From 47901dc2c4a3f1f9af453486a005d31fe9b393f0 Mon Sep 17 00:00:00 2001 From: Jan Engelhardt Date: Thu, 9 Jul 2009 23:00:19 +0200 Subject: [PATCH] netfilter: xtables: use memcmp in unconditional check Instead of inspecting each u32/char open-coded, clean up and make use of memcmp. On some arches, memcmp is implemented as assembly or GCC's __builtin_memcmp which can possibly take advantages of known alignment. Signed-off-by: Jan Engelhardt --- net/ipv4/netfilter/arp_tables.c | 10 +++------- net/ipv4/netfilter/ip_tables.c | 11 +++-------- net/ipv6/netfilter/ip6_tables.c | 11 +++-------- 3 files changed, 9 insertions(+), 23 deletions(-) diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index 7505dff..b9f7243 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -341,15 +341,11 @@ unsigned int arpt_do_table(struct sk_buff *skb, } /* All zeroes == unconditional rule. */ -static inline int unconditional(const struct arpt_arp *arp) +static inline bool unconditional(const struct arpt_arp *arp) { - unsigned int i; - - for (i = 0; i < sizeof(*arp)/sizeof(__u32); i++) - if (((__u32 *)arp)[i]) - return 0; + static const struct arpt_arp uncond; - return 1; + return memcmp(arp, &uncond, sizeof(uncond)) == 0; } /* Figures out from what hook each rule can be called: returns 0 if diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index 3856aa3..3431a77 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -190,16 +190,11 @@ get_entry(void *base, unsigned int offset) /* All zeroes == unconditional rule. */ /* Mildly perf critical (only if packet tracing is on) */ -static inline int -unconditional(const struct ipt_ip *ip) +static inline bool unconditional(const struct ipt_ip *ip) { - unsigned int i; + static const struct ipt_ip uncond; - for (i = 0; i < sizeof(*ip)/sizeof(__u32); i++) - if (((__u32 *)ip)[i]) - return 0; - - return 1; + return memcmp(ip, &uncond, sizeof(uncond)) == 0; #undef FWINV } diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c index ced1f2c..1389ad9 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -222,16 +222,11 @@ get_entry(void *base, unsigned int offset) /* All zeroes == unconditional rule. */ /* Mildly perf critical (only if packet tracing is on) */ -static inline int -unconditional(const struct ip6t_ip6 *ipv6) +static inline bool unconditional(const struct ip6t_ip6 *ipv6) { - unsigned int i; - - for (i = 0; i < sizeof(*ipv6); i++) - if (((char *)ipv6)[i]) - break; + static const struct ip6t_ip6 uncond; - return (i == sizeof(*ipv6)); + return memcmp(ipv6, &uncond, sizeof(uncond)) == 0; } #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \ -- 2.7.4