[PATCH v4 22/27] compiler: Simple READ/WRITE_ONCE() implementations

[Peter Zijlstra]

Because I need WRITE_ONCE_NOCHECK() and in anticipation of Will's
READ_ONCE rewrite, provide __{READ,WRITE}_ONCE_SCALAR().

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
 include/linux/compiler.h |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -289,6 +289,14 @@ unsigned long read_word_at_a_time(const
 	__u.__val;					\
 })
 
+#define __READ_ONCE_SCALAR(x)			\
+	(*(const volatile typeof(x) *)&(x))
+
+#define __WRITE_ONCE_SCALAR(x, val)		\
+do {						\
+	*(volatile typeof(x) *)&(x) = val;	\
+} while (0)
+
 #endif /* __KERNEL__ */
 
 /*