[PATCH v3 19/22] compiler: Simple READ/WRITE_ONCE() implementations

Peter Zijlstra
2020-02-19T15:14:42Z

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@infradead.org>
---
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__ */

/*