add container_of() macro to osdep.h (Gerd Hoffmann)

From linux kernel sources, xen bits will use it, put it
into a place where others can see and use it too ;)

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>



git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5057 c046a42c-6fe2-441c-8c8c-71466251a162

osdep.h

@@ -23,6 +23,10 @@
 #define unlikely(x)   __builtin_expect(!!(x), 0)
 #endif
 
+#define container_of(ptr, type, member) ({                      \
+        const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
+        (type *)( (char *)__mptr - offsetof(type,member) );})
+
 #ifndef MIN
 #define MIN(a, b) (((a) < (b)) ? (a) : (b))
 #endif