static DEFINE_PER_CPU(bool, hard_watchdog_warn);
static DEFINE_PER_CPU(bool, watchdog_nmi_touch);
static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);
+#endif
+#ifdef CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU
+static cpumask_t __read_mostly watchdog_cpus;
+#endif
+#ifdef CONFIG_HARDLOCKUP_DETECTOR_NMI
static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
#endif
static unsigned long soft_lockup_nmi_warn;
#ifdef CONFIG_HARDLOCKUP_DETECTOR
unsigned int __read_mostly hardlockup_panic =
CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
-static unsigned long hardlockup_allcpu_dumped;
+static unsigned long __maybe_unused hardlockup_allcpu_dumped;
/*
* We may not want to enable hard lockup detection by default in all cases,
* for example when running the kernel as a guest on a hypervisor. In these
__this_cpu_write(watchdog_touch_ts, 0);
}
-#ifdef CONFIG_HARDLOCKUP_DETECTOR
+#ifdef CONFIG_HARDLOCKUP_DETECTOR_NMI
/* watchdog detector functions */
static bool is_hardlockup(void)
{
}
#endif
+#ifdef CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU
+static unsigned int watchdog_next_cpu(unsigned int cpu)
+{
+ cpumask_t cpus = watchdog_cpus;
+ unsigned int next_cpu;
+
+ next_cpu = cpumask_next(cpu, &cpus);
+ if (next_cpu >= nr_cpu_ids)
+ next_cpu = cpumask_first(&cpus);
+
+ if (next_cpu == cpu)
+ return nr_cpu_ids;
+
+ return next_cpu;
+}
+
+static int is_hardlockup_other_cpu(unsigned int cpu)
+{
+ unsigned long hrint = per_cpu(hrtimer_interrupts, cpu);
+
+ if (per_cpu(hrtimer_interrupts_saved, cpu) == hrint)
+ return 1;
+
+ per_cpu(hrtimer_interrupts_saved, cpu) = hrint;
+ return 0;
+}
+
+static void watchdog_check_hardlockup_other_cpu(void)
+{
+ unsigned int next_cpu;
+
+ /*
+ * Test for hardlockups every 3 samples. The sample period is
+ * watchdog_thresh * 2 / 5, so 3 samples gets us back to slightly over
+ * watchdog_thresh (over by 20%).
+ */
+ if (__this_cpu_read(hrtimer_interrupts) % 3 != 0)
+ return;
+
+ /* check for a hardlockup on the next cpu */
+ next_cpu = watchdog_next_cpu(smp_processor_id());
+ if (next_cpu >= nr_cpu_ids)
+ return;
+
+ smp_rmb();
+
+ if (per_cpu(watchdog_nmi_touch, next_cpu) == true) {
+ per_cpu(watchdog_nmi_touch, next_cpu) = false;
+ return;
+ }
+
+ if (is_hardlockup_other_cpu(next_cpu)) {
+ /* only warn once */
+ if (per_cpu(hard_watchdog_warn, next_cpu) == true)
+ return;
+
+ if (hardlockup_panic)
+ panic("Watchdog detected hard LOCKUP on cpu %u", next_cpu);
+ else
+ WARN(1, "Watchdog detected hard LOCKUP on cpu %u", next_cpu);
+
+ per_cpu(hard_watchdog_warn, next_cpu) = true;
+ } else {
+ per_cpu(hard_watchdog_warn, next_cpu) = false;
+ }
+}
+#else
+static inline void watchdog_check_hardlockup_other_cpu(void) { return; }
+#endif
+
static int is_softlockup(unsigned long touch_ts)
{
unsigned long now = get_timestamp();
return 0;
}
-#ifdef CONFIG_HARDLOCKUP_DETECTOR
+#ifdef CONFIG_HARDLOCKUP_DETECTOR_NMI
static struct perf_event_attr wd_hw_attr = {
.type = PERF_TYPE_HARDWARE,
*/
if (is_hardlockup()) {
int this_cpu = smp_processor_id();
- struct pt_regs *regs = get_irq_regs();
/* only print hardlockups once */
if (__this_cpu_read(hard_watchdog_warn) == true)
__this_cpu_write(hard_watchdog_warn, false);
return;
}
-#endif /* CONFIG_HARDLOCKUP_DETECTOR */
+#endif /* CONFIG_HARDLOCKUP_DETECTOR_NMI */
static void watchdog_interrupt_count(void)
{
/* kick the hardlockup detector */
watchdog_interrupt_count();
+ /* test for hardlockups on the next cpu */
+ watchdog_check_hardlockup_other_cpu();
+
/* kick the softlockup detector */
wake_up_process(__this_cpu_read(softlockup_watchdog));
watchdog_nmi_disable(cpu);
}
-#ifdef CONFIG_HARDLOCKUP_DETECTOR
+#ifdef CONFIG_HARDLOCKUP_DETECTOR_NMI
/*
* People like the simple clean cpu node info on boot.
* Reduce the watchdog noise by only printing messages
}
}
+#else
+#ifdef CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU
+static int watchdog_nmi_enable(unsigned int cpu)
+{
+ /*
+ * The new cpu will be marked online before the first hrtimer interrupt
+ * runs on it. If another cpu tests for a hardlockup on the new cpu
+ * before it has run its first hrtimer, it will get a false positive.
+ * Touch the watchdog on the new cpu to delay the first check for at
+ * least 3 sampling periods to guarantee one hrtimer has run on the new
+ * cpu.
+ */
+ per_cpu(watchdog_nmi_touch, cpu) = true;
+ smp_wmb();
+ cpumask_set_cpu(cpu, &watchdog_cpus);
+ return 0;
+}
+
+static void watchdog_nmi_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)
+ per_cpu(watchdog_nmi_touch, next_cpu) = true;
+ smp_wmb();
+ cpumask_clear_cpu(cpu, &watchdog_cpus);
+}
#else
static int watchdog_nmi_enable(unsigned int cpu) { return 0; }
static void watchdog_nmi_disable(unsigned int cpu) { return; }
-#endif /* CONFIG_HARDLOCKUP_DETECTOR */
+#endif /* CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU */
+#endif /* CONFIG_HARDLOCKUP_DETECTOR_NMI */
static struct smp_hotplug_thread watchdog_threads = {
.store = &softlockup_watchdog,
* both lockup detectors are disabled if proc_watchdog_update()
* returns an error.
*/
+ if (old == new)
+ goto out;
+
err = proc_watchdog_update();
}
out:
int proc_watchdog_thresh(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
- int err, old;
+ int err, old, new;
get_online_cpus();
mutex_lock(&watchdog_proc_mutex);
/*
* Update the sample period. Restore on failure.
*/
+ new = ACCESS_ONCE(watchdog_thresh);
+ if (old == new)
+ goto out;
+
set_sample_period();
err = proc_watchdog_update();
if (err) {
projects / firefly-linux-kernel-4.4.55.git / blobdiff