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 | ||
3c00ea82 | 32 | int watchdog_user_enabled = 1; |
4eec42f3 | 33 | int __read_mostly watchdog_thresh = 10; |
ed235875 AT |
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 | ||
3c00ea82 | 40 | static int __read_mostly watchdog_running; |
0f34c400 | 41 | static u64 __read_mostly sample_period; |
58687acb DZ |
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); | |
58687acb | 47 | static DEFINE_PER_CPU(bool, soft_watchdog_warn); |
bcd951cf TG |
48 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); |
49 | static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt); | |
23637d47 | 50 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
cafcd80d DZ |
51 | static DEFINE_PER_CPU(bool, hard_watchdog_warn); |
52 | static DEFINE_PER_CPU(bool, watchdog_nmi_touch); | |
58687acb DZ |
53 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); |
54 | static DEFINE_PER_CPU(struct perf_event *, watchdog_ev); | |
55 | #endif | |
ed235875 | 56 | static unsigned long soft_lockup_nmi_warn; |
58687acb | 57 | |
58687acb DZ |
58 | /* boot commands */ |
59 | /* | |
60 | * Should we panic when a soft-lockup or hard-lockup occurs: | |
61 | */ | |
23637d47 | 62 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
fef2c9bc DZ |
63 | static int hardlockup_panic = |
64 | CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE; | |
58687acb DZ |
65 | |
66 | static int __init hardlockup_panic_setup(char *str) | |
67 | { | |
68 | if (!strncmp(str, "panic", 5)) | |
69 | hardlockup_panic = 1; | |
fef2c9bc DZ |
70 | else if (!strncmp(str, "nopanic", 7)) |
71 | hardlockup_panic = 0; | |
5dc30558 | 72 | else if (!strncmp(str, "0", 1)) |
3c00ea82 | 73 | watchdog_user_enabled = 0; |
58687acb DZ |
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 | { | |
3c00ea82 | 92 | watchdog_user_enabled = 0; |
58687acb DZ |
93 | return 1; |
94 | } | |
95 | __setup("nowatchdog", nowatchdog_setup); | |
96 | ||
97 | /* deprecated */ | |
98 | static int __init nosoftlockup_setup(char *str) | |
99 | { | |
3c00ea82 | 100 | watchdog_user_enabled = 0; |
58687acb DZ |
101 | return 1; |
102 | } | |
103 | __setup("nosoftlockup", nosoftlockup_setup); | |
104 | /* */ | |
ed235875 AT |
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 | |
58687acb | 114 | |
4eec42f3 MSB |
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 | */ | |
6e9101ae | 122 | static int get_softlockup_thresh(void) |
4eec42f3 MSB |
123 | { |
124 | return watchdog_thresh * 2; | |
125 | } | |
58687acb DZ |
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 | */ | |
c06b4f19 | 132 | static unsigned long get_timestamp(void) |
58687acb | 133 | { |
c06b4f19 | 134 | return local_clock() >> 30LL; /* 2^30 ~= 10^9 */ |
58687acb DZ |
135 | } |
136 | ||
0f34c400 | 137 | static void set_sample_period(void) |
58687acb DZ |
138 | { |
139 | /* | |
586692a5 | 140 | * convert watchdog_thresh from seconds to ns |
86f5e6a7 FLVC |
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 | |
58687acb | 145 | */ |
0f34c400 | 146 | sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); |
58687acb DZ |
147 | } |
148 | ||
149 | /* Commands for resetting the watchdog */ | |
150 | static void __touch_watchdog(void) | |
151 | { | |
c06b4f19 | 152 | __this_cpu_write(watchdog_touch_ts, get_timestamp()); |
58687acb DZ |
153 | } |
154 | ||
332fbdbc | 155 | void touch_softlockup_watchdog(void) |
58687acb | 156 | { |
7861144b AM |
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); | |
58687acb | 162 | } |
0167c781 | 163 | EXPORT_SYMBOL(touch_softlockup_watchdog); |
58687acb | 164 | |
332fbdbc | 165 | void touch_all_softlockup_watchdogs(void) |
58687acb DZ |
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 | ||
cafcd80d | 178 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb DZ |
179 | void touch_nmi_watchdog(void) |
180 | { | |
62572e29 BZ |
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; | |
332fbdbc | 189 | touch_softlockup_watchdog(); |
58687acb DZ |
190 | } |
191 | EXPORT_SYMBOL(touch_nmi_watchdog); | |
192 | ||
cafcd80d DZ |
193 | #endif |
194 | ||
58687acb DZ |
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 | ||
23637d47 | 201 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb | 202 | /* watchdog detector functions */ |
26e09c6e | 203 | static int is_hardlockup(void) |
58687acb | 204 | { |
909ea964 | 205 | unsigned long hrint = __this_cpu_read(hrtimer_interrupts); |
58687acb | 206 | |
909ea964 | 207 | if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) |
58687acb DZ |
208 | return 1; |
209 | ||
909ea964 | 210 | __this_cpu_write(hrtimer_interrupts_saved, hrint); |
58687acb DZ |
211 | return 0; |
212 | } | |
213 | #endif | |
214 | ||
26e09c6e | 215 | static int is_softlockup(unsigned long touch_ts) |
58687acb | 216 | { |
c06b4f19 | 217 | unsigned long now = get_timestamp(); |
58687acb DZ |
218 | |
219 | /* Warn about unreasonable delays: */ | |
4eec42f3 | 220 | if (time_after(now, touch_ts + get_softlockup_thresh())) |
58687acb DZ |
221 | return now - touch_ts; |
222 | ||
223 | return 0; | |
224 | } | |
225 | ||
23637d47 | 226 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
1880c4ae | 227 | |
58687acb DZ |
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 */ | |
a8b0ca17 | 237 | static void watchdog_overflow_callback(struct perf_event *event, |
58687acb DZ |
238 | struct perf_sample_data *data, |
239 | struct pt_regs *regs) | |
240 | { | |
c6db67cd PZ |
241 | /* Ensure the watchdog never gets throttled */ |
242 | event->hw.interrupts = 0; | |
243 | ||
909ea964 CL |
244 | if (__this_cpu_read(watchdog_nmi_touch) == true) { |
245 | __this_cpu_write(watchdog_nmi_touch, false); | |
58687acb DZ |
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 | */ | |
26e09c6e DZ |
255 | if (is_hardlockup()) { |
256 | int this_cpu = smp_processor_id(); | |
257 | ||
58687acb | 258 | /* only print hardlockups once */ |
909ea964 | 259 | if (__this_cpu_read(hard_watchdog_warn) == true) |
58687acb DZ |
260 | return; |
261 | ||
262 | if (hardlockup_panic) | |
656c3b79 FF |
263 | panic("Watchdog detected hard LOCKUP on cpu %d", |
264 | this_cpu); | |
58687acb | 265 | else |
656c3b79 FF |
266 | WARN(1, "Watchdog detected hard LOCKUP on cpu %d", |
267 | this_cpu); | |
58687acb | 268 | |
909ea964 | 269 | __this_cpu_write(hard_watchdog_warn, true); |
58687acb DZ |
270 | return; |
271 | } | |
272 | ||
909ea964 | 273 | __this_cpu_write(hard_watchdog_warn, false); |
58687acb DZ |
274 | return; |
275 | } | |
bcd951cf TG |
276 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
277 | ||
58687acb DZ |
278 | static void watchdog_interrupt_count(void) |
279 | { | |
909ea964 | 280 | __this_cpu_inc(hrtimer_interrupts); |
58687acb | 281 | } |
bcd951cf TG |
282 | |
283 | static int watchdog_nmi_enable(unsigned int cpu); | |
284 | static void watchdog_nmi_disable(unsigned int cpu); | |
58687acb DZ |
285 | |
286 | /* watchdog kicker functions */ | |
287 | static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) | |
288 | { | |
909ea964 | 289 | unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts); |
58687acb DZ |
290 | struct pt_regs *regs = get_irq_regs(); |
291 | int duration; | |
ed235875 | 292 | int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; |
58687acb DZ |
293 | |
294 | /* kick the hardlockup detector */ | |
295 | watchdog_interrupt_count(); | |
296 | ||
297 | /* kick the softlockup detector */ | |
909ea964 | 298 | wake_up_process(__this_cpu_read(softlockup_watchdog)); |
58687acb DZ |
299 | |
300 | /* .. and repeat */ | |
0f34c400 | 301 | hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period)); |
58687acb DZ |
302 | |
303 | if (touch_ts == 0) { | |
909ea964 | 304 | if (unlikely(__this_cpu_read(softlockup_touch_sync))) { |
58687acb DZ |
305 | /* |
306 | * If the time stamp was touched atomically | |
307 | * make sure the scheduler tick is up to date. | |
308 | */ | |
909ea964 | 309 | __this_cpu_write(softlockup_touch_sync, false); |
58687acb DZ |
310 | sched_clock_tick(); |
311 | } | |
5d1c0f4a EM |
312 | |
313 | /* Clear the guest paused flag on watchdog reset */ | |
314 | kvm_check_and_clear_guest_paused(); | |
58687acb DZ |
315 | __touch_watchdog(); |
316 | return HRTIMER_RESTART; | |
317 | } | |
318 | ||
319 | /* check for a softlockup | |
320 | * This is done by making sure a high priority task is | |
321 | * being scheduled. The task touches the watchdog to | |
322 | * indicate it is getting cpu time. If it hasn't then | |
323 | * this is a good indication some task is hogging the cpu | |
324 | */ | |
26e09c6e | 325 | duration = is_softlockup(touch_ts); |
58687acb | 326 | if (unlikely(duration)) { |
5d1c0f4a EM |
327 | /* |
328 | * If a virtual machine is stopped by the host it can look to | |
329 | * the watchdog like a soft lockup, check to see if the host | |
330 | * stopped the vm before we issue the warning | |
331 | */ | |
332 | if (kvm_check_and_clear_guest_paused()) | |
333 | return HRTIMER_RESTART; | |
334 | ||
58687acb | 335 | /* only warn once */ |
909ea964 | 336 | if (__this_cpu_read(soft_watchdog_warn) == true) |
58687acb DZ |
337 | return HRTIMER_RESTART; |
338 | ||
ed235875 AT |
339 | if (softlockup_all_cpu_backtrace) { |
340 | /* Prevent multiple soft-lockup reports if one cpu is already | |
341 | * engaged in dumping cpu back traces | |
342 | */ | |
343 | if (test_and_set_bit(0, &soft_lockup_nmi_warn)) { | |
344 | /* Someone else will report us. Let's give up */ | |
345 | __this_cpu_write(soft_watchdog_warn, true); | |
346 | return HRTIMER_RESTART; | |
347 | } | |
348 | } | |
349 | ||
656c3b79 | 350 | pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", |
26e09c6e | 351 | smp_processor_id(), duration, |
58687acb DZ |
352 | current->comm, task_pid_nr(current)); |
353 | print_modules(); | |
354 | print_irqtrace_events(current); | |
355 | if (regs) | |
356 | show_regs(regs); | |
357 | else | |
358 | dump_stack(); | |
359 | ||
ed235875 AT |
360 | if (softlockup_all_cpu_backtrace) { |
361 | /* Avoid generating two back traces for current | |
362 | * given that one is already made above | |
363 | */ | |
364 | trigger_allbutself_cpu_backtrace(); | |
365 | ||
366 | clear_bit(0, &soft_lockup_nmi_warn); | |
367 | /* Barrier to sync with other cpus */ | |
368 | smp_mb__after_atomic(); | |
369 | } | |
370 | ||
58687acb DZ |
371 | if (softlockup_panic) |
372 | panic("softlockup: hung tasks"); | |
909ea964 | 373 | __this_cpu_write(soft_watchdog_warn, true); |
58687acb | 374 | } else |
909ea964 | 375 | __this_cpu_write(soft_watchdog_warn, false); |
58687acb DZ |
376 | |
377 | return HRTIMER_RESTART; | |
378 | } | |
379 | ||
bcd951cf TG |
380 | static void watchdog_set_prio(unsigned int policy, unsigned int prio) |
381 | { | |
382 | struct sched_param param = { .sched_priority = prio }; | |
58687acb | 383 | |
bcd951cf TG |
384 | sched_setscheduler(current, policy, ¶m); |
385 | } | |
386 | ||
387 | static void watchdog_enable(unsigned int cpu) | |
58687acb | 388 | { |
26e09c6e | 389 | struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); |
58687acb | 390 | |
3935e895 BM |
391 | /* kick off the timer for the hardlockup detector */ |
392 | hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
393 | hrtimer->function = watchdog_timer_fn; | |
394 | ||
bcd951cf TG |
395 | /* Enable the perf event */ |
396 | watchdog_nmi_enable(cpu); | |
58687acb | 397 | |
58687acb | 398 | /* done here because hrtimer_start can only pin to smp_processor_id() */ |
0f34c400 | 399 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
58687acb DZ |
400 | HRTIMER_MODE_REL_PINNED); |
401 | ||
bcd951cf TG |
402 | /* initialize timestamp */ |
403 | watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1); | |
404 | __touch_watchdog(); | |
405 | } | |
58687acb | 406 | |
bcd951cf TG |
407 | static void watchdog_disable(unsigned int cpu) |
408 | { | |
409 | struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); | |
58687acb | 410 | |
bcd951cf TG |
411 | watchdog_set_prio(SCHED_NORMAL, 0); |
412 | hrtimer_cancel(hrtimer); | |
413 | /* disable the perf event */ | |
414 | watchdog_nmi_disable(cpu); | |
58687acb DZ |
415 | } |
416 | ||
b8900bc0 FW |
417 | static void watchdog_cleanup(unsigned int cpu, bool online) |
418 | { | |
419 | watchdog_disable(cpu); | |
420 | } | |
421 | ||
bcd951cf TG |
422 | static int watchdog_should_run(unsigned int cpu) |
423 | { | |
424 | return __this_cpu_read(hrtimer_interrupts) != | |
425 | __this_cpu_read(soft_lockup_hrtimer_cnt); | |
426 | } | |
427 | ||
428 | /* | |
429 | * The watchdog thread function - touches the timestamp. | |
430 | * | |
0f34c400 | 431 | * It only runs once every sample_period seconds (4 seconds by |
bcd951cf TG |
432 | * default) to reset the softlockup timestamp. If this gets delayed |
433 | * for more than 2*watchdog_thresh seconds then the debug-printout | |
434 | * triggers in watchdog_timer_fn(). | |
435 | */ | |
436 | static void watchdog(unsigned int cpu) | |
437 | { | |
438 | __this_cpu_write(soft_lockup_hrtimer_cnt, | |
439 | __this_cpu_read(hrtimer_interrupts)); | |
440 | __touch_watchdog(); | |
441 | } | |
58687acb | 442 | |
23637d47 | 443 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
a7027046 DZ |
444 | /* |
445 | * People like the simple clean cpu node info on boot. | |
446 | * Reduce the watchdog noise by only printing messages | |
447 | * that are different from what cpu0 displayed. | |
448 | */ | |
449 | static unsigned long cpu0_err; | |
450 | ||
bcd951cf | 451 | static int watchdog_nmi_enable(unsigned int cpu) |
58687acb DZ |
452 | { |
453 | struct perf_event_attr *wd_attr; | |
454 | struct perf_event *event = per_cpu(watchdog_ev, cpu); | |
455 | ||
456 | /* is it already setup and enabled? */ | |
457 | if (event && event->state > PERF_EVENT_STATE_OFF) | |
458 | goto out; | |
459 | ||
460 | /* it is setup but not enabled */ | |
461 | if (event != NULL) | |
462 | goto out_enable; | |
463 | ||
58687acb | 464 | wd_attr = &wd_hw_attr; |
4eec42f3 | 465 | wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); |
1880c4ae CG |
466 | |
467 | /* Try to register using hardware perf events */ | |
4dc0da86 | 468 | event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL); |
a7027046 DZ |
469 | |
470 | /* save cpu0 error for future comparision */ | |
471 | if (cpu == 0 && IS_ERR(event)) | |
472 | cpu0_err = PTR_ERR(event); | |
473 | ||
58687acb | 474 | if (!IS_ERR(event)) { |
a7027046 DZ |
475 | /* only print for cpu0 or different than cpu0 */ |
476 | if (cpu == 0 || cpu0_err) | |
477 | pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n"); | |
58687acb DZ |
478 | goto out_save; |
479 | } | |
480 | ||
a7027046 DZ |
481 | /* skip displaying the same error again */ |
482 | if (cpu > 0 && (PTR_ERR(event) == cpu0_err)) | |
483 | return PTR_ERR(event); | |
5651f7f4 DZ |
484 | |
485 | /* vary the KERN level based on the returned errno */ | |
486 | if (PTR_ERR(event) == -EOPNOTSUPP) | |
4501980a | 487 | pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu); |
5651f7f4 | 488 | else if (PTR_ERR(event) == -ENOENT) |
656c3b79 | 489 | pr_warn("disabled (cpu%i): hardware events not enabled\n", |
4501980a | 490 | cpu); |
5651f7f4 | 491 | else |
4501980a AM |
492 | pr_err("disabled (cpu%i): unable to create perf event: %ld\n", |
493 | cpu, PTR_ERR(event)); | |
eac24335 | 494 | return PTR_ERR(event); |
58687acb DZ |
495 | |
496 | /* success path */ | |
497 | out_save: | |
498 | per_cpu(watchdog_ev, cpu) = event; | |
499 | out_enable: | |
500 | perf_event_enable(per_cpu(watchdog_ev, cpu)); | |
501 | out: | |
502 | return 0; | |
503 | } | |
504 | ||
bcd951cf | 505 | static void watchdog_nmi_disable(unsigned int cpu) |
58687acb DZ |
506 | { |
507 | struct perf_event *event = per_cpu(watchdog_ev, cpu); | |
508 | ||
509 | if (event) { | |
510 | perf_event_disable(event); | |
511 | per_cpu(watchdog_ev, cpu) = NULL; | |
512 | ||
513 | /* should be in cleanup, but blocks oprofile */ | |
514 | perf_event_release_kernel(event); | |
515 | } | |
516 | return; | |
517 | } | |
518 | #else | |
bcd951cf TG |
519 | static int watchdog_nmi_enable(unsigned int cpu) { return 0; } |
520 | static void watchdog_nmi_disable(unsigned int cpu) { return; } | |
23637d47 | 521 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
58687acb | 522 | |
b8900bc0 FW |
523 | static struct smp_hotplug_thread watchdog_threads = { |
524 | .store = &softlockup_watchdog, | |
525 | .thread_should_run = watchdog_should_run, | |
526 | .thread_fn = watchdog, | |
527 | .thread_comm = "watchdog/%u", | |
528 | .setup = watchdog_enable, | |
529 | .cleanup = watchdog_cleanup, | |
530 | .park = watchdog_disable, | |
531 | .unpark = watchdog_enable, | |
532 | }; | |
533 | ||
9809b18f MH |
534 | static void restart_watchdog_hrtimer(void *info) |
535 | { | |
536 | struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); | |
537 | int ret; | |
538 | ||
539 | /* | |
540 | * No need to cancel and restart hrtimer if it is currently executing | |
541 | * because it will reprogram itself with the new period now. | |
542 | * We should never see it unqueued here because we are running per-cpu | |
543 | * with interrupts disabled. | |
544 | */ | |
545 | ret = hrtimer_try_to_cancel(hrtimer); | |
546 | if (ret == 1) | |
547 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), | |
548 | HRTIMER_MODE_REL_PINNED); | |
549 | } | |
550 | ||
551 | static void update_timers(int cpu) | |
552 | { | |
9809b18f MH |
553 | /* |
554 | * Make sure that perf event counter will adopt to a new | |
555 | * sampling period. Updating the sampling period directly would | |
556 | * be much nicer but we do not have an API for that now so | |
557 | * let's use a big hammer. | |
558 | * Hrtimer will adopt the new period on the next tick but this | |
559 | * might be late already so we have to restart the timer as well. | |
560 | */ | |
561 | watchdog_nmi_disable(cpu); | |
e0a23b06 | 562 | smp_call_function_single(cpu, restart_watchdog_hrtimer, NULL, 1); |
9809b18f MH |
563 | watchdog_nmi_enable(cpu); |
564 | } | |
565 | ||
566 | static void update_timers_all_cpus(void) | |
567 | { | |
568 | int cpu; | |
569 | ||
570 | get_online_cpus(); | |
9809b18f MH |
571 | for_each_online_cpu(cpu) |
572 | update_timers(cpu); | |
9809b18f MH |
573 | put_online_cpus(); |
574 | } | |
575 | ||
576 | static int watchdog_enable_all_cpus(bool sample_period_changed) | |
58687acb | 577 | { |
b8900bc0 | 578 | int err = 0; |
58687acb | 579 | |
3c00ea82 | 580 | if (!watchdog_running) { |
b8900bc0 FW |
581 | err = smpboot_register_percpu_thread(&watchdog_threads); |
582 | if (err) | |
583 | pr_err("Failed to create watchdog threads, disabled\n"); | |
584 | else | |
3c00ea82 | 585 | watchdog_running = 1; |
9809b18f MH |
586 | } else if (sample_period_changed) { |
587 | update_timers_all_cpus(); | |
bcd951cf | 588 | } |
b8900bc0 FW |
589 | |
590 | return err; | |
58687acb DZ |
591 | } |
592 | ||
b8900bc0 FW |
593 | /* prepare/enable/disable routines */ |
594 | /* sysctl functions */ | |
595 | #ifdef CONFIG_SYSCTL | |
58687acb DZ |
596 | static void watchdog_disable_all_cpus(void) |
597 | { | |
3c00ea82 FW |
598 | if (watchdog_running) { |
599 | watchdog_running = 0; | |
b8900bc0 | 600 | smpboot_unregister_percpu_thread(&watchdog_threads); |
bcd951cf | 601 | } |
58687acb DZ |
602 | } |
603 | ||
58687acb | 604 | /* |
586692a5 | 605 | * proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh |
58687acb DZ |
606 | */ |
607 | ||
586692a5 MSB |
608 | int proc_dowatchdog(struct ctl_table *table, int write, |
609 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
58687acb | 610 | { |
b8900bc0 | 611 | int err, old_thresh, old_enabled; |
359e6fab | 612 | static DEFINE_MUTEX(watchdog_proc_mutex); |
58687acb | 613 | |
359e6fab | 614 | mutex_lock(&watchdog_proc_mutex); |
b8900bc0 | 615 | old_thresh = ACCESS_ONCE(watchdog_thresh); |
3c00ea82 | 616 | old_enabled = ACCESS_ONCE(watchdog_user_enabled); |
bcd951cf | 617 | |
b8900bc0 FW |
618 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
619 | if (err || !write) | |
359e6fab | 620 | goto out; |
e04ab2bc | 621 | |
0f34c400 | 622 | set_sample_period(); |
b66a2356 | 623 | /* |
624 | * Watchdog threads shouldn't be enabled if they are | |
3c00ea82 | 625 | * disabled. The 'watchdog_running' variable check in |
b66a2356 | 626 | * watchdog_*_all_cpus() function takes care of this. |
627 | */ | |
3c00ea82 | 628 | if (watchdog_user_enabled && watchdog_thresh) |
9809b18f | 629 | err = watchdog_enable_all_cpus(old_thresh != watchdog_thresh); |
e04ab2bc MSB |
630 | else |
631 | watchdog_disable_all_cpus(); | |
632 | ||
b8900bc0 FW |
633 | /* Restore old values on failure */ |
634 | if (err) { | |
635 | watchdog_thresh = old_thresh; | |
3c00ea82 | 636 | watchdog_user_enabled = old_enabled; |
b8900bc0 | 637 | } |
359e6fab MH |
638 | out: |
639 | mutex_unlock(&watchdog_proc_mutex); | |
b8900bc0 | 640 | return err; |
58687acb | 641 | } |
58687acb DZ |
642 | #endif /* CONFIG_SYSCTL */ |
643 | ||
004417a6 | 644 | void __init lockup_detector_init(void) |
58687acb | 645 | { |
0f34c400 | 646 | set_sample_period(); |
b8900bc0 | 647 | |
3c00ea82 | 648 | if (watchdog_user_enabled) |
9809b18f | 649 | watchdog_enable_all_cpus(false); |
58687acb | 650 | } |