Commit | Line | Data |
---|---|---|
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 | ||
4135038a | 32 | int watchdog_enabled = 1; |
4eec42f3 | 33 | int __read_mostly watchdog_thresh = 10; |
bcd951cf | 34 | static int __read_mostly watchdog_disabled; |
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 | 47 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); |
6fa3eb70 S |
48 | #endif |
49 | #ifdef CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU | |
50 | static cpumask_t __read_mostly watchdog_cpus; | |
51 | #endif | |
52 | #ifdef CONFIG_HARDLOCKUP_DETECTOR_NMI | |
58687acb DZ |
53 | static DEFINE_PER_CPU(struct perf_event *, watchdog_ev); |
54 | #endif | |
55 | ||
58687acb DZ |
56 | /* boot commands */ |
57 | /* | |
58 | * Should we panic when a soft-lockup or hard-lockup occurs: | |
59 | */ | |
23637d47 | 60 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
fef2c9bc DZ |
61 | static int hardlockup_panic = |
62 | CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE; | |
58687acb DZ |
63 | |
64 | static int __init hardlockup_panic_setup(char *str) | |
65 | { | |
66 | if (!strncmp(str, "panic", 5)) | |
67 | hardlockup_panic = 1; | |
fef2c9bc DZ |
68 | else if (!strncmp(str, "nopanic", 7)) |
69 | hardlockup_panic = 0; | |
5dc30558 | 70 | else if (!strncmp(str, "0", 1)) |
4135038a | 71 | watchdog_enabled = 0; |
58687acb DZ |
72 | return 1; |
73 | } | |
74 | __setup("nmi_watchdog=", hardlockup_panic_setup); | |
75 | #endif | |
76 | ||
77 | unsigned int __read_mostly softlockup_panic = | |
78 | CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE; | |
79 | ||
80 | static int __init softlockup_panic_setup(char *str) | |
81 | { | |
82 | softlockup_panic = simple_strtoul(str, NULL, 0); | |
83 | ||
84 | return 1; | |
85 | } | |
86 | __setup("softlockup_panic=", softlockup_panic_setup); | |
87 | ||
88 | static int __init nowatchdog_setup(char *str) | |
89 | { | |
4135038a | 90 | watchdog_enabled = 0; |
58687acb DZ |
91 | return 1; |
92 | } | |
93 | __setup("nowatchdog", nowatchdog_setup); | |
94 | ||
95 | /* deprecated */ | |
96 | static int __init nosoftlockup_setup(char *str) | |
97 | { | |
4135038a | 98 | watchdog_enabled = 0; |
58687acb DZ |
99 | return 1; |
100 | } | |
101 | __setup("nosoftlockup", nosoftlockup_setup); | |
102 | /* */ | |
103 | ||
4eec42f3 MSB |
104 | /* |
105 | * Hard-lockup warnings should be triggered after just a few seconds. Soft- | |
106 | * lockups can have false positives under extreme conditions. So we generally | |
107 | * want a higher threshold for soft lockups than for hard lockups. So we couple | |
108 | * the thresholds with a factor: we make the soft threshold twice the amount of | |
109 | * time the hard threshold is. | |
110 | */ | |
6e9101ae | 111 | static int get_softlockup_thresh(void) |
4eec42f3 MSB |
112 | { |
113 | return watchdog_thresh * 2; | |
114 | } | |
58687acb DZ |
115 | |
116 | /* | |
117 | * Returns seconds, approximately. We don't need nanosecond | |
118 | * resolution, and we don't need to waste time with a big divide when | |
119 | * 2^30ns == 1.074s. | |
120 | */ | |
c06b4f19 | 121 | static unsigned long get_timestamp(void) |
58687acb | 122 | { |
c06b4f19 | 123 | return local_clock() >> 30LL; /* 2^30 ~= 10^9 */ |
58687acb DZ |
124 | } |
125 | ||
0f34c400 | 126 | static void set_sample_period(void) |
58687acb DZ |
127 | { |
128 | /* | |
586692a5 | 129 | * convert watchdog_thresh from seconds to ns |
86f5e6a7 FLVC |
130 | * the divide by 5 is to give hrtimer several chances (two |
131 | * or three with the current relation between the soft | |
132 | * and hard thresholds) to increment before the | |
133 | * hardlockup detector generates a warning | |
58687acb | 134 | */ |
0f34c400 | 135 | sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); |
58687acb DZ |
136 | } |
137 | ||
138 | /* Commands for resetting the watchdog */ | |
139 | static void __touch_watchdog(void) | |
140 | { | |
c06b4f19 | 141 | __this_cpu_write(watchdog_touch_ts, get_timestamp()); |
58687acb DZ |
142 | } |
143 | ||
332fbdbc | 144 | void touch_softlockup_watchdog(void) |
58687acb | 145 | { |
909ea964 | 146 | __this_cpu_write(watchdog_touch_ts, 0); |
58687acb | 147 | } |
0167c781 | 148 | EXPORT_SYMBOL(touch_softlockup_watchdog); |
58687acb | 149 | |
332fbdbc | 150 | void touch_all_softlockup_watchdogs(void) |
58687acb DZ |
151 | { |
152 | int cpu; | |
153 | ||
154 | /* | |
155 | * this is done lockless | |
156 | * do we care if a 0 races with a timestamp? | |
157 | * all it means is the softlock check starts one cycle later | |
158 | */ | |
159 | for_each_online_cpu(cpu) | |
160 | per_cpu(watchdog_touch_ts, cpu) = 0; | |
161 | } | |
162 | ||
cafcd80d | 163 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb DZ |
164 | void touch_nmi_watchdog(void) |
165 | { | |
68d3f1d8 DZ |
166 | if (watchdog_enabled) { |
167 | unsigned cpu; | |
168 | ||
169 | for_each_present_cpu(cpu) { | |
170 | if (per_cpu(watchdog_nmi_touch, cpu) != true) | |
171 | per_cpu(watchdog_nmi_touch, cpu) = true; | |
172 | } | |
173 | } | |
332fbdbc | 174 | touch_softlockup_watchdog(); |
58687acb DZ |
175 | } |
176 | EXPORT_SYMBOL(touch_nmi_watchdog); | |
177 | ||
cafcd80d DZ |
178 | #endif |
179 | ||
58687acb DZ |
180 | void touch_softlockup_watchdog_sync(void) |
181 | { | |
182 | __raw_get_cpu_var(softlockup_touch_sync) = true; | |
183 | __raw_get_cpu_var(watchdog_touch_ts) = 0; | |
184 | } | |
185 | ||
6fa3eb70 | 186 | #ifdef CONFIG_HARDLOCKUP_DETECTOR_NMI |
58687acb | 187 | /* watchdog detector functions */ |
26e09c6e | 188 | static int is_hardlockup(void) |
58687acb | 189 | { |
909ea964 | 190 | unsigned long hrint = __this_cpu_read(hrtimer_interrupts); |
58687acb | 191 | |
909ea964 | 192 | if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) |
58687acb DZ |
193 | return 1; |
194 | ||
909ea964 | 195 | __this_cpu_write(hrtimer_interrupts_saved, hrint); |
58687acb DZ |
196 | return 0; |
197 | } | |
198 | #endif | |
199 | ||
6fa3eb70 S |
200 | #ifdef CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU |
201 | static unsigned int watchdog_next_cpu(unsigned int cpu) | |
202 | { | |
203 | cpumask_t cpus = watchdog_cpus; | |
204 | unsigned int next_cpu; | |
205 | ||
206 | next_cpu = cpumask_next(cpu, &cpus); | |
207 | if (next_cpu >= nr_cpu_ids) | |
208 | next_cpu = cpumask_first(&cpus); | |
209 | ||
210 | if (next_cpu == cpu) | |
211 | return nr_cpu_ids; | |
212 | ||
213 | return next_cpu; | |
214 | } | |
215 | ||
216 | static int is_hardlockup_other_cpu(unsigned int cpu) | |
217 | { | |
218 | unsigned long hrint = per_cpu(hrtimer_interrupts, cpu); | |
219 | ||
220 | if (per_cpu(hrtimer_interrupts_saved, cpu) == hrint) | |
221 | return 1; | |
222 | ||
223 | per_cpu(hrtimer_interrupts_saved, cpu) = hrint; | |
224 | return 0; | |
225 | } | |
226 | ||
227 | static void watchdog_check_hardlockup_other_cpu(void) | |
228 | { | |
229 | unsigned int next_cpu; | |
230 | ||
231 | /* | |
232 | * Test for hardlockups every 3 samples. The sample period is | |
233 | * watchdog_thresh * 2 / 5, so 3 samples gets us back to slightly over | |
234 | * watchdog_thresh (over by 20%). | |
235 | */ | |
236 | if (__this_cpu_read(hrtimer_interrupts) % 3 != 0) | |
237 | return; | |
238 | ||
239 | /* check for a hardlockup on the next cpu */ | |
240 | next_cpu = watchdog_next_cpu(smp_processor_id()); | |
241 | if (next_cpu >= nr_cpu_ids) | |
242 | return; | |
243 | ||
244 | smp_rmb(); | |
245 | ||
246 | if (per_cpu(watchdog_nmi_touch, next_cpu) == true) { | |
247 | per_cpu(watchdog_nmi_touch, next_cpu) = false; | |
248 | return; | |
249 | } | |
250 | ||
251 | if (is_hardlockup_other_cpu(next_cpu)) { | |
252 | /* only warn once */ | |
253 | if (per_cpu(hard_watchdog_warn, next_cpu) == true) | |
254 | return; | |
255 | ||
256 | if (hardlockup_panic) | |
257 | panic("Watchdog detected hard LOCKUP on cpu %u", next_cpu); | |
258 | else | |
259 | WARN(1, "Watchdog detected hard LOCKUP on cpu %u", next_cpu); | |
260 | ||
261 | per_cpu(hard_watchdog_warn, next_cpu) = true; | |
262 | } else { | |
263 | per_cpu(hard_watchdog_warn, next_cpu) = false; | |
264 | } | |
265 | } | |
266 | #else | |
267 | static inline void watchdog_check_hardlockup_other_cpu(void) { return; } | |
268 | #endif | |
269 | ||
26e09c6e | 270 | static int is_softlockup(unsigned long touch_ts) |
58687acb | 271 | { |
c06b4f19 | 272 | unsigned long now = get_timestamp(); |
58687acb DZ |
273 | |
274 | /* Warn about unreasonable delays: */ | |
4eec42f3 | 275 | if (time_after(now, touch_ts + get_softlockup_thresh())) |
58687acb DZ |
276 | return now - touch_ts; |
277 | ||
278 | return 0; | |
279 | } | |
280 | ||
6fa3eb70 | 281 | #ifdef CONFIG_HARDLOCKUP_DETECTOR_NMI |
1880c4ae | 282 | |
58687acb DZ |
283 | static struct perf_event_attr wd_hw_attr = { |
284 | .type = PERF_TYPE_HARDWARE, | |
285 | .config = PERF_COUNT_HW_CPU_CYCLES, | |
286 | .size = sizeof(struct perf_event_attr), | |
287 | .pinned = 1, | |
288 | .disabled = 1, | |
289 | }; | |
290 | ||
291 | /* Callback function for perf event subsystem */ | |
a8b0ca17 | 292 | static void watchdog_overflow_callback(struct perf_event *event, |
58687acb DZ |
293 | struct perf_sample_data *data, |
294 | struct pt_regs *regs) | |
295 | { | |
c6db67cd PZ |
296 | /* Ensure the watchdog never gets throttled */ |
297 | event->hw.interrupts = 0; | |
298 | ||
909ea964 CL |
299 | if (__this_cpu_read(watchdog_nmi_touch) == true) { |
300 | __this_cpu_write(watchdog_nmi_touch, false); | |
58687acb DZ |
301 | return; |
302 | } | |
303 | ||
304 | /* check for a hardlockup | |
305 | * This is done by making sure our timer interrupt | |
306 | * is incrementing. The timer interrupt should have | |
307 | * fired multiple times before we overflow'd. If it hasn't | |
308 | * then this is a good indication the cpu is stuck | |
309 | */ | |
26e09c6e DZ |
310 | if (is_hardlockup()) { |
311 | int this_cpu = smp_processor_id(); | |
312 | ||
58687acb | 313 | /* only print hardlockups once */ |
909ea964 | 314 | if (__this_cpu_read(hard_watchdog_warn) == true) |
58687acb DZ |
315 | return; |
316 | ||
317 | if (hardlockup_panic) | |
318 | panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu); | |
319 | else | |
320 | WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu); | |
321 | ||
909ea964 | 322 | __this_cpu_write(hard_watchdog_warn, true); |
58687acb DZ |
323 | return; |
324 | } | |
325 | ||
909ea964 | 326 | __this_cpu_write(hard_watchdog_warn, false); |
58687acb DZ |
327 | return; |
328 | } | |
6fa3eb70 | 329 | #endif /* CONFIG_HARDLOCKUP_DETECTOR_NMI */ |
bcd951cf | 330 | |
58687acb DZ |
331 | static void watchdog_interrupt_count(void) |
332 | { | |
909ea964 | 333 | __this_cpu_inc(hrtimer_interrupts); |
58687acb | 334 | } |
bcd951cf TG |
335 | |
336 | static int watchdog_nmi_enable(unsigned int cpu); | |
337 | static void watchdog_nmi_disable(unsigned int cpu); | |
58687acb DZ |
338 | |
339 | /* watchdog kicker functions */ | |
340 | static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) | |
341 | { | |
909ea964 | 342 | unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts); |
58687acb DZ |
343 | struct pt_regs *regs = get_irq_regs(); |
344 | int duration; | |
345 | ||
346 | /* kick the hardlockup detector */ | |
347 | watchdog_interrupt_count(); | |
348 | ||
6fa3eb70 S |
349 | /* test for hardlockups on the next cpu */ |
350 | watchdog_check_hardlockup_other_cpu(); | |
351 | ||
58687acb | 352 | /* kick the softlockup detector */ |
909ea964 | 353 | wake_up_process(__this_cpu_read(softlockup_watchdog)); |
58687acb DZ |
354 | |
355 | /* .. and repeat */ | |
0f34c400 | 356 | hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period)); |
58687acb DZ |
357 | |
358 | if (touch_ts == 0) { | |
909ea964 | 359 | if (unlikely(__this_cpu_read(softlockup_touch_sync))) { |
58687acb DZ |
360 | /* |
361 | * If the time stamp was touched atomically | |
362 | * make sure the scheduler tick is up to date. | |
363 | */ | |
909ea964 | 364 | __this_cpu_write(softlockup_touch_sync, false); |
58687acb DZ |
365 | sched_clock_tick(); |
366 | } | |
5d1c0f4a EM |
367 | |
368 | /* Clear the guest paused flag on watchdog reset */ | |
369 | kvm_check_and_clear_guest_paused(); | |
58687acb DZ |
370 | __touch_watchdog(); |
371 | return HRTIMER_RESTART; | |
372 | } | |
373 | ||
374 | /* check for a softlockup | |
375 | * This is done by making sure a high priority task is | |
376 | * being scheduled. The task touches the watchdog to | |
377 | * indicate it is getting cpu time. If it hasn't then | |
378 | * this is a good indication some task is hogging the cpu | |
379 | */ | |
26e09c6e | 380 | duration = is_softlockup(touch_ts); |
58687acb | 381 | if (unlikely(duration)) { |
5d1c0f4a EM |
382 | /* |
383 | * If a virtual machine is stopped by the host it can look to | |
384 | * the watchdog like a soft lockup, check to see if the host | |
385 | * stopped the vm before we issue the warning | |
386 | */ | |
387 | if (kvm_check_and_clear_guest_paused()) | |
388 | return HRTIMER_RESTART; | |
389 | ||
58687acb | 390 | /* only warn once */ |
909ea964 | 391 | if (__this_cpu_read(soft_watchdog_warn) == true) |
58687acb DZ |
392 | return HRTIMER_RESTART; |
393 | ||
b0f4c4b3 | 394 | printk(KERN_EMERG "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", |
26e09c6e | 395 | smp_processor_id(), duration, |
58687acb DZ |
396 | current->comm, task_pid_nr(current)); |
397 | print_modules(); | |
398 | print_irqtrace_events(current); | |
399 | if (regs) | |
400 | show_regs(regs); | |
401 | else | |
402 | dump_stack(); | |
403 | ||
404 | if (softlockup_panic) | |
405 | panic("softlockup: hung tasks"); | |
909ea964 | 406 | __this_cpu_write(soft_watchdog_warn, true); |
58687acb | 407 | } else |
909ea964 | 408 | __this_cpu_write(soft_watchdog_warn, false); |
58687acb DZ |
409 | |
410 | return HRTIMER_RESTART; | |
411 | } | |
412 | ||
bcd951cf TG |
413 | static void watchdog_set_prio(unsigned int policy, unsigned int prio) |
414 | { | |
415 | struct sched_param param = { .sched_priority = prio }; | |
58687acb | 416 | |
bcd951cf TG |
417 | sched_setscheduler(current, policy, ¶m); |
418 | } | |
419 | ||
420 | static void watchdog_enable(unsigned int cpu) | |
58687acb | 421 | { |
26e09c6e | 422 | struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); |
58687acb | 423 | |
3935e895 BM |
424 | /* kick off the timer for the hardlockup detector */ |
425 | hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
426 | hrtimer->function = watchdog_timer_fn; | |
427 | ||
bcd951cf TG |
428 | if (!watchdog_enabled) { |
429 | kthread_park(current); | |
430 | return; | |
431 | } | |
432 | ||
433 | /* Enable the perf event */ | |
434 | watchdog_nmi_enable(cpu); | |
58687acb | 435 | |
58687acb | 436 | /* done here because hrtimer_start can only pin to smp_processor_id() */ |
0f34c400 | 437 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
58687acb DZ |
438 | HRTIMER_MODE_REL_PINNED); |
439 | ||
bcd951cf TG |
440 | /* initialize timestamp */ |
441 | watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1); | |
442 | __touch_watchdog(); | |
443 | } | |
58687acb | 444 | |
bcd951cf TG |
445 | static void watchdog_disable(unsigned int cpu) |
446 | { | |
447 | struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); | |
58687acb | 448 | |
bcd951cf TG |
449 | watchdog_set_prio(SCHED_NORMAL, 0); |
450 | hrtimer_cancel(hrtimer); | |
451 | /* disable the perf event */ | |
452 | watchdog_nmi_disable(cpu); | |
58687acb DZ |
453 | } |
454 | ||
bcd951cf TG |
455 | static int watchdog_should_run(unsigned int cpu) |
456 | { | |
457 | return __this_cpu_read(hrtimer_interrupts) != | |
458 | __this_cpu_read(soft_lockup_hrtimer_cnt); | |
459 | } | |
460 | ||
461 | /* | |
462 | * The watchdog thread function - touches the timestamp. | |
463 | * | |
0f34c400 | 464 | * It only runs once every sample_period seconds (4 seconds by |
bcd951cf TG |
465 | * default) to reset the softlockup timestamp. If this gets delayed |
466 | * for more than 2*watchdog_thresh seconds then the debug-printout | |
467 | * triggers in watchdog_timer_fn(). | |
468 | */ | |
469 | static void watchdog(unsigned int cpu) | |
470 | { | |
471 | __this_cpu_write(soft_lockup_hrtimer_cnt, | |
472 | __this_cpu_read(hrtimer_interrupts)); | |
473 | __touch_watchdog(); | |
474 | } | |
58687acb | 475 | |
6fa3eb70 | 476 | #ifdef CONFIG_HARDLOCKUP_DETECTOR_NMI |
a7027046 DZ |
477 | /* |
478 | * People like the simple clean cpu node info on boot. | |
479 | * Reduce the watchdog noise by only printing messages | |
480 | * that are different from what cpu0 displayed. | |
481 | */ | |
482 | static unsigned long cpu0_err; | |
483 | ||
bcd951cf | 484 | static int watchdog_nmi_enable(unsigned int cpu) |
58687acb DZ |
485 | { |
486 | struct perf_event_attr *wd_attr; | |
487 | struct perf_event *event = per_cpu(watchdog_ev, cpu); | |
488 | ||
489 | /* is it already setup and enabled? */ | |
490 | if (event && event->state > PERF_EVENT_STATE_OFF) | |
491 | goto out; | |
492 | ||
493 | /* it is setup but not enabled */ | |
494 | if (event != NULL) | |
495 | goto out_enable; | |
496 | ||
58687acb | 497 | wd_attr = &wd_hw_attr; |
4eec42f3 | 498 | wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); |
1880c4ae CG |
499 | |
500 | /* Try to register using hardware perf events */ | |
4dc0da86 | 501 | event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL); |
a7027046 DZ |
502 | |
503 | /* save cpu0 error for future comparision */ | |
504 | if (cpu == 0 && IS_ERR(event)) | |
505 | cpu0_err = PTR_ERR(event); | |
506 | ||
58687acb | 507 | if (!IS_ERR(event)) { |
a7027046 DZ |
508 | /* only print for cpu0 or different than cpu0 */ |
509 | if (cpu == 0 || cpu0_err) | |
510 | pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n"); | |
58687acb DZ |
511 | goto out_save; |
512 | } | |
513 | ||
a7027046 DZ |
514 | /* skip displaying the same error again */ |
515 | if (cpu > 0 && (PTR_ERR(event) == cpu0_err)) | |
516 | return PTR_ERR(event); | |
5651f7f4 DZ |
517 | |
518 | /* vary the KERN level based on the returned errno */ | |
519 | if (PTR_ERR(event) == -EOPNOTSUPP) | |
4501980a | 520 | pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu); |
5651f7f4 | 521 | else if (PTR_ERR(event) == -ENOENT) |
4501980a AM |
522 | pr_warning("disabled (cpu%i): hardware events not enabled\n", |
523 | cpu); | |
5651f7f4 | 524 | else |
4501980a AM |
525 | pr_err("disabled (cpu%i): unable to create perf event: %ld\n", |
526 | cpu, PTR_ERR(event)); | |
eac24335 | 527 | return PTR_ERR(event); |
58687acb DZ |
528 | |
529 | /* success path */ | |
530 | out_save: | |
531 | per_cpu(watchdog_ev, cpu) = event; | |
532 | out_enable: | |
533 | perf_event_enable(per_cpu(watchdog_ev, cpu)); | |
534 | out: | |
535 | return 0; | |
536 | } | |
537 | ||
bcd951cf | 538 | static void watchdog_nmi_disable(unsigned int cpu) |
58687acb DZ |
539 | { |
540 | struct perf_event *event = per_cpu(watchdog_ev, cpu); | |
541 | ||
542 | if (event) { | |
543 | perf_event_disable(event); | |
544 | per_cpu(watchdog_ev, cpu) = NULL; | |
545 | ||
546 | /* should be in cleanup, but blocks oprofile */ | |
547 | perf_event_release_kernel(event); | |
548 | } | |
549 | return; | |
550 | } | |
551 | #else | |
6fa3eb70 S |
552 | #ifdef CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU |
553 | static int watchdog_nmi_enable(unsigned int cpu) | |
554 | { | |
555 | /* | |
556 | * The new cpu will be marked online before the first hrtimer interrupt | |
557 | * runs on it. If another cpu tests for a hardlockup on the new cpu | |
558 | * before it has run its first hrtimer, it will get a false positive. | |
559 | * Touch the watchdog on the new cpu to delay the first check for at | |
560 | * least 3 sampling periods to guarantee one hrtimer has run on the new | |
561 | * cpu. | |
562 | */ | |
563 | per_cpu(watchdog_nmi_touch, cpu) = true; | |
564 | smp_wmb(); | |
565 | cpumask_set_cpu(cpu, &watchdog_cpus); | |
566 | return 0; | |
567 | } | |
568 | ||
569 | static void watchdog_nmi_disable(unsigned int cpu) | |
570 | { | |
571 | unsigned int next_cpu = watchdog_next_cpu(cpu); | |
572 | ||
573 | /* | |
574 | * Offlining this cpu will cause the cpu before this one to start | |
575 | * checking the one after this one. If this cpu just finished checking | |
576 | * the next cpu and updating hrtimer_interrupts_saved, and then the | |
577 | * previous cpu checks it within one sample period, it will trigger a | |
578 | * false positive. Touch the watchdog on the next cpu to prevent it. | |
579 | */ | |
580 | if (next_cpu < nr_cpu_ids) | |
581 | per_cpu(watchdog_nmi_touch, next_cpu) = true; | |
582 | smp_wmb(); | |
583 | cpumask_clear_cpu(cpu, &watchdog_cpus); | |
584 | } | |
585 | #else | |
bcd951cf TG |
586 | static int watchdog_nmi_enable(unsigned int cpu) { return 0; } |
587 | static void watchdog_nmi_disable(unsigned int cpu) { return; } | |
6fa3eb70 S |
588 | #endif /* CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU */ |
589 | #endif /* CONFIG_HARDLOCKUP_DETECTOR_NMI */ | |
58687acb DZ |
590 | |
591 | /* prepare/enable/disable routines */ | |
4ff81951 VA |
592 | /* sysctl functions */ |
593 | #ifdef CONFIG_SYSCTL | |
58687acb DZ |
594 | static void watchdog_enable_all_cpus(void) |
595 | { | |
bcd951cf | 596 | unsigned int cpu; |
58687acb | 597 | |
bcd951cf TG |
598 | if (watchdog_disabled) { |
599 | watchdog_disabled = 0; | |
600 | for_each_online_cpu(cpu) | |
601 | kthread_unpark(per_cpu(softlockup_watchdog, cpu)); | |
602 | } | |
58687acb DZ |
603 | } |
604 | ||
605 | static void watchdog_disable_all_cpus(void) | |
606 | { | |
bcd951cf | 607 | unsigned int cpu; |
58687acb | 608 | |
bcd951cf TG |
609 | if (!watchdog_disabled) { |
610 | watchdog_disabled = 1; | |
611 | for_each_online_cpu(cpu) | |
612 | kthread_park(per_cpu(softlockup_watchdog, cpu)); | |
613 | } | |
58687acb DZ |
614 | } |
615 | ||
58687acb | 616 | /* |
586692a5 | 617 | * proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh |
58687acb DZ |
618 | */ |
619 | ||
586692a5 MSB |
620 | int proc_dowatchdog(struct ctl_table *table, int write, |
621 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
58687acb | 622 | { |
e04ab2bc | 623 | int ret; |
58687acb | 624 | |
bcd951cf TG |
625 | if (watchdog_disabled < 0) |
626 | return -ENODEV; | |
627 | ||
586692a5 | 628 | ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
e04ab2bc | 629 | if (ret || !write) |
bcd951cf | 630 | return ret; |
e04ab2bc | 631 | |
0f34c400 | 632 | set_sample_period(); |
b66a2356 | 633 | /* |
634 | * Watchdog threads shouldn't be enabled if they are | |
635 | * disabled. The 'watchdog_disabled' variable check in | |
636 | * watchdog_*_all_cpus() function takes care of this. | |
637 | */ | |
586692a5 | 638 | if (watchdog_enabled && watchdog_thresh) |
e04ab2bc MSB |
639 | watchdog_enable_all_cpus(); |
640 | else | |
641 | watchdog_disable_all_cpus(); | |
642 | ||
e04ab2bc | 643 | return ret; |
58687acb | 644 | } |
58687acb DZ |
645 | #endif /* CONFIG_SYSCTL */ |
646 | ||
bcd951cf TG |
647 | static struct smp_hotplug_thread watchdog_threads = { |
648 | .store = &softlockup_watchdog, | |
649 | .thread_should_run = watchdog_should_run, | |
650 | .thread_fn = watchdog, | |
651 | .thread_comm = "watchdog/%u", | |
652 | .setup = watchdog_enable, | |
653 | .park = watchdog_disable, | |
654 | .unpark = watchdog_enable, | |
58687acb DZ |
655 | }; |
656 | ||
004417a6 | 657 | void __init lockup_detector_init(void) |
58687acb | 658 | { |
0f34c400 | 659 | set_sample_period(); |
bcd951cf TG |
660 | if (smpboot_register_percpu_thread(&watchdog_threads)) { |
661 | pr_err("Failed to create watchdog threads, disabled\n"); | |
662 | watchdog_disabled = -ENODEV; | |
663 | } | |
58687acb | 664 | } |