Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
58687acb DZ |
2 | /* |
3 | * Detect hard and soft lockups on a system | |
4 | * | |
5 | * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc. | |
6 | * | |
86f5e6a7 FLVC |
7 | * Note: Most of this code is borrowed heavily from the original softlockup |
8 | * detector, so thanks to Ingo for the initial implementation. | |
9 | * Some chunks also taken from the old x86-specific nmi watchdog code, thanks | |
58687acb DZ |
10 | * to those contributors as well. |
11 | */ | |
12 | ||
5f92a7b0 | 13 | #define pr_fmt(fmt) "watchdog: " fmt |
4501980a | 14 | |
58687acb DZ |
15 | #include <linux/mm.h> |
16 | #include <linux/cpu.h> | |
17 | #include <linux/nmi.h> | |
18 | #include <linux/init.h> | |
58687acb DZ |
19 | #include <linux/module.h> |
20 | #include <linux/sysctl.h> | |
bcd951cf | 21 | #include <linux/smpboot.h> |
8bd75c77 | 22 | #include <linux/sched/rt.h> |
ae7e81c0 | 23 | #include <uapi/linux/sched/types.h> |
fe4ba3c3 | 24 | #include <linux/tick.h> |
82607adc | 25 | #include <linux/workqueue.h> |
e6017571 | 26 | #include <linux/sched/clock.h> |
b17b0153 | 27 | #include <linux/sched/debug.h> |
78634061 | 28 | #include <linux/sched/isolation.h> |
58687acb DZ |
29 | |
30 | #include <asm/irq_regs.h> | |
5d1c0f4a | 31 | #include <linux/kvm_para.h> |
81a4beef | 32 | #include <linux/kthread.h> |
58687acb | 33 | |
946d1977 | 34 | static DEFINE_MUTEX(watchdog_mutex); |
ab992dc3 | 35 | |
05a4a952 | 36 | #if defined(CONFIG_HARDLOCKUP_DETECTOR) || defined(CONFIG_HAVE_NMI_WATCHDOG) |
09154985 TG |
37 | # define WATCHDOG_DEFAULT (SOFT_WATCHDOG_ENABLED | NMI_WATCHDOG_ENABLED) |
38 | # define NMI_WATCHDOG_DEFAULT 1 | |
84d56e66 | 39 | #else |
09154985 TG |
40 | # define WATCHDOG_DEFAULT (SOFT_WATCHDOG_ENABLED) |
41 | # define NMI_WATCHDOG_DEFAULT 0 | |
84d56e66 | 42 | #endif |
05a4a952 | 43 | |
09154985 TG |
44 | unsigned long __read_mostly watchdog_enabled; |
45 | int __read_mostly watchdog_user_enabled = 1; | |
46 | int __read_mostly nmi_watchdog_user_enabled = NMI_WATCHDOG_DEFAULT; | |
47 | int __read_mostly soft_watchdog_user_enabled = 1; | |
7feeb9cd | 48 | int __read_mostly watchdog_thresh = 10; |
a994a314 | 49 | int __read_mostly nmi_watchdog_available; |
7feeb9cd TG |
50 | |
51 | struct cpumask watchdog_allowed_mask __read_mostly; | |
7feeb9cd TG |
52 | |
53 | struct cpumask watchdog_cpumask __read_mostly; | |
54 | unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask); | |
55 | ||
05a4a952 | 56 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
05a4a952 NP |
57 | /* |
58 | * Should we panic when a soft-lockup or hard-lockup occurs: | |
59 | */ | |
60 | unsigned int __read_mostly hardlockup_panic = | |
61 | CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE; | |
62 | /* | |
63 | * We may not want to enable hard lockup detection by default in all cases, | |
64 | * for example when running the kernel as a guest on a hypervisor. In these | |
65 | * cases this function can be called to disable hard lockup detection. This | |
66 | * function should only be executed once by the boot processor before the | |
67 | * kernel command line parameters are parsed, because otherwise it is not | |
68 | * possible to override this in hardlockup_panic_setup(). | |
69 | */ | |
7a355820 | 70 | void __init hardlockup_detector_disable(void) |
05a4a952 | 71 | { |
09154985 | 72 | nmi_watchdog_user_enabled = 0; |
05a4a952 NP |
73 | } |
74 | ||
75 | static int __init hardlockup_panic_setup(char *str) | |
76 | { | |
77 | if (!strncmp(str, "panic", 5)) | |
78 | hardlockup_panic = 1; | |
79 | else if (!strncmp(str, "nopanic", 7)) | |
80 | hardlockup_panic = 0; | |
81 | else if (!strncmp(str, "0", 1)) | |
09154985 | 82 | nmi_watchdog_user_enabled = 0; |
05a4a952 | 83 | else if (!strncmp(str, "1", 1)) |
09154985 | 84 | nmi_watchdog_user_enabled = 1; |
05a4a952 NP |
85 | return 1; |
86 | } | |
87 | __setup("nmi_watchdog=", hardlockup_panic_setup); | |
88 | ||
368a7e2c TG |
89 | # ifdef CONFIG_SMP |
90 | int __read_mostly sysctl_hardlockup_all_cpu_backtrace; | |
05a4a952 | 91 | |
368a7e2c TG |
92 | static int __init hardlockup_all_cpu_backtrace_setup(char *str) |
93 | { | |
94 | sysctl_hardlockup_all_cpu_backtrace = !!simple_strtol(str, NULL, 0); | |
95 | return 1; | |
96 | } | |
97 | __setup("hardlockup_all_cpu_backtrace=", hardlockup_all_cpu_backtrace_setup); | |
98 | # endif /* CONFIG_SMP */ | |
99 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ | |
05a4a952 | 100 | |
05a4a952 NP |
101 | /* |
102 | * These functions can be overridden if an architecture implements its | |
103 | * own hardlockup detector. | |
a10a842f NP |
104 | * |
105 | * watchdog_nmi_enable/disable can be implemented to start and stop when | |
106 | * softlockup watchdog threads start and stop. The arch must select the | |
107 | * SOFTLOCKUP_DETECTOR Kconfig. | |
05a4a952 NP |
108 | */ |
109 | int __weak watchdog_nmi_enable(unsigned int cpu) | |
110 | { | |
146c9d0e | 111 | hardlockup_detector_perf_enable(); |
05a4a952 NP |
112 | return 0; |
113 | } | |
941154bd | 114 | |
05a4a952 NP |
115 | void __weak watchdog_nmi_disable(unsigned int cpu) |
116 | { | |
941154bd | 117 | hardlockup_detector_perf_disable(); |
05a4a952 NP |
118 | } |
119 | ||
a994a314 TG |
120 | /* Return 0, if a NMI watchdog is available. Error code otherwise */ |
121 | int __weak __init watchdog_nmi_probe(void) | |
122 | { | |
123 | return hardlockup_detector_perf_init(); | |
124 | } | |
125 | ||
6592ad2f | 126 | /** |
6b9dc480 | 127 | * watchdog_nmi_stop - Stop the watchdog for reconfiguration |
6592ad2f | 128 | * |
6b9dc480 TG |
129 | * The reconfiguration steps are: |
130 | * watchdog_nmi_stop(); | |
6592ad2f | 131 | * update_variables(); |
6b9dc480 TG |
132 | * watchdog_nmi_start(); |
133 | */ | |
134 | void __weak watchdog_nmi_stop(void) { } | |
135 | ||
136 | /** | |
137 | * watchdog_nmi_start - Start the watchdog after reconfiguration | |
6592ad2f | 138 | * |
6b9dc480 TG |
139 | * Counterpart to watchdog_nmi_stop(). |
140 | * | |
141 | * The following variables have been updated in update_variables() and | |
142 | * contain the currently valid configuration: | |
7feeb9cd | 143 | * - watchdog_enabled |
a10a842f NP |
144 | * - watchdog_thresh |
145 | * - watchdog_cpumask | |
a10a842f | 146 | */ |
6b9dc480 | 147 | void __weak watchdog_nmi_start(void) { } |
a10a842f | 148 | |
09154985 TG |
149 | /** |
150 | * lockup_detector_update_enable - Update the sysctl enable bit | |
151 | * | |
152 | * Caller needs to make sure that the NMI/perf watchdogs are off, so this | |
153 | * can't race with watchdog_nmi_disable(). | |
154 | */ | |
155 | static void lockup_detector_update_enable(void) | |
156 | { | |
157 | watchdog_enabled = 0; | |
158 | if (!watchdog_user_enabled) | |
159 | return; | |
a994a314 | 160 | if (nmi_watchdog_available && nmi_watchdog_user_enabled) |
09154985 TG |
161 | watchdog_enabled |= NMI_WATCHDOG_ENABLED; |
162 | if (soft_watchdog_user_enabled) | |
163 | watchdog_enabled |= SOFT_WATCHDOG_ENABLED; | |
164 | } | |
165 | ||
05a4a952 NP |
166 | #ifdef CONFIG_SOFTLOCKUP_DETECTOR |
167 | ||
2b9d7f23 TG |
168 | /* Global variables, exported for sysctl */ |
169 | unsigned int __read_mostly softlockup_panic = | |
170 | CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE; | |
2eb2527f | 171 | |
0b62bf86 | 172 | static bool softlockup_threads_initialized __read_mostly; |
0f34c400 | 173 | static u64 __read_mostly sample_period; |
58687acb DZ |
174 | |
175 | static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); | |
176 | static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog); | |
177 | static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer); | |
178 | static DEFINE_PER_CPU(bool, softlockup_touch_sync); | |
58687acb | 179 | static DEFINE_PER_CPU(bool, soft_watchdog_warn); |
bcd951cf TG |
180 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); |
181 | static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt); | |
b1a8de1f | 182 | static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved); |
58687acb | 183 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); |
ed235875 | 184 | static unsigned long soft_lockup_nmi_warn; |
58687acb | 185 | |
58687acb DZ |
186 | static int __init softlockup_panic_setup(char *str) |
187 | { | |
188 | softlockup_panic = simple_strtoul(str, NULL, 0); | |
58687acb DZ |
189 | return 1; |
190 | } | |
191 | __setup("softlockup_panic=", softlockup_panic_setup); | |
192 | ||
193 | static int __init nowatchdog_setup(char *str) | |
194 | { | |
09154985 | 195 | watchdog_user_enabled = 0; |
58687acb DZ |
196 | return 1; |
197 | } | |
198 | __setup("nowatchdog", nowatchdog_setup); | |
199 | ||
58687acb DZ |
200 | static int __init nosoftlockup_setup(char *str) |
201 | { | |
09154985 | 202 | soft_watchdog_user_enabled = 0; |
58687acb DZ |
203 | return 1; |
204 | } | |
205 | __setup("nosoftlockup", nosoftlockup_setup); | |
195daf66 | 206 | |
ed235875 | 207 | #ifdef CONFIG_SMP |
368a7e2c TG |
208 | int __read_mostly sysctl_softlockup_all_cpu_backtrace; |
209 | ||
ed235875 AT |
210 | static int __init softlockup_all_cpu_backtrace_setup(char *str) |
211 | { | |
368a7e2c | 212 | sysctl_softlockup_all_cpu_backtrace = !!simple_strtol(str, NULL, 0); |
ed235875 AT |
213 | return 1; |
214 | } | |
215 | __setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup); | |
05a4a952 | 216 | #endif |
58687acb | 217 | |
941154bd TG |
218 | static void __lockup_detector_cleanup(void); |
219 | ||
4eec42f3 MSB |
220 | /* |
221 | * Hard-lockup warnings should be triggered after just a few seconds. Soft- | |
222 | * lockups can have false positives under extreme conditions. So we generally | |
223 | * want a higher threshold for soft lockups than for hard lockups. So we couple | |
224 | * the thresholds with a factor: we make the soft threshold twice the amount of | |
225 | * time the hard threshold is. | |
226 | */ | |
6e9101ae | 227 | static int get_softlockup_thresh(void) |
4eec42f3 MSB |
228 | { |
229 | return watchdog_thresh * 2; | |
230 | } | |
58687acb DZ |
231 | |
232 | /* | |
233 | * Returns seconds, approximately. We don't need nanosecond | |
234 | * resolution, and we don't need to waste time with a big divide when | |
235 | * 2^30ns == 1.074s. | |
236 | */ | |
c06b4f19 | 237 | static unsigned long get_timestamp(void) |
58687acb | 238 | { |
545a2bf7 | 239 | return running_clock() >> 30LL; /* 2^30 ~= 10^9 */ |
58687acb DZ |
240 | } |
241 | ||
0f34c400 | 242 | static void set_sample_period(void) |
58687acb DZ |
243 | { |
244 | /* | |
586692a5 | 245 | * convert watchdog_thresh from seconds to ns |
86f5e6a7 FLVC |
246 | * the divide by 5 is to give hrtimer several chances (two |
247 | * or three with the current relation between the soft | |
248 | * and hard thresholds) to increment before the | |
249 | * hardlockup detector generates a warning | |
58687acb | 250 | */ |
0f34c400 | 251 | sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); |
7edaeb68 | 252 | watchdog_update_hrtimer_threshold(sample_period); |
58687acb DZ |
253 | } |
254 | ||
255 | /* Commands for resetting the watchdog */ | |
256 | static void __touch_watchdog(void) | |
257 | { | |
c06b4f19 | 258 | __this_cpu_write(watchdog_touch_ts, get_timestamp()); |
58687acb DZ |
259 | } |
260 | ||
03e0d461 TH |
261 | /** |
262 | * touch_softlockup_watchdog_sched - touch watchdog on scheduler stalls | |
263 | * | |
264 | * Call when the scheduler may have stalled for legitimate reasons | |
265 | * preventing the watchdog task from executing - e.g. the scheduler | |
266 | * entering idle state. This should only be used for scheduler events. | |
267 | * Use touch_softlockup_watchdog() for everything else. | |
268 | */ | |
269 | void touch_softlockup_watchdog_sched(void) | |
58687acb | 270 | { |
7861144b AM |
271 | /* |
272 | * Preemption can be enabled. It doesn't matter which CPU's timestamp | |
273 | * gets zeroed here, so use the raw_ operation. | |
274 | */ | |
275 | raw_cpu_write(watchdog_touch_ts, 0); | |
58687acb | 276 | } |
03e0d461 TH |
277 | |
278 | void touch_softlockup_watchdog(void) | |
279 | { | |
280 | touch_softlockup_watchdog_sched(); | |
82607adc | 281 | wq_watchdog_touch(raw_smp_processor_id()); |
03e0d461 | 282 | } |
0167c781 | 283 | EXPORT_SYMBOL(touch_softlockup_watchdog); |
58687acb | 284 | |
332fbdbc | 285 | void touch_all_softlockup_watchdogs(void) |
58687acb DZ |
286 | { |
287 | int cpu; | |
288 | ||
289 | /* | |
d57108d4 TG |
290 | * watchdog_mutex cannpt be taken here, as this might be called |
291 | * from (soft)interrupt context, so the access to | |
292 | * watchdog_allowed_cpumask might race with a concurrent update. | |
293 | * | |
294 | * The watchdog time stamp can race against a concurrent real | |
295 | * update as well, the only side effect might be a cycle delay for | |
296 | * the softlockup check. | |
58687acb | 297 | */ |
d57108d4 | 298 | for_each_cpu(cpu, &watchdog_allowed_mask) |
58687acb | 299 | per_cpu(watchdog_touch_ts, cpu) = 0; |
82607adc | 300 | wq_watchdog_touch(-1); |
58687acb DZ |
301 | } |
302 | ||
58687acb DZ |
303 | void touch_softlockup_watchdog_sync(void) |
304 | { | |
f7f66b05 CL |
305 | __this_cpu_write(softlockup_touch_sync, true); |
306 | __this_cpu_write(watchdog_touch_ts, 0); | |
58687acb DZ |
307 | } |
308 | ||
26e09c6e | 309 | static int is_softlockup(unsigned long touch_ts) |
58687acb | 310 | { |
c06b4f19 | 311 | unsigned long now = get_timestamp(); |
58687acb | 312 | |
39d2da21 | 313 | if ((watchdog_enabled & SOFT_WATCHDOG_ENABLED) && watchdog_thresh){ |
195daf66 UO |
314 | /* Warn about unreasonable delays. */ |
315 | if (time_after(now, touch_ts + get_softlockup_thresh())) | |
316 | return now - touch_ts; | |
317 | } | |
58687acb DZ |
318 | return 0; |
319 | } | |
320 | ||
05a4a952 NP |
321 | /* watchdog detector functions */ |
322 | bool is_hardlockup(void) | |
58687acb | 323 | { |
05a4a952 | 324 | unsigned long hrint = __this_cpu_read(hrtimer_interrupts); |
bcd951cf | 325 | |
05a4a952 NP |
326 | if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) |
327 | return true; | |
328 | ||
329 | __this_cpu_write(hrtimer_interrupts_saved, hrint); | |
330 | return false; | |
73ce0511 | 331 | } |
05a4a952 NP |
332 | |
333 | static void watchdog_interrupt_count(void) | |
73ce0511 | 334 | { |
05a4a952 | 335 | __this_cpu_inc(hrtimer_interrupts); |
73ce0511 | 336 | } |
58687acb DZ |
337 | |
338 | /* watchdog kicker functions */ | |
339 | static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) | |
340 | { | |
909ea964 | 341 | unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts); |
58687acb DZ |
342 | struct pt_regs *regs = get_irq_regs(); |
343 | int duration; | |
ed235875 | 344 | int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; |
58687acb | 345 | |
01f0a027 | 346 | if (!watchdog_enabled) |
b94f5118 DZ |
347 | return HRTIMER_NORESTART; |
348 | ||
58687acb DZ |
349 | /* kick the hardlockup detector */ |
350 | watchdog_interrupt_count(); | |
351 | ||
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 */ |
b1a8de1f | 391 | if (__this_cpu_read(soft_watchdog_warn) == true) { |
392 | /* | |
393 | * When multiple processes are causing softlockups the | |
394 | * softlockup detector only warns on the first one | |
395 | * because the code relies on a full quiet cycle to | |
396 | * re-arm. The second process prevents the quiet cycle | |
397 | * and never gets reported. Use task pointers to detect | |
398 | * this. | |
399 | */ | |
400 | if (__this_cpu_read(softlockup_task_ptr_saved) != | |
401 | current) { | |
402 | __this_cpu_write(soft_watchdog_warn, false); | |
403 | __touch_watchdog(); | |
404 | } | |
58687acb | 405 | return HRTIMER_RESTART; |
b1a8de1f | 406 | } |
58687acb | 407 | |
ed235875 AT |
408 | if (softlockup_all_cpu_backtrace) { |
409 | /* Prevent multiple soft-lockup reports if one cpu is already | |
410 | * engaged in dumping cpu back traces | |
411 | */ | |
412 | if (test_and_set_bit(0, &soft_lockup_nmi_warn)) { | |
413 | /* Someone else will report us. Let's give up */ | |
414 | __this_cpu_write(soft_watchdog_warn, true); | |
415 | return HRTIMER_RESTART; | |
416 | } | |
417 | } | |
418 | ||
656c3b79 | 419 | pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", |
26e09c6e | 420 | smp_processor_id(), duration, |
58687acb | 421 | current->comm, task_pid_nr(current)); |
b1a8de1f | 422 | __this_cpu_write(softlockup_task_ptr_saved, current); |
58687acb DZ |
423 | print_modules(); |
424 | print_irqtrace_events(current); | |
425 | if (regs) | |
426 | show_regs(regs); | |
427 | else | |
428 | dump_stack(); | |
429 | ||
ed235875 AT |
430 | if (softlockup_all_cpu_backtrace) { |
431 | /* Avoid generating two back traces for current | |
432 | * given that one is already made above | |
433 | */ | |
434 | trigger_allbutself_cpu_backtrace(); | |
435 | ||
436 | clear_bit(0, &soft_lockup_nmi_warn); | |
437 | /* Barrier to sync with other cpus */ | |
438 | smp_mb__after_atomic(); | |
439 | } | |
440 | ||
69361eef | 441 | add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK); |
58687acb DZ |
442 | if (softlockup_panic) |
443 | panic("softlockup: hung tasks"); | |
909ea964 | 444 | __this_cpu_write(soft_watchdog_warn, true); |
58687acb | 445 | } else |
909ea964 | 446 | __this_cpu_write(soft_watchdog_warn, false); |
58687acb DZ |
447 | |
448 | return HRTIMER_RESTART; | |
449 | } | |
450 | ||
bcd951cf TG |
451 | static void watchdog_set_prio(unsigned int policy, unsigned int prio) |
452 | { | |
453 | struct sched_param param = { .sched_priority = prio }; | |
58687acb | 454 | |
bcd951cf TG |
455 | sched_setscheduler(current, policy, ¶m); |
456 | } | |
457 | ||
458 | static void watchdog_enable(unsigned int cpu) | |
58687acb | 459 | { |
01f0a027 | 460 | struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer); |
58687acb | 461 | |
01f0a027 TG |
462 | /* |
463 | * Start the timer first to prevent the NMI watchdog triggering | |
464 | * before the timer has a chance to fire. | |
465 | */ | |
3935e895 BM |
466 | hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
467 | hrtimer->function = watchdog_timer_fn; | |
01f0a027 TG |
468 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
469 | HRTIMER_MODE_REL_PINNED); | |
3935e895 | 470 | |
01f0a027 TG |
471 | /* Initialize timestamp */ |
472 | __touch_watchdog(); | |
bcd951cf | 473 | /* Enable the perf event */ |
146c9d0e TG |
474 | if (watchdog_enabled & NMI_WATCHDOG_ENABLED) |
475 | watchdog_nmi_enable(cpu); | |
58687acb | 476 | |
bcd951cf | 477 | watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1); |
bcd951cf | 478 | } |
58687acb | 479 | |
bcd951cf TG |
480 | static void watchdog_disable(unsigned int cpu) |
481 | { | |
01f0a027 | 482 | struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer); |
58687acb | 483 | |
bcd951cf | 484 | watchdog_set_prio(SCHED_NORMAL, 0); |
01f0a027 TG |
485 | /* |
486 | * Disable the perf event first. That prevents that a large delay | |
487 | * between disabling the timer and disabling the perf event causes | |
488 | * the perf NMI to detect a false positive. | |
489 | */ | |
bcd951cf | 490 | watchdog_nmi_disable(cpu); |
01f0a027 | 491 | hrtimer_cancel(hrtimer); |
58687acb DZ |
492 | } |
493 | ||
b8900bc0 FW |
494 | static void watchdog_cleanup(unsigned int cpu, bool online) |
495 | { | |
496 | watchdog_disable(cpu); | |
497 | } | |
498 | ||
bcd951cf TG |
499 | static int watchdog_should_run(unsigned int cpu) |
500 | { | |
501 | return __this_cpu_read(hrtimer_interrupts) != | |
502 | __this_cpu_read(soft_lockup_hrtimer_cnt); | |
503 | } | |
504 | ||
505 | /* | |
506 | * The watchdog thread function - touches the timestamp. | |
507 | * | |
0f34c400 | 508 | * It only runs once every sample_period seconds (4 seconds by |
bcd951cf TG |
509 | * default) to reset the softlockup timestamp. If this gets delayed |
510 | * for more than 2*watchdog_thresh seconds then the debug-printout | |
511 | * triggers in watchdog_timer_fn(). | |
512 | */ | |
513 | static void watchdog(unsigned int cpu) | |
514 | { | |
515 | __this_cpu_write(soft_lockup_hrtimer_cnt, | |
516 | __this_cpu_read(hrtimer_interrupts)); | |
517 | __touch_watchdog(); | |
518 | } | |
58687acb | 519 | |
b8900bc0 FW |
520 | static struct smp_hotplug_thread watchdog_threads = { |
521 | .store = &softlockup_watchdog, | |
522 | .thread_should_run = watchdog_should_run, | |
523 | .thread_fn = watchdog, | |
524 | .thread_comm = "watchdog/%u", | |
525 | .setup = watchdog_enable, | |
526 | .cleanup = watchdog_cleanup, | |
527 | .park = watchdog_disable, | |
528 | .unpark = watchdog_enable, | |
529 | }; | |
530 | ||
2eb2527f TG |
531 | static void softlockup_update_smpboot_threads(void) |
532 | { | |
533 | lockdep_assert_held(&watchdog_mutex); | |
534 | ||
535 | if (!softlockup_threads_initialized) | |
536 | return; | |
537 | ||
538 | smpboot_update_cpumask_percpu_thread(&watchdog_threads, | |
539 | &watchdog_allowed_mask); | |
2eb2527f TG |
540 | } |
541 | ||
542 | /* Temporarily park all watchdog threads */ | |
543 | static void softlockup_park_all_threads(void) | |
544 | { | |
545 | cpumask_clear(&watchdog_allowed_mask); | |
546 | softlockup_update_smpboot_threads(); | |
547 | } | |
548 | ||
e8b62b2d TG |
549 | /* Unpark enabled threads */ |
550 | static void softlockup_unpark_threads(void) | |
2eb2527f TG |
551 | { |
552 | cpumask_copy(&watchdog_allowed_mask, &watchdog_cpumask); | |
553 | softlockup_update_smpboot_threads(); | |
554 | } | |
555 | ||
5587185d | 556 | static void lockup_detector_reconfigure(void) |
2eb2527f | 557 | { |
e31d6883 | 558 | cpus_read_lock(); |
6b9dc480 | 559 | watchdog_nmi_stop(); |
2eb2527f TG |
560 | softlockup_park_all_threads(); |
561 | set_sample_period(); | |
09154985 TG |
562 | lockup_detector_update_enable(); |
563 | if (watchdog_enabled && watchdog_thresh) | |
e8b62b2d | 564 | softlockup_unpark_threads(); |
6b9dc480 | 565 | watchdog_nmi_start(); |
e31d6883 TG |
566 | cpus_read_unlock(); |
567 | /* | |
568 | * Must be called outside the cpus locked section to prevent | |
569 | * recursive locking in the perf code. | |
570 | */ | |
571 | __lockup_detector_cleanup(); | |
2eb2527f TG |
572 | } |
573 | ||
574 | /* | |
5587185d | 575 | * Create the watchdog thread infrastructure and configure the detector(s). |
2eb2527f TG |
576 | * |
577 | * The threads are not unparked as watchdog_allowed_mask is empty. When | |
578 | * the threads are sucessfully initialized, take the proper locks and | |
579 | * unpark the threads in the watchdog_cpumask if the watchdog is enabled. | |
580 | */ | |
5587185d | 581 | static __init void lockup_detector_setup(void) |
2eb2527f TG |
582 | { |
583 | int ret; | |
584 | ||
585 | /* | |
586 | * If sysctl is off and watchdog got disabled on the command line, | |
587 | * nothing to do here. | |
588 | */ | |
09154985 TG |
589 | lockup_detector_update_enable(); |
590 | ||
2eb2527f TG |
591 | if (!IS_ENABLED(CONFIG_SYSCTL) && |
592 | !(watchdog_enabled && watchdog_thresh)) | |
593 | return; | |
594 | ||
595 | ret = smpboot_register_percpu_thread_cpumask(&watchdog_threads, | |
596 | &watchdog_allowed_mask); | |
597 | if (ret) { | |
598 | pr_err("Failed to initialize soft lockup detector threads\n"); | |
599 | return; | |
600 | } | |
601 | ||
602 | mutex_lock(&watchdog_mutex); | |
603 | softlockup_threads_initialized = true; | |
5587185d | 604 | lockup_detector_reconfigure(); |
2eb2527f TG |
605 | mutex_unlock(&watchdog_mutex); |
606 | } | |
607 | ||
2b9d7f23 TG |
608 | #else /* CONFIG_SOFTLOCKUP_DETECTOR */ |
609 | static inline int watchdog_park_threads(void) { return 0; } | |
610 | static inline void watchdog_unpark_threads(void) { } | |
611 | static inline int watchdog_enable_all_cpus(void) { return 0; } | |
612 | static inline void watchdog_disable_all_cpus(void) { } | |
5587185d | 613 | static void lockup_detector_reconfigure(void) |
6592ad2f | 614 | { |
e31d6883 | 615 | cpus_read_lock(); |
6b9dc480 | 616 | watchdog_nmi_stop(); |
09154985 | 617 | lockup_detector_update_enable(); |
6b9dc480 | 618 | watchdog_nmi_start(); |
e31d6883 | 619 | cpus_read_unlock(); |
6592ad2f | 620 | } |
5587185d | 621 | static inline void lockup_detector_setup(void) |
34ddaa3e | 622 | { |
5587185d | 623 | lockup_detector_reconfigure(); |
34ddaa3e | 624 | } |
2b9d7f23 | 625 | #endif /* !CONFIG_SOFTLOCKUP_DETECTOR */ |
05a4a952 | 626 | |
941154bd TG |
627 | static void __lockup_detector_cleanup(void) |
628 | { | |
629 | lockdep_assert_held(&watchdog_mutex); | |
630 | hardlockup_detector_perf_cleanup(); | |
631 | } | |
632 | ||
633 | /** | |
634 | * lockup_detector_cleanup - Cleanup after cpu hotplug or sysctl changes | |
635 | * | |
636 | * Caller must not hold the cpu hotplug rwsem. | |
637 | */ | |
638 | void lockup_detector_cleanup(void) | |
639 | { | |
640 | mutex_lock(&watchdog_mutex); | |
641 | __lockup_detector_cleanup(); | |
642 | mutex_unlock(&watchdog_mutex); | |
643 | } | |
644 | ||
6554fd8c TG |
645 | /** |
646 | * lockup_detector_soft_poweroff - Interface to stop lockup detector(s) | |
647 | * | |
648 | * Special interface for parisc. It prevents lockup detector warnings from | |
649 | * the default pm_poweroff() function which busy loops forever. | |
650 | */ | |
651 | void lockup_detector_soft_poweroff(void) | |
652 | { | |
653 | watchdog_enabled = 0; | |
654 | } | |
655 | ||
58cf690a UO |
656 | #ifdef CONFIG_SYSCTL |
657 | ||
e8b62b2d | 658 | /* Propagate any changes to the watchdog threads */ |
d57108d4 | 659 | static void proc_watchdog_update(void) |
a0c9cbb9 | 660 | { |
e8b62b2d TG |
661 | /* Remove impossible cpus to keep sysctl output clean. */ |
662 | cpumask_and(&watchdog_cpumask, &watchdog_cpumask, cpu_possible_mask); | |
5587185d | 663 | lockup_detector_reconfigure(); |
a0c9cbb9 UO |
664 | } |
665 | ||
ef246a21 UO |
666 | /* |
667 | * common function for watchdog, nmi_watchdog and soft_watchdog parameter | |
668 | * | |
7feeb9cd TG |
669 | * caller | table->data points to | 'which' |
670 | * -------------------|----------------------------|-------------------------- | |
671 | * proc_watchdog | watchdog_user_enabled | NMI_WATCHDOG_ENABLED | | |
672 | * | | SOFT_WATCHDOG_ENABLED | |
673 | * -------------------|----------------------------|-------------------------- | |
674 | * proc_nmi_watchdog | nmi_watchdog_user_enabled | NMI_WATCHDOG_ENABLED | |
675 | * -------------------|----------------------------|-------------------------- | |
676 | * proc_soft_watchdog | soft_watchdog_user_enabled | SOFT_WATCHDOG_ENABLED | |
ef246a21 UO |
677 | */ |
678 | static int proc_watchdog_common(int which, struct ctl_table *table, int write, | |
679 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
680 | { | |
09154985 | 681 | int err, old, *param = table->data; |
ef246a21 | 682 | |
946d1977 | 683 | mutex_lock(&watchdog_mutex); |
ef246a21 | 684 | |
ef246a21 | 685 | if (!write) { |
09154985 TG |
686 | /* |
687 | * On read synchronize the userspace interface. This is a | |
688 | * racy snapshot. | |
689 | */ | |
690 | *param = (watchdog_enabled & which) != 0; | |
ef246a21 UO |
691 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
692 | } else { | |
09154985 | 693 | old = READ_ONCE(*param); |
ef246a21 | 694 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
09154985 | 695 | if (!err && old != READ_ONCE(*param)) |
d57108d4 | 696 | proc_watchdog_update(); |
ef246a21 | 697 | } |
946d1977 | 698 | mutex_unlock(&watchdog_mutex); |
ef246a21 UO |
699 | return err; |
700 | } | |
701 | ||
83a80a39 UO |
702 | /* |
703 | * /proc/sys/kernel/watchdog | |
704 | */ | |
705 | int proc_watchdog(struct ctl_table *table, int write, | |
706 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
707 | { | |
708 | return proc_watchdog_common(NMI_WATCHDOG_ENABLED|SOFT_WATCHDOG_ENABLED, | |
709 | table, write, buffer, lenp, ppos); | |
710 | } | |
711 | ||
712 | /* | |
713 | * /proc/sys/kernel/nmi_watchdog | |
58687acb | 714 | */ |
83a80a39 UO |
715 | int proc_nmi_watchdog(struct ctl_table *table, int write, |
716 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
717 | { | |
a994a314 TG |
718 | if (!nmi_watchdog_available && write) |
719 | return -ENOTSUPP; | |
83a80a39 UO |
720 | return proc_watchdog_common(NMI_WATCHDOG_ENABLED, |
721 | table, write, buffer, lenp, ppos); | |
722 | } | |
723 | ||
724 | /* | |
725 | * /proc/sys/kernel/soft_watchdog | |
726 | */ | |
727 | int proc_soft_watchdog(struct ctl_table *table, int write, | |
728 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
729 | { | |
730 | return proc_watchdog_common(SOFT_WATCHDOG_ENABLED, | |
731 | table, write, buffer, lenp, ppos); | |
732 | } | |
58687acb | 733 | |
83a80a39 UO |
734 | /* |
735 | * /proc/sys/kernel/watchdog_thresh | |
736 | */ | |
737 | int proc_watchdog_thresh(struct ctl_table *table, int write, | |
738 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
58687acb | 739 | { |
d57108d4 | 740 | int err, old; |
58687acb | 741 | |
946d1977 | 742 | mutex_lock(&watchdog_mutex); |
bcd951cf | 743 | |
d57108d4 | 744 | old = READ_ONCE(watchdog_thresh); |
b8900bc0 | 745 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
83a80a39 | 746 | |
d57108d4 TG |
747 | if (!err && write && old != READ_ONCE(watchdog_thresh)) |
748 | proc_watchdog_update(); | |
e04ab2bc | 749 | |
946d1977 | 750 | mutex_unlock(&watchdog_mutex); |
b8900bc0 | 751 | return err; |
58687acb | 752 | } |
fe4ba3c3 CM |
753 | |
754 | /* | |
755 | * The cpumask is the mask of possible cpus that the watchdog can run | |
756 | * on, not the mask of cpus it is actually running on. This allows the | |
757 | * user to specify a mask that will include cpus that have not yet | |
758 | * been brought online, if desired. | |
759 | */ | |
760 | int proc_watchdog_cpumask(struct ctl_table *table, int write, | |
761 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
762 | { | |
763 | int err; | |
764 | ||
946d1977 | 765 | mutex_lock(&watchdog_mutex); |
8c073d27 | 766 | |
fe4ba3c3 | 767 | err = proc_do_large_bitmap(table, write, buffer, lenp, ppos); |
05ba3de7 | 768 | if (!err && write) |
e8b62b2d | 769 | proc_watchdog_update(); |
5490125d | 770 | |
946d1977 | 771 | mutex_unlock(&watchdog_mutex); |
fe4ba3c3 CM |
772 | return err; |
773 | } | |
58687acb DZ |
774 | #endif /* CONFIG_SYSCTL */ |
775 | ||
004417a6 | 776 | void __init lockup_detector_init(void) |
58687acb | 777 | { |
13316b31 | 778 | if (tick_nohz_full_enabled()) |
314b08ff | 779 | pr_info("Disabling watchdog on nohz_full cores by default\n"); |
13316b31 | 780 | |
de201559 FW |
781 | cpumask_copy(&watchdog_cpumask, |
782 | housekeeping_cpumask(HK_FLAG_TIMER)); | |
fe4ba3c3 | 783 | |
a994a314 TG |
784 | if (!watchdog_nmi_probe()) |
785 | nmi_watchdog_available = true; | |
5587185d | 786 | lockup_detector_setup(); |
58687acb | 787 | } |