Use local variables for the captured timehand and timecounter in pps_event(). This fixes a potential issue in the nsec preparation for hardpps(). Here the timecounter was accessed through the captured timehand after the generation was checked.
Make a snapshot of the relevent timehand values early in pps_event(). Check the timehand generation only once during the capture and event processing. Use atomic_thread_fence_acq() similar to the other readers. Reviewed by: imp Pull Request: https://github.com/freebsd/freebsd-src/pull/604 --- cpukit/score/src/kern_tc.c | 42 +++++++++++++++++++------------------- 1 file changed, 21 insertions(+), 21 deletions(-) diff --git a/cpukit/score/src/kern_tc.c b/cpukit/score/src/kern_tc.c index eca1a80f33..99abd652d8 100644 --- a/cpukit/score/src/kern_tc.c +++ b/cpukit/score/src/kern_tc.c @@ -2152,16 +2152,14 @@ pps_capture(struct pps_state *pps) #endif tc = th->th_counter; pps->capcount = tc->tc_get_timecount(tc); -#if defined(RTEMS_SMP) - atomic_thread_fence_acq(); - if (pps->capgen != th->th_generation) - pps->capgen = 0; -#endif } void pps_event(struct pps_state *pps, int event) { + struct timehands *capth; + struct timecounter *captc; + uint64_t capth_scale; struct bintime bt; struct timespec ts, *tsp, *osp; uint32_t tcount, *pcount; @@ -2180,13 +2178,21 @@ pps_event(struct pps_state *pps, int event) /* Nothing to do if not currently set to capture this event type. */ if ((event & pps->ppsparam.mode) == 0) return; + + /* Make a snapshot of the captured timehand */ + capth = pps->capth; + captc = capth->th_counter; + capth_scale = capth->th_scale; + tcount = capth->th_offset_count; + bt = capth->th_bintime; + /* If the timecounter was wound up underneath us, bail out. */ + atomic_thread_fence_acq(); #if defined(RTEMS_SMP) - if (pps->capgen == 0 || pps->capgen != + if (pps->capgen == 0 || pps->capgen != capth->th_generation) #else - if (pps->capgen != + if (pps->capgen != capth->th_generation) #endif - atomic_load_acq_int(&pps->capth->th_generation)) return; /* Things would be easier with arrays. */ @@ -2224,25 +2230,19 @@ pps_event(struct pps_state *pps, int event) * If the timecounter changed, we cannot compare the count values, so * we have to drop the rest of the PPS-stuff until the next event. */ - if (pps->ppstc != pps->capth->th_counter) { - pps->ppstc = pps->capth->th_counter; + if (__predict_false(pps->ppstc != captc)) { + pps->ppstc = captc; *pcount = pps->capcount; pps->ppscount[2] = pps->capcount; return; } /* Convert the count to a timespec. */ - tcount = pps->capcount - pps->capth->th_offset_count; - tcount &= pps->capth->th_counter->tc_counter_mask; - bt = pps->capth->th_bintime; - bintime_addx(&bt, pps->capth->th_scale * tcount); + tcount = pps->capcount - tcount; + tcount &= captc->tc_counter_mask; + bintime_addx(&bt, capth_scale * tcount); bintime2timespec(&bt, &ts); - /* If the timecounter was wound up underneath us, bail out. */ - atomic_thread_fence_acq(); - if (pps->capgen != pps->capth->th_generation) - return; - *pcount = pps->capcount; (*pseq)++; *tsp = ts; @@ -2276,9 +2276,9 @@ pps_event(struct pps_state *pps, int event) */ tcount = pps->capcount - pps->ppscount[2]; pps->ppscount[2] = pps->capcount; - tcount &= pps->capth->th_counter->tc_counter_mask; + tcount &= captc->tc_counter_mask; scale = (uint64_t)1 << 63; - scale /= pps->capth->th_counter->tc_frequency; + scale /= captc->tc_frequency; scale *= 2; bt.sec = 0; bt.frac = 0; -- 2.35.3 _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
