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Commit | Line | Data |
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58687acb DZ |
1 | /* |
2 | * Detect hard and soft lockups on a system | |
3 | * | |
4 | * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc. | |
5 | * | |
86f5e6a7 FLVC |
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 | |
58687acb DZ |
9 | * to those contributors as well. |
10 | */ | |
11 | ||
4501980a AM |
12 | #define pr_fmt(fmt) "NMI watchdog: " fmt |
13 | ||
58687acb DZ |
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> | |
bcd951cf | 25 | #include <linux/smpboot.h> |
8bd75c77 | 26 | #include <linux/sched/rt.h> |
58687acb DZ |
27 | |
28 | #include <asm/irq_regs.h> | |
5d1c0f4a | 29 | #include <linux/kvm_para.h> |
58687acb DZ |
30 | #include <linux/perf_event.h> |
31 | ||
3c00ea82 | 32 | int watchdog_user_enabled = 1; |
4eec42f3 | 33 | int __read_mostly watchdog_thresh = 10; |
3c00ea82 | 34 | static int __read_mostly watchdog_running; |
0f34c400 | 35 | static u64 __read_mostly sample_period; |
58687acb DZ |
36 | |
37 | static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); | |
38 | static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog); | |
39 | static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer); | |
40 | static DEFINE_PER_CPU(bool, softlockup_touch_sync); | |
58687acb | 41 | static DEFINE_PER_CPU(bool, soft_watchdog_warn); |
bcd951cf TG |
42 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); |
43 | static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt); | |
23637d47 | 44 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
cafcd80d DZ |
45 | static DEFINE_PER_CPU(bool, hard_watchdog_warn); |
46 | static DEFINE_PER_CPU(bool, watchdog_nmi_touch); | |
58687acb DZ |
47 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); |
48 | static DEFINE_PER_CPU(struct perf_event *, watchdog_ev); | |
49 | #endif | |
50 | ||
58687acb DZ |
51 | /* boot commands */ |
52 | /* | |
53 | * Should we panic when a soft-lockup or hard-lockup occurs: | |
54 | */ | |
23637d47 | 55 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
fef2c9bc DZ |
56 | static int hardlockup_panic = |
57 | CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE; | |
58687acb DZ |
58 | |
59 | static int __init hardlockup_panic_setup(char *str) | |
60 | { | |
61 | if (!strncmp(str, "panic", 5)) | |
62 | hardlockup_panic = 1; | |
fef2c9bc DZ |
63 | else if (!strncmp(str, "nopanic", 7)) |
64 | hardlockup_panic = 0; | |
5dc30558 | 65 | else if (!strncmp(str, "0", 1)) |
3c00ea82 | 66 | watchdog_user_enabled = 0; |
58687acb DZ |
67 | return 1; |
68 | } | |
69 | __setup("nmi_watchdog=", hardlockup_panic_setup); | |
70 | #endif | |
71 | ||
72 | unsigned int __read_mostly softlockup_panic = | |
73 | CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE; | |
74 | ||
75 | static int __init softlockup_panic_setup(char *str) | |
76 | { | |
77 | softlockup_panic = simple_strtoul(str, NULL, 0); | |
78 | ||
79 | return 1; | |
80 | } | |
81 | __setup("softlockup_panic=", softlockup_panic_setup); | |
82 | ||
83 | static int __init nowatchdog_setup(char *str) | |
84 | { | |
3c00ea82 | 85 | watchdog_user_enabled = 0; |
58687acb DZ |
86 | return 1; |
87 | } | |
88 | __setup("nowatchdog", nowatchdog_setup); | |
89 | ||
90 | /* deprecated */ | |
91 | static int __init nosoftlockup_setup(char *str) | |
92 | { | |
3c00ea82 | 93 | watchdog_user_enabled = 0; |
58687acb DZ |
94 | return 1; |
95 | } | |
96 | __setup("nosoftlockup", nosoftlockup_setup); | |
97 | /* */ | |
98 | ||
4eec42f3 MSB |
99 | /* |
100 | * Hard-lockup warnings should be triggered after just a few seconds. Soft- | |
101 | * lockups can have false positives under extreme conditions. So we generally | |
102 | * want a higher threshold for soft lockups than for hard lockups. So we couple | |
103 | * the thresholds with a factor: we make the soft threshold twice the amount of | |
104 | * time the hard threshold is. | |
105 | */ | |
6e9101ae | 106 | static int get_softlockup_thresh(void) |
4eec42f3 MSB |
107 | { |
108 | return watchdog_thresh * 2; | |
109 | } | |
58687acb DZ |
110 | |
111 | /* | |
112 | * Returns seconds, approximately. We don't need nanosecond | |
113 | * resolution, and we don't need to waste time with a big divide when | |
114 | * 2^30ns == 1.074s. | |
115 | */ | |
c06b4f19 | 116 | static unsigned long get_timestamp(void) |
58687acb | 117 | { |
c06b4f19 | 118 | return local_clock() >> 30LL; /* 2^30 ~= 10^9 */ |
58687acb DZ |
119 | } |
120 | ||
0f34c400 | 121 | static void set_sample_period(void) |
58687acb DZ |
122 | { |
123 | /* | |
586692a5 | 124 | * convert watchdog_thresh from seconds to ns |
86f5e6a7 FLVC |
125 | * the divide by 5 is to give hrtimer several chances (two |
126 | * or three with the current relation between the soft | |
127 | * and hard thresholds) to increment before the | |
128 | * hardlockup detector generates a warning | |
58687acb | 129 | */ |
0f34c400 | 130 | sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); |
58687acb DZ |
131 | } |
132 | ||
133 | /* Commands for resetting the watchdog */ | |
134 | static void __touch_watchdog(void) | |
135 | { | |
c06b4f19 | 136 | __this_cpu_write(watchdog_touch_ts, get_timestamp()); |
58687acb DZ |
137 | } |
138 | ||
332fbdbc | 139 | void touch_softlockup_watchdog(void) |
58687acb | 140 | { |
7861144b AM |
141 | /* |
142 | * Preemption can be enabled. It doesn't matter which CPU's timestamp | |
143 | * gets zeroed here, so use the raw_ operation. | |
144 | */ | |
145 | raw_cpu_write(watchdog_touch_ts, 0); | |
58687acb | 146 | } |
0167c781 | 147 | EXPORT_SYMBOL(touch_softlockup_watchdog); |
58687acb | 148 | |
332fbdbc | 149 | void touch_all_softlockup_watchdogs(void) |
58687acb DZ |
150 | { |
151 | int cpu; | |
152 | ||
153 | /* | |
154 | * this is done lockless | |
155 | * do we care if a 0 races with a timestamp? | |
156 | * all it means is the softlock check starts one cycle later | |
157 | */ | |
158 | for_each_online_cpu(cpu) | |
159 | per_cpu(watchdog_touch_ts, cpu) = 0; | |
160 | } | |
161 | ||
cafcd80d | 162 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb DZ |
163 | void touch_nmi_watchdog(void) |
164 | { | |
62572e29 BZ |
165 | /* |
166 | * Using __raw here because some code paths have | |
167 | * preemption enabled. If preemption is enabled | |
168 | * then interrupts should be enabled too, in which | |
169 | * case we shouldn't have to worry about the watchdog | |
170 | * going off. | |
171 | */ | |
172 | __raw_get_cpu_var(watchdog_nmi_touch) = true; | |
332fbdbc | 173 | touch_softlockup_watchdog(); |
58687acb DZ |
174 | } |
175 | EXPORT_SYMBOL(touch_nmi_watchdog); | |
176 | ||
cafcd80d DZ |
177 | #endif |
178 | ||
58687acb DZ |
179 | void touch_softlockup_watchdog_sync(void) |
180 | { | |
181 | __raw_get_cpu_var(softlockup_touch_sync) = true; | |
182 | __raw_get_cpu_var(watchdog_touch_ts) = 0; | |
183 | } | |
184 | ||
23637d47 | 185 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb | 186 | /* watchdog detector functions */ |
26e09c6e | 187 | static int is_hardlockup(void) |
58687acb | 188 | { |
909ea964 | 189 | unsigned long hrint = __this_cpu_read(hrtimer_interrupts); |
58687acb | 190 | |
909ea964 | 191 | if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) |
58687acb DZ |
192 | return 1; |
193 | ||
909ea964 | 194 | __this_cpu_write(hrtimer_interrupts_saved, hrint); |
58687acb DZ |
195 | return 0; |
196 | } | |
197 | #endif | |
198 | ||
26e09c6e | 199 | static int is_softlockup(unsigned long touch_ts) |
58687acb | 200 | { |
c06b4f19 | 201 | unsigned long now = get_timestamp(); |
58687acb DZ |
202 | |
203 | /* Warn about unreasonable delays: */ | |
4eec42f3 | 204 | if (time_after(now, touch_ts + get_softlockup_thresh())) |
58687acb DZ |
205 | return now - touch_ts; |
206 | ||
207 | return 0; | |
208 | } | |
209 | ||
23637d47 | 210 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
1880c4ae | 211 | |
58687acb DZ |
212 | static struct perf_event_attr wd_hw_attr = { |
213 | .type = PERF_TYPE_HARDWARE, | |
214 | .config = PERF_COUNT_HW_CPU_CYCLES, | |
215 | .size = sizeof(struct perf_event_attr), | |
216 | .pinned = 1, | |
217 | .disabled = 1, | |
218 | }; | |
219 | ||
220 | /* Callback function for perf event subsystem */ | |
a8b0ca17 | 221 | static void watchdog_overflow_callback(struct perf_event *event, |
58687acb DZ |
222 | struct perf_sample_data *data, |
223 | struct pt_regs *regs) | |
224 | { | |
c6db67cd PZ |
225 | /* Ensure the watchdog never gets throttled */ |
226 | event->hw.interrupts = 0; | |
227 | ||
909ea964 CL |
228 | if (__this_cpu_read(watchdog_nmi_touch) == true) { |
229 | __this_cpu_write(watchdog_nmi_touch, false); | |
58687acb DZ |
230 | return; |
231 | } | |
232 | ||
233 | /* check for a hardlockup | |
234 | * This is done by making sure our timer interrupt | |
235 | * is incrementing. The timer interrupt should have | |
236 | * fired multiple times before we overflow'd. If it hasn't | |
237 | * then this is a good indication the cpu is stuck | |
238 | */ | |
26e09c6e DZ |
239 | if (is_hardlockup()) { |
240 | int this_cpu = smp_processor_id(); | |
241 | ||
58687acb | 242 | /* only print hardlockups once */ |
909ea964 | 243 | if (__this_cpu_read(hard_watchdog_warn) == true) |
58687acb DZ |
244 | return; |
245 | ||
246 | if (hardlockup_panic) | |
247 | panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu); | |
248 | else | |
249 | WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu); | |
250 | ||
909ea964 | 251 | __this_cpu_write(hard_watchdog_warn, true); |
58687acb DZ |
252 | return; |
253 | } | |
254 | ||
909ea964 | 255 | __this_cpu_write(hard_watchdog_warn, false); |
58687acb DZ |
256 | return; |
257 | } | |
bcd951cf TG |
258 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
259 | ||
58687acb DZ |
260 | static void watchdog_interrupt_count(void) |
261 | { | |
909ea964 | 262 | __this_cpu_inc(hrtimer_interrupts); |
58687acb | 263 | } |
bcd951cf TG |
264 | |
265 | static int watchdog_nmi_enable(unsigned int cpu); | |
266 | static void watchdog_nmi_disable(unsigned int cpu); | |
58687acb DZ |
267 | |
268 | /* watchdog kicker functions */ | |
269 | static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) | |
270 | { | |
909ea964 | 271 | unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts); |
58687acb DZ |
272 | struct pt_regs *regs = get_irq_regs(); |
273 | int duration; | |
274 | ||
275 | /* kick the hardlockup detector */ | |
276 | watchdog_interrupt_count(); | |
277 | ||
278 | /* kick the softlockup detector */ | |
909ea964 | 279 | wake_up_process(__this_cpu_read(softlockup_watchdog)); |
58687acb DZ |
280 | |
281 | /* .. and repeat */ | |
0f34c400 | 282 | hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period)); |
58687acb DZ |
283 | |
284 | if (touch_ts == 0) { | |
909ea964 | 285 | if (unlikely(__this_cpu_read(softlockup_touch_sync))) { |
58687acb DZ |
286 | /* |
287 | * If the time stamp was touched atomically | |
288 | * make sure the scheduler tick is up to date. | |
289 | */ | |
909ea964 | 290 | __this_cpu_write(softlockup_touch_sync, false); |
58687acb DZ |
291 | sched_clock_tick(); |
292 | } | |
5d1c0f4a EM |
293 | |
294 | /* Clear the guest paused flag on watchdog reset */ | |
295 | kvm_check_and_clear_guest_paused(); | |
58687acb DZ |
296 | __touch_watchdog(); |
297 | return HRTIMER_RESTART; | |
298 | } | |
299 | ||
300 | /* check for a softlockup | |
301 | * This is done by making sure a high priority task is | |
302 | * being scheduled. The task touches the watchdog to | |
303 | * indicate it is getting cpu time. If it hasn't then | |
304 | * this is a good indication some task is hogging the cpu | |
305 | */ | |
26e09c6e | 306 | duration = is_softlockup(touch_ts); |
58687acb | 307 | if (unlikely(duration)) { |
5d1c0f4a EM |
308 | /* |
309 | * If a virtual machine is stopped by the host it can look to | |
310 | * the watchdog like a soft lockup, check to see if the host | |
311 | * stopped the vm before we issue the warning | |
312 | */ | |
313 | if (kvm_check_and_clear_guest_paused()) | |
314 | return HRTIMER_RESTART; | |
315 | ||
58687acb | 316 | /* only warn once */ |
909ea964 | 317 | if (__this_cpu_read(soft_watchdog_warn) == true) |
58687acb DZ |
318 | return HRTIMER_RESTART; |
319 | ||
b0f4c4b3 | 320 | printk(KERN_EMERG "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", |
26e09c6e | 321 | smp_processor_id(), duration, |
58687acb DZ |
322 | current->comm, task_pid_nr(current)); |
323 | print_modules(); | |
324 | print_irqtrace_events(current); | |
325 | if (regs) | |
326 | show_regs(regs); | |
327 | else | |
328 | dump_stack(); | |
329 | ||
330 | if (softlockup_panic) | |
331 | panic("softlockup: hung tasks"); | |
909ea964 | 332 | __this_cpu_write(soft_watchdog_warn, true); |
58687acb | 333 | } else |
909ea964 | 334 | __this_cpu_write(soft_watchdog_warn, false); |
58687acb DZ |
335 | |
336 | return HRTIMER_RESTART; | |
337 | } | |
338 | ||
bcd951cf TG |
339 | static void watchdog_set_prio(unsigned int policy, unsigned int prio) |
340 | { | |
341 | struct sched_param param = { .sched_priority = prio }; | |
58687acb | 342 | |
bcd951cf TG |
343 | sched_setscheduler(current, policy, ¶m); |
344 | } | |
345 | ||
346 | static void watchdog_enable(unsigned int cpu) | |
58687acb | 347 | { |
26e09c6e | 348 | struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); |
58687acb | 349 | |
3935e895 BM |
350 | /* kick off the timer for the hardlockup detector */ |
351 | hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
352 | hrtimer->function = watchdog_timer_fn; | |
353 | ||
bcd951cf TG |
354 | /* Enable the perf event */ |
355 | watchdog_nmi_enable(cpu); | |
58687acb | 356 | |
58687acb | 357 | /* done here because hrtimer_start can only pin to smp_processor_id() */ |
0f34c400 | 358 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
58687acb DZ |
359 | HRTIMER_MODE_REL_PINNED); |
360 | ||
bcd951cf TG |
361 | /* initialize timestamp */ |
362 | watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1); | |
363 | __touch_watchdog(); | |
364 | } | |
58687acb | 365 | |
bcd951cf TG |
366 | static void watchdog_disable(unsigned int cpu) |
367 | { | |
368 | struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); | |
58687acb | 369 | |
bcd951cf TG |
370 | watchdog_set_prio(SCHED_NORMAL, 0); |
371 | hrtimer_cancel(hrtimer); | |
372 | /* disable the perf event */ | |
373 | watchdog_nmi_disable(cpu); | |
58687acb DZ |
374 | } |
375 | ||
b8900bc0 FW |
376 | static void watchdog_cleanup(unsigned int cpu, bool online) |
377 | { | |
378 | watchdog_disable(cpu); | |
379 | } | |
380 | ||
bcd951cf TG |
381 | static int watchdog_should_run(unsigned int cpu) |
382 | { | |
383 | return __this_cpu_read(hrtimer_interrupts) != | |
384 | __this_cpu_read(soft_lockup_hrtimer_cnt); | |
385 | } | |
386 | ||
387 | /* | |
388 | * The watchdog thread function - touches the timestamp. | |
389 | * | |
0f34c400 | 390 | * It only runs once every sample_period seconds (4 seconds by |
bcd951cf TG |
391 | * default) to reset the softlockup timestamp. If this gets delayed |
392 | * for more than 2*watchdog_thresh seconds then the debug-printout | |
393 | * triggers in watchdog_timer_fn(). | |
394 | */ | |
395 | static void watchdog(unsigned int cpu) | |
396 | { | |
397 | __this_cpu_write(soft_lockup_hrtimer_cnt, | |
398 | __this_cpu_read(hrtimer_interrupts)); | |
399 | __touch_watchdog(); | |
400 | } | |
58687acb | 401 | |
23637d47 | 402 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
a7027046 DZ |
403 | /* |
404 | * People like the simple clean cpu node info on boot. | |
405 | * Reduce the watchdog noise by only printing messages | |
406 | * that are different from what cpu0 displayed. | |
407 | */ | |
408 | static unsigned long cpu0_err; | |
409 | ||
bcd951cf | 410 | static int watchdog_nmi_enable(unsigned int cpu) |
58687acb DZ |
411 | { |
412 | struct perf_event_attr *wd_attr; | |
413 | struct perf_event *event = per_cpu(watchdog_ev, cpu); | |
414 | ||
415 | /* is it already setup and enabled? */ | |
416 | if (event && event->state > PERF_EVENT_STATE_OFF) | |
417 | goto out; | |
418 | ||
419 | /* it is setup but not enabled */ | |
420 | if (event != NULL) | |
421 | goto out_enable; | |
422 | ||
58687acb | 423 | wd_attr = &wd_hw_attr; |
4eec42f3 | 424 | wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); |
1880c4ae CG |
425 | |
426 | /* Try to register using hardware perf events */ | |
4dc0da86 | 427 | event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL); |
a7027046 DZ |
428 | |
429 | /* save cpu0 error for future comparision */ | |
430 | if (cpu == 0 && IS_ERR(event)) | |
431 | cpu0_err = PTR_ERR(event); | |
432 | ||
58687acb | 433 | if (!IS_ERR(event)) { |
a7027046 DZ |
434 | /* only print for cpu0 or different than cpu0 */ |
435 | if (cpu == 0 || cpu0_err) | |
436 | pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n"); | |
58687acb DZ |
437 | goto out_save; |
438 | } | |
439 | ||
a7027046 DZ |
440 | /* skip displaying the same error again */ |
441 | if (cpu > 0 && (PTR_ERR(event) == cpu0_err)) | |
442 | return PTR_ERR(event); | |
5651f7f4 DZ |
443 | |
444 | /* vary the KERN level based on the returned errno */ | |
445 | if (PTR_ERR(event) == -EOPNOTSUPP) | |
4501980a | 446 | pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu); |
5651f7f4 | 447 | else if (PTR_ERR(event) == -ENOENT) |
4501980a AM |
448 | pr_warning("disabled (cpu%i): hardware events not enabled\n", |
449 | cpu); | |
5651f7f4 | 450 | else |
4501980a AM |
451 | pr_err("disabled (cpu%i): unable to create perf event: %ld\n", |
452 | cpu, PTR_ERR(event)); | |
eac24335 | 453 | return PTR_ERR(event); |
58687acb DZ |
454 | |
455 | /* success path */ | |
456 | out_save: | |
457 | per_cpu(watchdog_ev, cpu) = event; | |
458 | out_enable: | |
459 | perf_event_enable(per_cpu(watchdog_ev, cpu)); | |
460 | out: | |
461 | return 0; | |
462 | } | |
463 | ||
bcd951cf | 464 | static void watchdog_nmi_disable(unsigned int cpu) |
58687acb DZ |
465 | { |
466 | struct perf_event *event = per_cpu(watchdog_ev, cpu); | |
467 | ||
468 | if (event) { | |
469 | perf_event_disable(event); | |
470 | per_cpu(watchdog_ev, cpu) = NULL; | |
471 | ||
472 | /* should be in cleanup, but blocks oprofile */ | |
473 | perf_event_release_kernel(event); | |
474 | } | |
475 | return; | |
476 | } | |
477 | #else | |
bcd951cf TG |
478 | static int watchdog_nmi_enable(unsigned int cpu) { return 0; } |
479 | static void watchdog_nmi_disable(unsigned int cpu) { return; } | |
23637d47 | 480 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
58687acb | 481 | |
b8900bc0 FW |
482 | static struct smp_hotplug_thread watchdog_threads = { |
483 | .store = &softlockup_watchdog, | |
484 | .thread_should_run = watchdog_should_run, | |
485 | .thread_fn = watchdog, | |
486 | .thread_comm = "watchdog/%u", | |
487 | .setup = watchdog_enable, | |
488 | .cleanup = watchdog_cleanup, | |
489 | .park = watchdog_disable, | |
490 | .unpark = watchdog_enable, | |
491 | }; | |
492 | ||
9809b18f MH |
493 | static void restart_watchdog_hrtimer(void *info) |
494 | { | |
495 | struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); | |
496 | int ret; | |
497 | ||
498 | /* | |
499 | * No need to cancel and restart hrtimer if it is currently executing | |
500 | * because it will reprogram itself with the new period now. | |
501 | * We should never see it unqueued here because we are running per-cpu | |
502 | * with interrupts disabled. | |
503 | */ | |
504 | ret = hrtimer_try_to_cancel(hrtimer); | |
505 | if (ret == 1) | |
506 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), | |
507 | HRTIMER_MODE_REL_PINNED); | |
508 | } | |
509 | ||
510 | static void update_timers(int cpu) | |
511 | { | |
9809b18f MH |
512 | /* |
513 | * Make sure that perf event counter will adopt to a new | |
514 | * sampling period. Updating the sampling period directly would | |
515 | * be much nicer but we do not have an API for that now so | |
516 | * let's use a big hammer. | |
517 | * Hrtimer will adopt the new period on the next tick but this | |
518 | * might be late already so we have to restart the timer as well. | |
519 | */ | |
520 | watchdog_nmi_disable(cpu); | |
e0a23b06 | 521 | smp_call_function_single(cpu, restart_watchdog_hrtimer, NULL, 1); |
9809b18f MH |
522 | watchdog_nmi_enable(cpu); |
523 | } | |
524 | ||
525 | static void update_timers_all_cpus(void) | |
526 | { | |
527 | int cpu; | |
528 | ||
529 | get_online_cpus(); | |
530 | preempt_disable(); | |
531 | for_each_online_cpu(cpu) | |
532 | update_timers(cpu); | |
533 | preempt_enable(); | |
534 | put_online_cpus(); | |
535 | } | |
536 | ||
537 | static int watchdog_enable_all_cpus(bool sample_period_changed) | |
58687acb | 538 | { |
b8900bc0 | 539 | int err = 0; |
58687acb | 540 | |
3c00ea82 | 541 | if (!watchdog_running) { |
b8900bc0 FW |
542 | err = smpboot_register_percpu_thread(&watchdog_threads); |
543 | if (err) | |
544 | pr_err("Failed to create watchdog threads, disabled\n"); | |
545 | else | |
3c00ea82 | 546 | watchdog_running = 1; |
9809b18f MH |
547 | } else if (sample_period_changed) { |
548 | update_timers_all_cpus(); | |
bcd951cf | 549 | } |
b8900bc0 FW |
550 | |
551 | return err; | |
58687acb DZ |
552 | } |
553 | ||
b8900bc0 FW |
554 | /* prepare/enable/disable routines */ |
555 | /* sysctl functions */ | |
556 | #ifdef CONFIG_SYSCTL | |
58687acb DZ |
557 | static void watchdog_disable_all_cpus(void) |
558 | { | |
3c00ea82 FW |
559 | if (watchdog_running) { |
560 | watchdog_running = 0; | |
b8900bc0 | 561 | smpboot_unregister_percpu_thread(&watchdog_threads); |
bcd951cf | 562 | } |
58687acb DZ |
563 | } |
564 | ||
58687acb | 565 | /* |
586692a5 | 566 | * proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh |
58687acb DZ |
567 | */ |
568 | ||
586692a5 MSB |
569 | int proc_dowatchdog(struct ctl_table *table, int write, |
570 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
58687acb | 571 | { |
b8900bc0 | 572 | int err, old_thresh, old_enabled; |
359e6fab | 573 | static DEFINE_MUTEX(watchdog_proc_mutex); |
58687acb | 574 | |
359e6fab | 575 | mutex_lock(&watchdog_proc_mutex); |
b8900bc0 | 576 | old_thresh = ACCESS_ONCE(watchdog_thresh); |
3c00ea82 | 577 | old_enabled = ACCESS_ONCE(watchdog_user_enabled); |
bcd951cf | 578 | |
b8900bc0 FW |
579 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
580 | if (err || !write) | |
359e6fab | 581 | goto out; |
e04ab2bc | 582 | |
0f34c400 | 583 | set_sample_period(); |
b66a2356 | 584 | /* |
585 | * Watchdog threads shouldn't be enabled if they are | |
3c00ea82 | 586 | * disabled. The 'watchdog_running' variable check in |
b66a2356 | 587 | * watchdog_*_all_cpus() function takes care of this. |
588 | */ | |
3c00ea82 | 589 | if (watchdog_user_enabled && watchdog_thresh) |
9809b18f | 590 | err = watchdog_enable_all_cpus(old_thresh != watchdog_thresh); |
e04ab2bc MSB |
591 | else |
592 | watchdog_disable_all_cpus(); | |
593 | ||
b8900bc0 FW |
594 | /* Restore old values on failure */ |
595 | if (err) { | |
596 | watchdog_thresh = old_thresh; | |
3c00ea82 | 597 | watchdog_user_enabled = old_enabled; |
b8900bc0 | 598 | } |
359e6fab MH |
599 | out: |
600 | mutex_unlock(&watchdog_proc_mutex); | |
b8900bc0 | 601 | return err; |
58687acb | 602 | } |
58687acb DZ |
603 | #endif /* CONFIG_SYSCTL */ |
604 | ||
004417a6 | 605 | void __init lockup_detector_init(void) |
58687acb | 606 | { |
0f34c400 | 607 | set_sample_period(); |
b8900bc0 | 608 | |
3c00ea82 | 609 | if (watchdog_user_enabled) |
9809b18f | 610 | watchdog_enable_all_cpus(false); |
58687acb | 611 | } |