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10
11
12#define pr_fmt(fmt) "NMI watchdog: " fmt
13
14#include <linux/mm.h>
15#include <linux/cpu.h>
16#include <linux/nmi.h>
17#include <linux/init.h>
18#include <linux/module.h>
19#include <linux/sysctl.h>
20#include <linux/smpboot.h>
21#include <linux/sched/rt.h>
22#include <linux/tick.h>
23#include <linux/workqueue.h>
24
25#include <asm/irq_regs.h>
26#include <linux/kvm_para.h>
27#include <linux/perf_event.h>
28#include <linux/kthread.h>
29
30
31
32
33
34
35
36
37
38
39
40
41
42#define NMI_WATCHDOG_ENABLED_BIT 0
43#define SOFT_WATCHDOG_ENABLED_BIT 1
44#define NMI_WATCHDOG_ENABLED (1 << NMI_WATCHDOG_ENABLED_BIT)
45#define SOFT_WATCHDOG_ENABLED (1 << SOFT_WATCHDOG_ENABLED_BIT)
46
47static DEFINE_MUTEX(watchdog_proc_mutex);
48
49#ifdef CONFIG_HARDLOCKUP_DETECTOR
50static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED;
51#else
52static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED;
53#endif
54int __read_mostly nmi_watchdog_enabled;
55int __read_mostly soft_watchdog_enabled;
56int __read_mostly watchdog_user_enabled;
57int __read_mostly watchdog_thresh = 10;
58
59#ifdef CONFIG_SMP
60int __read_mostly sysctl_softlockup_all_cpu_backtrace;
61int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
62#else
63#define sysctl_softlockup_all_cpu_backtrace 0
64#define sysctl_hardlockup_all_cpu_backtrace 0
65#endif
66static struct cpumask watchdog_cpumask __read_mostly;
67unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask);
68
69
70#define for_each_watchdog_cpu(cpu) \
71 for_each_cpu_and((cpu), cpu_online_mask, &watchdog_cpumask)
72
73
74
75
76
77
78static int __read_mostly watchdog_running;
79
80
81
82
83
84
85
86
87
88
89
90
91static int __read_mostly watchdog_suspended;
92
93static u64 __read_mostly sample_period;
94
95static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
96static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
97static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer);
98static DEFINE_PER_CPU(bool, softlockup_touch_sync);
99static DEFINE_PER_CPU(bool, soft_watchdog_warn);
100static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);
101static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt);
102static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved);
103#ifdef CONFIG_HARDLOCKUP_DETECTOR
104static DEFINE_PER_CPU(bool, hard_watchdog_warn);
105static DEFINE_PER_CPU(bool, watchdog_nmi_touch);
106static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);
107static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
108#endif
109static unsigned long soft_lockup_nmi_warn;
110
111
112
113
114
115#ifdef CONFIG_HARDLOCKUP_DETECTOR
116unsigned int __read_mostly hardlockup_panic =
117 CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
118static unsigned long hardlockup_allcpu_dumped;
119
120
121
122
123
124
125
126
127void hardlockup_detector_disable(void)
128{
129 watchdog_enabled &= ~NMI_WATCHDOG_ENABLED;
130}
131
132static int __init hardlockup_panic_setup(char *str)
133{
134 if (!strncmp(str, "panic", 5))
135 hardlockup_panic = 1;
136 else if (!strncmp(str, "nopanic", 7))
137 hardlockup_panic = 0;
138 else if (!strncmp(str, "0", 1))
139 watchdog_enabled &= ~NMI_WATCHDOG_ENABLED;
140 else if (!strncmp(str, "1", 1))
141 watchdog_enabled |= NMI_WATCHDOG_ENABLED;
142 return 1;
143}
144__setup("nmi_watchdog=", hardlockup_panic_setup);
145#endif
146
147unsigned int __read_mostly softlockup_panic =
148 CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
149
150static int __init softlockup_panic_setup(char *str)
151{
152 softlockup_panic = simple_strtoul(str, NULL, 0);
153
154 return 1;
155}
156__setup("softlockup_panic=", softlockup_panic_setup);
157
158static int __init nowatchdog_setup(char *str)
159{
160 watchdog_enabled = 0;
161 return 1;
162}
163__setup("nowatchdog", nowatchdog_setup);
164
165static int __init nosoftlockup_setup(char *str)
166{
167 watchdog_enabled &= ~SOFT_WATCHDOG_ENABLED;
168 return 1;
169}
170__setup("nosoftlockup", nosoftlockup_setup);
171
172#ifdef CONFIG_SMP
173static int __init softlockup_all_cpu_backtrace_setup(char *str)
174{
175 sysctl_softlockup_all_cpu_backtrace =
176 !!simple_strtol(str, NULL, 0);
177 return 1;
178}
179__setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup);
180static int __init hardlockup_all_cpu_backtrace_setup(char *str)
181{
182 sysctl_hardlockup_all_cpu_backtrace =
183 !!simple_strtol(str, NULL, 0);
184 return 1;
185}
186__setup("hardlockup_all_cpu_backtrace=", hardlockup_all_cpu_backtrace_setup);
187#endif
188
189
190
191
192
193
194
195
196static int get_softlockup_thresh(void)
197{
198 return watchdog_thresh * 2;
199}
200
201
202
203
204
205
206static unsigned long get_timestamp(void)
207{
208 return running_clock() >> 30LL;
209}
210
211static void set_sample_period(void)
212{
213
214
215
216
217
218
219
220 sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5);
221}
222
223
224static void __touch_watchdog(void)
225{
226 __this_cpu_write(watchdog_touch_ts, get_timestamp());
227}
228
229
230
231
232
233
234
235
236
237void touch_softlockup_watchdog_sched(void)
238{
239
240
241
242
243 raw_cpu_write(watchdog_touch_ts, 0);
244}
245
246void touch_softlockup_watchdog(void)
247{
248 touch_softlockup_watchdog_sched();
249 wq_watchdog_touch(raw_smp_processor_id());
250}
251EXPORT_SYMBOL(touch_softlockup_watchdog);
252
253void touch_all_softlockup_watchdogs(void)
254{
255 int cpu;
256
257
258
259
260
261
262 for_each_watchdog_cpu(cpu)
263 per_cpu(watchdog_touch_ts, cpu) = 0;
264 wq_watchdog_touch(-1);
265}
266
267#ifdef CONFIG_HARDLOCKUP_DETECTOR
268void touch_nmi_watchdog(void)
269{
270
271
272
273
274
275
276
277 raw_cpu_write(watchdog_nmi_touch, true);
278 touch_softlockup_watchdog();
279}
280EXPORT_SYMBOL(touch_nmi_watchdog);
281
282#endif
283
284void touch_softlockup_watchdog_sync(void)
285{
286 __this_cpu_write(softlockup_touch_sync, true);
287 __this_cpu_write(watchdog_touch_ts, 0);
288}
289
290#ifdef CONFIG_HARDLOCKUP_DETECTOR
291
292static bool is_hardlockup(void)
293{
294 unsigned long hrint = __this_cpu_read(hrtimer_interrupts);
295
296 if (__this_cpu_read(hrtimer_interrupts_saved) == hrint)
297 return true;
298
299 __this_cpu_write(hrtimer_interrupts_saved, hrint);
300 return false;
301}
302#endif
303
304static int is_softlockup(unsigned long touch_ts)
305{
306 unsigned long now = get_timestamp();
307
308 if ((watchdog_enabled & SOFT_WATCHDOG_ENABLED) && watchdog_thresh){
309
310 if (time_after(now, touch_ts + get_softlockup_thresh()))
311 return now - touch_ts;
312 }
313 return 0;
314}
315
316#ifdef CONFIG_HARDLOCKUP_DETECTOR
317
318static struct perf_event_attr wd_hw_attr = {
319 .type = PERF_TYPE_HARDWARE,
320 .config = PERF_COUNT_HW_CPU_CYCLES,
321 .size = sizeof(struct perf_event_attr),
322 .pinned = 1,
323 .disabled = 1,
324};
325
326
327static void watchdog_overflow_callback(struct perf_event *event,
328 struct perf_sample_data *data,
329 struct pt_regs *regs)
330{
331
332 event->hw.interrupts = 0;
333
334 if (__this_cpu_read(watchdog_nmi_touch) == true) {
335 __this_cpu_write(watchdog_nmi_touch, false);
336 return;
337 }
338
339
340
341
342
343
344
345 if (is_hardlockup()) {
346 int this_cpu = smp_processor_id();
347 struct pt_regs *regs = get_irq_regs();
348
349
350 if (__this_cpu_read(hard_watchdog_warn) == true)
351 return;
352
353 pr_emerg("Watchdog detected hard LOCKUP on cpu %d", this_cpu);
354 print_modules();
355 print_irqtrace_events(current);
356 if (regs)
357 show_regs(regs);
358 else
359 dump_stack();
360
361
362
363
364
365 if (sysctl_hardlockup_all_cpu_backtrace &&
366 !test_and_set_bit(0, &hardlockup_allcpu_dumped))
367 trigger_allbutself_cpu_backtrace();
368
369 if (hardlockup_panic)
370 nmi_panic(regs, "Hard LOCKUP");
371
372 __this_cpu_write(hard_watchdog_warn, true);
373 return;
374 }
375
376 __this_cpu_write(hard_watchdog_warn, false);
377 return;
378}
379#endif
380
381static void watchdog_interrupt_count(void)
382{
383 __this_cpu_inc(hrtimer_interrupts);
384}
385
386static int watchdog_nmi_enable(unsigned int cpu);
387static void watchdog_nmi_disable(unsigned int cpu);
388
389static int watchdog_enable_all_cpus(void);
390static void watchdog_disable_all_cpus(void);
391
392
393static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
394{
395 unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts);
396 struct pt_regs *regs = get_irq_regs();
397 int duration;
398 int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace;
399
400
401 watchdog_interrupt_count();
402
403
404 wake_up_process(__this_cpu_read(softlockup_watchdog));
405
406
407 hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period));
408
409 if (touch_ts == 0) {
410 if (unlikely(__this_cpu_read(softlockup_touch_sync))) {
411
412
413
414
415 __this_cpu_write(softlockup_touch_sync, false);
416 sched_clock_tick();
417 }
418
419
420 kvm_check_and_clear_guest_paused();
421 __touch_watchdog();
422 return HRTIMER_RESTART;
423 }
424
425
426
427
428
429
430
431 duration = is_softlockup(touch_ts);
432 if (unlikely(duration)) {
433
434
435
436
437
438 if (kvm_check_and_clear_guest_paused())
439 return HRTIMER_RESTART;
440
441
442 if (__this_cpu_read(soft_watchdog_warn) == true) {
443
444
445
446
447
448
449
450
451 if (__this_cpu_read(softlockup_task_ptr_saved) !=
452 current) {
453 __this_cpu_write(soft_watchdog_warn, false);
454 __touch_watchdog();
455 }
456 return HRTIMER_RESTART;
457 }
458
459 if (softlockup_all_cpu_backtrace) {
460
461
462
463 if (test_and_set_bit(0, &soft_lockup_nmi_warn)) {
464
465 __this_cpu_write(soft_watchdog_warn, true);
466 return HRTIMER_RESTART;
467 }
468 }
469
470 pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
471 smp_processor_id(), duration,
472 current->comm, task_pid_nr(current));
473 __this_cpu_write(softlockup_task_ptr_saved, current);
474 print_modules();
475 print_irqtrace_events(current);
476 if (regs)
477 show_regs(regs);
478 else
479 dump_stack();
480
481 if (softlockup_all_cpu_backtrace) {
482
483
484
485 trigger_allbutself_cpu_backtrace();
486
487 clear_bit(0, &soft_lockup_nmi_warn);
488
489 smp_mb__after_atomic();
490 }
491
492 add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK);
493 if (softlockup_panic)
494 panic("softlockup: hung tasks");
495 __this_cpu_write(soft_watchdog_warn, true);
496 } else
497 __this_cpu_write(soft_watchdog_warn, false);
498
499 return HRTIMER_RESTART;
500}
501
502static void watchdog_set_prio(unsigned int policy, unsigned int prio)
503{
504 struct sched_param param = { .sched_priority = prio };
505
506 sched_setscheduler(current, policy, ¶m);
507}
508
509static void watchdog_enable(unsigned int cpu)
510{
511 struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer);
512
513
514 hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
515 hrtimer->function = watchdog_timer_fn;
516
517
518 watchdog_nmi_enable(cpu);
519
520
521 hrtimer_start(hrtimer, ns_to_ktime(sample_period),
522 HRTIMER_MODE_REL_PINNED);
523
524
525 watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1);
526 __touch_watchdog();
527}
528
529static void watchdog_disable(unsigned int cpu)
530{
531 struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer);
532
533 watchdog_set_prio(SCHED_NORMAL, 0);
534 hrtimer_cancel(hrtimer);
535
536 watchdog_nmi_disable(cpu);
537}
538
539static void watchdog_cleanup(unsigned int cpu, bool online)
540{
541 watchdog_disable(cpu);
542}
543
544static int watchdog_should_run(unsigned int cpu)
545{
546 return __this_cpu_read(hrtimer_interrupts) !=
547 __this_cpu_read(soft_lockup_hrtimer_cnt);
548}
549
550
551
552
553
554
555
556
557
558static void watchdog(unsigned int cpu)
559{
560 __this_cpu_write(soft_lockup_hrtimer_cnt,
561 __this_cpu_read(hrtimer_interrupts));
562 __touch_watchdog();
563
564
565
566
567
568
569
570
571
572
573
574
575
576 if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))
577 watchdog_nmi_disable(cpu);
578}
579
580#ifdef CONFIG_HARDLOCKUP_DETECTOR
581
582
583
584
585
586static unsigned long cpu0_err;
587
588static int watchdog_nmi_enable(unsigned int cpu)
589{
590 struct perf_event_attr *wd_attr;
591 struct perf_event *event = per_cpu(watchdog_ev, cpu);
592
593
594 if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))
595 goto out;
596
597
598 if (event && event->state > PERF_EVENT_STATE_OFF)
599 goto out;
600
601
602 if (event != NULL)
603 goto out_enable;
604
605 wd_attr = &wd_hw_attr;
606 wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);
607
608
609 event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL);
610
611
612 if (cpu == 0 && IS_ERR(event))
613 cpu0_err = PTR_ERR(event);
614
615 if (!IS_ERR(event)) {
616
617 if (cpu == 0 || cpu0_err)
618 pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n");
619 goto out_save;
620 }
621
622
623
624
625
626
627
628
629
630 smp_mb__before_atomic();
631 clear_bit(NMI_WATCHDOG_ENABLED_BIT, &watchdog_enabled);
632 smp_mb__after_atomic();
633
634
635 if (cpu > 0 && (PTR_ERR(event) == cpu0_err))
636 return PTR_ERR(event);
637
638
639 if (PTR_ERR(event) == -EOPNOTSUPP)
640 pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu);
641 else if (PTR_ERR(event) == -ENOENT)
642 pr_warn("disabled (cpu%i): hardware events not enabled\n",
643 cpu);
644 else
645 pr_err("disabled (cpu%i): unable to create perf event: %ld\n",
646 cpu, PTR_ERR(event));
647
648 pr_info("Shutting down hard lockup detector on all cpus\n");
649
650 return PTR_ERR(event);
651
652
653out_save:
654 per_cpu(watchdog_ev, cpu) = event;
655out_enable:
656 perf_event_enable(per_cpu(watchdog_ev, cpu));
657out:
658 return 0;
659}
660
661static void watchdog_nmi_disable(unsigned int cpu)
662{
663 struct perf_event *event = per_cpu(watchdog_ev, cpu);
664
665 if (event) {
666 perf_event_disable(event);
667 per_cpu(watchdog_ev, cpu) = NULL;
668
669
670 perf_event_release_kernel(event);
671 }
672 if (cpu == 0) {
673
674 cpu0_err = 0;
675 }
676}
677
678#else
679static int watchdog_nmi_enable(unsigned int cpu) { return 0; }
680static void watchdog_nmi_disable(unsigned int cpu) { return; }
681#endif
682
683static struct smp_hotplug_thread watchdog_threads = {
684 .store = &softlockup_watchdog,
685 .thread_should_run = watchdog_should_run,
686 .thread_fn = watchdog,
687 .thread_comm = "watchdog/%u",
688 .setup = watchdog_enable,
689 .cleanup = watchdog_cleanup,
690 .park = watchdog_disable,
691 .unpark = watchdog_enable,
692};
693
694
695
696
697
698
699
700
701
702
703
704
705
706static int watchdog_park_threads(void)
707{
708 int cpu, ret = 0;
709
710 for_each_watchdog_cpu(cpu) {
711 ret = kthread_park(per_cpu(softlockup_watchdog, cpu));
712 if (ret)
713 break;
714 }
715
716 return ret;
717}
718
719
720
721
722
723
724
725static void watchdog_unpark_threads(void)
726{
727 int cpu;
728
729 for_each_watchdog_cpu(cpu)
730 kthread_unpark(per_cpu(softlockup_watchdog, cpu));
731}
732
733
734
735
736int lockup_detector_suspend(void)
737{
738 int ret = 0;
739
740 get_online_cpus();
741 mutex_lock(&watchdog_proc_mutex);
742
743
744
745
746
747
748
749 if (watchdog_running && !watchdog_suspended)
750 ret = watchdog_park_threads();
751
752 if (ret == 0)
753 watchdog_suspended++;
754 else {
755 watchdog_disable_all_cpus();
756 pr_err("Failed to suspend lockup detectors, disabled\n");
757 watchdog_enabled = 0;
758 }
759
760 mutex_unlock(&watchdog_proc_mutex);
761
762 return ret;
763}
764
765
766
767
768void lockup_detector_resume(void)
769{
770 mutex_lock(&watchdog_proc_mutex);
771
772 watchdog_suspended--;
773
774
775
776
777 if (watchdog_running && !watchdog_suspended)
778 watchdog_unpark_threads();
779
780 mutex_unlock(&watchdog_proc_mutex);
781 put_online_cpus();
782}
783
784static int update_watchdog_all_cpus(void)
785{
786 int ret;
787
788 ret = watchdog_park_threads();
789 if (ret)
790 return ret;
791
792 watchdog_unpark_threads();
793
794 return 0;
795}
796
797static int watchdog_enable_all_cpus(void)
798{
799 int err = 0;
800
801 if (!watchdog_running) {
802 err = smpboot_register_percpu_thread_cpumask(&watchdog_threads,
803 &watchdog_cpumask);
804 if (err)
805 pr_err("Failed to create watchdog threads, disabled\n");
806 else
807 watchdog_running = 1;
808 } else {
809
810
811
812
813 err = update_watchdog_all_cpus();
814
815 if (err) {
816 watchdog_disable_all_cpus();
817 pr_err("Failed to update lockup detectors, disabled\n");
818 }
819 }
820
821 if (err)
822 watchdog_enabled = 0;
823
824 return err;
825}
826
827static void watchdog_disable_all_cpus(void)
828{
829 if (watchdog_running) {
830 watchdog_running = 0;
831 smpboot_unregister_percpu_thread(&watchdog_threads);
832 }
833}
834
835#ifdef CONFIG_SYSCTL
836
837
838
839
840static int proc_watchdog_update(void)
841{
842 int err = 0;
843
844
845
846
847
848
849
850
851 if (watchdog_enabled && watchdog_thresh)
852 err = watchdog_enable_all_cpus();
853 else
854 watchdog_disable_all_cpus();
855
856 return err;
857
858}
859
860
861
862
863
864
865
866
867
868
869
870
871
872static int proc_watchdog_common(int which, struct ctl_table *table, int write,
873 void __user *buffer, size_t *lenp, loff_t *ppos)
874{
875 int err, old, new;
876 int *watchdog_param = (int *)table->data;
877
878 get_online_cpus();
879 mutex_lock(&watchdog_proc_mutex);
880
881 if (watchdog_suspended) {
882
883 err = -EAGAIN;
884 goto out;
885 }
886
887
888
889
890
891
892 if (!write) {
893 *watchdog_param = (watchdog_enabled & which) != 0;
894 err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
895 } else {
896 err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
897 if (err)
898 goto out;
899
900
901
902
903
904
905
906
907 do {
908 old = watchdog_enabled;
909
910
911
912
913 if (*watchdog_param)
914 new = old | which;
915 else
916 new = old & ~which;
917 } while (cmpxchg(&watchdog_enabled, old, new) != old);
918
919
920
921
922
923
924
925
926 if (old == new)
927 goto out;
928
929 err = proc_watchdog_update();
930 }
931out:
932 mutex_unlock(&watchdog_proc_mutex);
933 put_online_cpus();
934 return err;
935}
936
937
938
939
940int proc_watchdog(struct ctl_table *table, int write,
941 void __user *buffer, size_t *lenp, loff_t *ppos)
942{
943 return proc_watchdog_common(NMI_WATCHDOG_ENABLED|SOFT_WATCHDOG_ENABLED,
944 table, write, buffer, lenp, ppos);
945}
946
947
948
949
950int proc_nmi_watchdog(struct ctl_table *table, int write,
951 void __user *buffer, size_t *lenp, loff_t *ppos)
952{
953 return proc_watchdog_common(NMI_WATCHDOG_ENABLED,
954 table, write, buffer, lenp, ppos);
955}
956
957
958
959
960int proc_soft_watchdog(struct ctl_table *table, int write,
961 void __user *buffer, size_t *lenp, loff_t *ppos)
962{
963 return proc_watchdog_common(SOFT_WATCHDOG_ENABLED,
964 table, write, buffer, lenp, ppos);
965}
966
967
968
969
970int proc_watchdog_thresh(struct ctl_table *table, int write,
971 void __user *buffer, size_t *lenp, loff_t *ppos)
972{
973 int err, old, new;
974
975 get_online_cpus();
976 mutex_lock(&watchdog_proc_mutex);
977
978 if (watchdog_suspended) {
979
980 err = -EAGAIN;
981 goto out;
982 }
983
984 old = ACCESS_ONCE(watchdog_thresh);
985 err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
986
987 if (err || !write)
988 goto out;
989
990
991
992
993 new = ACCESS_ONCE(watchdog_thresh);
994 if (old == new)
995 goto out;
996
997 set_sample_period();
998 err = proc_watchdog_update();
999 if (err) {
1000 watchdog_thresh = old;
1001 set_sample_period();
1002 }
1003out:
1004 mutex_unlock(&watchdog_proc_mutex);
1005 put_online_cpus();
1006 return err;
1007}
1008
1009
1010
1011
1012
1013
1014
1015int proc_watchdog_cpumask(struct ctl_table *table, int write,
1016 void __user *buffer, size_t *lenp, loff_t *ppos)
1017{
1018 int err;
1019
1020 get_online_cpus();
1021 mutex_lock(&watchdog_proc_mutex);
1022
1023 if (watchdog_suspended) {
1024
1025 err = -EAGAIN;
1026 goto out;
1027 }
1028
1029 err = proc_do_large_bitmap(table, write, buffer, lenp, ppos);
1030 if (!err && write) {
1031
1032 cpumask_and(&watchdog_cpumask, &watchdog_cpumask,
1033 cpu_possible_mask);
1034
1035 if (watchdog_running) {
1036
1037
1038
1039
1040
1041 if (smpboot_update_cpumask_percpu_thread(
1042 &watchdog_threads, &watchdog_cpumask) != 0)
1043 pr_err("cpumask update failed\n");
1044 }
1045 }
1046out:
1047 mutex_unlock(&watchdog_proc_mutex);
1048 put_online_cpus();
1049 return err;
1050}
1051
1052#endif
1053
1054void __init lockup_detector_init(void)
1055{
1056 set_sample_period();
1057
1058#ifdef CONFIG_NO_HZ_FULL
1059 if (tick_nohz_full_enabled()) {
1060 pr_info("Disabling watchdog on nohz_full cores by default\n");
1061 cpumask_copy(&watchdog_cpumask, housekeeping_mask);
1062 } else
1063 cpumask_copy(&watchdog_cpumask, cpu_possible_mask);
1064#else
1065 cpumask_copy(&watchdog_cpumask, cpu_possible_mask);
1066#endif
1067
1068 if (watchdog_enabled)
1069 watchdog_enable_all_cpus();
1070}
1071