1 files changed, 3 insertions, 0 deletions
diff --git a/kern/macros.h b/kern/macros.h
index a5b7b032..f3eb1075 100644
--- a/kern/macros.h
+++ b/kern/macros.h
@@ -55,6 +55,9 @@
 #define structof(ptr, type, member) \
     ((type *)((char *)(ptr) - offsetof(type, member)))
 
+#define read_once(x)        (*(volatile typeof(x) *)&(x))
+#define write_once(x, v)    (read_once(x) = (v))
+
 #define alignof(x)          __alignof__(x)
 
 #define likely(expr)        __builtin_expect(!!(expr), 1)