linux-kernel - [PATCH v1 1/2] perf auxtrace: Change to use SMP memory barriers

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Date:   Wed, 19 May 2021 22:03:18 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Leo Yan <leo.yan@...aro.org>
Subject: [PATCH v1 1/2] perf auxtrace: Change to use SMP memory barriers

The AUX ring buffer's head and tail can be accessed from multiple CPUs
on SMP system, so changes to use SMP memory barriers to replace the
uniprocessor barriers.

Signed-off-by: Leo Yan <leo.yan@...aro.org>
---
 tools/perf/util/auxtrace.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
index 472c0973b1f1..8bed284ccc82 100644
--- a/tools/perf/util/auxtrace.h
+++ b/tools/perf/util/auxtrace.h
@@ -452,7 +452,7 @@ static inline u64 auxtrace_mmap__read_snapshot_head(struct auxtrace_mmap *mm)
 	u64 head = READ_ONCE(pc->aux_head);
 
 	/* Ensure all reads are done after we read the head */
-	rmb();
+	smp_rmb();
 	return head;
 }
 
@@ -466,7 +466,7 @@ static inline u64 auxtrace_mmap__read_head(struct auxtrace_mmap *mm)
 #endif
 
 	/* Ensure all reads are done after we read the head */
-	rmb();
+	smp_rmb();
 	return head;
 }
 
@@ -478,7 +478,7 @@ static inline void auxtrace_mmap__write_tail(struct auxtrace_mmap *mm, u64 tail)
 #endif
 
 	/* Ensure all reads are done before we write the tail out */
-	mb();
+	smp_mb();
 #if BITS_PER_LONG == 64 || !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
 	pc->aux_tail = tail;
 #else
-- 
2.25.1