lockup_detector: Combine nmi_watchdog and softlockup detector
[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;
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);
37 static DEFINE_PER_CPU(bool, hard_watchdog_warn);
38 static DEFINE_PER_CPU(bool, soft_watchdog_warn);
39 #ifdef CONFIG_PERF_EVENTS_NMI
40 static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);
41 static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);
42 static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
43 #endif
44
45 static int __read_mostly did_panic;
46 static int __initdata no_watchdog;
47
48
49 /* boot commands */
50 /*
51  * Should we panic when a soft-lockup or hard-lockup occurs:
52  */
53 #ifdef CONFIG_PERF_EVENTS_NMI
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 {
117         int this_cpu = raw_smp_processor_id();
118
119         __get_cpu_var(watchdog_touch_ts) = get_timestamp(this_cpu);
120 }
121
122 void touch_watchdog(void)
123 {
124         __get_cpu_var(watchdog_touch_ts) = 0;
125 }
126 EXPORT_SYMBOL(touch_watchdog);
127
128 void touch_all_watchdog(void)
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
141 void touch_nmi_watchdog(void)
142 {
143         touch_watchdog();
144 }
145 EXPORT_SYMBOL(touch_nmi_watchdog);
146
147 void touch_all_nmi_watchdog(void)
148 {
149         touch_all_watchdog();
150 }
151
152 void touch_softlockup_watchdog(void)
153 {
154         touch_watchdog();
155 }
156
157 void touch_all_softlockup_watchdogs(void)
158 {
159         touch_all_watchdog();
160 }
161
162 void touch_softlockup_watchdog_sync(void)
163 {
164         __raw_get_cpu_var(softlockup_touch_sync) = true;
165         __raw_get_cpu_var(watchdog_touch_ts) = 0;
166 }
167
168 void softlockup_tick(void)
169 {
170 }
171
172 #ifdef CONFIG_PERF_EVENTS_NMI
173 /* watchdog detector functions */
174 static int is_hardlockup(int cpu)
175 {
176         unsigned long hrint = per_cpu(hrtimer_interrupts, cpu);
177
178         if (per_cpu(hrtimer_interrupts_saved, cpu) == hrint)
179                 return 1;
180
181         per_cpu(hrtimer_interrupts_saved, cpu) = hrint;
182         return 0;
183 }
184 #endif
185
186 static int is_softlockup(unsigned long touch_ts, int cpu)
187 {
188         unsigned long now = get_timestamp(cpu);
189
190         /* Warn about unreasonable delays: */
191         if (time_after(now, touch_ts + softlockup_thresh))
192                 return now - touch_ts;
193
194         return 0;
195 }
196
197 static int
198 watchdog_panic(struct notifier_block *this, unsigned long event, void *ptr)
199 {
200         did_panic = 1;
201
202         return NOTIFY_DONE;
203 }
204
205 static struct notifier_block panic_block = {
206         .notifier_call = watchdog_panic,
207 };
208
209 #ifdef CONFIG_PERF_EVENTS_NMI
210 static struct perf_event_attr wd_hw_attr = {
211         .type           = PERF_TYPE_HARDWARE,
212         .config         = PERF_COUNT_HW_CPU_CYCLES,
213         .size           = sizeof(struct perf_event_attr),
214         .pinned         = 1,
215         .disabled       = 1,
216 };
217
218 /* Callback function for perf event subsystem */
219 void watchdog_overflow_callback(struct perf_event *event, int nmi,
220                  struct perf_sample_data *data,
221                  struct pt_regs *regs)
222 {
223         int this_cpu = smp_processor_id();
224         unsigned long touch_ts = per_cpu(watchdog_touch_ts, this_cpu);
225
226         if (touch_ts == 0) {
227                 __touch_watchdog();
228                 return;
229         }
230
231         /* check for a hardlockup
232          * This is done by making sure our timer interrupt
233          * is incrementing.  The timer interrupt should have
234          * fired multiple times before we overflow'd.  If it hasn't
235          * then this is a good indication the cpu is stuck
236          */
237         if (is_hardlockup(this_cpu)) {
238                 /* only print hardlockups once */
239                 if (__get_cpu_var(hard_watchdog_warn) == true)
240                         return;
241
242                 if (hardlockup_panic)
243                         panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu);
244                 else
245                         WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu);
246
247                 __get_cpu_var(hard_watchdog_warn) = true;
248                 return;
249         }
250
251         __get_cpu_var(hard_watchdog_warn) = false;
252         return;
253 }
254 static void watchdog_interrupt_count(void)
255 {
256         __get_cpu_var(hrtimer_interrupts)++;
257 }
258 #else
259 static inline void watchdog_interrupt_count(void) { return; }
260 #endif /* CONFIG_PERF_EVENTS_NMI */
261
262 /* watchdog kicker functions */
263 static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
264 {
265         int this_cpu = smp_processor_id();
266         unsigned long touch_ts = __get_cpu_var(watchdog_touch_ts);
267         struct pt_regs *regs = get_irq_regs();
268         int duration;
269
270         /* kick the hardlockup detector */
271         watchdog_interrupt_count();
272
273         /* kick the softlockup detector */
274         wake_up_process(__get_cpu_var(softlockup_watchdog));
275
276         /* .. and repeat */
277         hrtimer_forward_now(hrtimer, ns_to_ktime(get_sample_period()));
278
279         if (touch_ts == 0) {
280                 if (unlikely(per_cpu(softlockup_touch_sync, this_cpu))) {
281                         /*
282                          * If the time stamp was touched atomically
283                          * make sure the scheduler tick is up to date.
284                          */
285                         per_cpu(softlockup_touch_sync, this_cpu) = false;
286                         sched_clock_tick();
287                 }
288                 __touch_watchdog();
289                 return HRTIMER_RESTART;
290         }
291
292         /* check for a softlockup
293          * This is done by making sure a high priority task is
294          * being scheduled.  The task touches the watchdog to
295          * indicate it is getting cpu time.  If it hasn't then
296          * this is a good indication some task is hogging the cpu
297          */
298         duration = is_softlockup(touch_ts, this_cpu);
299         if (unlikely(duration)) {
300                 /* only warn once */
301                 if (__get_cpu_var(soft_watchdog_warn) == true)
302                         return HRTIMER_RESTART;
303
304                 printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
305                         this_cpu, duration,
306                         current->comm, task_pid_nr(current));
307                 print_modules();
308                 print_irqtrace_events(current);
309                 if (regs)
310                         show_regs(regs);
311                 else
312                         dump_stack();
313
314                 if (softlockup_panic)
315                         panic("softlockup: hung tasks");
316                 __get_cpu_var(soft_watchdog_warn) = true;
317         } else
318                 __get_cpu_var(soft_watchdog_warn) = false;
319
320         return HRTIMER_RESTART;
321 }
322
323
324 /*
325  * The watchdog thread - touches the timestamp.
326  */
327 static int watchdog(void *__bind_cpu)
328 {
329         struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
330         struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, (unsigned long)__bind_cpu);
331
332         sched_setscheduler(current, SCHED_FIFO, &param);
333
334         /* initialize timestamp */
335         __touch_watchdog();
336
337         /* kick off the timer for the hardlockup detector */
338         /* done here because hrtimer_start can only pin to smp_processor_id() */
339         hrtimer_start(hrtimer, ns_to_ktime(get_sample_period()),
340                       HRTIMER_MODE_REL_PINNED);
341
342         set_current_state(TASK_INTERRUPTIBLE);
343         /*
344          * Run briefly once per second to reset the softlockup timestamp.
345          * If this gets delayed for more than 60 seconds then the
346          * debug-printout triggers in softlockup_tick().
347          */
348         while (!kthread_should_stop()) {
349                 __touch_watchdog();
350                 schedule();
351
352                 if (kthread_should_stop())
353                         break;
354
355                 set_current_state(TASK_INTERRUPTIBLE);
356         }
357         __set_current_state(TASK_RUNNING);
358
359         return 0;
360 }
361
362
363 #ifdef CONFIG_PERF_EVENTS_NMI
364 static int watchdog_nmi_enable(int cpu)
365 {
366         struct perf_event_attr *wd_attr;
367         struct perf_event *event = per_cpu(watchdog_ev, cpu);
368
369         /* is it already setup and enabled? */
370         if (event && event->state > PERF_EVENT_STATE_OFF)
371                 goto out;
372
373         /* it is setup but not enabled */
374         if (event != NULL)
375                 goto out_enable;
376
377         /* Try to register using hardware perf events */
378         wd_attr = &wd_hw_attr;
379         wd_attr->sample_period = hw_nmi_get_sample_period();
380         event = perf_event_create_kernel_counter(wd_attr, cpu, -1, watchdog_overflow_callback);
381         if (!IS_ERR(event)) {
382                 printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");
383                 goto out_save;
384         }
385
386         printk(KERN_ERR "NMI watchdog failed to create perf event on cpu%i: %p\n", cpu, event);
387         return -1;
388
389         /* success path */
390 out_save:
391         per_cpu(watchdog_ev, cpu) = event;
392 out_enable:
393         perf_event_enable(per_cpu(watchdog_ev, cpu));
394 out:
395         return 0;
396 }
397
398 static void watchdog_nmi_disable(int cpu)
399 {
400         struct perf_event *event = per_cpu(watchdog_ev, cpu);
401
402         if (event) {
403                 perf_event_disable(event);
404                 per_cpu(watchdog_ev, cpu) = NULL;
405
406                 /* should be in cleanup, but blocks oprofile */
407                 perf_event_release_kernel(event);
408         }
409         return;
410 }
411 #else
412 static int watchdog_nmi_enable(int cpu) { return 0; }
413 static void watchdog_nmi_disable(int cpu) { return; }
414 #endif /* CONFIG_PERF_EVENTS_NMI */
415
416 /* prepare/enable/disable routines */
417 static int watchdog_prepare_cpu(int cpu)
418 {
419         struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
420
421         WARN_ON(per_cpu(softlockup_watchdog, cpu));
422         hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
423         hrtimer->function = watchdog_timer_fn;
424
425         return 0;
426 }
427
428 static int watchdog_enable(int cpu)
429 {
430         struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
431
432         /* enable the perf event */
433         if (watchdog_nmi_enable(cpu) != 0)
434                 return -1;
435
436         /* create the watchdog thread */
437         if (!p) {
438                 p = kthread_create(watchdog, (void *)(unsigned long)cpu, "watchdog/%d", cpu);
439                 if (IS_ERR(p)) {
440                         printk(KERN_ERR "softlockup watchdog for %i failed\n", cpu);
441                         return -1;
442                 }
443                 kthread_bind(p, cpu);
444                 per_cpu(watchdog_touch_ts, cpu) = 0;
445                 per_cpu(softlockup_watchdog, cpu) = p;
446                 wake_up_process(p);
447         }
448
449         return 0;
450 }
451
452 static void watchdog_disable(int cpu)
453 {
454         struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
455         struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
456
457         /*
458          * cancel the timer first to stop incrementing the stats
459          * and waking up the kthread
460          */
461         hrtimer_cancel(hrtimer);
462
463         /* disable the perf event */
464         watchdog_nmi_disable(cpu);
465
466         /* stop the watchdog thread */
467         if (p) {
468                 per_cpu(softlockup_watchdog, cpu) = NULL;
469                 kthread_stop(p);
470         }
471
472         /* if any cpu succeeds, watchdog is considered enabled for the system */
473         watchdog_enabled = 1;
474 }
475
476 static void watchdog_enable_all_cpus(void)
477 {
478         int cpu;
479         int result;
480
481         for_each_online_cpu(cpu)
482                 result += watchdog_enable(cpu);
483
484         if (result)
485                 printk(KERN_ERR "watchdog: failed to be enabled on some cpus\n");
486
487 }
488
489 static void watchdog_disable_all_cpus(void)
490 {
491         int cpu;
492
493         for_each_online_cpu(cpu)
494                 watchdog_disable(cpu);
495
496         /* if all watchdogs are disabled, then they are disabled for the system */
497         watchdog_enabled = 0;
498 }
499
500
501 /* sysctl functions */
502 #ifdef CONFIG_SYSCTL
503 /*
504  * proc handler for /proc/sys/kernel/nmi_watchdog
505  */
506
507 int proc_dowatchdog_enabled(struct ctl_table *table, int write,
508                      void __user *buffer, size_t *length, loff_t *ppos)
509 {
510         proc_dointvec(table, write, buffer, length, ppos);
511
512         if (watchdog_enabled)
513                 watchdog_enable_all_cpus();
514         else
515                 watchdog_disable_all_cpus();
516         return 0;
517 }
518
519 int proc_dowatchdog_thresh(struct ctl_table *table, int write,
520                              void __user *buffer,
521                              size_t *lenp, loff_t *ppos)
522 {
523         return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
524 }
525
526 /* stub functions */
527 int proc_dosoftlockup_thresh(struct ctl_table *table, int write,
528                              void __user *buffer,
529                              size_t *lenp, loff_t *ppos)
530 {
531         return proc_dowatchdog_thresh(table, write, buffer, lenp, ppos);
532 }
533 /* end of stub functions */
534 #endif /* CONFIG_SYSCTL */
535
536
537 /*
538  * Create/destroy watchdog threads as CPUs come and go:
539  */
540 static int __cpuinit
541 cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
542 {
543         int hotcpu = (unsigned long)hcpu;
544
545         switch (action) {
546         case CPU_UP_PREPARE:
547         case CPU_UP_PREPARE_FROZEN:
548                 if (watchdog_prepare_cpu(hotcpu))
549                         return NOTIFY_BAD;
550                 break;
551         case CPU_ONLINE:
552         case CPU_ONLINE_FROZEN:
553                 if (watchdog_enable(hotcpu))
554                         return NOTIFY_BAD;
555                 break;
556 #ifdef CONFIG_HOTPLUG_CPU
557         case CPU_UP_CANCELED:
558         case CPU_UP_CANCELED_FROZEN:
559                 watchdog_disable(hotcpu);
560                 break;
561         case CPU_DEAD:
562         case CPU_DEAD_FROZEN:
563                 watchdog_disable(hotcpu);
564                 break;
565 #endif /* CONFIG_HOTPLUG_CPU */
566         }
567         return NOTIFY_OK;
568 }
569
570 static struct notifier_block __cpuinitdata cpu_nfb = {
571         .notifier_call = cpu_callback
572 };
573
574 static int __init spawn_watchdog_task(void)
575 {
576         void *cpu = (void *)(long)smp_processor_id();
577         int err;
578
579         if (no_watchdog)
580                 return 0;
581
582         err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
583         WARN_ON(err == NOTIFY_BAD);
584
585         cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
586         register_cpu_notifier(&cpu_nfb);
587
588         atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
589
590         return 0;
591 }
592 early_initcall(spawn_watchdog_task);