net: Set sk_txhash from a random number

This patch creates sk_set_txhash and eliminates protocol specific
inet_set_txhash and ip6_set_txhash. sk_set_txhash simply sets a
random number instead of performing flow dissection. sk_set_txash
is also allowed to be called multiple times for the same socket,
we'll need this when redoing the hash for negative routing advice.

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ip.h b/include/net/ip.h
index d5fe9f2..bee5f35 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -370,22 +370,6 @@
 	flow->control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
 }
 
-static inline void inet_set_txhash(struct sock *sk)
-{
-	struct inet_sock *inet = inet_sk(sk);
-	struct flow_keys keys;
-
-	memset(&keys, 0, sizeof(keys));
-
-	keys.addrs.v4addrs.src = inet->inet_saddr;
-	keys.addrs.v4addrs.dst = inet->inet_daddr;
-	keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
-	keys.ports.src = inet->inet_sport;
-	keys.ports.dst = inet->inet_dport;
-
-	sk->sk_txhash = flow_hash_from_keys(&keys);
-}
-
 static inline __wsum inet_gro_compute_pseudo(struct sk_buff *skb, int proto)
 {
 	const struct iphdr *iph = skb_gro_network_header(skb);
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 82dbdb0..7c79798 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -707,25 +707,6 @@
 }
 
 #if IS_ENABLED(CONFIG_IPV6)
-static inline void ip6_set_txhash(struct sock *sk)
-{
-	struct inet_sock *inet = inet_sk(sk);
-	struct ipv6_pinfo *np = inet6_sk(sk);
-	struct flow_keys keys;
-
-	memset(&keys, 0, sizeof(keys));
-
-	memcpy(&keys.addrs.v6addrs.src, &np->saddr,
-	       sizeof(keys.addrs.v6addrs.src));
-	memcpy(&keys.addrs.v6addrs.dst, &sk->sk_v6_daddr,
-	       sizeof(keys.addrs.v6addrs.dst));
-	keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
-	keys.ports.src = inet->inet_sport;
-	keys.ports.dst = inet->inet_dport;
-
-	sk->sk_txhash = flow_hash_from_keys(&keys);
-}
-
 static inline __be32 ip6_make_flowlabel(struct net *net, struct sk_buff *skb,
 					__be32 flowlabel, bool autolabel)
 {
diff --git a/include/net/sock.h b/include/net/sock.h
index 4353ef7..fe735c4 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1687,6 +1687,14 @@
 kuid_t sock_i_uid(struct sock *sk);
 unsigned long sock_i_ino(struct sock *sk);
 
+static inline void sk_set_txhash(struct sock *sk)
+{
+	sk->sk_txhash = prandom_u32();
+
+	if (unlikely(!sk->sk_txhash))
+		sk->sk_txhash = 1;
+}
+
 static inline struct dst_entry *
 __sk_dst_get(struct sock *sk)
 {