From: Waiman Long <Waiman.Long@xxxxxx> 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit a767f680e34bf14a36fefbbb6d85783eef99fd57 upstream. Currently, the ebitmap_node structure has a fixed size of 32 bytes. On a 32-bit system, the overhead is 8 bytes, leaving 24 bytes for being used as bitmaps. The overhead ratio is 1/4. On a 64-bit system, the overhead is 16 bytes. Therefore, only 16 bytes are left for bitmap purpose and the overhead ratio is 1/2. With a 3.8.2 kernel, a boot-up operation will cause the ebitmap_get_bit() function to be called about 9 million times. The average number of ebitmap_node traversal is about 3.7. This patch increases the size of the ebitmap_node structure to 64 bytes for 64-bit system to keep the overhead ratio at 1/4. This may also improve performance a little bit by making node to node traversal less frequent (< 2) as more bits are available in each node. Signed-off-by: Waiman Long <Waiman.Long@xxxxxx> Acked-by: Stephen Smalley <sds@xxxxxxxxxxxxx> Signed-off-by: Paul Moore <pmoore@xxxxxxxxxx> Signed-off-by: Eric Paris <eparis@xxxxxxxxxx> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> --- security/selinux/ss/ebitmap.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/security/selinux/ss/ebitmap.h b/security/selinux/ss/ebitmap.h index e7eb3a9c5ab7..712c8a7b8e8b 100644 --- a/security/selinux/ss/ebitmap.h +++ b/security/selinux/ss/ebitmap.h @@ -16,7 +16,13 @@ #include <net/netlabel.h> -#define EBITMAP_UNIT_NUMS ((32 - sizeof(void *) - sizeof(u32)) \ +#ifdef CONFIG_64BIT +#define EBITMAP_NODE_SIZE 64 +#else +#define EBITMAP_NODE_SIZE 32 +#endif + +#define EBITMAP_UNIT_NUMS ((EBITMAP_NODE_SIZE-sizeof(void *)-sizeof(u32))\ / sizeof(unsigned long)) #define EBITMAP_UNIT_SIZE BITS_PER_LONG #define EBITMAP_SIZE (EBITMAP_UNIT_NUMS * EBITMAP_UNIT_SIZE) -- 1.9.0 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html