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Use atomic_load(9) to read ppsinfo sequence numbers.

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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
This commit is contained in:
Konstantin Belousov 2017-12-19 10:05:45 +00:00
parent 30d4f9e888
commit 6f697994fd
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=326973
1 changed files with 4 additions and 4 deletions
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8
sys/kern/kern_tc.c
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@ -1601,10 +1601,10 @@ 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,