+// SPDX-License-Identifier: GPL-2.0
/*
* Detect hard lockups on a system
*
#define pr_fmt(fmt) "NMI watchdog: " fmt
#include <linux/nmi.h>
+#include <linux/atomic.h>
#include <linux/module.h>
#include <linux/sched/debug.h>
static DEFINE_PER_CPU(bool, hard_watchdog_warn);
static DEFINE_PER_CPU(bool, watchdog_nmi_touch);
static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
+static DEFINE_PER_CPU(struct perf_event *, dead_event);
static struct cpumask dead_events_mask;
static unsigned long hardlockup_allcpu_dumped;
-static unsigned int watchdog_cpus;
+static atomic_t watchdog_cpus = ATOMIC_INIT(0);
void arch_touch_nmi_watchdog(void)
{
if (hardlockup_detector_event_create())
return;
- if (!watchdog_cpus++)
+ /* use original value for check */
+ if (!atomic_fetch_inc(&watchdog_cpus))
pr_info("Enabled. Permanently consumes one hw-PMU counter.\n");
perf_event_enable(this_cpu_read(watchdog_ev));
if (event) {
perf_event_disable(event);
+ this_cpu_write(watchdog_ev, NULL);
+ this_cpu_write(dead_event, event);
cpumask_set_cpu(smp_processor_id(), &dead_events_mask);
- watchdog_cpus--;
+ atomic_dec(&watchdog_cpus);
}
}
int cpu;
for_each_cpu(cpu, &dead_events_mask) {
- struct perf_event *event = per_cpu(watchdog_ev, cpu);
+ struct perf_event *event = per_cpu(dead_event, cpu);
/*
* Required because for_each_cpu() reports unconditionally
*/
if (event)
perf_event_release_kernel(event);
- per_cpu(watchdog_ev, cpu) = NULL;
+ per_cpu(dead_event, cpu) = NULL;
}
cpumask_clear(&dead_events_mask);
}