The use of memcmp should enable architecture-preferred comparison
methods, for example 64-bit comparisons that would complete in [more
than] half the time than inspecting just each u32/char.
Signed-off-by: Jan Engelhardt <jengelh@xxxxxxxxxx>
---
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) || \
--
1.6.3.3
--
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