watchdog: Change the default timeout and configure nmi watchdog period based on watch...
[linux-2.6.git] / kernel / watchdog.c
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 = 1;
31 int __read_mostly watchdog_thresh = 10;
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);
37 static DEFINE_PER_CPU(bool, soft_watchdog_warn);
38 #ifdef CONFIG_HARDLOCKUP_DETECTOR
39 static DEFINE_PER_CPU(bool, hard_watchdog_warn);
40 static DEFINE_PER_CPU(bool, watchdog_nmi_touch);
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
46 /* boot commands */
47 /*
48  * Should we panic when a soft-lockup or hard-lockup occurs:
49  */
50 #ifdef CONFIG_HARDLOCKUP_DETECTOR
51 static int hardlockup_panic =
52                         CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
53
54 static int __init hardlockup_panic_setup(char *str)
55 {
56         if (!strncmp(str, "panic", 5))
57                 hardlockup_panic = 1;
58         else if (!strncmp(str, "nopanic", 7))
59                 hardlockup_panic = 0;
60         else if (!strncmp(str, "0", 1))
61                 watchdog_enabled = 0;
62         return 1;
63 }
64 __setup("nmi_watchdog=", hardlockup_panic_setup);
65 #endif
66
67 unsigned int __read_mostly softlockup_panic =
68                         CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
69
70 static int __init softlockup_panic_setup(char *str)
71 {
72         softlockup_panic = simple_strtoul(str, NULL, 0);
73
74         return 1;
75 }
76 __setup("softlockup_panic=", softlockup_panic_setup);
77
78 static int __init nowatchdog_setup(char *str)
79 {
80         watchdog_enabled = 0;
81         return 1;
82 }
83 __setup("nowatchdog", nowatchdog_setup);
84
85 /* deprecated */
86 static int __init nosoftlockup_setup(char *str)
87 {
88         watchdog_enabled = 0;
89         return 1;
90 }
91 __setup("nosoftlockup", nosoftlockup_setup);
92 /*  */
93
94 /*
95  * Hard-lockup warnings should be triggered after just a few seconds. Soft-
96  * lockups can have false positives under extreme conditions. So we generally
97  * want a higher threshold for soft lockups than for hard lockups. So we couple
98  * the thresholds with a factor: we make the soft threshold twice the amount of
99  * time the hard threshold is.
100  */
101 static int get_softlockup_thresh()
102 {
103         return watchdog_thresh * 2;
104 }
105
106 /*
107  * Returns seconds, approximately.  We don't need nanosecond
108  * resolution, and we don't need to waste time with a big divide when
109  * 2^30ns == 1.074s.
110  */
111 static unsigned long get_timestamp(int this_cpu)
112 {
113         return cpu_clock(this_cpu) >> 30LL;  /* 2^30 ~= 10^9 */
114 }
115
116 static unsigned long get_sample_period(void)
117 {
118         /*
119          * convert watchdog_thresh from seconds to ns
120          * the divide by 5 is to give hrtimer 5 chances to
121          * increment before the hardlockup detector generates
122          * a warning
123          */
124         return get_softlockup_thresh() * (NSEC_PER_SEC / 5);
125 }
126
127 /* Commands for resetting the watchdog */
128 static void __touch_watchdog(void)
129 {
130         int this_cpu = smp_processor_id();
131
132         __this_cpu_write(watchdog_touch_ts, get_timestamp(this_cpu));
133 }
134
135 void touch_softlockup_watchdog(void)
136 {
137         __this_cpu_write(watchdog_touch_ts, 0);
138 }
139 EXPORT_SYMBOL(touch_softlockup_watchdog);
140
141 void touch_all_softlockup_watchdogs(void)
142 {
143         int cpu;
144
145         /*
146          * this is done lockless
147          * do we care if a 0 races with a timestamp?
148          * all it means is the softlock check starts one cycle later
149          */
150         for_each_online_cpu(cpu)
151                 per_cpu(watchdog_touch_ts, cpu) = 0;
152 }
153
154 #ifdef CONFIG_HARDLOCKUP_DETECTOR
155 void touch_nmi_watchdog(void)
156 {
157         if (watchdog_enabled) {
158                 unsigned cpu;
159
160                 for_each_present_cpu(cpu) {
161                         if (per_cpu(watchdog_nmi_touch, cpu) != true)
162                                 per_cpu(watchdog_nmi_touch, cpu) = true;
163                 }
164         }
165         touch_softlockup_watchdog();
166 }
167 EXPORT_SYMBOL(touch_nmi_watchdog);
168
169 #endif
170
171 void touch_softlockup_watchdog_sync(void)
172 {
173         __raw_get_cpu_var(softlockup_touch_sync) = true;
174         __raw_get_cpu_var(watchdog_touch_ts) = 0;
175 }
176
177 #ifdef CONFIG_HARDLOCKUP_DETECTOR
178 /* watchdog detector functions */
179 static int is_hardlockup(void)
180 {
181         unsigned long hrint = __this_cpu_read(hrtimer_interrupts);
182
183         if (__this_cpu_read(hrtimer_interrupts_saved) == hrint)
184                 return 1;
185
186         __this_cpu_write(hrtimer_interrupts_saved, hrint);
187         return 0;
188 }
189 #endif
190
191 static int is_softlockup(unsigned long touch_ts)
192 {
193         unsigned long now = get_timestamp(smp_processor_id());
194
195         /* Warn about unreasonable delays: */
196         if (time_after(now, touch_ts + get_softlockup_thresh()))
197                 return now - touch_ts;
198
199         return 0;
200 }
201
202 #ifdef CONFIG_HARDLOCKUP_DETECTOR
203 static struct perf_event_attr wd_hw_attr = {
204         .type           = PERF_TYPE_HARDWARE,
205         .config         = PERF_COUNT_HW_CPU_CYCLES,
206         .size           = sizeof(struct perf_event_attr),
207         .pinned         = 1,
208         .disabled       = 1,
209 };
210
211 /* Callback function for perf event subsystem */
212 static void watchdog_overflow_callback(struct perf_event *event, int nmi,
213                  struct perf_sample_data *data,
214                  struct pt_regs *regs)
215 {
216         /* Ensure the watchdog never gets throttled */
217         event->hw.interrupts = 0;
218
219         if (__this_cpu_read(watchdog_nmi_touch) == true) {
220                 __this_cpu_write(watchdog_nmi_touch, false);
221                 return;
222         }
223
224         /* check for a hardlockup
225          * This is done by making sure our timer interrupt
226          * is incrementing.  The timer interrupt should have
227          * fired multiple times before we overflow'd.  If it hasn't
228          * then this is a good indication the cpu is stuck
229          */
230         if (is_hardlockup()) {
231                 int this_cpu = smp_processor_id();
232
233                 /* only print hardlockups once */
234                 if (__this_cpu_read(hard_watchdog_warn) == true)
235                         return;
236
237                 if (hardlockup_panic)
238                         panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu);
239                 else
240                         WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu);
241
242                 __this_cpu_write(hard_watchdog_warn, true);
243                 return;
244         }
245
246         __this_cpu_write(hard_watchdog_warn, false);
247         return;
248 }
249 static void watchdog_interrupt_count(void)
250 {
251         __this_cpu_inc(hrtimer_interrupts);
252 }
253 #else
254 static inline void watchdog_interrupt_count(void) { return; }
255 #endif /* CONFIG_HARDLOCKUP_DETECTOR */
256
257 /* watchdog kicker functions */
258 static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
259 {
260         unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts);
261         struct pt_regs *regs = get_irq_regs();
262         int duration;
263
264         /* kick the hardlockup detector */
265         watchdog_interrupt_count();
266
267         /* kick the softlockup detector */
268         wake_up_process(__this_cpu_read(softlockup_watchdog));
269
270         /* .. and repeat */
271         hrtimer_forward_now(hrtimer, ns_to_ktime(get_sample_period()));
272
273         if (touch_ts == 0) {
274                 if (unlikely(__this_cpu_read(softlockup_touch_sync))) {
275                         /*
276                          * If the time stamp was touched atomically
277                          * make sure the scheduler tick is up to date.
278                          */
279                         __this_cpu_write(softlockup_touch_sync, false);
280                         sched_clock_tick();
281                 }
282                 __touch_watchdog();
283                 return HRTIMER_RESTART;
284         }
285
286         /* check for a softlockup
287          * This is done by making sure a high priority task is
288          * being scheduled.  The task touches the watchdog to
289          * indicate it is getting cpu time.  If it hasn't then
290          * this is a good indication some task is hogging the cpu
291          */
292         duration = is_softlockup(touch_ts);
293         if (unlikely(duration)) {
294                 /* only warn once */
295                 if (__this_cpu_read(soft_watchdog_warn) == true)
296                         return HRTIMER_RESTART;
297
298                 printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
299                         smp_processor_id(), duration,
300                         current->comm, task_pid_nr(current));
301                 print_modules();
302                 print_irqtrace_events(current);
303                 if (regs)
304                         show_regs(regs);
305                 else
306                         dump_stack();
307
308                 if (softlockup_panic)
309                         panic("softlockup: hung tasks");
310                 __this_cpu_write(soft_watchdog_warn, true);
311         } else
312                 __this_cpu_write(soft_watchdog_warn, false);
313
314         return HRTIMER_RESTART;
315 }
316
317
318 /*
319  * The watchdog thread - touches the timestamp.
320  */
321 static int watchdog(void *unused)
322 {
323         static struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
324         struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);
325
326         sched_setscheduler(current, SCHED_FIFO, &param);
327
328         /* initialize timestamp */
329         __touch_watchdog();
330
331         /* kick off the timer for the hardlockup detector */
332         /* done here because hrtimer_start can only pin to smp_processor_id() */
333         hrtimer_start(hrtimer, ns_to_ktime(get_sample_period()),
334                       HRTIMER_MODE_REL_PINNED);
335
336         set_current_state(TASK_INTERRUPTIBLE);
337         /*
338          * Run briefly once per second to reset the softlockup timestamp.
339          * If this gets delayed for more than 60 seconds then the
340          * debug-printout triggers in watchdog_timer_fn().
341          */
342         while (!kthread_should_stop()) {
343                 __touch_watchdog();
344                 schedule();
345
346                 if (kthread_should_stop())
347                         break;
348
349                 set_current_state(TASK_INTERRUPTIBLE);
350         }
351         __set_current_state(TASK_RUNNING);
352
353         return 0;
354 }
355
356
357 #ifdef CONFIG_HARDLOCKUP_DETECTOR
358 static int watchdog_nmi_enable(int cpu)
359 {
360         struct perf_event_attr *wd_attr;
361         struct perf_event *event = per_cpu(watchdog_ev, cpu);
362
363         /* is it already setup and enabled? */
364         if (event && event->state > PERF_EVENT_STATE_OFF)
365                 goto out;
366
367         /* it is setup but not enabled */
368         if (event != NULL)
369                 goto out_enable;
370
371         /* Try to register using hardware perf events */
372         wd_attr = &wd_hw_attr;
373         wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);
374         event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback);
375         if (!IS_ERR(event)) {
376                 printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");
377                 goto out_save;
378         }
379
380
381         /* vary the KERN level based on the returned errno */
382         if (PTR_ERR(event) == -EOPNOTSUPP)
383                 printk(KERN_INFO "NMI watchdog disabled (cpu%i): not supported (no LAPIC?)\n", cpu);
384         else if (PTR_ERR(event) == -ENOENT)
385                 printk(KERN_WARNING "NMI watchdog disabled (cpu%i): hardware events not enabled\n", cpu);
386         else
387                 printk(KERN_ERR "NMI watchdog disabled (cpu%i): unable to create perf event: %ld\n", cpu, PTR_ERR(event));
388         return PTR_ERR(event);
389
390         /* success path */
391 out_save:
392         per_cpu(watchdog_ev, cpu) = event;
393 out_enable:
394         perf_event_enable(per_cpu(watchdog_ev, cpu));
395 out:
396         return 0;
397 }
398
399 static void watchdog_nmi_disable(int cpu)
400 {
401         struct perf_event *event = per_cpu(watchdog_ev, cpu);
402
403         if (event) {
404                 perf_event_disable(event);
405                 per_cpu(watchdog_ev, cpu) = NULL;
406
407                 /* should be in cleanup, but blocks oprofile */
408                 perf_event_release_kernel(event);
409         }
410         return;
411 }
412 #else
413 static int watchdog_nmi_enable(int cpu) { return 0; }
414 static void watchdog_nmi_disable(int cpu) { return; }
415 #endif /* CONFIG_HARDLOCKUP_DETECTOR */
416
417 /* prepare/enable/disable routines */
418 static int watchdog_prepare_cpu(int cpu)
419 {
420         struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
421
422         WARN_ON(per_cpu(softlockup_watchdog, cpu));
423         hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
424         hrtimer->function = watchdog_timer_fn;
425
426         return 0;
427 }
428
429 static int watchdog_enable(int cpu)
430 {
431         struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
432         int err = 0;
433
434         /* enable the perf event */
435         err = watchdog_nmi_enable(cpu);
436
437         /* Regardless of err above, fall through and start softlockup */
438
439         /* create the watchdog thread */
440         if (!p) {
441                 p = kthread_create(watchdog, (void *)(unsigned long)cpu, "watchdog/%d", cpu);
442                 if (IS_ERR(p)) {
443                         printk(KERN_ERR "softlockup watchdog for %i failed\n", cpu);
444                         if (!err) {
445                                 /* if hardlockup hasn't already set this */
446                                 err = PTR_ERR(p);
447                                 /* and disable the perf event */
448                                 watchdog_nmi_disable(cpu);
449                         }
450                         goto out;
451                 }
452                 kthread_bind(p, cpu);
453                 per_cpu(watchdog_touch_ts, cpu) = 0;
454                 per_cpu(softlockup_watchdog, cpu) = p;
455                 wake_up_process(p);
456         }
457
458 out:
459         return err;
460 }
461
462 static void watchdog_disable(int cpu)
463 {
464         struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
465         struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
466
467         /*
468          * cancel the timer first to stop incrementing the stats
469          * and waking up the kthread
470          */
471         hrtimer_cancel(hrtimer);
472
473         /* disable the perf event */
474         watchdog_nmi_disable(cpu);
475
476         /* stop the watchdog thread */
477         if (p) {
478                 per_cpu(softlockup_watchdog, cpu) = NULL;
479                 kthread_stop(p);
480         }
481 }
482
483 static void watchdog_enable_all_cpus(void)
484 {
485         int cpu;
486
487         watchdog_enabled = 0;
488
489         for_each_online_cpu(cpu)
490                 if (!watchdog_enable(cpu))
491                         /* if any cpu succeeds, watchdog is considered
492                            enabled for the system */
493                         watchdog_enabled = 1;
494
495         if (!watchdog_enabled)
496                 printk(KERN_ERR "watchdog: failed to be enabled on some cpus\n");
497
498 }
499
500 static void watchdog_disable_all_cpus(void)
501 {
502         int cpu;
503
504         for_each_online_cpu(cpu)
505                 watchdog_disable(cpu);
506
507         /* if all watchdogs are disabled, then they are disabled for the system */
508         watchdog_enabled = 0;
509 }
510
511
512 /* sysctl functions */
513 #ifdef CONFIG_SYSCTL
514 /*
515  * proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh
516  */
517
518 int proc_dowatchdog(struct ctl_table *table, int write,
519                     void __user *buffer, size_t *lenp, loff_t *ppos)
520 {
521         int ret;
522
523         ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
524         if (ret || !write)
525                 goto out;
526
527         if (watchdog_enabled && watchdog_thresh)
528                 watchdog_enable_all_cpus();
529         else
530                 watchdog_disable_all_cpus();
531
532 out:
533         return ret;
534 }
535 #endif /* CONFIG_SYSCTL */
536
537
538 /*
539  * Create/destroy watchdog threads as CPUs come and go:
540  */
541 static int __cpuinit
542 cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
543 {
544         int hotcpu = (unsigned long)hcpu;
545         int err = 0;
546
547         switch (action) {
548         case CPU_UP_PREPARE:
549         case CPU_UP_PREPARE_FROZEN:
550                 err = watchdog_prepare_cpu(hotcpu);
551                 break;
552         case CPU_ONLINE:
553         case CPU_ONLINE_FROZEN:
554                 if (watchdog_enabled)
555                         err = watchdog_enable(hotcpu);
556                 break;
557 #ifdef CONFIG_HOTPLUG_CPU
558         case CPU_UP_CANCELED:
559         case CPU_UP_CANCELED_FROZEN:
560                 watchdog_disable(hotcpu);
561                 break;
562         case CPU_DEAD:
563         case CPU_DEAD_FROZEN:
564                 watchdog_disable(hotcpu);
565                 break;
566 #endif /* CONFIG_HOTPLUG_CPU */
567         }
568
569         /*
570          * hardlockup and softlockup are not important enough
571          * to block cpu bring up.  Just always succeed and
572          * rely on printk output to flag problems.
573          */
574         return NOTIFY_OK;
575 }
576
577 static struct notifier_block __cpuinitdata cpu_nfb = {
578         .notifier_call = cpu_callback
579 };
580
581 void __init lockup_detector_init(void)
582 {
583         void *cpu = (void *)(long)smp_processor_id();
584         int err;
585
586         err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
587         WARN_ON(notifier_to_errno(err));
588
589         cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
590         register_cpu_notifier(&cpu_nfb);
591
592         return;
593 }