mirror of
https://github.com/torvalds/linux.git
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850db6b8c5
We have a hole in:
[acme@newtoy net-2.6.20]$ pahole net/ipv6/tcp_ipv6.o inet_connection_sock_af_ops
/* /pub/scm/linux/kernel/git/acme/net-2.6.20/include/net/inet_connection_sock.h:38 */
struct inet_connection_sock_af_ops {
int (*queue_xmit)(); /* 0 4 */
void (*send_check)(); /* 4 4 */
int (*rebuild_header)(); /* 8 4 */
int (*conn_request)(); /* 12 4 */
struct sock * (*syn_recv_sock)(); /* 16 4 */
int (*remember_stamp)(); /* 20 4 */
__u16 net_header_len; /* 24 2 */
/* XXX 2 bytes hole, try to pack */
int (*setsockopt)(); /* 28 4 */
int (*getsockopt)(); /* 32 4 */
int (*compat_setsockopt)(); /* 36 4 */
int (*compat_getsockopt)(); /* 40 4 */
void (*addr2sockaddr)(); /* 44 4 */
int sockaddr_len; /* 48 4 */
}; /* size: 52, sum members: 50, holes: 1, sum holes: 2 */
But we don't need sockaddr_len to be an int:
[acme@newtoy net-2.6.20]$ find net -name "*.[ch]" | xargs grep '\.sockaddr_len.\+=' | sort -u
net/dccp/ipv4.c: .sockaddr_len = sizeof(struct sockaddr_in),
net/dccp/ipv6.c: .sockaddr_len = sizeof(struct sockaddr_in6),
net/ipv4/tcp_ipv4.c: .sockaddr_len = sizeof(struct sockaddr_in),
net/ipv6/tcp_ipv6.c: .sockaddr_len = sizeof(struct sockaddr_in6),
net/sctp/ipv6.c: .sockaddr_len = sizeof(struct sockaddr_in6),
net/sctp/protocol.c: .sockaddr_len = sizeof(struct sockaddr_in),
[acme@newtoy net-2.6.20]$ pahole --sizes net/ipv6/tcp_ipv6.o | grep sockaddr_in
struct sockaddr_in: 16 0
struct sockaddr_in6: 28 0
[acme@newtoy net-2.6.20]$
So I turned sockaddr_len a 'u16', and now:
[acme@newtoy net-2.6.20]$ pahole net/ipv6/tcp_ipv6.o inet_connection_sock_af_ops
/* /pub/scm/linux/kernel/git/acme/net-2.6.20/include/net/inet_connection_sock.h:38 */
struct inet_connection_sock_af_ops {
int (*queue_xmit)(); /* 0 4 */
void (*send_check)(); /* 4 4 */
int (*rebuild_header)(); /* 8 4 */
int (*conn_request)(); /* 12 4 */
struct sock * (*syn_recv_sock)(); /* 16 4 */
int (*remember_stamp)(); /* 20 4 */
u16 net_header_len; /* 24 2 */
u16 sockaddr_len; /* 26 2 */
int (*setsockopt)(); /* 28 4 */
int (*getsockopt)(); /* 32 4 */
int (*compat_setsockopt)(); /* 36 4 */
int (*compat_getsockopt)(); /* 40 4 */
void (*addr2sockaddr)(); /* 44 4 */
}; /* size: 48 */
So we've saved 4 bytes:
[acme@newtoy net-2.6.20]$ codiff -sV /tmp/tcp_ipv6.o.before net/ipv6/tcp_ipv6.o
/pub/scm/linux/kernel/git/acme/net-2.6.20/net/ipv6/tcp_ipv6.c:
struct inet_connection_sock_af_ops | -4
net_header_len;
from: __u16 /* 24(0) 2(0) */
to: u16 /* 24(0) 2(0) */
sockaddr_len;
from: int /* 48(0) 4(0) */
to: u16 /* 26(0) 2(0) */
1 struct changed
[acme@newtoy net-2.6.20]$
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
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|---|---|---|
| .. | ||
| bluetooth | ||
| irda | ||
| netfilter | ||
| sctp | ||
| tc_act | ||
| tipc | ||
| act_api.h | ||
| addrconf.h | ||
| af_unix.h | ||
| ah.h | ||
| arp.h | ||
| atmclip.h | ||
| ax25.h | ||
| checksum.h | ||
| cipso_ipv4.h | ||
| compat.h | ||
| datalink.h | ||
| dn_dev.h | ||
| dn_fib.h | ||
| dn_neigh.h | ||
| dn_nsp.h | ||
| dn_route.h | ||
| dn.h | ||
| dsfield.h | ||
| dst.h | ||
| esp.h | ||
| fib_rules.h | ||
| flow.h | ||
| gen_stats.h | ||
| genetlink.h | ||
| icmp.h | ||
| ieee80211_crypt.h | ||
| ieee80211_radiotap.h | ||
| ieee80211.h | ||
| ieee80211softmac_wx.h | ||
| ieee80211softmac.h | ||
| if_inet6.h | ||
| inet_common.h | ||
| inet_connection_sock.h | ||
| inet_ecn.h | ||
| inet_hashtables.h | ||
| inet_sock.h | ||
| inet_timewait_sock.h | ||
| inet6_connection_sock.h | ||
| inet6_hashtables.h | ||
| inetpeer.h | ||
| ip_fib.h | ||
| ip_mp_alg.h | ||
| ip_vs.h | ||
| ip.h | ||
| ip6_checksum.h | ||
| ip6_fib.h | ||
| ip6_route.h | ||
| ip6_tunnel.h | ||
| ipcomp.h | ||
| ipconfig.h | ||
| ipip.h | ||
| ipv6.h | ||
| ipx.h | ||
| iw_handler.h | ||
| lapb.h | ||
| llc_c_ac.h | ||
| llc_c_ev.h | ||
| llc_c_st.h | ||
| llc_conn.h | ||
| llc_if.h | ||
| llc_pdu.h | ||
| llc_s_ac.h | ||
| llc_s_ev.h | ||
| llc_s_st.h | ||
| llc_sap.h | ||
| llc.h | ||
| mip6.h | ||
| ndisc.h | ||
| neighbour.h | ||
| netdma.h | ||
| netevent.h | ||
| netlabel.h | ||
| netlink.h | ||
| netrom.h | ||
| nexthop.h | ||
| p8022.h | ||
| pkt_cls.h | ||
| pkt_sched.h | ||
| protocol.h | ||
| psnap.h | ||
| raw.h | ||
| rawv6.h | ||
| red.h | ||
| request_sock.h | ||
| rose.h | ||
| route.h | ||
| sch_generic.h | ||
| scm.h | ||
| slhc_vj.h | ||
| snmp.h | ||
| sock.h | ||
| syncppp.h | ||
| tcp_ecn.h | ||
| tcp_states.h | ||
| tcp.h | ||
| timewait_sock.h | ||
| transp_v6.h | ||
| udp.h | ||
| udplite.h | ||
| x25.h | ||
| x25device.h | ||
| xfrm.h | ||