[PATCH 03/27] Use atomic_load(9) to read ppsinfo sequence numbers.
Moyano, Gabriel
gabriel.moyano at dlr.de
Wed Nov 17 07:50:15 UTC 2021
From: Konstantin Belousov <kib at FreeBSD.org>
In this case volatile qualifiers enusre that a compiler does not
optimize the accesses out.
Reviewed by: alc, jhb
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D13534
---
cpukit/score/src/kern_tc.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/cpukit/score/src/kern_tc.c b/cpukit/score/src/kern_tc.c
index b17327a2f8..9e6602e478 100644
--- a/cpukit/score/src/kern_tc.c
+++ b/cpukit/score/src/kern_tc.c
@@ -1799,10 +1799,10 @@ pps_fetch(struct pps_fetch_args *fapi, struct pps_state *pps)
tv.tv_usec = fapi->timeout.tv_nsec / 1000;
timo = tvtohz(&tv);
}
- aseq = pps->ppsinfo.assert_sequence;
- cseq = pps->ppsinfo.clear_sequence;
- while (aseq == pps->ppsinfo.assert_sequence &&
- cseq == pps->ppsinfo.clear_sequence) {
+ aseq = atomic_load_int(&pps->ppsinfo.assert_sequence);
+ cseq = atomic_load_int(&pps->ppsinfo.clear_sequence);
+ while (aseq == atomic_load_int(&pps->ppsinfo.assert_sequence) &&
+ cseq == atomic_load_int(&pps->ppsinfo.clear_sequence)) {
if (abi_aware(pps, 1) && pps->driver_mtx != NULL) {
if (pps->flags & PPSFLAG_MTX_SPIN) {
err = msleep_spin(pps, pps->driver_mtx,
--
2.17.1
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