net: Allow setting sock flow hash without a sock

This patch adds sock_rps_record_flow_hash and sock_rps_reset_flow_hash
which take a hash value as an argument and sets the sock_flow_table
accordingly.  This allows the table to be populated in cases where flow
is being tracked outside of a sock structure.

sock_rps_record_flow and sock_rps_reset_flow call this function
where the hash is taken from sk_rxhash.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sock.h

@@ -820,30 +820,40 @@ static inline int sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 	return sk->sk_backlog_rcv(sk, skb);
 }
 
-static inline void sock_rps_record_flow(const struct sock *sk)
+static inline void sock_rps_record_flow_hash(__u32 hash)
 {
 #ifdef CONFIG_RPS
 	struct rps_sock_flow_table *sock_flow_table;
 
 	rcu_read_lock();
 	sock_flow_table = rcu_dereference(rps_sock_flow_table);
-	rps_record_sock_flow(sock_flow_table, sk->sk_rxhash);
+	rps_record_sock_flow(sock_flow_table, hash);
 	rcu_read_unlock();
 #endif
 }
 
-static inline void sock_rps_reset_flow(const struct sock *sk)
+static inline void sock_rps_reset_flow_hash(__u32 hash)
 {
 #ifdef CONFIG_RPS
 	struct rps_sock_flow_table *sock_flow_table;
 
 	rcu_read_lock();
 	sock_flow_table = rcu_dereference(rps_sock_flow_table);
-	rps_reset_sock_flow(sock_flow_table, sk->sk_rxhash);
+	rps_reset_sock_flow(sock_flow_table, hash);
 	rcu_read_unlock();
 #endif
 }
 
+static inline void sock_rps_record_flow(const struct sock *sk)
+{
+	sock_rps_record_flow_hash(sk->sk_rxhash);
+}
+
+static inline void sock_rps_reset_flow(const struct sock *sk)
+{
+	sock_rps_reset_flow_hash(sk->sk_rxhash);
+}
+
 static inline void sock_rps_save_rxhash(struct sock *sk,
 					const struct sk_buff *skb)
 {