On Fri, 2011-01-14 at 17:02 +0100, Thomas Gleixner wrote: > On Fri, 14 Jan 2011, john stultz wrote: > > > On Fri, 2011-01-14 at 07:44 -0800, john stultz wrote: > > > I'm actually looking at a different fix, as I'm worried by Thomas' > > > comment about hitting the same issue on real hardware if we catch the > > > same pmtrm value both times. > > > > Konrad: Mind trying the following? > > > > > > The conditional (!hpet && !ref_start && !ref_stop) doesn't really make > > sense. If the refs are null, but hpet is on, we still want to break out. > > > > So checking if both the ref values are the same should handle if we > > don't have hardware (both null) or if they are the same value (either by > > invalid hardware, or by chance), which can cause a divzero issue. > > > > NOT FOR INCLUSION, I haven't had my coffee yet. > > Signed-off-by: John Stultz <johnstul@xxxxxxxxxx> > > > > diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c > > index 823f79a..fa2cb5e 100644 > > --- a/arch/x86/kernel/tsc.c > > +++ b/arch/x86/kernel/tsc.c > > @@ -935,7 +935,7 @@ static void tsc_refine_calibration_work(struct work_struct *work) > > tsc_stop = tsc_read_refs(&ref_stop, hpet); > > > > /* hpet or pmtimer available ? */ > > - if (!hpet && !ref_start && !ref_stop) > > + if (ref_start == ref_stop) > > goto out; > > > > /* Check, whether the sampling was disturbed by an SMI */ > > That makes sense, though we really should kill pmtimer when we detect > that it's crappy. Agreed. thanks -john -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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