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