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From:   Leo Yan <leo.yan@linaro.org>
To:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
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        Namhyung Kim <namhyung@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
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        linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
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Cc:     Leo Yan <leo.yan@linaro.org>
Subject: [PATCH v5 5/9] perf auxtrace: Use WRITE_ONCE() for updating aux_tail
Date:   Mon,  9 Aug 2021 19:14:03 +0800
Message-Id: <20210809111407.596077-6-leo.yan@linaro.org>
In-Reply-To: <20210809111407.596077-1-leo.yan@linaro.org>
References: <20210809111407.596077-1-leo.yan@linaro.org>
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Use WRITE_ONCE() for updating aux_tail, so can avoid unexpected memory
behaviour.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 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