[PATCH 2.4] Backport of container_of macro

From: Hanna Linder (hannal@us.ibm.com)
Date: Mon Nov 11 2002 - 19:16:11 EST


This nifty little macro is used a lot in 2.5 but does not exist
in 2.4 yet. Here is a patch to include it.

Hanna

 kernel.h | 11 +++++++++++
 1 files changed, 11 insertions(+)

diff -Nru linux-2.4.20-rc1/include/linux/kernel.h
linux-container_of/include/linux/kernel.h
--- linux-2.4.20-rc1/include/linux/kernel.h Mon Nov 11 15:23:09 2002
+++ linux-container_of/include/linux/kernel.h Mon Nov 11 15:23:16 2002
@@ -174,6 +174,17 @@
 extern void __out_of_line_bug(int line) ATTRIB_NORET;
 #define out_of_line_bug() __out_of_line_bug(__LINE__)

+/*
+ * 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

-
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