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