ipv4: Optimize flow initialization in input route lookup.

Like in commit 44713b67db10c774f14280c129b0d5fd13c70cf2
("ipv4: Optimize flow initialization in output route lookup."
we can optimize the on-stack flow setup to only initialize
the members which are actually used.

Otherwise we bzero the entire structure, then initialize
explicitly the first half of it.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 6 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 92a24ea34c1b..ac32d8f3d68f 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2081,12 +2081,7 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 {
         struct fib_result res;
         struct in_device *in_dev = __in_dev_get_rcu(dev);
-        struct flowi fl = { .fl4_dst    = daddr,
-                            .fl4_src    = saddr,
-                            .fl4_tos    = tos,
-                            .fl4_scope  = RT_SCOPE_UNIVERSE,
-                            .mark = skb->mark,
-                            .iif = dev->ifindex };
+        struct flowi fl;
         unsigned        flags = 0;
         u32             itag = 0;
         struct rtable * rth;
@@ -2123,6 +2118,13 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
         /*
          *      Now we are ready to route packet.
          */
+        fl.oif = 0;
+        fl.iif = dev->ifindex;
+        fl.mark = skb->mark;
+        fl.fl4_dst = daddr;
+        fl.fl4_src = saddr;
+        fl.fl4_tos = tos;
+        fl.fl4_scope = RT_SCOPE_UNIVERSE;
         err = fib_lookup(net, &fl, &res);
         if (err != 0) {
                 if (!IN_DEV_FORWARD(in_dev))