[PATCH v5 5/9] perf auxtrace: Use WRITE_ONCE() for updating aux_tail

From: Leo Yan
Date: Mon Aug 09 2021 - 07:15:41 EST


Use WRITE_ONCE() for updating aux_tail, so can avoid unexpected memory
behaviour.

Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
tools/perf/util/auxtrace.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
index cc1c1b9cec9c..79227b8864cd 100644
--- a/tools/perf/util/auxtrace.h
+++ b/tools/perf/util/auxtrace.h
@@ -480,7 +480,7 @@ static inline void auxtrace_mmap__write_tail(struct auxtrace_mmap *mm, u64 tail)
/* Ensure all reads are done before we write the tail out */
smp_mb();
#if BITS_PER_LONG == 64 || !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
- pc->aux_tail = tail;
+ WRITE_ONCE(pc->aux_tail, tail);
#else
do {
old_tail = __sync_val_compare_and_swap(&pc->aux_tail, 0, 0);
--
2.25.1