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