| Message ID | alpine.LNX.2.00.1011142212310.1253@swampdragon.chaosbits.net |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | David Miller |
| Headers | show |
Le dimanche 14 novembre 2010 à 22:35 +0100, Jesper Juhl a écrit : > By adding two pointer variables to > net/ipv4/netfilter/ipt_LOG.c::dump_packet() we can save 16 bytes of .text > and 9 pointer dereferences. > > before this patch we did 20 pointer dereferences and had this object file > size: > text data bss dec hex filename > 6233 600 3080 9913 26b9 net/ipv4/netfilter/ipt_LOG.o > > after this patch we do just 11 pointer dereferences and have this object > file size: > text data bss dec hex filename > 6217 600 3080 9897 26a9 net/ipv4/netfilter/ipt_LOG.o > > > Please Cc me on replies. > > > Signed-off-by: Jesper Juhl <jj@chaosbits.net> > --- > ipt_LOG.c | 16 ++++++++++------ > 1 file changed, 10 insertions(+), 6 deletions(-) > > diff --git a/net/ipv4/netfilter/ipt_LOG.c b/net/ipv4/netfilter/ipt_LOG.c > index 72ffc8f..02a92de 100644 > --- a/net/ipv4/netfilter/ipt_LOG.c > +++ b/net/ipv4/netfilter/ipt_LOG.c > @@ -39,6 +39,8 @@ static void dump_packet(struct sbuff *m, > struct iphdr _iph; > const struct iphdr *ih; > unsigned int logflags; > + struct sock *sk; > + struct socket *sk_socket; > > if (info->type == NF_LOG_TYPE_LOG) > logflags = info->u.log.logflags; > @@ -335,13 +337,15 @@ static void dump_packet(struct sbuff *m, > } > > /* Max length: 15 "UID=4294967295 " */ > - if ((logflags & IPT_LOG_UID) && !iphoff && 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; Really ? sk can be NULL, so you add a NULL dereference. > + if ((logflags & IPT_LOG_UID) && !iphoff && 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 " */ > > > Most of these "dereferences" are compiler optimized. You added a bug in your patch, and make ipt_LOG slower if rule is not asking for IPT_LOG_UID -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/ipv4/netfilter/ipt_LOG.c b/net/ipv4/netfilter/ipt_LOG.c index 72ffc8f..02a92de 100644 --- a/net/ipv4/netfilter/ipt_LOG.c +++ b/net/ipv4/netfilter/ipt_LOG.c @@ -39,6 +39,8 @@ static void dump_packet(struct sbuff *m, struct iphdr _iph; const struct iphdr *ih; unsigned int logflags; + struct sock *sk; + struct socket *sk_socket; if (info->type == NF_LOG_TYPE_LOG) logflags = info->u.log.logflags; @@ -335,13 +337,15 @@ static void dump_packet(struct sbuff *m, } /* Max length: 15 "UID=4294967295 " */ - if ((logflags & IPT_LOG_UID) && !iphoff && 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 & IPT_LOG_UID) && !iphoff && 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 " */
By adding two pointer variables to net/ipv4/netfilter/ipt_LOG.c::dump_packet() we can save 16 bytes of .text and 9 pointer dereferences. before this patch we did 20 pointer dereferences and had this object file size: text data bss dec hex filename 6233 600 3080 9913 26b9 net/ipv4/netfilter/ipt_LOG.o after this patch we do just 11 pointer dereferences and have this object file size: text data bss dec hex filename 6217 600 3080 9897 26a9 net/ipv4/netfilter/ipt_LOG.o Please Cc me on replies. Signed-off-by: Jesper Juhl <jj@chaosbits.net> --- ipt_LOG.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-)