Root/
1 | /* |
2 | * Detect hard and soft lockups on a system |
3 | * |
4 | * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc. |
5 | * |
6 | * Note: Most of this code is borrowed heavily from the original softlockup |
7 | * detector, so thanks to Ingo for the initial implementation. |
8 | * Some chunks also taken from the old x86-specific nmi watchdog code, thanks |
9 | * to those contributors as well. |
10 | */ |
11 | |
12 | #define pr_fmt(fmt) "NMI watchdog: " fmt |
13 | |
14 | #include <linux/mm.h> |
15 | #include <linux/cpu.h> |
16 | #include <linux/nmi.h> |
17 | #include <linux/init.h> |
18 | #include <linux/delay.h> |
19 | #include <linux/freezer.h> |
20 | #include <linux/kthread.h> |
21 | #include <linux/lockdep.h> |
22 | #include <linux/notifier.h> |
23 | #include <linux/module.h> |
24 | #include <linux/sysctl.h> |
25 | #include <linux/smpboot.h> |
26 | #include <linux/sched/rt.h> |
27 | |
28 | #include <asm/irq_regs.h> |
29 | #include <linux/kvm_para.h> |
30 | #include <linux/perf_event.h> |
31 | |
32 | int watchdog_user_enabled = 1; |
33 | int __read_mostly watchdog_thresh = 10; |
34 | #ifdef CONFIG_SMP |
35 | int __read_mostly sysctl_softlockup_all_cpu_backtrace; |
36 | #else |
37 | #define sysctl_softlockup_all_cpu_backtrace 0 |
38 | #endif |
39 | |
40 | static int __read_mostly watchdog_running; |
41 | static u64 __read_mostly sample_period; |
42 | |
43 | static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); |
44 | static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog); |
45 | static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer); |
46 | static DEFINE_PER_CPU(bool, softlockup_touch_sync); |
47 | static DEFINE_PER_CPU(bool, soft_watchdog_warn); |
48 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); |
49 | static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt); |
50 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
51 | static DEFINE_PER_CPU(bool, hard_watchdog_warn); |
52 | static DEFINE_PER_CPU(bool, watchdog_nmi_touch); |
53 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); |
54 | static DEFINE_PER_CPU(struct perf_event *, watchdog_ev); |
55 | #endif |
56 | static unsigned long soft_lockup_nmi_warn; |
57 | |
58 | /* boot commands */ |
59 | /* |
60 | * Should we panic when a soft-lockup or hard-lockup occurs: |
61 | */ |
62 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
63 | static int hardlockup_panic = |
64 | CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE; |
65 | |
66 | static int __init hardlockup_panic_setup(char *str) |
67 | { |
68 | if (!strncmp(str, "panic", 5)) |
69 | hardlockup_panic = 1; |
70 | else if (!strncmp(str, "nopanic", 7)) |
71 | hardlockup_panic = 0; |
72 | else if (!strncmp(str, "0", 1)) |
73 | watchdog_user_enabled = 0; |
74 | return 1; |
75 | } |
76 | __setup("nmi_watchdog=", hardlockup_panic_setup); |
77 | #endif |
78 | |
79 | unsigned int __read_mostly softlockup_panic = |
80 | CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE; |
81 | |
82 | static int __init softlockup_panic_setup(char *str) |
83 | { |
84 | softlockup_panic = simple_strtoul(str, NULL, 0); |
85 | |
86 | return 1; |
87 | } |
88 | __setup("softlockup_panic=", softlockup_panic_setup); |
89 | |
90 | static int __init nowatchdog_setup(char *str) |
91 | { |
92 | watchdog_user_enabled = 0; |
93 | return 1; |
94 | } |
95 | __setup("nowatchdog", nowatchdog_setup); |
96 | |
97 | /* deprecated */ |
98 | static int __init nosoftlockup_setup(char *str) |
99 | { |
100 | watchdog_user_enabled = 0; |
101 | return 1; |
102 | } |
103 | __setup("nosoftlockup", nosoftlockup_setup); |
104 | /* */ |
105 | #ifdef CONFIG_SMP |
106 | static int __init softlockup_all_cpu_backtrace_setup(char *str) |
107 | { |
108 | sysctl_softlockup_all_cpu_backtrace = |
109 | !!simple_strtol(str, NULL, 0); |
110 | return 1; |
111 | } |
112 | __setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup); |
113 | #endif |
114 | |
115 | /* |
116 | * Hard-lockup warnings should be triggered after just a few seconds. Soft- |
117 | * lockups can have false positives under extreme conditions. So we generally |
118 | * want a higher threshold for soft lockups than for hard lockups. So we couple |
119 | * the thresholds with a factor: we make the soft threshold twice the amount of |
120 | * time the hard threshold is. |
121 | */ |
122 | static int get_softlockup_thresh(void) |
123 | { |
124 | return watchdog_thresh * 2; |
125 | } |
126 | |
127 | /* |
128 | * Returns seconds, approximately. We don't need nanosecond |
129 | * resolution, and we don't need to waste time with a big divide when |
130 | * 2^30ns == 1.074s. |
131 | */ |
132 | static unsigned long get_timestamp(void) |
133 | { |
134 | return local_clock() >> 30LL; /* 2^30 ~= 10^9 */ |
135 | } |
136 | |
137 | static void set_sample_period(void) |
138 | { |
139 | /* |
140 | * convert watchdog_thresh from seconds to ns |
141 | * the divide by 5 is to give hrtimer several chances (two |
142 | * or three with the current relation between the soft |
143 | * and hard thresholds) to increment before the |
144 | * hardlockup detector generates a warning |
145 | */ |
146 | sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); |
147 | } |
148 | |
149 | /* Commands for resetting the watchdog */ |
150 | static void __touch_watchdog(void) |
151 | { |
152 | __this_cpu_write(watchdog_touch_ts, get_timestamp()); |
153 | } |
154 | |
155 | void touch_softlockup_watchdog(void) |
156 | { |
157 | /* |
158 | * Preemption can be enabled. It doesn't matter which CPU's timestamp |
159 | * gets zeroed here, so use the raw_ operation. |
160 | */ |
161 | raw_cpu_write(watchdog_touch_ts, 0); |
162 | } |
163 | EXPORT_SYMBOL(touch_softlockup_watchdog); |
164 | |
165 | void touch_all_softlockup_watchdogs(void) |
166 | { |
167 | int cpu; |
168 | |
169 | /* |
170 | * this is done lockless |
171 | * do we care if a 0 races with a timestamp? |
172 | * all it means is the softlock check starts one cycle later |
173 | */ |
174 | for_each_online_cpu(cpu) |
175 | per_cpu(watchdog_touch_ts, cpu) = 0; |
176 | } |
177 | |
178 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
179 | void touch_nmi_watchdog(void) |
180 | { |
181 | /* |
182 | * Using __raw here because some code paths have |
183 | * preemption enabled. If preemption is enabled |
184 | * then interrupts should be enabled too, in which |
185 | * case we shouldn't have to worry about the watchdog |
186 | * going off. |
187 | */ |
188 | __raw_get_cpu_var(watchdog_nmi_touch) = true; |
189 | touch_softlockup_watchdog(); |
190 | } |
191 | EXPORT_SYMBOL(touch_nmi_watchdog); |
192 | |
193 | #endif |
194 | |
195 | void touch_softlockup_watchdog_sync(void) |
196 | { |
197 | __raw_get_cpu_var(softlockup_touch_sync) = true; |
198 | __raw_get_cpu_var(watchdog_touch_ts) = 0; |
199 | } |
200 | |
201 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
202 | /* watchdog detector functions */ |
203 | static int is_hardlockup(void) |
204 | { |
205 | unsigned long hrint = __this_cpu_read(hrtimer_interrupts); |
206 | |
207 | if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) |
208 | return 1; |
209 | |
210 | __this_cpu_write(hrtimer_interrupts_saved, hrint); |
211 | return 0; |
212 | } |
213 | #endif |
214 | |
215 | static int is_softlockup(unsigned long touch_ts) |
216 | { |
217 | unsigned long now = get_timestamp(); |
218 | |
219 | /* Warn about unreasonable delays: */ |
220 | if (time_after(now, touch_ts + get_softlockup_thresh())) |
221 | return now - touch_ts; |
222 | |
223 | return 0; |
224 | } |
225 | |
226 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
227 | |
228 | static struct perf_event_attr wd_hw_attr = { |
229 | .type = PERF_TYPE_HARDWARE, |
230 | .config = PERF_COUNT_HW_CPU_CYCLES, |
231 | .size = sizeof(struct perf_event_attr), |
232 | .pinned = 1, |
233 | .disabled = 1, |
234 | }; |
235 | |
236 | /* Callback function for perf event subsystem */ |
237 | static void watchdog_overflow_callback(struct perf_event *event, |
238 | struct perf_sample_data *data, |
239 | struct pt_regs *regs) |
240 | { |
241 | /* Ensure the watchdog never gets throttled */ |
242 | event->hw.interrupts = 0; |
243 | |
244 | if (__this_cpu_read(watchdog_nmi_touch) == true) { |
245 | __this_cpu_write(watchdog_nmi_touch, false); |
246 | return; |
247 | } |
248 | |
249 | /* check for a hardlockup |
250 | * This is done by making sure our timer interrupt |
251 | * is incrementing. The timer interrupt should have |
252 | * fired multiple times before we overflow'd. If it hasn't |
253 | * then this is a good indication the cpu is stuck |
254 | */ |
255 | if (is_hardlockup()) { |
256 | int this_cpu = smp_processor_id(); |
257 | |
258 | /* only print hardlockups once */ |
259 | if (__this_cpu_read(hard_watchdog_warn) == true) |
260 | return; |
261 | |
262 | if (hardlockup_panic) |
263 | panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu); |
264 | else |
265 | WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu); |
266 | |
267 | __this_cpu_write(hard_watchdog_warn, true); |
268 | return; |
269 | } |
270 | |
271 | __this_cpu_write(hard_watchdog_warn, false); |
272 | return; |
273 | } |
274 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
275 | |
276 | static void watchdog_interrupt_count(void) |
277 | { |
278 | __this_cpu_inc(hrtimer_interrupts); |
279 | } |
280 | |
281 | static int watchdog_nmi_enable(unsigned int cpu); |
282 | static void watchdog_nmi_disable(unsigned int cpu); |
283 | |
284 | /* watchdog kicker functions */ |
285 | static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) |
286 | { |
287 | unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts); |
288 | struct pt_regs *regs = get_irq_regs(); |
289 | int duration; |
290 | int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; |
291 | |
292 | /* kick the hardlockup detector */ |
293 | watchdog_interrupt_count(); |
294 | |
295 | /* kick the softlockup detector */ |
296 | wake_up_process(__this_cpu_read(softlockup_watchdog)); |
297 | |
298 | /* .. and repeat */ |
299 | hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period)); |
300 | |
301 | if (touch_ts == 0) { |
302 | if (unlikely(__this_cpu_read(softlockup_touch_sync))) { |
303 | /* |
304 | * If the time stamp was touched atomically |
305 | * make sure the scheduler tick is up to date. |
306 | */ |
307 | __this_cpu_write(softlockup_touch_sync, false); |
308 | sched_clock_tick(); |
309 | } |
310 | |
311 | /* Clear the guest paused flag on watchdog reset */ |
312 | kvm_check_and_clear_guest_paused(); |
313 | __touch_watchdog(); |
314 | return HRTIMER_RESTART; |
315 | } |
316 | |
317 | /* check for a softlockup |
318 | * This is done by making sure a high priority task is |
319 | * being scheduled. The task touches the watchdog to |
320 | * indicate it is getting cpu time. If it hasn't then |
321 | * this is a good indication some task is hogging the cpu |
322 | */ |
323 | duration = is_softlockup(touch_ts); |
324 | if (unlikely(duration)) { |
325 | /* |
326 | * If a virtual machine is stopped by the host it can look to |
327 | * the watchdog like a soft lockup, check to see if the host |
328 | * stopped the vm before we issue the warning |
329 | */ |
330 | if (kvm_check_and_clear_guest_paused()) |
331 | return HRTIMER_RESTART; |
332 | |
333 | /* only warn once */ |
334 | if (__this_cpu_read(soft_watchdog_warn) == true) |
335 | return HRTIMER_RESTART; |
336 | |
337 | if (softlockup_all_cpu_backtrace) { |
338 | /* Prevent multiple soft-lockup reports if one cpu is already |
339 | * engaged in dumping cpu back traces |
340 | */ |
341 | if (test_and_set_bit(0, &soft_lockup_nmi_warn)) { |
342 | /* Someone else will report us. Let's give up */ |
343 | __this_cpu_write(soft_watchdog_warn, true); |
344 | return HRTIMER_RESTART; |
345 | } |
346 | } |
347 | |
348 | printk(KERN_EMERG "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", |
349 | smp_processor_id(), duration, |
350 | current->comm, task_pid_nr(current)); |
351 | print_modules(); |
352 | print_irqtrace_events(current); |
353 | if (regs) |
354 | show_regs(regs); |
355 | else |
356 | dump_stack(); |
357 | |
358 | if (softlockup_all_cpu_backtrace) { |
359 | /* Avoid generating two back traces for current |
360 | * given that one is already made above |
361 | */ |
362 | trigger_allbutself_cpu_backtrace(); |
363 | |
364 | clear_bit(0, &soft_lockup_nmi_warn); |
365 | /* Barrier to sync with other cpus */ |
366 | smp_mb__after_atomic(); |
367 | } |
368 | |
369 | if (softlockup_panic) |
370 | panic("softlockup: hung tasks"); |
371 | __this_cpu_write(soft_watchdog_warn, true); |
372 | } else |
373 | __this_cpu_write(soft_watchdog_warn, false); |
374 | |
375 | return HRTIMER_RESTART; |
376 | } |
377 | |
378 | static void watchdog_set_prio(unsigned int policy, unsigned int prio) |
379 | { |
380 | struct sched_param param = { .sched_priority = prio }; |
381 | |
382 | sched_setscheduler(current, policy, ¶m); |
383 | } |
384 | |
385 | static void watchdog_enable(unsigned int cpu) |
386 | { |
387 | struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); |
388 | |
389 | /* kick off the timer for the hardlockup detector */ |
390 | hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
391 | hrtimer->function = watchdog_timer_fn; |
392 | |
393 | /* Enable the perf event */ |
394 | watchdog_nmi_enable(cpu); |
395 | |
396 | /* done here because hrtimer_start can only pin to smp_processor_id() */ |
397 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
398 | HRTIMER_MODE_REL_PINNED); |
399 | |
400 | /* initialize timestamp */ |
401 | watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1); |
402 | __touch_watchdog(); |
403 | } |
404 | |
405 | static void watchdog_disable(unsigned int cpu) |
406 | { |
407 | struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); |
408 | |
409 | watchdog_set_prio(SCHED_NORMAL, 0); |
410 | hrtimer_cancel(hrtimer); |
411 | /* disable the perf event */ |
412 | watchdog_nmi_disable(cpu); |
413 | } |
414 | |
415 | static void watchdog_cleanup(unsigned int cpu, bool online) |
416 | { |
417 | watchdog_disable(cpu); |
418 | } |
419 | |
420 | static int watchdog_should_run(unsigned int cpu) |
421 | { |
422 | return __this_cpu_read(hrtimer_interrupts) != |
423 | __this_cpu_read(soft_lockup_hrtimer_cnt); |
424 | } |
425 | |
426 | /* |
427 | * The watchdog thread function - touches the timestamp. |
428 | * |
429 | * It only runs once every sample_period seconds (4 seconds by |
430 | * default) to reset the softlockup timestamp. If this gets delayed |
431 | * for more than 2*watchdog_thresh seconds then the debug-printout |
432 | * triggers in watchdog_timer_fn(). |
433 | */ |
434 | static void watchdog(unsigned int cpu) |
435 | { |
436 | __this_cpu_write(soft_lockup_hrtimer_cnt, |
437 | __this_cpu_read(hrtimer_interrupts)); |
438 | __touch_watchdog(); |
439 | } |
440 | |
441 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
442 | /* |
443 | * People like the simple clean cpu node info on boot. |
444 | * Reduce the watchdog noise by only printing messages |
445 | * that are different from what cpu0 displayed. |
446 | */ |
447 | static unsigned long cpu0_err; |
448 | |
449 | static int watchdog_nmi_enable(unsigned int cpu) |
450 | { |
451 | struct perf_event_attr *wd_attr; |
452 | struct perf_event *event = per_cpu(watchdog_ev, cpu); |
453 | |
454 | /* is it already setup and enabled? */ |
455 | if (event && event->state > PERF_EVENT_STATE_OFF) |
456 | goto out; |
457 | |
458 | /* it is setup but not enabled */ |
459 | if (event != NULL) |
460 | goto out_enable; |
461 | |
462 | wd_attr = &wd_hw_attr; |
463 | wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); |
464 | |
465 | /* Try to register using hardware perf events */ |
466 | event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL); |
467 | |
468 | /* save cpu0 error for future comparision */ |
469 | if (cpu == 0 && IS_ERR(event)) |
470 | cpu0_err = PTR_ERR(event); |
471 | |
472 | if (!IS_ERR(event)) { |
473 | /* only print for cpu0 or different than cpu0 */ |
474 | if (cpu == 0 || cpu0_err) |
475 | pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n"); |
476 | goto out_save; |
477 | } |
478 | |
479 | /* skip displaying the same error again */ |
480 | if (cpu > 0 && (PTR_ERR(event) == cpu0_err)) |
481 | return PTR_ERR(event); |
482 | |
483 | /* vary the KERN level based on the returned errno */ |
484 | if (PTR_ERR(event) == -EOPNOTSUPP) |
485 | pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu); |
486 | else if (PTR_ERR(event) == -ENOENT) |
487 | pr_warning("disabled (cpu%i): hardware events not enabled\n", |
488 | cpu); |
489 | else |
490 | pr_err("disabled (cpu%i): unable to create perf event: %ld\n", |
491 | cpu, PTR_ERR(event)); |
492 | return PTR_ERR(event); |
493 | |
494 | /* success path */ |
495 | out_save: |
496 | per_cpu(watchdog_ev, cpu) = event; |
497 | out_enable: |
498 | perf_event_enable(per_cpu(watchdog_ev, cpu)); |
499 | out: |
500 | return 0; |
501 | } |
502 | |
503 | static void watchdog_nmi_disable(unsigned int cpu) |
504 | { |
505 | struct perf_event *event = per_cpu(watchdog_ev, cpu); |
506 | |
507 | if (event) { |
508 | perf_event_disable(event); |
509 | per_cpu(watchdog_ev, cpu) = NULL; |
510 | |
511 | /* should be in cleanup, but blocks oprofile */ |
512 | perf_event_release_kernel(event); |
513 | } |
514 | return; |
515 | } |
516 | #else |
517 | static int watchdog_nmi_enable(unsigned int cpu) { return 0; } |
518 | static void watchdog_nmi_disable(unsigned int cpu) { return; } |
519 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
520 | |
521 | static struct smp_hotplug_thread watchdog_threads = { |
522 | .store = &softlockup_watchdog, |
523 | .thread_should_run = watchdog_should_run, |
524 | .thread_fn = watchdog, |
525 | .thread_comm = "watchdog/%u", |
526 | .setup = watchdog_enable, |
527 | .cleanup = watchdog_cleanup, |
528 | .park = watchdog_disable, |
529 | .unpark = watchdog_enable, |
530 | }; |
531 | |
532 | static void restart_watchdog_hrtimer(void *info) |
533 | { |
534 | struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); |
535 | int ret; |
536 | |
537 | /* |
538 | * No need to cancel and restart hrtimer if it is currently executing |
539 | * because it will reprogram itself with the new period now. |
540 | * We should never see it unqueued here because we are running per-cpu |
541 | * with interrupts disabled. |
542 | */ |
543 | ret = hrtimer_try_to_cancel(hrtimer); |
544 | if (ret == 1) |
545 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
546 | HRTIMER_MODE_REL_PINNED); |
547 | } |
548 | |
549 | static void update_timers(int cpu) |
550 | { |
551 | /* |
552 | * Make sure that perf event counter will adopt to a new |
553 | * sampling period. Updating the sampling period directly would |
554 | * be much nicer but we do not have an API for that now so |
555 | * let's use a big hammer. |
556 | * Hrtimer will adopt the new period on the next tick but this |
557 | * might be late already so we have to restart the timer as well. |
558 | */ |
559 | watchdog_nmi_disable(cpu); |
560 | smp_call_function_single(cpu, restart_watchdog_hrtimer, NULL, 1); |
561 | watchdog_nmi_enable(cpu); |
562 | } |
563 | |
564 | static void update_timers_all_cpus(void) |
565 | { |
566 | int cpu; |
567 | |
568 | get_online_cpus(); |
569 | for_each_online_cpu(cpu) |
570 | update_timers(cpu); |
571 | put_online_cpus(); |
572 | } |
573 | |
574 | static int watchdog_enable_all_cpus(bool sample_period_changed) |
575 | { |
576 | int err = 0; |
577 | |
578 | if (!watchdog_running) { |
579 | err = smpboot_register_percpu_thread(&watchdog_threads); |
580 | if (err) |
581 | pr_err("Failed to create watchdog threads, disabled\n"); |
582 | else |
583 | watchdog_running = 1; |
584 | } else if (sample_period_changed) { |
585 | update_timers_all_cpus(); |
586 | } |
587 | |
588 | return err; |
589 | } |
590 | |
591 | /* prepare/enable/disable routines */ |
592 | /* sysctl functions */ |
593 | #ifdef CONFIG_SYSCTL |
594 | static void watchdog_disable_all_cpus(void) |
595 | { |
596 | if (watchdog_running) { |
597 | watchdog_running = 0; |
598 | smpboot_unregister_percpu_thread(&watchdog_threads); |
599 | } |
600 | } |
601 | |
602 | /* |
603 | * proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh |
604 | */ |
605 | |
606 | int proc_dowatchdog(struct ctl_table *table, int write, |
607 | void __user *buffer, size_t *lenp, loff_t *ppos) |
608 | { |
609 | int err, old_thresh, old_enabled; |
610 | static DEFINE_MUTEX(watchdog_proc_mutex); |
611 | |
612 | mutex_lock(&watchdog_proc_mutex); |
613 | old_thresh = ACCESS_ONCE(watchdog_thresh); |
614 | old_enabled = ACCESS_ONCE(watchdog_user_enabled); |
615 | |
616 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
617 | if (err || !write) |
618 | goto out; |
619 | |
620 | set_sample_period(); |
621 | /* |
622 | * Watchdog threads shouldn't be enabled if they are |
623 | * disabled. The 'watchdog_running' variable check in |
624 | * watchdog_*_all_cpus() function takes care of this. |
625 | */ |
626 | if (watchdog_user_enabled && watchdog_thresh) |
627 | err = watchdog_enable_all_cpus(old_thresh != watchdog_thresh); |
628 | else |
629 | watchdog_disable_all_cpus(); |
630 | |
631 | /* Restore old values on failure */ |
632 | if (err) { |
633 | watchdog_thresh = old_thresh; |
634 | watchdog_user_enabled = old_enabled; |
635 | } |
636 | out: |
637 | mutex_unlock(&watchdog_proc_mutex); |
638 | return err; |
639 | } |
640 | #endif /* CONFIG_SYSCTL */ |
641 | |
642 | void __init lockup_detector_init(void) |
643 | { |
644 | set_sample_period(); |
645 | |
646 | if (watchdog_user_enabled) |
647 | watchdog_enable_all_cpus(false); |
648 | } |
649 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9