lockup_detector: Sync touch_*_watchdog back to old semantics
[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 __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_HARDLOCKUP_DETECTOR
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 = 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         __raw_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 #ifdef CONFIG_HARDLOCKUP_DETECTOR
143 void touch_nmi_watchdog(void)
144 {
145         if (watchdog_enabled) {
146                 unsigned cpu;
147
148                 for_each_present_cpu(cpu) {
149                         if (per_cpu(watchdog_nmi_touch, cpu) != true)
150                                 per_cpu(watchdog_nmi_touch, cpu) = true;
151                 }
152         }
153         touch_softlockup_watchdog();
154 }
155 EXPORT_SYMBOL(touch_nmi_watchdog);
156
157 #endif
158
159 void touch_softlockup_watchdog_sync(void)
160 {
161         __raw_get_cpu_var(softlockup_touch_sync) = true;
162         __raw_get_cpu_var(watchdog_touch_ts) = 0;
163 }
164
165 #ifdef CONFIG_HARDLOCKUP_DETECTOR
166 /* watchdog detector functions */
167 static int is_hardlockup(void)
168 {
169         unsigned long hrint = __get_cpu_var(hrtimer_interrupts);
170
171         if (__get_cpu_var(hrtimer_interrupts_saved) == hrint)
172                 return 1;
173
174         __get_cpu_var(hrtimer_interrupts_saved) = hrint;
175         return 0;
176 }
177 #endif
178
179 static int is_softlockup(unsigned long touch_ts)
180 {
181         unsigned long now = get_timestamp(smp_processor_id());
182
183         /* Warn about unreasonable delays: */
184         if (time_after(now, touch_ts + softlockup_thresh))
185                 return now - touch_ts;
186
187         return 0;
188 }
189
190 static int
191 watchdog_panic(struct notifier_block *this, unsigned long event, void *ptr)
192 {
193         did_panic = 1;
194
195         return NOTIFY_DONE;
196 }
197
198 static struct notifier_block panic_block = {
199         .notifier_call = watchdog_panic,
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 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 (__get_cpu_var(watchdog_nmi_touch) == true) {
220                 __get_cpu_var(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 (__get_cpu_var(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                 __get_cpu_var(hard_watchdog_warn) = true;
243                 return;
244         }
245
246         __get_cpu_var(hard_watchdog_warn) = false;
247         return;
248 }
249 static void watchdog_interrupt_count(void)
250 {
251         __get_cpu_var(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 = __get_cpu_var(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(__get_cpu_var(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(__get_cpu_var(softlockup_touch_sync))) {
275                         /*
276                          * If the time stamp was touched atomically
277                          * make sure the scheduler tick is up to date.
278                          */
279                         __get_cpu_var(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 (__get_cpu_var(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                 __get_cpu_var(soft_watchdog_warn) = true;
311         } else
312                 __get_cpu_var(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         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();
374         event = perf_event_create_kernel_counter(wd_attr, cpu, -1, 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         printk(KERN_ERR "NMI watchdog failed to create perf event on cpu%i: %p\n", cpu, event);
381         return -1;
382
383         /* success path */
384 out_save:
385         per_cpu(watchdog_ev, cpu) = event;
386 out_enable:
387         perf_event_enable(per_cpu(watchdog_ev, cpu));
388 out:
389         return 0;
390 }
391
392 static void watchdog_nmi_disable(int cpu)
393 {
394         struct perf_event *event = per_cpu(watchdog_ev, cpu);
395
396         if (event) {
397                 perf_event_disable(event);
398                 per_cpu(watchdog_ev, cpu) = NULL;
399
400                 /* should be in cleanup, but blocks oprofile */
401                 perf_event_release_kernel(event);
402         }
403         return;
404 }
405 #else
406 static int watchdog_nmi_enable(int cpu) { return 0; }
407 static void watchdog_nmi_disable(int cpu) { return; }
408 #endif /* CONFIG_HARDLOCKUP_DETECTOR */
409
410 /* prepare/enable/disable routines */
411 static int watchdog_prepare_cpu(int cpu)
412 {
413         struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
414
415         WARN_ON(per_cpu(softlockup_watchdog, cpu));
416         hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
417         hrtimer->function = watchdog_timer_fn;
418
419         return 0;
420 }
421
422 static int watchdog_enable(int cpu)
423 {
424         struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
425
426         /* enable the perf event */
427         if (watchdog_nmi_enable(cpu) != 0)
428                 return -1;
429
430         /* create the watchdog thread */
431         if (!p) {
432                 p = kthread_create(watchdog, (void *)(unsigned long)cpu, "watchdog/%d", cpu);
433                 if (IS_ERR(p)) {
434                         printk(KERN_ERR "softlockup watchdog for %i failed\n", cpu);
435                         return -1;
436                 }
437                 kthread_bind(p, cpu);
438                 per_cpu(watchdog_touch_ts, cpu) = 0;
439                 per_cpu(softlockup_watchdog, cpu) = p;
440                 wake_up_process(p);
441         }
442
443         /* if any cpu succeeds, watchdog is considered enabled for the system */
444         watchdog_enabled = 1;
445
446         return 0;
447 }
448
449 static void watchdog_disable(int cpu)
450 {
451         struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
452         struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
453
454         /*
455          * cancel the timer first to stop incrementing the stats
456          * and waking up the kthread
457          */
458         hrtimer_cancel(hrtimer);
459
460         /* disable the perf event */
461         watchdog_nmi_disable(cpu);
462
463         /* stop the watchdog thread */
464         if (p) {
465                 per_cpu(softlockup_watchdog, cpu) = NULL;
466                 kthread_stop(p);
467         }
468 }
469
470 static void watchdog_enable_all_cpus(void)
471 {
472         int cpu;
473         int result = 0;
474
475         for_each_online_cpu(cpu)
476                 result += watchdog_enable(cpu);
477
478         if (result)
479                 printk(KERN_ERR "watchdog: failed to be enabled on some cpus\n");
480
481 }
482
483 static void watchdog_disable_all_cpus(void)
484 {
485         int cpu;
486
487         for_each_online_cpu(cpu)
488                 watchdog_disable(cpu);
489
490         /* if all watchdogs are disabled, then they are disabled for the system */
491         watchdog_enabled = 0;
492 }
493
494
495 /* sysctl functions */
496 #ifdef CONFIG_SYSCTL
497 /*
498  * proc handler for /proc/sys/kernel/nmi_watchdog
499  */
500
501 int proc_dowatchdog_enabled(struct ctl_table *table, int write,
502                      void __user *buffer, size_t *length, loff_t *ppos)
503 {
504         proc_dointvec(table, write, buffer, length, ppos);
505
506         if (watchdog_enabled)
507                 watchdog_enable_all_cpus();
508         else
509                 watchdog_disable_all_cpus();
510         return 0;
511 }
512
513 int proc_dowatchdog_thresh(struct ctl_table *table, int write,
514                              void __user *buffer,
515                              size_t *lenp, loff_t *ppos)
516 {
517         return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
518 }
519 #endif /* CONFIG_SYSCTL */
520
521
522 /*
523  * Create/destroy watchdog threads as CPUs come and go:
524  */
525 static int __cpuinit
526 cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
527 {
528         int hotcpu = (unsigned long)hcpu;
529
530         switch (action) {
531         case CPU_UP_PREPARE:
532         case CPU_UP_PREPARE_FROZEN:
533                 if (watchdog_prepare_cpu(hotcpu))
534                         return NOTIFY_BAD;
535                 break;
536         case CPU_ONLINE:
537         case CPU_ONLINE_FROZEN:
538                 if (watchdog_enable(hotcpu))
539                         return NOTIFY_BAD;
540                 break;
541 #ifdef CONFIG_HOTPLUG_CPU
542         case CPU_UP_CANCELED:
543         case CPU_UP_CANCELED_FROZEN:
544                 watchdog_disable(hotcpu);
545                 break;
546         case CPU_DEAD:
547         case CPU_DEAD_FROZEN:
548                 watchdog_disable(hotcpu);
549                 break;
550 #endif /* CONFIG_HOTPLUG_CPU */
551         }
552         return NOTIFY_OK;
553 }
554
555 static struct notifier_block __cpuinitdata cpu_nfb = {
556         .notifier_call = cpu_callback
557 };
558
559 static int __init spawn_watchdog_task(void)
560 {
561         void *cpu = (void *)(long)smp_processor_id();
562         int err;
563
564         if (no_watchdog)
565                 return 0;
566
567         err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
568         WARN_ON(err == NOTIFY_BAD);
569
570         cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
571         register_cpu_notifier(&cpu_nfb);
572
573         atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
574
575         return 0;
576 }
577 early_initcall(spawn_watchdog_task);