lockup_detector: Touch_softlockup cleanups and softlockup_tick removal
[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_softlockup_watchdog(void)
123 {
124         __get_cpu_var(watchdog_touch_ts) = 0;
125 }
126
127 void touch_all_softlockup_watchdogs(void)
128 {
129         int cpu;
130
131         /*
132          * this is done lockless
133          * do we care if a 0 races with a timestamp?
134          * all it means is the softlock check starts one cycle later
135          */
136         for_each_online_cpu(cpu)
137                 per_cpu(watchdog_touch_ts, cpu) = 0;
138 }
139
140 void touch_nmi_watchdog(void)
141 {
142         touch_softlockup_watchdog();
143 }
144 EXPORT_SYMBOL(touch_nmi_watchdog);
145
146 void touch_softlockup_watchdog_sync(void)
147 {
148         __raw_get_cpu_var(softlockup_touch_sync) = true;
149         __raw_get_cpu_var(watchdog_touch_ts) = 0;
150 }
151
152 #ifdef CONFIG_PERF_EVENTS_NMI
153 /* watchdog detector functions */
154 static int is_hardlockup(int cpu)
155 {
156         unsigned long hrint = per_cpu(hrtimer_interrupts, cpu);
157
158         if (per_cpu(hrtimer_interrupts_saved, cpu) == hrint)
159                 return 1;
160
161         per_cpu(hrtimer_interrupts_saved, cpu) = hrint;
162         return 0;
163 }
164 #endif
165
166 static int is_softlockup(unsigned long touch_ts, int cpu)
167 {
168         unsigned long now = get_timestamp(cpu);
169
170         /* Warn about unreasonable delays: */
171         if (time_after(now, touch_ts + softlockup_thresh))
172                 return now - touch_ts;
173
174         return 0;
175 }
176
177 static int
178 watchdog_panic(struct notifier_block *this, unsigned long event, void *ptr)
179 {
180         did_panic = 1;
181
182         return NOTIFY_DONE;
183 }
184
185 static struct notifier_block panic_block = {
186         .notifier_call = watchdog_panic,
187 };
188
189 #ifdef CONFIG_PERF_EVENTS_NMI
190 static struct perf_event_attr wd_hw_attr = {
191         .type           = PERF_TYPE_HARDWARE,
192         .config         = PERF_COUNT_HW_CPU_CYCLES,
193         .size           = sizeof(struct perf_event_attr),
194         .pinned         = 1,
195         .disabled       = 1,
196 };
197
198 /* Callback function for perf event subsystem */
199 void watchdog_overflow_callback(struct perf_event *event, int nmi,
200                  struct perf_sample_data *data,
201                  struct pt_regs *regs)
202 {
203         int this_cpu = smp_processor_id();
204         unsigned long touch_ts = per_cpu(watchdog_touch_ts, this_cpu);
205
206         if (touch_ts == 0) {
207                 __touch_watchdog();
208                 return;
209         }
210
211         /* check for a hardlockup
212          * This is done by making sure our timer interrupt
213          * is incrementing.  The timer interrupt should have
214          * fired multiple times before we overflow'd.  If it hasn't
215          * then this is a good indication the cpu is stuck
216          */
217         if (is_hardlockup(this_cpu)) {
218                 /* only print hardlockups once */
219                 if (__get_cpu_var(hard_watchdog_warn) == true)
220                         return;
221
222                 if (hardlockup_panic)
223                         panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu);
224                 else
225                         WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu);
226
227                 __get_cpu_var(hard_watchdog_warn) = true;
228                 return;
229         }
230
231         __get_cpu_var(hard_watchdog_warn) = false;
232         return;
233 }
234 static void watchdog_interrupt_count(void)
235 {
236         __get_cpu_var(hrtimer_interrupts)++;
237 }
238 #else
239 static inline void watchdog_interrupt_count(void) { return; }
240 #endif /* CONFIG_PERF_EVENTS_NMI */
241
242 /* watchdog kicker functions */
243 static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
244 {
245         int this_cpu = smp_processor_id();
246         unsigned long touch_ts = __get_cpu_var(watchdog_touch_ts);
247         struct pt_regs *regs = get_irq_regs();
248         int duration;
249
250         /* kick the hardlockup detector */
251         watchdog_interrupt_count();
252
253         /* kick the softlockup detector */
254         wake_up_process(__get_cpu_var(softlockup_watchdog));
255
256         /* .. and repeat */
257         hrtimer_forward_now(hrtimer, ns_to_ktime(get_sample_period()));
258
259         if (touch_ts == 0) {
260                 if (unlikely(per_cpu(softlockup_touch_sync, this_cpu))) {
261                         /*
262                          * If the time stamp was touched atomically
263                          * make sure the scheduler tick is up to date.
264                          */
265                         per_cpu(softlockup_touch_sync, this_cpu) = false;
266                         sched_clock_tick();
267                 }
268                 __touch_watchdog();
269                 return HRTIMER_RESTART;
270         }
271
272         /* check for a softlockup
273          * This is done by making sure a high priority task is
274          * being scheduled.  The task touches the watchdog to
275          * indicate it is getting cpu time.  If it hasn't then
276          * this is a good indication some task is hogging the cpu
277          */
278         duration = is_softlockup(touch_ts, this_cpu);
279         if (unlikely(duration)) {
280                 /* only warn once */
281                 if (__get_cpu_var(soft_watchdog_warn) == true)
282                         return HRTIMER_RESTART;
283
284                 printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
285                         this_cpu, duration,
286                         current->comm, task_pid_nr(current));
287                 print_modules();
288                 print_irqtrace_events(current);
289                 if (regs)
290                         show_regs(regs);
291                 else
292                         dump_stack();
293
294                 if (softlockup_panic)
295                         panic("softlockup: hung tasks");
296                 __get_cpu_var(soft_watchdog_warn) = true;
297         } else
298                 __get_cpu_var(soft_watchdog_warn) = false;
299
300         return HRTIMER_RESTART;
301 }
302
303
304 /*
305  * The watchdog thread - touches the timestamp.
306  */
307 static int watchdog(void *__bind_cpu)
308 {
309         struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
310         struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, (unsigned long)__bind_cpu);
311
312         sched_setscheduler(current, SCHED_FIFO, &param);
313
314         /* initialize timestamp */
315         __touch_watchdog();
316
317         /* kick off the timer for the hardlockup detector */
318         /* done here because hrtimer_start can only pin to smp_processor_id() */
319         hrtimer_start(hrtimer, ns_to_ktime(get_sample_period()),
320                       HRTIMER_MODE_REL_PINNED);
321
322         set_current_state(TASK_INTERRUPTIBLE);
323         /*
324          * Run briefly once per second to reset the softlockup timestamp.
325          * If this gets delayed for more than 60 seconds then the
326          * debug-printout triggers in softlockup_tick().
327          */
328         while (!kthread_should_stop()) {
329                 __touch_watchdog();
330                 schedule();
331
332                 if (kthread_should_stop())
333                         break;
334
335                 set_current_state(TASK_INTERRUPTIBLE);
336         }
337         __set_current_state(TASK_RUNNING);
338
339         return 0;
340 }
341
342
343 #ifdef CONFIG_PERF_EVENTS_NMI
344 static int watchdog_nmi_enable(int cpu)
345 {
346         struct perf_event_attr *wd_attr;
347         struct perf_event *event = per_cpu(watchdog_ev, cpu);
348
349         /* is it already setup and enabled? */
350         if (event && event->state > PERF_EVENT_STATE_OFF)
351                 goto out;
352
353         /* it is setup but not enabled */
354         if (event != NULL)
355                 goto out_enable;
356
357         /* Try to register using hardware perf events */
358         wd_attr = &wd_hw_attr;
359         wd_attr->sample_period = hw_nmi_get_sample_period();
360         event = perf_event_create_kernel_counter(wd_attr, cpu, -1, watchdog_overflow_callback);
361         if (!IS_ERR(event)) {
362                 printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");
363                 goto out_save;
364         }
365
366         printk(KERN_ERR "NMI watchdog failed to create perf event on cpu%i: %p\n", cpu, event);
367         return -1;
368
369         /* success path */
370 out_save:
371         per_cpu(watchdog_ev, cpu) = event;
372 out_enable:
373         perf_event_enable(per_cpu(watchdog_ev, cpu));
374 out:
375         return 0;
376 }
377
378 static void watchdog_nmi_disable(int cpu)
379 {
380         struct perf_event *event = per_cpu(watchdog_ev, cpu);
381
382         if (event) {
383                 perf_event_disable(event);
384                 per_cpu(watchdog_ev, cpu) = NULL;
385
386                 /* should be in cleanup, but blocks oprofile */
387                 perf_event_release_kernel(event);
388         }
389         return;
390 }
391 #else
392 static int watchdog_nmi_enable(int cpu) { return 0; }
393 static void watchdog_nmi_disable(int cpu) { return; }
394 #endif /* CONFIG_PERF_EVENTS_NMI */
395
396 /* prepare/enable/disable routines */
397 static int watchdog_prepare_cpu(int cpu)
398 {
399         struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
400
401         WARN_ON(per_cpu(softlockup_watchdog, cpu));
402         hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
403         hrtimer->function = watchdog_timer_fn;
404
405         return 0;
406 }
407
408 static int watchdog_enable(int cpu)
409 {
410         struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
411
412         /* enable the perf event */
413         if (watchdog_nmi_enable(cpu) != 0)
414                 return -1;
415
416         /* create the watchdog thread */
417         if (!p) {
418                 p = kthread_create(watchdog, (void *)(unsigned long)cpu, "watchdog/%d", cpu);
419                 if (IS_ERR(p)) {
420                         printk(KERN_ERR "softlockup watchdog for %i failed\n", cpu);
421                         return -1;
422                 }
423                 kthread_bind(p, cpu);
424                 per_cpu(watchdog_touch_ts, cpu) = 0;
425                 per_cpu(softlockup_watchdog, cpu) = p;
426                 wake_up_process(p);
427         }
428
429         return 0;
430 }
431
432 static void watchdog_disable(int cpu)
433 {
434         struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
435         struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
436
437         /*
438          * cancel the timer first to stop incrementing the stats
439          * and waking up the kthread
440          */
441         hrtimer_cancel(hrtimer);
442
443         /* disable the perf event */
444         watchdog_nmi_disable(cpu);
445
446         /* stop the watchdog thread */
447         if (p) {
448                 per_cpu(softlockup_watchdog, cpu) = NULL;
449                 kthread_stop(p);
450         }
451
452         /* if any cpu succeeds, watchdog is considered enabled for the system */
453         watchdog_enabled = 1;
454 }
455
456 static void watchdog_enable_all_cpus(void)
457 {
458         int cpu;
459         int result;
460
461         for_each_online_cpu(cpu)
462                 result += watchdog_enable(cpu);
463
464         if (result)
465                 printk(KERN_ERR "watchdog: failed to be enabled on some cpus\n");
466
467 }
468
469 static void watchdog_disable_all_cpus(void)
470 {
471         int cpu;
472
473         for_each_online_cpu(cpu)
474                 watchdog_disable(cpu);
475
476         /* if all watchdogs are disabled, then they are disabled for the system */
477         watchdog_enabled = 0;
478 }
479
480
481 /* sysctl functions */
482 #ifdef CONFIG_SYSCTL
483 /*
484  * proc handler for /proc/sys/kernel/nmi_watchdog
485  */
486
487 int proc_dowatchdog_enabled(struct ctl_table *table, int write,
488                      void __user *buffer, size_t *length, loff_t *ppos)
489 {
490         proc_dointvec(table, write, buffer, length, ppos);
491
492         if (watchdog_enabled)
493                 watchdog_enable_all_cpus();
494         else
495                 watchdog_disable_all_cpus();
496         return 0;
497 }
498
499 int proc_dowatchdog_thresh(struct ctl_table *table, int write,
500                              void __user *buffer,
501                              size_t *lenp, loff_t *ppos)
502 {
503         return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
504 }
505 #endif /* CONFIG_SYSCTL */
506
507
508 /*
509  * Create/destroy watchdog threads as CPUs come and go:
510  */
511 static int __cpuinit
512 cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
513 {
514         int hotcpu = (unsigned long)hcpu;
515
516         switch (action) {
517         case CPU_UP_PREPARE:
518         case CPU_UP_PREPARE_FROZEN:
519                 if (watchdog_prepare_cpu(hotcpu))
520                         return NOTIFY_BAD;
521                 break;
522         case CPU_ONLINE:
523         case CPU_ONLINE_FROZEN:
524                 if (watchdog_enable(hotcpu))
525                         return NOTIFY_BAD;
526                 break;
527 #ifdef CONFIG_HOTPLUG_CPU
528         case CPU_UP_CANCELED:
529         case CPU_UP_CANCELED_FROZEN:
530                 watchdog_disable(hotcpu);
531                 break;
532         case CPU_DEAD:
533         case CPU_DEAD_FROZEN:
534                 watchdog_disable(hotcpu);
535                 break;
536 #endif /* CONFIG_HOTPLUG_CPU */
537         }
538         return NOTIFY_OK;
539 }
540
541 static struct notifier_block __cpuinitdata cpu_nfb = {
542         .notifier_call = cpu_callback
543 };
544
545 static int __init spawn_watchdog_task(void)
546 {
547         void *cpu = (void *)(long)smp_processor_id();
548         int err;
549
550         if (no_watchdog)
551                 return 0;
552
553         err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
554         WARN_ON(err == NOTIFY_BAD);
555
556         cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
557         register_cpu_notifier(&cpu_nfb);
558
559         atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
560
561         return 0;
562 }
563 early_initcall(spawn_watchdog_task);