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Commit | Line | Data |
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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 | ||
5f92a7b0 | 12 | #define pr_fmt(fmt) "watchdog: " fmt |
4501980a | 13 | |
58687acb DZ |
14 | #include <linux/mm.h> |
15 | #include <linux/cpu.h> | |
16 | #include <linux/nmi.h> | |
17 | #include <linux/init.h> | |
58687acb DZ |
18 | #include <linux/module.h> |
19 | #include <linux/sysctl.h> | |
bcd951cf | 20 | #include <linux/smpboot.h> |
8bd75c77 | 21 | #include <linux/sched/rt.h> |
ae7e81c0 | 22 | #include <uapi/linux/sched/types.h> |
fe4ba3c3 | 23 | #include <linux/tick.h> |
82607adc | 24 | #include <linux/workqueue.h> |
e6017571 | 25 | #include <linux/sched/clock.h> |
b17b0153 | 26 | #include <linux/sched/debug.h> |
58687acb DZ |
27 | |
28 | #include <asm/irq_regs.h> | |
5d1c0f4a | 29 | #include <linux/kvm_para.h> |
81a4beef | 30 | #include <linux/kthread.h> |
58687acb | 31 | |
946d1977 | 32 | static DEFINE_MUTEX(watchdog_mutex); |
ab992dc3 | 33 | |
05a4a952 | 34 | #if defined(CONFIG_HARDLOCKUP_DETECTOR) || defined(CONFIG_HAVE_NMI_WATCHDOG) |
09154985 TG |
35 | # define WATCHDOG_DEFAULT (SOFT_WATCHDOG_ENABLED | NMI_WATCHDOG_ENABLED) |
36 | # define NMI_WATCHDOG_DEFAULT 1 | |
84d56e66 | 37 | #else |
09154985 TG |
38 | # define WATCHDOG_DEFAULT (SOFT_WATCHDOG_ENABLED) |
39 | # define NMI_WATCHDOG_DEFAULT 0 | |
84d56e66 | 40 | #endif |
05a4a952 | 41 | |
09154985 TG |
42 | unsigned long __read_mostly watchdog_enabled; |
43 | int __read_mostly watchdog_user_enabled = 1; | |
44 | int __read_mostly nmi_watchdog_user_enabled = NMI_WATCHDOG_DEFAULT; | |
45 | int __read_mostly soft_watchdog_user_enabled = 1; | |
7feeb9cd | 46 | int __read_mostly watchdog_thresh = 10; |
a994a314 | 47 | int __read_mostly nmi_watchdog_available; |
7feeb9cd TG |
48 | |
49 | struct cpumask watchdog_allowed_mask __read_mostly; | |
50 | static bool softlockup_threads_initialized __read_mostly; | |
51 | ||
52 | struct cpumask watchdog_cpumask __read_mostly; | |
53 | unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask); | |
54 | ||
05a4a952 | 55 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
05a4a952 NP |
56 | /* |
57 | * Should we panic when a soft-lockup or hard-lockup occurs: | |
58 | */ | |
59 | unsigned int __read_mostly hardlockup_panic = | |
60 | CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE; | |
61 | /* | |
62 | * We may not want to enable hard lockup detection by default in all cases, | |
63 | * for example when running the kernel as a guest on a hypervisor. In these | |
64 | * cases this function can be called to disable hard lockup detection. This | |
65 | * function should only be executed once by the boot processor before the | |
66 | * kernel command line parameters are parsed, because otherwise it is not | |
67 | * possible to override this in hardlockup_panic_setup(). | |
68 | */ | |
7a355820 | 69 | void __init hardlockup_detector_disable(void) |
05a4a952 | 70 | { |
09154985 | 71 | nmi_watchdog_user_enabled = 0; |
05a4a952 NP |
72 | } |
73 | ||
74 | static int __init hardlockup_panic_setup(char *str) | |
75 | { | |
76 | if (!strncmp(str, "panic", 5)) | |
77 | hardlockup_panic = 1; | |
78 | else if (!strncmp(str, "nopanic", 7)) | |
79 | hardlockup_panic = 0; | |
80 | else if (!strncmp(str, "0", 1)) | |
09154985 | 81 | nmi_watchdog_user_enabled = 0; |
05a4a952 | 82 | else if (!strncmp(str, "1", 1)) |
09154985 | 83 | nmi_watchdog_user_enabled = 1; |
05a4a952 NP |
84 | return 1; |
85 | } | |
86 | __setup("nmi_watchdog=", hardlockup_panic_setup); | |
87 | ||
368a7e2c TG |
88 | # ifdef CONFIG_SMP |
89 | int __read_mostly sysctl_hardlockup_all_cpu_backtrace; | |
05a4a952 | 90 | |
368a7e2c TG |
91 | static int __init hardlockup_all_cpu_backtrace_setup(char *str) |
92 | { | |
93 | sysctl_hardlockup_all_cpu_backtrace = !!simple_strtol(str, NULL, 0); | |
94 | return 1; | |
95 | } | |
96 | __setup("hardlockup_all_cpu_backtrace=", hardlockup_all_cpu_backtrace_setup); | |
97 | # endif /* CONFIG_SMP */ | |
98 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ | |
05a4a952 | 99 | |
05a4a952 NP |
100 | /* |
101 | * These functions can be overridden if an architecture implements its | |
102 | * own hardlockup detector. | |
a10a842f NP |
103 | * |
104 | * watchdog_nmi_enable/disable can be implemented to start and stop when | |
105 | * softlockup watchdog threads start and stop. The arch must select the | |
106 | * SOFTLOCKUP_DETECTOR Kconfig. | |
05a4a952 NP |
107 | */ |
108 | int __weak watchdog_nmi_enable(unsigned int cpu) | |
109 | { | |
110 | return 0; | |
111 | } | |
941154bd | 112 | |
05a4a952 NP |
113 | void __weak watchdog_nmi_disable(unsigned int cpu) |
114 | { | |
941154bd | 115 | hardlockup_detector_perf_disable(); |
05a4a952 NP |
116 | } |
117 | ||
a994a314 TG |
118 | /* Return 0, if a NMI watchdog is available. Error code otherwise */ |
119 | int __weak __init watchdog_nmi_probe(void) | |
120 | { | |
121 | return hardlockup_detector_perf_init(); | |
122 | } | |
123 | ||
6592ad2f TG |
124 | /** |
125 | * watchdog_nmi_reconfigure - Optional function to reconfigure NMI watchdogs | |
126 | * @run: If false stop the watchdogs on all enabled CPUs | |
127 | * If true start the watchdogs on all enabled CPUs | |
128 | * | |
129 | * The core call order is: | |
130 | * watchdog_nmi_reconfigure(false); | |
131 | * update_variables(); | |
132 | * watchdog_nmi_reconfigure(true); | |
133 | * | |
134 | * The second call which starts the watchdogs again guarantees that the | |
135 | * following variables are stable across the call. | |
7feeb9cd | 136 | * - watchdog_enabled |
a10a842f NP |
137 | * - watchdog_thresh |
138 | * - watchdog_cpumask | |
6592ad2f TG |
139 | * |
140 | * After the call the variables can be changed again. | |
a10a842f | 141 | */ |
6592ad2f | 142 | void __weak watchdog_nmi_reconfigure(bool run) { } |
a10a842f | 143 | |
09154985 TG |
144 | /** |
145 | * lockup_detector_update_enable - Update the sysctl enable bit | |
146 | * | |
147 | * Caller needs to make sure that the NMI/perf watchdogs are off, so this | |
148 | * can't race with watchdog_nmi_disable(). | |
149 | */ | |
150 | static void lockup_detector_update_enable(void) | |
151 | { | |
152 | watchdog_enabled = 0; | |
153 | if (!watchdog_user_enabled) | |
154 | return; | |
a994a314 | 155 | if (nmi_watchdog_available && nmi_watchdog_user_enabled) |
09154985 TG |
156 | watchdog_enabled |= NMI_WATCHDOG_ENABLED; |
157 | if (soft_watchdog_user_enabled) | |
158 | watchdog_enabled |= SOFT_WATCHDOG_ENABLED; | |
159 | } | |
160 | ||
05a4a952 NP |
161 | #ifdef CONFIG_SOFTLOCKUP_DETECTOR |
162 | ||
2b9d7f23 TG |
163 | /* Global variables, exported for sysctl */ |
164 | unsigned int __read_mostly softlockup_panic = | |
165 | CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE; | |
2eb2527f | 166 | |
0f34c400 | 167 | static u64 __read_mostly sample_period; |
58687acb DZ |
168 | |
169 | static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); | |
170 | static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog); | |
171 | static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer); | |
172 | static DEFINE_PER_CPU(bool, softlockup_touch_sync); | |
58687acb | 173 | static DEFINE_PER_CPU(bool, soft_watchdog_warn); |
bcd951cf TG |
174 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); |
175 | static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt); | |
b1a8de1f | 176 | static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved); |
58687acb | 177 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); |
ed235875 | 178 | static unsigned long soft_lockup_nmi_warn; |
58687acb | 179 | |
58687acb DZ |
180 | static int __init softlockup_panic_setup(char *str) |
181 | { | |
182 | softlockup_panic = simple_strtoul(str, NULL, 0); | |
58687acb DZ |
183 | return 1; |
184 | } | |
185 | __setup("softlockup_panic=", softlockup_panic_setup); | |
186 | ||
187 | static int __init nowatchdog_setup(char *str) | |
188 | { | |
09154985 | 189 | watchdog_user_enabled = 0; |
58687acb DZ |
190 | return 1; |
191 | } | |
192 | __setup("nowatchdog", nowatchdog_setup); | |
193 | ||
58687acb DZ |
194 | static int __init nosoftlockup_setup(char *str) |
195 | { | |
09154985 | 196 | soft_watchdog_user_enabled = 0; |
58687acb DZ |
197 | return 1; |
198 | } | |
199 | __setup("nosoftlockup", nosoftlockup_setup); | |
195daf66 | 200 | |
ed235875 | 201 | #ifdef CONFIG_SMP |
368a7e2c TG |
202 | int __read_mostly sysctl_softlockup_all_cpu_backtrace; |
203 | ||
ed235875 AT |
204 | static int __init softlockup_all_cpu_backtrace_setup(char *str) |
205 | { | |
368a7e2c | 206 | sysctl_softlockup_all_cpu_backtrace = !!simple_strtol(str, NULL, 0); |
ed235875 AT |
207 | return 1; |
208 | } | |
209 | __setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup); | |
05a4a952 | 210 | #endif |
58687acb | 211 | |
941154bd TG |
212 | static void __lockup_detector_cleanup(void); |
213 | ||
4eec42f3 MSB |
214 | /* |
215 | * Hard-lockup warnings should be triggered after just a few seconds. Soft- | |
216 | * lockups can have false positives under extreme conditions. So we generally | |
217 | * want a higher threshold for soft lockups than for hard lockups. So we couple | |
218 | * the thresholds with a factor: we make the soft threshold twice the amount of | |
219 | * time the hard threshold is. | |
220 | */ | |
6e9101ae | 221 | static int get_softlockup_thresh(void) |
4eec42f3 MSB |
222 | { |
223 | return watchdog_thresh * 2; | |
224 | } | |
58687acb DZ |
225 | |
226 | /* | |
227 | * Returns seconds, approximately. We don't need nanosecond | |
228 | * resolution, and we don't need to waste time with a big divide when | |
229 | * 2^30ns == 1.074s. | |
230 | */ | |
c06b4f19 | 231 | static unsigned long get_timestamp(void) |
58687acb | 232 | { |
545a2bf7 | 233 | return running_clock() >> 30LL; /* 2^30 ~= 10^9 */ |
58687acb DZ |
234 | } |
235 | ||
0f34c400 | 236 | static void set_sample_period(void) |
58687acb DZ |
237 | { |
238 | /* | |
586692a5 | 239 | * convert watchdog_thresh from seconds to ns |
86f5e6a7 FLVC |
240 | * the divide by 5 is to give hrtimer several chances (two |
241 | * or three with the current relation between the soft | |
242 | * and hard thresholds) to increment before the | |
243 | * hardlockup detector generates a warning | |
58687acb | 244 | */ |
0f34c400 | 245 | sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); |
7edaeb68 | 246 | watchdog_update_hrtimer_threshold(sample_period); |
58687acb DZ |
247 | } |
248 | ||
249 | /* Commands for resetting the watchdog */ | |
250 | static void __touch_watchdog(void) | |
251 | { | |
c06b4f19 | 252 | __this_cpu_write(watchdog_touch_ts, get_timestamp()); |
58687acb DZ |
253 | } |
254 | ||
03e0d461 TH |
255 | /** |
256 | * touch_softlockup_watchdog_sched - touch watchdog on scheduler stalls | |
257 | * | |
258 | * Call when the scheduler may have stalled for legitimate reasons | |
259 | * preventing the watchdog task from executing - e.g. the scheduler | |
260 | * entering idle state. This should only be used for scheduler events. | |
261 | * Use touch_softlockup_watchdog() for everything else. | |
262 | */ | |
263 | void touch_softlockup_watchdog_sched(void) | |
58687acb | 264 | { |
7861144b AM |
265 | /* |
266 | * Preemption can be enabled. It doesn't matter which CPU's timestamp | |
267 | * gets zeroed here, so use the raw_ operation. | |
268 | */ | |
269 | raw_cpu_write(watchdog_touch_ts, 0); | |
58687acb | 270 | } |
03e0d461 TH |
271 | |
272 | void touch_softlockup_watchdog(void) | |
273 | { | |
274 | touch_softlockup_watchdog_sched(); | |
82607adc | 275 | wq_watchdog_touch(raw_smp_processor_id()); |
03e0d461 | 276 | } |
0167c781 | 277 | EXPORT_SYMBOL(touch_softlockup_watchdog); |
58687acb | 278 | |
332fbdbc | 279 | void touch_all_softlockup_watchdogs(void) |
58687acb DZ |
280 | { |
281 | int cpu; | |
282 | ||
283 | /* | |
d57108d4 TG |
284 | * watchdog_mutex cannpt be taken here, as this might be called |
285 | * from (soft)interrupt context, so the access to | |
286 | * watchdog_allowed_cpumask might race with a concurrent update. | |
287 | * | |
288 | * The watchdog time stamp can race against a concurrent real | |
289 | * update as well, the only side effect might be a cycle delay for | |
290 | * the softlockup check. | |
58687acb | 291 | */ |
d57108d4 | 292 | for_each_cpu(cpu, &watchdog_allowed_mask) |
58687acb | 293 | per_cpu(watchdog_touch_ts, cpu) = 0; |
82607adc | 294 | wq_watchdog_touch(-1); |
58687acb DZ |
295 | } |
296 | ||
58687acb DZ |
297 | void touch_softlockup_watchdog_sync(void) |
298 | { | |
f7f66b05 CL |
299 | __this_cpu_write(softlockup_touch_sync, true); |
300 | __this_cpu_write(watchdog_touch_ts, 0); | |
58687acb DZ |
301 | } |
302 | ||
26e09c6e | 303 | static int is_softlockup(unsigned long touch_ts) |
58687acb | 304 | { |
c06b4f19 | 305 | unsigned long now = get_timestamp(); |
58687acb | 306 | |
39d2da21 | 307 | if ((watchdog_enabled & SOFT_WATCHDOG_ENABLED) && watchdog_thresh){ |
195daf66 UO |
308 | /* Warn about unreasonable delays. */ |
309 | if (time_after(now, touch_ts + get_softlockup_thresh())) | |
310 | return now - touch_ts; | |
311 | } | |
58687acb DZ |
312 | return 0; |
313 | } | |
314 | ||
05a4a952 NP |
315 | /* watchdog detector functions */ |
316 | bool is_hardlockup(void) | |
58687acb | 317 | { |
05a4a952 | 318 | unsigned long hrint = __this_cpu_read(hrtimer_interrupts); |
bcd951cf | 319 | |
05a4a952 NP |
320 | if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) |
321 | return true; | |
322 | ||
323 | __this_cpu_write(hrtimer_interrupts_saved, hrint); | |
324 | return false; | |
73ce0511 | 325 | } |
05a4a952 NP |
326 | |
327 | static void watchdog_interrupt_count(void) | |
73ce0511 | 328 | { |
05a4a952 | 329 | __this_cpu_inc(hrtimer_interrupts); |
73ce0511 | 330 | } |
58687acb DZ |
331 | |
332 | /* watchdog kicker functions */ | |
333 | static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) | |
334 | { | |
909ea964 | 335 | unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts); |
58687acb DZ |
336 | struct pt_regs *regs = get_irq_regs(); |
337 | int duration; | |
ed235875 | 338 | int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; |
58687acb | 339 | |
01f0a027 | 340 | if (!watchdog_enabled) |
b94f5118 DZ |
341 | return HRTIMER_NORESTART; |
342 | ||
58687acb DZ |
343 | /* kick the hardlockup detector */ |
344 | watchdog_interrupt_count(); | |
345 | ||
346 | /* kick the softlockup detector */ | |
909ea964 | 347 | wake_up_process(__this_cpu_read(softlockup_watchdog)); |
58687acb DZ |
348 | |
349 | /* .. and repeat */ | |
0f34c400 | 350 | hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period)); |
58687acb DZ |
351 | |
352 | if (touch_ts == 0) { | |
909ea964 | 353 | if (unlikely(__this_cpu_read(softlockup_touch_sync))) { |
58687acb DZ |
354 | /* |
355 | * If the time stamp was touched atomically | |
356 | * make sure the scheduler tick is up to date. | |
357 | */ | |
909ea964 | 358 | __this_cpu_write(softlockup_touch_sync, false); |
58687acb DZ |
359 | sched_clock_tick(); |
360 | } | |
5d1c0f4a EM |
361 | |
362 | /* Clear the guest paused flag on watchdog reset */ | |
363 | kvm_check_and_clear_guest_paused(); | |
58687acb DZ |
364 | __touch_watchdog(); |
365 | return HRTIMER_RESTART; | |
366 | } | |
367 | ||
368 | /* check for a softlockup | |
369 | * This is done by making sure a high priority task is | |
370 | * being scheduled. The task touches the watchdog to | |
371 | * indicate it is getting cpu time. If it hasn't then | |
372 | * this is a good indication some task is hogging the cpu | |
373 | */ | |
26e09c6e | 374 | duration = is_softlockup(touch_ts); |
58687acb | 375 | if (unlikely(duration)) { |
5d1c0f4a EM |
376 | /* |
377 | * If a virtual machine is stopped by the host it can look to | |
378 | * the watchdog like a soft lockup, check to see if the host | |
379 | * stopped the vm before we issue the warning | |
380 | */ | |
381 | if (kvm_check_and_clear_guest_paused()) | |
382 | return HRTIMER_RESTART; | |
383 | ||
58687acb | 384 | /* only warn once */ |
b1a8de1f | 385 | if (__this_cpu_read(soft_watchdog_warn) == true) { |
386 | /* | |
387 | * When multiple processes are causing softlockups the | |
388 | * softlockup detector only warns on the first one | |
389 | * because the code relies on a full quiet cycle to | |
390 | * re-arm. The second process prevents the quiet cycle | |
391 | * and never gets reported. Use task pointers to detect | |
392 | * this. | |
393 | */ | |
394 | if (__this_cpu_read(softlockup_task_ptr_saved) != | |
395 | current) { | |
396 | __this_cpu_write(soft_watchdog_warn, false); | |
397 | __touch_watchdog(); | |
398 | } | |
58687acb | 399 | return HRTIMER_RESTART; |
b1a8de1f | 400 | } |
58687acb | 401 | |
ed235875 AT |
402 | if (softlockup_all_cpu_backtrace) { |
403 | /* Prevent multiple soft-lockup reports if one cpu is already | |
404 | * engaged in dumping cpu back traces | |
405 | */ | |
406 | if (test_and_set_bit(0, &soft_lockup_nmi_warn)) { | |
407 | /* Someone else will report us. Let's give up */ | |
408 | __this_cpu_write(soft_watchdog_warn, true); | |
409 | return HRTIMER_RESTART; | |
410 | } | |
411 | } | |
412 | ||
656c3b79 | 413 | pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", |
26e09c6e | 414 | smp_processor_id(), duration, |
58687acb | 415 | current->comm, task_pid_nr(current)); |
b1a8de1f | 416 | __this_cpu_write(softlockup_task_ptr_saved, current); |
58687acb DZ |
417 | print_modules(); |
418 | print_irqtrace_events(current); | |
419 | if (regs) | |
420 | show_regs(regs); | |
421 | else | |
422 | dump_stack(); | |
423 | ||
ed235875 AT |
424 | if (softlockup_all_cpu_backtrace) { |
425 | /* Avoid generating two back traces for current | |
426 | * given that one is already made above | |
427 | */ | |
428 | trigger_allbutself_cpu_backtrace(); | |
429 | ||
430 | clear_bit(0, &soft_lockup_nmi_warn); | |
431 | /* Barrier to sync with other cpus */ | |
432 | smp_mb__after_atomic(); | |
433 | } | |
434 | ||
69361eef | 435 | add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK); |
58687acb DZ |
436 | if (softlockup_panic) |
437 | panic("softlockup: hung tasks"); | |
909ea964 | 438 | __this_cpu_write(soft_watchdog_warn, true); |
58687acb | 439 | } else |
909ea964 | 440 | __this_cpu_write(soft_watchdog_warn, false); |
58687acb DZ |
441 | |
442 | return HRTIMER_RESTART; | |
443 | } | |
444 | ||
bcd951cf TG |
445 | static void watchdog_set_prio(unsigned int policy, unsigned int prio) |
446 | { | |
447 | struct sched_param param = { .sched_priority = prio }; | |
58687acb | 448 | |
bcd951cf TG |
449 | sched_setscheduler(current, policy, ¶m); |
450 | } | |
451 | ||
452 | static void watchdog_enable(unsigned int cpu) | |
58687acb | 453 | { |
01f0a027 | 454 | struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer); |
58687acb | 455 | |
01f0a027 TG |
456 | /* |
457 | * Start the timer first to prevent the NMI watchdog triggering | |
458 | * before the timer has a chance to fire. | |
459 | */ | |
3935e895 BM |
460 | hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
461 | hrtimer->function = watchdog_timer_fn; | |
01f0a027 TG |
462 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
463 | HRTIMER_MODE_REL_PINNED); | |
3935e895 | 464 | |
01f0a027 TG |
465 | /* Initialize timestamp */ |
466 | __touch_watchdog(); | |
bcd951cf TG |
467 | /* Enable the perf event */ |
468 | watchdog_nmi_enable(cpu); | |
58687acb | 469 | |
bcd951cf | 470 | watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1); |
bcd951cf | 471 | } |
58687acb | 472 | |
bcd951cf TG |
473 | static void watchdog_disable(unsigned int cpu) |
474 | { | |
01f0a027 | 475 | struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer); |
58687acb | 476 | |
bcd951cf | 477 | watchdog_set_prio(SCHED_NORMAL, 0); |
01f0a027 TG |
478 | /* |
479 | * Disable the perf event first. That prevents that a large delay | |
480 | * between disabling the timer and disabling the perf event causes | |
481 | * the perf NMI to detect a false positive. | |
482 | */ | |
bcd951cf | 483 | watchdog_nmi_disable(cpu); |
01f0a027 | 484 | hrtimer_cancel(hrtimer); |
58687acb DZ |
485 | } |
486 | ||
b8900bc0 FW |
487 | static void watchdog_cleanup(unsigned int cpu, bool online) |
488 | { | |
489 | watchdog_disable(cpu); | |
490 | } | |
491 | ||
bcd951cf TG |
492 | static int watchdog_should_run(unsigned int cpu) |
493 | { | |
494 | return __this_cpu_read(hrtimer_interrupts) != | |
495 | __this_cpu_read(soft_lockup_hrtimer_cnt); | |
496 | } | |
497 | ||
498 | /* | |
499 | * The watchdog thread function - touches the timestamp. | |
500 | * | |
0f34c400 | 501 | * It only runs once every sample_period seconds (4 seconds by |
bcd951cf TG |
502 | * default) to reset the softlockup timestamp. If this gets delayed |
503 | * for more than 2*watchdog_thresh seconds then the debug-printout | |
504 | * triggers in watchdog_timer_fn(). | |
505 | */ | |
506 | static void watchdog(unsigned int cpu) | |
507 | { | |
508 | __this_cpu_write(soft_lockup_hrtimer_cnt, | |
509 | __this_cpu_read(hrtimer_interrupts)); | |
510 | __touch_watchdog(); | |
511 | } | |
58687acb | 512 | |
b8900bc0 FW |
513 | static struct smp_hotplug_thread watchdog_threads = { |
514 | .store = &softlockup_watchdog, | |
515 | .thread_should_run = watchdog_should_run, | |
516 | .thread_fn = watchdog, | |
517 | .thread_comm = "watchdog/%u", | |
518 | .setup = watchdog_enable, | |
519 | .cleanup = watchdog_cleanup, | |
520 | .park = watchdog_disable, | |
521 | .unpark = watchdog_enable, | |
522 | }; | |
523 | ||
2eb2527f TG |
524 | static void softlockup_update_smpboot_threads(void) |
525 | { | |
526 | lockdep_assert_held(&watchdog_mutex); | |
527 | ||
528 | if (!softlockup_threads_initialized) | |
529 | return; | |
530 | ||
531 | smpboot_update_cpumask_percpu_thread(&watchdog_threads, | |
532 | &watchdog_allowed_mask); | |
533 | __lockup_detector_cleanup(); | |
534 | } | |
535 | ||
536 | /* Temporarily park all watchdog threads */ | |
537 | static void softlockup_park_all_threads(void) | |
538 | { | |
539 | cpumask_clear(&watchdog_allowed_mask); | |
540 | softlockup_update_smpboot_threads(); | |
541 | } | |
542 | ||
e8b62b2d TG |
543 | /* Unpark enabled threads */ |
544 | static void softlockup_unpark_threads(void) | |
2eb2527f TG |
545 | { |
546 | cpumask_copy(&watchdog_allowed_mask, &watchdog_cpumask); | |
547 | softlockup_update_smpboot_threads(); | |
548 | } | |
549 | ||
09154985 | 550 | static void softlockup_reconfigure_threads(void) |
2eb2527f | 551 | { |
6592ad2f | 552 | watchdog_nmi_reconfigure(false); |
2eb2527f TG |
553 | softlockup_park_all_threads(); |
554 | set_sample_period(); | |
09154985 TG |
555 | lockup_detector_update_enable(); |
556 | if (watchdog_enabled && watchdog_thresh) | |
e8b62b2d | 557 | softlockup_unpark_threads(); |
6592ad2f | 558 | watchdog_nmi_reconfigure(true); |
2eb2527f TG |
559 | } |
560 | ||
561 | /* | |
562 | * Create the watchdog thread infrastructure. | |
563 | * | |
564 | * The threads are not unparked as watchdog_allowed_mask is empty. When | |
565 | * the threads are sucessfully initialized, take the proper locks and | |
566 | * unpark the threads in the watchdog_cpumask if the watchdog is enabled. | |
567 | */ | |
568 | static __init void softlockup_init_threads(void) | |
569 | { | |
570 | int ret; | |
571 | ||
572 | /* | |
573 | * If sysctl is off and watchdog got disabled on the command line, | |
574 | * nothing to do here. | |
575 | */ | |
09154985 TG |
576 | lockup_detector_update_enable(); |
577 | ||
2eb2527f TG |
578 | if (!IS_ENABLED(CONFIG_SYSCTL) && |
579 | !(watchdog_enabled && watchdog_thresh)) | |
580 | return; | |
581 | ||
582 | ret = smpboot_register_percpu_thread_cpumask(&watchdog_threads, | |
583 | &watchdog_allowed_mask); | |
584 | if (ret) { | |
585 | pr_err("Failed to initialize soft lockup detector threads\n"); | |
586 | return; | |
587 | } | |
588 | ||
589 | mutex_lock(&watchdog_mutex); | |
590 | softlockup_threads_initialized = true; | |
09154985 | 591 | softlockup_reconfigure_threads(); |
2eb2527f TG |
592 | mutex_unlock(&watchdog_mutex); |
593 | } | |
594 | ||
2b9d7f23 TG |
595 | #else /* CONFIG_SOFTLOCKUP_DETECTOR */ |
596 | static inline int watchdog_park_threads(void) { return 0; } | |
597 | static inline void watchdog_unpark_threads(void) { } | |
598 | static inline int watchdog_enable_all_cpus(void) { return 0; } | |
599 | static inline void watchdog_disable_all_cpus(void) { } | |
2eb2527f | 600 | static inline void softlockup_init_threads(void) { } |
09154985 | 601 | static void softlockup_reconfigure_threads(void) |
6592ad2f TG |
602 | { |
603 | watchdog_nmi_reconfigure(false); | |
09154985 | 604 | lockup_detector_update_enable(); |
6592ad2f TG |
605 | watchdog_nmi_reconfigure(true); |
606 | } | |
2b9d7f23 | 607 | #endif /* !CONFIG_SOFTLOCKUP_DETECTOR */ |
05a4a952 | 608 | |
941154bd TG |
609 | static void __lockup_detector_cleanup(void) |
610 | { | |
611 | lockdep_assert_held(&watchdog_mutex); | |
612 | hardlockup_detector_perf_cleanup(); | |
613 | } | |
614 | ||
615 | /** | |
616 | * lockup_detector_cleanup - Cleanup after cpu hotplug or sysctl changes | |
617 | * | |
618 | * Caller must not hold the cpu hotplug rwsem. | |
619 | */ | |
620 | void lockup_detector_cleanup(void) | |
621 | { | |
622 | mutex_lock(&watchdog_mutex); | |
623 | __lockup_detector_cleanup(); | |
624 | mutex_unlock(&watchdog_mutex); | |
625 | } | |
626 | ||
6554fd8c TG |
627 | /** |
628 | * lockup_detector_soft_poweroff - Interface to stop lockup detector(s) | |
629 | * | |
630 | * Special interface for parisc. It prevents lockup detector warnings from | |
631 | * the default pm_poweroff() function which busy loops forever. | |
632 | */ | |
633 | void lockup_detector_soft_poweroff(void) | |
634 | { | |
635 | watchdog_enabled = 0; | |
636 | } | |
637 | ||
58cf690a UO |
638 | #ifdef CONFIG_SYSCTL |
639 | ||
e8b62b2d | 640 | /* Propagate any changes to the watchdog threads */ |
d57108d4 | 641 | static void proc_watchdog_update(void) |
a0c9cbb9 | 642 | { |
e8b62b2d TG |
643 | /* Remove impossible cpus to keep sysctl output clean. */ |
644 | cpumask_and(&watchdog_cpumask, &watchdog_cpumask, cpu_possible_mask); | |
09154985 | 645 | softlockup_reconfigure_threads(); |
a0c9cbb9 UO |
646 | } |
647 | ||
ef246a21 UO |
648 | /* |
649 | * common function for watchdog, nmi_watchdog and soft_watchdog parameter | |
650 | * | |
7feeb9cd TG |
651 | * caller | table->data points to | 'which' |
652 | * -------------------|----------------------------|-------------------------- | |
653 | * proc_watchdog | watchdog_user_enabled | NMI_WATCHDOG_ENABLED | | |
654 | * | | SOFT_WATCHDOG_ENABLED | |
655 | * -------------------|----------------------------|-------------------------- | |
656 | * proc_nmi_watchdog | nmi_watchdog_user_enabled | NMI_WATCHDOG_ENABLED | |
657 | * -------------------|----------------------------|-------------------------- | |
658 | * proc_soft_watchdog | soft_watchdog_user_enabled | SOFT_WATCHDOG_ENABLED | |
ef246a21 UO |
659 | */ |
660 | static int proc_watchdog_common(int which, struct ctl_table *table, int write, | |
661 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
662 | { | |
09154985 | 663 | int err, old, *param = table->data; |
ef246a21 | 664 | |
b7a34981 | 665 | cpu_hotplug_disable(); |
946d1977 | 666 | mutex_lock(&watchdog_mutex); |
ef246a21 | 667 | |
ef246a21 | 668 | if (!write) { |
09154985 TG |
669 | /* |
670 | * On read synchronize the userspace interface. This is a | |
671 | * racy snapshot. | |
672 | */ | |
673 | *param = (watchdog_enabled & which) != 0; | |
ef246a21 UO |
674 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
675 | } else { | |
09154985 | 676 | old = READ_ONCE(*param); |
ef246a21 | 677 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
09154985 | 678 | if (!err && old != READ_ONCE(*param)) |
d57108d4 | 679 | proc_watchdog_update(); |
ef246a21 | 680 | } |
946d1977 | 681 | mutex_unlock(&watchdog_mutex); |
b7a34981 | 682 | cpu_hotplug_enable(); |
ef246a21 UO |
683 | return err; |
684 | } | |
685 | ||
83a80a39 UO |
686 | /* |
687 | * /proc/sys/kernel/watchdog | |
688 | */ | |
689 | int proc_watchdog(struct ctl_table *table, int write, | |
690 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
691 | { | |
692 | return proc_watchdog_common(NMI_WATCHDOG_ENABLED|SOFT_WATCHDOG_ENABLED, | |
693 | table, write, buffer, lenp, ppos); | |
694 | } | |
695 | ||
696 | /* | |
697 | * /proc/sys/kernel/nmi_watchdog | |
58687acb | 698 | */ |
83a80a39 UO |
699 | int proc_nmi_watchdog(struct ctl_table *table, int write, |
700 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
701 | { | |
a994a314 TG |
702 | if (!nmi_watchdog_available && write) |
703 | return -ENOTSUPP; | |
83a80a39 UO |
704 | return proc_watchdog_common(NMI_WATCHDOG_ENABLED, |
705 | table, write, buffer, lenp, ppos); | |
706 | } | |
707 | ||
708 | /* | |
709 | * /proc/sys/kernel/soft_watchdog | |
710 | */ | |
711 | int proc_soft_watchdog(struct ctl_table *table, int write, | |
712 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
713 | { | |
714 | return proc_watchdog_common(SOFT_WATCHDOG_ENABLED, | |
715 | table, write, buffer, lenp, ppos); | |
716 | } | |
58687acb | 717 | |
83a80a39 UO |
718 | /* |
719 | * /proc/sys/kernel/watchdog_thresh | |
720 | */ | |
721 | int proc_watchdog_thresh(struct ctl_table *table, int write, | |
722 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
58687acb | 723 | { |
d57108d4 | 724 | int err, old; |
58687acb | 725 | |
b7a34981 | 726 | cpu_hotplug_disable(); |
946d1977 | 727 | mutex_lock(&watchdog_mutex); |
bcd951cf | 728 | |
d57108d4 | 729 | old = READ_ONCE(watchdog_thresh); |
b8900bc0 | 730 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
83a80a39 | 731 | |
d57108d4 TG |
732 | if (!err && write && old != READ_ONCE(watchdog_thresh)) |
733 | proc_watchdog_update(); | |
e04ab2bc | 734 | |
946d1977 | 735 | mutex_unlock(&watchdog_mutex); |
b7a34981 | 736 | cpu_hotplug_enable(); |
b8900bc0 | 737 | return err; |
58687acb | 738 | } |
fe4ba3c3 CM |
739 | |
740 | /* | |
741 | * The cpumask is the mask of possible cpus that the watchdog can run | |
742 | * on, not the mask of cpus it is actually running on. This allows the | |
743 | * user to specify a mask that will include cpus that have not yet | |
744 | * been brought online, if desired. | |
745 | */ | |
746 | int proc_watchdog_cpumask(struct ctl_table *table, int write, | |
747 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
748 | { | |
749 | int err; | |
750 | ||
b7a34981 | 751 | cpu_hotplug_disable(); |
946d1977 | 752 | mutex_lock(&watchdog_mutex); |
8c073d27 | 753 | |
fe4ba3c3 | 754 | err = proc_do_large_bitmap(table, write, buffer, lenp, ppos); |
05ba3de7 | 755 | if (!err && write) |
e8b62b2d | 756 | proc_watchdog_update(); |
5490125d | 757 | |
946d1977 | 758 | mutex_unlock(&watchdog_mutex); |
b7a34981 | 759 | cpu_hotplug_enable(); |
fe4ba3c3 CM |
760 | return err; |
761 | } | |
58687acb DZ |
762 | #endif /* CONFIG_SYSCTL */ |
763 | ||
004417a6 | 764 | void __init lockup_detector_init(void) |
58687acb | 765 | { |
fe4ba3c3 CM |
766 | #ifdef CONFIG_NO_HZ_FULL |
767 | if (tick_nohz_full_enabled()) { | |
314b08ff FW |
768 | pr_info("Disabling watchdog on nohz_full cores by default\n"); |
769 | cpumask_copy(&watchdog_cpumask, housekeeping_mask); | |
fe4ba3c3 CM |
770 | } else |
771 | cpumask_copy(&watchdog_cpumask, cpu_possible_mask); | |
772 | #else | |
773 | cpumask_copy(&watchdog_cpumask, cpu_possible_mask); | |
774 | #endif | |
775 | ||
a994a314 TG |
776 | if (!watchdog_nmi_probe()) |
777 | nmi_watchdog_available = true; | |
d57108d4 | 778 | softlockup_init_threads(); |
58687acb | 779 | } |