kernel/watchdog.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Detect hard and soft lockups on a system
   4  *
   5  * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
   6  *
   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
  10  * to those contributors as well.
  11  */
  12
  13 #define pr_fmt(fmt) "watchdog: " fmt
  14
  15 #include <linux/cpu.h>
  16 #include <linux/init.h>
  17 #include <linux/irq.h>
  18 #include <linux/irqdesc.h>
  19 #include <linux/kernel_stat.h>
  20 #include <linux/kvm_para.h>
  21 #include <linux/math64.h>
  22 #include <linux/mm.h>
  23 #include <linux/module.h>
  24 #include <linux/nmi.h>
  25 #include <linux/stop_machine.h>
  26 #include <linux/sysctl.h>
  27 #include <linux/tick.h>
  28
  29 #include <linux/sched/clock.h>
  30 #include <linux/sched/debug.h>
  31 #include <linux/sched/isolation.h>
  32
  33 #include <asm/irq_regs.h>
  34
  35 static DEFINE_MUTEX(watchdog_mutex);
  36
  37 #if defined(CONFIG_HARDLOCKUP_DETECTOR) || defined(CONFIG_HARDLOCKUP_DETECTOR_SPARC64)
  38 # define WATCHDOG_HARDLOCKUP_DEFAULT    1
  39 #else
  40 # define WATCHDOG_HARDLOCKUP_DEFAULT    0
  41 #endif
  42
  43 #define NUM_SAMPLE_PERIODS      5
  44
  45 unsigned long __read_mostly watchdog_enabled;
  46 int __read_mostly watchdog_user_enabled = 1;
  47 static int __read_mostly watchdog_hardlockup_user_enabled = WATCHDOG_HARDLOCKUP_DEFAULT;
  48 static int __read_mostly watchdog_softlockup_user_enabled = 1;
  49 int __read_mostly watchdog_thresh = 10;
  50 static int __read_mostly watchdog_hardlockup_available;
  51
  52 struct cpumask watchdog_cpumask __read_mostly;
  53 unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask);
  54
  55 #ifdef CONFIG_HARDLOCKUP_DETECTOR
  56
  57 # ifdef CONFIG_SMP
  58 int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
  59 # endif /* CONFIG_SMP */
  60
  61 /*
  62  * Should we panic when a soft-lockup or hard-lockup occurs:
  63  */
  64 unsigned int __read_mostly hardlockup_panic =
  65                         IS_ENABLED(CONFIG_BOOTPARAM_HARDLOCKUP_PANIC);
  66 /*
  67  * We may not want to enable hard lockup detection by default in all cases,
  68  * for example when running the kernel as a guest on a hypervisor. In these
  69  * cases this function can be called to disable hard lockup detection. This
  70  * function should only be executed once by the boot processor before the
  71  * kernel command line parameters are parsed, because otherwise it is not
  72  * possible to override this in hardlockup_panic_setup().
  73  */
  74 void __init hardlockup_detector_disable(void)
  75 {
  76         watchdog_hardlockup_user_enabled = 0;
  77 }
  78
  79 static int __init hardlockup_panic_setup(char *str)
  80 {
  81 next:
  82         if (!strncmp(str, "panic", 5))
  83                 hardlockup_panic = 1;
  84         else if (!strncmp(str, "nopanic", 7))
  85                 hardlockup_panic = 0;
  86         else if (!strncmp(str, "0", 1))
  87                 watchdog_hardlockup_user_enabled = 0;
  88         else if (!strncmp(str, "1", 1))
  89                 watchdog_hardlockup_user_enabled = 1;
  90         else if (!strncmp(str, "r", 1))
  91                 hardlockup_config_perf_event(str + 1);
  92         while (*(str++)) {
  93                 if (*str == ',') {
  94                         str++;
  95                         goto next;
  96                 }
  97         }
  98         return 1;
  99 }
 100 __setup("nmi_watchdog=", hardlockup_panic_setup);
 101
 102 #endif /* CONFIG_HARDLOCKUP_DETECTOR */
 103
 104 #if defined(CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER)
 105
 106 static DEFINE_PER_CPU(atomic_t, hrtimer_interrupts);
 107 static DEFINE_PER_CPU(int, hrtimer_interrupts_saved);
 108 static DEFINE_PER_CPU(bool, watchdog_hardlockup_warned);
 109 static DEFINE_PER_CPU(bool, watchdog_hardlockup_touched);
 110 static unsigned long hard_lockup_nmi_warn;
 111
 112 notrace void arch_touch_nmi_watchdog(void)
 113 {
 114         /*
 115          * Using __raw here because some code paths have
 116          * preemption enabled.  If preemption is enabled
 117          * then interrupts should be enabled too, in which
 118          * case we shouldn't have to worry about the watchdog
 119          * going off.
 120          */
 121         raw_cpu_write(watchdog_hardlockup_touched, true);
 122 }
 123 EXPORT_SYMBOL(arch_touch_nmi_watchdog);
 124
 125 void watchdog_hardlockup_touch_cpu(unsigned int cpu)
 126 {
 127         per_cpu(watchdog_hardlockup_touched, cpu) = true;
 128 }
 129
 130 static bool is_hardlockup(unsigned int cpu)
 131 {
 132         int hrint = atomic_read(&per_cpu(hrtimer_interrupts, cpu));
 133
 134         if (per_cpu(hrtimer_interrupts_saved, cpu) == hrint)
 135                 return true;
 136
 137         /*
 138          * NOTE: we don't need any fancy atomic_t or READ_ONCE/WRITE_ONCE
 139          * for hrtimer_interrupts_saved. hrtimer_interrupts_saved is
 140          * written/read by a single CPU.
 141          */
 142         per_cpu(hrtimer_interrupts_saved, cpu) = hrint;
 143
 144         return false;
 145 }
 146
 147 static void watchdog_hardlockup_kick(void)
 148 {
 149         int new_interrupts;
 150
 151         new_interrupts = atomic_inc_return(this_cpu_ptr(&hrtimer_interrupts));
 152         watchdog_buddy_check_hardlockup(new_interrupts);
 153 }
 154
 155 void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs)
 156 {
 157         if (per_cpu(watchdog_hardlockup_touched, cpu)) {
 158                 per_cpu(watchdog_hardlockup_touched, cpu) = false;
 159                 return;
 160         }
 161
 162         /*
 163          * Check for a hardlockup by making sure the CPU's timer
 164          * interrupt is incrementing. The timer interrupt should have
 165          * fired multiple times before we overflow'd. If it hasn't
 166          * then this is a good indication the cpu is stuck
 167          */
 168         if (is_hardlockup(cpu)) {
 169                 unsigned int this_cpu = smp_processor_id();
 170                 unsigned long flags;
 171
 172                 /* Only print hardlockups once. */
 173                 if (per_cpu(watchdog_hardlockup_warned, cpu))
 174                         return;
 175
 176                 /*
 177                  * Prevent multiple hard-lockup reports if one cpu is already
 178                  * engaged in dumping all cpu back traces.
 179                  */
 180                 if (sysctl_hardlockup_all_cpu_backtrace) {
 181                         if (test_and_set_bit_lock(0, &hard_lockup_nmi_warn))
 182                                 return;
 183                 }
 184
 185                 /*
 186                  * NOTE: we call printk_cpu_sync_get_irqsave() after printing
 187                  * the lockup message. While it would be nice to serialize
 188                  * that printout, we really want to make sure that if some
 189                  * other CPU somehow locked up while holding the lock associated
 190                  * with printk_cpu_sync_get_irqsave() that we can still at least
 191                  * get the message about the lockup out.
 192                  */
 193                 pr_emerg("Watchdog detected hard LOCKUP on cpu %d\n", cpu);
 194                 printk_cpu_sync_get_irqsave(flags);
 195
 196                 print_modules();
 197                 print_irqtrace_events(current);
 198                 if (cpu == this_cpu) {
 199                         if (regs)
 200                                 show_regs(regs);
 201                         else
 202                                 dump_stack();
 203                         printk_cpu_sync_put_irqrestore(flags);
 204                 } else {
 205                         printk_cpu_sync_put_irqrestore(flags);
 206                         trigger_single_cpu_backtrace(cpu);
 207                 }
 208
 209                 if (sysctl_hardlockup_all_cpu_backtrace) {
 210                         trigger_allbutcpu_cpu_backtrace(cpu);
 211                         if (!hardlockup_panic)
 212                                 clear_bit_unlock(0, &hard_lockup_nmi_warn);
 213                 }
 214
 215                 if (hardlockup_panic)
 216                         nmi_panic(regs, "Hard LOCKUP");
 217
 218                 per_cpu(watchdog_hardlockup_warned, cpu) = true;
 219         } else {
 220                 per_cpu(watchdog_hardlockup_warned, cpu) = false;
 221         }
 222 }
 223
 224 #else /* CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER */
 225
 226 static inline void watchdog_hardlockup_kick(void) { }
 227
 228 #endif /* !CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER */
 229
 230 /*
 231  * These functions can be overridden based on the configured hardlockdup detector.
 232  *
 233  * watchdog_hardlockup_enable/disable can be implemented to start and stop when
 234  * softlockup watchdog start and stop. The detector must select the
 235  * SOFTLOCKUP_DETECTOR Kconfig.
 236  */
 237 void __weak watchdog_hardlockup_enable(unsigned int cpu) { }
 238
 239 void __weak watchdog_hardlockup_disable(unsigned int cpu) { }
 240
 241 /*
 242  * Watchdog-detector specific API.
 243  *
 244  * Return 0 when hardlockup watchdog is available, negative value otherwise.
 245  * Note that the negative value means that a delayed probe might
 246  * succeed later.
 247  */
 248 int __weak __init watchdog_hardlockup_probe(void)
 249 {
 250         return -ENODEV;
 251 }
 252
 253 /**
 254  * watchdog_hardlockup_stop - Stop the watchdog for reconfiguration
 255  *
 256  * The reconfiguration steps are:
 257  * watchdog_hardlockup_stop();
 258  * update_variables();
 259  * watchdog_hardlockup_start();
 260  */
 261 void __weak watchdog_hardlockup_stop(void) { }
 262
 263 /**
 264  * watchdog_hardlockup_start - Start the watchdog after reconfiguration
 265  *
 266  * Counterpart to watchdog_hardlockup_stop().
 267  *
 268  * The following variables have been updated in update_variables() and
 269  * contain the currently valid configuration:
 270  * - watchdog_enabled
 271  * - watchdog_thresh
 272  * - watchdog_cpumask
 273  */
 274 void __weak watchdog_hardlockup_start(void) { }
 275
 276 /**
 277  * lockup_detector_update_enable - Update the sysctl enable bit
 278  *
 279  * Caller needs to make sure that the hard watchdogs are off, so this
 280  * can't race with watchdog_hardlockup_disable().
 281  */
 282 static void lockup_detector_update_enable(void)
 283 {
 284         watchdog_enabled = 0;
 285         if (!watchdog_user_enabled)
 286                 return;
 287         if (watchdog_hardlockup_available && watchdog_hardlockup_user_enabled)
 288                 watchdog_enabled |= WATCHDOG_HARDLOCKUP_ENABLED;
 289         if (watchdog_softlockup_user_enabled)
 290                 watchdog_enabled |= WATCHDOG_SOFTOCKUP_ENABLED;
 291 }
 292
 293 #ifdef CONFIG_SOFTLOCKUP_DETECTOR
 294
 295 /*
 296  * Delay the soflockup report when running a known slow code.
 297  * It does _not_ affect the timestamp of the last successdul reschedule.
 298  */
 299 #define SOFTLOCKUP_DELAY_REPORT ULONG_MAX
 300
 301 #ifdef CONFIG_SMP
 302 int __read_mostly sysctl_softlockup_all_cpu_backtrace;
 303 #endif
 304
 305 static struct cpumask watchdog_allowed_mask __read_mostly;
 306
 307 /* Global variables, exported for sysctl */
 308 unsigned int __read_mostly softlockup_panic =
 309                         IS_ENABLED(CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC);
 310
 311 static bool softlockup_initialized __read_mostly;
 312 static u64 __read_mostly sample_period;
 313
 314 /* Timestamp taken after the last successful reschedule. */
 315 static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
 316 /* Timestamp of the last softlockup report. */
 317 static DEFINE_PER_CPU(unsigned long, watchdog_report_ts);
 318 static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer);
 319 static DEFINE_PER_CPU(bool, softlockup_touch_sync);
 320 static unsigned long soft_lockup_nmi_warn;
 321
 322 static int __init softlockup_panic_setup(char *str)
 323 {
 324         softlockup_panic = simple_strtoul(str, NULL, 0);
 325         return 1;
 326 }
 327 __setup("softlockup_panic=", softlockup_panic_setup);
 328
 329 static int __init nowatchdog_setup(char *str)
 330 {
 331         watchdog_user_enabled = 0;
 332         return 1;
 333 }
 334 __setup("nowatchdog", nowatchdog_setup);
 335
 336 static int __init nosoftlockup_setup(char *str)
 337 {
 338         watchdog_softlockup_user_enabled = 0;
 339         return 1;
 340 }
 341 __setup("nosoftlockup", nosoftlockup_setup);
 342
 343 static int __init watchdog_thresh_setup(char *str)
 344 {
 345         get_option(&str, &watchdog_thresh);
 346         return 1;
 347 }
 348 __setup("watchdog_thresh=", watchdog_thresh_setup);
 349
 350 static void __lockup_detector_cleanup(void);
 351
 352 #ifdef CONFIG_SOFTLOCKUP_DETECTOR_INTR_STORM
 353 enum stats_per_group {
 354         STATS_SYSTEM,
 355         STATS_SOFTIRQ,
 356         STATS_HARDIRQ,
 357         STATS_IDLE,
 358         NUM_STATS_PER_GROUP,
 359 };
 360
 361 static const enum cpu_usage_stat tracked_stats[NUM_STATS_PER_GROUP] = {
 362         CPUTIME_SYSTEM,
 363         CPUTIME_SOFTIRQ,
 364         CPUTIME_IRQ,
 365         CPUTIME_IDLE,
 366 };
 367
 368 static DEFINE_PER_CPU(u16, cpustat_old[NUM_STATS_PER_GROUP]);
 369 static DEFINE_PER_CPU(u8, cpustat_util[NUM_SAMPLE_PERIODS][NUM_STATS_PER_GROUP]);
 370 static DEFINE_PER_CPU(u8, cpustat_tail);
 371
 372 /*
 373  * We don't need nanosecond resolution. A granularity of 16ms is
 374  * sufficient for our precision, allowing us to use u16 to store
 375  * cpustats, which will roll over roughly every ~1000 seconds.
 376  * 2^24 ~= 16 * 10^6
 377  */
 378 static u16 get_16bit_precision(u64 data_ns)
 379 {
 380         return data_ns >> 24LL; /* 2^24ns ~= 16.8ms */
 381 }
 382
 383 static void update_cpustat(void)
 384 {
 385         int i;
 386         u8 util;
 387         u16 old_stat, new_stat;
 388         struct kernel_cpustat kcpustat;
 389         u64 *cpustat = kcpustat.cpustat;
 390         u8 tail = __this_cpu_read(cpustat_tail);
 391         u16 sample_period_16 = get_16bit_precision(sample_period);
 392
 393         kcpustat_cpu_fetch(&kcpustat, smp_processor_id());
 394
 395         for (i = 0; i < NUM_STATS_PER_GROUP; i++) {
 396                 old_stat = __this_cpu_read(cpustat_old[i]);
 397                 new_stat = get_16bit_precision(cpustat[tracked_stats[i]]);
 398                 util = DIV_ROUND_UP(100 * (new_stat - old_stat), sample_period_16);
 399                 __this_cpu_write(cpustat_util[tail][i], util);
 400                 __this_cpu_write(cpustat_old[i], new_stat);
 401         }
 402
 403         __this_cpu_write(cpustat_tail, (tail + 1) % NUM_SAMPLE_PERIODS);
 404 }
 405
 406 static void print_cpustat(void)
 407 {
 408         int i, group;
 409         u8 tail = __this_cpu_read(cpustat_tail);
 410         u64 sample_period_second = sample_period;
 411
 412         do_div(sample_period_second, NSEC_PER_SEC);
 413
 414         /*
 415          * Outputting the "watchdog" prefix on every line is redundant and not
 416          * concise, and the original alarm information is sufficient for
 417          * positioning in logs, hence here printk() is used instead of pr_crit().
 418          */
 419         printk(KERN_CRIT "CPU#%d Utilization every %llus during lockup:\n",
 420                smp_processor_id(), sample_period_second);
 421
 422         for (i = 0; i < NUM_SAMPLE_PERIODS; i++) {
 423                 group = (tail + i) % NUM_SAMPLE_PERIODS;
 424                 printk(KERN_CRIT "\t#%d: %3u%% system,\t%3u%% softirq,\t"
 425                         "%3u%% hardirq,\t%3u%% idle\n", i + 1,
 426                         __this_cpu_read(cpustat_util[group][STATS_SYSTEM]),
 427                         __this_cpu_read(cpustat_util[group][STATS_SOFTIRQ]),
 428                         __this_cpu_read(cpustat_util[group][STATS_HARDIRQ]),
 429                         __this_cpu_read(cpustat_util[group][STATS_IDLE]));
 430         }
 431 }
 432
 433 #define HARDIRQ_PERCENT_THRESH          50
 434 #define NUM_HARDIRQ_REPORT              5
 435 struct irq_counts {
 436         int irq;
 437         u32 counts;
 438 };
 439
 440 static DEFINE_PER_CPU(bool, snapshot_taken);
 441
 442 /* Tabulate the most frequent interrupts. */
 443 static void tabulate_irq_count(struct irq_counts *irq_counts, int irq, u32 counts, int rank)
 444 {
 445         int i;
 446         struct irq_counts new_count = {irq, counts};
 447
 448         for (i = 0; i < rank; i++) {
 449                 if (counts > irq_counts[i].counts)
 450                         swap(new_count, irq_counts[i]);
 451         }
 452 }
 453
 454 /*
 455  * If the hardirq time exceeds HARDIRQ_PERCENT_THRESH% of the sample_period,
 456  * then the cause of softlockup might be interrupt storm. In this case, it
 457  * would be useful to start interrupt counting.
 458  */
 459 static bool need_counting_irqs(void)
 460 {
 461         u8 util;
 462         int tail = __this_cpu_read(cpustat_tail);
 463
 464         tail = (tail + NUM_HARDIRQ_REPORT - 1) % NUM_HARDIRQ_REPORT;
 465         util = __this_cpu_read(cpustat_util[tail][STATS_HARDIRQ]);
 466         return util > HARDIRQ_PERCENT_THRESH;
 467 }
 468
 469 static void start_counting_irqs(void)
 470 {
 471         if (!__this_cpu_read(snapshot_taken)) {
 472                 kstat_snapshot_irqs();
 473                 __this_cpu_write(snapshot_taken, true);
 474         }
 475 }
 476
 477 static void stop_counting_irqs(void)
 478 {
 479         __this_cpu_write(snapshot_taken, false);
 480 }
 481
 482 static void print_irq_counts(void)
 483 {
 484         unsigned int i, count;
 485         struct irq_counts irq_counts_sorted[NUM_HARDIRQ_REPORT] = {
 486                 {-1, 0}, {-1, 0}, {-1, 0}, {-1, 0}, {-1, 0}
 487         };
 488
 489         if (__this_cpu_read(snapshot_taken)) {
 490                 for_each_active_irq(i) {
 491                         count = kstat_get_irq_since_snapshot(i);
 492                         tabulate_irq_count(irq_counts_sorted, i, count, NUM_HARDIRQ_REPORT);
 493                 }
 494
 495                 /*
 496                  * Outputting the "watchdog" prefix on every line is redundant and not
 497                  * concise, and the original alarm information is sufficient for
 498                  * positioning in logs, hence here printk() is used instead of pr_crit().
 499                  */
 500                 printk(KERN_CRIT "CPU#%d Detect HardIRQ Time exceeds %d%%. Most frequent HardIRQs:\n",
 501                        smp_processor_id(), HARDIRQ_PERCENT_THRESH);
 502
 503                 for (i = 0; i < NUM_HARDIRQ_REPORT; i++) {
 504                         if (irq_counts_sorted[i].irq == -1)
 505                                 break;
 506
 507                         printk(KERN_CRIT "\t#%u: %-10u\tirq#%d\n",
 508                                i + 1, irq_counts_sorted[i].counts,
 509                                irq_counts_sorted[i].irq);
 510                 }
 511
 512                 /*
 513                  * If the hardirq time is less than HARDIRQ_PERCENT_THRESH% in the last
 514                  * sample_period, then we suspect the interrupt storm might be subsiding.
 515                  */
 516                 if (!need_counting_irqs())
 517                         stop_counting_irqs();
 518         }
 519 }
 520
 521 static void report_cpu_status(void)
 522 {
 523         print_cpustat();
 524         print_irq_counts();
 525 }
 526 #else
 527 static inline void update_cpustat(void) { }
 528 static inline void report_cpu_status(void) { }
 529 static inline bool need_counting_irqs(void) { return false; }
 530 static inline void start_counting_irqs(void) { }
 531 static inline void stop_counting_irqs(void) { }
 532 #endif
 533
 534 /*
 535  * Hard-lockup warnings should be triggered after just a few seconds. Soft-
 536  * lockups can have false positives under extreme conditions. So we generally
 537  * want a higher threshold for soft lockups than for hard lockups. So we couple
 538  * the thresholds with a factor: we make the soft threshold twice the amount of
 539  * time the hard threshold is.
 540  */
 541 static int get_softlockup_thresh(void)
 542 {
 543         return watchdog_thresh * 2;
 544 }
 545
 546 /*
 547  * Returns seconds, approximately.  We don't need nanosecond
 548  * resolution, and we don't need to waste time with a big divide when
 549  * 2^30ns == 1.074s.
 550  */
 551 static unsigned long get_timestamp(void)
 552 {
 553         return running_clock() >> 30LL;  /* 2^30 ~= 10^9 */
 554 }
 555
 556 static void set_sample_period(void)
 557 {
 558         /*
 559          * convert watchdog_thresh from seconds to ns
 560          * the divide by 5 is to give hrtimer several chances (two
 561          * or three with the current relation between the soft
 562          * and hard thresholds) to increment before the
 563          * hardlockup detector generates a warning
 564          */
 565         sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / NUM_SAMPLE_PERIODS);
 566         watchdog_update_hrtimer_threshold(sample_period);
 567 }
 568
 569 static void update_report_ts(void)
 570 {
 571         __this_cpu_write(watchdog_report_ts, get_timestamp());
 572 }
 573
 574 /* Commands for resetting the watchdog */
 575 static void update_touch_ts(void)
 576 {
 577         __this_cpu_write(watchdog_touch_ts, get_timestamp());
 578         update_report_ts();
 579 }
 580
 581 /**
 582  * touch_softlockup_watchdog_sched - touch watchdog on scheduler stalls
 583  *
 584  * Call when the scheduler may have stalled for legitimate reasons
 585  * preventing the watchdog task from executing - e.g. the scheduler
 586  * entering idle state.  This should only be used for scheduler events.
 587  * Use touch_softlockup_watchdog() for everything else.
 588  */
 589 notrace void touch_softlockup_watchdog_sched(void)
 590 {
 591         /*
 592          * Preemption can be enabled.  It doesn't matter which CPU's watchdog
 593          * report period gets restarted here, so use the raw_ operation.
 594          */
 595         raw_cpu_write(watchdog_report_ts, SOFTLOCKUP_DELAY_REPORT);
 596 }
 597
 598 notrace void touch_softlockup_watchdog(void)
 599 {
 600         touch_softlockup_watchdog_sched();
 601         wq_watchdog_touch(raw_smp_processor_id());
 602 }
 603 EXPORT_SYMBOL(touch_softlockup_watchdog);
 604
 605 void touch_all_softlockup_watchdogs(void)
 606 {
 607         int cpu;
 608
 609         /*
 610          * watchdog_mutex cannpt be taken here, as this might be called
 611          * from (soft)interrupt context, so the access to
 612          * watchdog_allowed_cpumask might race with a concurrent update.
 613          *
 614          * The watchdog time stamp can race against a concurrent real
 615          * update as well, the only side effect might be a cycle delay for
 616          * the softlockup check.
 617          */
 618         for_each_cpu(cpu, &watchdog_allowed_mask) {
 619                 per_cpu(watchdog_report_ts, cpu) = SOFTLOCKUP_DELAY_REPORT;
 620                 wq_watchdog_touch(cpu);
 621         }
 622 }
 623
 624 void touch_softlockup_watchdog_sync(void)
 625 {
 626         __this_cpu_write(softlockup_touch_sync, true);
 627         __this_cpu_write(watchdog_report_ts, SOFTLOCKUP_DELAY_REPORT);
 628 }
 629
 630 static int is_softlockup(unsigned long touch_ts,
 631                          unsigned long period_ts,
 632                          unsigned long now)
 633 {
 634         if ((watchdog_enabled & WATCHDOG_SOFTOCKUP_ENABLED) && watchdog_thresh) {
 635                 /*
 636                  * If period_ts has not been updated during a sample_period, then
 637                  * in the subsequent few sample_periods, period_ts might also not
 638                  * be updated, which could indicate a potential softlockup. In
 639                  * this case, if we suspect the cause of the potential softlockup
 640                  * might be interrupt storm, then we need to count the interrupts
 641                  * to find which interrupt is storming.
 642                  */
 643                 if (time_after_eq(now, period_ts + get_softlockup_thresh() / NUM_SAMPLE_PERIODS) &&
 644                     need_counting_irqs())
 645                         start_counting_irqs();
 646
 647                 /* Warn about unreasonable delays. */
 648                 if (time_after(now, period_ts + get_softlockup_thresh()))
 649                         return now - touch_ts;
 650         }
 651         return 0;
 652 }
 653
 654 /* watchdog detector functions */
 655 static DEFINE_PER_CPU(struct completion, softlockup_completion);
 656 static DEFINE_PER_CPU(struct cpu_stop_work, softlockup_stop_work);
 657
 658 /*
 659  * The watchdog feed function - touches the timestamp.
 660  *
 661  * It only runs once every sample_period seconds (4 seconds by
 662  * default) to reset the softlockup timestamp. If this gets delayed
 663  * for more than 2*watchdog_thresh seconds then the debug-printout
 664  * triggers in watchdog_timer_fn().
 665  */
 666 static int softlockup_fn(void *data)
 667 {
 668         update_touch_ts();
 669         stop_counting_irqs();
 670         complete(this_cpu_ptr(&softlockup_completion));
 671
 672         return 0;
 673 }
 674
 675 /* watchdog kicker functions */
 676 static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
 677 {
 678         unsigned long touch_ts, period_ts, now;
 679         struct pt_regs *regs = get_irq_regs();
 680         int duration;
 681         int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace;
 682         unsigned long flags;
 683
 684         if (!watchdog_enabled)
 685                 return HRTIMER_NORESTART;
 686
 687         watchdog_hardlockup_kick();
 688
 689         /* kick the softlockup detector */
 690         if (completion_done(this_cpu_ptr(&softlockup_completion))) {
 691                 reinit_completion(this_cpu_ptr(&softlockup_completion));
 692                 stop_one_cpu_nowait(smp_processor_id(),
 693                                 softlockup_fn, NULL,
 694                                 this_cpu_ptr(&softlockup_stop_work));
 695         }
 696
 697         /* .. and repeat */
 698         hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period));
 699
 700         /*
 701          * Read the current timestamp first. It might become invalid anytime
 702          * when a virtual machine is stopped by the host or when the watchog
 703          * is touched from NMI.
 704          */
 705         now = get_timestamp();
 706         /*
 707          * If a virtual machine is stopped by the host it can look to
 708          * the watchdog like a soft lockup. This function touches the watchdog.
 709          */
 710         kvm_check_and_clear_guest_paused();
 711         /*
 712          * The stored timestamp is comparable with @now only when not touched.
 713          * It might get touched anytime from NMI. Make sure that is_softlockup()
 714          * uses the same (valid) value.
 715          */
 716         period_ts = READ_ONCE(*this_cpu_ptr(&watchdog_report_ts));
 717
 718         update_cpustat();
 719
 720         /* Reset the interval when touched by known problematic code. */
 721         if (period_ts == SOFTLOCKUP_DELAY_REPORT) {
 722                 if (unlikely(__this_cpu_read(softlockup_touch_sync))) {
 723                         /*
 724                          * If the time stamp was touched atomically
 725                          * make sure the scheduler tick is up to date.
 726                          */
 727                         __this_cpu_write(softlockup_touch_sync, false);
 728                         sched_clock_tick();
 729                 }
 730
 731                 update_report_ts();
 732                 return HRTIMER_RESTART;
 733         }
 734
 735         /* Check for a softlockup. */
 736         touch_ts = __this_cpu_read(watchdog_touch_ts);
 737         duration = is_softlockup(touch_ts, period_ts, now);
 738         if (unlikely(duration)) {
 739                 /*
 740                  * Prevent multiple soft-lockup reports if one cpu is already
 741                  * engaged in dumping all cpu back traces.
 742                  */
 743                 if (softlockup_all_cpu_backtrace) {
 744                         if (test_and_set_bit_lock(0, &soft_lockup_nmi_warn))
 745                                 return HRTIMER_RESTART;
 746                 }
 747
 748                 /* Start period for the next softlockup warning. */
 749                 update_report_ts();
 750
 751                 printk_cpu_sync_get_irqsave(flags);
 752                 pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
 753                         smp_processor_id(), duration,
 754                         current->comm, task_pid_nr(current));
 755                 report_cpu_status();
 756                 print_modules();
 757                 print_irqtrace_events(current);
 758                 if (regs)
 759                         show_regs(regs);
 760                 else
 761                         dump_stack();
 762                 printk_cpu_sync_put_irqrestore(flags);
 763
 764                 if (softlockup_all_cpu_backtrace) {
 765                         trigger_allbutcpu_cpu_backtrace(smp_processor_id());
 766                         if (!softlockup_panic)
 767                                 clear_bit_unlock(0, &soft_lockup_nmi_warn);
 768                 }
 769
 770                 add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK);
 771                 if (softlockup_panic)
 772                         panic("softlockup: hung tasks");
 773         }
 774
 775         return HRTIMER_RESTART;
 776 }
 777
 778 static void watchdog_enable(unsigned int cpu)
 779 {
 780         struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer);
 781         struct completion *done = this_cpu_ptr(&softlockup_completion);
 782
 783         WARN_ON_ONCE(cpu != smp_processor_id());
 784
 785         init_completion(done);
 786         complete(done);
 787
 788         /*
 789          * Start the timer first to prevent the hardlockup watchdog triggering
 790          * before the timer has a chance to fire.
 791          */
 792         hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
 793         hrtimer->function = watchdog_timer_fn;
 794         hrtimer_start(hrtimer, ns_to_ktime(sample_period),
 795                       HRTIMER_MODE_REL_PINNED_HARD);
 796
 797         /* Initialize timestamp */
 798         update_touch_ts();
 799         /* Enable the hardlockup detector */
 800         if (watchdog_enabled & WATCHDOG_HARDLOCKUP_ENABLED)
 801                 watchdog_hardlockup_enable(cpu);
 802 }
 803
 804 static void watchdog_disable(unsigned int cpu)
 805 {
 806         struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer);
 807
 808         WARN_ON_ONCE(cpu != smp_processor_id());
 809
 810         /*
 811          * Disable the hardlockup detector first. That prevents that a large
 812          * delay between disabling the timer and disabling the hardlockup
 813          * detector causes a false positive.
 814          */
 815         watchdog_hardlockup_disable(cpu);
 816         hrtimer_cancel(hrtimer);
 817         wait_for_completion(this_cpu_ptr(&softlockup_completion));
 818 }
 819
 820 static int softlockup_stop_fn(void *data)
 821 {
 822         watchdog_disable(smp_processor_id());
 823         return 0;
 824 }
 825
 826 static void softlockup_stop_all(void)
 827 {
 828         int cpu;
 829
 830         if (!softlockup_initialized)
 831                 return;
 832
 833         for_each_cpu(cpu, &watchdog_allowed_mask)
 834                 smp_call_on_cpu(cpu, softlockup_stop_fn, NULL, false);
 835
 836         cpumask_clear(&watchdog_allowed_mask);
 837 }
 838
 839 static int softlockup_start_fn(void *data)
 840 {
 841         watchdog_enable(smp_processor_id());
 842         return 0;
 843 }
 844
 845 static void softlockup_start_all(void)
 846 {
 847         int cpu;
 848
 849         cpumask_copy(&watchdog_allowed_mask, &watchdog_cpumask);
 850         for_each_cpu(cpu, &watchdog_allowed_mask)
 851                 smp_call_on_cpu(cpu, softlockup_start_fn, NULL, false);
 852 }
 853
 854 int lockup_detector_online_cpu(unsigned int cpu)
 855 {
 856         if (cpumask_test_cpu(cpu, &watchdog_allowed_mask))
 857                 watchdog_enable(cpu);
 858         return 0;
 859 }
 860
 861 int lockup_detector_offline_cpu(unsigned int cpu)
 862 {
 863         if (cpumask_test_cpu(cpu, &watchdog_allowed_mask))
 864                 watchdog_disable(cpu);
 865         return 0;
 866 }
 867
 868 static void __lockup_detector_reconfigure(void)
 869 {
 870         cpus_read_lock();
 871         watchdog_hardlockup_stop();
 872
 873         softlockup_stop_all();
 874         set_sample_period();
 875         lockup_detector_update_enable();
 876         if (watchdog_enabled && watchdog_thresh)
 877                 softlockup_start_all();
 878
 879         watchdog_hardlockup_start();
 880         cpus_read_unlock();
 881         /*
 882          * Must be called outside the cpus locked section to prevent
 883          * recursive locking in the perf code.
 884          */
 885         __lockup_detector_cleanup();
 886 }
 887
 888 void lockup_detector_reconfigure(void)
 889 {
 890         mutex_lock(&watchdog_mutex);
 891         __lockup_detector_reconfigure();
 892         mutex_unlock(&watchdog_mutex);
 893 }
 894
 895 /*
 896  * Create the watchdog infrastructure and configure the detector(s).
 897  */
 898 static __init void lockup_detector_setup(void)
 899 {
 900         /*
 901          * If sysctl is off and watchdog got disabled on the command line,
 902          * nothing to do here.
 903          */
 904         lockup_detector_update_enable();
 905
 906         if (!IS_ENABLED(CONFIG_SYSCTL) &&
 907             !(watchdog_enabled && watchdog_thresh))
 908                 return;
 909
 910         mutex_lock(&watchdog_mutex);
 911         __lockup_detector_reconfigure();
 912         softlockup_initialized = true;
 913         mutex_unlock(&watchdog_mutex);
 914 }
 915
 916 #else /* CONFIG_SOFTLOCKUP_DETECTOR */
 917 static void __lockup_detector_reconfigure(void)
 918 {
 919         cpus_read_lock();
 920         watchdog_hardlockup_stop();
 921         lockup_detector_update_enable();
 922         watchdog_hardlockup_start();
 923         cpus_read_unlock();
 924 }
 925 void lockup_detector_reconfigure(void)
 926 {
 927         __lockup_detector_reconfigure();
 928 }
 929 static inline void lockup_detector_setup(void)
 930 {
 931         __lockup_detector_reconfigure();
 932 }
 933 #endif /* !CONFIG_SOFTLOCKUP_DETECTOR */
 934
 935 static void __lockup_detector_cleanup(void)
 936 {
 937         lockdep_assert_held(&watchdog_mutex);
 938         hardlockup_detector_perf_cleanup();
 939 }
 940
 941 /**
 942  * lockup_detector_cleanup - Cleanup after cpu hotplug or sysctl changes
 943  *
 944  * Caller must not hold the cpu hotplug rwsem.
 945  */
 946 void lockup_detector_cleanup(void)
 947 {
 948         mutex_lock(&watchdog_mutex);
 949         __lockup_detector_cleanup();
 950         mutex_unlock(&watchdog_mutex);
 951 }
 952
 953 /**
 954  * lockup_detector_soft_poweroff - Interface to stop lockup detector(s)
 955  *
 956  * Special interface for parisc. It prevents lockup detector warnings from
 957  * the default pm_poweroff() function which busy loops forever.
 958  */
 959 void lockup_detector_soft_poweroff(void)
 960 {
 961         watchdog_enabled = 0;
 962 }
 963
 964 #ifdef CONFIG_SYSCTL
 965
 966 /* Propagate any changes to the watchdog infrastructure */
 967 static void proc_watchdog_update(void)
 968 {
 969         /* Remove impossible cpus to keep sysctl output clean. */
 970         cpumask_and(&watchdog_cpumask, &watchdog_cpumask, cpu_possible_mask);
 971         __lockup_detector_reconfigure();
 972 }
 973
 974 /*
 975  * common function for watchdog, nmi_watchdog and soft_watchdog parameter
 976  *
 977  * caller             | table->data points to            | 'which'
 978  * -------------------|----------------------------------|-------------------------------
 979  * proc_watchdog      | watchdog_user_enabled            | WATCHDOG_HARDLOCKUP_ENABLED |
 980  *                    |                                  | WATCHDOG_SOFTOCKUP_ENABLED
 981  * -------------------|----------------------------------|-------------------------------
 982  * proc_nmi_watchdog  | watchdog_hardlockup_user_enabled | WATCHDOG_HARDLOCKUP_ENABLED
 983  * -------------------|----------------------------------|-------------------------------
 984  * proc_soft_watchdog | watchdog_softlockup_user_enabled | WATCHDOG_SOFTOCKUP_ENABLED
 985  */
 986 static int proc_watchdog_common(int which, struct ctl_table *table, int write,
 987                                 void *buffer, size_t *lenp, loff_t *ppos)
 988 {
 989         int err, old, *param = table->data;
 990
 991         mutex_lock(&watchdog_mutex);
 992
 993         if (!write) {
 994                 /*
 995                  * On read synchronize the userspace interface. This is a
 996                  * racy snapshot.
 997                  */
 998                 *param = (watchdog_enabled & which) != 0;
 999                 err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
1000         } else {
1001                 old = READ_ONCE(*param);
1002                 err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
1003                 if (!err && old != READ_ONCE(*param))
1004                         proc_watchdog_update();
1005         }
1006         mutex_unlock(&watchdog_mutex);
1007         return err;
1008 }
1009
1010 /*
1011  * /proc/sys/kernel/watchdog
1012  */
1013 static int proc_watchdog(struct ctl_table *table, int write,
1014                          void *buffer, size_t *lenp, loff_t *ppos)
1015 {
1016         return proc_watchdog_common(WATCHDOG_HARDLOCKUP_ENABLED |
1017                                     WATCHDOG_SOFTOCKUP_ENABLED,
1018                                     table, write, buffer, lenp, ppos);
1019 }
1020
1021 /*
1022  * /proc/sys/kernel/nmi_watchdog
1023  */
1024 static int proc_nmi_watchdog(struct ctl_table *table, int write,
1025                              void *buffer, size_t *lenp, loff_t *ppos)
1026 {
1027         if (!watchdog_hardlockup_available && write)
1028                 return -ENOTSUPP;
1029         return proc_watchdog_common(WATCHDOG_HARDLOCKUP_ENABLED,
1030                                     table, write, buffer, lenp, ppos);
1031 }
1032
1033 #ifdef CONFIG_SOFTLOCKUP_DETECTOR
1034 /*
1035  * /proc/sys/kernel/soft_watchdog
1036  */
1037 static int proc_soft_watchdog(struct ctl_table *table, int write,
1038                               void *buffer, size_t *lenp, loff_t *ppos)
1039 {
1040         return proc_watchdog_common(WATCHDOG_SOFTOCKUP_ENABLED,
1041                                     table, write, buffer, lenp, ppos);
1042 }
1043 #endif
1044
1045 /*
1046  * /proc/sys/kernel/watchdog_thresh
1047  */
1048 static int proc_watchdog_thresh(struct ctl_table *table, int write,
1049                                 void *buffer, size_t *lenp, loff_t *ppos)
1050 {
1051         int err, old;
1052
1053         mutex_lock(&watchdog_mutex);
1054
1055         old = READ_ONCE(watchdog_thresh);
1056         err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
1057
1058         if (!err && write && old != READ_ONCE(watchdog_thresh))
1059                 proc_watchdog_update();
1060
1061         mutex_unlock(&watchdog_mutex);
1062         return err;
1063 }
1064
1065 /*
1066  * The cpumask is the mask of possible cpus that the watchdog can run
1067  * on, not the mask of cpus it is actually running on.  This allows the
1068  * user to specify a mask that will include cpus that have not yet
1069  * been brought online, if desired.
1070  */
1071 static int proc_watchdog_cpumask(struct ctl_table *table, int write,
1072                                  void *buffer, size_t *lenp, loff_t *ppos)
1073 {
1074         int err;
1075
1076         mutex_lock(&watchdog_mutex);
1077
1078         err = proc_do_large_bitmap(table, write, buffer, lenp, ppos);
1079         if (!err && write)
1080                 proc_watchdog_update();
1081
1082         mutex_unlock(&watchdog_mutex);
1083         return err;
1084 }
1085
1086 static const int sixty = 60;
1087
1088 static struct ctl_table watchdog_sysctls[] = {
1089         {
1090                 .procname       = "watchdog",
1091                 .data           = &watchdog_user_enabled,
1092                 .maxlen         = sizeof(int),
1093                 .mode           = 0644,
1094                 .proc_handler   = proc_watchdog,
1095                 .extra1         = SYSCTL_ZERO,
1096                 .extra2         = SYSCTL_ONE,
1097         },
1098         {
1099                 .procname       = "watchdog_thresh",
1100                 .data           = &watchdog_thresh,
1101                 .maxlen         = sizeof(int),
1102                 .mode           = 0644,
1103                 .proc_handler   = proc_watchdog_thresh,
1104                 .extra1         = SYSCTL_ZERO,
1105                 .extra2         = (void *)&sixty,
1106         },
1107         {
1108                 .procname       = "watchdog_cpumask",
1109                 .data           = &watchdog_cpumask_bits,
1110                 .maxlen         = NR_CPUS,
1111                 .mode           = 0644,
1112                 .proc_handler   = proc_watchdog_cpumask,
1113         },
1114 #ifdef CONFIG_SOFTLOCKUP_DETECTOR
1115         {
1116                 .procname       = "soft_watchdog",
1117                 .data           = &watchdog_softlockup_user_enabled,
1118                 .maxlen         = sizeof(int),
1119                 .mode           = 0644,
1120                 .proc_handler   = proc_soft_watchdog,
1121                 .extra1         = SYSCTL_ZERO,
1122                 .extra2         = SYSCTL_ONE,
1123         },
1124         {
1125                 .procname       = "softlockup_panic",
1126                 .data           = &softlockup_panic,
1127                 .maxlen         = sizeof(int),
1128                 .mode           = 0644,
1129                 .proc_handler   = proc_dointvec_minmax,
1130                 .extra1         = SYSCTL_ZERO,
1131                 .extra2         = SYSCTL_ONE,
1132         },
1133 #ifdef CONFIG_SMP
1134         {
1135                 .procname       = "softlockup_all_cpu_backtrace",
1136                 .data           = &sysctl_softlockup_all_cpu_backtrace,
1137                 .maxlen         = sizeof(int),
1138                 .mode           = 0644,
1139                 .proc_handler   = proc_dointvec_minmax,
1140                 .extra1         = SYSCTL_ZERO,
1141                 .extra2         = SYSCTL_ONE,
1142         },
1143 #endif /* CONFIG_SMP */
1144 #endif
1145 #ifdef CONFIG_HARDLOCKUP_DETECTOR
1146         {
1147                 .procname       = "hardlockup_panic",
1148                 .data           = &hardlockup_panic,
1149                 .maxlen         = sizeof(int),
1150                 .mode           = 0644,
1151                 .proc_handler   = proc_dointvec_minmax,
1152                 .extra1         = SYSCTL_ZERO,
1153                 .extra2         = SYSCTL_ONE,
1154         },
1155 #ifdef CONFIG_SMP
1156         {
1157                 .procname       = "hardlockup_all_cpu_backtrace",
1158                 .data           = &sysctl_hardlockup_all_cpu_backtrace,
1159                 .maxlen         = sizeof(int),
1160                 .mode           = 0644,
1161                 .proc_handler   = proc_dointvec_minmax,
1162                 .extra1         = SYSCTL_ZERO,
1163                 .extra2         = SYSCTL_ONE,
1164         },
1165 #endif /* CONFIG_SMP */
1166 #endif
1167 };
1168
1169 static struct ctl_table watchdog_hardlockup_sysctl[] = {
1170         {
1171                 .procname       = "nmi_watchdog",
1172                 .data           = &watchdog_hardlockup_user_enabled,
1173                 .maxlen         = sizeof(int),
1174                 .mode           = 0444,
1175                 .proc_handler   = proc_nmi_watchdog,
1176                 .extra1         = SYSCTL_ZERO,
1177                 .extra2         = SYSCTL_ONE,
1178         },
1179 };
1180
1181 static void __init watchdog_sysctl_init(void)
1182 {
1183         register_sysctl_init("kernel", watchdog_sysctls);
1184
1185         if (watchdog_hardlockup_available)
1186                 watchdog_hardlockup_sysctl[0].mode = 0644;
1187         register_sysctl_init("kernel", watchdog_hardlockup_sysctl);
1188 }
1189
1190 #else
1191 #define watchdog_sysctl_init() do { } while (0)
1192 #endif /* CONFIG_SYSCTL */
1193
1194 static void __init lockup_detector_delay_init(struct work_struct *work);
1195 static bool allow_lockup_detector_init_retry __initdata;
1196
1197 static struct work_struct detector_work __initdata =
1198                 __WORK_INITIALIZER(detector_work, lockup_detector_delay_init);
1199
1200 static void __init lockup_detector_delay_init(struct work_struct *work)
1201 {
1202         int ret;
1203
1204         ret = watchdog_hardlockup_probe();
1205         if (ret) {
1206                 pr_info("Delayed init of the lockup detector failed: %d\n", ret);
1207                 pr_info("Hard watchdog permanently disabled\n");
1208                 return;
1209         }
1210
1211         allow_lockup_detector_init_retry = false;
1212
1213         watchdog_hardlockup_available = true;
1214         lockup_detector_setup();
1215 }
1216
1217 /*
1218  * lockup_detector_retry_init - retry init lockup detector if possible.
1219  *
1220  * Retry hardlockup detector init. It is useful when it requires some
1221  * functionality that has to be initialized later on a particular
1222  * platform.
1223  */
1224 void __init lockup_detector_retry_init(void)
1225 {
1226         /* Must be called before late init calls */
1227         if (!allow_lockup_detector_init_retry)
1228                 return;
1229
1230         schedule_work(&detector_work);
1231 }
1232
1233 /*
1234  * Ensure that optional delayed hardlockup init is proceed before
1235  * the init code and memory is freed.
1236  */
1237 static int __init lockup_detector_check(void)
1238 {
1239         /* Prevent any later retry. */
1240         allow_lockup_detector_init_retry = false;
1241
1242         /* Make sure no work is pending. */
1243         flush_work(&detector_work);
1244
1245         watchdog_sysctl_init();
1246
1247         return 0;
1248
1249 }
1250 late_initcall_sync(lockup_detector_check);
1251
1252 void __init lockup_detector_init(void)
1253 {
1254         if (tick_nohz_full_enabled())
1255                 pr_info("Disabling watchdog on nohz_full cores by default\n");
1256
1257         cpumask_copy(&watchdog_cpumask,
1258                      housekeeping_cpumask(HK_TYPE_TIMER));
1259
1260         if (!watchdog_hardlockup_probe())
1261                 watchdog_hardlockup_available = true;
1262         else
1263                 allow_lockup_detector_init_retry = true;
1264
1265         lockup_detector_setup();
1266 }