>From fd5fb9afb6b99b15370a9823b42fa2a92342b92a Mon Sep 17 00:00:00 2001
From: Akira Yokosawa <akiyks@xxxxxxxxx>
Date: Sun, 28 May 2017 15:42:45 +0900
Subject: [RFC PATCH 4/4] CodeSamples/defer: Add compiler barriers in gettimestampmp.c
They ensure curtimestamp is read and written once in every
iteration.
Signed-off-by: Akira Yokosawa <akiyks@xxxxxxxxx>
---
CodeSamples/defer/gettimestampmp.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/CodeSamples/defer/gettimestampmp.c b/CodeSamples/defer/gettimestampmp.c
index e794e82..7012caa 100644
--- a/CodeSamples/defer/gettimestampmp.c
+++ b/CodeSamples/defer/gettimestampmp.c
@@ -32,7 +32,7 @@ void *collect_timestamps(void *mask_in)
intptr_t mask = (intptr_t)mask_in;
while (curtimestamp < MAX_TIMESTAMPS) {
- while ((curtimestamp & CURTIMESTAMP_MASK) != mask)
+ while ((READ_ONCE(curtimestamp) & CURTIMESTAMP_MASK) != mask)
continue;
if (curtimestamp >= MAX_TIMESTAMPS)
break;
@@ -40,6 +40,7 @@ void *collect_timestamps(void *mask_in)
/* Don't need memory barrier -- no other shared vars!!! */
ts[curtimestamp++] = get_timestamp();
+ barrier();
}
smp_mb();
return (NULL);
--
2.7.4
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