> On 30/05/2022 09:29, Gabriel Moyano wrote:
> > Since pps->capgen is not used in uniprocessor configurations, there is
> > no need to verified if it is equal to zero
> >
> > Update #2349
> > ---
> > cpukit/score/src/kern_tc.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/cpukit/score/src/kern_tc.c b/cpukit/score/src/kern_tc.c
> > index 92739d8edd..897f81511e 100644
> > --- a/cpukit/score/src/kern_tc.c
> > +++ b/cpukit/score/src/kern_tc.c
> > @@ -2165,7 +2165,11 @@ pps_event(struct pps_state *pps, int event)
> > if ((event & pps->ppsparam.mode) == 0)
> > return;
> > /* If the timecounter was wound up underneath us, bail out. */
> > +#if defined(RTEMS_SMP)
> > if (pps->capgen == 0 || pps->capgen !=
> > +#else
> > + if (pps->capgen !=
> > +#endif
> > atomic_load_acq_int(&pps->capth->th_generation))
> > return;
> >
>
> I think this fix is incomplete. What is with:
>
> void
> pps_capture(struct pps_state *pps)
> {
> struct timehands *th;
>
> KASSERT(pps != NULL, ("NULL pps pointer in pps_capture"));
> th = timehands;
> pps->capgen = atomic_load_acq_int(&th->th_generation);
> pps->capth = th;
> #ifdef FFCLOCK
> pps->capffth = fftimehands;
> #endif
> pps->capcount = th->th_counter->tc_get_timecount(th->th_counter);
> atomic_thread_fence_acq();
> if (pps->capgen != th->th_generation)
> pps->capgen = 0;
> }
>
> I don't know why there is this "if" in the code. I will ask on a FreeBSD
> mailing list.
>
I think it is for the case that th_generation has changed in between saving the
th and th_counter. If this happens pps->capgen is set to 0 and later
pps_event() returns earlier. Since for uniprocessor th_generation equal to 0 is
not used, I guess we can removed this if for those configurations
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