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Commit c0b8c32b authored by Stephen Hemminger's avatar Stephen Hemminger Committed by David S. Miller
Browse files

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: default avatarStephen Hemminger <shemminger@vyatta.com>
Acked-by: default avatarEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 996b1dba

net/ipv4/route.c

+5 −5
Original line number Diff line number Diff line
@@ -2077,12 +2077,12 @@ int ip_route_input(struct sk_buff *skb, __be32 daddr, __be32 saddr, 
	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);