Re: [PATCH 2/4] watchdog/softlockup: Replace "watchdog/%u" threads with cpu_stop_work

From: Peter Zijlstra
Date: Thu Jun 07 2018 - 10:43:02 EST


On Thu, Jun 07, 2018 at 04:24:05PM +0200, Peter Zijlstra wrote:
> On Thu, Jun 07, 2018 at 02:33:12PM +0200, Peter Zijlstra wrote:
>
> > +static int softlockup_stop_fn(void *data)
> > {
> > + watchdog_disable(smp_processor_id());
> > + return 0;
> > }
> >
> > +static void softlockup_stop_all(void)
> > {
> > + int cpu;
> > +
> > + for_each_cpu(cpu, &watchdog_allowed_mask)
> > + stop_one_cpu(cpu, softlockup_stop_fn, NULL);
> > +
> > + cpumask_clear(&watchdog_allowed_mask);
> > }
>
> Bugger, that one doesn't quite work.. watchdog_disable() ends up calling
> a sleeping function. I forgot to enable all the debug cruft when
> testing..
>
> Let me try and fix that..

The below seems to fix that, and now I can complete all the tests
without triggering debug nonsense ;-)


--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -512,7 +512,7 @@ static void softlockup_stop_all(void)
int cpu;

for_each_cpu(cpu, &watchdog_allowed_mask)
- stop_one_cpu(cpu, softlockup_stop_fn, NULL);
+ smp_call_on_cpu(cpu, softlockup_stop_fn, NULL, false);

cpumask_clear(&watchdog_allowed_mask);
}
@@ -529,7 +529,7 @@ static void softlockup_start_all(void)

cpumask_copy(&watchdog_allowed_mask, &watchdog_cpumask);
for_each_cpu(cpu, &watchdog_allowed_mask)
- stop_one_cpu(cpu, softlockup_start_fn, NULL);
+ smp_call_on_cpu(cpu, softlockup_start_fn, NULL, false);
}

int lockup_detector_online_cpu(unsigned int cpu)