Re: [RESEND PATCH v4] x86/hpet: Reduce HPET counter read contention

[Waiman Long]

On 08/12/2016 05:20 PM, Dave Hansen wrote:
> On 08/12/2016 02:10 PM, Waiman Long wrote:
> > > I don't think this is right.  If the HPET ever returns the same value
> > > twice in a row (unlikely because it's generally too slow to read, but
> > > it's plausible that someone will make a fast HPET some day), then this
> > > could deadlock.
> > What is the deadlock scenario you are talking about?
> A reader loops waiting for the HPET update by looking for the value to
> change.  If the HPET updater does an update, but the HPET itself hasn't
> advanced, it will write the same value as was there before.  The reader
> will keep looping thinking there was no update.

I should have addressed this problem in my new v5 patch.

Cheers,
Longman