cciss: clarify command list padding calculation
cciss: clarify command list padding calculation
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/block/cciss_cmd.h b/drivers/block/cciss_cmd.h
index 25f9762..515c9f0 100644
--- a/drivers/block/cciss_cmd.h
+++ b/drivers/block/cciss_cmd.h
@@ -168,9 +168,14 @@
#define CMD_MSG_STALE 0xff
/* This structure needs to be divisible by 8 for new
- * indexing method.
+ * indexing method. PAD_32 and PAD_64 can be adjusted
+ * independently as needed for 32-bit and 64-bits systems.
*/
-#define PADSIZE (sizeof(long) - 4)
+#define IS_64_BIT ((sizeof(long) - 4)/4)
+#define IS_32_BIT (!IS_64_BIT)
+#define PAD_32 (0)
+#define PAD_64 (4)
+#define PADSIZE (IS_32_BIT * PAD_32 + IS_64_BIT * PAD_64)
typedef struct _CommandList_struct {
CommandListHeader_struct Header;
RequestBlock_struct Request;