Add a mfence to opal_atomic_mb() for x86.

awlauria · awlauria · commit 8dca246bd515 · 2021-07-08T13:19:59.000-04:00
x86 requires a mfence for it to be a full memory barrier;
a compiler MB is not sufficient.

Co-authored-by: George Katevenis &lt;george_kate@hotmail.com&gt;

Signed-off-by: Austen Lauria &lt;awlauria@us.ibm.com&gt;
diff --git a/opal/include/opal/sys/x86_64/atomic.h b/opal/include/opal/sys/x86_64/atomic.h
@@ -52,7 +52,7 @@
 
 static inline void opal_atomic_mb(void)
 {
-    MB();
+    __asm__ __volatile__("mfence": : :"memory");
 }
 
 static inline void opal_atomic_rmb(void)

Original file line number	Diff line number	Diff line change
`@@ -52,7 +52,7 @@`
`52`	`52`
`53`	`53`	`static inline void opal_atomic_mb(void)`
`54`	`54`	`{`
`55`		`- MB();`
	`55`	`+ __asm__ __volatile__("mfence": : :"memory");`
`56`	`56`	`}`
`57`	`57`
`58`	`58`	`static inline void opal_atomic_rmb(void)`