tun: use symmetric hash

Tun actually expects a symmetric hash for queue selecting to work
correctly, otherwise packets belongs to a single flow may be
redirected to the wrong queue. So this patch switch to use
__skb_get_hash_symmetric().

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/tun.c

@@ -465,7 +465,7 @@ static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb,
 	rcu_read_lock();
 	numqueues = ACCESS_ONCE(tun->numqueues);
 
-	txq = skb_get_hash(skb);
+	txq = __skb_get_hash_symmetric(skb);
 	if (txq) {
 		e = tun_flow_find(&tun->flows[tun_hashfn(txq)], txq);
 		if (e) {
@@ -867,7 +867,7 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
 		 */
 		__u32 rxhash;
 
-		rxhash = skb_get_hash(skb);
+		rxhash = __skb_get_hash_symmetric(skb);
 		if (rxhash) {
 			struct tun_flow_entry *e;
 			e = tun_flow_find(&tun->flows[tun_hashfn(rxhash)],
@@ -1334,7 +1334,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 	skb_reset_network_header(skb);
 	skb_probe_transport_header(skb, 0);
 
-	rxhash = skb_get_hash(skb);
+	rxhash = __skb_get_hash_symmetric(skb);
 #ifndef CONFIG_4KSTACKS
 	tun_rx_batched(tun, tfile, skb, more);
 #else