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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> | |
fe4ba3c3 | 21 | #include <linux/tick.h> |
e6017571 | 22 | #include <linux/sched/clock.h> |
b17b0153 | 23 | #include <linux/sched/debug.h> |
78634061 | 24 | #include <linux/sched/isolation.h> |
9cf57731 | 25 | #include <linux/stop_machine.h> |
58687acb DZ |
26 | |
27 | #include <asm/irq_regs.h> | |
5d1c0f4a | 28 | #include <linux/kvm_para.h> |
58687acb | 29 | |
946d1977 | 30 | static DEFINE_MUTEX(watchdog_mutex); |
ab992dc3 | 31 | |
05a4a952 | 32 | #if defined(CONFIG_HARDLOCKUP_DETECTOR) || defined(CONFIG_HAVE_NMI_WATCHDOG) |
09154985 TG |
33 | # define WATCHDOG_DEFAULT (SOFT_WATCHDOG_ENABLED | NMI_WATCHDOG_ENABLED) |
34 | # define NMI_WATCHDOG_DEFAULT 1 | |
84d56e66 | 35 | #else |
09154985 TG |
36 | # define WATCHDOG_DEFAULT (SOFT_WATCHDOG_ENABLED) |
37 | # define NMI_WATCHDOG_DEFAULT 0 | |
84d56e66 | 38 | #endif |
05a4a952 | 39 | |
09154985 TG |
40 | unsigned long __read_mostly watchdog_enabled; |
41 | int __read_mostly watchdog_user_enabled = 1; | |
42 | int __read_mostly nmi_watchdog_user_enabled = NMI_WATCHDOG_DEFAULT; | |
43 | int __read_mostly soft_watchdog_user_enabled = 1; | |
7feeb9cd | 44 | int __read_mostly watchdog_thresh = 10; |
a994a314 | 45 | int __read_mostly nmi_watchdog_available; |
7feeb9cd TG |
46 | |
47 | struct cpumask watchdog_allowed_mask __read_mostly; | |
7feeb9cd TG |
48 | |
49 | struct cpumask watchdog_cpumask __read_mostly; | |
50 | unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask); | |
51 | ||
05a4a952 | 52 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
05a4a952 NP |
53 | /* |
54 | * Should we panic when a soft-lockup or hard-lockup occurs: | |
55 | */ | |
56 | unsigned int __read_mostly hardlockup_panic = | |
57 | CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE; | |
58 | /* | |
59 | * We may not want to enable hard lockup detection by default in all cases, | |
60 | * for example when running the kernel as a guest on a hypervisor. In these | |
61 | * cases this function can be called to disable hard lockup detection. This | |
62 | * function should only be executed once by the boot processor before the | |
63 | * kernel command line parameters are parsed, because otherwise it is not | |
64 | * possible to override this in hardlockup_panic_setup(). | |
65 | */ | |
7a355820 | 66 | void __init hardlockup_detector_disable(void) |
05a4a952 | 67 | { |
09154985 | 68 | nmi_watchdog_user_enabled = 0; |
05a4a952 NP |
69 | } |
70 | ||
71 | static int __init hardlockup_panic_setup(char *str) | |
72 | { | |
73 | if (!strncmp(str, "panic", 5)) | |
74 | hardlockup_panic = 1; | |
75 | else if (!strncmp(str, "nopanic", 7)) | |
76 | hardlockup_panic = 0; | |
77 | else if (!strncmp(str, "0", 1)) | |
09154985 | 78 | nmi_watchdog_user_enabled = 0; |
05a4a952 | 79 | else if (!strncmp(str, "1", 1)) |
09154985 | 80 | nmi_watchdog_user_enabled = 1; |
05a4a952 NP |
81 | return 1; |
82 | } | |
83 | __setup("nmi_watchdog=", hardlockup_panic_setup); | |
84 | ||
368a7e2c TG |
85 | # ifdef CONFIG_SMP |
86 | int __read_mostly sysctl_hardlockup_all_cpu_backtrace; | |
05a4a952 | 87 | |
368a7e2c TG |
88 | static int __init hardlockup_all_cpu_backtrace_setup(char *str) |
89 | { | |
90 | sysctl_hardlockup_all_cpu_backtrace = !!simple_strtol(str, NULL, 0); | |
91 | return 1; | |
92 | } | |
93 | __setup("hardlockup_all_cpu_backtrace=", hardlockup_all_cpu_backtrace_setup); | |
94 | # endif /* CONFIG_SMP */ | |
95 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ | |
05a4a952 | 96 | |
05a4a952 NP |
97 | /* |
98 | * These functions can be overridden if an architecture implements its | |
99 | * own hardlockup detector. | |
a10a842f NP |
100 | * |
101 | * watchdog_nmi_enable/disable can be implemented to start and stop when | |
102 | * softlockup watchdog threads start and stop. The arch must select the | |
103 | * SOFTLOCKUP_DETECTOR Kconfig. | |
05a4a952 NP |
104 | */ |
105 | int __weak watchdog_nmi_enable(unsigned int cpu) | |
106 | { | |
146c9d0e | 107 | hardlockup_detector_perf_enable(); |
05a4a952 NP |
108 | return 0; |
109 | } | |
941154bd | 110 | |
05a4a952 NP |
111 | void __weak watchdog_nmi_disable(unsigned int cpu) |
112 | { | |
941154bd | 113 | hardlockup_detector_perf_disable(); |
05a4a952 NP |
114 | } |
115 | ||
a994a314 TG |
116 | /* Return 0, if a NMI watchdog is available. Error code otherwise */ |
117 | int __weak __init watchdog_nmi_probe(void) | |
118 | { | |
119 | return hardlockup_detector_perf_init(); | |
120 | } | |
121 | ||
6592ad2f | 122 | /** |
6b9dc480 | 123 | * watchdog_nmi_stop - Stop the watchdog for reconfiguration |
6592ad2f | 124 | * |
6b9dc480 TG |
125 | * The reconfiguration steps are: |
126 | * watchdog_nmi_stop(); | |
6592ad2f | 127 | * update_variables(); |
6b9dc480 TG |
128 | * watchdog_nmi_start(); |
129 | */ | |
130 | void __weak watchdog_nmi_stop(void) { } | |
131 | ||
132 | /** | |
133 | * watchdog_nmi_start - Start the watchdog after reconfiguration | |
6592ad2f | 134 | * |
6b9dc480 TG |
135 | * Counterpart to watchdog_nmi_stop(). |
136 | * | |
137 | * The following variables have been updated in update_variables() and | |
138 | * contain the currently valid configuration: | |
7feeb9cd | 139 | * - watchdog_enabled |
a10a842f NP |
140 | * - watchdog_thresh |
141 | * - watchdog_cpumask | |
a10a842f | 142 | */ |
6b9dc480 | 143 | void __weak watchdog_nmi_start(void) { } |
a10a842f | 144 | |
09154985 TG |
145 | /** |
146 | * lockup_detector_update_enable - Update the sysctl enable bit | |
147 | * | |
148 | * Caller needs to make sure that the NMI/perf watchdogs are off, so this | |
149 | * can't race with watchdog_nmi_disable(). | |
150 | */ | |
151 | static void lockup_detector_update_enable(void) | |
152 | { | |
153 | watchdog_enabled = 0; | |
154 | if (!watchdog_user_enabled) | |
155 | return; | |
a994a314 | 156 | if (nmi_watchdog_available && nmi_watchdog_user_enabled) |
09154985 TG |
157 | watchdog_enabled |= NMI_WATCHDOG_ENABLED; |
158 | if (soft_watchdog_user_enabled) | |
159 | watchdog_enabled |= SOFT_WATCHDOG_ENABLED; | |
160 | } | |
161 | ||
05a4a952 NP |
162 | #ifdef CONFIG_SOFTLOCKUP_DETECTOR |
163 | ||
2b9d7f23 TG |
164 | /* Global variables, exported for sysctl */ |
165 | unsigned int __read_mostly softlockup_panic = | |
166 | CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE; | |
2eb2527f | 167 | |
9cf57731 | 168 | static bool softlockup_initialized __read_mostly; |
0f34c400 | 169 | static u64 __read_mostly sample_period; |
58687acb DZ |
170 | |
171 | static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); | |
58687acb DZ |
172 | static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer); |
173 | static DEFINE_PER_CPU(bool, softlockup_touch_sync); | |
58687acb | 174 | static DEFINE_PER_CPU(bool, soft_watchdog_warn); |
bcd951cf TG |
175 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); |
176 | static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt); | |
b1a8de1f | 177 | static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved); |
58687acb | 178 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); |
ed235875 | 179 | static unsigned long soft_lockup_nmi_warn; |
58687acb | 180 | |
58687acb DZ |
181 | static int __init softlockup_panic_setup(char *str) |
182 | { | |
183 | softlockup_panic = simple_strtoul(str, NULL, 0); | |
58687acb DZ |
184 | return 1; |
185 | } | |
186 | __setup("softlockup_panic=", softlockup_panic_setup); | |
187 | ||
188 | static int __init nowatchdog_setup(char *str) | |
189 | { | |
09154985 | 190 | watchdog_user_enabled = 0; |
58687acb DZ |
191 | return 1; |
192 | } | |
193 | __setup("nowatchdog", nowatchdog_setup); | |
194 | ||
58687acb DZ |
195 | static int __init nosoftlockup_setup(char *str) |
196 | { | |
09154985 | 197 | soft_watchdog_user_enabled = 0; |
58687acb DZ |
198 | return 1; |
199 | } | |
200 | __setup("nosoftlockup", nosoftlockup_setup); | |
195daf66 | 201 | |
ed235875 | 202 | #ifdef CONFIG_SMP |
368a7e2c TG |
203 | int __read_mostly sysctl_softlockup_all_cpu_backtrace; |
204 | ||
ed235875 AT |
205 | static int __init softlockup_all_cpu_backtrace_setup(char *str) |
206 | { | |
368a7e2c | 207 | sysctl_softlockup_all_cpu_backtrace = !!simple_strtol(str, NULL, 0); |
ed235875 AT |
208 | return 1; |
209 | } | |
210 | __setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup); | |
05a4a952 | 211 | #endif |
58687acb | 212 | |
941154bd TG |
213 | static void __lockup_detector_cleanup(void); |
214 | ||
4eec42f3 MSB |
215 | /* |
216 | * Hard-lockup warnings should be triggered after just a few seconds. Soft- | |
217 | * lockups can have false positives under extreme conditions. So we generally | |
218 | * want a higher threshold for soft lockups than for hard lockups. So we couple | |
219 | * the thresholds with a factor: we make the soft threshold twice the amount of | |
220 | * time the hard threshold is. | |
221 | */ | |
6e9101ae | 222 | static int get_softlockup_thresh(void) |
4eec42f3 MSB |
223 | { |
224 | return watchdog_thresh * 2; | |
225 | } | |
58687acb DZ |
226 | |
227 | /* | |
228 | * Returns seconds, approximately. We don't need nanosecond | |
229 | * resolution, and we don't need to waste time with a big divide when | |
230 | * 2^30ns == 1.074s. | |
231 | */ | |
c06b4f19 | 232 | static unsigned long get_timestamp(void) |
58687acb | 233 | { |
545a2bf7 | 234 | return running_clock() >> 30LL; /* 2^30 ~= 10^9 */ |
58687acb DZ |
235 | } |
236 | ||
0f34c400 | 237 | static void set_sample_period(void) |
58687acb DZ |
238 | { |
239 | /* | |
586692a5 | 240 | * convert watchdog_thresh from seconds to ns |
86f5e6a7 FLVC |
241 | * the divide by 5 is to give hrtimer several chances (two |
242 | * or three with the current relation between the soft | |
243 | * and hard thresholds) to increment before the | |
244 | * hardlockup detector generates a warning | |
58687acb | 245 | */ |
0f34c400 | 246 | sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); |
7edaeb68 | 247 | watchdog_update_hrtimer_threshold(sample_period); |
58687acb DZ |
248 | } |
249 | ||
250 | /* Commands for resetting the watchdog */ | |
251 | static void __touch_watchdog(void) | |
252 | { | |
c06b4f19 | 253 | __this_cpu_write(watchdog_touch_ts, get_timestamp()); |
58687acb DZ |
254 | } |
255 | ||
03e0d461 TH |
256 | /** |
257 | * touch_softlockup_watchdog_sched - touch watchdog on scheduler stalls | |
258 | * | |
259 | * Call when the scheduler may have stalled for legitimate reasons | |
260 | * preventing the watchdog task from executing - e.g. the scheduler | |
261 | * entering idle state. This should only be used for scheduler events. | |
262 | * Use touch_softlockup_watchdog() for everything else. | |
263 | */ | |
264 | void touch_softlockup_watchdog_sched(void) | |
58687acb | 265 | { |
7861144b AM |
266 | /* |
267 | * Preemption can be enabled. It doesn't matter which CPU's timestamp | |
268 | * gets zeroed here, so use the raw_ operation. | |
269 | */ | |
270 | raw_cpu_write(watchdog_touch_ts, 0); | |
58687acb | 271 | } |
03e0d461 TH |
272 | |
273 | void touch_softlockup_watchdog(void) | |
274 | { | |
275 | touch_softlockup_watchdog_sched(); | |
82607adc | 276 | wq_watchdog_touch(raw_smp_processor_id()); |
03e0d461 | 277 | } |
0167c781 | 278 | EXPORT_SYMBOL(touch_softlockup_watchdog); |
58687acb | 279 | |
332fbdbc | 280 | void touch_all_softlockup_watchdogs(void) |
58687acb DZ |
281 | { |
282 | int cpu; | |
283 | ||
284 | /* | |
d57108d4 TG |
285 | * watchdog_mutex cannpt be taken here, as this might be called |
286 | * from (soft)interrupt context, so the access to | |
287 | * watchdog_allowed_cpumask might race with a concurrent update. | |
288 | * | |
289 | * The watchdog time stamp can race against a concurrent real | |
290 | * update as well, the only side effect might be a cycle delay for | |
291 | * the softlockup check. | |
58687acb | 292 | */ |
d57108d4 | 293 | for_each_cpu(cpu, &watchdog_allowed_mask) |
58687acb | 294 | per_cpu(watchdog_touch_ts, cpu) = 0; |
82607adc | 295 | wq_watchdog_touch(-1); |
58687acb DZ |
296 | } |
297 | ||
58687acb DZ |
298 | void touch_softlockup_watchdog_sync(void) |
299 | { | |
f7f66b05 CL |
300 | __this_cpu_write(softlockup_touch_sync, true); |
301 | __this_cpu_write(watchdog_touch_ts, 0); | |
58687acb DZ |
302 | } |
303 | ||
26e09c6e | 304 | static int is_softlockup(unsigned long touch_ts) |
58687acb | 305 | { |
c06b4f19 | 306 | unsigned long now = get_timestamp(); |
58687acb | 307 | |
39d2da21 | 308 | if ((watchdog_enabled & SOFT_WATCHDOG_ENABLED) && watchdog_thresh){ |
195daf66 UO |
309 | /* Warn about unreasonable delays. */ |
310 | if (time_after(now, touch_ts + get_softlockup_thresh())) | |
311 | return now - touch_ts; | |
312 | } | |
58687acb DZ |
313 | return 0; |
314 | } | |
315 | ||
05a4a952 NP |
316 | /* watchdog detector functions */ |
317 | bool is_hardlockup(void) | |
58687acb | 318 | { |
05a4a952 | 319 | unsigned long hrint = __this_cpu_read(hrtimer_interrupts); |
bcd951cf | 320 | |
05a4a952 NP |
321 | if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) |
322 | return true; | |
323 | ||
324 | __this_cpu_write(hrtimer_interrupts_saved, hrint); | |
325 | return false; | |
73ce0511 | 326 | } |
05a4a952 NP |
327 | |
328 | static void watchdog_interrupt_count(void) | |
73ce0511 | 329 | { |
05a4a952 | 330 | __this_cpu_inc(hrtimer_interrupts); |
73ce0511 | 331 | } |
58687acb | 332 | |
be45bf53 PZ |
333 | static DEFINE_PER_CPU(struct completion, softlockup_completion); |
334 | static DEFINE_PER_CPU(struct cpu_stop_work, softlockup_stop_work); | |
335 | ||
9cf57731 PZ |
336 | /* |
337 | * The watchdog thread function - touches the timestamp. | |
338 | * | |
339 | * It only runs once every sample_period seconds (4 seconds by | |
340 | * default) to reset the softlockup timestamp. If this gets delayed | |
341 | * for more than 2*watchdog_thresh seconds then the debug-printout | |
342 | * triggers in watchdog_timer_fn(). | |
343 | */ | |
344 | static int softlockup_fn(void *data) | |
345 | { | |
346 | __this_cpu_write(soft_lockup_hrtimer_cnt, | |
347 | __this_cpu_read(hrtimer_interrupts)); | |
348 | __touch_watchdog(); | |
be45bf53 | 349 | complete(this_cpu_ptr(&softlockup_completion)); |
9cf57731 PZ |
350 | |
351 | return 0; | |
352 | } | |
353 | ||
58687acb DZ |
354 | /* watchdog kicker functions */ |
355 | static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) | |
356 | { | |
909ea964 | 357 | unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts); |
58687acb DZ |
358 | struct pt_regs *regs = get_irq_regs(); |
359 | int duration; | |
ed235875 | 360 | int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; |
58687acb | 361 | |
01f0a027 | 362 | if (!watchdog_enabled) |
b94f5118 DZ |
363 | return HRTIMER_NORESTART; |
364 | ||
58687acb DZ |
365 | /* kick the hardlockup detector */ |
366 | watchdog_interrupt_count(); | |
367 | ||
368 | /* kick the softlockup detector */ | |
be45bf53 PZ |
369 | if (completion_done(this_cpu_ptr(&softlockup_completion))) { |
370 | reinit_completion(this_cpu_ptr(&softlockup_completion)); | |
371 | stop_one_cpu_nowait(smp_processor_id(), | |
372 | softlockup_fn, NULL, | |
373 | this_cpu_ptr(&softlockup_stop_work)); | |
374 | } | |
58687acb DZ |
375 | |
376 | /* .. and repeat */ | |
0f34c400 | 377 | hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period)); |
58687acb DZ |
378 | |
379 | if (touch_ts == 0) { | |
909ea964 | 380 | if (unlikely(__this_cpu_read(softlockup_touch_sync))) { |
58687acb DZ |
381 | /* |
382 | * If the time stamp was touched atomically | |
383 | * make sure the scheduler tick is up to date. | |
384 | */ | |
909ea964 | 385 | __this_cpu_write(softlockup_touch_sync, false); |
58687acb DZ |
386 | sched_clock_tick(); |
387 | } | |
5d1c0f4a EM |
388 | |
389 | /* Clear the guest paused flag on watchdog reset */ | |
390 | kvm_check_and_clear_guest_paused(); | |
58687acb DZ |
391 | __touch_watchdog(); |
392 | return HRTIMER_RESTART; | |
393 | } | |
394 | ||
395 | /* check for a softlockup | |
396 | * This is done by making sure a high priority task is | |
397 | * being scheduled. The task touches the watchdog to | |
398 | * indicate it is getting cpu time. If it hasn't then | |
399 | * this is a good indication some task is hogging the cpu | |
400 | */ | |
26e09c6e | 401 | duration = is_softlockup(touch_ts); |
58687acb | 402 | if (unlikely(duration)) { |
5d1c0f4a EM |
403 | /* |
404 | * If a virtual machine is stopped by the host it can look to | |
405 | * the watchdog like a soft lockup, check to see if the host | |
406 | * stopped the vm before we issue the warning | |
407 | */ | |
408 | if (kvm_check_and_clear_guest_paused()) | |
409 | return HRTIMER_RESTART; | |
410 | ||
58687acb | 411 | /* only warn once */ |
b1a8de1f | 412 | if (__this_cpu_read(soft_watchdog_warn) == true) { |
413 | /* | |
414 | * When multiple processes are causing softlockups the | |
415 | * softlockup detector only warns on the first one | |
416 | * because the code relies on a full quiet cycle to | |
417 | * re-arm. The second process prevents the quiet cycle | |
418 | * and never gets reported. Use task pointers to detect | |
419 | * this. | |
420 | */ | |
421 | if (__this_cpu_read(softlockup_task_ptr_saved) != | |
422 | current) { | |
423 | __this_cpu_write(soft_watchdog_warn, false); | |
424 | __touch_watchdog(); | |
425 | } | |
58687acb | 426 | return HRTIMER_RESTART; |
b1a8de1f | 427 | } |
58687acb | 428 | |
ed235875 AT |
429 | if (softlockup_all_cpu_backtrace) { |
430 | /* Prevent multiple soft-lockup reports if one cpu is already | |
431 | * engaged in dumping cpu back traces | |
432 | */ | |
433 | if (test_and_set_bit(0, &soft_lockup_nmi_warn)) { | |
434 | /* Someone else will report us. Let's give up */ | |
435 | __this_cpu_write(soft_watchdog_warn, true); | |
436 | return HRTIMER_RESTART; | |
437 | } | |
438 | } | |
439 | ||
656c3b79 | 440 | pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", |
26e09c6e | 441 | smp_processor_id(), duration, |
58687acb | 442 | current->comm, task_pid_nr(current)); |
b1a8de1f | 443 | __this_cpu_write(softlockup_task_ptr_saved, current); |
58687acb DZ |
444 | print_modules(); |
445 | print_irqtrace_events(current); | |
446 | if (regs) | |
447 | show_regs(regs); | |
448 | else | |
449 | dump_stack(); | |
450 | ||
ed235875 AT |
451 | if (softlockup_all_cpu_backtrace) { |
452 | /* Avoid generating two back traces for current | |
453 | * given that one is already made above | |
454 | */ | |
455 | trigger_allbutself_cpu_backtrace(); | |
456 | ||
457 | clear_bit(0, &soft_lockup_nmi_warn); | |
458 | /* Barrier to sync with other cpus */ | |
459 | smp_mb__after_atomic(); | |
460 | } | |
461 | ||
69361eef | 462 | add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK); |
58687acb DZ |
463 | if (softlockup_panic) |
464 | panic("softlockup: hung tasks"); | |
909ea964 | 465 | __this_cpu_write(soft_watchdog_warn, true); |
58687acb | 466 | } else |
909ea964 | 467 | __this_cpu_write(soft_watchdog_warn, false); |
58687acb DZ |
468 | |
469 | return HRTIMER_RESTART; | |
470 | } | |
471 | ||
bcd951cf | 472 | static void watchdog_enable(unsigned int cpu) |
58687acb | 473 | { |
01f0a027 | 474 | struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer); |
be45bf53 | 475 | struct completion *done = this_cpu_ptr(&softlockup_completion); |
58687acb | 476 | |
9cf57731 PZ |
477 | WARN_ON_ONCE(cpu != smp_processor_id()); |
478 | ||
be45bf53 PZ |
479 | init_completion(done); |
480 | complete(done); | |
481 | ||
01f0a027 TG |
482 | /* |
483 | * Start the timer first to prevent the NMI watchdog triggering | |
484 | * before the timer has a chance to fire. | |
485 | */ | |
3935e895 BM |
486 | hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
487 | hrtimer->function = watchdog_timer_fn; | |
01f0a027 TG |
488 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
489 | HRTIMER_MODE_REL_PINNED); | |
3935e895 | 490 | |
01f0a027 TG |
491 | /* Initialize timestamp */ |
492 | __touch_watchdog(); | |
bcd951cf | 493 | /* Enable the perf event */ |
146c9d0e TG |
494 | if (watchdog_enabled & NMI_WATCHDOG_ENABLED) |
495 | watchdog_nmi_enable(cpu); | |
bcd951cf | 496 | } |
58687acb | 497 | |
bcd951cf TG |
498 | static void watchdog_disable(unsigned int cpu) |
499 | { | |
01f0a027 | 500 | struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer); |
58687acb | 501 | |
9cf57731 PZ |
502 | WARN_ON_ONCE(cpu != smp_processor_id()); |
503 | ||
01f0a027 TG |
504 | /* |
505 | * Disable the perf event first. That prevents that a large delay | |
506 | * between disabling the timer and disabling the perf event causes | |
507 | * the perf NMI to detect a false positive. | |
508 | */ | |
bcd951cf | 509 | watchdog_nmi_disable(cpu); |
01f0a027 | 510 | hrtimer_cancel(hrtimer); |
be45bf53 | 511 | wait_for_completion(this_cpu_ptr(&softlockup_completion)); |
58687acb DZ |
512 | } |
513 | ||
9cf57731 | 514 | static int softlockup_stop_fn(void *data) |
b8900bc0 | 515 | { |
9cf57731 PZ |
516 | watchdog_disable(smp_processor_id()); |
517 | return 0; | |
b8900bc0 FW |
518 | } |
519 | ||
9cf57731 | 520 | static void softlockup_stop_all(void) |
bcd951cf | 521 | { |
9cf57731 PZ |
522 | int cpu; |
523 | ||
524 | if (!softlockup_initialized) | |
525 | return; | |
526 | ||
527 | for_each_cpu(cpu, &watchdog_allowed_mask) | |
528 | smp_call_on_cpu(cpu, softlockup_stop_fn, NULL, false); | |
529 | ||
530 | cpumask_clear(&watchdog_allowed_mask); | |
bcd951cf TG |
531 | } |
532 | ||
9cf57731 | 533 | static int softlockup_start_fn(void *data) |
bcd951cf | 534 | { |
9cf57731 PZ |
535 | watchdog_enable(smp_processor_id()); |
536 | return 0; | |
bcd951cf | 537 | } |
58687acb | 538 | |
9cf57731 | 539 | static void softlockup_start_all(void) |
2eb2527f | 540 | { |
9cf57731 | 541 | int cpu; |
2eb2527f | 542 | |
9cf57731 PZ |
543 | cpumask_copy(&watchdog_allowed_mask, &watchdog_cpumask); |
544 | for_each_cpu(cpu, &watchdog_allowed_mask) | |
545 | smp_call_on_cpu(cpu, softlockup_start_fn, NULL, false); | |
2eb2527f TG |
546 | } |
547 | ||
9cf57731 | 548 | int lockup_detector_online_cpu(unsigned int cpu) |
2eb2527f | 549 | { |
9cf57731 PZ |
550 | watchdog_enable(cpu); |
551 | return 0; | |
2eb2527f TG |
552 | } |
553 | ||
9cf57731 | 554 | int lockup_detector_offline_cpu(unsigned int cpu) |
2eb2527f | 555 | { |
9cf57731 PZ |
556 | watchdog_disable(cpu); |
557 | return 0; | |
2eb2527f TG |
558 | } |
559 | ||
5587185d | 560 | static void lockup_detector_reconfigure(void) |
2eb2527f | 561 | { |
e31d6883 | 562 | cpus_read_lock(); |
6b9dc480 | 563 | watchdog_nmi_stop(); |
9cf57731 PZ |
564 | |
565 | softlockup_stop_all(); | |
2eb2527f | 566 | set_sample_period(); |
09154985 TG |
567 | lockup_detector_update_enable(); |
568 | if (watchdog_enabled && watchdog_thresh) | |
9cf57731 PZ |
569 | softlockup_start_all(); |
570 | ||
6b9dc480 | 571 | watchdog_nmi_start(); |
e31d6883 TG |
572 | cpus_read_unlock(); |
573 | /* | |
574 | * Must be called outside the cpus locked section to prevent | |
575 | * recursive locking in the perf code. | |
576 | */ | |
577 | __lockup_detector_cleanup(); | |
2eb2527f TG |
578 | } |
579 | ||
580 | /* | |
5587185d | 581 | * Create the watchdog thread infrastructure and configure the detector(s). |
2eb2527f TG |
582 | * |
583 | * The threads are not unparked as watchdog_allowed_mask is empty. When | |
584 | * the threads are sucessfully initialized, take the proper locks and | |
585 | * unpark the threads in the watchdog_cpumask if the watchdog is enabled. | |
586 | */ | |
5587185d | 587 | static __init void lockup_detector_setup(void) |
2eb2527f | 588 | { |
2eb2527f TG |
589 | /* |
590 | * If sysctl is off and watchdog got disabled on the command line, | |
591 | * nothing to do here. | |
592 | */ | |
09154985 TG |
593 | lockup_detector_update_enable(); |
594 | ||
2eb2527f TG |
595 | if (!IS_ENABLED(CONFIG_SYSCTL) && |
596 | !(watchdog_enabled && watchdog_thresh)) | |
597 | return; | |
598 | ||
2eb2527f | 599 | mutex_lock(&watchdog_mutex); |
5587185d | 600 | lockup_detector_reconfigure(); |
9cf57731 | 601 | softlockup_initialized = true; |
2eb2527f TG |
602 | mutex_unlock(&watchdog_mutex); |
603 | } | |
604 | ||
2b9d7f23 | 605 | #else /* CONFIG_SOFTLOCKUP_DETECTOR */ |
5587185d | 606 | static void lockup_detector_reconfigure(void) |
6592ad2f | 607 | { |
e31d6883 | 608 | cpus_read_lock(); |
6b9dc480 | 609 | watchdog_nmi_stop(); |
09154985 | 610 | lockup_detector_update_enable(); |
6b9dc480 | 611 | watchdog_nmi_start(); |
e31d6883 | 612 | cpus_read_unlock(); |
6592ad2f | 613 | } |
5587185d | 614 | static inline void lockup_detector_setup(void) |
34ddaa3e | 615 | { |
5587185d | 616 | lockup_detector_reconfigure(); |
34ddaa3e | 617 | } |
2b9d7f23 | 618 | #endif /* !CONFIG_SOFTLOCKUP_DETECTOR */ |
05a4a952 | 619 | |
941154bd TG |
620 | static void __lockup_detector_cleanup(void) |
621 | { | |
622 | lockdep_assert_held(&watchdog_mutex); | |
623 | hardlockup_detector_perf_cleanup(); | |
624 | } | |
625 | ||
626 | /** | |
627 | * lockup_detector_cleanup - Cleanup after cpu hotplug or sysctl changes | |
628 | * | |
629 | * Caller must not hold the cpu hotplug rwsem. | |
630 | */ | |
631 | void lockup_detector_cleanup(void) | |
632 | { | |
633 | mutex_lock(&watchdog_mutex); | |
634 | __lockup_detector_cleanup(); | |
635 | mutex_unlock(&watchdog_mutex); | |
636 | } | |
637 | ||
6554fd8c TG |
638 | /** |
639 | * lockup_detector_soft_poweroff - Interface to stop lockup detector(s) | |
640 | * | |
641 | * Special interface for parisc. It prevents lockup detector warnings from | |
642 | * the default pm_poweroff() function which busy loops forever. | |
643 | */ | |
644 | void lockup_detector_soft_poweroff(void) | |
645 | { | |
646 | watchdog_enabled = 0; | |
647 | } | |
648 | ||
58cf690a UO |
649 | #ifdef CONFIG_SYSCTL |
650 | ||
e8b62b2d | 651 | /* Propagate any changes to the watchdog threads */ |
d57108d4 | 652 | static void proc_watchdog_update(void) |
a0c9cbb9 | 653 | { |
e8b62b2d TG |
654 | /* Remove impossible cpus to keep sysctl output clean. */ |
655 | cpumask_and(&watchdog_cpumask, &watchdog_cpumask, cpu_possible_mask); | |
5587185d | 656 | lockup_detector_reconfigure(); |
a0c9cbb9 UO |
657 | } |
658 | ||
ef246a21 UO |
659 | /* |
660 | * common function for watchdog, nmi_watchdog and soft_watchdog parameter | |
661 | * | |
7feeb9cd TG |
662 | * caller | table->data points to | 'which' |
663 | * -------------------|----------------------------|-------------------------- | |
664 | * proc_watchdog | watchdog_user_enabled | NMI_WATCHDOG_ENABLED | | |
665 | * | | SOFT_WATCHDOG_ENABLED | |
666 | * -------------------|----------------------------|-------------------------- | |
667 | * proc_nmi_watchdog | nmi_watchdog_user_enabled | NMI_WATCHDOG_ENABLED | |
668 | * -------------------|----------------------------|-------------------------- | |
669 | * proc_soft_watchdog | soft_watchdog_user_enabled | SOFT_WATCHDOG_ENABLED | |
ef246a21 UO |
670 | */ |
671 | static int proc_watchdog_common(int which, struct ctl_table *table, int write, | |
672 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
673 | { | |
09154985 | 674 | int err, old, *param = table->data; |
ef246a21 | 675 | |
946d1977 | 676 | mutex_lock(&watchdog_mutex); |
ef246a21 | 677 | |
ef246a21 | 678 | if (!write) { |
09154985 TG |
679 | /* |
680 | * On read synchronize the userspace interface. This is a | |
681 | * racy snapshot. | |
682 | */ | |
683 | *param = (watchdog_enabled & which) != 0; | |
ef246a21 UO |
684 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
685 | } else { | |
09154985 | 686 | old = READ_ONCE(*param); |
ef246a21 | 687 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
09154985 | 688 | if (!err && old != READ_ONCE(*param)) |
d57108d4 | 689 | proc_watchdog_update(); |
ef246a21 | 690 | } |
946d1977 | 691 | mutex_unlock(&watchdog_mutex); |
ef246a21 UO |
692 | return err; |
693 | } | |
694 | ||
83a80a39 UO |
695 | /* |
696 | * /proc/sys/kernel/watchdog | |
697 | */ | |
698 | int proc_watchdog(struct ctl_table *table, int write, | |
699 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
700 | { | |
701 | return proc_watchdog_common(NMI_WATCHDOG_ENABLED|SOFT_WATCHDOG_ENABLED, | |
702 | table, write, buffer, lenp, ppos); | |
703 | } | |
704 | ||
705 | /* | |
706 | * /proc/sys/kernel/nmi_watchdog | |
58687acb | 707 | */ |
83a80a39 UO |
708 | int proc_nmi_watchdog(struct ctl_table *table, int write, |
709 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
710 | { | |
a994a314 TG |
711 | if (!nmi_watchdog_available && write) |
712 | return -ENOTSUPP; | |
83a80a39 UO |
713 | return proc_watchdog_common(NMI_WATCHDOG_ENABLED, |
714 | table, write, buffer, lenp, ppos); | |
715 | } | |
716 | ||
717 | /* | |
718 | * /proc/sys/kernel/soft_watchdog | |
719 | */ | |
720 | int proc_soft_watchdog(struct ctl_table *table, int write, | |
721 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
722 | { | |
723 | return proc_watchdog_common(SOFT_WATCHDOG_ENABLED, | |
724 | table, write, buffer, lenp, ppos); | |
725 | } | |
58687acb | 726 | |
83a80a39 UO |
727 | /* |
728 | * /proc/sys/kernel/watchdog_thresh | |
729 | */ | |
730 | int proc_watchdog_thresh(struct ctl_table *table, int write, | |
731 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
58687acb | 732 | { |
d57108d4 | 733 | int err, old; |
58687acb | 734 | |
946d1977 | 735 | mutex_lock(&watchdog_mutex); |
bcd951cf | 736 | |
d57108d4 | 737 | old = READ_ONCE(watchdog_thresh); |
b8900bc0 | 738 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
83a80a39 | 739 | |
d57108d4 TG |
740 | if (!err && write && old != READ_ONCE(watchdog_thresh)) |
741 | proc_watchdog_update(); | |
e04ab2bc | 742 | |
946d1977 | 743 | mutex_unlock(&watchdog_mutex); |
b8900bc0 | 744 | return err; |
58687acb | 745 | } |
fe4ba3c3 CM |
746 | |
747 | /* | |
748 | * The cpumask is the mask of possible cpus that the watchdog can run | |
749 | * on, not the mask of cpus it is actually running on. This allows the | |
750 | * user to specify a mask that will include cpus that have not yet | |
751 | * been brought online, if desired. | |
752 | */ | |
753 | int proc_watchdog_cpumask(struct ctl_table *table, int write, | |
754 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
755 | { | |
756 | int err; | |
757 | ||
946d1977 | 758 | mutex_lock(&watchdog_mutex); |
8c073d27 | 759 | |
fe4ba3c3 | 760 | err = proc_do_large_bitmap(table, write, buffer, lenp, ppos); |
05ba3de7 | 761 | if (!err && write) |
e8b62b2d | 762 | proc_watchdog_update(); |
5490125d | 763 | |
946d1977 | 764 | mutex_unlock(&watchdog_mutex); |
fe4ba3c3 CM |
765 | return err; |
766 | } | |
58687acb DZ |
767 | #endif /* CONFIG_SYSCTL */ |
768 | ||
004417a6 | 769 | void __init lockup_detector_init(void) |
58687acb | 770 | { |
13316b31 | 771 | if (tick_nohz_full_enabled()) |
314b08ff | 772 | pr_info("Disabling watchdog on nohz_full cores by default\n"); |
13316b31 | 773 | |
de201559 FW |
774 | cpumask_copy(&watchdog_cpumask, |
775 | housekeeping_cpumask(HK_FLAG_TIMER)); | |
fe4ba3c3 | 776 | |
a994a314 TG |
777 | if (!watchdog_nmi_probe()) |
778 | nmi_watchdog_available = true; | |
5587185d | 779 | lockup_detector_setup(); |
58687acb | 780 | } |