On Fri, Apr 02 2021 at 15:49, paulmck wrote: > This commit therefore re-reads the watchdog clock on either side of
'This commit' is not any better than 'This patch' and this sentence makes no sense. I might be missing something, but how exactly does "the commit" re-read the watchdog clock? git grep 'This patch' Documentation/process/ > the read from the clock under test. If the watchdog clock shows an > +retry: > local_irq_disable(); > - csnow = cs->read(cs); > - clocksource_watchdog_inject_delay(); > wdnow = watchdog->read(watchdog); > + clocksource_watchdog_inject_delay(); > + csnow = cs->read(cs); > + wdagain = watchdog->read(watchdog); > local_irq_enable(); > + delta = clocksource_delta(wdagain, wdnow, watchdog->mask); > + wdagain_nsec = clocksource_cyc2ns(delta, watchdog->mult, > watchdog->shift); That variable naming is confusing as hell. This is about the delta and not about the second readout of the watchdog. > + if (wdagain_nsec < 0 || wdagain_nsec > WATCHDOG_MAX_SKEW) { How exactly is this going negative especially with clocksources which have a limited bitwidth? See clocksource_delta(). > + wderr_nsec = wdagain_nsec; > + if (nretries++ < max_read_retries) > + goto retry; > + } > + if (nretries) > + pr_warn("timekeeping watchdog on CPU%d: %s read-back > delay of %lldns, attempt %d\n", > + smp_processor_id(), watchdog->name, wderr_nsec, > nretries); Lacks curly braces around the pr_warn() simply because it's not a single line. Breaks my parser :) But if this ever happens to exceed max_read_retries, then what's the point of continuing at all? The data is known to be crap already. > /* Clocksource initialized ? */ > if (!(cs->flags & CLOCK_SOURCE_WATCHDOG) || Thanks, tglx