Commit | Line | Data |
---|---|---|
58687acb DZ |
1 | /* |
2 | * Detect hard and soft lockups on a system | |
3 | * | |
4 | * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc. | |
5 | * | |
86f5e6a7 FLVC |
6 | * Note: Most of this code is borrowed heavily from the original softlockup |
7 | * detector, so thanks to Ingo for the initial implementation. | |
8 | * Some chunks also taken from the old x86-specific nmi watchdog code, thanks | |
58687acb DZ |
9 | * to those contributors as well. |
10 | */ | |
11 | ||
4501980a AM |
12 | #define pr_fmt(fmt) "NMI watchdog: " fmt |
13 | ||
58687acb DZ |
14 | #include <linux/mm.h> |
15 | #include <linux/cpu.h> | |
16 | #include <linux/nmi.h> | |
17 | #include <linux/init.h> | |
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> |
fe4ba3c3 | 22 | #include <linux/tick.h> |
58687acb DZ |
23 | |
24 | #include <asm/irq_regs.h> | |
5d1c0f4a | 25 | #include <linux/kvm_para.h> |
58687acb | 26 | #include <linux/perf_event.h> |
81a4beef | 27 | #include <linux/kthread.h> |
58687acb | 28 | |
84d56e66 UO |
29 | /* |
30 | * The run state of the lockup detectors is controlled by the content of the | |
31 | * 'watchdog_enabled' variable. Each lockup detector has its dedicated bit - | |
32 | * bit 0 for the hard lockup detector and bit 1 for the soft lockup detector. | |
33 | * | |
34 | * 'watchdog_user_enabled', 'nmi_watchdog_enabled' and 'soft_watchdog_enabled' | |
35 | * are variables that are only used as an 'interface' between the parameters | |
36 | * in /proc/sys/kernel and the internal state bits in 'watchdog_enabled'. The | |
37 | * 'watchdog_thresh' variable is handled differently because its value is not | |
38 | * boolean, and the lockup detectors are 'suspended' while 'watchdog_thresh' | |
39 | * is equal zero. | |
40 | */ | |
41 | #define NMI_WATCHDOG_ENABLED_BIT 0 | |
42 | #define SOFT_WATCHDOG_ENABLED_BIT 1 | |
43 | #define NMI_WATCHDOG_ENABLED (1 << NMI_WATCHDOG_ENABLED_BIT) | |
44 | #define SOFT_WATCHDOG_ENABLED (1 << SOFT_WATCHDOG_ENABLED_BIT) | |
45 | ||
ab992dc3 PZ |
46 | static DEFINE_MUTEX(watchdog_proc_mutex); |
47 | ||
84d56e66 UO |
48 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
49 | static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED; | |
50 | #else | |
51 | static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED; | |
52 | #endif | |
53 | int __read_mostly nmi_watchdog_enabled; | |
54 | int __read_mostly soft_watchdog_enabled; | |
55 | int __read_mostly watchdog_user_enabled; | |
4eec42f3 | 56 | int __read_mostly watchdog_thresh = 10; |
84d56e66 | 57 | |
ed235875 AT |
58 | #ifdef CONFIG_SMP |
59 | int __read_mostly sysctl_softlockup_all_cpu_backtrace; | |
55537871 | 60 | int __read_mostly sysctl_hardlockup_all_cpu_backtrace; |
ed235875 AT |
61 | #else |
62 | #define sysctl_softlockup_all_cpu_backtrace 0 | |
55537871 | 63 | #define sysctl_hardlockup_all_cpu_backtrace 0 |
ed235875 | 64 | #endif |
fe4ba3c3 CM |
65 | static struct cpumask watchdog_cpumask __read_mostly; |
66 | unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask); | |
67 | ||
68 | /* Helper for online, unparked cpus. */ | |
69 | #define for_each_watchdog_cpu(cpu) \ | |
70 | for_each_cpu_and((cpu), cpu_online_mask, &watchdog_cpumask) | |
ed235875 | 71 | |
ec6a9066 UO |
72 | /* |
73 | * The 'watchdog_running' variable is set to 1 when the watchdog threads | |
74 | * are registered/started and is set to 0 when the watchdog threads are | |
75 | * unregistered/stopped, so it is an indicator whether the threads exist. | |
76 | */ | |
3c00ea82 | 77 | static int __read_mostly watchdog_running; |
ec6a9066 UO |
78 | /* |
79 | * If a subsystem has a need to deactivate the watchdog temporarily, it | |
80 | * can use the suspend/resume interface to achieve this. The content of | |
81 | * the 'watchdog_suspended' variable reflects this state. Existing threads | |
82 | * are parked/unparked by the lockup_detector_{suspend|resume} functions | |
83 | * (see comment blocks pertaining to those functions for further details). | |
84 | * | |
85 | * 'watchdog_suspended' also prevents threads from being registered/started | |
86 | * or unregistered/stopped via parameters in /proc/sys/kernel, so the state | |
87 | * of 'watchdog_running' cannot change while the watchdog is deactivated | |
88 | * temporarily (see related code in 'proc' handlers). | |
89 | */ | |
90 | static int __read_mostly watchdog_suspended; | |
91 | ||
0f34c400 | 92 | static u64 __read_mostly sample_period; |
58687acb DZ |
93 | |
94 | static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); | |
95 | static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog); | |
96 | static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer); | |
97 | static DEFINE_PER_CPU(bool, softlockup_touch_sync); | |
58687acb | 98 | static DEFINE_PER_CPU(bool, soft_watchdog_warn); |
bcd951cf TG |
99 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); |
100 | static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt); | |
b1a8de1f | 101 | static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved); |
23637d47 | 102 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
cafcd80d DZ |
103 | static DEFINE_PER_CPU(bool, hard_watchdog_warn); |
104 | static DEFINE_PER_CPU(bool, watchdog_nmi_touch); | |
58687acb DZ |
105 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); |
106 | static DEFINE_PER_CPU(struct perf_event *, watchdog_ev); | |
107 | #endif | |
ed235875 | 108 | static unsigned long soft_lockup_nmi_warn; |
58687acb | 109 | |
58687acb DZ |
110 | /* boot commands */ |
111 | /* | |
112 | * Should we panic when a soft-lockup or hard-lockup occurs: | |
113 | */ | |
23637d47 | 114 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
ac1f5912 | 115 | unsigned int __read_mostly hardlockup_panic = |
fef2c9bc | 116 | CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE; |
55537871 | 117 | static unsigned long hardlockup_allcpu_dumped; |
6e7458a6 UO |
118 | /* |
119 | * We may not want to enable hard lockup detection by default in all cases, | |
120 | * for example when running the kernel as a guest on a hypervisor. In these | |
121 | * cases this function can be called to disable hard lockup detection. This | |
122 | * function should only be executed once by the boot processor before the | |
123 | * kernel command line parameters are parsed, because otherwise it is not | |
124 | * possible to override this in hardlockup_panic_setup(). | |
125 | */ | |
692297d8 | 126 | void hardlockup_detector_disable(void) |
6e7458a6 | 127 | { |
692297d8 | 128 | watchdog_enabled &= ~NMI_WATCHDOG_ENABLED; |
6e7458a6 UO |
129 | } |
130 | ||
58687acb DZ |
131 | static int __init hardlockup_panic_setup(char *str) |
132 | { | |
133 | if (!strncmp(str, "panic", 5)) | |
134 | hardlockup_panic = 1; | |
fef2c9bc DZ |
135 | else if (!strncmp(str, "nopanic", 7)) |
136 | hardlockup_panic = 0; | |
5dc30558 | 137 | else if (!strncmp(str, "0", 1)) |
195daf66 UO |
138 | watchdog_enabled &= ~NMI_WATCHDOG_ENABLED; |
139 | else if (!strncmp(str, "1", 1)) | |
140 | watchdog_enabled |= NMI_WATCHDOG_ENABLED; | |
58687acb DZ |
141 | return 1; |
142 | } | |
143 | __setup("nmi_watchdog=", hardlockup_panic_setup); | |
144 | #endif | |
145 | ||
146 | unsigned int __read_mostly softlockup_panic = | |
147 | CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE; | |
148 | ||
149 | static int __init softlockup_panic_setup(char *str) | |
150 | { | |
151 | softlockup_panic = simple_strtoul(str, NULL, 0); | |
152 | ||
153 | return 1; | |
154 | } | |
155 | __setup("softlockup_panic=", softlockup_panic_setup); | |
156 | ||
157 | static int __init nowatchdog_setup(char *str) | |
158 | { | |
195daf66 | 159 | watchdog_enabled = 0; |
58687acb DZ |
160 | return 1; |
161 | } | |
162 | __setup("nowatchdog", nowatchdog_setup); | |
163 | ||
58687acb DZ |
164 | static int __init nosoftlockup_setup(char *str) |
165 | { | |
195daf66 | 166 | watchdog_enabled &= ~SOFT_WATCHDOG_ENABLED; |
58687acb DZ |
167 | return 1; |
168 | } | |
169 | __setup("nosoftlockup", nosoftlockup_setup); | |
195daf66 | 170 | |
ed235875 AT |
171 | #ifdef CONFIG_SMP |
172 | static int __init softlockup_all_cpu_backtrace_setup(char *str) | |
173 | { | |
174 | sysctl_softlockup_all_cpu_backtrace = | |
175 | !!simple_strtol(str, NULL, 0); | |
176 | return 1; | |
177 | } | |
178 | __setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup); | |
55537871 JK |
179 | static int __init hardlockup_all_cpu_backtrace_setup(char *str) |
180 | { | |
181 | sysctl_hardlockup_all_cpu_backtrace = | |
182 | !!simple_strtol(str, NULL, 0); | |
183 | return 1; | |
184 | } | |
185 | __setup("hardlockup_all_cpu_backtrace=", hardlockup_all_cpu_backtrace_setup); | |
ed235875 | 186 | #endif |
58687acb | 187 | |
4eec42f3 MSB |
188 | /* |
189 | * Hard-lockup warnings should be triggered after just a few seconds. Soft- | |
190 | * lockups can have false positives under extreme conditions. So we generally | |
191 | * want a higher threshold for soft lockups than for hard lockups. So we couple | |
192 | * the thresholds with a factor: we make the soft threshold twice the amount of | |
193 | * time the hard threshold is. | |
194 | */ | |
6e9101ae | 195 | static int get_softlockup_thresh(void) |
4eec42f3 MSB |
196 | { |
197 | return watchdog_thresh * 2; | |
198 | } | |
58687acb DZ |
199 | |
200 | /* | |
201 | * Returns seconds, approximately. We don't need nanosecond | |
202 | * resolution, and we don't need to waste time with a big divide when | |
203 | * 2^30ns == 1.074s. | |
204 | */ | |
c06b4f19 | 205 | static unsigned long get_timestamp(void) |
58687acb | 206 | { |
545a2bf7 | 207 | return running_clock() >> 30LL; /* 2^30 ~= 10^9 */ |
58687acb DZ |
208 | } |
209 | ||
0f34c400 | 210 | static void set_sample_period(void) |
58687acb DZ |
211 | { |
212 | /* | |
586692a5 | 213 | * convert watchdog_thresh from seconds to ns |
86f5e6a7 FLVC |
214 | * the divide by 5 is to give hrtimer several chances (two |
215 | * or three with the current relation between the soft | |
216 | * and hard thresholds) to increment before the | |
217 | * hardlockup detector generates a warning | |
58687acb | 218 | */ |
0f34c400 | 219 | sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); |
58687acb DZ |
220 | } |
221 | ||
222 | /* Commands for resetting the watchdog */ | |
223 | static void __touch_watchdog(void) | |
224 | { | |
c06b4f19 | 225 | __this_cpu_write(watchdog_touch_ts, get_timestamp()); |
58687acb DZ |
226 | } |
227 | ||
332fbdbc | 228 | void touch_softlockup_watchdog(void) |
58687acb | 229 | { |
7861144b AM |
230 | /* |
231 | * Preemption can be enabled. It doesn't matter which CPU's timestamp | |
232 | * gets zeroed here, so use the raw_ operation. | |
233 | */ | |
234 | raw_cpu_write(watchdog_touch_ts, 0); | |
58687acb | 235 | } |
0167c781 | 236 | EXPORT_SYMBOL(touch_softlockup_watchdog); |
58687acb | 237 | |
332fbdbc | 238 | void touch_all_softlockup_watchdogs(void) |
58687acb DZ |
239 | { |
240 | int cpu; | |
241 | ||
242 | /* | |
243 | * this is done lockless | |
244 | * do we care if a 0 races with a timestamp? | |
245 | * all it means is the softlock check starts one cycle later | |
246 | */ | |
fe4ba3c3 | 247 | for_each_watchdog_cpu(cpu) |
58687acb DZ |
248 | per_cpu(watchdog_touch_ts, cpu) = 0; |
249 | } | |
250 | ||
cafcd80d | 251 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb DZ |
252 | void touch_nmi_watchdog(void) |
253 | { | |
62572e29 BZ |
254 | /* |
255 | * Using __raw here because some code paths have | |
256 | * preemption enabled. If preemption is enabled | |
257 | * then interrupts should be enabled too, in which | |
258 | * case we shouldn't have to worry about the watchdog | |
259 | * going off. | |
260 | */ | |
f7f66b05 | 261 | raw_cpu_write(watchdog_nmi_touch, true); |
332fbdbc | 262 | touch_softlockup_watchdog(); |
58687acb DZ |
263 | } |
264 | EXPORT_SYMBOL(touch_nmi_watchdog); | |
265 | ||
cafcd80d DZ |
266 | #endif |
267 | ||
58687acb DZ |
268 | void touch_softlockup_watchdog_sync(void) |
269 | { | |
f7f66b05 CL |
270 | __this_cpu_write(softlockup_touch_sync, true); |
271 | __this_cpu_write(watchdog_touch_ts, 0); | |
58687acb DZ |
272 | } |
273 | ||
23637d47 | 274 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb | 275 | /* watchdog detector functions */ |
451637e4 | 276 | static bool is_hardlockup(void) |
58687acb | 277 | { |
909ea964 | 278 | unsigned long hrint = __this_cpu_read(hrtimer_interrupts); |
58687acb | 279 | |
909ea964 | 280 | if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) |
451637e4 | 281 | return true; |
58687acb | 282 | |
909ea964 | 283 | __this_cpu_write(hrtimer_interrupts_saved, hrint); |
451637e4 | 284 | return false; |
58687acb DZ |
285 | } |
286 | #endif | |
287 | ||
26e09c6e | 288 | static int is_softlockup(unsigned long touch_ts) |
58687acb | 289 | { |
c06b4f19 | 290 | unsigned long now = get_timestamp(); |
58687acb | 291 | |
39d2da21 | 292 | if ((watchdog_enabled & SOFT_WATCHDOG_ENABLED) && watchdog_thresh){ |
195daf66 UO |
293 | /* Warn about unreasonable delays. */ |
294 | if (time_after(now, touch_ts + get_softlockup_thresh())) | |
295 | return now - touch_ts; | |
296 | } | |
58687acb DZ |
297 | return 0; |
298 | } | |
299 | ||
23637d47 | 300 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
1880c4ae | 301 | |
58687acb DZ |
302 | static struct perf_event_attr wd_hw_attr = { |
303 | .type = PERF_TYPE_HARDWARE, | |
304 | .config = PERF_COUNT_HW_CPU_CYCLES, | |
305 | .size = sizeof(struct perf_event_attr), | |
306 | .pinned = 1, | |
307 | .disabled = 1, | |
308 | }; | |
309 | ||
310 | /* Callback function for perf event subsystem */ | |
a8b0ca17 | 311 | static void watchdog_overflow_callback(struct perf_event *event, |
58687acb DZ |
312 | struct perf_sample_data *data, |
313 | struct pt_regs *regs) | |
314 | { | |
c6db67cd PZ |
315 | /* Ensure the watchdog never gets throttled */ |
316 | event->hw.interrupts = 0; | |
317 | ||
909ea964 CL |
318 | if (__this_cpu_read(watchdog_nmi_touch) == true) { |
319 | __this_cpu_write(watchdog_nmi_touch, false); | |
58687acb DZ |
320 | return; |
321 | } | |
322 | ||
323 | /* check for a hardlockup | |
324 | * This is done by making sure our timer interrupt | |
325 | * is incrementing. The timer interrupt should have | |
326 | * fired multiple times before we overflow'd. If it hasn't | |
327 | * then this is a good indication the cpu is stuck | |
328 | */ | |
26e09c6e DZ |
329 | if (is_hardlockup()) { |
330 | int this_cpu = smp_processor_id(); | |
55537871 | 331 | struct pt_regs *regs = get_irq_regs(); |
26e09c6e | 332 | |
58687acb | 333 | /* only print hardlockups once */ |
909ea964 | 334 | if (__this_cpu_read(hard_watchdog_warn) == true) |
58687acb DZ |
335 | return; |
336 | ||
55537871 JK |
337 | pr_emerg("Watchdog detected hard LOCKUP on cpu %d", this_cpu); |
338 | print_modules(); | |
339 | print_irqtrace_events(current); | |
340 | if (regs) | |
341 | show_regs(regs); | |
58687acb | 342 | else |
55537871 JK |
343 | dump_stack(); |
344 | ||
345 | /* | |
346 | * Perform all-CPU dump only once to avoid multiple hardlockups | |
347 | * generating interleaving traces | |
348 | */ | |
349 | if (sysctl_hardlockup_all_cpu_backtrace && | |
350 | !test_and_set_bit(0, &hardlockup_allcpu_dumped)) | |
351 | trigger_allbutself_cpu_backtrace(); | |
352 | ||
353 | if (hardlockup_panic) | |
354 | panic("Hard LOCKUP"); | |
58687acb | 355 | |
909ea964 | 356 | __this_cpu_write(hard_watchdog_warn, true); |
58687acb DZ |
357 | return; |
358 | } | |
359 | ||
909ea964 | 360 | __this_cpu_write(hard_watchdog_warn, false); |
58687acb DZ |
361 | return; |
362 | } | |
bcd951cf TG |
363 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
364 | ||
58687acb DZ |
365 | static void watchdog_interrupt_count(void) |
366 | { | |
909ea964 | 367 | __this_cpu_inc(hrtimer_interrupts); |
58687acb | 368 | } |
bcd951cf TG |
369 | |
370 | static int watchdog_nmi_enable(unsigned int cpu); | |
371 | static void watchdog_nmi_disable(unsigned int cpu); | |
58687acb | 372 | |
58cf690a UO |
373 | static int watchdog_enable_all_cpus(void); |
374 | static void watchdog_disable_all_cpus(void); | |
375 | ||
58687acb DZ |
376 | /* watchdog kicker functions */ |
377 | static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) | |
378 | { | |
909ea964 | 379 | unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts); |
58687acb DZ |
380 | struct pt_regs *regs = get_irq_regs(); |
381 | int duration; | |
ed235875 | 382 | int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; |
58687acb DZ |
383 | |
384 | /* kick the hardlockup detector */ | |
385 | watchdog_interrupt_count(); | |
386 | ||
387 | /* kick the softlockup detector */ | |
909ea964 | 388 | wake_up_process(__this_cpu_read(softlockup_watchdog)); |
58687acb DZ |
389 | |
390 | /* .. and repeat */ | |
0f34c400 | 391 | hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period)); |
58687acb DZ |
392 | |
393 | if (touch_ts == 0) { | |
909ea964 | 394 | if (unlikely(__this_cpu_read(softlockup_touch_sync))) { |
58687acb DZ |
395 | /* |
396 | * If the time stamp was touched atomically | |
397 | * make sure the scheduler tick is up to date. | |
398 | */ | |
909ea964 | 399 | __this_cpu_write(softlockup_touch_sync, false); |
58687acb DZ |
400 | sched_clock_tick(); |
401 | } | |
5d1c0f4a EM |
402 | |
403 | /* Clear the guest paused flag on watchdog reset */ | |
404 | kvm_check_and_clear_guest_paused(); | |
58687acb DZ |
405 | __touch_watchdog(); |
406 | return HRTIMER_RESTART; | |
407 | } | |
408 | ||
409 | /* check for a softlockup | |
410 | * This is done by making sure a high priority task is | |
411 | * being scheduled. The task touches the watchdog to | |
412 | * indicate it is getting cpu time. If it hasn't then | |
413 | * this is a good indication some task is hogging the cpu | |
414 | */ | |
26e09c6e | 415 | duration = is_softlockup(touch_ts); |
58687acb | 416 | if (unlikely(duration)) { |
5d1c0f4a EM |
417 | /* |
418 | * If a virtual machine is stopped by the host it can look to | |
419 | * the watchdog like a soft lockup, check to see if the host | |
420 | * stopped the vm before we issue the warning | |
421 | */ | |
422 | if (kvm_check_and_clear_guest_paused()) | |
423 | return HRTIMER_RESTART; | |
424 | ||
58687acb | 425 | /* only warn once */ |
b1a8de1f | 426 | if (__this_cpu_read(soft_watchdog_warn) == true) { |
427 | /* | |
428 | * When multiple processes are causing softlockups the | |
429 | * softlockup detector only warns on the first one | |
430 | * because the code relies on a full quiet cycle to | |
431 | * re-arm. The second process prevents the quiet cycle | |
432 | * and never gets reported. Use task pointers to detect | |
433 | * this. | |
434 | */ | |
435 | if (__this_cpu_read(softlockup_task_ptr_saved) != | |
436 | current) { | |
437 | __this_cpu_write(soft_watchdog_warn, false); | |
438 | __touch_watchdog(); | |
439 | } | |
58687acb | 440 | return HRTIMER_RESTART; |
b1a8de1f | 441 | } |
58687acb | 442 | |
ed235875 AT |
443 | if (softlockup_all_cpu_backtrace) { |
444 | /* Prevent multiple soft-lockup reports if one cpu is already | |
445 | * engaged in dumping cpu back traces | |
446 | */ | |
447 | if (test_and_set_bit(0, &soft_lockup_nmi_warn)) { | |
448 | /* Someone else will report us. Let's give up */ | |
449 | __this_cpu_write(soft_watchdog_warn, true); | |
450 | return HRTIMER_RESTART; | |
451 | } | |
452 | } | |
453 | ||
656c3b79 | 454 | pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", |
26e09c6e | 455 | smp_processor_id(), duration, |
58687acb | 456 | current->comm, task_pid_nr(current)); |
b1a8de1f | 457 | __this_cpu_write(softlockup_task_ptr_saved, current); |
58687acb DZ |
458 | print_modules(); |
459 | print_irqtrace_events(current); | |
460 | if (regs) | |
461 | show_regs(regs); | |
462 | else | |
463 | dump_stack(); | |
464 | ||
ed235875 AT |
465 | if (softlockup_all_cpu_backtrace) { |
466 | /* Avoid generating two back traces for current | |
467 | * given that one is already made above | |
468 | */ | |
469 | trigger_allbutself_cpu_backtrace(); | |
470 | ||
471 | clear_bit(0, &soft_lockup_nmi_warn); | |
472 | /* Barrier to sync with other cpus */ | |
473 | smp_mb__after_atomic(); | |
474 | } | |
475 | ||
69361eef | 476 | add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK); |
58687acb DZ |
477 | if (softlockup_panic) |
478 | panic("softlockup: hung tasks"); | |
909ea964 | 479 | __this_cpu_write(soft_watchdog_warn, true); |
58687acb | 480 | } else |
909ea964 | 481 | __this_cpu_write(soft_watchdog_warn, false); |
58687acb DZ |
482 | |
483 | return HRTIMER_RESTART; | |
484 | } | |
485 | ||
bcd951cf TG |
486 | static void watchdog_set_prio(unsigned int policy, unsigned int prio) |
487 | { | |
488 | struct sched_param param = { .sched_priority = prio }; | |
58687acb | 489 | |
bcd951cf TG |
490 | sched_setscheduler(current, policy, ¶m); |
491 | } | |
492 | ||
493 | static void watchdog_enable(unsigned int cpu) | |
58687acb | 494 | { |
f7f66b05 | 495 | struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); |
58687acb | 496 | |
3935e895 BM |
497 | /* kick off the timer for the hardlockup detector */ |
498 | hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
499 | hrtimer->function = watchdog_timer_fn; | |
500 | ||
bcd951cf TG |
501 | /* Enable the perf event */ |
502 | watchdog_nmi_enable(cpu); | |
58687acb | 503 | |
58687acb | 504 | /* done here because hrtimer_start can only pin to smp_processor_id() */ |
0f34c400 | 505 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
58687acb DZ |
506 | HRTIMER_MODE_REL_PINNED); |
507 | ||
bcd951cf TG |
508 | /* initialize timestamp */ |
509 | watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1); | |
510 | __touch_watchdog(); | |
511 | } | |
58687acb | 512 | |
bcd951cf TG |
513 | static void watchdog_disable(unsigned int cpu) |
514 | { | |
f7f66b05 | 515 | struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); |
58687acb | 516 | |
bcd951cf TG |
517 | watchdog_set_prio(SCHED_NORMAL, 0); |
518 | hrtimer_cancel(hrtimer); | |
519 | /* disable the perf event */ | |
520 | watchdog_nmi_disable(cpu); | |
58687acb DZ |
521 | } |
522 | ||
b8900bc0 FW |
523 | static void watchdog_cleanup(unsigned int cpu, bool online) |
524 | { | |
525 | watchdog_disable(cpu); | |
526 | } | |
527 | ||
bcd951cf TG |
528 | static int watchdog_should_run(unsigned int cpu) |
529 | { | |
530 | return __this_cpu_read(hrtimer_interrupts) != | |
531 | __this_cpu_read(soft_lockup_hrtimer_cnt); | |
532 | } | |
533 | ||
534 | /* | |
535 | * The watchdog thread function - touches the timestamp. | |
536 | * | |
0f34c400 | 537 | * It only runs once every sample_period seconds (4 seconds by |
bcd951cf TG |
538 | * default) to reset the softlockup timestamp. If this gets delayed |
539 | * for more than 2*watchdog_thresh seconds then the debug-printout | |
540 | * triggers in watchdog_timer_fn(). | |
541 | */ | |
542 | static void watchdog(unsigned int cpu) | |
543 | { | |
544 | __this_cpu_write(soft_lockup_hrtimer_cnt, | |
545 | __this_cpu_read(hrtimer_interrupts)); | |
546 | __touch_watchdog(); | |
bcfba4f4 UO |
547 | |
548 | /* | |
549 | * watchdog_nmi_enable() clears the NMI_WATCHDOG_ENABLED bit in the | |
550 | * failure path. Check for failures that can occur asynchronously - | |
551 | * for example, when CPUs are on-lined - and shut down the hardware | |
552 | * perf event on each CPU accordingly. | |
553 | * | |
554 | * The only non-obvious place this bit can be cleared is through | |
555 | * watchdog_nmi_enable(), so a pr_info() is placed there. Placing a | |
556 | * pr_info here would be too noisy as it would result in a message | |
557 | * every few seconds if the hardlockup was disabled but the softlockup | |
558 | * enabled. | |
559 | */ | |
560 | if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED)) | |
561 | watchdog_nmi_disable(cpu); | |
bcd951cf | 562 | } |
58687acb | 563 | |
23637d47 | 564 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
a7027046 DZ |
565 | /* |
566 | * People like the simple clean cpu node info on boot. | |
567 | * Reduce the watchdog noise by only printing messages | |
568 | * that are different from what cpu0 displayed. | |
569 | */ | |
570 | static unsigned long cpu0_err; | |
571 | ||
bcd951cf | 572 | static int watchdog_nmi_enable(unsigned int cpu) |
58687acb DZ |
573 | { |
574 | struct perf_event_attr *wd_attr; | |
575 | struct perf_event *event = per_cpu(watchdog_ev, cpu); | |
576 | ||
195daf66 UO |
577 | /* nothing to do if the hard lockup detector is disabled */ |
578 | if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED)) | |
579 | goto out; | |
6e7458a6 | 580 | |
58687acb DZ |
581 | /* is it already setup and enabled? */ |
582 | if (event && event->state > PERF_EVENT_STATE_OFF) | |
583 | goto out; | |
584 | ||
585 | /* it is setup but not enabled */ | |
586 | if (event != NULL) | |
587 | goto out_enable; | |
588 | ||
58687acb | 589 | wd_attr = &wd_hw_attr; |
4eec42f3 | 590 | wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); |
1880c4ae CG |
591 | |
592 | /* Try to register using hardware perf events */ | |
4dc0da86 | 593 | event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL); |
a7027046 DZ |
594 | |
595 | /* save cpu0 error for future comparision */ | |
596 | if (cpu == 0 && IS_ERR(event)) | |
597 | cpu0_err = PTR_ERR(event); | |
598 | ||
58687acb | 599 | if (!IS_ERR(event)) { |
a7027046 DZ |
600 | /* only print for cpu0 or different than cpu0 */ |
601 | if (cpu == 0 || cpu0_err) | |
602 | pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n"); | |
58687acb DZ |
603 | goto out_save; |
604 | } | |
605 | ||
bcfba4f4 UO |
606 | /* |
607 | * Disable the hard lockup detector if _any_ CPU fails to set up | |
608 | * set up the hardware perf event. The watchdog() function checks | |
609 | * the NMI_WATCHDOG_ENABLED bit periodically. | |
610 | * | |
611 | * The barriers are for syncing up watchdog_enabled across all the | |
612 | * cpus, as clear_bit() does not use barriers. | |
613 | */ | |
614 | smp_mb__before_atomic(); | |
615 | clear_bit(NMI_WATCHDOG_ENABLED_BIT, &watchdog_enabled); | |
616 | smp_mb__after_atomic(); | |
617 | ||
a7027046 DZ |
618 | /* skip displaying the same error again */ |
619 | if (cpu > 0 && (PTR_ERR(event) == cpu0_err)) | |
620 | return PTR_ERR(event); | |
5651f7f4 DZ |
621 | |
622 | /* vary the KERN level based on the returned errno */ | |
623 | if (PTR_ERR(event) == -EOPNOTSUPP) | |
4501980a | 624 | pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu); |
5651f7f4 | 625 | else if (PTR_ERR(event) == -ENOENT) |
656c3b79 | 626 | pr_warn("disabled (cpu%i): hardware events not enabled\n", |
4501980a | 627 | cpu); |
5651f7f4 | 628 | else |
4501980a AM |
629 | pr_err("disabled (cpu%i): unable to create perf event: %ld\n", |
630 | cpu, PTR_ERR(event)); | |
bcfba4f4 UO |
631 | |
632 | pr_info("Shutting down hard lockup detector on all cpus\n"); | |
633 | ||
eac24335 | 634 | return PTR_ERR(event); |
58687acb DZ |
635 | |
636 | /* success path */ | |
637 | out_save: | |
638 | per_cpu(watchdog_ev, cpu) = event; | |
639 | out_enable: | |
640 | perf_event_enable(per_cpu(watchdog_ev, cpu)); | |
641 | out: | |
642 | return 0; | |
643 | } | |
644 | ||
bcd951cf | 645 | static void watchdog_nmi_disable(unsigned int cpu) |
58687acb DZ |
646 | { |
647 | struct perf_event *event = per_cpu(watchdog_ev, cpu); | |
648 | ||
649 | if (event) { | |
650 | perf_event_disable(event); | |
651 | per_cpu(watchdog_ev, cpu) = NULL; | |
652 | ||
653 | /* should be in cleanup, but blocks oprofile */ | |
654 | perf_event_release_kernel(event); | |
655 | } | |
df577149 UO |
656 | if (cpu == 0) { |
657 | /* watchdog_nmi_enable() expects this to be zero initially. */ | |
658 | cpu0_err = 0; | |
659 | } | |
58687acb | 660 | } |
b3738d29 | 661 | |
58687acb | 662 | #else |
bcd951cf TG |
663 | static int watchdog_nmi_enable(unsigned int cpu) { return 0; } |
664 | static void watchdog_nmi_disable(unsigned int cpu) { return; } | |
23637d47 | 665 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
58687acb | 666 | |
b8900bc0 FW |
667 | static struct smp_hotplug_thread watchdog_threads = { |
668 | .store = &softlockup_watchdog, | |
669 | .thread_should_run = watchdog_should_run, | |
670 | .thread_fn = watchdog, | |
671 | .thread_comm = "watchdog/%u", | |
672 | .setup = watchdog_enable, | |
673 | .cleanup = watchdog_cleanup, | |
674 | .park = watchdog_disable, | |
675 | .unpark = watchdog_enable, | |
676 | }; | |
677 | ||
81a4beef UO |
678 | /* |
679 | * park all watchdog threads that are specified in 'watchdog_cpumask' | |
ee7fed54 UO |
680 | * |
681 | * This function returns an error if kthread_park() of a watchdog thread | |
682 | * fails. In this situation, the watchdog threads of some CPUs can already | |
683 | * be parked and the watchdog threads of other CPUs can still be runnable. | |
684 | * Callers are expected to handle this special condition as appropriate in | |
685 | * their context. | |
a2a45b85 UO |
686 | * |
687 | * This function may only be called in a context that is protected against | |
688 | * races with CPU hotplug - for example, via get_online_cpus(). | |
81a4beef UO |
689 | */ |
690 | static int watchdog_park_threads(void) | |
691 | { | |
692 | int cpu, ret = 0; | |
693 | ||
81a4beef UO |
694 | for_each_watchdog_cpu(cpu) { |
695 | ret = kthread_park(per_cpu(softlockup_watchdog, cpu)); | |
696 | if (ret) | |
697 | break; | |
698 | } | |
81a4beef UO |
699 | |
700 | return ret; | |
701 | } | |
702 | ||
703 | /* | |
704 | * unpark all watchdog threads that are specified in 'watchdog_cpumask' | |
a2a45b85 UO |
705 | * |
706 | * This function may only be called in a context that is protected against | |
707 | * races with CPU hotplug - for example, via get_online_cpus(). | |
81a4beef UO |
708 | */ |
709 | static void watchdog_unpark_threads(void) | |
710 | { | |
711 | int cpu; | |
712 | ||
81a4beef UO |
713 | for_each_watchdog_cpu(cpu) |
714 | kthread_unpark(per_cpu(softlockup_watchdog, cpu)); | |
81a4beef UO |
715 | } |
716 | ||
8c073d27 UO |
717 | /* |
718 | * Suspend the hard and soft lockup detector by parking the watchdog threads. | |
719 | */ | |
ec6a9066 | 720 | int lockup_detector_suspend(void) |
8c073d27 UO |
721 | { |
722 | int ret = 0; | |
723 | ||
ee89e71e | 724 | get_online_cpus(); |
8c073d27 UO |
725 | mutex_lock(&watchdog_proc_mutex); |
726 | /* | |
727 | * Multiple suspend requests can be active in parallel (counted by | |
728 | * the 'watchdog_suspended' variable). If the watchdog threads are | |
729 | * running, the first caller takes care that they will be parked. | |
730 | * The state of 'watchdog_running' cannot change while a suspend | |
ec6a9066 | 731 | * request is active (see related code in 'proc' handlers). |
8c073d27 UO |
732 | */ |
733 | if (watchdog_running && !watchdog_suspended) | |
734 | ret = watchdog_park_threads(); | |
735 | ||
736 | if (ret == 0) | |
737 | watchdog_suspended++; | |
c993590c UO |
738 | else { |
739 | watchdog_disable_all_cpus(); | |
740 | pr_err("Failed to suspend lockup detectors, disabled\n"); | |
741 | watchdog_enabled = 0; | |
742 | } | |
8c073d27 UO |
743 | |
744 | mutex_unlock(&watchdog_proc_mutex); | |
745 | ||
746 | return ret; | |
747 | } | |
748 | ||
749 | /* | |
750 | * Resume the hard and soft lockup detector by unparking the watchdog threads. | |
751 | */ | |
ec6a9066 | 752 | void lockup_detector_resume(void) |
8c073d27 UO |
753 | { |
754 | mutex_lock(&watchdog_proc_mutex); | |
755 | ||
756 | watchdog_suspended--; | |
757 | /* | |
758 | * The watchdog threads are unparked if they were previously running | |
759 | * and if there is no more active suspend request. | |
760 | */ | |
761 | if (watchdog_running && !watchdog_suspended) | |
762 | watchdog_unpark_threads(); | |
763 | ||
764 | mutex_unlock(&watchdog_proc_mutex); | |
ee89e71e | 765 | put_online_cpus(); |
8c073d27 UO |
766 | } |
767 | ||
b43cb43c | 768 | static int update_watchdog_all_cpus(void) |
9809b18f | 769 | { |
b43cb43c UO |
770 | int ret; |
771 | ||
772 | ret = watchdog_park_threads(); | |
773 | if (ret) | |
774 | return ret; | |
775 | ||
d4bdd0b2 | 776 | watchdog_unpark_threads(); |
b43cb43c UO |
777 | |
778 | return 0; | |
9809b18f MH |
779 | } |
780 | ||
b2f57c3a | 781 | static int watchdog_enable_all_cpus(void) |
58687acb | 782 | { |
b8900bc0 | 783 | int err = 0; |
58687acb | 784 | |
3c00ea82 | 785 | if (!watchdog_running) { |
230ec939 FW |
786 | err = smpboot_register_percpu_thread_cpumask(&watchdog_threads, |
787 | &watchdog_cpumask); | |
b8900bc0 FW |
788 | if (err) |
789 | pr_err("Failed to create watchdog threads, disabled\n"); | |
230ec939 | 790 | else |
3c00ea82 | 791 | watchdog_running = 1; |
b2f57c3a UO |
792 | } else { |
793 | /* | |
794 | * Enable/disable the lockup detectors or | |
795 | * change the sample period 'on the fly'. | |
796 | */ | |
b43cb43c UO |
797 | err = update_watchdog_all_cpus(); |
798 | ||
799 | if (err) { | |
800 | watchdog_disable_all_cpus(); | |
801 | pr_err("Failed to update lockup detectors, disabled\n"); | |
802 | } | |
bcd951cf | 803 | } |
b8900bc0 | 804 | |
b43cb43c UO |
805 | if (err) |
806 | watchdog_enabled = 0; | |
807 | ||
b8900bc0 | 808 | return err; |
58687acb DZ |
809 | } |
810 | ||
811 | static void watchdog_disable_all_cpus(void) | |
812 | { | |
3c00ea82 FW |
813 | if (watchdog_running) { |
814 | watchdog_running = 0; | |
b8900bc0 | 815 | smpboot_unregister_percpu_thread(&watchdog_threads); |
bcd951cf | 816 | } |
58687acb DZ |
817 | } |
818 | ||
58cf690a UO |
819 | #ifdef CONFIG_SYSCTL |
820 | ||
58687acb | 821 | /* |
a0c9cbb9 UO |
822 | * Update the run state of the lockup detectors. |
823 | */ | |
824 | static int proc_watchdog_update(void) | |
825 | { | |
826 | int err = 0; | |
827 | ||
828 | /* | |
829 | * Watchdog threads won't be started if they are already active. | |
830 | * The 'watchdog_running' variable in watchdog_*_all_cpus() takes | |
831 | * care of this. If those threads are already active, the sample | |
832 | * period will be updated and the lockup detectors will be enabled | |
833 | * or disabled 'on the fly'. | |
834 | */ | |
835 | if (watchdog_enabled && watchdog_thresh) | |
b2f57c3a | 836 | err = watchdog_enable_all_cpus(); |
a0c9cbb9 UO |
837 | else |
838 | watchdog_disable_all_cpus(); | |
839 | ||
840 | return err; | |
841 | ||
842 | } | |
843 | ||
ef246a21 UO |
844 | /* |
845 | * common function for watchdog, nmi_watchdog and soft_watchdog parameter | |
846 | * | |
847 | * caller | table->data points to | 'which' contains the flag(s) | |
848 | * -------------------|-----------------------|----------------------------- | |
849 | * proc_watchdog | watchdog_user_enabled | NMI_WATCHDOG_ENABLED or'ed | |
850 | * | | with SOFT_WATCHDOG_ENABLED | |
851 | * -------------------|-----------------------|----------------------------- | |
852 | * proc_nmi_watchdog | nmi_watchdog_enabled | NMI_WATCHDOG_ENABLED | |
853 | * -------------------|-----------------------|----------------------------- | |
854 | * proc_soft_watchdog | soft_watchdog_enabled | SOFT_WATCHDOG_ENABLED | |
855 | */ | |
856 | static int proc_watchdog_common(int which, struct ctl_table *table, int write, | |
857 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
858 | { | |
859 | int err, old, new; | |
860 | int *watchdog_param = (int *)table->data; | |
861 | ||
8614ddef | 862 | get_online_cpus(); |
ef246a21 UO |
863 | mutex_lock(&watchdog_proc_mutex); |
864 | ||
8c073d27 UO |
865 | if (watchdog_suspended) { |
866 | /* no parameter changes allowed while watchdog is suspended */ | |
867 | err = -EAGAIN; | |
868 | goto out; | |
869 | } | |
870 | ||
ef246a21 UO |
871 | /* |
872 | * If the parameter is being read return the state of the corresponding | |
873 | * bit(s) in 'watchdog_enabled', else update 'watchdog_enabled' and the | |
874 | * run state of the lockup detectors. | |
875 | */ | |
876 | if (!write) { | |
877 | *watchdog_param = (watchdog_enabled & which) != 0; | |
878 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); | |
879 | } else { | |
880 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); | |
881 | if (err) | |
882 | goto out; | |
883 | ||
884 | /* | |
885 | * There is a race window between fetching the current value | |
886 | * from 'watchdog_enabled' and storing the new value. During | |
887 | * this race window, watchdog_nmi_enable() can sneak in and | |
888 | * clear the NMI_WATCHDOG_ENABLED bit in 'watchdog_enabled'. | |
889 | * The 'cmpxchg' detects this race and the loop retries. | |
890 | */ | |
891 | do { | |
892 | old = watchdog_enabled; | |
893 | /* | |
894 | * If the parameter value is not zero set the | |
895 | * corresponding bit(s), else clear it(them). | |
896 | */ | |
897 | if (*watchdog_param) | |
898 | new = old | which; | |
899 | else | |
900 | new = old & ~which; | |
901 | } while (cmpxchg(&watchdog_enabled, old, new) != old); | |
902 | ||
903 | /* | |
b43cb43c UO |
904 | * Update the run state of the lockup detectors. There is _no_ |
905 | * need to check the value returned by proc_watchdog_update() | |
906 | * and to restore the previous value of 'watchdog_enabled' as | |
907 | * both lockup detectors are disabled if proc_watchdog_update() | |
908 | * returns an error. | |
ef246a21 UO |
909 | */ |
910 | err = proc_watchdog_update(); | |
ef246a21 UO |
911 | } |
912 | out: | |
913 | mutex_unlock(&watchdog_proc_mutex); | |
8614ddef | 914 | put_online_cpus(); |
ef246a21 UO |
915 | return err; |
916 | } | |
917 | ||
83a80a39 UO |
918 | /* |
919 | * /proc/sys/kernel/watchdog | |
920 | */ | |
921 | int proc_watchdog(struct ctl_table *table, int write, | |
922 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
923 | { | |
924 | return proc_watchdog_common(NMI_WATCHDOG_ENABLED|SOFT_WATCHDOG_ENABLED, | |
925 | table, write, buffer, lenp, ppos); | |
926 | } | |
927 | ||
928 | /* | |
929 | * /proc/sys/kernel/nmi_watchdog | |
58687acb | 930 | */ |
83a80a39 UO |
931 | int proc_nmi_watchdog(struct ctl_table *table, int write, |
932 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
933 | { | |
934 | return proc_watchdog_common(NMI_WATCHDOG_ENABLED, | |
935 | table, write, buffer, lenp, ppos); | |
936 | } | |
937 | ||
938 | /* | |
939 | * /proc/sys/kernel/soft_watchdog | |
940 | */ | |
941 | int proc_soft_watchdog(struct ctl_table *table, int write, | |
942 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
943 | { | |
944 | return proc_watchdog_common(SOFT_WATCHDOG_ENABLED, | |
945 | table, write, buffer, lenp, ppos); | |
946 | } | |
58687acb | 947 | |
83a80a39 UO |
948 | /* |
949 | * /proc/sys/kernel/watchdog_thresh | |
950 | */ | |
951 | int proc_watchdog_thresh(struct ctl_table *table, int write, | |
952 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
58687acb | 953 | { |
83a80a39 | 954 | int err, old; |
58687acb | 955 | |
8614ddef | 956 | get_online_cpus(); |
359e6fab | 957 | mutex_lock(&watchdog_proc_mutex); |
bcd951cf | 958 | |
8c073d27 UO |
959 | if (watchdog_suspended) { |
960 | /* no parameter changes allowed while watchdog is suspended */ | |
961 | err = -EAGAIN; | |
962 | goto out; | |
963 | } | |
964 | ||
83a80a39 | 965 | old = ACCESS_ONCE(watchdog_thresh); |
b8900bc0 | 966 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
83a80a39 | 967 | |
b8900bc0 | 968 | if (err || !write) |
359e6fab | 969 | goto out; |
e04ab2bc | 970 | |
b66a2356 | 971 | /* |
d283c640 | 972 | * Update the sample period. Restore on failure. |
b66a2356 | 973 | */ |
83a80a39 UO |
974 | set_sample_period(); |
975 | err = proc_watchdog_update(); | |
d283c640 | 976 | if (err) { |
83a80a39 | 977 | watchdog_thresh = old; |
d283c640 UO |
978 | set_sample_period(); |
979 | } | |
359e6fab MH |
980 | out: |
981 | mutex_unlock(&watchdog_proc_mutex); | |
8614ddef | 982 | put_online_cpus(); |
b8900bc0 | 983 | return err; |
58687acb | 984 | } |
fe4ba3c3 CM |
985 | |
986 | /* | |
987 | * The cpumask is the mask of possible cpus that the watchdog can run | |
988 | * on, not the mask of cpus it is actually running on. This allows the | |
989 | * user to specify a mask that will include cpus that have not yet | |
990 | * been brought online, if desired. | |
991 | */ | |
992 | int proc_watchdog_cpumask(struct ctl_table *table, int write, | |
993 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
994 | { | |
995 | int err; | |
996 | ||
8614ddef | 997 | get_online_cpus(); |
fe4ba3c3 | 998 | mutex_lock(&watchdog_proc_mutex); |
8c073d27 UO |
999 | |
1000 | if (watchdog_suspended) { | |
1001 | /* no parameter changes allowed while watchdog is suspended */ | |
1002 | err = -EAGAIN; | |
1003 | goto out; | |
1004 | } | |
1005 | ||
fe4ba3c3 CM |
1006 | err = proc_do_large_bitmap(table, write, buffer, lenp, ppos); |
1007 | if (!err && write) { | |
1008 | /* Remove impossible cpus to keep sysctl output cleaner. */ | |
1009 | cpumask_and(&watchdog_cpumask, &watchdog_cpumask, | |
1010 | cpu_possible_mask); | |
1011 | ||
1012 | if (watchdog_running) { | |
1013 | /* | |
1014 | * Failure would be due to being unable to allocate | |
1015 | * a temporary cpumask, so we are likely not in a | |
1016 | * position to do much else to make things better. | |
1017 | */ | |
1018 | if (smpboot_update_cpumask_percpu_thread( | |
1019 | &watchdog_threads, &watchdog_cpumask) != 0) | |
1020 | pr_err("cpumask update failed\n"); | |
1021 | } | |
1022 | } | |
8c073d27 | 1023 | out: |
fe4ba3c3 | 1024 | mutex_unlock(&watchdog_proc_mutex); |
8614ddef | 1025 | put_online_cpus(); |
fe4ba3c3 CM |
1026 | return err; |
1027 | } | |
1028 | ||
58687acb DZ |
1029 | #endif /* CONFIG_SYSCTL */ |
1030 | ||
004417a6 | 1031 | void __init lockup_detector_init(void) |
58687acb | 1032 | { |
0f34c400 | 1033 | set_sample_period(); |
b8900bc0 | 1034 | |
fe4ba3c3 CM |
1035 | #ifdef CONFIG_NO_HZ_FULL |
1036 | if (tick_nohz_full_enabled()) { | |
314b08ff FW |
1037 | pr_info("Disabling watchdog on nohz_full cores by default\n"); |
1038 | cpumask_copy(&watchdog_cpumask, housekeeping_mask); | |
fe4ba3c3 CM |
1039 | } else |
1040 | cpumask_copy(&watchdog_cpumask, cpu_possible_mask); | |
1041 | #else | |
1042 | cpumask_copy(&watchdog_cpumask, cpu_possible_mask); | |
1043 | #endif | |
1044 | ||
195daf66 | 1045 | if (watchdog_enabled) |
b2f57c3a | 1046 | watchdog_enable_all_cpus(); |
58687acb | 1047 | } |