On Fri, Apr 16, 2021 at 10:10:51PM +0200, Thomas Gleixner wrote:
> On Tue, Apr 13 2021 at 21:35, Paul E. McKenney wrote:
> >
> > +static int inject_delay_freq;
> > +module_param(inject_delay_freq, int, 0644);
> > +static int inject_delay_run = 1;
> > +module_param(inject_delay_run, int, 0644);
>
> int? Can't we just make them 'unsigned int'? Negative values are not
> that useful.
>
> > +static int max_read_retries = 3;
> > +module_param(max_read_retries, int, 0644);
>
> max_read_retries is unused here. Should be in the patch which actually
> uses it.
Good point, I will make all three unsigned int and move max_read_retries
to 2/5 ("clocksource: Retry clock read if long delays detected").
> > +static void clocksource_watchdog_inject_delay(void)
> > +{
> > + int i;
> > + static int injectfail = -1;
> > +
> > + if (inject_delay_freq <= 0 || inject_delay_run <= 0)
> > + return;
> > + if (injectfail < 0 || injectfail > INT_MAX / 2)
> > + injectfail = inject_delay_run;
> > + if (!(++injectfail / inject_delay_run % inject_delay_freq)) {
>
> Operator precedence based cleverness is really easy to parse - NOT!
>
> > + pr_warn("%s(): Injecting delay.\n", __func__);
> > + for (i = 0; i < 2 * WATCHDOG_THRESHOLD / NSEC_PER_MSEC; i++)
> > + udelay(1000);
> > + pr_warn("%s(): Done injecting delay.\n", __func__);
> > + }
> > +
> > + WARN_ON_ONCE(injectfail < 0);
> > +}
>
> Brain melt stage reached by now.
>
> static unsigned int invocations, injections;
>
> if (!inject_delay_period || !inject_delay_repeat)
> return;
>
> if (!(invocations % inject_delay_period)) {
> mdelay(2 * WATCHDOG_THRESHOLD / NSEC_PER_MSEC);
> if (++injections < inject_delay_repeat)
> return;
> injections = 0;
> }
>
> invocations++;
> }
>
> Hmm?
That is quite a bit nicer than the interacting parameters that I
had. I will rework along these lines.
Thanx, Paul
