[PATCH] Reduce number of pointer dereferences in IPv6 netfilter LOGmodule function dump_packet()

From: Jesper Juhl
Date: Sun Nov 14 2010 - 16:59:46 EST



By adding two pointer variables to
net/ipv6/netfilter/ip6t_LOG.c::dump_packet() we can save 19 bytes of .text
and many pointer dereferences.

before:
text data bss dec hex filename
6258 600 3088 9946 26da net/ipv6/netfilter/ip6t_LOG.o

after:
text data bss dec hex filename
6239 600 3088 9927 26c7 net/ipv6/netfilter/ip6t_LOG.o


Please Cc me on replies.


Signed-off-by: Jesper Juhl <jj@xxxxxxxxxxxxx>
---
ip6t_LOG.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/net/ipv6/netfilter/ip6t_LOG.c b/net/ipv6/netfilter/ip6t_LOG.c
index 09c8889..51d10a5 100644
--- a/net/ipv6/netfilter/ip6t_LOG.c
+++ b/net/ipv6/netfilter/ip6t_LOG.c
@@ -46,6 +46,8 @@ static void dump_packet(struct sbuff *m,
unsigned int ptr;
unsigned int hdrlen = 0;
unsigned int logflags;
+ struct sock *sk;
+ struct socket *sk_socket;

if (info->type == NF_LOG_TYPE_LOG)
logflags = info->u.log.logflags;
@@ -358,13 +360,15 @@ static void dump_packet(struct sbuff *m,
}

/* Max length: 15 "UID=4294967295 " */
- if ((logflags & IP6T_LOG_UID) && recurse && skb->sk) {
- read_lock_bh(&skb->sk->sk_callback_lock);
- if (skb->sk->sk_socket && skb->sk->sk_socket->file)
+ sk = skb->sk;
+ sk_socket = sk->sk_socket;
+ if ((logflags & IP6T_LOG_UID) && recurse && sk) {
+ read_lock_bh(&sk->sk_callback_lock);
+ if (sk_socket && sk_socket->file)
sb_add(m, "UID=%u GID=%u ",
- skb->sk->sk_socket->file->f_cred->fsuid,
- skb->sk->sk_socket->file->f_cred->fsgid);
- read_unlock_bh(&skb->sk->sk_callback_lock);
+ sk_socket->file->f_cred->fsuid,
+ sk_socket->file->f_cred->fsgid);
+ read_unlock_bh(&sk->sk_callback_lock);
}

/* Max length: 16 "MARK=0xFFFFFFFF " */



--
Jesper Juhl <jj@xxxxxxxxxxxxx> http://www.chaosbits.net/
Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
Plain text mails only, please.

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