inet: convert inet_ehash_secret and ipv6_hash_secret to net_get_random_once

Initialize the ehash and ipv6_hash_secrets with net_get_random_once.

Each compilation unit gets its own secret now:
  ipv4/inet_hashtables.o
  ipv4/udp.o
  ipv6/inet6_hashtables.o
  ipv6/udp.o
  rds/connection.o

The functions still get inlined into the hashing functions. In the fast
path we have at most two (needed in ipv6) if (unlikely(...)).

Cc: Eric Dumazet <edumazet@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 1 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index b4437c7db6ce..89909dd730dd 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -411,8 +411,12 @@ static unsigned int udp_ehashfn(struct net *net, const __be32 laddr,
                                  const __u16 lport, const __be32 faddr,
                                  const __be16 fport)
 {
+        static u32 udp_ehash_secret __read_mostly;
+
+        net_get_random_once(&udp_ehash_secret, sizeof(udp_ehash_secret));
+
         return __inet_ehashfn(laddr, lport, faddr, fport,
-                              inet_ehash_secret + net_hash_mix(net));
+                              udp_ehash_secret + net_hash_mix(net));
 }