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); | |
b1a8de1f | 50 | static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved); |
23637d47 | 51 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
cafcd80d DZ |
52 | static DEFINE_PER_CPU(bool, hard_watchdog_warn); |
53 | static DEFINE_PER_CPU(bool, watchdog_nmi_touch); | |
58687acb DZ |
54 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); |
55 | static DEFINE_PER_CPU(struct perf_event *, watchdog_ev); | |
56 | #endif | |
ed235875 | 57 | static unsigned long soft_lockup_nmi_warn; |
58687acb | 58 | |
58687acb DZ |
59 | /* boot commands */ |
60 | /* | |
61 | * Should we panic when a soft-lockup or hard-lockup occurs: | |
62 | */ | |
23637d47 | 63 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
fef2c9bc DZ |
64 | static int hardlockup_panic = |
65 | CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE; | |
58687acb DZ |
66 | |
67 | static int __init hardlockup_panic_setup(char *str) | |
68 | { | |
69 | if (!strncmp(str, "panic", 5)) | |
70 | hardlockup_panic = 1; | |
fef2c9bc DZ |
71 | else if (!strncmp(str, "nopanic", 7)) |
72 | hardlockup_panic = 0; | |
5dc30558 | 73 | else if (!strncmp(str, "0", 1)) |
3c00ea82 | 74 | watchdog_user_enabled = 0; |
58687acb DZ |
75 | return 1; |
76 | } | |
77 | __setup("nmi_watchdog=", hardlockup_panic_setup); | |
78 | #endif | |
79 | ||
80 | unsigned int __read_mostly softlockup_panic = | |
81 | CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE; | |
82 | ||
83 | static int __init softlockup_panic_setup(char *str) | |
84 | { | |
85 | softlockup_panic = simple_strtoul(str, NULL, 0); | |
86 | ||
87 | return 1; | |
88 | } | |
89 | __setup("softlockup_panic=", softlockup_panic_setup); | |
90 | ||
91 | static int __init nowatchdog_setup(char *str) | |
92 | { | |
3c00ea82 | 93 | watchdog_user_enabled = 0; |
58687acb DZ |
94 | return 1; |
95 | } | |
96 | __setup("nowatchdog", nowatchdog_setup); | |
97 | ||
98 | /* deprecated */ | |
99 | static int __init nosoftlockup_setup(char *str) | |
100 | { | |
3c00ea82 | 101 | watchdog_user_enabled = 0; |
58687acb DZ |
102 | return 1; |
103 | } | |
104 | __setup("nosoftlockup", nosoftlockup_setup); | |
105 | /* */ | |
ed235875 AT |
106 | #ifdef CONFIG_SMP |
107 | static int __init softlockup_all_cpu_backtrace_setup(char *str) | |
108 | { | |
109 | sysctl_softlockup_all_cpu_backtrace = | |
110 | !!simple_strtol(str, NULL, 0); | |
111 | return 1; | |
112 | } | |
113 | __setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup); | |
114 | #endif | |
58687acb | 115 | |
4eec42f3 MSB |
116 | /* |
117 | * Hard-lockup warnings should be triggered after just a few seconds. Soft- | |
118 | * lockups can have false positives under extreme conditions. So we generally | |
119 | * want a higher threshold for soft lockups than for hard lockups. So we couple | |
120 | * the thresholds with a factor: we make the soft threshold twice the amount of | |
121 | * time the hard threshold is. | |
122 | */ | |
6e9101ae | 123 | static int get_softlockup_thresh(void) |
4eec42f3 MSB |
124 | { |
125 | return watchdog_thresh * 2; | |
126 | } | |
58687acb DZ |
127 | |
128 | /* | |
129 | * Returns seconds, approximately. We don't need nanosecond | |
130 | * resolution, and we don't need to waste time with a big divide when | |
131 | * 2^30ns == 1.074s. | |
132 | */ | |
c06b4f19 | 133 | static unsigned long get_timestamp(void) |
58687acb | 134 | { |
c06b4f19 | 135 | return local_clock() >> 30LL; /* 2^30 ~= 10^9 */ |
58687acb DZ |
136 | } |
137 | ||
0f34c400 | 138 | static void set_sample_period(void) |
58687acb DZ |
139 | { |
140 | /* | |
586692a5 | 141 | * convert watchdog_thresh from seconds to ns |
86f5e6a7 FLVC |
142 | * the divide by 5 is to give hrtimer several chances (two |
143 | * or three with the current relation between the soft | |
144 | * and hard thresholds) to increment before the | |
145 | * hardlockup detector generates a warning | |
58687acb | 146 | */ |
0f34c400 | 147 | sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); |
58687acb DZ |
148 | } |
149 | ||
150 | /* Commands for resetting the watchdog */ | |
151 | static void __touch_watchdog(void) | |
152 | { | |
c06b4f19 | 153 | __this_cpu_write(watchdog_touch_ts, get_timestamp()); |
58687acb DZ |
154 | } |
155 | ||
332fbdbc | 156 | void touch_softlockup_watchdog(void) |
58687acb | 157 | { |
7861144b AM |
158 | /* |
159 | * Preemption can be enabled. It doesn't matter which CPU's timestamp | |
160 | * gets zeroed here, so use the raw_ operation. | |
161 | */ | |
162 | raw_cpu_write(watchdog_touch_ts, 0); | |
58687acb | 163 | } |
0167c781 | 164 | EXPORT_SYMBOL(touch_softlockup_watchdog); |
58687acb | 165 | |
332fbdbc | 166 | void touch_all_softlockup_watchdogs(void) |
58687acb DZ |
167 | { |
168 | int cpu; | |
169 | ||
170 | /* | |
171 | * this is done lockless | |
172 | * do we care if a 0 races with a timestamp? | |
173 | * all it means is the softlock check starts one cycle later | |
174 | */ | |
175 | for_each_online_cpu(cpu) | |
176 | per_cpu(watchdog_touch_ts, cpu) = 0; | |
177 | } | |
178 | ||
cafcd80d | 179 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb DZ |
180 | void touch_nmi_watchdog(void) |
181 | { | |
62572e29 BZ |
182 | /* |
183 | * Using __raw here because some code paths have | |
184 | * preemption enabled. If preemption is enabled | |
185 | * then interrupts should be enabled too, in which | |
186 | * case we shouldn't have to worry about the watchdog | |
187 | * going off. | |
188 | */ | |
189 | __raw_get_cpu_var(watchdog_nmi_touch) = true; | |
332fbdbc | 190 | touch_softlockup_watchdog(); |
58687acb DZ |
191 | } |
192 | EXPORT_SYMBOL(touch_nmi_watchdog); | |
193 | ||
cafcd80d DZ |
194 | #endif |
195 | ||
58687acb DZ |
196 | void touch_softlockup_watchdog_sync(void) |
197 | { | |
198 | __raw_get_cpu_var(softlockup_touch_sync) = true; | |
199 | __raw_get_cpu_var(watchdog_touch_ts) = 0; | |
200 | } | |
201 | ||
23637d47 | 202 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb | 203 | /* watchdog detector functions */ |
26e09c6e | 204 | static int is_hardlockup(void) |
58687acb | 205 | { |
909ea964 | 206 | unsigned long hrint = __this_cpu_read(hrtimer_interrupts); |
58687acb | 207 | |
909ea964 | 208 | if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) |
58687acb DZ |
209 | return 1; |
210 | ||
909ea964 | 211 | __this_cpu_write(hrtimer_interrupts_saved, hrint); |
58687acb DZ |
212 | return 0; |
213 | } | |
214 | #endif | |
215 | ||
26e09c6e | 216 | static int is_softlockup(unsigned long touch_ts) |
58687acb | 217 | { |
c06b4f19 | 218 | unsigned long now = get_timestamp(); |
58687acb DZ |
219 | |
220 | /* Warn about unreasonable delays: */ | |
4eec42f3 | 221 | if (time_after(now, touch_ts + get_softlockup_thresh())) |
58687acb DZ |
222 | return now - touch_ts; |
223 | ||
224 | return 0; | |
225 | } | |
226 | ||
23637d47 | 227 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
1880c4ae | 228 | |
58687acb DZ |
229 | static struct perf_event_attr wd_hw_attr = { |
230 | .type = PERF_TYPE_HARDWARE, | |
231 | .config = PERF_COUNT_HW_CPU_CYCLES, | |
232 | .size = sizeof(struct perf_event_attr), | |
233 | .pinned = 1, | |
234 | .disabled = 1, | |
235 | }; | |
236 | ||
237 | /* Callback function for perf event subsystem */ | |
a8b0ca17 | 238 | static void watchdog_overflow_callback(struct perf_event *event, |
58687acb DZ |
239 | struct perf_sample_data *data, |
240 | struct pt_regs *regs) | |
241 | { | |
c6db67cd PZ |
242 | /* Ensure the watchdog never gets throttled */ |
243 | event->hw.interrupts = 0; | |
244 | ||
909ea964 CL |
245 | if (__this_cpu_read(watchdog_nmi_touch) == true) { |
246 | __this_cpu_write(watchdog_nmi_touch, false); | |
58687acb DZ |
247 | return; |
248 | } | |
249 | ||
250 | /* check for a hardlockup | |
251 | * This is done by making sure our timer interrupt | |
252 | * is incrementing. The timer interrupt should have | |
253 | * fired multiple times before we overflow'd. If it hasn't | |
254 | * then this is a good indication the cpu is stuck | |
255 | */ | |
26e09c6e DZ |
256 | if (is_hardlockup()) { |
257 | int this_cpu = smp_processor_id(); | |
258 | ||
58687acb | 259 | /* only print hardlockups once */ |
909ea964 | 260 | if (__this_cpu_read(hard_watchdog_warn) == true) |
58687acb DZ |
261 | return; |
262 | ||
263 | if (hardlockup_panic) | |
656c3b79 FF |
264 | panic("Watchdog detected hard LOCKUP on cpu %d", |
265 | this_cpu); | |
58687acb | 266 | else |
656c3b79 FF |
267 | WARN(1, "Watchdog detected hard LOCKUP on cpu %d", |
268 | this_cpu); | |
58687acb | 269 | |
909ea964 | 270 | __this_cpu_write(hard_watchdog_warn, true); |
58687acb DZ |
271 | return; |
272 | } | |
273 | ||
909ea964 | 274 | __this_cpu_write(hard_watchdog_warn, false); |
58687acb DZ |
275 | return; |
276 | } | |
bcd951cf TG |
277 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
278 | ||
58687acb DZ |
279 | static void watchdog_interrupt_count(void) |
280 | { | |
909ea964 | 281 | __this_cpu_inc(hrtimer_interrupts); |
58687acb | 282 | } |
bcd951cf TG |
283 | |
284 | static int watchdog_nmi_enable(unsigned int cpu); | |
285 | static void watchdog_nmi_disable(unsigned int cpu); | |
58687acb DZ |
286 | |
287 | /* watchdog kicker functions */ | |
288 | static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) | |
289 | { | |
909ea964 | 290 | unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts); |
58687acb DZ |
291 | struct pt_regs *regs = get_irq_regs(); |
292 | int duration; | |
ed235875 | 293 | int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; |
58687acb DZ |
294 | |
295 | /* kick the hardlockup detector */ | |
296 | watchdog_interrupt_count(); | |
297 | ||
298 | /* kick the softlockup detector */ | |
909ea964 | 299 | wake_up_process(__this_cpu_read(softlockup_watchdog)); |
58687acb DZ |
300 | |
301 | /* .. and repeat */ | |
0f34c400 | 302 | hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period)); |
58687acb DZ |
303 | |
304 | if (touch_ts == 0) { | |
909ea964 | 305 | if (unlikely(__this_cpu_read(softlockup_touch_sync))) { |
58687acb DZ |
306 | /* |
307 | * If the time stamp was touched atomically | |
308 | * make sure the scheduler tick is up to date. | |
309 | */ | |
909ea964 | 310 | __this_cpu_write(softlockup_touch_sync, false); |
58687acb DZ |
311 | sched_clock_tick(); |
312 | } | |
5d1c0f4a EM |
313 | |
314 | /* Clear the guest paused flag on watchdog reset */ | |
315 | kvm_check_and_clear_guest_paused(); | |
58687acb DZ |
316 | __touch_watchdog(); |
317 | return HRTIMER_RESTART; | |
318 | } | |
319 | ||
320 | /* check for a softlockup | |
321 | * This is done by making sure a high priority task is | |
322 | * being scheduled. The task touches the watchdog to | |
323 | * indicate it is getting cpu time. If it hasn't then | |
324 | * this is a good indication some task is hogging the cpu | |
325 | */ | |
26e09c6e | 326 | duration = is_softlockup(touch_ts); |
58687acb | 327 | if (unlikely(duration)) { |
5d1c0f4a EM |
328 | /* |
329 | * If a virtual machine is stopped by the host it can look to | |
330 | * the watchdog like a soft lockup, check to see if the host | |
331 | * stopped the vm before we issue the warning | |
332 | */ | |
333 | if (kvm_check_and_clear_guest_paused()) | |
334 | return HRTIMER_RESTART; | |
335 | ||
58687acb | 336 | /* only warn once */ |
b1a8de1f | 337 | if (__this_cpu_read(soft_watchdog_warn) == true) { |
338 | /* | |
339 | * When multiple processes are causing softlockups the | |
340 | * softlockup detector only warns on the first one | |
341 | * because the code relies on a full quiet cycle to | |
342 | * re-arm. The second process prevents the quiet cycle | |
343 | * and never gets reported. Use task pointers to detect | |
344 | * this. | |
345 | */ | |
346 | if (__this_cpu_read(softlockup_task_ptr_saved) != | |
347 | current) { | |
348 | __this_cpu_write(soft_watchdog_warn, false); | |
349 | __touch_watchdog(); | |
350 | } | |
58687acb | 351 | return HRTIMER_RESTART; |
b1a8de1f | 352 | } |
58687acb | 353 | |
ed235875 AT |
354 | if (softlockup_all_cpu_backtrace) { |
355 | /* Prevent multiple soft-lockup reports if one cpu is already | |
356 | * engaged in dumping cpu back traces | |
357 | */ | |
358 | if (test_and_set_bit(0, &soft_lockup_nmi_warn)) { | |
359 | /* Someone else will report us. Let's give up */ | |
360 | __this_cpu_write(soft_watchdog_warn, true); | |
361 | return HRTIMER_RESTART; | |
362 | } | |
363 | } | |
364 | ||
656c3b79 | 365 | pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", |
26e09c6e | 366 | smp_processor_id(), duration, |
58687acb | 367 | current->comm, task_pid_nr(current)); |
b1a8de1f | 368 | __this_cpu_write(softlockup_task_ptr_saved, current); |
58687acb DZ |
369 | print_modules(); |
370 | print_irqtrace_events(current); | |
371 | if (regs) | |
372 | show_regs(regs); | |
373 | else | |
374 | dump_stack(); | |
375 | ||
ed235875 AT |
376 | if (softlockup_all_cpu_backtrace) { |
377 | /* Avoid generating two back traces for current | |
378 | * given that one is already made above | |
379 | */ | |
380 | trigger_allbutself_cpu_backtrace(); | |
381 | ||
382 | clear_bit(0, &soft_lockup_nmi_warn); | |
383 | /* Barrier to sync with other cpus */ | |
384 | smp_mb__after_atomic(); | |
385 | } | |
386 | ||
69361eef | 387 | add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK); |
58687acb DZ |
388 | if (softlockup_panic) |
389 | panic("softlockup: hung tasks"); | |
909ea964 | 390 | __this_cpu_write(soft_watchdog_warn, true); |
58687acb | 391 | } else |
909ea964 | 392 | __this_cpu_write(soft_watchdog_warn, false); |
58687acb DZ |
393 | |
394 | return HRTIMER_RESTART; | |
395 | } | |
396 | ||
bcd951cf TG |
397 | static void watchdog_set_prio(unsigned int policy, unsigned int prio) |
398 | { | |
399 | struct sched_param param = { .sched_priority = prio }; | |
58687acb | 400 | |
bcd951cf TG |
401 | sched_setscheduler(current, policy, ¶m); |
402 | } | |
403 | ||
404 | static void watchdog_enable(unsigned int cpu) | |
58687acb | 405 | { |
26e09c6e | 406 | struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); |
58687acb | 407 | |
3935e895 BM |
408 | /* kick off the timer for the hardlockup detector */ |
409 | hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
410 | hrtimer->function = watchdog_timer_fn; | |
411 | ||
bcd951cf TG |
412 | /* Enable the perf event */ |
413 | watchdog_nmi_enable(cpu); | |
58687acb | 414 | |
58687acb | 415 | /* done here because hrtimer_start can only pin to smp_processor_id() */ |
0f34c400 | 416 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
58687acb DZ |
417 | HRTIMER_MODE_REL_PINNED); |
418 | ||
bcd951cf TG |
419 | /* initialize timestamp */ |
420 | watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1); | |
421 | __touch_watchdog(); | |
422 | } | |
58687acb | 423 | |
bcd951cf TG |
424 | static void watchdog_disable(unsigned int cpu) |
425 | { | |
426 | struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); | |
58687acb | 427 | |
bcd951cf TG |
428 | watchdog_set_prio(SCHED_NORMAL, 0); |
429 | hrtimer_cancel(hrtimer); | |
430 | /* disable the perf event */ | |
431 | watchdog_nmi_disable(cpu); | |
58687acb DZ |
432 | } |
433 | ||
b8900bc0 FW |
434 | static void watchdog_cleanup(unsigned int cpu, bool online) |
435 | { | |
436 | watchdog_disable(cpu); | |
437 | } | |
438 | ||
bcd951cf TG |
439 | static int watchdog_should_run(unsigned int cpu) |
440 | { | |
441 | return __this_cpu_read(hrtimer_interrupts) != | |
442 | __this_cpu_read(soft_lockup_hrtimer_cnt); | |
443 | } | |
444 | ||
445 | /* | |
446 | * The watchdog thread function - touches the timestamp. | |
447 | * | |
0f34c400 | 448 | * It only runs once every sample_period seconds (4 seconds by |
bcd951cf TG |
449 | * default) to reset the softlockup timestamp. If this gets delayed |
450 | * for more than 2*watchdog_thresh seconds then the debug-printout | |
451 | * triggers in watchdog_timer_fn(). | |
452 | */ | |
453 | static void watchdog(unsigned int cpu) | |
454 | { | |
455 | __this_cpu_write(soft_lockup_hrtimer_cnt, | |
456 | __this_cpu_read(hrtimer_interrupts)); | |
457 | __touch_watchdog(); | |
458 | } | |
58687acb | 459 | |
23637d47 | 460 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
a7027046 DZ |
461 | /* |
462 | * People like the simple clean cpu node info on boot. | |
463 | * Reduce the watchdog noise by only printing messages | |
464 | * that are different from what cpu0 displayed. | |
465 | */ | |
466 | static unsigned long cpu0_err; | |
467 | ||
bcd951cf | 468 | static int watchdog_nmi_enable(unsigned int cpu) |
58687acb DZ |
469 | { |
470 | struct perf_event_attr *wd_attr; | |
471 | struct perf_event *event = per_cpu(watchdog_ev, cpu); | |
472 | ||
473 | /* is it already setup and enabled? */ | |
474 | if (event && event->state > PERF_EVENT_STATE_OFF) | |
475 | goto out; | |
476 | ||
477 | /* it is setup but not enabled */ | |
478 | if (event != NULL) | |
479 | goto out_enable; | |
480 | ||
58687acb | 481 | wd_attr = &wd_hw_attr; |
4eec42f3 | 482 | wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); |
1880c4ae CG |
483 | |
484 | /* Try to register using hardware perf events */ | |
4dc0da86 | 485 | event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL); |
a7027046 DZ |
486 | |
487 | /* save cpu0 error for future comparision */ | |
488 | if (cpu == 0 && IS_ERR(event)) | |
489 | cpu0_err = PTR_ERR(event); | |
490 | ||
58687acb | 491 | if (!IS_ERR(event)) { |
a7027046 DZ |
492 | /* only print for cpu0 or different than cpu0 */ |
493 | if (cpu == 0 || cpu0_err) | |
494 | pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n"); | |
58687acb DZ |
495 | goto out_save; |
496 | } | |
497 | ||
a7027046 DZ |
498 | /* skip displaying the same error again */ |
499 | if (cpu > 0 && (PTR_ERR(event) == cpu0_err)) | |
500 | return PTR_ERR(event); | |
5651f7f4 DZ |
501 | |
502 | /* vary the KERN level based on the returned errno */ | |
503 | if (PTR_ERR(event) == -EOPNOTSUPP) | |
4501980a | 504 | pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu); |
5651f7f4 | 505 | else if (PTR_ERR(event) == -ENOENT) |
656c3b79 | 506 | pr_warn("disabled (cpu%i): hardware events not enabled\n", |
4501980a | 507 | cpu); |
5651f7f4 | 508 | else |
4501980a AM |
509 | pr_err("disabled (cpu%i): unable to create perf event: %ld\n", |
510 | cpu, PTR_ERR(event)); | |
eac24335 | 511 | return PTR_ERR(event); |
58687acb DZ |
512 | |
513 | /* success path */ | |
514 | out_save: | |
515 | per_cpu(watchdog_ev, cpu) = event; | |
516 | out_enable: | |
517 | perf_event_enable(per_cpu(watchdog_ev, cpu)); | |
518 | out: | |
519 | return 0; | |
520 | } | |
521 | ||
bcd951cf | 522 | static void watchdog_nmi_disable(unsigned int cpu) |
58687acb DZ |
523 | { |
524 | struct perf_event *event = per_cpu(watchdog_ev, cpu); | |
525 | ||
526 | if (event) { | |
527 | perf_event_disable(event); | |
528 | per_cpu(watchdog_ev, cpu) = NULL; | |
529 | ||
530 | /* should be in cleanup, but blocks oprofile */ | |
531 | perf_event_release_kernel(event); | |
532 | } | |
533 | return; | |
534 | } | |
535 | #else | |
bcd951cf TG |
536 | static int watchdog_nmi_enable(unsigned int cpu) { return 0; } |
537 | static void watchdog_nmi_disable(unsigned int cpu) { return; } | |
23637d47 | 538 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
58687acb | 539 | |
b8900bc0 FW |
540 | static struct smp_hotplug_thread watchdog_threads = { |
541 | .store = &softlockup_watchdog, | |
542 | .thread_should_run = watchdog_should_run, | |
543 | .thread_fn = watchdog, | |
544 | .thread_comm = "watchdog/%u", | |
545 | .setup = watchdog_enable, | |
546 | .cleanup = watchdog_cleanup, | |
547 | .park = watchdog_disable, | |
548 | .unpark = watchdog_enable, | |
549 | }; | |
550 | ||
9809b18f MH |
551 | static void restart_watchdog_hrtimer(void *info) |
552 | { | |
553 | struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer); | |
554 | int ret; | |
555 | ||
556 | /* | |
557 | * No need to cancel and restart hrtimer if it is currently executing | |
558 | * because it will reprogram itself with the new period now. | |
559 | * We should never see it unqueued here because we are running per-cpu | |
560 | * with interrupts disabled. | |
561 | */ | |
562 | ret = hrtimer_try_to_cancel(hrtimer); | |
563 | if (ret == 1) | |
564 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), | |
565 | HRTIMER_MODE_REL_PINNED); | |
566 | } | |
567 | ||
568 | static void update_timers(int cpu) | |
569 | { | |
9809b18f MH |
570 | /* |
571 | * Make sure that perf event counter will adopt to a new | |
572 | * sampling period. Updating the sampling period directly would | |
573 | * be much nicer but we do not have an API for that now so | |
574 | * let's use a big hammer. | |
575 | * Hrtimer will adopt the new period on the next tick but this | |
576 | * might be late already so we have to restart the timer as well. | |
577 | */ | |
578 | watchdog_nmi_disable(cpu); | |
e0a23b06 | 579 | smp_call_function_single(cpu, restart_watchdog_hrtimer, NULL, 1); |
9809b18f MH |
580 | watchdog_nmi_enable(cpu); |
581 | } | |
582 | ||
583 | static void update_timers_all_cpus(void) | |
584 | { | |
585 | int cpu; | |
586 | ||
587 | get_online_cpus(); | |
9809b18f MH |
588 | for_each_online_cpu(cpu) |
589 | update_timers(cpu); | |
9809b18f MH |
590 | put_online_cpus(); |
591 | } | |
592 | ||
593 | static int watchdog_enable_all_cpus(bool sample_period_changed) | |
58687acb | 594 | { |
b8900bc0 | 595 | int err = 0; |
58687acb | 596 | |
3c00ea82 | 597 | if (!watchdog_running) { |
b8900bc0 FW |
598 | err = smpboot_register_percpu_thread(&watchdog_threads); |
599 | if (err) | |
600 | pr_err("Failed to create watchdog threads, disabled\n"); | |
601 | else | |
3c00ea82 | 602 | watchdog_running = 1; |
9809b18f MH |
603 | } else if (sample_period_changed) { |
604 | update_timers_all_cpus(); | |
bcd951cf | 605 | } |
b8900bc0 FW |
606 | |
607 | return err; | |
58687acb DZ |
608 | } |
609 | ||
b8900bc0 FW |
610 | /* prepare/enable/disable routines */ |
611 | /* sysctl functions */ | |
612 | #ifdef CONFIG_SYSCTL | |
58687acb DZ |
613 | static void watchdog_disable_all_cpus(void) |
614 | { | |
3c00ea82 FW |
615 | if (watchdog_running) { |
616 | watchdog_running = 0; | |
b8900bc0 | 617 | smpboot_unregister_percpu_thread(&watchdog_threads); |
bcd951cf | 618 | } |
58687acb DZ |
619 | } |
620 | ||
58687acb | 621 | /* |
586692a5 | 622 | * proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh |
58687acb DZ |
623 | */ |
624 | ||
586692a5 MSB |
625 | int proc_dowatchdog(struct ctl_table *table, int write, |
626 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
58687acb | 627 | { |
b8900bc0 | 628 | int err, old_thresh, old_enabled; |
359e6fab | 629 | static DEFINE_MUTEX(watchdog_proc_mutex); |
58687acb | 630 | |
359e6fab | 631 | mutex_lock(&watchdog_proc_mutex); |
b8900bc0 | 632 | old_thresh = ACCESS_ONCE(watchdog_thresh); |
3c00ea82 | 633 | old_enabled = ACCESS_ONCE(watchdog_user_enabled); |
bcd951cf | 634 | |
b8900bc0 FW |
635 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
636 | if (err || !write) | |
359e6fab | 637 | goto out; |
e04ab2bc | 638 | |
0f34c400 | 639 | set_sample_period(); |
b66a2356 | 640 | /* |
641 | * Watchdog threads shouldn't be enabled if they are | |
3c00ea82 | 642 | * disabled. The 'watchdog_running' variable check in |
b66a2356 | 643 | * watchdog_*_all_cpus() function takes care of this. |
644 | */ | |
3c00ea82 | 645 | if (watchdog_user_enabled && watchdog_thresh) |
9809b18f | 646 | err = watchdog_enable_all_cpus(old_thresh != watchdog_thresh); |
e04ab2bc MSB |
647 | else |
648 | watchdog_disable_all_cpus(); | |
649 | ||
b8900bc0 FW |
650 | /* Restore old values on failure */ |
651 | if (err) { | |
652 | watchdog_thresh = old_thresh; | |
3c00ea82 | 653 | watchdog_user_enabled = old_enabled; |
b8900bc0 | 654 | } |
359e6fab MH |
655 | out: |
656 | mutex_unlock(&watchdog_proc_mutex); | |
b8900bc0 | 657 | return err; |
58687acb | 658 | } |
58687acb DZ |
659 | #endif /* CONFIG_SYSCTL */ |
660 | ||
004417a6 | 661 | void __init lockup_detector_init(void) |
58687acb | 662 | { |
0f34c400 | 663 | set_sample_period(); |
b8900bc0 | 664 | |
3c00ea82 | 665 | if (watchdog_user_enabled) |
9809b18f | 666 | watchdog_enable_all_cpus(false); |
58687acb | 667 | } |