#include "config.h"
#include "check_type/check_type.h"
+/**
+ * container_of - get pointer to enclosing structure
+ * @member_ptr: pointer to the structure member
+ * @containing_type: the type this member is within
+ * @member: the name of this member within the structure.
+ *
+ * Given a pointer to a member of a structure, this macro does pointer
+ * subtraction to return the pointer to the enclosing type.
+ *
+ * Example:
+ * struct info
+ * {
+ * int some_other_field;
+ * struct foo my_foo;
+ * };
+ *
+ * struct info *foo_to_info(struct foo *foop)
+ * {
+ * return container_of(foo, struct info, my_foo);
+ * }
+ */
#define container_of(member_ptr, containing_type, member) \
((containing_type *) \
((char *)(member_ptr) - offsetof(containing_type, member)) \
- check_types_match(*(member_ptr), ((containing_type *)0)->member))
+/**
+ * container_of_var - get pointer to enclosing structure using a variable
+ * @member_ptr: pointer to the structure member
+ * @var: a pointer to a structure of same type as this member is within
+ * @member: the name of this member within the structure.
+ *
+ * Given a pointer to a member of a structure, this macro does pointer
+ * subtraction to return the pointer to the enclosing type.
+ *
+ * Example:
+ * struct info
+ * {
+ * int some_other_field;
+ * struct foo my_foo;
+ * };
+ *
+ * struct info *foo_to_info(struct foo *foop)
+ * {
+ * struct info *i = container_of_var(foo, i, my_foo);
+ * return i;
+ * }
+ */
+#ifdef HAVE_TYPEOF
+#define container_of_var(member_ptr, var, member) \
+ container_of(member_ptr, typeof(*var), member)
+#else
+#define container_of_var(member_ptr, var, member) \
+ ((void *)((char *)(member_ptr) - offsetof(containing_type, member)))
+#endif
+
#endif /* CCAN_CONTAINER_OF_H */