1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Detect hard and soft lockups on a system
4 *
5 * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
6 *
7 * Note: Most of this code is borrowed heavily from the original softlockup
8 * detector, so thanks to Ingo for the initial implementation.
9 * Some chunks also taken from the old x86-specific nmi watchdog code, thanks
10 * to those contributors as well.
11 */
12
13 #define pr_fmt(fmt) "watchdog: " fmt
14
15 #include <linux/mm.h>
16 #include <linux/cpu.h>
17 #include <linux/nmi.h>
18 #include <linux/init.h>
19 #include <linux/module.h>
20 #include <linux/sysctl.h>
21 #include <linux/tick.h>
22 #include <linux/sched/clock.h>
23 #include <linux/sched/debug.h>
24 #include <linux/sched/isolation.h>
25 #include <linux/stop_machine.h>
26
27 #include <asm/irq_regs.h>
28 #include <linux/kvm_para.h>
29
30 static DEFINE_MUTEX(watchdog_mutex);
31
32 #if defined(CONFIG_HARDLOCKUP_DETECTOR) || defined(CONFIG_HAVE_NMI_WATCHDOG)
33 # define WATCHDOG_DEFAULT (SOFT_WATCHDOG_ENABLED | NMI_WATCHDOG_ENABLED)
34 # define NMI_WATCHDOG_DEFAULT 1
35 #else
36 # define WATCHDOG_DEFAULT (SOFT_WATCHDOG_ENABLED)
37 # define NMI_WATCHDOG_DEFAULT 0
38 #endif
39
40 unsigned long __read_mostly watchdog_enabled;
41 int __read_mostly watchdog_user_enabled = 1;
42 int __read_mostly nmi_watchdog_user_enabled = NMI_WATCHDOG_DEFAULT;
43 int __read_mostly soft_watchdog_user_enabled = 1;
44 int __read_mostly watchdog_thresh = 10;
45 static int __read_mostly nmi_watchdog_available;
46
47 struct cpumask watchdog_cpumask __read_mostly;
48 unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask);
49
50 #ifdef CONFIG_HARDLOCKUP_DETECTOR
51
52 # ifdef CONFIG_SMP
53 int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
54 # endif /* CONFIG_SMP */
55
56 /*
57 * Should we panic when a soft-lockup or hard-lockup occurs:
58 */
59 unsigned int __read_mostly hardlockup_panic =
60 CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
61 /*
62 * We may not want to enable hard lockup detection by default in all cases,
63 * for example when running the kernel as a guest on a hypervisor. In these
64 * cases this function can be called to disable hard lockup detection. This
65 * function should only be executed once by the boot processor before the
66 * kernel command line parameters are parsed, because otherwise it is not
67 * possible to override this in hardlockup_panic_setup().
68 */
69 void __init hardlockup_detector_disable(void)
70 {
71 nmi_watchdog_user_enabled = 0;
72 }
73
74 static int __init hardlockup_panic_setup(char *str)
75 {
76 if (!strncmp(str, "panic", 5))
77 hardlockup_panic = 1;
78 else if (!strncmp(str, "nopanic", 7))
79 hardlockup_panic = 0;
80 else if (!strncmp(str, "", 1))
81 nmi_watchdog_user_enabled = 0;
82 else if (!strncmp(str, "1", 1))
83 nmi_watchdog_user_enabled = 1;
84 return 1;
85 }
86 __setup("nmi_watchdog=", hardlockup_panic_setup);
87
88 #endif /* CONFIG_HARDLOCKUP_DETECTOR */
89
90 /*
91 * These functions can be overridden if an architecture implements its
92 * own hardlockup detector.
93 *
94 * watchdog_nmi_enable/disable can be implemented to start and stop when
95 * softlockup watchdog threads start and stop. The arch must select the
96 * SOFTLOCKUP_DETECTOR Kconfig.
97 */
98 int __weak watchdog_nmi_enable(unsigned int cpu)
99 {
100 hardlockup_detector_perf_enable();
101 return 0;
102 }
103
104 void __weak watchdog_nmi_disable(unsigned int cpu)
105 {
106 hardlockup_detector_perf_disable();
107 }
108
109 /* Return 0, if a NMI watchdog is available. Error code otherwise */
110 int __weak __init watchdog_nmi_probe(void)
111 {
112 return hardlockup_detector_perf_init();
113 }
114
115 /**
116 * watchdog_nmi_stop - Stop the watchdog for reconfiguration
117 *
118 * The reconfiguration steps are:
119 * watchdog_nmi_stop();
120 * update_variables();
121 * watchdog_nmi_start();
122 */
123 void __weak watchdog_nmi_stop(void) { }
124
125 /**
126 * watchdog_nmi_start - Start the watchdog after reconfiguration
127 *
128 * Counterpart to watchdog_nmi_stop().
129 *
130 * The following variables have been updated in update_variables() and
131 * contain the currently valid configuration:
132 * - watchdog_enabled
133 * - watchdog_thresh
134 * - watchdog_cpumask
135 */
136 void __weak watchdog_nmi_start(void) { }
137
138 /**
139 * lockup_detector_update_enable - Update the sysctl enable bit
140 *
141 * Caller needs to make sure that the NMI/perf watchdogs are off, so this
142 * can't race with watchdog_nmi_disable().
143 */
144 static void lockup_detector_update_enable(void)
145 {
146 watchdog_enabled = 0;
147 if (!watchdog_user_enabled)
148 return;
149 if (nmi_watchdog_available && nmi_watchdog_user_enabled)
150 watchdog_enabled |= NMI_WATCHDOG_ENABLED;
151 if (soft_watchdog_user_enabled)
152 watchdog_enabled |= SOFT_WATCHDOG_ENABLED;
153 }
154
155 #ifdef CONFIG_SOFTLOCKUP_DETECTOR
156
157 /*
158 * Delay the soflockup report when running a known slow code.
159 * It does _not_ affect the timestamp of the last successdul reschedule.
160 */
161 #define SOFTLOCKUP_DELAY_REPORT ULONG_MAX
162
163 #ifdef CONFIG_SMP
164 int __read_mostly sysctl_softlockup_all_cpu_backtrace;
165 #endif
166
167 static struct cpumask watchdog_allowed_mask __read_mostly;
168
169 /* Global variables, exported for sysctl */
170 unsigned int __read_mostly softlockup_panic =
171 CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
172
173 static bool softlockup_initialized __read_mostly;
174 static u64 __read_mostly sample_period;
175
176 /* Timestamp taken after the last successful reschedule. */
177 static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
178 /* Timestamp of the last softlockup report. */
179 static DEFINE_PER_CPU(unsigned long, watchdog_report_ts);
180 static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer);
181 static DEFINE_PER_CPU(bool, softlockup_touch_sync);
182 static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);
183 static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);
184 static unsigned long soft_lockup_nmi_warn;
185
186 static int __init nowatchdog_setup(char *str)
187 {
188 watchdog_user_enabled = 0;
189 return 1;
190 }
191 __setup("nowatchdog", nowatchdog_setup);
192
193 static int __init nosoftlockup_setup(char *str)
194 {
195 soft_watchdog_user_enabled = 0;
196 return 1;
197 }
198 __setup("nosoftlockup", nosoftlockup_setup);
199
200 static int __init watchdog_thresh_setup(char *str)
201 {
202 get_option(&str, &watchdog_thresh);
203 return 1;
204 }
205 __setup("watchdog_thresh=", watchdog_thresh_setup);
206
207 static void __lockup_detector_cleanup(void);
208
209 /*
210 * Hard-lockup warnings should be triggered after just a few seconds. Soft-
211 * lockups can have false positives under extreme conditions. So we generally
212 * want a higher threshold for soft lockups than for hard lockups. So we couple
213 * the thresholds with a factor: we make the soft threshold twice the amount of
214 * time the hard threshold is.
215 */
216 static int get_softlockup_thresh(void)
217 {
218 return watchdog_thresh * 2;
219 }
220
221 /*
222 * Returns seconds, approximately. We don't need nanosecond
223 * resolution, and we don't need to waste time with a big divide when
224 * 2^30ns == 1.074s.
225 */
226 static unsigned long get_timestamp(void)
227 {
228 return running_clock() >> 30LL; /* 2^30 ~= 10^9 */
229 }
230
231 static void set_sample_period(void)
232 {
233 /*
234 * convert watchdog_thresh from seconds to ns
235 * the divide by 5 is to give hrtimer several chances (two
236 * or three with the current relation between the soft
237 * and hard thresholds) to increment before the
238 * hardlockup detector generates a warning
239 */
240 sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5);
241 watchdog_update_hrtimer_threshold(sample_period);
242 }
243
244 static void update_report_ts(void)
245 {
246 __this_cpu_write(watchdog_report_ts, get_timestamp());
247 }
248
249 /* Commands for resetting the watchdog */
250 static void update_touch_ts(void)
251 {
252 __this_cpu_write(watchdog_touch_ts, get_timestamp());
253 update_report_ts();
254 }
255
256 /**
257 * touch_softlockup_watchdog_sched - touch watchdog on scheduler stalls
258 *
259 * Call when the scheduler may have stalled for legitimate reasons
260 * preventing the watchdog task from executing - e.g. the scheduler
261 * entering idle state. This should only be used for scheduler events.
262 * Use touch_softlockup_watchdog() for everything else.
263 */
264 notrace void touch_softlockup_watchdog_sched(void)
265 {
266 /*
267 * Preemption can be enabled. It doesn't matter which CPU's watchdog
268 * report period gets restarted here, so use the raw_ operation.
269 */
270 raw_cpu_write(watchdog_report_ts, SOFTLOCKUP_DELAY_REPORT);
271 }
272
273 notrace void touch_softlockup_watchdog(void)
274 {
275 touch_softlockup_watchdog_sched();
276 wq_watchdog_touch(raw_smp_processor_id());
277 }
278 EXPORT_SYMBOL(touch_softlockup_watchdog);
279
280 void touch_all_softlockup_watchdogs(void)
281 {
282 int cpu;
283
284 /*
285 * watchdog_mutex cannpt be taken here, as this might be called
286 * from (soft)interrupt context, so the access to
287 * watchdog_allowed_cpumask might race with a concurrent update.
288 *
289 * The watchdog time stamp can race against a concurrent real
290 * update as well, the only side effect might be a cycle delay for
291 * the softlockup check.
292 */
293 for_each_cpu(cpu, &watchdog_allowed_mask) {
294 per_cpu(watchdog_report_ts, cpu) = SOFTLOCKUP_DELAY_REPORT;
295 wq_watchdog_touch(cpu);
296 }
297 }
298
299 void touch_softlockup_watchdog_sync(void)
300 {
301 __this_cpu_write(softlockup_touch_sync, true);
302 __this_cpu_write(watchdog_report_ts, SOFTLOCKUP_DELAY_REPORT);
303 }
304
305 static int is_softlockup(unsigned long touch_ts, unsigned long period_ts)
306 {
307 unsigned long now = get_timestamp();
308
309 if ((watchdog_enabled & SOFT_WATCHDOG_ENABLED) && watchdog_thresh){
310 /* Warn about unreasonable delays. */
311 if (time_after(now, period_ts + get_softlockup_thresh()))
312 return now - touch_ts;
313 }
314 return 0;
315 }
316
317 /* watchdog detector functions */
318 bool is_hardlockup(void)
319 {
320 unsigned long hrint = __this_cpu_read(hrtimer_interrupts);
321
322 if (__this_cpu_read(hrtimer_interrupts_saved) == hrint)
323 return true;
324
325 __this_cpu_write(hrtimer_interrupts_saved, hrint);
326 return false;
327 }
328
329 static void watchdog_interrupt_count(void)
330 {
331 __this_cpu_inc(hrtimer_interrupts);
332 }
333
334 static DEFINE_PER_CPU(struct completion, softlockup_completion);
335 static DEFINE_PER_CPU(struct cpu_stop_work, softlockup_stop_work);
336
337 /*
338 * The watchdog thread function - touches the timestamp.
339 *
340 * It only runs once every sample_period seconds (4 seconds by
341 * default) to reset the softlockup timestamp. If this gets delayed
342 * for more than 2*watchdog_thresh seconds then the debug-printout
343 * triggers in watchdog_timer_fn().
344 */
345 static int softlockup_fn(void *data)
346 {
347 update_touch_ts();
348 complete(this_cpu_ptr(&softlockup_completion));
349
350 return 0;
351 }
352
353 /* watchdog kicker functions */
354 static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
355 {
356 unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts);
357 unsigned long period_ts = __this_cpu_read(watchdog_report_ts);
358 struct pt_regs *regs = get_irq_regs();
359 int duration;
360 int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace;
361
362 if (!watchdog_enabled)
363 return HRTIMER_NORESTART;
364
365 /* kick the hardlockup detector */
366 watchdog_interrupt_count();
367
368 /* kick the softlockup detector */
369 if (completion_done(this_cpu_ptr(&softlockup_completion))) {
370 reinit_completion(this_cpu_ptr(&softlockup_completion));
371 stop_one_cpu_nowait(smp_processor_id(),
372 softlockup_fn, NULL,
373 this_cpu_ptr(&softlockup_stop_work));
374 }
375
376 /* .. and repeat */
377 hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period));
378
379 /* Reset the interval when touched externally by a known slow code. */
380 if (period_ts == SOFTLOCKUP_DELAY_REPORT) {
381 if (unlikely(__this_cpu_read(softlockup_touch_sync))) {
382 /*
383 * If the time stamp was touched atomically
384 * make sure the scheduler tick is up to date.
385 */
386 __this_cpu_write(softlockup_touch_sync, false);
387 sched_clock_tick();
388 }
389
390 /* Clear the guest paused flag on watchdog reset */
391 kvm_check_and_clear_guest_paused();
392 update_report_ts();
393
394 return HRTIMER_RESTART;
395 }
396
397 /* check for a softlockup
398 * This is done by making sure a high priority task is
399 * being scheduled. The task touches the watchdog to
400 * indicate it is getting cpu time. If it hasn't then
401 * this is a good indication some task is hogging the cpu
402 */
403 duration = is_softlockup(touch_ts, period_ts);
404 if (unlikely(duration)) {
405 /*
406 * If a virtual machine is stopped by the host it can look to
407 * the watchdog like a soft lockup, check to see if the host
408 * stopped the vm before we issue the warning
409 */
410 if (kvm_check_and_clear_guest_paused())
411 return HRTIMER_RESTART;
412
413 /*
414 * Prevent multiple soft-lockup reports if one cpu is already
415 * engaged in dumping all cpu back traces.
416 */
417 if (softlockup_all_cpu_backtrace) {
418 if (test_and_set_bit_lock(0, &soft_lockup_nmi_warn))
419 return HRTIMER_RESTART;
420 }
421
422 /* Start period for the next softlockup warning. */
423 update_report_ts();
424
425 pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
426 smp_processor_id(), duration,
427 current->comm, task_pid_nr(current));
428 print_modules();
429 print_irqtrace_events(current);
430 if (regs)
431 show_regs(regs);
432 else
433 dump_stack();
434
435 if (softlockup_all_cpu_backtrace) {
436 trigger_allbutself_cpu_backtrace();
437 clear_bit_unlock(0, &soft_lockup_nmi_warn);
438 }
439
440 add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK);
441 if (softlockup_panic)
442 panic("softlockup: hung tasks");
443 }
444
445 return HRTIMER_RESTART;
446 }
447
448 static void watchdog_enable(unsigned int cpu)
449 {
450 struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer);
451 struct completion *done = this_cpu_ptr(&softlockup_completion);
452
453 WARN_ON_ONCE(cpu != smp_processor_id());
454
455 init_completion(done);
456 complete(done);
457
458 /*
459 * Start the timer first to prevent the NMI watchdog triggering
460 * before the timer has a chance to fire.
461 */
462 hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
463 hrtimer->function = watchdog_timer_fn;
464 hrtimer_start(hrtimer, ns_to_ktime(sample_period),
465 HRTIMER_MODE_REL_PINNED_HARD);
466
467 /* Initialize timestamp */
468 update_touch_ts();
469 /* Enable the perf event */
470 if (watchdog_enabled & NMI_WATCHDOG_ENABLED)
471 watchdog_nmi_enable(cpu);
472 }
473
474 static void watchdog_disable(unsigned int cpu)
475 {
476 struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer);
477
478 WARN_ON_ONCE(cpu != smp_processor_id());
479
480 /*
481 * Disable the perf event first. That prevents that a large delay
482 * between disabling the timer and disabling the perf event causes
483 * the perf NMI to detect a false positive.
484 */
485 watchdog_nmi_disable(cpu);
486 hrtimer_cancel(hrtimer);
487 wait_for_completion(this_cpu_ptr(&softlockup_completion));
488 }
489
490 static int softlockup_stop_fn(void *data)
491 {
492 watchdog_disable(smp_processor_id());
493 return 0;
494 }
495
496 static void softlockup_stop_all(void)
497 {
498 int cpu;
499
500 if (!softlockup_initialized)
501 return;
502
503 for_each_cpu(cpu, &watchdog_allowed_mask)
504 smp_call_on_cpu(cpu, softlockup_stop_fn, NULL, false);
505
506 cpumask_clear(&watchdog_allowed_mask);
507 }
508
509 static int softlockup_start_fn(void *data)
510 {
511 watchdog_enable(smp_processor_id());
512 return 0;
513 }
514
515 static void softlockup_start_all(void)
516 {
517 int cpu;
518
519 cpumask_copy(&watchdog_allowed_mask, &watchdog_cpumask);
520 for_each_cpu(cpu, &watchdog_allowed_mask)
521 smp_call_on_cpu(cpu, softlockup_start_fn, NULL, false);
522 }
523
524 int lockup_detector_online_cpu(unsigned int cpu)
525 {
526 if (cpumask_test_cpu(cpu, &watchdog_allowed_mask))
527 watchdog_enable(cpu);
528 return 0;
529 }
530
531 int lockup_detector_offline_cpu(unsigned int cpu)
532 {
533 if (cpumask_test_cpu(cpu, &watchdog_allowed_mask))
534 watchdog_disable(cpu);
535 return 0;
536 }
537
538 static void lockup_detector_reconfigure(void)
539 {
540 cpus_read_lock();
541 watchdog_nmi_stop();
542
543 softlockup_stop_all();
544 set_sample_period();
545 lockup_detector_update_enable();
546 if (watchdog_enabled && watchdog_thresh)
547 softlockup_start_all();
548
549 watchdog_nmi_start();
550 cpus_read_unlock();
551 /*
552 * Must be called outside the cpus locked section to prevent
553 * recursive locking in the perf code.
554 */
555 __lockup_detector_cleanup();
556 }
557
558 /*
559 * Create the watchdog thread infrastructure and configure the detector(s).
560 *
561 * The threads are not unparked as watchdog_allowed_mask is empty. When
562 * the threads are successfully initialized, take the proper locks and
563 * unpark the threads in the watchdog_cpumask if the watchdog is enabled.
564 */
565 static __init void lockup_detector_setup(void)
566 {
567 /*
568 * If sysctl is off and watchdog got disabled on the command line,
569 * nothing to do here.
570 */
571 lockup_detector_update_enable();
572
573 if (!IS_ENABLED(CONFIG_SYSCTL) &&
574 !(watchdog_enabled && watchdog_thresh))
575 return;
576
577 mutex_lock(&watchdog_mutex);
578 lockup_detector_reconfigure();
579 softlockup_initialized = true;
580 mutex_unlock(&watchdog_mutex);
581 }
582
583 #else /* CONFIG_SOFTLOCKUP_DETECTOR */
584 static void lockup_detector_reconfigure(void)
585 {
586 cpus_read_lock();
587 watchdog_nmi_stop();
588 lockup_detector_update_enable();
589 watchdog_nmi_start();
590 cpus_read_unlock();
591 }
592 static inline void lockup_detector_setup(void)
593 {
594 lockup_detector_reconfigure();
595 }
596 #endif /* !CONFIG_SOFTLOCKUP_DETECTOR */
597
598 static void __lockup_detector_cleanup(void)
599 {
600 lockdep_assert_held(&watchdog_mutex);
601 hardlockup_detector_perf_cleanup();
602 }
603
604 /**
605 * lockup_detector_cleanup - Cleanup after cpu hotplug or sysctl changes
606 *
607 * Caller must not hold the cpu hotplug rwsem.
608 */
609 void lockup_detector_cleanup(void)
610 {
611 mutex_lock(&watchdog_mutex);
612 __lockup_detector_cleanup();
613 mutex_unlock(&watchdog_mutex);
614 }
615
616 /**
617 * lockup_detector_soft_poweroff - Interface to stop lockup detector(s)
618 *
619 * Special interface for parisc. It prevents lockup detector warnings from
620 * the default pm_poweroff() function which busy loops forever.
621 */
622 void lockup_detector_soft_poweroff(void)
623 {
624 watchdog_enabled = 0;
625 }
626
627 #ifdef CONFIG_SYSCTL
628
629 /* Propagate any changes to the watchdog threads */
630 static void proc_watchdog_update(void)
631 {
632 /* Remove impossible cpus to keep sysctl output clean. */
633 cpumask_and(&watchdog_cpumask, &watchdog_cpumask, cpu_possible_mask);
634 lockup_detector_reconfigure();
635 }
636
637 /*
638 * common function for watchdog, nmi_watchdog and soft_watchdog parameter
639 *
640 * caller | table->data points to | 'which'
641 * -------------------|----------------------------|--------------------------
642 * proc_watchdog | watchdog_user_enabled | NMI_WATCHDOG_ENABLED |
643 * | | SOFT_WATCHDOG_ENABLED
644 * -------------------|----------------------------|--------------------------
645 * proc_nmi_watchdog | nmi_watchdog_user_enabled | NMI_WATCHDOG_ENABLED
646 * -------------------|----------------------------|--------------------------
647 * proc_soft_watchdog | soft_watchdog_user_enabled | SOFT_WATCHDOG_ENABLED
648 */
649 static int proc_watchdog_common(int which, struct ctl_table *table, int write,
650 void *buffer, size_t *lenp, loff_t *ppos)
651 {
652 int err, old, *param = table->data;
653
654 mutex_lock(&watchdog_mutex);
655
656 if (!write) {
657 /*
658 * On read synchronize the userspace interface. This is a
659 * racy snapshot.
660 */
661 *param = (watchdog_enabled & which) != 0;
662 err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
663 } else {
664 old = READ_ONCE(*param);
665 err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
666 if (!err && old != READ_ONCE(*param))
667 proc_watchdog_update();
668 }
669 mutex_unlock(&watchdog_mutex);
670 return err;
671 }
672
673 /*
674 * /proc/sys/kernel/watchdog
675 */
676 int proc_watchdog(struct ctl_table *table, int write,
677 void *buffer, size_t *lenp, loff_t *ppos)
678 {
679 return proc_watchdog_common(NMI_WATCHDOG_ENABLED|SOFT_WATCHDOG_ENABLED,
680 table, write, buffer, lenp, ppos);
681 }
682
683 /*
684 * /proc/sys/kernel/nmi_watchdog
685 */
686 int proc_nmi_watchdog(struct ctl_table *table, int write,
687 void *buffer, size_t *lenp, loff_t *ppos)
688 {
689 if (!nmi_watchdog_available && write)
690 return -ENOTSUPP;
691 return proc_watchdog_common(NMI_WATCHDOG_ENABLED,
692 table, write, buffer, lenp, ppos);
693 }
694
695 /*
696 * /proc/sys/kernel/soft_watchdog
697 */
698 int proc_soft_watchdog(struct ctl_table *table, int write,
699 void *buffer, size_t *lenp, loff_t *ppos)
700 {
701 return proc_watchdog_common(SOFT_WATCHDOG_ENABLED,
702 table, write, buffer, lenp, ppos);
703 }
704
705 /*
706 * /proc/sys/kernel/watchdog_thresh
707 */
708 int proc_watchdog_thresh(struct ctl_table *table, int write,
709 void *buffer, size_t *lenp, loff_t *ppos)
710 {
711 int err, old;
712
713 mutex_lock(&watchdog_mutex);
714
715 old = READ_ONCE(watchdog_thresh);
716 err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
717
718 if (!err && write && old != READ_ONCE(watchdog_thresh))
719 proc_watchdog_update();
720
721 mutex_unlock(&watchdog_mutex);
722 return err;
723 }
724
725 /*
726 * The cpumask is the mask of possible cpus that the watchdog can run
727 * on, not the mask of cpus it is actually running on. This allows the
728 * user to specify a mask that will include cpus that have not yet
729 * been brought online, if desired.
730 */
731 int proc_watchdog_cpumask(struct ctl_table *table, int write,
732 void *buffer, size_t *lenp, loff_t *ppos)
733 {
734 int err;
735
736 mutex_lock(&watchdog_mutex);
737
738 err = proc_do_large_bitmap(table, write, buffer, lenp, ppos);
739 if (!err && write)
740 proc_watchdog_update();
741
742 mutex_unlock(&watchdog_mutex);
743 return err;
744 }
745 #endif /* CONFIG_SYSCTL */
746
747 void __init lockup_detector_init(void)
748 {
749 if (tick_nohz_full_enabled())
750 pr_info("Disabling watchdog on nohz_full cores by default\n");
751
752 cpumask_copy(&watchdog_cpumask,
753 housekeeping_cpumask(HK_FLAG_TIMER));
754
755 if (!watchdog_nmi_probe())
756 nmi_watchdog_available = true;
757 lockup_detector_setup();
758 }
759
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