svn commit: r322501 - stable/9/sys/ofed/include/linux

[Hans Petter Selasky]

Author: hselasky
Date: Mon Aug 14 13:15:13 2017
New Revision: 322501
URL: https://svnweb.freebsd.org/changeset/base/322501

Log:
  MFC r292537 and r314878:
  Implement ACCESS_ONCE(), WRITE_ONCE() and READ_ONCE().
  
  Sponsored by:	Mellanox Technologies

Modified:
  stable/9/sys/ofed/include/linux/compiler.h
Directory Properties:
  stable/9/sys/   (props changed)

Modified: stable/9/sys/ofed/include/linux/compiler.h
==============================================================================
--- stable/9/sys/ofed/include/linux/compiler.h	Mon Aug 14 12:59:14 2017	(r322500)
+++ stable/9/sys/ofed/include/linux/compiler.h	Mon Aug 14 13:15:13 2017	(r322501)
@@ -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_ */