On Thu, 1 Jul 2010, Rafael J. Wysocki wrote:
> > > + if (msec) {
> > > + ktime_t kt;
> > > + struct timespec ts;
> > > + unsigned long expires;
> > > +
> > > + kt = ktime_get();
> > > + kt = ktime_add_ns(kt, msec * NSEC_PER_MSEC);
> > > + ts = ktime_to_timespec(kt);
> > > + expires = timespec_to_jiffies(&ts);
> >
> > Is this somehow better than jiffies + msecs_to_jiffies(msec)?
>
> I'm not sure about overflows. That said, the "+" version is used in many
> places, so there's no problem I think.
Hmm. NSEC_PER_MSEC must be one million, right? So if msec referred to
anything above 4 seconds (which seems unlikely but not impossible), the
multiplication would overflow on a 32-bit machine.
Apart from that, the main difference between the two patches lies in
when the events are counted, i.e., whether event_count gets incremented
at the start or when the timer expires. I can't see that it matters
much either way.
> Index: linux-2.6/drivers/base/power/wakeup.c
> ===================================================================
> --- linux-2.6.orig/drivers/base/power/wakeup.c
> +++ linux-2.6/drivers/base/power/wakeup.c
> @@ -9,6 +9,7 @@
> #include <linux/device.h>
> #include <linux/slab.h>
> #include <linux/sched.h>
> +#include <linux/ktime.h>
This isn't needed any more.
Alan Stern
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