASK_INTERRUPTIBLE); | |
324 | /* | |
325 | * Run briefly once per second to reset the softlockup timestamp. | |
326 | * If this gets delayed for more than 60 seconds then the | |
26e09c6e | 327 | * debug-printout triggers in watchdog_timer_fn(). |
58687acb DZ |
328 | */ |
329 | while (!kthread_should_stop()) { | |
330 | __touch_watchdog(); | |
331 | schedule(); | |
332 | ||
333 | if (kthread_should_stop()) | |
334 | break; | |
335 | ||
336 | set_current_state(TASK_INTERRUPTIBLE); | |
337 | } | |
338 | __set_current_state(TASK_RUNNING); | |
339 | ||
340 | return 0; | |
341 | } | |
342 | ||
343 | ||
23637d47 | 344 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb DZ |
345 | static int watchdog_nmi_enable(int cpu) |
346 | { | |
347 | struct perf_event_attr *wd_attr; | |
348 | struct perf_event *event = per_cpu(watchdog_ev, cpu); | |
349 | ||
350 | /* is it already setup and enabled? */ | |
351 | if (event && event->state > PERF_EVENT_STATE_OFF) | |
352 | goto out; | |
353 | ||
354 | /* it is setup but not enabled */ | |
355 | if (event != NULL) | |
356 | goto out_enable; | |
357 | ||
358 | /* Try to register using hardware perf events */ | |
359 | wd_attr = &wd_hw_attr; | |
360 | wd_attr->sample_period = hw_nmi_get_sample_period(); | |
38a81da2 | 361 | event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback); |
58687acb DZ |
362 | if (!IS_ERR(event)) { |
363 | printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n"); | |
364 | goto out_save; | |
365 | } | |
366 | ||
367 | printk(KERN_ERR "NMI watchdog failed to create perf event on cpu%i: %p\n", cpu, event); | |
eac24335 | 368 | return PTR_ERR(event); |
58687acb DZ |
369 | |
370 | /* success path */ | |
371 | out_save: | |
372 | per_cpu(watchdog_ev, cpu) = event; | |
373 | out_enable: | |
374 | perf_event_enable(per_cpu(watchdog_ev, cpu)); | |
375 | out: | |
376 | return 0; | |
377 | } | |
378 | ||
379 | static void watchdog_nmi_disable(int cpu) | |
380 | { | |
381 | struct perf_event *event = per_cpu(watchdog_ev, cpu); | |
382 | ||
383 | if (event) { | |
384 | perf_event_disable(event); | |
385 | per_cpu(watchdog_ev, cpu) = NULL; | |
386 | ||
387 | /* should be in cleanup, but blocks oprofile */ | |
388 | perf_event_release_kernel(event); | |
389 | } | |
390 | return; | |
391 | } | |
392 | #else | |
393 | static int watchdog_nmi_enable(int cpu) { return 0; } | |
394 | static void watchdog_nmi_disable(int cpu) { return; } | |
23637d47 | 395 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
58687acb DZ |
396 | |
397 | /* prepare/enable/disable routines */ | |
398 | static int watchdog_prepare_cpu(int cpu) | |
399 | { | |
400 | struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu); | |
401 | ||
402 | WARN_ON(per_cpu(softlockup_watchdog, cpu)); | |
403 | hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
404 | hrtimer->function = watchdog_timer_fn; | |
405 | ||
406 | return 0; | |
407 | } | |
408 | ||
409 | static int watchdog_enable(int cpu) | |
410 | { | |
411 | struct task_struct *p = per_cpu(softlockup_watchdog, cpu); | |
eac24335 | 412 | int err; |
58687acb DZ |
413 | |
414 | /* enable the perf event */ | |
eac24335 AM |
415 | err = watchdog_nmi_enable(cpu); |
416 | if (err) | |
417 | return err; | |
58687acb DZ |
418 | |
419 | /* create the watchdog thread */ | |
420 | if (!p) { | |
421 | p = kthread_create(watchdog, (void *)(unsigned long)cpu, "watchdog/%d", cpu); | |
422 | if (IS_ERR(p)) { | |
423 | printk(KERN_ERR "softlockup watchdog for %i failed\n", cpu); | |
eac24335 | 424 | return PTR_ERR(p); |
58687acb DZ |
425 | } |
426 | kthread_bind(p, cpu); | |
427 | per_cpu(watchdog_touch_ts, cpu) = 0; | |
428 | per_cpu(softlockup_watchdog, cpu) = p; | |
429 | wake_up_process(p); | |
430 | } | |
431 | ||
68d3f1d8 DZ |
432 | /* if any cpu succeeds, watchdog is considered enabled for the system */ |
433 | watchdog_enabled = 1; | |
434 | ||
58687acb DZ |
435 | return 0; |
436 | } | |
437 | ||
438 | static void watchdog_disable(int cpu) | |
439 | { | |
440 | struct task_struct *p = per_cpu(softlockup_watchdog, cpu); | |
441 | struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu); | |
442 | ||
443 | /* | |
444 | * cancel the timer first to stop incrementing the stats | |
445 | * and waking up the kthread | |
446 | */ | |
447 | hrtimer_cancel(hrtimer); | |
448 | ||
449 | /* disable the perf event */ | |
450 | watchdog_nmi_disable(cpu); | |
451 | ||
452 | /* stop the watchdog thread */ | |
453 | if (p) { | |
454 | per_cpu(softlockup_watchdog, cpu) = NULL; | |
455 | kthread_stop(p); | |
456 | } | |
58687acb DZ |
457 | } |
458 | ||
459 | static void watchdog_enable_all_cpus(void) | |
460 | { | |
461 | int cpu; | |
eb703f98 | 462 | int result = 0; |
58687acb DZ |
463 | |
464 | for_each_online_cpu(cpu) | |
465 | result += watchdog_enable(cpu); | |
466 | ||
467 | if (result) | |
468 | printk(KERN_ERR "watchdog: failed to be enabled on some cpus\n"); | |
469 | ||
470 | } | |
471 | ||
472 | static void watchdog_disable_all_cpus(void) | |
473 | { | |
474 | int cpu; | |
475 | ||
d9ca07a0 SE |
476 | if (no_watchdog) |
477 | return; | |
478 | ||
58687acb DZ |
479 | for_each_online_cpu(cpu) |
480 | watchdog_disable(cpu); | |
481 | ||
482 | /* if all watchdogs are disabled, then they are disabled for the system */ | |
483 | watchdog_enabled = 0; | |
484 | } | |
485 | ||
486 | ||
487 | /* sysctl functions */ | |
488 | #ifdef CONFIG_SYSCTL | |
489 | /* | |
490 | * proc handler for /proc/sys/kernel/nmi_watchdog | |
491 | */ | |
492 | ||
493 | int proc_dowatchdog_enabled(struct ctl_table *table, int write, | |
494 | void __user *buffer, size_t *length, loff_t *ppos) | |
495 | { | |
496 | proc_dointvec(table, write, buffer, length, ppos); | |
497 | ||
498 | if (watchdog_enabled) | |
499 | watchdog_enable_all_cpus(); | |
500 | else | |
501 | watchdog_disable_all_cpus(); | |
502 | return 0; | |
503 | } | |
504 | ||
505 | int proc_dowatchdog_thresh(struct ctl_table *table, int write, | |
506 | void __user *buffer, | |
507 | size_t *lenp, loff_t *ppos) | |
508 | { | |
509 | return proc_dointvec_minmax(table, write, buffer, lenp, ppos); | |
510 | } | |
58687acb DZ |
511 | #endif /* CONFIG_SYSCTL */ |
512 | ||
513 | ||
514 | /* | |
515 | * Create/destroy watchdog threads as CPUs come and go: | |
516 | */ | |
517 | static int __cpuinit | |
518 | cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) | |
519 | { | |
520 | int hotcpu = (unsigned long)hcpu; | |
eac24335 | 521 | int err = 0; |
58687acb DZ |
522 | |
523 | switch (action) { | |
524 | case CPU_UP_PREPARE: | |
525 | case CPU_UP_PREPARE_FROZEN: | |
eac24335 | 526 | err = watchdog_prepare_cpu(hotcpu); |
58687acb DZ |
527 | break; |
528 | case CPU_ONLINE: | |
529 | case CPU_ONLINE_FROZEN: | |
eac24335 | 530 | err = watchdog_enable(hotcpu); |
58687acb DZ |
531 | break; |
532 | #ifdef CONFIG_HOTPLUG_CPU | |
533 | case CPU_UP_CANCELED: | |
534 | case CPU_UP_CANCELED_FROZEN: | |
535 | watchdog_disable(hotcpu); | |
536 | break; | |
537 | case CPU_DEAD: | |
538 | case CPU_DEAD_FROZEN: | |
539 | watchdog_disable(hotcpu); | |
540 | break; | |
541 | #endif /* CONFIG_HOTPLUG_CPU */ | |
542 | } | |
eac24335 | 543 | return notifier_from_errno(err); |
58687acb DZ |
544 | } |
545 | ||
546 | static struct notifier_block __cpuinitdata cpu_nfb = { | |
547 | .notifier_call = cpu_callback | |
548 | }; | |
549 | ||
550 | static int __init spawn_watchdog_task(void) | |
551 | { | |
552 | void *cpu = (void *)(long)smp_processor_id(); | |
553 | int err; | |
554 | ||
555 | if (no_watchdog) | |
556 | return 0; | |
557 | ||
558 | err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu); | |
eac24335 | 559 | WARN_ON(notifier_to_errno(err)); |
58687acb DZ |
560 | |
561 | cpu_callback(&cpu_nfb, CPU_ONLINE, cpu); | |
562 | register_cpu_notifier(&cpu_nfb); | |
563 | ||
58687acb DZ |
564 | return 0; |
565 | } | |
566 | early_initcall(spawn_watchdog_task); |