ipv4: Introduce IN_DEV_NET_ROUTE_LOCALNET

performance profiles show a high cost in the IN_DEV_ROUTE_LOCALNET()
call done in ip_route_input_slow(), because of multiple dereferences,
even if cache lines are clean and available in cpu caches.

Since we already have the 'net' pointer, introduce
IN_DEV_NET_ROUTE_LOCALNET() macro avoiding two dereferences
(dev_net(in_dev->dev))

Also change the tests to use IN_DEV_NET_ROUTE_LOCALNET() only if saddr
or/and daddr are loopback addresse.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 4 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index e4ba974f143c..21ad369014c0 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1587,11 +1587,14 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
         if (ipv4_is_zeronet(daddr))
                 goto martian_destination;
 
-        if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev))) {
-                if (ipv4_is_loopback(daddr))
+        /* Following code try to avoid calling IN_DEV_NET_ROUTE_LOCALNET(),
+         * and call it once if daddr or/and saddr are loopback addresses
+         */
+        if (ipv4_is_loopback(daddr)) {
+                if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
                         goto martian_destination;
-
-                if (ipv4_is_loopback(saddr))
+        } else if (ipv4_is_loopback(saddr)) {
+                if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
                         goto martian_source;
         }