[KERNEL]: Add typecheck macro for verifying types at compile time.

include/linux/kernel.h

@@ -188,6 +188,17 @@ extern void dump_stack(void);
         const typeof( ((type *)0)->member ) *__mptr = (ptr);	\
         (type *)( (char *)__mptr - offsetof(type,member) );})
 
+/*
+ * Check at compile time that something is of a particular type.
+ * Always evaluates to 1 so you may use it easily in conparisons.
+ */
+#define typecheck(type,x) \
+({	type __dummy; \
+	typeof(x) __dummy2; \
+	(void)(&__dummy == &__dummy2); \
+	1; \
+})
+
 #endif /* __KERNEL__ */
 
 #define SI_LOAD_SHIFT	16