Re: [PATCH 1/6] [watchdog] combine nmi_watchdog and softlockup

Frederic Weisbecker
2010-04-21T17:27:31Z

Some minor things:

On Tue, Apr 20, 2010 at 11:23:58AM -0400, Don Zickus wrote:
> +#ifdef CONFIG_PERF_EVENTS_NMI
> +struct perf_event_attr wd_hw_attr = {
> + .type = PERF_TYPE_HARDWARE,
> + .config = PERF_COUNT_HW_CPU_CYCLES,
> + .size = sizeof(struct perf_event_attr),
> + .pinned = 1,
> + .disabled = 1,
> +};

Shouldn't it be static?

> +
> +/* Callback function for perf event subsystem */
> +void watchdog_overflow_callback(struct perf_event *event, int nmi,
> + struct perf_sample_data *data,
> + struct pt_regs *regs)
> +{
> + int this_cpu = smp_processor_id();
> + unsigned long touch_ts = per_cpu(watchdog_touch_ts, this_cpu);
> + char warn = per_cpu(watchdog_warn, this_cpu);

You can use __get_cpu_var() here

> +
> + if (touch_ts == 0) {
> + __touch_watchdog();
> + return;
> + }
> +
> + /* check for a hardlockup
> + * This is done by making sure our timer interrupt
> + * is incrementing. The timer interrupt should have
> + * fired multiple times before we overflow'd. If it hasn't
> + * then this is a good indication the cpu is stuck
> + */
> + if (is_hardlockup(this_cpu)) {
> + /* only print hardlockups once */
> + if (warn & HARDLOCKUP)
> + return;
> +
> + if (hardlockup_panic)
> + panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu);
> + else
> + WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu);
> +
> + per_cpu(watchdog_warn, this_cpu) = warn | HARDLOCKUP;

and here.

> + return;
> + }
> +
> + per_cpu(watchdog_warn, this_cpu) = warn & ~HARDLOCKUP;
> + return;
> +}
> +static void watchdog_interrupt_count(void)
> +{
> + __get_cpu_var(hrtimer_interrupts)++;
> +}
> +#else
> +static void watchdog_interrupt_count(void) { return; }

Off case should be inline (although gcc will probably inline it by itself)

> +#endif /* CONFIG_PERF_EVENTS_NMI */
> +
> +/* watchdog kicker functions */
> +static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
> +{
> + int this_cpu = smp_processor_id();
> + unsigned long touch_ts = per_cpu(watchdog_touch_ts, this_cpu);

__get_cpu_var