[PATCH] type safe(r) list_entry repacement: container_of

Define container_of which cast from member to struct with some type checking.

This is much like list_entry but is cearly for things other than lists.

List_entry now uses container_of.

1 files changed, 13 insertions, 0 deletions

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 2204760615d8..9fe11d9b6dc4 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -150,6 +150,19 @@ extern const char *print_tainted(void);
 #define max_t(type,x,y) \
 	({ type __x = (x); type __y = (y); __x > __y ? __x: __y; })
 
+
+/**
+ * container_of - cast a member of a structure out to the containing structure
+ *
+ * @ptr:	the pointer to the member.
+ * @type:	the type of the container struct this is embedded in.
+ * @member:	the name of the member within the struct.
+ *
+ */
+#define container_of(ptr, type, member) ({			\
+        const typeof( ((type *)0)->member ) *__mptr = (ptr);	\
+        (type *)( (char *)__mptr - offsetof(type,member) );})
+
 #endif /* __KERNEL__ */
 
 #define SI_LOAD_SHIFT	16