3373 gcc >= 4.5 concerns about offsetof()
Portions contributed by: Igor Pashev <pashev.igor@gmail.com>

*** 48,57 ****
--- 48,63 ----
   * Calculate size of a shared ring, given the total available space for the
   * ring and indexes (_sz), and the name tag of the request/response structure.
   * A ring contains as many entries as will fit, rounded down to the nearest
   * power of two (so we can mask with (size-1) to loop around).
   */
+ #define __CONST_RING_SIZE(_s, _sz) \
+     (__RD32(((_sz) - offsetof(struct _s##_sring, ring)) / \
+        sizeof(((struct _s##_sring *)0)->ring[0])))
+ /*
+  * The same for passing in an actual pointer instead of a name tag.
+  */
  #define __RING_SIZE(_s, _sz) \
      (__RD32(((_sz) - (long)(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0])))
  
  /*
   * Macros to make the correct C datatypes for a new kind of ring.