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[XFRM]: Pack struct xfrm_policy

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[acme@newtoy net-2.6.20]$ pahole net/ipv4/tcp.o xfrm_policy
/* /pub/scm/linux/kernel/git/acme/net-2.6.20/include/linux/security.h:67 */
struct xfrm_policy {
        struct xfrm_policy *       next;                 /*     0     4 */
        struct hlist_node          bydst;                /*     4     8 */
        struct hlist_node          byidx;                /*    12     8 */
        rwlock_t                   lock;                 /*    20    36 */
        atomic_t                   refcnt;               /*    56     4 */
        struct timer_list          timer;                /*    60    24 */
        u8                         type;                 /*    84     1 */

        /* XXX 3 bytes hole, try to pack */

        u32                        priority;             /*    88     4 */
        u32                        index;                /*    92     4 */
        struct xfrm_selector       selector;             /*    96    56 */
        struct xfrm_lifetime_cfg   lft;                  /*   152    64 */
        struct xfrm_lifetime_cur   curlft;               /*   216    32 */
        struct dst_entry *         bundles;              /*   248     4 */
        __u16                      family;               /*   252     2 */
        __u8                       action;               /*   254     1 */
        __u8                       flags;                /*   255     1 */
        __u8                       dead;                 /*   256     1 */
        __u8                       xfrm_nr;              /*   257     1 */

        /* XXX 2 bytes hole, try to pack */

        struct xfrm_sec_ctx *      security;             /*   260     4 */
        struct xfrm_tmpl           xfrm_vec[6];          /*   264   360 */
}; /* size: 624, sum members: 619, holes: 2, sum holes: 5 */

So lets have just one hole instead of two, by moving 'type' to just before 'action',
end result:

[acme@newtoy net-2.6.20]$ codiff -s /tmp/tcp.o.before net/ipv4/tcp.o
/pub/scm/linux/kernel/git/acme/net-2.6.20/net/ipv4/tcp.c:
  struct xfrm_policy |   -4
 1 struct changed
[acme@newtoy net-2.6.20]$

[acme@newtoy net-2.6.20]$ pahole -c 64 net/ipv4/tcp.o xfrm_policy
/* /pub/scm/linux/kernel/git/acme/net-2.6.20/include/linux/security.h:67 */
struct xfrm_policy {
        struct xfrm_policy *       next;                 /*     0     4 */
        struct hlist_node          bydst;                /*     4     8 */
        struct hlist_node          byidx;                /*    12     8 */
        rwlock_t                   lock;                 /*    20    36 */
        atomic_t                   refcnt;               /*    56     4 */
        struct timer_list          timer;                /*    60    24 */
        u32                        priority;             /*    84     4 */
        u32                        index;                /*    88     4 */
        struct xfrm_selector       selector;             /*    92    56 */
        struct xfrm_lifetime_cfg   lft;                  /*   148    64 */
        struct xfrm_lifetime_cur   curlft;               /*   212    32 */
        struct dst_entry *         bundles;              /*   244     4 */
        u16                        family;               /*   248     2 */
        u8                         type;                 /*   250     1 */
        u8                         action;               /*   251     1 */
        u8                         flags;                /*   252     1 */
        u8                         dead;                 /*   253     1 */
        u8                         xfrm_nr;              /*   254     1 */

        /* XXX 1 byte hole, try to pack */

        struct xfrm_sec_ctx *      security;             /*   256     4 */
        struct xfrm_tmpl           xfrm_vec[6];          /*   260   360 */
}; /* size: 620, sum members: 619, holes: 1, sum holes: 1 */

Are there any fugly data dependencies here? None that I know.

In the process changed the removed the __ prefixed types, that are just for
userspace visible headers.

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This commit is contained in:
Arnaldo Carvalho de Melo 2006-11-27 17:58:59 -02:00 committed by David S. Miller
parent d5c42c0ec4
commit 46ca5f5dc4
1 changed files with 7 additions and 6 deletions
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13
include/net/xfrm.h
View file

@ -340,18 +340,19 @@ struct xfrm_policy
atomic_t refcnt;
struct timer_list timer;
u8 type;
u32 priority;
u32 index;
struct xfrm_selector selector;
struct xfrm_lifetime_cfg lft;
struct xfrm_lifetime_cur curlft;
struct dst_entry *bundles;
__u16 family;
__u8 action;
__u8 flags;
__u8 dead;
__u8 xfrm_nr;
u16 family;
u8 type;
u8 action;
u8 flags;
u8 dead;
u8 xfrm_nr;
/* XXX 1 byte hole, try to pack */
struct xfrm_sec_ctx *security;
struct xfrm_tmpl xfrm_vec[XFRM_MAX_DEPTH];
};