From 5d2d548b61f24f9bf5cabaf23b518bc98ece587e Mon Sep 17 00:00:00 2001
From: hselasky <hselasky@ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f>
Date: Mon, 14 Aug 2017 13:15:13 +0000
Subject: [PATCH] MFC r292537 and r314878: Implement ACCESS_ONCE(),
 WRITE_ONCE() and READ_ONCE().

Sponsored by:	Mellanox Technologies


git-svn-id: svn://svn.freebsd.org/base/stable/9@322501 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
---
 sys/ofed/include/linux/compiler.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/sys/ofed/include/linux/compiler.h b/sys/ofed/include/linux/compiler.h
index 9b1a5ad47..194489c1b 100644
--- a/sys/ofed/include/linux/compiler.h
+++ b/sys/ofed/include/linux/compiler.h
@@ -63,4 +63,21 @@
 
 #define	uninitialized_var(x)		x = x
 
+#define	ACCESS_ONCE(x)			(*(volatile __typeof(x) *)&(x))
+  
+#define	WRITE_ONCE(x,v) do {		\
+	barrier();			\
+	ACCESS_ONCE(x) = (v);		\
+	barrier();			\
+} while (0)
+
+#define	READ_ONCE(x) ({			\
+	__typeof(x) __var = ({		\
+		barrier();		\
+		ACCESS_ONCE(x);		\
+	});				\
+	barrier();			\
+	__var;				\
+})
+
 #endif	/* _LINUX_COMPILER_H_ */
-- 
2.42.0