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 <jengelh@medozas.de>

1 files changed, 3 insertions, 8 deletions

diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index ced1f2c0cb65..1389ad904bc3 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) || \