On Wed, 29 Oct 2014, Arnd Bergmann wrote:
> On Wednesday 29 October 2014 10:21:18 Thomas Gleixner wrote:
> > On Wed, 29 Oct 2014, Heena Sirwani wrote:
> > > +time64_t ktime_get_seconds(void)
> > > +{
> > > + time64_t seconds;
> > > + struct timekeeper *tk = &tk_core.timekeeper;
> > > + unsigned int seq;
> > > +
> > > + WARN_ON(timekeeping_suspended);
> >
> > You want to have the same 64bit logic as you did for
> > ktime_get_real_seconds. So on 64bit it boils down to return
> > tk->ktime_sec.
> >
> > > +
> > > + do {
> > > + seq = read_seqcount_begin(&tk_core.seq);
> > > + seconds = tk->ktime_sec;
> > > +
> > > + } while (read_seqcount_retry(&tk_core.seq, seq));
> >
>
> I wonder if we should just make tk->ktime_sec 'unsigned long' and
> avoid the lock for 32-bit as well. Are there any theoretical
> cases where the monotonic time could overflow a 32-bit integer?
136 years uptime :) I think we discussed that 32bit thing before, but
I forgot again.
> As a minor optimization 's64 nsec_offset' could also be 'long',
> since that only stores a number that is known to be less than
> 1000000000.
Indeed.
Thanks,
tglx
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