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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104// SPDX-License-Identifier: GPL-2.0
#include <linux/cpu.h>#include <linux/cpumask.h>#include <linux/kernel.h>#include <linux/nmi.h>#include <linux/percpu-defs.h>
static cpumask_t __read_mostly watchdog_cpus;
static unsigned int watchdog_next_cpu(unsigned int cpu){ unsigned int next_cpu;
next_cpu = cpumask_next_wrap(cpu, &watchdog_cpus); if (next_cpu == cpu) return nr_cpu_ids;
return next_cpu;}
int __init watchdog_hardlockup_probe(void){ watchdog_hardlockup_miss_thresh = 3; return 0;}
void watchdog_hardlockup_enable(unsigned int cpu){ unsigned int next_cpu;
/* * The new CPU will be marked online before the hrtimer interrupt * gets a chance to run on it. If another CPU tests for a * hardlockup on the new CPU before it has run its the hrtimer * interrupt, it will get a false positive. Touch the watchdog on * the new CPU to delay the check for at least 3 sampling periods * to guarantee one hrtimer has run on the new CPU. */ watchdog_hardlockup_touch_cpu(cpu);
/* * We are going to check the next CPU. Our watchdog_hrtimer * need not be zero if the CPU has already been online earlier. * Touch the watchdog on the next CPU to avoid false positive * if we try to check it in less then 3 interrupts. */ next_cpu = watchdog_next_cpu(cpu); if (next_cpu < nr_cpu_ids) watchdog_hardlockup_touch_cpu(next_cpu);
/* * Makes sure that watchdog is touched on this CPU before * other CPUs could see it in watchdog_cpus. The counter * part is in watchdog_buddy_check_hardlockup(). */ smp_wmb();
cpumask_set_cpu(cpu, &watchdog_cpus);}
void watchdog_hardlockup_disable(unsigned int cpu){ unsigned int next_cpu = watchdog_next_cpu(cpu);
/* * Offlining this CPU will cause the CPU before this one to start * checking the one after this one. If this CPU just finished checking * the next CPU and updating hrtimer_interrupts_saved, and then the * previous CPU checks it within one sample period, it will trigger a * false positive. Touch the watchdog on the next CPU to prevent it. */ if (next_cpu < nr_cpu_ids) watchdog_hardlockup_touch_cpu(next_cpu);
/* * Makes sure that watchdog is touched on the next CPU before * this CPU disappear in watchdog_cpus. The counter part is in * watchdog_buddy_check_hardlockup(). */ smp_wmb();
cpumask_clear_cpu(cpu, &watchdog_cpus);}
void watchdog_buddy_check_hardlockup(int hrtimer_interrupts){ unsigned int next_cpu;
/* check for a hardlockup on the next CPU */ next_cpu = watchdog_next_cpu(smp_processor_id()); if (next_cpu >= nr_cpu_ids) return;
/* * Make sure that the watchdog was touched on next CPU when * watchdog_next_cpu() returned another one because of * a change in watchdog_hardlockup_enable()/disable(). */ smp_rmb();
watchdog_hardlockup_check(next_cpu, NULL);}