IPV4: use xor rather than multiple ands for route compare
The comparison in ip_route_input is a hot path, by recoding the C
"and" as bit operations, fewer conditional branches get generated
so the code should be faster. Maybe someday Gcc will be smart
enough to do this?
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index a1c5b8d..139799f 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2077,12 +2077,12 @@
rcu_read_lock();
for (rth = rcu_dereference(rt_hash_table[hash].chain); rth;
rth = rcu_dereference(rth->u.dst.rt_next)) {
- if (rth->fl.fl4_dst == daddr &&
- rth->fl.fl4_src == saddr &&
- rth->fl.iif == iif &&
- rth->fl.oif == 0 &&
+ if (((rth->fl.fl4_dst ^ daddr) |
+ (rth->fl.fl4_src ^ saddr) |
+ (rth->fl.iif ^ iif) |
+ rth->fl.oif |
+ (rth->fl.fl4_tos ^ tos)) == 0 &&
rth->fl.mark == skb->mark &&
- rth->fl.fl4_tos == tos &&
net_eq(dev_net(rth->u.dst.dev), net) &&
rth->rt_genid == atomic_read(&rt_genid)) {
dst_use(&rth->u.dst, jiffies);