Messages in this thread | | | Date | Thu, 1 Jul 2010 16:44:04 -0400 (EDT) | From | Alan Stern <> | Subject | Re: [update] Re: [PATCH] PM: Make it possible to avoid wakeup events from being lost |
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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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