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

Don Zickus
2010-04-21T17:51:13Z

On Wed, Apr 21, 2010 at 07:27:33PM +0200, Frederic Weisbecker wrote:
> 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?

yes. thanks.

>
>
> > +
> > +/* 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

well, I already have this_cpu and need it later, I figured I would just
use it with per_cpu and save _get_cpu_var the work of re-running
smp_processor_id().

>
>
>
> > +
> > + 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.

same arguement as above.

>
>
>
> > + 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)

yup. thanks.

>
>
>
> > +#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

again same as above.

Thanks for the review.

Cheers,
Don