X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=include%2Furcu%2Fcompiler.h;h=0de713adc1a03f4affc48eda0efd03c1b7c1a470;hb=dd8987a4052e51b87d2a399fec8997c5192f362f;hp=827ec1fd6eee0d00d5e863f9268fa89b7ae2d59e;hpb=67988e204d2c471b24cae61f3f8fedb4f9375034;p=userspace-rcu.git

diff --git a/include/urcu/compiler.h b/include/urcu/compiler.h
index 827ec1f..0de713a 100644
--- a/include/urcu/compiler.h
+++ b/include/urcu/compiler.h
@@ -74,6 +74,23 @@
 		(type *)((char *)__ptr - offsetof(type, member));	\
 	})
 
+/*
+ * caa_container_of_check_null - Get the address of an object containing a field.
+ *
+ * @ptr: pointer to the field.
+ * @type: type of the object.
+ * @member: name of the field within the object.
+ *
+ * Return the address of the object containing the field. Return NULL if
+ * @ptr is NULL.
+ */
+#define caa_container_of_check_null(ptr, type, member)			\
+	__extension__							\
+	({								\
+		const __typeof__(((type *) NULL)->member) * __ptr = (ptr); \
+		(__ptr) ? (type *)((char *)__ptr - offsetof(type, member)) : NULL; \
+	})
+
 #define CAA_BUILD_BUG_ON_ZERO(cond) (sizeof(struct { int:-!!(cond); }))
 #define CAA_BUILD_BUG_ON(cond) ((void)CAA_BUILD_BUG_ON_ZERO(cond))
 
@@ -123,30 +140,4 @@
 				+ __GNUC_PATCHLEVEL__)
 #endif
 
-#ifdef __cplusplus
-#define caa_unqual_scalar_typeof(x)					\
-	std::remove_cv<std::remove_reference<decltype(x)>::type>::type
-#else
-#define caa_scalar_type_to_expr(type)					\
-	unsigned type: (unsigned type)0,				\
-	signed type: (signed type)0
-
-/*
- * Use C11 _Generic to express unqualified type from expression. This removes
- * volatile qualifier from expression type.
- */
-#define caa_unqual_scalar_typeof(x)					\
-	__typeof__(							\
-		_Generic((x),						\
-			char: (char)0,					\
-			caa_scalar_type_to_expr(char),			\
-			caa_scalar_type_to_expr(short),		\
-			caa_scalar_type_to_expr(int),			\
-			caa_scalar_type_to_expr(long),			\
-			caa_scalar_type_to_expr(long long),		\
-			default: (x)					\
-		)							\
-	)
-#endif
-
 #endif /* _URCU_COMPILER_H */